NUCLEAR POWER COPORATION OF INDIA LTD.
Report Vocational Trainee Programme Anil Chejara IIT-Gandhinagar
This report contains details of basic structure of Indian Nuclear Programme, profile of NPCIL, nuclear reactor arrangement arrangement and functioning at RAPP. It has summary of lectures and observations held during vocational training programme in Nuclear Training Center (NTC) at RAPP. 1
ACKNOWLEDGMENT My Report is the result of the encouragement of many people who helped in shaping it and provide direction valuable support. It is with hearty gratitude that I knowledge their contributions to my report. I would like to thank Shri R.K. Sharma (Training Coordinator) for putting faith in me and his kind support. I am very thankful to my project guide Shri R. P. Saini (Senior Training Officer) and Shri M.L. Khichi (Training Officer) for giving their precious guidance as and when needed. I am thankful to Shri K.M. Jain (TO) for providing necessary guidance in selecting reference material and explaining everything. I am very grateful to Shri Ashok Kumawat (SO/E), who has always been a great source of inspiration. I am also thankful to all those engineers and technicians without whom it was not possible for me to clear my doubts and difficulties.
ANIL KUMAR CHEJARA (VOCATIONAL TRAINEE, MAY-JULY,2011)
JR. UNDERGRADUATE DEPT. OF MECHANICAL ENGINEERING IIT-GANDHINAGAR, AHMEDABAD E-MAIL: :
[email protected] :
[email protected]
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CONTENTS Sr. No. 1
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Description Abstract Need for Nuclear Power Electricity Generation in India Indian Nuclear Programme NPCIL Mission NPCIL Plants Operating Performance Safety Performance Biodiversity Conversation Future Plan Financial Positions RAPP (Rajasthan Atomic Power Plant) Nuclear reactor Type of Nuclear Reactors Component of Nuclear Reactor PHWR (Pressurized Heavy Water Reactor) PHWR Arrangement RAPS PHWR Arrangement Waste Management Types of Radioactive Waste Reprocessing Radiation Dose Measurement TLD (Thermo Luminescence dosimeter) NTC Report Bibliography
Page No. 4 4 5 6 7 7 8 9 10 10 10 11 12 12 13 14 15 17 18 19 20 22 22 22 23 37
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ABSTRACT Nuclear energy has turned out to be the achievement of the past century. The most clean environmental friendly and of less running cost mode of power generation generation is now in our hand. At present it is estimated that our natural reserves of U3O8 is about 70,000 tones, but the long run potentials depends upon the large reserves of Thorium which is about 3,60,000 3,60,000 tones. The optimum usage of the available available resources takes place via three thr ee stages namely:a. The first stage and perhaps used widely is using natural uranium as fuel. b. The plutonium thus yield by first stage along with thorium is fed in Fast Breeder Reactors. c. The third stage would employ the U-233 obtained from second stage together with thorium is employed. Perhaps the third stage could either be a fast reactor or a thermal thermal reactor. In fact reactors high energy neutrons are required to bring about fission. It is most common with element having even number of mass number. number. In thermal reactors, thermal neutrons neutrons i.e. slow moving neutrons are required to being about the fission. Those having mass number as as an odd number possess this type of property.
NEED FOR NUCLEAR POWER The exploration of natural resources for generation of electricity has been an evolutionary process. Over the years, it has progressed from tapping the potential energy of falling water to burning of fossil fuels. But the quest for more sources of electricity, which is the cleanest and most efficient form of energy, is unending and the limits of the conventional sources have served to heighten man’s anxious efforts in this regard. The discovery of fission and the promise of abundance which nuclear energy came to hold 4
subsequently turned man’s attention to utilize the potential of this source. Considering the current
population growth which has already crossed 100 crores in the 21st century and improvements in standard of living of the forth coming generations, there will be a large increase in the need of mechanical energy particularly from clean, green and safe energy sources. The mechanical energy will play a vital role in sustainable development of the country. Among all the available conventional and non conventional energy sources, the nuclear energy is most efficient, abundantly available, sustainable and cost effective energy sources. It does not emit obnoxious gases that cause global warming, ozone hole and acid rain.
ELECTRICITY GENERATION IN INDIA About 64.75% of the electricity consumed in India is generated by thermal power plants, 21.73% by hydroelectric power plants, 2.78% by nuclear power plants and 10.73% by Renewable Energy Sources. More than 50% of India's commercial energy demand is met through the country's vast coal reserves. The country has also invested heavily in recent years in renewable energy utilization, especially wind energy. In 2010, India's installed wind generated electric capacity was 13,064 MW. Additionally, India has committed massive amount amount of funds for the construction of various nuclear reactors which would generate at least 30,000 MW. In July 2009, India unveiled a $19 billion plan to produce 20,000 MW of solar power by 2022.
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INDIAN NUCLEAR POWER PROGRAMME India’s Atomic Energy programme has been a mission-oriented comprehensive programme programme with a
long-term focus. From its inception the guiding principle of this programme has been self-reliance through the utilization of domestic mineral resources, and building up capability to face possible restrictions in international technology and the exchange of resources. The events of the last 50 years have, in fact, validated this approach. The Department of Atomic Energy (DAE) in India is today a broad-based multidisciplinary organization incorporating basic and applied research, technology development and their translation into industrial application, as closely linked activities. As a result, India today builds its own thermal reactors and associated nuclear fuel cycle facilities and is well poised to march on to the second and third stages of its planned programme involving fast breeder and thorium utilization technologies respectively. This effort is expected to provide a significant long-term solution to India’s crucial electricity needs to support its overall development. The Department of Atomic Energy (DAE) is a department directly under the Prime Minister of India with headquartered in Mumbai. The department is responsible for nuclear technology, including nuclear power and research. The Headquarters of Indian Nuclear Power Projects are located at Mumbai.
