The document summarizes design features used to achieve defence-in-depth in innovative small and medium sized reactor concepts with fast neutron spectrums, as described in an IAEA report. It focuses on sodium and lead cooled fast reactor designs, including the 4S-LMR and SSTAR concepts. These reactor designs aim to eliminate accident initiators and prevent consequences through inherent and passive safety features enabled by their smaller size, such as passive shutdown capability and natural convection decay heat removal without active systems.
VVER reactors are pressurized water reactors originally developed in the Soviet Union/Russia. The document discusses the history and evolution of VVER reactor designs from early Generation I and II models through current Generation III+ designs. It provides details on VVER-440, VVER-1000, VVER-1200 and planned VVER-1500 models, describing their key features, safety improvements over time, and global proliferation. Countries operating VVER reactors include Russia, Ukraine, Hungary, Finland, Bulgaria, Slovakia, Czech Republic, China, India, Iran and others.
This presentation discusses the safety aspects of nuclear power plant design with respect to design basis parameters. It introduces concepts of nuclear safety and defense-in-depth. The document outlines safety objectives, requirements for multiple barriers and redundancy. It describes categories of postulated initiating events and how common cause failures are addressed. Safety classification and detailed design rules are also summarized. Finally, the presentation provides an overview of site-specific external hazards for the Rooppur Nuclear Power Plant in Bangladesh and compares its design basis safety to that of VVER reactor designs.
The document provides an overview of the Advanced Power Reactor 1400 MWe (APR1400), a pressurized water reactor (PWR) developed in South Korea. Some key details include:
- The APR1400 has a thermal capacity of 3,983 MWth and gross electrical capacity of 1,455 MWe.
- It is based on experience from South Korea's OPR1000 reactor and incorporates advanced safety features.
- Major components include a reactor vessel, two reactor coolant loops, two steam generators, two reactor coolant pumps, and a pressurizer.
Doosan Heavy Industries is a global leader in supplying nuclear power plants and equipment. It has extensive experience designing and manufacturing components for nuclear power plants in Korea and worldwide. This includes supplying equipment for 15 nuclear power plants in Korea as well as components for replacement projects in the US. Doosan is also a leading manufacturer of AP1000 nuclear reactors, having won contracts to supply reactors for nuclear plants in China and the US.
Westinghouse PWR Design Comparison: Gen II versus Gen IIIJonathan Varesko
An overview and comparison between two Westinghouse nuclear power plants, one a Gen II reactor built in the 1960s and one a Gen III reactor currently being built at four nuclear sites around the world today.
This document provides information on various types of nuclear reactors, including their basic designs and operating principles. It describes six main commercial reactor types (Magnox, AGR, PWR, BWR, CANDU, RBMK), as well as prototype designs like the IRIS, PBMR and fast reactors. Key details are given for each type such as coolant, moderator, fuel type, operating temperatures and pressures. Current developments discussed include the Next Generation CANDU and Advanced PWR designs.
The document summarizes the main types of nuclear reactors, including:
1) Gas cooled, graphite moderated reactors like Magnox and AGR reactors which use carbon dioxide gas and graphite.
2) Heavy water cooled and moderated CANDU reactors which use heavy water as both coolant and moderator.
3) Water cooled and moderated reactors like Pressurized Water Reactors (PWR) and Boiling Water Reactors (BWR) which use ordinary water as both coolant and moderator.
4) Water cooled, graphite moderated RBMK reactors which use graphite as a moderator and water as a coolant, allowing it to boil directly.
Science and technology of supercritical water cooled reactors review and statusAlexander Decker
1) The document provides an overview of Supercritical Water-Cooled Reactor (SCWR) concepts being developed globally as a way to increase the efficiency and reduce costs of modern nuclear power plants.
2) SCWRs operate with water as the coolant above the critical pressure of 22.1 MPa to achieve higher temperatures than traditional pressurized water reactors. This allows efficiencies as high as 45% compared to 33-35% for current reactors.
3) Two notable SCWR concepts discussed are from Canada, which builds upon its CANDU reactor design with heavy water moderator, and the European Union's High Performance Light Water Reactor design with a three-zone core layout. Both aim
VVER reactors are pressurized water reactors originally developed in the Soviet Union/Russia. The document discusses the history and evolution of VVER reactor designs from early Generation I and II models through current Generation III+ designs. It provides details on VVER-440, VVER-1000, VVER-1200 and planned VVER-1500 models, describing their key features, safety improvements over time, and global proliferation. Countries operating VVER reactors include Russia, Ukraine, Hungary, Finland, Bulgaria, Slovakia, Czech Republic, China, India, Iran and others.
This presentation discusses the safety aspects of nuclear power plant design with respect to design basis parameters. It introduces concepts of nuclear safety and defense-in-depth. The document outlines safety objectives, requirements for multiple barriers and redundancy. It describes categories of postulated initiating events and how common cause failures are addressed. Safety classification and detailed design rules are also summarized. Finally, the presentation provides an overview of site-specific external hazards for the Rooppur Nuclear Power Plant in Bangladesh and compares its design basis safety to that of VVER reactor designs.
The document provides an overview of the Advanced Power Reactor 1400 MWe (APR1400), a pressurized water reactor (PWR) developed in South Korea. Some key details include:
- The APR1400 has a thermal capacity of 3,983 MWth and gross electrical capacity of 1,455 MWe.
- It is based on experience from South Korea's OPR1000 reactor and incorporates advanced safety features.
- Major components include a reactor vessel, two reactor coolant loops, two steam generators, two reactor coolant pumps, and a pressurizer.
Doosan Heavy Industries is a global leader in supplying nuclear power plants and equipment. It has extensive experience designing and manufacturing components for nuclear power plants in Korea and worldwide. This includes supplying equipment for 15 nuclear power plants in Korea as well as components for replacement projects in the US. Doosan is also a leading manufacturer of AP1000 nuclear reactors, having won contracts to supply reactors for nuclear plants in China and the US.
Westinghouse PWR Design Comparison: Gen II versus Gen IIIJonathan Varesko
An overview and comparison between two Westinghouse nuclear power plants, one a Gen II reactor built in the 1960s and one a Gen III reactor currently being built at four nuclear sites around the world today.
This document provides information on various types of nuclear reactors, including their basic designs and operating principles. It describes six main commercial reactor types (Magnox, AGR, PWR, BWR, CANDU, RBMK), as well as prototype designs like the IRIS, PBMR and fast reactors. Key details are given for each type such as coolant, moderator, fuel type, operating temperatures and pressures. Current developments discussed include the Next Generation CANDU and Advanced PWR designs.
The document summarizes the main types of nuclear reactors, including:
1) Gas cooled, graphite moderated reactors like Magnox and AGR reactors which use carbon dioxide gas and graphite.
2) Heavy water cooled and moderated CANDU reactors which use heavy water as both coolant and moderator.
3) Water cooled and moderated reactors like Pressurized Water Reactors (PWR) and Boiling Water Reactors (BWR) which use ordinary water as both coolant and moderator.
4) Water cooled, graphite moderated RBMK reactors which use graphite as a moderator and water as a coolant, allowing it to boil directly.
Science and technology of supercritical water cooled reactors review and statusAlexander Decker
1) The document provides an overview of Supercritical Water-Cooled Reactor (SCWR) concepts being developed globally as a way to increase the efficiency and reduce costs of modern nuclear power plants.
2) SCWRs operate with water as the coolant above the critical pressure of 22.1 MPa to achieve higher temperatures than traditional pressurized water reactors. This allows efficiencies as high as 45% compared to 33-35% for current reactors.
3) Two notable SCWR concepts discussed are from Canada, which builds upon its CANDU reactor design with heavy water moderator, and the European Union's High Performance Light Water Reactor design with a three-zone core layout. Both aim
"The Westinghouse Pressurized
Water Reactor Nuclear Power Plant" is a
complete revision of the "Systems Summary of a
Westinghouse Pressurized Water Reactor
Nuclear Power Plant" published in 1971 with
subsequent reprintings.
This document describes revisions made to the design characteristics stored in the IAEA's Power Reactor Information System database. It overviews the structure of the new design characteristics, which are organized into primary systems, balance-of-plant systems, spent fuel storage, and non-electrical applications. The revisions aimed to provide a more comprehensive overview of nuclear power plant designs and address issues like incomplete or missing data.
This document provides an overview of nuclear reactors, including their classification, main components, the nuclear fission reaction, and different reactor types. It discusses reactors based on neutron energy, coolant used, moderator, and fuel enrichment. The main components of a nuclear reactor are described as the fuel, moderator, coolant, control rods, and shielding. Examples of reactor types are provided and compared such as BWR, PWR, PHWR, GCR, LWGR, and FBR. Current and planned nuclear reactor units in India are also listed.
There are several types of nuclear reactors classified by their operation, purpose, fuel, and coolant. Reactors are either thermalized, which slow neutrons, or fast reactors. Their purpose can be power production, fuel conversion, breeding more fuel (breeder reactors), or research. Breeder reactors produce more fissile plutonium than they consume. Reactors also differ in whether they use solid, liquid, or gas fuels and water, heavy water, liquid metals like sodium, or gases like carbon dioxide as coolants. The most common reactor types are light water reactors (using regular water), boiling water reactors, and pressurized heavy water reactors.
Advanced nuclear reactor in nuclear power stationUday Wankar
A nuclear reactor is a device to initiate and control a sustained nuclear chain reaction. Nuclear reactors are used at nuclear power plants for electricity generation and in propulsion of ships. Heat from nuclear fission is passed to a working fluid (water or gas), which runs through turbines. These either drive a ship's propellers or turn electrical generators. Nuclear generated steam in principle can be used for industrial process heat or for district heating. Some reactors are used to produce isotopes for medical and industrial use, or for production of plutonium for weapons. Some are run only for research. Today there are about 450 nuclear power reactors that are used to generate electricity in about 30 countries around the world.
Nuclear reactors, A collaborative approach towards main streams and a general...MBabarYaqoob
An essence towards a quick and authentic approach regarding nuclear reactors including important ingredients like history, generations up-to-date made, a reasonable package of types of reactors, pros & cons and a touch of accidents happened in nuclear reactors.
