India’s Millennium Development Goals Eradicate extreme Poverty and Hunger. Achieve universal primary education. Promote gender equality and empower women. Reduce child mortality. Improve maternal health. Combat HIV/AIDS ,malaria and other diseases. Ensure environmental sustainability. Develop a global partnership for development. For every goal mentioned above except the last one is linked with Electricity
The needs…. The 11th Plan envisaged to add 79000 MWe to the generating capacity. According to World Bank 40% of Indians are without Electricity. Black outs in the cities are common. 1.15 Lakh villages remain un-electrified. This is in-spite of the fact, that India is the fifth largest producer of electricity in the world.
Energy Requirements (MToE)35003000 2001/022500 2006/072000 2011/121500 2016/17 2021/221000 2026/27 500 2031/32 0 BAU REN NUC EFF HYB LG HG HHYB The above Calculation was done by TERI using software MARKAL.
What are the energy options? COAL Coal (Thermal Power) will account for about 45-55 %. India is third largest producer and third largest consumer of coal. We will have to import coal= 1176 MToE (imports) by 2031 costing-Rs 400,000 Crores. With rising demands of coal, Prices will Shoot up.
Problems related with COAL Transmission costs. Technology to dig deeper than 1200 M is being explored. The production per labour of coal is quite low in comparison to other countries like USA and Australia. Coal is also used in Steel Industry. GHG emissions. So, it is required to be used Judiciously.
Hydropower Immense potential exists. (150,000 MWe). Only 16 % is being utilized. Bigger potential in North East. Not easy to construct DAMS due to large submergence of land and problems related to environmental and rehabilitation problems.
Wind India is the fourth Largest Producer of Wind power. About 5000 MWe. Uncertain power…..coupled with voltage/frequency fluctuations. Can only be installed in coastal areas. Can not be transmitted economically.
SOLAR POWER Photovoltaic cells have low efficiency of about 17%. Can only be utilized when Sun Shines for days. Vast potential exists (20,000 MWe). But due to high cost of PV cells, it is not economical. Mostly dependent on Government Subsidies.
Natural Gas According to Oil and Gas Journal, India had approximately 38 trillion cubic feet (Tcf) of proven natural gas reserves as of January 2010. The Energy Information Administration estimates that India produced approximately 1.4 Tcf of natural gas in 2009 , a 20 percent increase over 2008 production levels. In 2009, India consumed roughly 1.8 Tcf of natural gas , almost 300 billion cubic feet (Bcf) more than in 2008, according to EIA estimates. Natural gas demand is expected to grow considerably,largely driven by demand in the power sector. diversification and overall energy security. Despite the steady increase in India’s natural gas production, demand has outstripped supply and the country has been a net importer of natural gas since 2004 . India’s net imports reached an estimated 445 Bcf in 2009.
This concludes…. In spite of coal amounting to be used as primary source of power it’s % share can be around 55. India will have to import coal, natural gas, crude oil etc to meet the energy needs. Solar power and wind power do have their own limitations, but are being developed at a faster rate. Energy is a must if we envisage a growth rate of 9-10 %.
This concludes… In order to achieve the millennium goals of development we need to tap other sources of energy which are Clean, Green, economically viable and proven. Nuclear Power is a viable option owing to good reserves of Uranium and Thorium in the country.
The current scenario. Nuclear, 4120, 3% Renewables, 13242, 9% Hydro, 36917, 25% Thermal, 96295, 63%Source: India 2010 (Data as on 31/07/2009) Total MWE:150574MWe
Atomic Energy The most reliable source of energy. It is happening in the Sun. Unfortunately, the world came to know of it’s power during the Nuclear Holocaust of Hiroshima and Nagasaki. This is the cause we have fear in our minds from Nuclear Energy.
The Atom The word atom is borrowed from the Greek language. The prefix "a" means "not" and the Greek word "tomos" means "cuttable." So the literal translation of the word "atom" from Greek to English is "uncuttable," meaning it was believed to be the smallest possible unit of matter (matter is anything that takes up space).
