From Volga to Ganga : the Story of Kudankulam

From Volga to Ganga : The Story of Kudankulam

Nu-Power golden beach Kovalam. The temple is a fine example of blend of the Kerala and Dravidian styles of architecture. The internationally renowned Kovalam beach resort, with its three adjacent crescent beaches, is a favorite tourist haunt.

The National Highway No.47 (NH-47) connects Trivandrum and Kanyakumari, my sojourn en-route Kudankulam. The continuous habitats photo: A.I. Siddiqui The Padmanabhaswamy temple in along the high-way makes it difficult for Trivandrum the first time visitors to identify where India’s biggest nuclear power station one city ends and the next town begins. in being set-up at Kudankulam in But farther from Trivandrum, the rows collaboration with the Russian of houses gradually disappear Federation A.I. Siddiqui presents providing overwhelming views of paddy details in this travelogue-cum- fields, coconut grooves and banana technical feature plants all of which are closely integrated with the lives and culture of the people living in this region.

The aerial view of Kanyakumari, named after Goddess Thiruvananthapuram, Trivandrum for Kanyakumari Amman, is about 80 kms short, is mesmerizing – presenting from Trivandrum. Kanyakumari, a small hues of green and blue. As the habitat in Tamil Nadu State, is a very aeroplane de- popular name among scends further, the Indians, as a pilgrim and verdant Kerala re- famous tourist spot. It veals its enthral- has the distinction of ling landscape. being the southern most The Trivandrum point of the mainland airport is comfort- India. Here, Bay of ably devoid of Bengal on one hand and clamours of hotel Arabian Sea on the other agents and taxi- meet the Indian Ocean, men. Trivandrum, presenting captivating the capital city of shades of mixing waters. The dusk and the twin rocks at the southern State Nevertheless, the world Kanyakumari - on the left is Swami Kerala is also fa- famous Vivekananda Vivekananda Rock Memorial and on mous for its Pick. author Rock temple stands tall

the right statue of Thiruvalluvar Padmanabhaswamy photo: A.I. Siddiqui in the sea. The twin rocks photo: A.I. Siddiqui temple and the An artisan at Kanyakumari beach stand amid the sea embossing the sea-shells

* The title of the artical is inspired by the book, ‘From Volga to Ganga’ by Rahul Sankrityayan. His Excellency, the Vice President of India and Chairman of Rajya Sabha, about the book said, “… many years ago, an Indian writer, Rahul Sankrityayan wrote a travelogue titled “From Volga to Ganga”. Even the celebrated author himself didn’t know then, that he was providing the most perfect imagery for the Indo-Russian civilisational encounter. The great rivers represent two great civilisations, and their perennial flow symbolises the permanence, the serum and the continuity of our contacts”. The Vice President was addressing the meeting of Members of Parliament, addressed by His Excellency Mr. Vladimir V. Putin, President of Russian Federation, on October 4, 2000.