Pressurized Water Reactor Simulated by TRACETroy Todd
The report summarizes the development of a model of a four loop pressurized water reactor (PWR) using TRACE software. Key components modeled included the steam generator, reactor vessel and cores, pressurizer, pump, and turbine. Parameters and equations used to develop the geometry and inputs of each component are described. The goal of the model is to achieve steady state operation and evaluate plant behavior under transient conditions by analyzing output plots of temperatures, pressures, flow rates and other variables.
David Lochbaum High Level Nuclear Waste-20120630MATRRorg
High Level Nuclear Waste presentation The Magic of Spent Fuel by David Lochbaum, Director, Nuclear Safety, Union of Concerned Scientists at the KNOW NUKES Y'ALL SUMMIT on June 30, 2012.
This document discusses the components and types of nuclear reactors. It describes six main types: 1) pressurized water reactors, 2) boiling water reactors, 3) pressurized heavy water reactors, 4) advanced gas-cooled reactors, 5) RBMK light water graphite-moderated reactors, and 6) fast neutron reactors. Common components include fuel rods, moderator, control rods, coolant, and pressure vessels. Pressurized water reactors are the most common type and use water as both coolant and moderator under high pressure.
The document discusses the CANDU nuclear reactor, a pressurized heavy water reactor designed in Canada. It provides details on the design of CANDU reactors, including their use of natural uranium fuel and heavy water as both moderator and coolant. CANDU reactors allow for online refueling without shutdown and have safety features like shutdown rods and poison injection. The document also outlines the pros and cons of CANDU reactors and their contribution to nuclear energy globally, with over 20 reactors operating or under construction in 7 countries.
This document describes the Westinghouse AP1000 advanced passive nuclear power plant. The AP1000 is a larger, 1000 MWe version of the AP600 plant that uses proven passive safety technology. It retains most of the simplified design of the AP600 to reduce costs and complexity. Major components like the reactor, steam generators, and pumps are based on extensively tested and proven existing technology from operating PWR plants with some enhancements. Westinghouse is working to complete design certification for the AP1000 by 2004 to enable its deployment in the US market.
Westinghouse PWR Design Comparison: Gen II versus Gen IIIJonathan Varesko
The document compares the Westinghouse Pressurized Water Reactors Generation II (R.E. Ginna nuclear power plant) and Generation III+ (AP1000) reactor designs. Key differences include the AP1000 having a passive core cooling system and containment cooling system, a more efficient 4-loop design, digital instrumentation, and reduced operation and maintenance costs. The AP1000 represents an advancement in nuclear reactor safety, reliability and cost-effectiveness.
CANDU reactors were first developed in the 1950s-1960s in Canada as a partnership between government and private organizations. CANDU reactors use natural uranium fuel, pressurized heavy water as a moderator, and pressurized tubes to contain the fuel and coolant as it circulates. Key components include the pressurized fuel tubes, fuel elements, reactor core, steam generator, turbines, condenser, and cooling water. Neutrons are slowed by heavy water, heating it up which is then used to power the turbines and generate electricity. Control rods are used for start-up, shutdown, and regulating power during operation. Advantages include not requiring enriched fuel and low fuel consumption, while disadvantages include the high
Types of Nuclear Reactors,BWR,Boiling Water Reactor,PWR,Pressurized Water Reactor,PHWR,Pressurised Heavy Water Reactor,GCR,Gas Cooled Reactor,AGR,Advanced Gas-Cooled Reactor,LGR-Light Water Cooled,Graphite Moderated Reactor,nuclear reactor
The document provides basic design information about BWR3 and BWR4 reactors, which are the types used at the Fukushima Daiichi nuclear power plant. It describes the Mark I containment system, typical reactor vessel configurations, and the reactor core isolation cooling system. It then summarizes the events at Fukushima Daiichi following the 2011 earthquake and tsunami, including loss of cooling, hydrogen explosions, fuel damage in reactors 1-3, and challenges with spent fuel pools.
1) Fast-neutron reactors could extract more energy from recycled nuclear fuel than current reactors, reduce nuclear proliferation risks, and markedly decrease the time nuclear waste must be isolated.
2) The article discusses how fast-neutron reactors and pyrometallurgical processing of spent nuclear fuel could form a nuclear fuel cycle that reduces radioactivity in waste to safe levels within a few hundred years, eliminating the need to isolate waste for tens of thousands of years.
3) Current nuclear power plants produce waste that remains highly radioactive for thousands of years, but fast-neutron reactors and recycling could make nuclear power truly sustainable and reduce its drawbacks related to waste and resource depletion.
Marine electrical distribution system and control engineeringZeeshan Ahmed
The document discusses the electrical systems and components onboard ships, including marine electrical distribution systems, generator parts, high voltage cables, switchboards, motor starters, and control systems like PLC and DCS. It also outlines the various electrical repair and maintenance work performed by marine engineers, such as overhauling motors and generators, working on control valves, and training in an electrical and electronic shop. The author introduction provides background on the author's marine engineering education and training with the Pakistan National Shipping Corporation.
Advanced nuclear reactors like small modular reactors and fast reactors are being developed that offer improvements over current light water reactors. Small modular reactors would be smaller in size (up to 300 MW) and could be deployed more quickly. Fast reactors operate at high neutron energies without a moderator and can potentially consume nuclear waste as fuel in a closed fuel cycle. However, small modular reactors may generate more radioactive waste volumes than large light water reactors. Advanced reactors will require solutions for managing their different types of nuclear waste that current disposal methods may not be compatible with.
Comparative analysis of water cooled reactor design models and gas-cooled rea...Alexander Decker
This document presents a comparative analysis of water-cooled reactor design models and gas-cooled reactor design models. Linear regression analysis is applied to four reactor design models: a water-cooled reactor design I, a water-cooled reactor design II, a gas-cooled reactor design I, and a gas-cooled reactor design II. Empirical expressions are obtained for the safety factor of each design model based on coolant flow rate. The results of statistical analysis reveal that the gas-cooled reactor design II model promises to be the most stable based on safety factor. The implications for Nigeria's nuclear power project are discussed.
"The Westinghouse Pressurized
Water Reactor Nuclear Power Plant" is a
complete revision of the "Systems Summary of a
Westinghouse Pressurized Water Reactor
Nuclear Power Plant" published in 1971 with
subsequent reprintings.
This document describes revisions made to the design characteristics stored in the IAEA's Power Reactor Information System database. It overviews the structure of the new design characteristics, which are organized into primary systems, balance-of-plant systems, spent fuel storage, and non-electrical applications. The revisions aimed to provide a more comprehensive overview of nuclear power plant designs and address issues like incomplete or missing data.
This document provides an overview of nuclear reactors, including their classification, main components, the nuclear fission reaction, and different reactor types. It discusses reactors based on neutron energy, coolant used, moderator, and fuel enrichment. The main components of a nuclear reactor are described as the fuel, moderator, coolant, control rods, and shielding. Examples of reactor types are provided and compared such as BWR, PWR, PHWR, GCR, LWGR, and FBR. Current and planned nuclear reactor units in India are also listed.
There are several types of nuclear reactors classified by their operation, purpose, fuel, and coolant. Reactors are either thermalized, which slow neutrons, or fast reactors. Their purpose can be power production, fuel conversion, breeding more fuel (breeder reactors), or research. Breeder reactors produce more fissile plutonium than they consume. Reactors also differ in whether they use solid, liquid, or gas fuels and water, heavy water, liquid metals like sodium, or gases like carbon dioxide as coolants. The most common reactor types are light water reactors (using regular water), boiling water reactors, and pressurized heavy water reactors.
Advanced nuclear reactor in nuclear power stationUday Wankar
A nuclear reactor is a device to initiate and control a sustained nuclear chain reaction. Nuclear reactors are used at nuclear power plants for electricity generation and in propulsion of ships. Heat from nuclear fission is passed to a working fluid (water or gas), which runs through turbines. These either drive a ship's propellers or turn electrical generators. Nuclear generated steam in principle can be used for industrial process heat or for district heating. Some reactors are used to produce isotopes for medical and industrial use, or for production of plutonium for weapons. Some are run only for research. Today there are about 450 nuclear power reactors that are used to generate electricity in about 30 countries around the world.
Nuclear reactors, A collaborative approach towards main streams and a general...MBabarYaqoob
An essence towards a quick and authentic approach regarding nuclear reactors including important ingredients like history, generations up-to-date made, a reasonable package of types of reactors, pros & cons and a touch of accidents happened in nuclear reactors.
Pressurized Water Reactor Simulated by TRACETroy Todd
The report summarizes the development of a model of a four loop pressurized water reactor (PWR) using TRACE software. Key components modeled included the steam generator, reactor vessel and cores, pressurizer, pump, and turbine. Parameters and equations used to develop the geometry and inputs of each component are described. The goal of the model is to achieve steady state operation and evaluate plant behavior under transient conditions by analyzing output plots of temperatures, pressures, flow rates and other variables.
David Lochbaum High Level Nuclear Waste-20120630MATRRorg
High Level Nuclear Waste presentation The Magic of Spent Fuel by David Lochbaum, Director, Nuclear Safety, Union of Concerned Scientists at the KNOW NUKES Y'ALL SUMMIT on June 30, 2012.
This document discusses the components and types of nuclear reactors. It describes six main types: 1) pressurized water reactors, 2) boiling water reactors, 3) pressurized heavy water reactors, 4) advanced gas-cooled reactors, 5) RBMK light water graphite-moderated reactors, and 6) fast neutron reactors. Common components include fuel rods, moderator, control rods, coolant, and pressure vessels. Pressurized water reactors are the most common type and use water as both coolant and moderator under high pressure.
The document discusses the CANDU nuclear reactor, a pressurized heavy water reactor designed in Canada. It provides details on the design of CANDU reactors, including their use of natural uranium fuel and heavy water as both moderator and coolant. CANDU reactors allow for online refueling without shutdown and have safety features like shutdown rods and poison injection. The document also outlines the pros and cons of CANDU reactors and their contribution to nuclear energy globally, with over 20 reactors operating or under construction in 7 countries.