DAE
Regulatory Board and Organization
Public Sector
Research & Development Sector
Universities
Aided Sector & Industries and Mining
Atomic Energy Regulatory Board (AERB), Mumbai, Maharashtra Atomic Energy Commission (AEC) Mumbai, Maharashtra Board of Radiation and Isotope Technology (BRIT), Mumbai, Maharashtra
Nuclear Power Corporation of India (NPCIL), Mumbai, Maharashtra
COMPANY PROFILE
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NUCLEAR POWER CORORATION OF INDIA LTD. (NPCIL) The Nuclear Power Corporation of India Limited (NPCIL) is a government-owned corporation corporation of India based in Mumbai. One of the public sector undertakings, it is wholly owned by the Union Government and is responsible for the generation of nuclear power for electricity. NPCIL is administered by the Department of Atomic Energy (DAE), part of the Ministry of Science and Technology. NPCIL is the only power utility company in India which uses nuclear fuel sources. NPCIL was created in September 1987 as public limited company under the Companies Act 1956, "with the objective of undertaking the design, construction, operation operation and maintenance of the atomic power stations for generation of electricity in pursuance of the schemes and programmes programmes of the Government of India under the provision of the Atomic Energy Act Act 1962." All nuclear power plants operated by the company are certified for ISO-14001 (Environment Management System).
NPCIL is responsible for design, construction, commissioning and operation of nuclear power reactors. Atomic Energy Act, 1962. NPCIL has also equity participation in BHAVINI, an organization formed for implementation for Fast Breeder Reactors programme in the country. NPCIL is the sole body responsible for constructing and operating India's commercial commercial nuclear power plants. As of November 27, 2010 the company had 20 nuclear reactors in operation at six locations, a total installed capacity of 4780 MWe. Subsequent to the government's decision to allow private companies to provide nuclear power, the company has experienced problems with private enterprises "poaching" its employees.
NPCIL’S
MISSION
The Mission of the Company is ‘To develop nuclear power technology and to produce
nuclear power as a safe, environmentally benign and economically viable source of electrical energy to meet the increasing electricity needs of the country'.
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NPCIL Plants: OPERATING NUCLEAR PLANTS 1) Tarapur Atomic Power Station (TAPS) 2) Rajasthan Atomic Power Station (RAPS) 3) Madras Atomic Power Station (MAPS) 4) Narora Atomic Power Station (NAPS) 5) Kakrapar Atomic Power Station (KAPS) 6) Kaiga Generating Station (KGS)
1) Under Operation: UNIT
TAPS-1 (Tarapur,Maharashtra) TAPS-2 TAPS-3 TAPS-4 RAPS-1(Rawatbhata,Rajasthan) RAPS-2 RAPS-3 RAPS-4 RAPS-5 RAPS-6 MAPS-1 (kalpakamm,tamilnadu) MAPS-2 NAPS-1 NAPS-2(Narora,U.P.) KAPS-1 KAPS-2 KGS-1 (kakarpur,Gujarat) KGS-2 KGS-3 KGS-3
TYPE BWR
CAPACITY (MWe) 160
BWR PHWR PHWR PHWR PHWR PHWR PHWR PHWR PHWR PHWR PHWR PHWR PHWR PHWR PHWR PHWR PHWR PHWR PHWR
160 540 540 100 200 220 220 220 220 220 220 220 220 220 220 220 220 220 220 TOTAL-4780
TYPE LWR LWR PHWR PHWR PHWR PHWR
CAPACITY 1000 1000 700 700 700 700 TOATL-4800
SINCE
October 28, 1969 October 28, 1969 August 18, 2006 September 15, 2005 December 16, 1973 April 1, 1981 June 1, 2000 December 23, 2000 February 4, 2010 March 31, 2010 January 27, 1984 March 21, 1986 January 1, 1991 July 1, 1992 May 6, 1993 September 1, 1995 November 6, 2000 May 6, 2000 May 6, 2007 November 27, 2010
2) Under Construction UNIT KNPP-1 KNPP-2 KAPS-3 KAPS-4 RAPS-7 RAPS-8
EXPECTED DATE JUNE-2011 MAR-2011 JUN-2015 DEC-2015 JUN-2016 DEC-2010
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OPERATING PERFORMANCE Highest ever nuclear power generation of 26473 MUs was achieved in the year 2010-11, registering an increase in electricity generation of 41% as compared to the generation in the previous financial year 2009-10. NPCIL continued c ontinued its journey of operating reactors continuously without outages by recording continuous operation of more than a year y ear by Madras Atomic Power Station Unit-2 and Tarapur Atomic Power Station Unit-2 by the year 2010-11. So far eight reactors have registered continuous run of more than a year. NPCIL has consistently maintained overall availability factor of reactors above 80% for several years and in the year 2009-10 it reached up to 92%.
SAFETY PERFORMANCE NPCIL has achieved more than 337 reactor years of safe nuclear power plant operating experience. NPCIL operates plants with motto ‘Safety first and Production next'. The Environmental Management System (EMS) and Occupational Health and Safety Management System (OHSMS) as per ISO-14001: 2004 and IS-18001: 2007 respectively are maintained at all the stations. By following the principle of ALARA (As Low As Reasonably Achievable) and maintaining the highest standards of safety within the Nuclear Power Plants (NPPs), the occupational exposures of employees of the company at various NPPs are maintained well below the values specified by the regulator, re gulator, Atomic Energy Regulatory Board (AERB). The environmental releases of radioactive effluents from NPPs are maintained significantly low (average less than 1% of the limits specified by AERB). NPCIL contributed in enhancing safety & reliability of nuclear power plants globally throu gh its active participants in World Association of Nuclear Operators (WANO), Candu Owners Group (COG), IAEA and other international organizations. NPCIL units have been receiving several safety awards form various national agencies like AERB, NSCI, Gujarat Safety Council, National Safety Council-Mumbai and DGFASLI.
BIODIVERSITY CONSERVATION NPCIL has voluntarily taken up Environment Stewardship Programme (ESP), besides fulfilling regulatory and statutory requirements. The programme focuses on the scientific study of bio-diversity, particularly avifauna, within and around Exclusion Zones (EZs) of Indian nuclear power plants for the conservation & improvement of habitat in association with the Bombay Natural History Society (BNHS). NPCIL has publishe d a coffee table book “Our Flying Guests” on the birds found within and around all the Indian nuclear nu clear power plants.