An International Journal of Nuclear Power - Vol. 16 No. 1-2 (2002) 35 separated by about 220 feet. The Nagercoil is named after the presiding severe salinity and alkalinity. All these famous philosopher, Swami deity Nagaraja. The Nagaraja temple factors have led to frequent crop Vivekananda meditated here on the is about 20 kms from the city. The pillars failures and very low agriculture night of December 25, 1892, a year of this temple, I am told, are adorned productivity. These adverse agriculture before his attending the Parliament of by the carvings of Jain Tirthankars, conditions have forced the local Religions in Chicago. The superb rock Mahavira and Parshivanath. population to adopt ‘beedi’ (Indian memorial has been erected to cigarette) making and fishing that yields commemorate his visit to the rock. On National Highway No.7 (NH-7) low monetary returns. Kudankulam is one of the rocks, stands 133 feet high connects Kanyakumari and Tirunelveli in Radhapuram Taluka in district statue of Thiruvalluvar, one of the most via Nagarcoil. The first leg of the Tirunelveli of Tamil Nadu State. The respected poets of Tamil, famous for journey from Kanyakumari towards Tirunelveli city is about 75 Kms in north- his work ‘Thirukural’. The height (133- Kudankulam on NH-7 presents, on east direction from Kudankulam. ft) of the sulfur-resistant statue is said both the sides of the road, serried to correspond to the 133 chapters of banana and coconut trees sandwiched The Kudankulam site was chosen by his work. Not far from the Rock between high hillocks and dancing the Site Selection Committee (SSC) of Memorial is a lighthouse, the Kumari paddy fields. Clouds floating across the the Department of Atomic Energy Amman temple and the Gandhi azure sky, Oh! What a land – picture (DAE) way back in 1987-88. The SSC Memorial where the urn containing the perfect with its surrealistic beauty and considered several aspects including ashes of Mahatma was kept before eternal mystique. the guidelines set by the International immersion. It has been designed such Atomic Energy Agency (IAEA). It was that the Sun’s rays fall on the same spot The journey on NH-7 ends at one among the many sites considered every 2nd October – his birthday. In fact, Kavalkinaru and we divert to a country by the SSC. Several factors related to the region has a unique landscape road to reach Kudankulam. A huge nuclear safety as also social, dotted with beautiful temples, churches wind-mill park at Kavalkinaru presents economical and environmental were and mosques distilling unity in diversity. a spectacular sight. As we approach considered by the Committee. Kudankulam, a dramatic change in the The views of sunrise and sunset from landscape can be noticed. Soon after The site is located in low seismic area, Cape Comorin or Kanyakumari are crossing the Anjugramam village, the zone-II as per the Indian Standards of memorable. It is said that it is the only vegetation becomes thorny and bushy. Classification. The classification place in India where sun-set and Coconut and banana trees almost divides the whole country in five Zones, moonrise can be seen simultaneously disappear. The soil appears barren. with zone-I having the lowest and zone on a full moon day. Going little further, the cactus bloom V the highest seismicity. The site does and ant-hills become abundant. not have any active faults in its vicinity. Nuclear Power Corporation of India Kudankulam region is in the rain The site also provides preferable Limited (NPCIL) had, until recently, its shadow area, which means very scanty foundation conditions to build the project office in Nagercoil – the district rains even during thick of rainy season. nuclear power plant upon. The site is headquarters of Kanyakumari district. This semi-arid zone has moderate to free form severe cyclonic activities all photos by: A.I. Siddiqui Road to Kudankulam: Scenes of paddy fields and coconut grooves gradually dissolve into cactus bloom and barren land as we drive towards Kudankulam site