This document describes the Westinghouse AP1000 advanced passive nuclear power plant. The AP1000 is a larger, 1000 MWe version of the AP600 plant that uses proven passive safety technology. It retains most of the simplified design of the AP600 to reduce costs and complexity. Major components like the reactor, steam generators, and pumps are based on extensively tested and proven existing technology from operating PWR plants with some enhancements. Westinghouse is working to complete design certification for the AP1000 by 2004 to enable its deployment in the US market.
Westinghouse PWR Design Comparison: Gen II versus Gen IIIJonathan Varesko
The document compares the Westinghouse Pressurized Water Reactors Generation II (R.E. Ginna nuclear power plant) and Generation III+ (AP1000) reactor designs. Key differences include the AP1000 having a passive core cooling system and containment cooling system, a more efficient 4-loop design, digital instrumentation, and reduced operation and maintenance costs. The AP1000 represents an advancement in nuclear reactor safety, reliability and cost-effectiveness.
CANDU reactors were first developed in the 1950s-1960s in Canada as a partnership between government and private organizations. CANDU reactors use natural uranium fuel, pressurized heavy water as a moderator, and pressurized tubes to contain the fuel and coolant as it circulates. Key components include the pressurized fuel tubes, fuel elements, reactor core, steam generator, turbines, condenser, and cooling water. Neutrons are slowed by heavy water, heating it up which is then used to power the turbines and generate electricity. Control rods are used for start-up, shutdown, and regulating power during operation. Advantages include not requiring enriched fuel and low fuel consumption, while disadvantages include the high
Types of Nuclear Reactors,BWR,Boiling Water Reactor,PWR,Pressurized Water Reactor,PHWR,Pressurised Heavy Water Reactor,GCR,Gas Cooled Reactor,AGR,Advanced Gas-Cooled Reactor,LGR-Light Water Cooled,Graphite Moderated Reactor,nuclear reactor
The document provides basic design information about BWR3 and BWR4 reactors, which are the types used at the Fukushima Daiichi nuclear power plant. It describes the Mark I containment system, typical reactor vessel configurations, and the reactor core isolation cooling system. It then summarizes the events at Fukushima Daiichi following the 2011 earthquake and tsunami, including loss of cooling, hydrogen explosions, fuel damage in reactors 1-3, and challenges with spent fuel pools.
1) Fast-neutron reactors could extract more energy from recycled nuclear fuel than current reactors, reduce nuclear proliferation risks, and markedly decrease the time nuclear waste must be isolated.
2) The article discusses how fast-neutron reactors and pyrometallurgical processing of spent nuclear fuel could form a nuclear fuel cycle that reduces radioactivity in waste to safe levels within a few hundred years, eliminating the need to isolate waste for tens of thousands of years.
3) Current nuclear power plants produce waste that remains highly radioactive for thousands of years, but fast-neutron reactors and recycling could make nuclear power truly sustainable and reduce its drawbacks related to waste and resource depletion.
Marine electrical distribution system and control engineeringZeeshan Ahmed
The document discusses the electrical systems and components onboard ships, including marine electrical distribution systems, generator parts, high voltage cables, switchboards, motor starters, and control systems like PLC and DCS. It also outlines the various electrical repair and maintenance work performed by marine engineers, such as overhauling motors and generators, working on control valves, and training in an electrical and electronic shop. The author introduction provides background on the author's marine engineering education and training with the Pakistan National Shipping Corporation.
Advanced nuclear reactors like small modular reactors and fast reactors are being developed that offer improvements over current light water reactors. Small modular reactors would be smaller in size (up to 300 MW) and could be deployed more quickly. Fast reactors operate at high neutron energies without a moderator and can potentially consume nuclear waste as fuel in a closed fuel cycle. However, small modular reactors may generate more radioactive waste volumes than large light water reactors. Advanced reactors will require solutions for managing their different types of nuclear waste that current disposal methods may not be compatible with.
Comparative analysis of water cooled reactor design models and gas-cooled rea...Alexander Decker
This document presents a comparative analysis of water-cooled reactor design models and gas-cooled reactor design models. Linear regression analysis is applied to four reactor design models: a water-cooled reactor design I, a water-cooled reactor design II, a gas-cooled reactor design I, and a gas-cooled reactor design II. Empirical expressions are obtained for the safety factor of each design model based on coolant flow rate. The results of statistical analysis reveal that the gas-cooled reactor design II model promises to be the most stable based on safety factor. The implications for Nigeria's nuclear power project are discussed.
The document discusses the evolution and advanced designs of VVER reactors. It describes the current challenges facing nuclear power plants and how generation 3+ designs, such as the VVER-1200, aim to address these through extended lifetimes, reduced costs and construction times. Future innovative designs discussed include the VVER-600, VVER-SCP generation 4 supercritical water cooled reactor, and concepts using tight fuel assemblies for a closed nuclear fuel cycle. The VVER-1200 design for project AES-2006 forms the basis for the further developed MIR-1200 design being implemented in the Czech Republic.
Stability margin analysis of gas cooled reactor design modelsAlexander Decker
The document describes a study that uses linear regression analysis to analyze the stability margin of three different gas-cooled nuclear reactor design models (GCRD I, GCRD II, GCRD III). Design input data including safety factor and coolant flow rates were collected for each model. Regression equations were obtained relating safety factor to coolant flow rate for each model. Analysis of the regression results found that GCRD III has the highest correlation and lowest error, indicating it promises to be the most stable and safest design.
The document discusses a nuclear power station in Bangladesh that is being built by ROSATOM. It will have two VVER-1200/523 pressurized water reactors with a total nameplate capacity of 2,160 MW. Reactor 1 is scheduled to begin operation in 2023 and Reactor 2 in 2024. The document also provides information on the basic principles of nuclear fission, the role of control rods and moderators, and some of the environmental issues associated with nuclear power such as radioactive waste and decommissioning of reactors.
Role of relap scdapsim in nuclear safetyBrian Allison
The document discusses the RELAP/SCDAPSIM code, which is used to predict reactor system behavior during normal and accident conditions. It is part of an international development program involving nearly 60 organizations. The code is used to analyze research reactors, nuclear power plants, experiments, and for training. It can model a variety of reactor types and is being further developed to improve accuracy and add new capabilities.
This document summarizes a project to size equipment and design the earthing and protection systems for the Pakistan Refinery Limited grid station. It includes calculations to size the earthing mesh, power and auxiliary transformers, current and voltage transformers, capacitor bank, cables, circuit breakers, and battery bank. Short circuit analysis was performed using ETAP software. The objectives were to ensure reliable and economic operation of the grid station within KESC specifications. Problems encountered included meeting grounding requirements and transformer sizing, which were solved by adding more grounding rods and selecting a step-lap core design respectively.
Transatomic Power (TAP) is developing an advanced molten salt reactor that generates clean, passively safe, proliferation-resistant, and low-cost nuclear power. This reactor can consume the spent nuclear fuel (SNF) generated by commercial light water reactors or use freshly mined uranium at enrichment levels as low as 1.8% U-235. It achieves actinide burnups as high as 96%, and can generate up to 75 times more electricity per ton of mined uranium than a light-water reactor.
Source: http://transatomicpower.com/white_papers/TAP_White_Paper.pdf
Key Features of MIR.1200 (AES-2006) design and current stage of Leningrad NP...myatom
The document discusses the key features and current construction status of the MIR.1200/AES-2006 nuclear power plant design and Leningrad NPP-2, which uses this design. The MIR.1200 design is an evolution of previous VVER reactor designs with improved safety features like a double containment structure and passive safety systems. Leningrad NPP-2 Units 1 and 2 are currently under construction in Russia using this design. The design provides enhanced safety, economics, and project attractiveness through an evolutionary approach and leveraging designs already implemented in other plants.
ESs have several advantages over batteries such as very short charge/discharge times, long life cycles, and high power densities. They are well-suited for applications requiring backup power, fast response times, and reduced size. Some key applications discussed include power electronics, memory protection, and battery enhancement to increase device run-times. ESs can replace batteries in RAID systems and provide backup power to DRAM, protecting data during power failures. When used alongside batteries, ESs can increase portable device run-times by quickly accepting and discharging power.
An in-depth study of the electrical characterization of supercapacitors for r...VIT-AP University
The Energy Storage System (ESS) is geared toward sophisticated systems with increased operating time for a variety of real-time applications such as an electric vehicle, a WSN (Wireless Sensor Network), a Capa bus, and so
on. Its primary focus is on supplying these kinds of systems with additional capacity in recent development, and
this will continue to be its primary focus. Because of their exceptionally high specific power, rapid charging, and
low ESR (Effective Series Resistance), electric double-layer (EDLC) capacitors or supercapacitors are encouraged
for use because they can be integrated more easily with battery technology that can be used in electric vehicles
and other electronic devices. The supercapacitor calls for a precise and accurate characterization in order to
facilitate the development of improved applications and more effective energy storage devices and technologies.
In this article, we studied various supercapacitor electrode components, electrolytic solutions, analogous circuit
models, electrical energy storage properties, and some real-time supercapacitor applications in the automotive,
manufacturing, construction, and consumer electronics industries. In addition, we have discussed on hybrid
material that was just recently developed with the goal of enhancing the conductivity and effectiveness of supercapacitors. Aside from this, we have discussed about the behaviour of supercapacitors in terms of how their behaviour is dependent on current and voltage with detailed analysis.
Study of pressurized water reactor design modelsAlexander Decker
This document discusses a study that applied linear regression analysis to two pressurized water reactor (PWR) design models, referred to as PWRD I and PWRD II. Input data on coolant flow rates and safety factors from actual PWRs were used to develop regression models for each design. The results found that the PWRD II model had a higher R2 value and lower error, indicating it promises to be more stable and safer than the PWRD I model. The implications for Nigeria's nuclear power project are also discussed.