Atomic Energy Nucleus of the atom consists of Neutrons and Protons bounded together. When two lighter nuclei are combined energy is liberated. Hydrogen is continuously changing into Helium in the SUN giving tremendous amount of energy. Similarly when a heavy Nucleus is broken energy is released. Fusion and Fission.
Controlled Chain Reaction This is what happens in a Nuclear Reactor. With every fission two or three neutrons are produced which may cause further fission. To control the Rate of fission, Neutron absorbing materials are placed in a nuclear reactor.
1. Calandria Shell 2. Over Pressure Relief Device 3. Shut Down system 4. ShutDown system 5. Moderator Inlet 6. Moderator Outlet 7. Vent Pipe 8. CoolantChannel Assembly 9. End Shield 10. End Shield Support Structure ass’y 11. MainShell Assembly 12. Tube Sheet F/M Side 13. Tube Sheet Cal. Side 14. LatticeTube 15. End Shield Support Plate 16. End Shield Cooling Inlet Pipes 17. EndFitting Assembly 18. Feeder Pipes 19. Outer Shell 20. Support Lug
Reactor Types Neutron Energy Purpose – Thermal – Research – Fast – Power Moderator – Marine – Heavy Water – Light Water Fuel Distribution – Graphite – Homogeneous – Organic – Heterogeneous Coolant Enrichment Level – Heavy Water – Natural – Light Water – Sodium – Low Enrichment – Gas – High Enrichment
Pressurised Heavy Water Reactors The Nuclear Power Program in India at present is based mainly on a series of Pressurized Heavy Water Reactors (PHWRs). Starting from Rajasthan Atomic Power Station, comprising of two units of 200 MWe Canadian designed PHWRs in 1973, the program has come a long way with 15 PHWR units (which includes 2 units of 540 MWe PHWRs) in operation and 3 units under construction. Narora Atomic Power Station commissioned in 1991 marked major indigenization and standardization of PHWR designs. The current design plans include 700 MWe capacity units.
How Electricity is produced? The Flow Diagram of PHWR
PHWRs The Indian PHWR design has evolved through a series of improvements over the years in progressive projects. evolution in technology. feedback from experience in India and abroad, including lessons learnt from incidents and their precursors. evolving regulatory requirements and cost considerations. Valuable experience gained in design, manufacture, construction, operation, maintenance and safety regulation has enabled continual evolution, improvement and refinement in the PHWR concept in a progressive manner.
Design Data1 Rated Output (Thermal) 756 MW2 Rated Output (Electrical) 220 MWe3 Fuel UO24 Moderator Heavy Water5 Coolant Heavy Water6 Type Hor.Press.Tube7 Calandria SS 304L8 End Shield SS 304 L
Indian Nuclear Stations & Projects 3900 MWe 3380 MWe
Safety in PHWRs (Why safety?) Safety is required in every human activity, as every human activity can be related to a specific hazard. (Driving, Flying Planes, Industry). In a fertilizer plant Ammonia Gas is the hazard. No activity of ours should cause human beings to come to harm in particular and environment in general. Here radiation is the hazard. To protect the occupational workers and public from this hazard measures of safety have been undertaken.
How we are safe? Source of radiation is contained in a container and it is covered by many layers of water and structures. These are called barriers. It can also be termed as inherent Safety.
Barriers SC PC CV CT PT Calandri a ShellUranium Fuel
Safety in PHWR In all the states of the reactor we need to cool the core. When Reactor is operating it is cooled by PCPs When Reactor is in Shutdown state it is cooled down by S/D Pump.
Power Supply System III IV TRANSFORMEBattery R II GRID PMG I 415 V AC 415 V AC 250 V DC D 6.6.KV AC
What Can Possibly Go Wrong?? Before we plan for safety we must analyse what are the hazards and what risks are associated? This is called Hazard analysis. This is done before and during design of the systems, so that risks are eliminated and one is free from dangers posed by hazards. Ask….the audience….!!!!