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FUTURE PLAN The plan proposals have been made in line with the key drivers for nuclear power p ower programme of DAE. New schemes, taking advantage of international co-operation for capacity addition, have also been considered. The XI plan proposal envisages capacity addition of 2660 MW through completion of ongoing projects and proposed start of construction activities on 8 Units of indigenous 700 MW PHWRs and 10 Units of 1000 MW LWRs with import option. Government has given in-principle in- principle approval for five new green field site in the state of Haryana, M.P., A.P., Gujarat and West Bengal. Various pre -project activities at these sites and at Kudankulam and Jaitapur sites are going on in mission mode. The company has recognized the necessity nece ssity of developing indigenous capability to support this growth and has initiated the setting up of facilities to manufacture major components by the leading industry partners. The prospect of opening ope ning up of nuclear trade with India has encouraged several suppliers from around the world to visit NPCIL and have exploratory discussions. Various MoU and JVs have been signed to facilitate the implementation of the nuclear power programme in the country. In the diversification front, action is being taken to enhance the capacity of the Kudankulam Wind Farm capacity. NPCIL has been looking for opportunities for investing in Hydel to support peak demands. An MOU has been signed with Tehri Hydro Electric Development Corporation for setting up of Pump Storage Scheme at two potential sites. Maharashtra government has already given its approval for the proposed sites at Malshej Ghat & Humbarli.
FINACIAL POSITIONS: The authorised share capital of the company is Rs. 15,000 1 5,000 crore, of which Rs. 10,145 10 ,145 crore was paid up as on March 31, 2011 fully subscribed by the Government of India. The total asset was Rs. 41894 Cr. and Reserve R eserve Surplus Rs.13893 Cr. as on March 31, 2011. 20 11. For the financial year 2010-11 the total income was Rs.6897 crore, PAT Rs.1376 crore, the revenue realisation 98.92% and dividend paid was 30% of the net profit. The average tariff was Rs. 2.49 per unit.
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RAJASTHAN ATOMIC POWER STATION (RAPS) INTRODUCTION: The Rajasthan Atomic Power Station (RAPS)( Rajasthan Atomic Power Project - RAPP) in India is located about 65 kilometres from Kota by way of the Chambal River, approximately approximately 3 kilometres above the dam that holds the Rana Pratap Sagar lake. The plant lies in the Federal State Rajasthan, district Chittorgarh. The next locale is Tamlao, Rawatbhata is approx. 11 kilometres far away, which is where the plant is located. In Kota a factory for heavy water water operated in the 80s. RAPS is India's first CANDU type pressurized heavy water reactor (PHWR). The project started in 1968 with Canadian assistance for the 220 MW reactors which became critical on 11 August 1973, starting commercial commercial operation on December 16, 1973. After the Indian nuclear weapon test of 18 May 1974 in Pokharan, Canadian support was withdrawn. Therefore, the second reactor only became critical in October 1981. It went into commercial operation operation on April 1, 1981. In the context of the Indian atomic program, two more PHWR with an output of 220 MW each were built. They cost around 570 million dollars. RAPS-3 became critical on 24 December 1999, RAPS-4 became critical on 3 November 2000. Commercial Commercial operations began on June 1, 2000 for unit 3, and on December 23, 2000 for unit 4. Two more reactors (RAPS-5 and RAPS-6) with 220 MWe have also been built, with unit 5 beginning commercial commercial operation on February 4, 2010, and unit 6 on March 31, 2010.The new 700 MWe series of reactor i.e. (RAPP-7 and RAPP-8) will be under construction soon and (RAPS-9 and RAPS-10) RAPS-10) earlier planned now will not be constructed.
NUCLEAR POWER PLANT: Nuclear power plant many parts and basic parts are mentioned below. 1) NUCLEAR RAECTOR 2) WASTE MANAGEMENT 3) MANTAINANCE 4) POWER SUPPLY SECTION
NUCLEAR REACTOR: A nuclear reactor produces and controls the release of energy from splitting the atoms of certain elements. In a nuclear power reactor, r eactor, the energy released is used as heat to make steam to generate electricity. Nuclear reactor initiates and controls a sustained nuclear chain reaction. The most common use of nuclear reactors is for the generation of electric energy and for the propulsion of ships. Heat from
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nuclear fission is used to raise steam, which runs through turbines, which in turn powers either ship's propellers or electrical generators.
NUCLEAR FISSION REACTION:
When a large fissile atomic nucleus such as uranium-235 or plutonium-239 absorbs a neutron, it may undergo nuclear fission. The heavy nucleus splits into two or more lighter nuclei, releasing kinetic energy, gamma radiation and free neutrons; collectively known as fission products. A portion of these neutrons may later be absorbed by other fissile atoms and trigger further fission events, which release more neutrons, and so on. This is known as a nuclear chain reaction. The reaction can be controlled by using neutron poisons, which absorb excess neutrons, and neutron moderators, which reduce the velocity of fast neutrons, thereby turning them into thermal neutrons, which are more likely to be absorbed by other nuclei. Increasing or decreasing the rate of fission has a corresponding effect on the energy output of the reactor. Commonly used moderators include regular (light) water, solid graphite and heavy water.
Nuclear Chain Reaction
TYPES OF NUCLEAR REACTORS: 1) 2) 3) 4) 5) 6)
Pressurised Water Reactor (PWR) Boiling Water Reactor (BWR) Pressurised Heavy Water Reactor 'CANDU' (PHWR) Gas-cooled Reactor (AGR & Magnox) Light Water Graphite Reactor (RBMK) Fast Neutron Reactor (FBR)
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COMPONENTS OF NUCLEAR REACTORS: There are several components common to most types of reactors: Fuel: Uranium is the basic fuel. Usually pellets of uranium oxide (UO 2) are arranged in tubes to form fuel rods. The rods are arranged into fuel assemblies in the reactor core. Moderator: This is material in the core which slows down the neutrons released from fission so that they cause more fission. It is usually water, but may be heavy water or graphite. Control rods: These are made with neutron-absorbing material such as cadmium, hafnium or boron, and are inserted or withdrawn from the core to control the rate of reaction, or to halt it. In some PWR reactors, special control rods are used to enable the c ore to sustain a low level of power efficiently. (Secondary shutdown systems systems involve adding other neutron absorbers, usually as a fluid, to the system.)
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Coolant: A liquid or gas circulating through the core so as to transfer the heat from it. . In light water reactors the water moderator functions also as primary coolant. Except in BWRs, there is secondary coolant circuit where the steam is made Pressure vessel or pressure tubes. Usually a robust steel vessel containing the reactor core and moderator/coolant, but it may be a series of tubes holding the fuel and conveying the coolant coo lant through the moderator.
c oolant bringing heat from Steam generator: Part of the cooling system where the primary coolant the reactor is used to make make steam for the turbine. turbine. Reactors may have up to to four "loops", each with a steam generator. (not in BWR) Containment: The structure around the reactor core which is designed to protect it from outside intrusion and to protect those outside from the effects of radiation in case of any malfunction inside. It is typically a metre-thick concrete and steel structure.