День атомної енергетики 2014. Стратегія управління важкими аваріями «Внутрішн...НАЕК «Енергоатом»
День атомної енергетики 2014. Доповідь: «In vessel melt retention for VVER 1000»
«Стратегія управління важкими аваріями «Внутрішньокорпусне утримання розплаву активної зони РУ ВВЕР-1000». Їржи Ждярек, віце-президент з ділового розвитку інституту ядерних досліджень Ржеж (Чехія)
This document discusses nuclear batteries as a long-lasting power source. It begins by explaining the need for compact, reliable power supplies that do not require frequent replacement like chemical batteries. Nuclear batteries generate electricity from radioactive isotopes and can last for decades. The document then covers various types of nuclear batteries such as direct charging generators that use alpha and beta particle emissions, as well as betavoltaic cells that convert beta radiation into electricity similar to solar cells. Applications discussed include use in space, medical devices, mobile electronics, and sensors. Advantages highlighted are extremely long lifespan, compact size, and ability to provide power in remote locations.
IRJET- Modeling and Simulation of Superconducting Magnetic Storage System in ...IRJET Journal
This document reviews modeling and simulation of superconducting magnetic storage systems in power systems. It discusses how superconducting magnetic energy storage (SMES) systems can store excess electric energy as electromagnetic energy in high-temperature superconducting inductors. The document presents the advantages of SMES systems for applications like power system load leveling and provides a literature review on previous SMES research. It also describes the theoretical basis for SMES systems using superconducting wires and coils and concludes that the developed mathematical model can output the charging and storage characteristics of an SMES system given certain input parameters.
Computer Integrated Design, Analysis and Shape Optimization of Proton Beam DumpIRJET Journal
This document discusses the computer integrated design, analysis, and shape optimization of a proton beam dump. It first provides background on spallation neutron sources and the issues they present, such as induced radioactivity. It then reviews previous literature on related topics like negative ion sources and beam dump design. The document proposes using simulation software to derive results from one module to input into another for shape optimization of the beam dump's cooling channel, ensuring thermal and structural stability for high-powered proton beams.
A review on predictive maintenance technique for nuclear reactor cooling sys...IJECEIAES
Reactor TRIGA PUSPATI (RTP) is the only research nuclear reactor in Malaysia. Maintenance of RTP is crucial which affects its safety and reliability. Currently, RTP maintenance strategies used corrective and preventative which involved many sensors and equipment conditions. The existing preventive maintenance method takes a longer time to complete the entire system’s maintenance inspection. This study has investigated new predictive maintenance techniques for developing RTP predictive maintenance for primary cooling systems using machine learning (ML) and augmented reality (AR). Fifty papers from recent referred publications in the nuclear areas were reviewed and compared. Detailed comparison of ML techniques, parameters involved in the coolant system and AR design techniques were done. Multiclass support vector machines (SVMs), artificial neural network (ANN), long short-term memory (LSTM), feed forward back propagation (FFBP), graph neural networks-feed forward back propagation (GNN-FFBP) and ANN were used for the machine learning techniques for the nuclear reactor. Temperature, water flow, and water pressure were crucial parameters used in monitoring a nuclear reactor. Image marker-based techniques were mainly used by smart glass view and handheld devices. A switch knob with handle switch, pipe valve and machine feature were used for object detection in AR markerless technique. This study is significant and found seven recent papers closely related to the development of predictive maintenance for a research nuclear reactor in Malaysia.
IRJET- Review Paper Hybrid Energy Storage System Micro Grid Integration with ...IRJET Journal
The document summarizes a research paper on integrating a hybrid energy storage system into a microgrid using a four leg three level neutral point clamped inverter. The hybrid energy storage system combines the advantages of vanadium redox batteries and lithium-ion batteries. A four leg inverter topology is used to interface the renewable energy sources and hybrid energy storage system to the microgrid. A control strategy is developed using second order sliding mode control to manage the power flow between the energy storage systems and improve power quality. Experimental results showed the control strategy was effective at controlling the renewable energy injected into the microgrid and managing the hybrid energy storage system.
Similar to IAEA, Small and Medium Size Reactors 2009, Kuznetsov (20)
The document summarizes the major systems and components of a boiling water reactor (BWR) plant. It describes the reactor vessel internals that produce steam from heating water, the moisture separators and dryers, main turbine system that converts steam to electricity, and emergency core cooling systems. The BWR uses circulating water to transfer heat from the reactor core to power the main turbine, and has safety systems to inject water into the reactor vessel in the event of a loss of coolant accident.
This document summarizes updated capital cost estimates for various electricity generation technologies that were commissioned by the U.S. Energy Information Administration. Key findings include that overnight capital costs for coal and nuclear plants are 25-37% higher than prior estimates, while natural gas costs remained similar. Solar photovoltaic costs declined 25% due to larger plant sizes and lower component costs. Onshore wind costs increased 21%, while offshore wind costs increased 50% to reflect first-of-a-kind U.S. project costs. Geothermal and biomass costs also increased versus prior estimates. These updated cost estimates will be used in EIA's modeling and analysis of technology choices in the electric power sector.
10 years of experience with Westinghouse fuel at NPP Temelinmyatom
Westinghouse fuel has been used at the Temelin NPP for 10 years. Some key points include:
- The first Westinghouse fuel assembly was loaded in 2000 and the plant achieved first criticality 3 months later. There have been 15 fuel cycles representing 960 fuel assemblies.
- Issues encountered include incomplete rod insertions, fuel assembly bowing and growth, and leaking fuel rods. Modifications to fuel assembly designs have helped address these issues.
- A post-irradiation inspection program provided data on fuel performance to support continued licensing of new fuel designs. While visual examinations showed little corrosion, measurements revealed unexpected fuel assembly twisting and bowing.
TVSA-T fuel assembly for “Temelin” NPP. Main results of design and safety ana...myatom
The document summarizes the design and safety analyses of the TVSA-T fuel assembly developed for the Temelin NPP in the Czech Republic. Key points include:
1) TVSA-T is based on the proven TVSA design with additional modifications like combined spacer grids and a longer fuel column.
2) Extensive testing and analyses were conducted to validate the TVSA-T design including thermohydraulic tests, mechanical tests, and safety analyses.
3) The design was successfully licensed for use at Temelin NPP unit 1 and meets all safety criteria for normal operation and accident conditions.
This document discusses the power uprate project at the NPP Temelín nuclear power plant in the Czech Republic. The project aims to increase the reactor thermal power from 3000 MWt to 3120 MWt and install new turbine low pressure parts to boost the generator output from 1016 MWe to 1081 MWe. The project will be carried out through analytical evaluations, core design updates, safety analysis revisions, and minor equipment modifications. It is scheduled to be implemented at Unit 1 in 2012 while ensuring the plant's safety criteria and limits remain unchanged.
This document discusses materials used for equipment in reactor plants V-320 and V-491. It provides details on the reactor pressure vessel such as dimensions, mass, and steel grades used for different components. It also discusses how materials were improved for V-491 to decrease radiation embrittlement and increase brittle fracture resistance. Surveillance programs and specifications for specimens are outlined to monitor changes in pressure vessel material properties during operation. Regulatory requirements for equipment design, welding, and inspections are also summarized.
Rothwell Braun THE COST STRUCTURE OF INTERNATIONAL URANIUM ENRICHMENT SERVICE...myatom
This document analyzes the international uranium enrichment services market. It finds that as older gaseous diffusion plants are retired, the supply curve will shift, lowering prices. By 2015, prices could drop 41% to $80/SWU from $135/SWU in 2005 due to increased centrifuge capacity. However, lower prices may decrease profits and investment incentives, so some market intervention may be needed to control prices and discourage proliferation of enrichment technology to non-fuel states.
[OReilly Superstream] Occupy the Space: A grassroots guide to engineering (an...Jason Yip
The typical problem in product engineering is not bad strategy, so much as “no strategy”. This leads to confusion, lack of motivation, and incoherent action. The next time you look for a strategy and find an empty space, instead of waiting for it to be filled, I will show you how to fill it in yourself. If you’re wrong, it forces a correction. If you’re right, it helps create focus. I’ll share how I’ve approached this in the past, both what works and lessons for what didn’t work so well.
Connector Corner: Seamlessly power UiPath Apps, GenAI with prebuilt connectorsDianaGray10
Join us to learn how UiPath Apps can directly and easily interact with prebuilt connectors via Integration Service--including Salesforce, ServiceNow, Open GenAI, and more.
The best part is you can achieve this without building a custom workflow! Say goodbye to the hassle of using separate automations to call APIs. By seamlessly integrating within App Studio, you can now easily streamline your workflow, while gaining direct access to our Connector Catalog of popular applications.
We’ll discuss and demo the benefits of UiPath Apps and connectors including:
Creating a compelling user experience for any software, without the limitations of APIs.
Accelerating the app creation process, saving time and effort
Enjoying high-performance CRUD (create, read, update, delete) operations, for
seamless data management.
Speakers:
Russell Alfeche, Technology Leader, RPA at qBotic and UiPath MVP
Charlie Greenberg, host
Driving Business Innovation: Latest Generative AI Advancements & Success StorySafe Software
Are you ready to revolutionize how you handle data? Join us for a webinar where we’ll bring you up to speed with the latest advancements in Generative AI technology and discover how leveraging FME with tools from giants like Google Gemini, Amazon, and Microsoft OpenAI can supercharge your workflow efficiency.
During the hour, we’ll take you through:
Guest Speaker Segment with Hannah Barrington: Dive into the world of dynamic real estate marketing with Hannah, the Marketing Manager at Workspace Group. Hear firsthand how their team generates engaging descriptions for thousands of office units by integrating diverse data sources—from PDF floorplans to web pages—using FME transformers, like OpenAIVisionConnector and AnthropicVisionConnector. This use case will show you how GenAI can streamline content creation for marketing across the board.
Ollama Use Case: Learn how Scenario Specialist Dmitri Bagh has utilized Ollama within FME to input data, create custom models, and enhance security protocols. This segment will include demos to illustrate the full capabilities of FME in AI-driven processes.
Custom AI Models: Discover how to leverage FME to build personalized AI models using your data. Whether it’s populating a model with local data for added security or integrating public AI tools, find out how FME facilitates a versatile and secure approach to AI.
We’ll wrap up with a live Q&A session where you can engage with our experts on your specific use cases, and learn more about optimizing your data workflows with AI.
This webinar is ideal for professionals seeking to harness the power of AI within their data management systems while ensuring high levels of customization and security. Whether you're a novice or an expert, gain actionable insights and strategies to elevate your data processes. Join us to see how FME and AI can revolutionize how you work with data!