36 Nu-Power though it lies along the coast of Gulf of imported nuclear power plant (NPP) equipment, components and materials Manar, which also provides ample when the country has its own being supplied by the Russian water for the condenser cooling. indigenous programme? Dr. V.K. Federation. Chaturuvedi, CMD, NPCIL clarifies, Mr. S.K. Jain, Director, Light Water “the two light water reactors we are The Russian Federation is funding Reactors and Kudankulam (LWR&KK), importing from the Russian Federation, almost half the project cost. The soft elaborating site specific features points and the other LWRs that we may import loan is at an interest rate of 4% per out that there were no nearby chemical in future are add-ons and will help to annum. Mr. Jain briefs the arithmetic, plants, large industries and military increase the installed nuclear capacity “the loan is to be repaid in fourteen installations as also air corridors. “That rapidly. The project will help to build a equal yearly instalments (EYIs) starting means”, says Mr. Jain, “the possibilities larger operating base, which means a year after the commencement of of explosion, fire, release of better profitability and more internal commercial operation of the plant”. inflammable, explosive, corrosive or surpluses, which will go in a long way How much does it mean? “Assuming a toxic clouds is nil and the chances of to pursue the indigenous programme nominal plant load factor of 68.5%, the loss of flight control does not exist”. more vigorously. In view of huge two units will generate electricity worth demand for power the country’s nuclear Rs. 33991 million per annum compared Kudankulam site is, nevertheless, well power programme which is poised to to the EYI of Rs. 6530 million”, explains connected by road, railways and sea. expand rapidly will become self Mr. Jain. A financially more relevant NH-7 and broad-gauge rail head at sustaining financially too”. indicator is the Debt Service Coverage Kanyakumari and the Tuticorin sea port Ratio (DSCR) which tells whether a about 100 kms, will be used by the Kudankulam project is a Rs.140 billion borrower has earned sufficient revenue project authorities to transport large mega project - the biggest ever to meet the principal and interest equipment and components to the site, undertaken by NPCIL. Explaining on commitments on the outstanding debt informs Project Director (Kudankulam), the cost of project, Dr. Chaturvedi says, after meeting the operating costs. It is Mr. S.K. Agarwal. The Kudankulam site “this is the cost of the completion of the the utility’s cash flow divided by the sum itself has been declared, recently, as a project in the year 2005-2006, including of all its debt payments. For instance, minor port. the interest during construction. It is a if DSCR is more than 1, say 1.2, it firm cost, even the sensitivity of dollar- means to lender that for every rupee The site has a potential for setting up rupee parity fluctuations have been of loan debt that the borrower has to to 6000 MWe installed capacity. The considered in the unit energy cost”. The service, he/she will have Re. 1.2 with first two units of 1000 Russian which to make the payment. The MWe each are presently components average DSCR for Kudankulam project being set-up in technical of funding is is calculated to be about 1.4. “That collaboration of the mainly to shows the economic viability of the Russian Federation. But a cover the cost project” concludes Mr. Jain. pertinent question is, why of services did India need an and supply of The total project cost is the result of a

An International Journal of Nuclear Power - Vol. 16 No. 1-2 (2002) 37 series of negotiations Indian side had capacity as also investment, with their Russian counterparts. commenced with the placement of first “Negotiations have certainly optimised pour of concrete on March 30, 2002 the project cost by an appropriate (See Indian News, this issue). The two sharing of the responsibilities by the units being set-up at Kudankulam with Indian and the Russian sides. This a gross capacity of 1000 MWe each resulted not only in the reduction of belong to Pressurised Water Reactor project cost but it will also provide an (PWR) family, the dominant type of opportunity to the Indian industry to upper block reactor world-wide. This type of water participate in this mega-project” control and cooled water moderated reactor, called says Dr. Chaturvedi. safety system VVER in Russian nomenclature uses the heat guard of the reactor slightly enriched uranium. The fuel for The change in scope of work is the Kudankulam plant is to be supplied explained by Mr. S.K. Agarwal, “Initially, by the Russian Federation. On the fuel reactor cap Indian scope was limited to only arrangements, Dr. Chaturvedi explains, construction of all plant buildings and “our strategy is that who so ever erection of equipment except the main pin chanel for samples supplies the plant enters into a long- steam supply system and the turbo- gasket term contract for supplying fuel for the vessel generator (TG) plant but now it includes set of safety tubes designed life of the plant. We are pit the construction, erection and ensuring that we always have commissioning of the entire plant under adequate fuel for the operation of plant the technical supervision of the Russian for a five-year duration so that we have experts”. Mr. Agarwal informs that the sufficient time to locate alternative Atomic Energy Regulatory Board sources in case of interruption in the (AERB) of India granted construction hurdle supply due to any reason”. consent in March - end 2002. However, fuel assemblies parallel action was initiated by KK control rods Today, the Kudankulam site is buzzing project authorities to float tenders and fuel rods with hectic construction activity. The award major construction contracts movement of construction equipment necessary at that stage. “This helped,” and machinery – trucks, bull-dozers, says Mr. Agarwal “to reduce the mixers, trailers and so on – compose a mobilisation period”. twenty first century musical note being played against the blue waters of Gulf The construction, of this biggest The Reactor Pressure Vessel (RPV) is of Manar. The mood at Kudankulam nuclear power plant both in terms of its the heart of the plant Directorate and project site is up beat. all photos by : A.I. Siddiqui

