Everyone is familiar with Einstein’s formula E = mc2 , which is more accurately expressed as: This formula states that mass and energy are two forms of the same reality that can be interchanged under certain conditions, The total mass of a nucleus is thus lower than the sum of the masses of all the protons and all the neutrons that make it up, and the difference in mass is the binding energy of the nucleus The most stable combination of nucleons happens to be a medium-sized nucleus. This means that if two light nuclei can be fused to form a medium-sized nucleus, some binding energy will be released, and if a heavy nucleus can be split into two medium-sized nuclei, this energy can also be harnessed. These two phenomena are known respectively as thermonuclear fusion and fission.
Fission energy released from 1 Kg of U 235 is equivalent to combusion of 3000 MT of coal or 1000 cu m of oil.
Fission energy released from 1 Kg of U 235 is equivalent to combusion of 3000 MT of coal or 1000 cu m of oil.
If the neutron travels very fast it may not strike another U-235 nuclei and the chain reaction may not be sustained. Hence a moderator is used to slow down the neutrons. Moderators used are Light water Heavy Water Graphite.
Control rods are concentrated neutron absorbers which can be moved into or out of the core to change the rate of fissioning in the reactor. Rod insertion adds neutron poisons to the core area, which makes fewer neutrons available to cause fission. This causes the fission rate to decrease, which results in a reduction in heat production and power. Pulling the control rods out of the core removes poisons from the core area allowing more neutrons to cause fissions and increasing reactor power and heat production.
Low-level waste includes slightly contaminated clothing and items that comes from places such as nuclear medicine wards in hospitals, research laboratories and nuclear plants. Low-level waste contains only small amounts of radioactivity that decays away in hours or days. After the radioactivity has decayed, low-level waste can be treated like ordinary garbage. Intermediate-level wastes mostly come from the nuclear industry. They include used reactor components and contaminated materials from reactor decommissioning. Typically these wastes are embedded in concrete for disposal and buried. High-level waste generally describes spent fuel from nuclear reactors. Spent nuclear fuel from nuclear power plants is initially stored in large water-filled pools. The water provides shielding from the radiation and cooling to remove the heat, which continues to be generated by the radioactive material in the spent fuel. After several years, when the radioactivity and its associated heat have diminished, the fuel is transferred to medium-term storage near the nuclear power plants. The nuclear industry is evaluating long-term storage of high-level waste. While spent fuel is safely stored at nuclear plant sites today, the storage facilities were never intended for permanent storage. Countries operating nuclear power reactors are conducting extensive studies on how high-level wastes should be disposed. Research indicates the ideal permanent storage disposal is in deep underground caverns in stable geological formations.
Becquerel : Number of disintegration/decay of radioactive atoms per second Gray : Quantity of radioactivity absorbed per unit mass of body (Joule/kg) Sievet :Takes into account biological effects of different kinds of radiation.Gray is multiplied by radiation type dependent factor to get Sievet.
Nuclear Reactors - The heart of the Nuclear plant is a specially designed equipment to initiate , maintain and control a nuclear fission chain reaction so that the accompanying heat can be used fruitfully. In other words the nuclear reactor can be portrayed as a furnace in which heat is produced because of fission chain reaction. The reactor building has a height of 72 m and 46 m diameter And dome shaped structure in the top
Life Explained On the first day. God created the cow. God said “You must go to the field along with the farmer all day long and suffer under the hot sun, give birth to calves and also give milk to farmer. I will give you a life span of 60 years. The cow replied “ That is a tough life which you want me to lead” So please allot me only 20 year life span and take back 40 years. God agreed. On the second day god created the monkey. He said Do monkey tricks, Entertain people, and make them laugh. I will give you a life span of 20 years. The monkey replied “ How boring to perform monkey tricks for 20 years”. So please allot me only 10 year life span and take back 10 years. God agreed. On the third day god created the dog. Sit in all day by the door of your house and bark at anyone who passes by. I will give you a life span of 20 years. The dog replied “ 20 years is too long a period for barking”. So please allot me only 10 year life span and take back 10 years. God agreed. On the fourth day god created man. He said you have to do nothing. Eat sleep and enjoy. I will give you a life span of 20 years The man replied What only 20. I will take the 40 left by the cow and 10 each left by monkey and dog. That makes man’s life span 80. God agreed. So it is in the first twenty years we enjoy life. For the next 40 years we slave in the sun to support our family. For the next 10 years we do monkey tricks to entertain our grandchildren. For the last 10 years we sit in front of the porch and bark at everyone. Life has now been explained.