PRESSURISED HEAVY WATER REACTOR (PHWR): IN this nuclear power reactor, commonly using unenriched natural uranium as its fuel, that uses heavy water (deuterium oxide D 2O) as its coolant and moderator. The heavy water coolant is kept under pressure in order to raise its boiling point, allowing it to be heated to higher temperatures without boiling.
Purpose of using heavy water: To making a working reactor is to slow some of the neutrons to the point where their probability of causing nuclear fission in 235U increases to a level lev el that permits a sustained chain reaction in the uranium as a whole. This requires the use of a neutron moderator, which absorbs some of the neutrons' kinetic energy, slowing them down to energy comparable to the thermal energy of the moderator nuclei themselves. During this slowing14
down process it is beneficial to physically separate the neutrons from the uranium, since U nuclei have an enormous parasitic affinity for neutrons in this intermediate energy range (a reaction known as "resonance" absorption). This is a fundamental reason for designing reactors with discrete solid fuel separated by moderator, rather than employing a more homogeneous mixture of the two materials.
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Water makes an excellent moderator; the hydrogen atoms in the water molecules are very close in mass to a single neutron, and the collisions thus have a very efficient momentum transfer, similar conceptually to the collision of two billiard balls. However, in addition to being a good moderator, water is also fairly effective at absorbing neutrons. Using water as a moderator will absorb enough neutrons that there will be too few left over to react with the small amount of 235U in the fuel, again precluding criticality in natural uranium
One complication of this approach is the requirement to build uranium enrichment facility, which are generally expensive to build and operate. They also present a nuclear proliferation concern; the same systems used to enrich the 235U can also be used to produce much more "pure" weapons-grade material (90% or more 235U), suitable for producing a nuclear bomb. This is not a trivial exercise, e xercise, by any means, but feasible enough that enrichment facilities present a significant nuclear proliferation risk. An alternative solution to the problem is to use a moderator that does not absorb neutrons as readily as water. In this case potentially all of the neutrons being released can be moderated and used in reactions with the 235U, in which case there is enough 235U in natural uranium to sustain criticality. One such moderator is heavy water, or deuterium-oxide. Although it reacts dynamically with the neutrons in a similar fashion to light water (albeit with less energy transfer on average, given that heavy hydrogen, h ydrogen, or deuterium, is about twice the mass of hydrogen), it already has the extra neutron that light water would normally tend to absorb. This abundance of neutrons is also the reason why PHWR's are better to "breed" materials such as plutonium or lithium, which are main ingredients of nuclear weapons.
Advantages and disadvantages: The use of heavy water moderator is the key to the PHWR system, enabling the use of natural uranium as fuel (in the form of ceramic UO 2), which means that it can be operated without expensive uranium enrichment facilities. Additionally, the mechanical arrangement of the PHWR, which places most of the moderator at lower temperatures, is particularly efficient because the resulting thermal neutrons are "more thermal" than in traditional designs, where the moderator normally runs hot. This means that a PHWR is not only able to "burn" natural uranium and other fuels, but tends to do so more efficiently as well. Pressurised heavy water reactors do have some drawbacks. Heavy water generally costs very high, though this is a trade-off against reduced fuel costs. It is also notable that the reduced energy content of natural uranium as compared to enriched uranium necessitates more frequent replacement of fuel; this is normally accomplished by use of an on-power refuelling system. The increased rate of fuel movement through the reactor also results in higher volumes of spent fuel than in reactors employing enriched uranium; however, as the 15
unenriched fuel was less reactive, the heat generated is less, allowing the spent fuel to be stored much more compactly.
PHWR ARRANGEMENT: The PHWR reactor design has been developed d eveloped since the 1950s in Canada as the CANDU, and more recently also in India. India. It uses natural uranium (0.7% U-235) oxide as fuel, hence needs a more efficient moderator, in this case heavy water (D 2O) with the CANDU system, the moderator is enriched (i.e. water) rather than the fuel. The moderator is in a large tank called a calandria, penetrated by several hundred horizontal pressure tubes which form channels for the fuel, cooled by a flow of heavy water under high pressure in the primary cooling circuit, reaching 290°C. As in the PWR, the primary coolant generates steam in a secondary circuit to drive the turbines. The pressure tube design means that the reactor can be refuelled progressively without shutting down, by isolating individual pressure tubes from the cooling circuit.
A CANDU fuel assembly consists of a bundle of 37 half metre long fuel rods plus a support structure, with 12 bundles lying end to end in a fuel channel. Control rods penetrate the calandria vertically, and a secondary shutdown system involves adding gadolinium to the moderator. The heavy water moderator circulating through the body of the calandria vessel also yields some heat. Newer PHWR designs such as the Advanced Candu Reactor (ACR) have light water cooling and slightly-enriched fuel.
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CALANDRIA: Calandria is the reactor core of the CANDU reactor. Fuel and coolant (Calandria) tubes run horizontally. Moderator inlet and outlet tubes direct the moderator through the calandria, then to the external heat exchanger for cooling. The control rods enter from the top and control the distribution of power in the reactor and can be used to shutdown the reactor. The shield tank is used to reduce reduc e radiation levels near the reactor.
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REFULING MACHINE AND CALANDRIA:
CANDU reactors can be refueled on-line. This photo shows the refueling machine. New fuel assemblies are added horizontally and the spent fuel assemblies are pushed out to the spent fuel storage area. The fuel design is shown below.
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CANDU FUEL ASSEMBLY: The fuel assemblies used in the reactor are ~ 1.5 feet (0.5 m) long, consisting of individual rods. The cladding is Zircaloy and the fuel pellets consist of uranium dioxide. These pellets are kept in the zircalloy tubes and are 24 per tube. The tubes are known as pencils and 19 pencils make a complete fuel bundle. The pencils are held between end plates and zircalloy provide spacing between the tubes and zircalloy pads provide bearing action. This help mixing of the coolant flow with the sub channels between the elements.
RAPS ASSEMBALY: CALANDRIA: The specifications of 200 MWe reactors calandria are:Weight:
22 tons
Length:
4645 mm
Main Shield I.D. : 5996 5996 mm Small Shell I.D.: 4928 mm Thickness of Shell: 25 mm
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WASTE MANAGEMENT: Nuclear power is characterised by the very large amount of energy available from a very small amount of fuel. The amount of waste is also relatively small. However, much of the waste is radioactive and therefore must be carefully managed as hazardous waste. Since the radioactive wastes are essentially created in a nuclear power reactor, it is accepted that they are the responsibility of the country which uses uranium to generate power. There is no moral or legal basis for the responsibility to be elsewhere.