Monitoring and Managing Anomaly Detection on OpenShift.pdfTosin Akinosho
Monitoring and Managing Anomaly Detection on OpenShift
Overview
Dive into the world of anomaly detection on edge devices with our comprehensive hands-on tutorial. This SlideShare presentation will guide you through the entire process, from data collection and model training to edge deployment and real-time monitoring. Perfect for those looking to implement robust anomaly detection systems on resource-constrained IoT/edge devices.
Key Topics Covered
1. Introduction to Anomaly Detection
- Understand the fundamentals of anomaly detection and its importance in identifying unusual behavior or failures in systems.
2. Understanding Edge (IoT)
- Learn about edge computing and IoT, and how they enable real-time data processing and decision-making at the source.
3. What is ArgoCD?
- Discover ArgoCD, a declarative, GitOps continuous delivery tool for Kubernetes, and its role in deploying applications on edge devices.
4. Deployment Using ArgoCD for Edge Devices
- Step-by-step guide on deploying anomaly detection models on edge devices using ArgoCD.
5. Introduction to Apache Kafka and S3
- Explore Apache Kafka for real-time data streaming and Amazon S3 for scalable storage solutions.
6. Viewing Kafka Messages in the Data Lake
- Learn how to view and analyze Kafka messages stored in a data lake for better insights.
7. What is Prometheus?
- Get to know Prometheus, an open-source monitoring and alerting toolkit, and its application in monitoring edge devices.
8. Monitoring Application Metrics with Prometheus
- Detailed instructions on setting up Prometheus to monitor the performance and health of your anomaly detection system.
9. What is Camel K?
- Introduction to Camel K, a lightweight integration framework built on Apache Camel, designed for Kubernetes.
10. Configuring Camel K Integrations for Data Pipelines
- Learn how to configure Camel K for seamless data pipeline integrations in your anomaly detection workflow.
11. What is a Jupyter Notebook?
- Overview of Jupyter Notebooks, an open-source web application for creating and sharing documents with live code, equations, visualizations, and narrative text.
12. Jupyter Notebooks with Code Examples
- Hands-on examples and code snippets in Jupyter Notebooks to help you implement and test anomaly detection models.
Conversational agents, or chatbots, are increasingly used to access all sorts of services using natural language. While open-domain chatbots - like ChatGPT - can converse on any topic, task-oriented chatbots - the focus of this paper - are designed for specific tasks, like booking a flight, obtaining customer support, or setting an appointment. Like any other software, task-oriented chatbots need to be properly tested, usually by defining and executing test scenarios (i.e., sequences of user-chatbot interactions). However, there is currently a lack of methods to quantify the completeness and strength of such test scenarios, which can lead to low-quality tests, and hence to buggy chatbots.
To fill this gap, we propose adapting mutation testing (MuT) for task-oriented chatbots. To this end, we introduce a set of mutation operators that emulate faults in chatbot designs, an architecture that enables MuT on chatbots built using heterogeneous technologies, and a practical realisation as an Eclipse plugin. Moreover, we evaluate the applicability, effectiveness and efficiency of our approach on open-source chatbots, with promising results.
AppSec PNW: Android and iOS Application Security with MobSFAjin Abraham
Mobile Security Framework - MobSF is a free and open source automated mobile application security testing environment designed to help security engineers, researchers, developers, and penetration testers to identify security vulnerabilities, malicious behaviours and privacy concerns in mobile applications using static and dynamic analysis. It supports all the popular mobile application binaries and source code formats built for Android and iOS devices. In addition to automated security assessment, it also offers an interactive testing environment to build and execute scenario based test/fuzz cases against the application.
This talk covers:
Using MobSF for static analysis of mobile applications.
Interactive dynamic security assessment of Android and iOS applications.
Solving Mobile app CTF challenges.
Reverse engineering and runtime analysis of Mobile malware.
How to shift left and integrate MobSF/mobsfscan SAST and DAST in your build pipeline.
zkStudyClub - LatticeFold: A Lattice-based Folding Scheme and its Application...Alex Pruden
Folding is a recent technique for building efficient recursive SNARKs. Several elegant folding protocols have been proposed, such as Nova, Supernova, Hypernova, Protostar, and others. However, all of them rely on an additively homomorphic commitment scheme based on discrete log, and are therefore not post-quantum secure. In this work we present LatticeFold, the first lattice-based folding protocol based on the Module SIS problem. This folding protocol naturally leads to an efficient recursive lattice-based SNARK and an efficient PCD scheme. LatticeFold supports folding low-degree relations, such as R1CS, as well as high-degree relations, such as CCS. The key challenge is to construct a secure folding protocol that works with the Ajtai commitment scheme. The difficulty, is ensuring that extracted witnesses are low norm through many rounds of folding. We present a novel technique using the sumcheck protocol to ensure that extracted witnesses are always low norm no matter how many rounds of folding are used. Our evaluation of the final proof system suggests that it is as performant as Hypernova, while providing post-quantum security.
Paper Link: https://eprint.iacr.org/2024/257
Generating privacy-protected synthetic data using Secludy and MilvusZilliz
During this demo, the founders of Secludy will demonstrate how their system utilizes Milvus to store and manipulate embeddings for generating privacy-protected synthetic data. Their approach not only maintains the confidentiality of the original data but also enhances the utility and scalability of LLMs under privacy constraints. Attendees, including machine learning engineers, data scientists, and data managers, will witness first-hand how Secludy's integration with Milvus empowers organizations to harness the power of LLMs securely and efficiently.
The Microsoft 365 Migration Tutorial For Beginner.pptxoperationspcvita
This presentation will help you understand the power of Microsoft 365. However, we have mentioned every productivity app included in Office 365. Additionally, we have suggested the migration situation related to Office 365 and how we can help you.
You can also read: https://www.systoolsgroup.com/updates/office-365-tenant-to-tenant-migration-step-by-step-complete-guide/
Ivanti’s Patch Tuesday breakdown goes beyond patching your applications and brings you the intelligence and guidance needed to prioritize where to focus your attention first. Catch early analysis on our Ivanti blog, then join industry expert Chris Goettl for the Patch Tuesday Webinar Event. There we’ll do a deep dive into each of the bulletins and give guidance on the risks associated with the newly-identified vulnerabilities.
HCL Notes und Domino Lizenzkostenreduzierung in der Welt von DLAUpanagenda
Webinar Recording: https://www.panagenda.com/webinars/hcl-notes-und-domino-lizenzkostenreduzierung-in-der-welt-von-dlau/
DLAU und die Lizenzen nach dem CCB- und CCX-Modell sind für viele in der HCL-Community seit letztem Jahr ein heißes Thema. Als Notes- oder Domino-Kunde haben Sie vielleicht mit unerwartet hohen Benutzerzahlen und Lizenzgebühren zu kämpfen. Sie fragen sich vielleicht, wie diese neue Art der Lizenzierung funktioniert und welchen Nutzen sie Ihnen bringt. Vor allem wollen Sie sicherlich Ihr Budget einhalten und Kosten sparen, wo immer möglich. Das verstehen wir und wir möchten Ihnen dabei helfen!
Wir erklären Ihnen, wie Sie häufige Konfigurationsprobleme lösen können, die dazu führen können, dass mehr Benutzer gezählt werden als nötig, und wie Sie überflüssige oder ungenutzte Konten identifizieren und entfernen können, um Geld zu sparen. Es gibt auch einige Ansätze, die zu unnötigen Ausgaben führen können, z. B. wenn ein Personendokument anstelle eines Mail-Ins für geteilte Mailboxen verwendet wird. Wir zeigen Ihnen solche Fälle und deren Lösungen. Und natürlich erklären wir Ihnen das neue Lizenzmodell.
Nehmen Sie an diesem Webinar teil, bei dem HCL-Ambassador Marc Thomas und Gastredner Franz Walder Ihnen diese neue Welt näherbringen. Es vermittelt Ihnen die Tools und das Know-how, um den Überblick zu bewahren. Sie werden in der Lage sein, Ihre Kosten durch eine optimierte Domino-Konfiguration zu reduzieren und auch in Zukunft gering zu halten.
Diese Themen werden behandelt
- Reduzierung der Lizenzkosten durch Auffinden und Beheben von Fehlkonfigurationen und überflüssigen Konten
- Wie funktionieren CCB- und CCX-Lizenzen wirklich?
- Verstehen des DLAU-Tools und wie man es am besten nutzt
- Tipps für häufige Problembereiche, wie z. B. Team-Postfächer, Funktions-/Testbenutzer usw.
- Praxisbeispiele und Best Practices zum sofortigen Umsetzen
Fueling AI with Great Data with Airbyte WebinarZilliz
This talk will focus on how to collect data from a variety of sources, leveraging this data for RAG and other GenAI use cases, and finally charting your course to productionalization.
Freshworks Rethinks NoSQL for Rapid Scaling & Cost-EfficiencyScyllaDB
Freshworks creates AI-boosted business software that helps employees work more efficiently and effectively. Managing data across multiple RDBMS and NoSQL databases was already a challenge at their current scale. To prepare for 10X growth, they knew it was time to rethink their database strategy. Learn how they architected a solution that would simplify scaling while keeping costs under control.
"Choosing proper type of scaling", Olena SyrotaFwdays
Imagine an IoT processing system that is already quite mature and production-ready and for which client coverage is growing and scaling and performance aspects are life and death questions. The system has Redis, MongoDB, and stream processing based on ksqldb. In this talk, firstly, we will analyze scaling approaches and then select the proper ones for our system.
How to Interpret Trends in the Kalyan Rajdhani Mix Chart.pdfChart Kalyan
A Mix Chart displays historical data of numbers in a graphical or tabular form. The Kalyan Rajdhani Mix Chart specifically shows the results of a sequence of numbers over different periods.
How to Interpret Trends in the Kalyan Rajdhani Mix Chart.pdf
IAEA, Small and Medium Size Reactors 2009, Kuznetsov
1. Design features to achieve defence-in-depth in small and medium sized
reactors
Vladimir Kuznetsov
International Atomic Energy Agency
Abstract. Broader incorporation of inherent and passive safety design features has become a ‘trademark’ of
many advanced reactor concepts, including several evolutionary designs and nearly all innovative small and
medium sized design concepts. Ensuring adequate defence-in-depth is important for reactors of smaller
output because many of them are being designed to allow more proximity to the user, specifically, when non-
electrical energy products are targeted. Based on the activities recently performed by the International
Atomic Energy Agency, the paper provides a summary description of the design features used to achieve
defence in depth in the innovative concepts of small and medium sized reactors with fast neutron spectrum.