Frequent crop failure and poor soil conditions has left not many options for the people in Kudankulam. Fishing and ‘beedi making’ with low monetary returns are the main occupations

38 Nu-Power The project schedules are being Voda Energo Reactor” implying ‘water reactors and several other facilities set- implemented and monitored cooled water moderated’ reactor which up to validate the design, models and meticulously with clock-work precision. is similar to its counterpart ‘pressurised codes. According to the International The first milestone of completion of raft water reactors’ (PWRs) in the United Atomic Energy Agency, 51 units of of the reactor building No-1 has already States and Western countries. The VVERs having a capacity of 32834 been achieved well ahead of the developmental work of the VVER MWe are operational and eight units schedule. And the raft of with a capacity of 6438 the second unit which The vision is in his sight MWe under construction. was scheduled for India has chosen 1000 completion next year has ‘‘Large capacity reactors MWe capacity reactors now been preponed to being set-up at like the two VVERs at September this year! Kudankulam. Kudankulam are add-ons Most of the labour force, and will help to rapidly “VVER” has several says Mr. Agarwal, “is increase the installed variants identified by drawn from the adjoining nuclear capacity in the English alphabet ‘V’ areas”. Strictly speaking country.’’ followed by a 3-digit not a single household number. For instance, V- has been displaced from 187 was the earliest, a pilot the Kudankulam site. Dr. V.K. Chaturvedi design followed by V-338 Moreover, “as per the and V-320. Majority of the CMD, NPCIL government norms there operating nuclear plants is absolutely no project photo: A.I. Siddiqui belong to V-320 category. affected population (PAP). However, as began way back in 1950s in the Then came the advanced designs, V- per NPCIL’s policy preference for the erstwhile USSR and the first VVER 413, V-392 and V-428. Among these, employment is given to the suitably became operational in 1964. All V-392 has the most advanced design qualified personnel whose land has through these years, spanning over features and it is this design which is been acquired and those from the four decades, the design has being supplied to India and set-up at neighbouring areas,” Mr. Agarwal considerably been evolved with Kudankulam. informs. He points out that instructions significant improvement in safety have been issued to the contractors to features. The design is backed-up by The advanced reactors have evolved employ the local labour force to the strong research and experiment base from hundreds of reactor-years of maximum extent. in the Russian Federation. These operation experience, incorporating experiments and research are carried- features that significantly enhance “VVER” in Russian stands for “Voda out in the experimental research safety and performance and minimise

Most of the Labour force employed at Kudankulam comes form the adjoining areas to the project.

An International Journal of Nuclear Power - Vol. 16 No. 1-2 (2002) 39 environmental impacts of the nuclear inlet and outlet, respectively, connected necessary to inhibit boiling of the plants while still maintaining economic to the upper part of the RPV. The coolant. Pressuriser, another competitiveness. Inherent safety coolant, in this case light water, enters equipment cylindrical in shape, is features of the plant and passive and through the inlet, removes the heat employed to build the coolant pressure active engineered safety features make from the core produced in the nuclear up and maintain it within the the advanced reactor top of the rank fuel by the fission chain reaction and predetermined margins. The RPV sits among the entire gamut of reactor the hot coolant moves through ‘outlet’ inside a strong concrete pit. The outer designs (see additional resources at to the steam generators. The light water surface of the RPV is insulated and the end of this article). is demineralised to eliminate the ill cooling is provided in the space effects of minerals naturally present in between the RPV and its concrete A unique feature of the advanced re- the water. A fixed quantity of boric acid housing. actor designs is that they incorporate is also added to this demineralised what are called ‘passive safety Several components, collectively features’, besides the active called reactor internals, are safety features. The passive housed inside the RPV. The ‘core VVER is an advanced safety systems work on the barrel’ accommodates the design and one of the never failing forces of nature like reactor core. The core barrel has safest in the world gravitation, convection, conduc- perforations at the bottom. The tion, momentum etc. We shall S.K. Jain, coolant entering through the return to these features later in Director, (Light- upper portion of the RPV is the article. Water Reactors and directed downwards and enters Kudankulam) the core barrel through these The heart of the Kudankulam perforations. The coolant