Toposheet Mark 2 km X 1 km area Draw circles Note down villages and find population We have Google earth software- Helpful in preliminary location GPS instrument gives the latitude/longitude and helpful in site survey (Rs 10000-Rs 80000)
Most other, nuclear plants are designed to withstand earthquakes, and in the event of major earth movement, to shut down safely. A fault is said to be capable if it shows evidence of movement at or near the surface within the past one half million years. Investigations An assessment of seismotectonic analysis by an expert agency. This has to be in combination with geological assessment. Initial stage analysis shall ensure that the site does not suffer any rejection criteria and the plant can be engineered safely meeting the AERB criteria. At later stage, seismic instruments may also be required to be set up to assess tectonic activity for a period of one year. For study of faults in ocean area expert agencies like NIO can be associated.
It may be noted that the land required for reactor and auxillaries (6 x 1000 mw ) is only 500 acres as compared to 1170 acres required for locating main plant of 5 x 800 mw coal plant. However in view of exclusion zone requirements in case of Nuclear the overall land requirement is almost same as thermal It may be noted that township is placed outside the 5 km zone
The cooling water system for nuclear power plants will be larger and more expensive than for fossil fuel facilities due to lower efficiencies of the nuclear plant. Typically 1.5 times the requirement in thermal plants Besides in nuclear there is a requirement of ultimate heat sink (*)Typical water requirements in case of an emergency after an accident is in the range of 2000 to 7000 m3/hr For an inland site this water is sourced from a nearby water body called Ultimate heat sink which needs to provide cooling water for 30 days after the accident.
Steam flow(T/hr) PWR-1000 MW 1910 BWR-1000 MW 7500 PHWR-220 MW 1172 PHWR-540 MW 2777 In view of large steam flow at saturated conditions the steam turbines are large and bulky and more costly Kudan 1 hp + 3 lp The exhaust steam from the high-pressure turbine is dried and superheated as it flows through the two combined moisture separator reheaters standing on either side of the high-pressure turbine to reduce the final moisture in the low pressure turbine. The heating steam for reheating is taken from the main steam downstream of the turbine emergency stop valves
While projects totaling 4,000 MW have already been commissioned during the first 4 years of the Xth plan period, projects totaling 9470 MW are at various stages of implementation. Another 5080 MW is under development. In addition, India would diversify its generation portfolio with increasing presence in Gas and Hydro projects.
In July 2008, the DAE said that the large energy gap projected for 2050 could be bridged if 40 GWe capacity PWRs plus Uranium to fuel them were imported during 2012-20. This would sideline the 3 stage indigenous thorium based policy. Used fuel from these PWRs would be reprocessed and the Plutonium used to launch a series of FBRs, which would largely eliminate the energy deficit in 2050.
Diversification into other sources of energy.
Negligible Greenhouse Gases effects
Abundant reserves of Thorium in India & modest reserves of natural uranium. Thorium deposits in India can sustain about 300,000 MWe of power generation for 300 years.
Proven and safe technologies but requires stringent Safety and Quality norms
Reasons for India's foray into Nuclear Power J S Arora
Coal: 2 600 000 t coal (2000 trains of 1300 t each)
Oil: 2 000 000 t oil (10 supertankers)
Uranium: 75 t uranium (Two Truck Load)
Thus dependence on coal & oil will reduce drastically .