1. Introduction
According to the categorization adopted by the International Atomic Energy Agency (IAEA), small
and medium sized reactors (SMRs) are those with the equivalent electric output less than 700 MW. In
many cases, deployment potential of SMRs is supported by their ability to fill niches in which they
would address market situations different from those of currently operated large-capacity nuclear
power plants — the situations that value more distributed electrical supplies or a better match between
capacity increments and investment capability, or more flexible siting and greater product variety.
Ensuring adequate defence-in-depth is important for reactors of smaller output because many of them
are being designed to allow more proximity to the user, specifically, when non-electrical energy
products are targeted.
Upon the advice and with the support of IAEA member states, the IAEA provides a forum for the
exchange of information by experts and policy makers from industrialized and developing countries
on the technical, economic, environmental, and social aspects of SMR development and
implementation in the 21st century, and makes this information available to all interested Member
States by producing status reports and other publications dedicated to advances in SMR design and
technology development [1,2].
In 2009 IAEA has published a Nuclear Energy Series report titled “Design Features to Achieve
Defence in Depth in Small and Medium Sized Reactors” [3]. The objective of this report is to assist
developers of SMRs in member states in defining consistent defence in depth approaches regarding the
elimination of accident initiators/ prevention of accident consequences by design and the incorporation
of inherent and passive safety features and passive systems into safety design concepts of such
reactors.
The SMRs addresed in [3] represent different reactor lines, intended for different applications, and
targeting different deployment timeframes. The reactor lines considered are pressurized water reactors
— the KLT-40S (35 MW(e), OKBM, Russian Federation), the IRIS (335 MW(e), Westinghouse,
USA), the CAREM-25 (27 MW(e), CNEA, Argentina), the SCOR (630 MW(e), CEA, France), and
the MARS (150 MW(e), University of Rome “La Sapienza”, Italy), targeted for co-generation or
electricity production; pressurized boiling light water cooled heavy water moderated reactors — the
AHWR (BARC, India), targeted for electricity generation with potable water production; high
temperature gas cooled reactors — the GT-MHR (287.5 MW(e), General Atomics, USA), targeted for
1
2. electricity generation and advanced non-electrical applications, including complex cogeneration with
bottoming cycles; sodium cooled and lead cooled fast reactors — the 4S-LMR (50 MW(e), CRIEPI,
Toshiba, Japan) and the SSTAR and the STAR-LM (19.7 and 181 MW(e), both – ANL, USA),
targeted for electricity production or cogeneration; and non conventional very high temperature
designs — the CHTR (100 kW(e), BARC, India), targeted for hydrogen production and other
advanced non-electrical applications. Of those, the addressed fast reactor concepts (4S-LMR, the
SSTAR and the STAR-LM), and the non-coventional design (CHTR) are factory fabricated reactors
capable of more than a decade of operation without on-site refuelling [2].
The descriptions in reference [3] were structured to follow the definitions and recommendations of the
IAEA safety standard NS-R-1 “Safety of the Nuclear Power Plants: Design Requirements” [4], which
provides for the following five levels of defence in depth:
- Level 1 – Prevention of abnormal operation and failure;
- Level 2 - Control of abnormal operation and detection of failure;
- Level 3 - Control of accidents within design basis;
- Level 4 - Control of severe plant conditions, including prevention of accident progression and
mitigation of consequences of severe accidents; and
- Level 5 - Mitigation of radiological consequences of significant release of radioactive materials.
This paper will present general findings of the new IAEA report [3] and provide more details about the
innovative fast-spectrum small reactors without on-site refuelling.
2. Summary of design approaches
2.1. General approach and considerations
An enveloping design approach for all SMR designs addressed is to eliminate as many accident
initiators and/or to prevent as many accident consequences as possible, by design, and then to deal
with the remaining accidents/consequences using plausible combinations of the active and passive
safety systems and consequence prevention measures. This approach is also targeted for Generation IV
energy systems and, to a certain extent it is implemented in some near-term light water reactor designs
of larger capacity, such as the VVER-1000, the AP1000, and the ESBWR [4].
General features of SMRs that, in view of their designers, contribute to a particular effectiveness of the
implementation of inherent and passive safety design features in smaller reactors are:
- Larger surface-to-volume ratio, which facilitates easier decay heat removal, especially with a
single-phase coolant;
- An option to achieve compact primary coolant system design, e.g. integral pool type primary
coolant system, which could contribute to an effective suppression of certain initiating events;
- Reduced core power density, facilitating easy use of many passive features and systems;
- Lower potential hazard that generically results from lower source term owing to lower fuel
inventory, lower non-nuclear energy stored in the reactor, and lower integral decay heat rate.
2.2. Approaches and considerations for sodium cooled and lead cooled fast reactors
All of the considered fast-spectrum SMRs offer design flexibility in setting desired combinations of
reactivity coefficients and effects. This flexibility, coupled with the inherent properties of the
advanced types of fuel, creates a potential to prevent transient overpower accidents; to ensure
increased reactor self-control in a variety of other anticipated transients without scram and
2
3. combinations thereof; and to enable “passive shutdown”1 and passive load following capabilities for a
plant2. Smaller specific core power or relatively tall reactor vessels facilitate the use of natural
convection of a single-phase liquid metal coolant to remove decay heat or even the heat produced in
normal operation (for heavy liquid metal cooled SMRs). For sodium cooled reactors, smaller reactor
size facilitates achieving negative whole-core sodium void reactivity effect. For lead cooled reactors,
there could be a certain size limit to ensure a reliable seismic design [1].
Figure 1 and 2 show general layouts of the 4S-LMR and the SSTAR, respectively.
FIG. 1. Vertical view of the 4S-LMR layout.
Fast-spectrum liquid metal cooled SMR designs are represented by the 4S-LMR concept of a sodium
cooled small reactor without on-site refuelling developed by the Central Research Institute of Electric
Power Industry (CRIEPI) and Toshiba in Japan and by the SSTAR and STAR-LM concepts of small
lead cooled reactors without on-site refuelling developed by the Argonne National Laboratory (ANL)
in the USA. The lead cooled SMR concepts use CO2 as working media in the Brayton cycle power
circuit, and incorporate no intermediate heat transport system. Although essentially different in several
important features, both sodium cooled and lead cooled SMR concepts belong to a family of pool-type
integral design liquid metal cooled fast reactors, and close cooperation between their designers has
been established long ago [3]. Of the two designs, the 4S-LMR is in a more advanced stage, because
for a similar design, different essentially in the type of fuel and named the 4S, the basic design and
1
“Passive shutdown” is used to denote bringing the reactor to a safe low-power state with balanced heat
production and passive heat removal, with no failure to the barriers preventing radioactivity release to the
environment; all relying on the inherent and passive safety features only, with no operator intervention, no active
safety systems being involved, and no external power and water supplies being necessary; and with practically
infinite grace period.
2
It should be noted that such features of liquid metal cooled reactors as passive load following and “passive
shutdown” have been more analyzed in the past for smaller-sized reactors, such as EBR-II of 65 MW(th) or
PRISM of 850 MW(th). However, for sodium and lead cooled fast reactors, there are no reasons that such
features couldn’t be realized in larger reactors with nitride or metallic fuel. Certain analytical studies carried out
in the past provide preliminary proofs of this [5].
3
4. major parts of the system design have been completed [3] A pre-application review by the US NRC
has been initiated in the fall of 2007, and a formal licensing application is scheduled for 2010.
Different from it, both the SSTAR and STAR-LM are at a pre-conceptual stage. It should be noted that
small size and capacity of the fast reactors considered in [3] are, first-of-all, conditioned by the
requirement of operation without on-site refuelling [2] and not by the a priori considerations of
achieving a somewhat higher degree of passive response in accidents.
CONTROL
CLOSURE HEAD ROD
DRIVES
CO2 OUTLET NOZZLE CONTROL
(1 OF 8) ROD GUIDE
CO2 INLET NOZZLE TUBES AND
(1 OF 4) DRIVELINES
THERMAL
Pb-TO-CO2 HEAT BAFFLE
EXCHANGER (1 OF 4)
GUARD
FLOW SHROUD VESSEL
RADIAL REFLECTOR REACTOR
VESSEL
ACTIVE CORE AND
FISSION GAS PLENUM
FLOW DISTRIBUTOR
HEAD
FIG. 2. General view of the SSTAR layout.
Design features of the 4S-LMR and the SSTAR and the STAR-LM contributing to Level 1 of defence
in depth, “Prevention of abnormal operation and failure”, are summarized in Table 1.