RADIOACTIVITY: Radioactivity arises naturally from the decay of particular forms of some elements, called isotopes. There are three kinds of radiation to consider: alpha, beta and gamma. A fourth kind, neutron radiation, generally only occurs inside a nuclear r eactor. Different types of radiation require different forms of protection:
Alpha radiation cannot penetrate the skin and can be blocked out by a sheet of paper, but is dangerous in the lung. Beta radiation can penetrate into the body but can be blocked out by a sheet of aluminium foil. Gamma radiation can go right through the body and requires several centimetres of lead or concrete, or a metre or so of water, to block it.
All of these kinds of radiation are, at low levels, naturally part of our environment. Any or all of them may be present in any classification of waste.
Radioactive wastes comprise a variety of materials requiring different types of management to protect people and the environment. They are normally classified as low-level, mediumlevel or high-level wastes, according to the amount and types of radioactivity in them.
Three general principles are employed in the management of radioactive wastes: 19
Concentrate-and-Contain Dilute-and-Disperse Delay-and-Decay.
The first two are also used in the management of non-radioactive wastes. The waste is either concentrated and then isolated, or it is diluted to acceptable levels and then discharged to the environment. Delay-and-decay however is unique to radioactive waste management; it means that the waste is stored and its radioactivity is allowed to decrease naturally through decay of the radioisotopes in it.
TYPES OF RADIOACTIVE WASTE: LOW LEVAL WASTE:
Low-level Waste is generated from hospitals, laboratories and industry, as well as the nuclear fuel cycle. It comprises paper, rags, tools, clothing, filters etc. which contain small amounts of mostly short-lived radioactivity. It is not dangerous to handle, but must be disposed of more carefully than normal garbage. Usually it is buried in shallow landfill sites. To reduce its volume, it is often compacted or incinerated (in a closed container) before disposal. Worldwide it comprises 90% of the volume but only 1% of the radioactivity of all rad. waste. INTERMEDIATE LEVEL WASTE:
Intermediate-level Waste contains higher amounts of radioactivity and may require special shielding. It typically comprises resins, chemical sludges and reactor components, as well as contaminated materials from reactor decommissioning. Worldwide it makes up 7% of the volume and has 4% of the radioactivity of all rad. waste. It may be solidified in concrete or bitumen for disposal. Generally short-lived waste (mainly from reactors) is buried, but longlived waste (from reprocessing nuclear fuel) is disposed of deep underground.
HIGH LEVEL WASTE:
High-level Waste may be the used fuel itself, or the principal waste separated from reprocessing this. While only 3% of the volume of all rad. waste, it holds 95% of the radioactivity. It contains the highly-radioactive fission products and some heavy elements with long-lived radioactivity. It generates a considerable amount of heat and requires cooling, as well as special shielding during handling and transport. If the used fuel is reprocessed, the separated waste is vitrified by incorporating it into borosilicate (Pyrex) glass which is sealed inside stainless steel canisters for eventual disposal deep underground. On the other hand, if used u sed reactor fuel is not reprocessed, all the highly-radioactive isotopes remain in it, and so the whole fuel assemblies are treated as high-level waste. This used fuel takes up about nine times the volume of equivalent eq uivalent vitrified high-level waste which is separated in reprocessing. Used fuel treated as waste must be encapsulated encapsulated ready for disposal. Both high-level waste and used fuel are very radioactive and people handling them 20
must be shielded from their radiation. Such materials are shipped in special containers which prevent the radiation leaking out and which will not rupture in an accident. Whether used fuel is reprocessed or not, the volume of high-level waste is modest, - about 3 cubic metres per year of vitrified waste, or 25-30 tonnes of used fuel for a typical large nuclear reactor. The relatively small amount involved allows it to t o be effectively and economically isolated. Wastes from the nuclear fuel cycle radioactive wastes occur at all stages of the nuclear fuel cycle - the process proce ss of producing electricity from nuclear materials. The fuel cycle comprises the mining and milling of the uranium ore, its processing and fabrication into nuclear fuel, its use in the reactor, the treatment of the used fuel taken from the reactor after use and finally, disposal of the wastes. The fuel cycle is often considered as two parts - the "front end" which stretches from mining through to the use of uranium in the reactor - and the "back end" which covers the removal of used fuel from the reactor and its subsequent treatment and disposal. This is where radioactive wastes are a major issue. Wastes from the "back end" of the fuel cycle: It is when uranium is used in the reactor that significant quantities of highly radioactive wastes are created. When the uranium-235 atom is split it forms fission products, which are very radioactive and make up the main portion of nuclear wastes retained in the fuel rods. There is also a relatively small amount of radioactivity induced in the reactor components by neutron irradiation.
About 27 tonnes of used fuel is taken each year from the core of a l000 MWe nuclear reactor. This fuel can be regarded entirely as waste (as, for 40% of the world's output, in USA and Canada), or it can be reprocessed (as in Europe and Japan). Whichever option is chosen, the used fuel is first stored for several years under water in cooling ponds at the reactor site. The concrete ponds and the water covering the fuel assemblies provide radiation protection, while removing the heat generated during radioactive decay.
STROAGE TANK 21
REPROCESSING: The used fuel is later reprocessed, it is dissolved and separated chemically into uranium, plutonium and high-level waste solutions. About 97% of the used fuel can be recycled leaving only 3% as high-level waste. The recyclable portion is mostly uranium depleted to less than 1% U-235, with some plutonium, p lutonium, which is most valuable. Arising from a year's operation of a typical l000 MWe nuclear reactor, about 230 kilograms of plutonium (1% of the spent fuel) is separated in reprocessing. This can be used in fresh mixed oxide (MOX) fuel (but not weapons, due its composition). MOX fuel fabrication occurs in Europe, with some 25 years of operating experience. The main plant is in France, and started up in 1995. Japan's slightly smaller plant is due to start up in 2012. Across Europe, over 35 reactors are licensed to load 20-50% of their cores with MOX fuel. The separated high-level wastes - about 3% of o f the typical reactor's used fuel - amounts to 700 kg per year and it needs to be isolated from the environment for a very long time. Major commercial reprocessing plants are operating in France and UK, with capacity o f almost 5000 tonnes of used fuel per year, - equivalent to at least one third of the world's annual output. A total of some 90,000 tonnes of spent fuel has been reprocessed at these over 40 years.