We should be safe when… Core cooling is affected. Power supply failure. Reactor power goes up. Earthquake occurs. Cyclones occur Tsunamis /Floods occur. Terrorists Strike. Fire breaks out. Containment Pressure and temperature goes up.
Shut Down Systems (Fail Safe design) PSS GAS TANKS Borated WaterReactor SSS
Safety in PHWRs Philosophy of Defense in depth. – Prevent Accidents – Mitigate their impacts if they happen. – Ready Emergency Plan. Multiple functional and/or engineered barriers to preclude Single Failures and prevent release of radioactive materials. Incorporation of large Design Margins where possible. High Quality in design and manufacture. Operation within design limits. Testing/inspection to maintain Design
Defense In Depth Objective Prevention of abnormal operation and failuresLevel 1 Means Conservative design and high quality in construction and operation Objective Control of abnormal operation and detection of failuresLevel 2 Control, limiting and protection system and other Prevention Means surveillance features of accidentLevel 3 Objective Control of accidents within the design basis Prevention of severe core Means Engineered safety features and accident damage procedures Control of severe plant conditions, including prevention of ObjectiveLevel 4 accident progression and mitigation of the consequences of severe accidents Means Complementary measures and accident managementLevel 5 Objective Mitigation of radiological consequences of significant releases of radioactive materials Means Off-site emergency response
Objectives of Safety (Nuclear) The fundamental objective of safety is to take all practicable measures to:(a) prevent accidents; and(b) mitigate the consequences of accidents, should they occur, so that: (i) likelihood of accidents with serious radiological consequences is extremely low, and (ii) radiological consequences would be below acceptable limits in case an accident occurs.
Safety Functions In order to meet the objectives of safety either we can design every structure, system or component (SSC)adopting the most stringent codes and standards available. Or the systems can be graded according to their safety functions. The function which a SSC performs which ensures safety is called a safety function. Systems have been graded as per the safety functions into different classes.
Safety Function One function of the SSC may be to prevent reactor power going awry. Another function may be to keep the Reactor Shutdown till demanded by the operator. Another may be to Shutdown the reactor if the Loss of coolant of the reactor occurs. One may be to remove decay heat after a failure of PHT boundary.
Safety Design Principles It has been ensured that structures,systems and components having a bearing on reactor safety are designed to meet stringent performance and reliability requirements. The quality requirements for design,fabrication,construction and inspection for these systems is of high order.They are designed to conform to codes and standards which demand the highest quality. Designed to work under high temperature and pressure conditions. Adequate redundancy.Triplicated channels.Specified down time. Fail safe. Testing of systems.
Safety Classes The systems have been graded with regard to their importance to safety and reliability. These SSCs have been graded as per their safety functions. Safety Class:1 Highest safety class. (ASME SEC III NB). Includes (Rx S/D systems and PHT) Safety Class:2 are required for those to prevent escalation of AOOs to accidents.(Feed water,ECCS,Containments).
Safety Classes. Safety Class 3: Supports Class 2 and 3. (PW Cooling system,IDCTs,Air supply system,Purification) Safety Class 4: Do not fall in above classes. (WMP, UGP,SB, Ventilation system)
Seismic Classification OBE SSE Items OBE items SSE Rx S/D Steam and Systems Feed water Class 1,2,3 are system Calandria Condenser generally SSE PHT(Main) CCW system Containment Chilled water Spent Fuel Off site power Storage bay system Rx decay heat removal system DGs
Safety from Earthquake Designed for automatic Shutdown when Earthquake occurs of a required magnitude. Designed for Richter Scale about 7.