nuclear power plant is a 19.47 photo: KTM Kumar circulates through the reactor meter high and 4.5 meters in core before its exit from the RPV. diameter, reactor pressure vessel water which acts as ‘moderator’ and The other reactor internals include, (RPV) (see Figure). The 200-mm thick also a reflector. The boric acid being a ‘Protective Tube Unit’ that keeps the cylindrical vessel is made of low alloy neutron absorber helps to control the core in position and guides the control high strength steel with an inner reactivity, i.e. the rate of fission chain rods into the core; core baffle - cladding of austenic stainless steel. The reaction. sandwiched between core barrel and RPV houses the reactor core, the core - for shielding the RPV from reactor control rods and host of other The RPV has a detachable top cover. irradiation, support systems for fuel mechanisms and connections. The The vessel head is a leak tight chamber assemblies, instrumentation and coolant entry and exit is through coolant facilitating building-up of pressure control, provisions for the placement and retrieval of specimen that are irradiated etc.

The enriched uranium fuel pallets encapsulated in Zirconium–Niobium (Zr-Nb) tubes are assembled in a hexagonal array fuel assembly. The fuel assembly has 331 tubes in all. The Zr-Nb tubes loaded with fuel are placed in 311 locations whereas the balance 20 are used to house control rods and instrumentation tubes. One central tube is for structural element of the fuel Guiding channels for Center tube for assembly frame. Such 163 fuel Control rod Fuel rods instrumentation assemblies constitute the reactor core, which itself has a hexagonal array. The Fuel Assembly Profile

40 Nu-Power How Does it Work ?

Heat in a nuclear power reactor is produced by the controlled fission chain reaction in the nuclear fuel. The heat is used to raise steam that drives turbo-generator to produce electricity. In VVER, slightly enriched uranium is used as fuel. The fuel bundles are placed in the reactor core, which is housed in reactor pressure vessel (RPV). In VVER, water is used both as coolant and moderator. The coolant removes the heat from the reactor. The reactor plant has three major loops. The coolant circuit, or nuclear steam supply system (NSSS) comprises of the reactor itself, primary coolant pump, steam generator and associated pipes and valves. Four such circuits are connected to the RPV (see figure below). Since the boiling point of water is 100 ºC and the temperature of the coolant rises to 322 ºC in the reactor, the coolant is kept pressurised to inhibit its boiling, by a pressuriser, connected to one of the loops. The water in the primary circuit is slightly radio-active, therefore, the close loop is kept isolated from the environment.

1 -Reactor The hot coolant transfers its heat in the steam generator to 2 -Steam generator 3 -Reactor coolant pump (RCP) water circulating in another loop called secondary cycle. 4 -Main coolant pipeline (MCP) 7 5 -Pressurizer 6 -Relief tank Thus, the steam generator has two sides, the primary and 7 -Emergency core cooling system accumulators (ECCS) 8 -ECCS pipelines the secondary side. The secondary circuit comprises steam

8 generators, turbines, moisture separator and reheater, 5 2 6 3 condenser, feed water pump, dearators, associated pipelines and other equipment. The secondary circuit does 2

3 not contain radioactivity, though it is also a closed loop and isolated from the environment.

4 1 The steam produced in the steam generator is fed to a set of turbines, which drive the generator to generate electricity. The steam from the turbine is exhausted into a condenser where it is cooled and condensed. The condensate is pumped back to the steam generator. The condenser cooling is accomplished by a third loop, condenser-cooling system, which draws cooling water from the Gulf of Manar. It is this (third) circuit which is exposed to the environment.