TABLE 1. DESIGN FEATURES OF SODIUM COOLED AND LEAD COOLED FAST SMRS
CONTRIBUTING TO LEVEL 1 OF DEFENCE IN DEPTH
# DESIGN FEATURE WHAT IS TARGETED SMR
DESIGNS
1 Low-pressure primary coolant system Low non-nuclear energy stored in the 4S-LMR,
primary coolant system – elimination SSTAR,
of a potential of release of this energy STAR-LM
2 Use of metallic fuel with high thermal High margin to fuel failure 4S-LMR
conductivity (relatively low temperature)
3 Use of nitride fuel with high thermal High margin to fuel failure SSTAR,
conductivity (relatively low temperature) STAR-LM
4 Relatively low linear heat rate of fuel Higher margin to fuel failure 4S-LMR
5 Power control via pump flow rate in the Elimination of an accident with control 4S-LMR
power circuit, with no control rods in the core rod ejection
6 Large negative feedbacks from fast-spectrum Essential prevention or de-rating of the SSTAR,
core plus natural convection of the coolant in initiating events resulting from STAR-LM
all modes, enabling passive load following malfunctioning of the systems or
and “passive shutdown” components, or operator actions that
would otherwise need to be considered
as sources of failure
4
5. # DESIGN FEATURE WHAT IS TARGETED SMR
DESIGNS
7 Low burn-up reactivity swing over long core Elimination of transient overpower SSTAR,
lifetime/ refuelling interval accident due to control rod ejection STAR-LM
8 Elimination of feedback control of moveable Prevention of transient overpower 4S-LMR
reflectors (that compensate for reactivity
changes due to fuel burn-up); a pre-
programmed reflector drive system is used
9 Electromagnetic impulsive force used in the Intrinsic limitation of the speed of 4S-LMR
reflector driving system positive reactivity insertion
10 Intermediate heat transport system Prevention of sodium-water reaction 4S-LMR
11 Pb coolant not reacting chemically with CO2 Elimination of a chemical interaction SSTAR,
working fluid; no intermediate heat transport between the primary coolant and the STAR-LM
system working fluid of a power circuit
12 Natural convection of the coolant plus open - Elimination of loss of flow accidents; SSTAR,
fuel element lattice (large fuel element pitch- STAR-LM
- Prevention of flow blockage accidents
to-diameter ratio)
13 Primary electromagnetic (EM) pumps Prevention of loss of flow 4S-LMR
arranged in two units connected in series,
with each unit capable of taking on one half
of the pump head
14 The reactor vessel enclosed in a guard vessel Prevention of loss of coolant (LOCA) 4S-LMR
to prevent loss of the primary coolant; pool
type design with intermediate heat
exchangers located inside the main reactor
vessel
15 Use of double piping, double tubes and - Prevention of LOCA 4S-LMR
double vessels for the secondary sodium,
- Prevention of sodium-water reaction
including heat transfer tubes of the steam
generator
16 - The reactor vessel enclosed in a guard Prevention of loss of coolant (LOCA) SSTAR,
vessel such that even in the case of primary and its possible consequences STAR-LM
vessel boundary rupture, the faulted level of
lead will always exceed the Pb entrances to
the PB-to-CO2 heat exchangers;
- High boiling point of the Pb coolant
(1740°C), exceeding the point at which
stainless steel core structures melt;
- Pool type design configuration;
- High density of Pb coolant limits void
growth and downward penetration following
a postulated in-vessel heat exchanger tube
rupture.
17 High-reliability system of control of - Maintaining the integrity of stainless SSTAR,
dissolved oxygen potential in the Pb coolant steel cladding in all modes of operation STAR-LM
by preventing corrosion3;
- Prevention of the formation of
corrosion debris with a potential to
block coolant area.
3
Corrosion/erosion is generally a slow and easily detectable process.
5
6. Low-pressure primary coolant system, securing low non-nuclear energy stored in the primary coolant
system is a common feature of all liquid metal cooled reactors, irrespective of their size and capacity.
In addition to it, like many innovative liquid metal cooled reactors of a variety of capacities and sizes,
all SMRs considered in this section rely on advanced fuel designs with high thermal conductivity,
ensuring increased margins to fuel failure.
The lead cooled SSTAR and STAR-LM reactors incorporate optimum sets of reactivity feedbacks,
provided by design and contributing to the elimination of transient overpower, as well as to the
prevention or de-rating of the initiating events resulting from malfunctioning of systems or operator
actions. Specifically, the designers of the SSTAR and STAR-LM mention the so-called “passive
shutdown” capability of their reactors as provided by design.
The sodium cooled 4S-LMR provides for power control via pump flow rate in the power circuit, with
no control rods in the core, and for pre-programmable movement of axial reflectors with no feedback
control, contributing to burn-up reactivity compensation. Both of these features contribute to the
prevention of transient overpower accidents.
To prevent sodium-water reaction, the 4S-LMR incorporates intermediate heat transport system, like
most of the sodium cooled fast reactors. As the CO2 is used as a working medium in the power circuits
of the SSTAR and STAR-LM, which does not react chemically with Pb, these reactors do not
incorporate intermediate transport system.
Natural convection is used in the SSTAR and STAR-LM to remove heat under normal operation,
eliminating loss of flow accidents. De-rating of loss of flow in the 4S-LMR is achieved by a scheme
with two electromagnetic pumps connected in series.
Both sodium and lead cooled SMRs incorporate guard vessel to prevent LOCA; the 4S-LMR also
incorporates double piping and double vessels for secondary sodium, including heat transfer tubes of
the steam generator.
Finally, reliable system of corrosion control is assumed to be provided for the SSTAR and STAR-LM
to maintain the integrity of stainless steel claddings and to prevent the formation of the corrosion
debris with a potential of coolant area blockage. For these reactors it is important to maintain the
oxygen potential in the correct regime to prevent the formation of PbO, which needs to be avoided.
There could also be corrosion debris such as Fe that migrates into the coolant where it forms iron
oxide that should be filtered out.
Design features of the 4S-LMR and the SSTAR and the STAR-LM contributing to Level 2 of defence
in depth, “Prevention of abnormal operation and failure”, are summarized in Table 2.
TABLE 2. DESIGN FEATURES OF SODIUM COOLED AND LEAD COOLED FAST SMRS
CONTRIBUTING TO LEVEL 2 OF DEFENCE IN DEPTH
# DESIGN FEATURE WHAT IS TARGETED SMR DESIGNS
1 All-negative temperature reactivity Increased self-control of 4S-LMR
coefficients abnormal operation
2 Large negative feedbacks in fast Increased self-control of SSTAR, STAR-LM
spectrum core; natural convection of abnormal operation, including
the coolant in all modes; physical passive load following and
properties of Pb coolant and nitride “passive shutdown”
fuel with high heat conductivity
3 Large thermal inertia of the coolant Slow pace of the transients due 4S-LMR, SSTAR,
and the shielding structure to abnormal operation STAR-LM
4 Sodium leak detection system in the Enhanced detection of failure of 4S-LMR
heat transfer tubes of the steam the secondary sodium boundary
generator, capable of detecting both
inner and outer tube failures
5 Two redundant power monitoring Enhanced control of abnormal 4S-LMR
systems; balance of plant temperature operation and detection of
6
7. # DESIGN FEATURE WHAT IS TARGETED SMR DESIGNS
monitoring system; electromagnetic failure
pump performance monitoring system;
cover gas radioactivity monitoring
system, etc.
6 System of monitoring of the dissolved Control of the SSTAR, STAR-LM
oxygen potential in the Pb coolant corrosion/erosion processes of
stainless steel claddings in Pb
flow and detection of failures
7 Independent and redundant shutdown Reactor shutdown All designs
systems (see Table 30 for details)
For Level 2 of defence in depth, “Control of abnormal operation and prevention of failure”, the
contributions come from large thermal inertia of the primary coolant system and reactor internals,
resulting in a slow progress of transients, and from optimum negative feedbacks, provided by design
and ensuring high-degree of reactor self-control. Specifically, passive load following and “passive
shutdown” capability are mentioned for the SSTAR and STAR-LM. Monitoring and detection systems
are other important contributors. Finally, independent and redundant active or passive shutdown
systems are available for the cases when all other measures of control and prevention turn out to be
ineffective.
Design features of the 4S-LMR and the SSTAR and the STAR-LM contributing to Level 3 of defence
in depth, “Prevention of abnormal operation and failure”, are summarized in Table 3.
TABLE 3. DESIGN FEATURES OF SODIUM COOLED AND LEAD COOLED FAST SMRS
CONTRIBUTING TO LEVEL 3 OF DEFENCE IN DEPTH
# DESIGN FEATURE WHAT IS TARGETED SMR DESIGNS
1 Use of metallic fuel with high thermal High margin to fuel failure; larger 4S-LMR
conductivity (relatively low grace period
temperature)
2 Use of nitride fuel with high thermal High margin to fuel failure; larger SSTAR, STAR-LM
conductivity (relatively low grace period
temperature)
3 Relatively low linear heat rate of fuel Higher margin to fuel failure; larger 4S-LMR
grace period
4 All-negative temperature reactivity Increased reactor self-control in design 4S-LMR
coefficients basis accidents
5 Large negative feedbacks from fast Increased self-control of the reactor in SSTAR, STAR-LM
spectrum core, natural convection of design basis accidents, including
the coolant in all modes, physical passive load following and “passive
properties of Pb coolant and nitride shutdown” (in the case of a failure of
fuel with high heat conductivity both scram systems)
6 Negative whole-core void worth Prevention of design basis accidents 4S-LMR
propagation into beyond design basis
conditions (due to coolant boiling or
loss)
7 - Very high boiling point of Pb Prevention of core void as the SSTAR, STAR-LM
coolant (1740°C); extension of design basis accidents;
securing of normal heat removal path
- Escape path for gas/void to reach
through Pb/CO2 heat exchangers in
free surface provided by design;
DBA
- The reactor vessel is enclosed in a
guard vessel such that even in the
case of primary vessel boundary
7
8. # DESIGN FEATURE WHAT IS TARGETED SMR DESIGNS
rupture, the faulted level of lead will
always exceed the Pb entrances to the
PB-to-CO2 heat exchangers.
8 Large specific (per unit of power) Increased grace period 4S-LMR, SSTAR,
inventory of the primary coolant STAR-LM
9 Effective radial expansion of the core Increased reactor self-control in design 4S-LMR, SSTAR,
(negative feedback), provided by basis accidents; prevention of DBA STAR-LM
design propagation into beyond design basis
conditions
10 Low pressure loss in the core region, Increased level of natural circulation to 4S-LMR
provided by design remove decay heat from the core
11 A combined system of Increased grace period in the case of 4S-LMR
electromagnetic pumps and pump failure
synchronous motors (SM), ensuring
favourable flow coast-down
characteristics
12 Natural convection of the coolant in Increased reliability of heat removal by SSTAR, STAR-LM
all modes of operation plus open fuel natural convection of the coolant via
element lattice (large fuel element Pb-CO2 heat exchangers and, in the
pitch-to-diameter ratio) case of their failure, by natural
convection based decay heat removal
systems RVACS and DRACS
13 Two independent systems of reactor Reactor shutdown 4S-LMR
shutdown, each capable of shutting
down the reactor by:
- A drop of several sectors of the
reflector; or
- Gravity-driven insertion of the
ultimate shutdown rod.