RADITION DOSE MEASURING: Thermo Luminescence dosimeter (TLD): TLD measures ionizing radiation exposure by measuring the amount of visible light emitted from a crystal in the detector when the crystal is heated. The amount of light emitted is dependent upon the radiation exposure. This is a badge type device and it consists of a TLD CARD loaded in a CASSETTE. TLD cassette has a dual metallic filter and an open window to distinguish between doses received due to different type of radiation (alpha, beta & gamma) and provides energy dependence correction.
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NTC REPORT MECHANICAL FUNDAMENTAL EQUIPMENTS: Vocational trainees entering in the field of Operation and Maintenance are required to gain a fundamental knowledge about the mechanical components and equipments being used. Mechanical Fundamental Equipments is needed to impart initial knowledge about the purpose, types, basic construction details, application and importance of mechanical components and equipments. Theses fundamental equipments are described.
BEARINGS: Bearing is an important component of any mechanical equipment. The function of bearing is to take forces acting on them and direct motion of shaft in axial as well as radial direction depending on the requirement. The motion may invo lve either sliding or rolling friction between the corresponding members or elements. The principal function of Bearings is to: 1) Support the Load 2) Guide and Locate the Moving Parts 3) Minimise Friction
Plain Bearings or Sliding contact bearings: 23
Plain bearing’s primary motion is sliding. They handle radial and thrust loads, as well as linear motion. Plain bearings may be run dry without a lubricant in some instances where the load is low and motion is slow or intermittent. Rolling Element Bearings: These bearings use some type of rolling element between the loaded members. Relative motion is accompanied and accommodated by rotation of the elements. Bearing races, which conform, to the element shapes are normally used to house them. A cage or separator is often used to locate the elements within the bearing. be aring. Causes of Bearing Failure : • Improper mounting. • Loose or excessive tight fit on the shaft. • Misalignment • Electrical damage • Vibrational brinelling • Inadequate lubrication
SEALS The prevention of leaks is one of the major and one of the most important problems industry is facing. Proper seal designs and proper installation installation of seals are critical for all systems, weather sealing electronic equipment against dirt and moisture, or to prevent a leak in high-pressure fluid system. As per requirement of system sealing, size and type of seal changes. Seals are used for sealing purpose. Sealing is required to maintain pressure, to prevent fluid loss and to keep out the contamination. co ntamination. There are various methods of sealing the components. Depending upon the requirements and conditions various types of seals are used. Seals are classified into two category 1. Static seal. 2. Dynamic seal. Static Seal: A seal that is compressed between two rigidly connected parts is classified as a static seal. The seal itself may move to some distance as pressure is alternately applied and released, but mating parts do not move relative to each other. other . Examples of static seals are mounting gaskets, pipe thread connection, flange joint seals & O rings etc. etc . Dynamic Seal : Dynamic seals are installed between parts which do move relative re lative to one another. Hence atleast one of the parts must rub against the seal and therefore dynamic seals are subject to wear. This naturally makes their design and application more difficult. Some examples of dynamic seals are piston rings, gland packing etc.
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GASKETS:
A gasket is a packing designed to go between two rigid parts of a container c ontainer in an essentially stationary relationship. It is a static seal. Gasketing is material in sheet, striper bulk from which gaskets are prepared. Gaskets are positioned between the joint faces of the flanges and then they are tightened enough so that gasket exerts exe rts more pressure against the faces then the fluid pressure tending to leak past it. There are three principal forces in a joint that affect the funtioning of a gasket Compressive Load : Compressive load is the force that initially compresses the gasket. It is usually applied b y bolting. It must be sufficient to squeeze gasket into all voids in the faces of the flanges that is, the gasket must flow into all ridges and grooves and into all the sruface imperfections and maketight seal so that no path should be there for leaks le aks tight seal that will have no paths for leaks. Hydrostatic End Force : When internal pressure is applied to assembly, the hydrostatic endforce tends to force the flanges apart, and thus reduce the load on the gasket. The T he difference between the initially applied force and the hydrostatic end-force is the residual load on the gasket. Internal Pressure : Pressure of the joint tends to bypass or blow out the gasket material. The strength of the gasket material and the residual load on the gasket must be sufficient to contain this pressure. The ratio of residual load on the gasket area to the internal pressure is referred to as the “m” factor, which is a safety factor. For example, a minimum “m” factor of three is advised for spiral-wound gaskets.
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Depending upon operating conditions and gasket characteristics, gaskets are classified as given below : 1) Non-metallic gasket. 2) Metallic gasket To determine whether metallic or non-metallic gasket should be used, multiply the operating temperature in °F(°C) to operating pressure in psi (Kg/cm 2). If the result exceeds 250000 psi (17500 Kg/cm 2), only metallic gaskets should be used. Generally Gen erally non-metallic gaskets should not be considered above 850 °F (455 °C) or below –65°F ( – –54°C) or for pressures in excess of 1200 psi (84 Kg/cm 2) without consulting a non-metallic gasket supplier. Metallic Gaskets : Following are the types of more popular metallic gaskets : 1) Corrugated or embossed, thin metal. 2) Metal-jacketed, soft filler. 3) Spiral wound. 4) Pure metal gaskets Moulded Packing : Moulded packings are often called automatic, hydraulic or mechanical packings. The fluid f luid being sealed supplies pressure to seal the packings against the wearing surface The general classification of moulded packing can be subdivided into two categories : 1. Lip type 2. Squeeze type OIL SEALS Oil seals are used to seal rotating, reciprocating and oscillating shafts. Normally these seals are used to seal lubricant of bearings and as oil is one of the most popular and useful lubricant in bearings that is why these seals are known as oil seals. Oil seals are classified in two types: 1. Radial lip seal. 2. Felt seal. CIRCUMFERENTIAL CIRCUMFERENTIAL SEAL Circumferential seals are high-performance, low leakage, contact-type seals used for rotary and reciprocating applications. It undergoes high velocity rubbing at their primary sealing surfaces, the seal offers a high order of sealing ability and accommodate unlimited relative axial motion between stationary and moving members. They require smaller space than face seals and are light weight. Following are the types of circumferential seals. 1. Single ring split seal. 2. Multi-ring split seal. 3. Segmented seal. CLEARANCE SEAL : Clearance seals are dynamic seals which limit leakage by closely controlling the annular 26
clearance between rotating or reciprocating shaft and its relatively stationary housing. Two types of clearance seals are normally uysed, these are as below : 1. Labyrinth type. 2. Bushing type. MECHANICAL SEAL The mechanical seal or face seal is the one in which there are two mating mechanical parts which are used to prevent the flow of any fluid out through an opening of a container c ontainer through which any machine part is protuding out both in its static and dynamic condition. That is to seal rotating shafts against the leakage of process fluids. Out of the two mating mechanical parts one is stationary and other will be rotating with
Classification Classification of Mechanical Seal:
POWER TRANSMISSION: The purpose of power transmission components in mechanical equipment is to transmit mechanical power (in form of torque) from the driver to the driven equipment. The driver is normally an electric motor, and the driven may be a pump, compressor, fan, blower etc. Following components are mainly used for power transmission: 1. Shafts 2. Couplings 3. ‘V’ Belts
SHAFTS : The function of the shaft is to transmit the torque or power while rotating and to support the revolving parts. Shafts generally have polished surfaces and are cylindrical in shape. Shafts are made of steel of varying grades intended for specific purpose. They can be 27
classified as Rigid and Flexible.