An International Journal of Nuclear Power - Vol. 16 No. 1-2 (2002) 41 The language that nuclear engineers (a) speak Atom: A particle of matter which cannot be broken up by chemical means. Atoms (b) have a nucleus consisting of positively- (d) Inner charged protons and uncharged neutrons Containment of the same mass. The positive charges (e) Outer on the protons are balanced by a number Containment of negatively-charged electrons in motion around the nucleus. (c) Chain reaction: A reaction that

The Russian Dolls (MATRYOSHKA) (left) and concept of dense-in-depth. The fuel maxtrix (a) prevents stimulates its own repetition, in release of fission products to fuel element cladding (b) that prevents its release to the coolant of primary particular where the neutrons circuit (c). The primary circuit (c) prevents release of fission products to inner containment (d) that does not allow its release to the outer outer containment (e) The outer containment is the final barrier to release originating from nuclear fission cause an of fission products to the environment though an exclusion zone and a sterilised zone too exist (see text) ongoing series of fission reactions. The top of the RPV is crowned with to ‘control rod drive mechanism’ and Cladding: The metal tubes containing 121-reactor control drives. The control acts on a diverse principle. The oxide fuel pellets in a reactor core. rods containing neutron-absorbing system injects highly concentrated materials control the rate of chain boric acid into the reactor coolant Control rods: Devices to absorb reaction, in other words, the power of circuit. One boric-acid solution tank is neutrons so that the chain reaction in a the reactor. These rods are held by connected to each four primary reactor core may be slowed or stopped electro-magnetic clutches, giving the coolant pumps. Once the system by inserting them further, or accelerated mechanism its name ‘electromagnetic receives the signal of failure of the by withdrawing them. control rod drive mechanism’. The control rod drive mechanism, it is control rods can be inserted-in, in a automatically actuated. A unique Coolant: The liquid or gas used to stepped manner, allowing absorption of feature of the system is that it can work transfer heat from the reactor core to the neutrons by them. It leads to a even in case of failure of power to the steam generators or directly to the deficiency in the availability of neutrons pumps. It has been made possible by turbines. in the core to reduce the number of the flywheel provided with each pump. Core: The central part of a nuclear fissions thus reducing the power of the The flywheel conserves energy reactor containing the fuel elements and reactor. Conversely, withdrawal of the (inertia, to be accurate) and keeps the any moderator. control rods allows building-up of extra pumps rotating, as the power fails, for neutrons causing more fissions and a duration sufficient to inject the boric Critical mass: The smallest mass of increasing the power of the reactor. In acid into the circuit. fissile material that will support a self- case necessity arises to shutdown the sustaining chain reaction under specified reactor in an emergency or failure of The reactor pressure vessel is conditions. power supply that keeps the connected to four steam generators electromagnetic clutches energised, directly and the coolant returns via Criticality: Condition of being able to the clutches are de-energised allowing main circulating pumps (see the box sustain a nuclear chain reaction. the control rods to fall freely into the ‘how does it work’). These pumps, four Enriched uranium: Uranium in which reactor core under the force of in number, one for each steam the proportion of U-235 (to U-238) has gravitation and the reactor becomes generator, evacuate reactor coolant sub-critical. The action takes only 2 to from the steam generators and inject been increased above the natural 0.7%. 4 seconds to be completed. it into the RPV. Once the heat of the Reactor-grade uranium is usually coolant is transferred to light water to enriched to about 3.5% U-235, weapons- Another fast acting system to shut- raise the steam, the coolant is flowed grade uranium is more than 90% U-235. down the reactor is ‘quick baron back by the circulatory pumps to the Fission: The splitting of a heavy nucleus injection system’. It is a back-up system RPV. This makes a closed loop, also