14 Two independent and redundant Reactor shutdown4 SSTAR, STAR-LM
active safety grade shutdown systems
15 Redundant and diverse passive Increased reliability of decay heat 4S-LMR
auxiliary cooling systems (RVACS removal from the core
and IRACS or PRACS), both using
draught of environmental air as an
ultimate heat sink
16 Two or more safety grade Increased reliability of decay heat SSTAR, STAR-LM
independent Direct Reactor Auxiliary removal from the core (especially,
Cooling System (DRACS) providing when the normal path via Pb-CO2 heat
independent paths for decay heat exchangers becomes unavailable)
removal. The reactor vessel auxiliary
cooling system (RVACS), if present,
will be a single safety grade decay
heat removal system. If RVACS and
DRACS are both present, this
provides even a greater diversity.
However, if DRACS are effective, the
role of RVACS would be reduced.
All systems will use natural draught
4
It is noted that the operation of these systems may actually be unnecessary because the inherent and passive
features are in any case capable to ensure a “passive shutdown”.
8
9. # DESIGN FEATURE WHAT IS TARGETED SMR DESIGNS
of air as an ultimate heat sink.
17 Use of double piping, double tubes Prevention of steam generator tube 4S-LMR
and double vessels for the secondary rupture, sodium-water reaction, and
sodium, including heat transfer tubes pressure increase in the intermediate
of the steam generator heat transport system
18 Passive pressure relief from primary Protection of the reactor vessel and SSTAR, STAR-LM
coolant system enclosure from over-pressurization in
the case when one or more of the in-
vessel Pb-to-CO2 heat exchanger tubes
fail
For Level 3 of defence in depth, “Control of accidents within design basis”, the contribution comes for
the following main groups of design features:
(1) Inherent safety features, highlighted in positions 1–8 of Table 3. In addition to the features already
discussed in conjunction with defence in depth levels 1 and 2, it is important to note negative whole-
core void worth provided by design in the 4S-LMR and inherent features of the lead cooled SSTAR
and STAR-LM, practically eliminating the option of coolant boiling or gas bubbles arriving to the core
(preventing the propagation of a design basis accident into a severe accident with transient
overpower);
(2) By-design provisions for certain passive mechanisms such as radial expansion or enhanced level of
natural convection in the primary coolant system, highlighted in positions 9–12 of Table 3;
(3) Two independent systems of reactor shutdown, provided in each design; see positions 13–14 of
Table 3. Those operate based on gravity in the 4S-LMR, while in the SSTAR and the STAR-LM both
systems are active and safety grade. For the SSTAR and STAR-LM, it is mentioned that the operation
of these systems may actually be unnecessary because the inherent and passive features are in any case
capable to ensure a “passive shutdown” of the reactor;
(4) Not less than two redundant and diverse passive decay heat removal systems in each design, with
some of them, possibly, providing several passive decay heat removal paths, and all using natural
draught of air as an ultimate heat sink, positions 15–16 of Table 3;
(5) Special design features provided to prevent or mitigate the effects of pressurized medium from the
power circuit getting into the primary circuit; positions 17–18 of Table 3.
The 4S-LMR incorporates no active safety systems. However, there are several active systems
providing normal operation of the reactor at rated or de-rated power, e.g., electromagnetic pumps
providing forced convention of sodium coolant to remove core heat, or burn-up reactivity
compensation system based on slow upward movement of the reflector, using advanced pre-
programmed drive mechanism. These systems can contribute to performing safety functions in certain
accident scenarios. No information was provided on which systems of the 4S-LMR are safety grade.
All passive and active safety systems in the SSTAR and the STAR-LM are assumed to be safety
grade.
The design feature contributing to Level 4 of defence in depth, “Control of severe plant conditions,
including prevention of accident progression and mitigation of consequences of severe accidents” fit
in the following main groups; see Table 4:
(1) The inherent safety features contributing to prevention of core melting;
(2) Redundant and diverse passive decay heat removal systems with natural draught of air used as an
ultimate heat sink, discussed in more detail in conjunction with Level 3 of defence in depth;
(3) Inherent and passive design features for the prevention of recriticality. Those include an effective
mechanism of fuel carry-over from the core in the case of fuel element cladding failure (4S-LMR) and
9
10. high density of the Pb coolant securing that molten fuel is moved to the upper free level of lead
(SSTAR and STAR-LM);
(4) Guard vessels in addition to the main vessels, for all designs, and double piping for the 4S-LMR;
(5) The containment and reactor location in a concrete silo below the ground level, for all designs
considered.
For Level 5 of defence in depth, “Mitigation of radiological consequences of significant release of
radioactive materials”, the designers of the 4S-LMR foresee no measures needed beyond the plant
boundary in response to any severe accidents and combinations thereof, even in the case when there is
no operator intervention, no emergency team actions, and no external power and water supply. The
designers of the SSTAR and STAR-LM take a more conservative approach, suggesting that standard
measures may still be applicable but within the exclusion zone reduced against that of the present day
reactors.
2.3. Reduced off-site emergency planning
The designers of most of the SMRs addressed in reference [3] foresee that safety design features
contributing to defence in depth levels 1–4 could be sufficient to meet the objective of the defence in
depth level 5 “Mitigation of radiological consequences of significant release of radioactive materials”,
i.e., that the emergency planning measures outside the plant boundary might be reduced or even not
needed at all. The design features of the SMRs indicated to make a contribution directly to Level 5 of
defence in depth are lower fuel inventory, lower non-nuclear energy stored in the reactor, and lower
integral decay heat rate of a smaller reactor as compared to the large-capacity one
Level 1 Defence in Depth : prevention of abnormal operation and system failure
Events
F managed by Events
Lev 2 of D.I.D managed by
Lev 3 of D.I.D
Initiating Events are
caused by Failures of
the Level 1 of D.I.D
Events
managed by
Lev 4 of D.I.D
AOO
UNACCEPTABLE DOMAIN
10 -2
AC
-6
10
SPC
10 -7
C
AOO – abnormal operation occurrences AC – accidental conditions
F – frequency C – consequences SPC – severe plant conditions
FIG. 3. Quantitative safety goal and correlation of levels of defence in depth [8].
As a desired or possible feature, reduced off-site emergency planning is mentioned in the Technology
Goals of the Generation IV International Forum, in the user requirements of the IAEA’s International
Project on Innovative Reactors and Nuclear Fuel Cycles (INPRO) [6], and in the recommendations of
the International Nuclear Safety Advisory Group (INSAG-12) [7], with a caution that full elimination
of off-site emergency planning may be difficult to achieve or with a recommendation that Level 5 of
defence in depth still needs to be kept, notwithstanding its possibly decreased role. Achieving the goal
of a reduced off-site emergency planning would require both, development of a methodology to prove
that such reduction is possible in the specific case of a plant design, and adjustment of the existing
regulations.
10
11. Risk-informed approach to reactor qualification and licensing could facilitate licensing with reduced
off-site emergency planning for smaller reactors, once it gets established5. Within the deterministic
safety approach it might be very difficult to justify reduced emergency planning in view of a
prescribed consideration of a postulated severe accident with radioactivity release to the environment
owing to a common cause failure. Probabilistic safety assessment (PSA), as a supplement to the
deterministic approach, might help justify very low core damage frequency (CDF) or large early
release frequency (LERF), but it does not address the consequences and, therefore, does not provide
for assessment of the source terms.
Risk-informed approach that introduces quantitative safety goals, based on the probability-
consequences curve could help solve the dilemma by providing for a quantitative measure for the
consequences of severe accidents and by applying a rational technical and non-prescriptive basis to
define a severe accident. An example of such approach is in provided in the IAEA-TECDOC-1570
[8], see Fig. 3. As of today,such an approach is not yet established as an IAEA safety standard.
3. Conclusion.
For all SMRs design concepts addressed in reference [3], the designers expect that prototype or first-
of-a-kind plants with their respective SMRs would be licensed according to the currently emplaced
regulatory norms and practices in member states. Further advancement of regulatory norms toward
risk-informed approach could then facilitate design improvements in the next plants and, specifically,
help justify reduced off-site emergency planning. Further revisions of the IAEA safety standards
toward a technology-neutral approach6 could be of value to facilitate design development and safety
qualification of non water cooled SMRs, including small fast reactors, such as the 4S-LMR, the
SSTAR and STAR-LM.
REFERENCES
[1] INTERNATIONAL ATOMIC ENERGY AGENCY, Status of Innovative Small and Medium Sized
Reactor Designs 2005: Reactors with Conventional Refuelling Schemes, IAEA-TECDOC-1485,
Vienna (2006).
[2] INTERNATIONAL ATOMIC ENERGY AGENCY, Status of Small Reactor Designs without On-
site Refuelling, IAEA-TECDOC-1536, Vienna (2007).
[3] INTERNATIONAL ATOMIC ENERGY AGENCY, Designs Features to Achieve Defence in Depth
in Small and Medium Sized Reactors, IAEA Nuclear Energy Series Report NP-T-2.2, Vienna (2009).
[4] INTERNATIONAL ATOMIC ENERGY AGENCY, Status of Advanced Light Water Reactor
Designs 2004, IAEA-TECDOC-1391 (2004)
[5] P. ROYL et al., "Performance of metal and oxide fuel cores during accidents in large liquid metal
cooled reactor", Nuclear Technology, Vol. 97. 198-211; Feb 1992.
[6] INTERNATIONAL ATOMIC ENERGY AGENCY, Methodology for the assessment of innovative
nuclear reactors and fuel cycles – Report of Phase 1B (first part) of the International Project on
Innovative Reactors and Fuel Cycles (INPRO), IAEA-TECDOC-1434, Vienna (2004).
[7] INTERNATIONAL ATOMIC ENERGY AGENCY, ‘Basic Safety Principles for Nuclear Power
Plants’: 75-INSAG-3 rev. 1 / INSAG-12, Vienna (1999).
[8] INTERNATIONAL ATOMIC ENERGY AGENCY, Proposal for a Technology-Neutral Safety
Approach for New reactor Designs, IAEA-TECDOC-1570 (2007).
5
Risk-informed regulations for beyond design basis accidents are already emplaced in some member states, e.g., Argentina.
6
National regulations is some member states are already technology-neutral; the examples are the United Kingdom or the
Russian Federation
11