Operation of a 1000 MW(e) plant will require each year
J S Arora
CDM benefits of Nuclear Power CDM : Clean Development Mechanism J S Arora THERMAL (2000 MW) NUCLEAR (2000 MW) GHG intensity in gm of CO 2 /Kwh 941 60 Total annual emission in tonnes of CO 2 14013372 893520 Emission reduction in comparison to thermal 0 13119852 Total annual benefit in million dollars taking $10/CER 0 131.19 Total annual benefit in crores of Rs (1USD= Rs 50) 0 655.95
Pressurized light water reactor J S Arora Parameter Value Heat Capacity – per SG in 4 loop system 750 MWt Steam Generation 1449 T/h Primary Water Temp - Inlet 322 0 C Primary Water Temp - Outlet 290 0 C Primary water pressure 16 Mpa Steam pressure – Outlet 6.4 Mpa Feed water temp - Inlet 220 +/- 5 0 C Steam Temp - Outlet 280 0 C
Types of modern pressurized water reactors J S Arora Make Type Certification Status 1 Westinghouse (USA) AP–1000 (1100 MWe) Design Certification done in Dec 2005. Being built in China. 2 Areva (France) EPR (1600 -1750 MWe) Being built in France ,Finland and China. Under design certification in US. 3 Gidopress (Russia) VVER 1000 (1000 MWe) Two being built in Kudankulam, India. VVER 1200 (1200 MWe) Replacement for existing plants in Russia. Operation to start in 2013. 4 Korean Reactors System 80+ (1300 MWe) Design derived from Westinghouse. Design Certification obtained in May -97 APR – 1400 (1450 MWe) Design derived from Westinghouse. First unit expected by 2012.
Types of modern boiling water reactors J S Arora Make Type Certification Status 1 GE- Hitachi (USA) ABWR(1350 MWe) Under Operation in Japan since 1996-97. US NRC Design Certification obtained in May 1997 2 GE - USA ESBWR(1560 MWe) At pre-application stage for NRC design certification in the USA 3 Hitachi- Japan ABWR(600-1700 MWe) Design completed in Japan. At pre application stage for certification. 4 Areva- France SWR – 1000 (1200-1290 MWe) Design completed in 1999. Application submitted for US – NRC certification. 5 Westinghouse(USA) BWR 90+ (1500 MWe) Under design development.
Pressurized Heavy Water Reactors (PHWRs) J S Arora
Types of pressurized heavy water reactors J S Arora SN Make Type Certification Status 1 AECL Canada CANDU-6 (750 MWe) Enhanced model Licensing approval 1997 2 CANDU-9 (925 MWe) 3 ACR 700 (700 MWe) Undergoing certification in Canada 4 ACR 1000 (1000-1200 MWe) 5 India PHWR 540 MWe In operation 6 PHWR- 700 MWe Modified version of 540MWe PHWRs. Yet to be built 7 AHWR- 300 MWe Under Design to use Thorium – Uranium oxide and Thorium Plutonium oxide fuel.
High temperature gas cooled reactors J S Arora
Reactor Types in Use Worldwide PWR : Pressurised water reactor BWR : Boiling water reactor PHWR : Pressurised heavy water reactor GCR : Gas cooled reactor FBR : Fast breeder reactor Source : World nuclear association J S Arora
Radiation exposure ) - From Natural sources During medical investigations Authorised dose limit for public from Nuclear power plant is 1mSv/Yr J S Arora Sl Source mSv/yr 1 Cosmic Rays- Sun 0.4 2 Gamma Rays-Earth 0.5 3 Radon (Decay of Uranium) 1.2 4 Internal (sources in body) 0.3 Sl Source mSv/process 1 Chest X-Ray 0.2 2 CAT Scan 100 3 Thyroid Scan 40 4 Cancer Treatment 15000-75000
Radiation Doses Life Threatening Dose is illustrated as height of Eiffel Tower, Dose limit for Occupational Worker as height of man Dose limit for public as thickness of a brick 0.075 Meters J S Arora
(*) includes area covered by1.6 km (Exclusion zone) & land for township located outside the 5 km zone. Source : CEA report
For 5 x 800 MW units
Main plant : 1170 acres
Grand Total : 2770 acres(*)
(*) includes land for township . J S Arora
Comparison of water requirements J S Arora Nuclear(2000 MW) Thermal (2000 MW) Once through system (Sea water) 4,00,000 m 3 /hr 2,40,000 m 3 /hr Fresh water Make up 1000 m 3 /hr 700 m 3 /hr Closed system – CT 30000 m 3 /hr 12000 m 3 /hr
Comparison of layout J S Arora Facilities only in NPP Reactor Wet steam turbines Spent fuel storage Waste management Stack-45 m Auxillary control room Facilities only in TPP Steam generator Mills Fans Coal handling plant Ash handling plant Ash dyke Chimney-275 m
Comparison of Civil works J S Arora Nuclear Thermal Foundation Preferably on rock- may go even up to a depth of 20m ~4 m Use of piling Not preferred Allowed Concrete grade M 60 M 25- M 30 Excavation and concreting (500 MW ) 6,00,000 cu m ~2,00,000 cum