V-BELTS V Belts are used to transmit power from a drive shaft to a driven shaft where the two shafts are not in the same plane. As the entire power to be transmitted from the driver to the driven passes through the belt, the installation and maintenance of these units assume great importance. V-Belts are available in a wide variety of standardized sizes and types, for transmitting almost any amount of Horse-power. Horse-po wer.
COUPLINGS Couplings are used to join length of shafting or to provide a means of transmitting power from a driving source (e.g. motor) to a driven machine. They may have other function such as:
(a) To take up misalignment of the shaft. (b) To allow for expansion of the shaft caused by heating. (c) To prevent or reduce vibration in shaft system. (d) To allow machinery or section of shafting to be removed for maintenance. Classification Classification of couplings : Couplings can be divided in two types: 1. Rigid couplings 2. Flexible couplings • Rigid couplings provide a fixed union between two shafts. Consequently, the shafts must
have good initial arrangement and stable support bearings. • Flexible couplings are employed to accommodate a small amount of misalig nment
between the driving and driven shafts.
PUMPS: The hydraulic machines, which convert the mechanical mec hanical energy into hydraulic energy, are called pumps. The hydraulic energy is in the form of pressure energy. Most process in industries involves the transportation of liquids, or their transfer from one level of pressure or static energy to another .The pump is the mechanical means for achieving this transport or transfer, and thus becomes an essential part of all processes. Classification Classification Of Pumps Pumps may be classified on the basis of application they serve, the material from which they are constructed, the liquid they handle, and even their orientation in the space. All such classification, however, are limited in scope and tend to substantially overlap each other. A basic system of classification is by which energy e nergy is added to the fluid.
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CENTRIFUGAL PUMPS: The mechanical energy is converted in to pressure energy by means of centrifugal force acting on the fluid, the hydraulic machine is called c alled centrifugal pump. Working Principal The centrifugal pump works on the principle of forced vortex flow. Which means that when a certain mass of liquid is rotated by an external torque, the rise in pressure head of the rotating liquid takes place. It consists of a rotating element including impeller & a shaft and a stationary element made up of a casing, stuffing box. Vanes of impeller impart energy to the fluid through centrifugal force. The fluid is forced into impeller due to differential pressure between pressure at water surface in suction tank and the pressure at suction eye of impeller. Fluid is discharged through impeller outlet at higher pressure & velocity . The velocity is converted into pressure by means of volute or set of stationary diffuser vanes surrounding impeller.
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Working of Centrifugal Pump ROTARY PUMPS Rotary pumps of a number of different types are popular in a variety of services in plant. Usually rotary pumps consist of a fixed casing containing gears, vanes, pistons, screws, or similar elements operating with minimum clearance. Instead of throwing a liquid as in a centrifugal pump, the rotary pump traps it, pushing it around the closed casing, much like a reciprocating pump. Common types of rotary pumps used today include external-gear, internal-gear, lobe, screw, sliding-vane.
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Internal Gear Pump
Eeternal Gear Pump
RECIPROCATING PUMPS Reciprocating pumps converts mechanical energy into hydraulic energy (or pressure energy) by reciprocating action. It sucks the liquid into a cylinder in which a piston is reciprocating re ciprocating (moving backwards and forwards) , which exerts the thrust on the liquid and increases its hydraulic energy (pressure energy), the pump is known as reciprocating pump. Working of a reciprocating pump A single acting -reciprocating pump consists of a piston, which moves forwards and backward in a close fitting cylinder. The movement of the piston is obtained by connecting the piston rod to crank by means of a connecting rod. The crank is rotated by means of an electric motor. Suction and delivery pipes with suction valve and delivery valve are one way valves or non-return valves, which allow the water to flow in one direction only. Suction valve allows water from suction pipe to the t he cylinder while delivery valve allows water from cylinder to delivery pipe only.
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Working of Reciprocating Pump
VALVES: Valves are extensively used in piping system and on equipments to which piping is connected. They enable fluid flow to be handled in a number of different ways. In a nuclear power station valve particularly become important because of a number of valves are used in the primary heat transport system, moderator system and other heavy water lines. This is from the nuclear consideration point of view and also to prevent the loss of heavy water due to leakage from the various valve joints. Valves used in the steam and feed water lines become critical due to high pressure and temperature condition. Valve Functions, Classification & Types:
1) START OR STOP THE FLOW: The starting or stopping the flow is the most widely performed function of valves. The basic requirement in the design de sign of these Valves is that they offer minimum resistance to flow and pressure loss when open.
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GATE, PLUG, BALL & BUTTERFLY Valves are most commonly used for this purpose. Diaphragm valves are preferred in corrosive applications or where tight shut off may be required in low pressure and temperature services.
2) REGULATION OF FLOW: Many applications require that the flow of fluid or gas be regulated or throttled in various steps between closed and open limits. This is generally done by introducing resistance to flow either by a change in direction or by causing a restriction or by combination of both. GLOBE, ANGLE, NEEDLE & BUTTERFLY Valves are most commonly used for this purpose. Close control over flow is most readily obtained with globe or angle type with characterized plug or with needle valves.