42 Nu-Power called the primary circulation circuit or have provisions for an auxiallry feed into two, accompanied by the release of the nuclear steam supply system water supply should the main feed a relatively large amount of energy and (NSSS). It is kept isolated from the water supply is disrupted in an secondary system because the coolant abnormal condition. The emergency usually one or more neutrons. It may be in the PHT carries slight radioactivity. heat removal from the secondary side spontaneous but usually is due to a is accomplished by an emergency cool nucleus absorbing a neutron and thus The purification of coolant is down system powered by Diesel becoming unstable. necessitated to control its radio-active generators. The system comprising of Fission products: Daughter nuclei contamination and various chemical heat-exchangers and pumps and is a resulting either from the fission of heavy impurities. The later could lead to closed loop system using the inventory elements such as uranium, or the clogging of system, impairing its heat of steam generators thus requiring no removal efficiency and possibility of feed-water. radioactive decay of those primary corrosion though the entire primary daughters. Usually highly radioactive. circuit is made of corrosion resistant The steam so produced is fed to a set Fuel assembly: Structured collection of stainless steel. The coolant purification of turbines comprising of one high- fuel rods or elements, the unit of fuel in system involves a closed loop circuit pressure and three low-pressure a reactor. with a heat exchanger to bring down cylinders. The steam first passes its temperature and then to ‘cationic’ through high-pressure cylinder and is Chain reaction: A reaction that and ‘anionite’ then routed stimulates its own repetition, in filters before toparticular where the neutrons it is pumped We will make all equipment originating from nuclear fission cause back to the out efforts to called an ongoing series of fission reactions. primary compress the moisture coolant gestation period of separator Cladding: The metal tubes containing circuit. the project and reheater oxide fuel pellets in a reactor core. to remove Control rods: Devices to absorb The steam the moisture S.K. Agarwal neutrons so that the chain reaction in a generators Project Director and reheat reactor core may be slowed or stopped to be used at (Kudankulam) the steam. It Kudankulam then enters by inserting them further, or accelerated project are photo: KTM Kumar the low- by withdrawing them. horizontal ‘shell and tube’ type heat pressure turbines. The impinging Coolant: The liquid or gas used to exchangers. A nest of u-shaped tubes steam on the turbine blades rotates the transfer heat from the reactor core to the is housed inside the shell. The reactor turbine, which is coupled with a steam generators or directly to the coolant flows through the tubes while generator to generate electricity. turbines. light water used to raise steam, called secondary side water or feed water The turbine of Kudankulam plant Core: The central part of a nuclear remains on the shell side. The revolves 3000 times in a minute. The reactor containing the fuel elements and horizontal steam generators hold large turbine is equipped with systems like any moderator. quantity of secondary side water, which stress evaluator and an on-line acts like a large reservoir even if the performance monitoring system that Critical mass: The smallest mass of feed water supply is terminated in an keeps a check on its health. The 24- fissile material that will support a self- unlikely situation. The horizontal layout kilo Volt (kV) generator is capable to sustaining chain reaction under of the steam generator has another operate, at full load, at 5% frequency - specified conditions. advantage that even with significant and voltage variations. Criticality: Condition of being able to reduction in the level of the secondary sustain a nuclear chain reaction. side, the heat removal capacity of the The electricity generated at steam generator is not impaired. These Kudankulam site will be fed to a switch- Fission: The splitting of a heavy nucleus steam generators also have large yard and then to the Southern Grid into two, accompanied by the release of evaporation surfaces implying low through three double circuit lines of 400 a relatively large amount of energy and steam velocities. The steam generators kV and a double circuit line of 230 kV