Loss of Coolant Scenario Emergency core cooling system High pressure Heavy water Injection. Intermediate pressure Light water injection Low pressure Light water injection. Long Term Recirculation. Back up available. Fire water)
TYPE-1 HEAVY WATER INJECTION AT < 55Kg/cm2 GAS Heavy Water ECC INJECTION IN MV-15 E BOTH INLET HEADER MV-16 E E E E E MV-9 MV-10 MV-11 MV-12 MV- 5 MV- 6 MV- 3 MV- 4E E E E E HL CL CR HR
TMI-2 Accident Progression Loss of feed water to steam generator lead to rise in reactor pressure and Reactor got shutdown on reactor pressure high . Pressurizer acts to control reactor pressure by opening of Pilot-operated relief valve (PORV) and got stuck open. Relief Valve should have closed but stayed open. Signal to operator failed to show that valve is stuck open . Primary water was lost continuously through open valve into the containment. Steam generators boil dry, resulting in loss of heat sink . ECC started automatically but operator switched off the ECC as situation was not properly diagnosed
Lessons Learnt from TMI-2 Modification in the area of design, operating practices , emergency preparedness , QA and training & qualification of operation personnel. Reliability of Auxiliary Boiler Feed Water Supply. Augmentation in the feed capacity for inventory control of PHT system under off-site power failure conditions. Capability for remote isolation of moderator HXers to check spread of radioactivity. A high-pressure ECCS was incorporated in the units under construction. Back fitting of such system for operating units was also worked out for subsequent implementation. Reliability of ECCS in these operating units was enhanced by provision of local air receivers for each air-operated valve. Emergency operating procedures (EOPs) were developed for a large number of PIEs to handle emergency/accident conditions.
Chernobyl (April 1986)•Reactor#4 was undergoing a Test Plan whether the turbines couldproduce sufficient energy to keep the coolant pumps running in theevent of a loss of power until the emergency diesel generator wasactivated•Safety systems were deliberately switched off•The reactor had to be powered down to 25% of it’s capacity, thisprocedure did not occur and the reactor power fell to less than 1%allowing the concentration of xenon-135 to rise.•The workers continued the test, and in order to control the risinglevels of xenon-135, the control rods were pulled out.•The experiment involved shutting down the coolant pumps, whichcaused the coolant to rapidly heat up and boil.•Pockets of steam formed in the coolant lines.
Chernobyl Accident Progression Due to positive void coefficient at this low power range, the power level went up. All control rods were ordered to be inserted. As the rods were inserted, they became deformed and stuck. The nuclear reaction could not be stopped and power increased. The rods melted and the steam pressure caused an explosion, which blew a hole in the roof. A graphite fire also resulted from the explosion. •Reactor had partial containment , which allowed the radiation to escape.
Lessons from Chernobyl Reviews following the Chernobyl Accident(1986) re- emphasized the necessity for adhering to the already established principles of reactor safety design and operation. Figure out the need for well coordinated plans and organization for on-site & off-site emergencies that may arise from nuclear accidents. Re-emphasized the need for maintaining `safety culture‘ in the conduct of operations at the station. Actions were taken to reinforce these aspects in operating principles and practices . The plans and organization for on-site and off-site emergencies were also strengthened for all the power stations.
Fukushima Daichii Earthquake of magnitude 9.0 on 11 March 2011 followed by Tsunami of 14 meter high waves-beyond the design basis. All operating plants at the affected area automatically shutdown-Terminating chain reaction. Reactor core Cooling–Continued for one hour,got incapacitated after tsunami- caused fuel overheating-Metal Water Reaction-Hydrogen Generation-Explosion inside the outer Building.
Fukushima Daichii No nuclear explosion. Hydrogen generated led to explosion damaging the outer concrete building. The reactor pressure vessels integrity unaffected. No death on account of radiation exposure.
Lessons From Fukushima Think and make allowances for Beyond design basis accidents. NPCIL formed core groups to analyse the present facilities to deal with such situations. The recommendations of the core group are being incorporated.
“Nuclear Power is better than No Power” Thanks…..!!!!