3) BACK FLOW RESERVATION: In some application, it is essential to prevent back flow. For this purpose , check valves are generally used. These valves are kept open by fluid flow. They close either by gravity or by the reversal of flow. The T he major types in use are generally designated as lift check and swing check. 4). PRESSURE REGULATION: In some application, the incoming or line pressure must be reduced. The required service pressure will then have to be achieved and maintained uniformly, even when slight variation occur in the line pressure. Valves used for this purpose are referred to as pressure reducing valves or regulators. 5) PRESSURE RELIEF: Relief valves are used in application where excessive ex cessive pressure in the system can cause damage or failure. Some failure have been extremely disastrous. The safety or pop valves generally are spring loaded. They open when the pressure exceeds the limit set for the valve.
CLASSIFICATION OF VALVE ON THE BASIS OF FUNCTION PERFORM: 1. Isolating valves: This type of valve are either fully opened or fully closed. Gate valve, plug Valve and ball valve are examples of this type. 2. Regulating valve: These types of valves regulate or control the rate of flow of fluid according to the requirements. They can be opened in any position from fully opened to fully close. Globe valve, angle valve are examples of this type.
3. Non return/check valve: These types of valves permits the flow of fluid in one direction only and automatically shuts off if a reversal flow occurs. The direction of fluid flow is indicated by an arrow on valve body. Swing check non-return valve and lift check non-return valve v alve are examples of this type.
4) Safety valve: These type of valve are designed to open as soon as the predetermined and set
pressure has been reached on the system. Spring load safety valve and torsion bar type safety valve are examples of this type. 33
HEAT EXCHANGERS: The applications of heat exchangers in power plant, a process industry or a chemical plant is quite at large. They are considered to be one of the most important equipment of the plant from the availability point of view. The overall efficiency of the plant depends largely upon the efficiency of the heat exchangers. They are used in many forms, such as, steam generator, pre-heaters, evaporators, coolers and condensers. There are two main considerations in the selection for a particular type, one is to obtain maximum heat transfer rate per unit surface and the other is low in cost. Heat exchangers in a nuclear power plant p lant are more critically designed and fabricated, considering probable leakage through the various joints, service life, effect due to radiation and inspection and maintenance requirements. It is therefore a must for all the technicians, supervisors and engineers to have a thorough knowledge of the performance p erformance evaluation, operation, inspection and maintenances of the heat exchanger of in or der to keep them in healthy condition at all times. MODES OF HEAT TRANSFER T RANSFER There are three modes of heat transfer.
1) CONDUCTION 2) CONVECTION 3) RADIATION
CONDUCTION In conduction the heat is transfered from one point to the other by actual heat transfer between adjacent atoms or molecules of a solid object. If one end of a iron rod is heated, the other end will also become hot after some time. This is due to conduction. CONVECTION In convection the heat is transferred in a liquid by its molecules in motion. moti on. If some water is taken in a container and heated, eddies are formed in it. It is due to this phenomenon that the heat is transferred in liquids. Infact when water in the lower portion of the container receives heat its density reduces as compared to th e water in the upper portion of the container . This causes the eddies to be formed and heat is transferred from lower portion of the container to the upper portion of it. Like this , gradually whole of the water is heated. This process is called NATURAL CONVECTION. CO NVECTION. If the motion set due to the difference in densities is insufficient for transferring the heat, a FORCED CONVECTION can also be adopted. In case of forced convection, liquid is circulated through the heat exchanger with the help of a pump. RADIATION We already know that the heat is transferred in solids due to conduction of heat from one atom to another atom due to atomic vibration and electrons in motion. In case of liquids heat is transferred due to convection, that is ,by the molecules in motion. The transfer of heat due to radiation is more of a mystery, that is , heat is transferred from one hot object to the other without any transmitting medium in between. 34
Though there are many theories which explains the transfers of heat he at due to radiation but the most popular one is wave theory. According to this theory heat is propagated from one hot object to the other in form of electromagnetic waves, which when fall on another object is reconverted into heat . Our earth receives heat from the sun by radiation ra diation only. PRINCIPLE OF HEAT EXCHANGERS In case of heat exchangers, conduction and convection conv ection are the two ways which are of more concern. For a heat exchanger exc hanger to work efficiently it is necessary for the hot fluid on one side of the separating wall to come in contact with it and raise its temperature. Similarly it is necessary for the cold liquid to come c ome in contact with the hot wall on other side and receive heat. Thus heat is transferred from hot fluid to the cold co ld fluid through the separating wall. For each particle of both, the hot and the cold fluids to come into intimate contact with the wall, it is desirable that there is a high degree de gree of turbulence in both fluids adjacent to the wall. The turbulence increases with the increase in velocity of flow past pa st the wall. If the turbulence adjacent to the wall is not very large, than a portion of the fluid after receiving heat will not move from the wall but remain adhered to it. This reduces the heat transfer. Under this condition we are dependent upon the conductivity co nductivity of not only the wall material but of the film of fluid also. This condition becomes more troublesome if the velocity of flow relative to the wall is very slow. CLASSIFICATIONS OF HEAT EXCHANGERS: EXCHANGERS: 1. Shell and tube type. 2. Spiral Type 3 Finned tube type. 4. Plate type. 5. Double pipe type.
AIR COMPRESSORS: COMPRESSORS: Air is mechanical mixture of gases, mainly Oxygen and Nitrogen. Atmospheric air always contains some amount of water vapour. In air mixture individual molecules of Oxygen and Nitrogen, have wide seperation compared to their size. Molecules are always travelling at high speed at normal temperature, they strike against enclosing surface and produce what we know as Pressure. Energy stored in air in the form of pressure is utilized to do work in various equipments/ instruments in industries. The compressed air serves following purpose in a Nuclear power station; Mask air : Used for supplying breathing air to personnel working in areas containing 1) radioactive or harmful gases. 2) Instrument air : Used for operating pneumatic instruments like actuators, E/E/A converters etc. c hisel etc. and for Service air : Used for operating Pneumatic tools like wrenches, chisel 3) general cleaning purpose.
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CLASSIFICATION The equipment used for compressing the atmospheric air and producing high pressure air is known as a compressor. Various types of Compressors are employed to generate high pressure air.
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BIBLIOGRAPHY: WEB LINKS: www.npcil.nic.in www.world-nuclear.org www.wikipedia.com www.dae.gov.in www.howstuffworks.com www.osun.org www.nptel.iitm.ac.in REFERENCE MATERIAL: Training manual on mechanical equipment eq uipment fundamentals, NTC Library Reactor Physics, NTC Library PHWR Arrangement, NTC Library Waste Management, NTC Library
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