An International Journal of Nuclear Power - Vol. 16 No. 1-2 (2002) 43 designs. It has several inherent and engineered — usually one or more neutrons. It may be both active and passive — spontaneous but usually is due to a safety features for normal as nucleus absorbing a neutron and thus well as abnormal conditions, becoming unstable. (See the exhibit, Fission products: Daughter nuclei ‘Implementation of the resulting either from the fission of heavy dirversity principle to ensure main safety functions in elements such as uranium, or the VVER-1000 design). Says, radioactive decay of those primary Mr. Jain, ‘the VVER-392, has daughters. Usually highly radioactive. a negative power co-efficient. Fuel assembly: Structured collection of It means that any abnormal fuel rods or elements, the unit of fuel in increase in reactor power that a reactor. could affect the safety of the reactor is self-terminating’. Fuel fabrication: Making reactor fuel Mr. Jain explains that this assemblies, usually from sintered UO2 happens because with an pellets in zircalloy tubes, comprising the abnormal increase in power, fuel rods or elements. the moderator is also heated and becomes less dense, Light water reactor (LWR): A common therefore, loosing its nuclear reactor cooled and usually moderation efficiency. He moderated by ordinary water. photo: A.I. Siddiqui points out another inherent A huge ant hill: the Kudankulam area Low-enriched uranium: Uranium has many like this. safety feature, called enriched to less than 20% U-235. (That ‘negative void coefficient’ in in power reactors is usually 3.5 - 4.5% transmission system. The switchyard reactor physics parlance. It implies that is made indoors to protect it from the the chain reaction in the reactor core U-235.) saline atmosphere of Kudankulam. comes to a grinding halt in an unlikely Megawatt (MW): A unit of power, = 106 (The switch yard at Madras Atomic event of the loss of coolant (water) from watts. MWe refers to electric output from Power Station too is indoor for the the reactor (discussed later in the a generator, MWt to thermal output from same reason). The 400 kV lines will be article). a reactor or heat source (eg the gross connected to Madurai, Trivandrum and heat output of a reactor itself, typically Udhumalpet and 230 kV line to These reactors follow the design Tuticorin. The system also feeds power philosophy of ‘defence-in-depth’ and three times the MWe figure). supply to the station for both the normal provide successive levels of safety so Moderator: A material such as light or operations as well as to start the that failure of one does not impair the heavy water or graphite used in a shutdown plant up. The southern states overall safety of the reactor (See the reactor to slow down fast neutrons by benefiting from the grid include Tamil exhibit ‘Defence-in-depth’). In case of collision with lighter nuclei so as to Nadu, Kerala, Andhra Pradesh and failure of first level, the next protective expedite further fission. Karnataka States. Mr. Jain says that the level comes into force actuating certain capacity of the Southern Grid was safety systems. The reactor protective Natural uranium: Uranium with an adequate for the 1000 MWe capacity systems are 100 per cent isotopic composition as found in nature, units. He also points out that the Central quadruplicated, i.e. four independent containing 99.3% U-238, 0.7% U-235 Electricity Authority (CEA) has channels for such systems exist though and a trace of U-234. Can be used as conducted study to examine the grid- only one was sufficient for the fuel in heavy water-moderated reactors. related issues before the clearance of protection of the reactor. the project by it. Neutron: An uncharged elementary These systems not only have adequate particle found in the nucleus of every The Kudankulam reactor is considered redundancy but also diversity and atom except hydrogen. Solitary mobile one of the safest new generation physical segregation. Diverse systems

44 Nu-Power are employed to achieve the same from steam water liberating hydrogen. safety function to avoid common mode The hydrogen so produced could catch neutrons travelling at various speeds failure. For instance, power supply to fire or explode, depending on its originate from fission reactions. Slow safety related systems and equipment concentration in the air. Thus, at the (thermal) neutrons can in turn readily is provided by more than one grid end we have a scenario like this - a cause fission in nuclei of “fissile” feeders which is backed-up by on-site double ended guillotine break in the isotopes, e.g. U-235, Pu-239, U-233; coolant line with coolant draining from quadruplet (4 x 100) Diesel generators and fast neutrons can cause fission in and then again by a battery bank. the core, the rising temperature of the nuclei of “fertile” isotopes such as U- fuel, radioactive materials including fuel 238, Pu-239. Sometimes atomic nuclei The engineered safety features are melting and flowing on the reactor floor designed to prevent and limit the like magma and zirconium liberating simply capture neutrons. accidental conditions and to mitigate hydrogen from steam which catches Nuclear reactor: A device in which a the abnormal conditions including fire or detonates. The molten uranium nuclear fission chain reaction occurs highly improbable severe accidents. has a higher temperature than most of under controlled conditions so that the These safety features for the V-329 the materials that it encounters in its heat yield can be harnessed or the plant have evolved from the proven V- passage. As a result, all these materials neutron beams utilised. All commercial 320 serial model. The degree of are damaged too. At the same time, reactors are thermal reactors, using a redundancy has been increased in V- perhaps, there is no power supply moderator to slow down the neutrons. 392 from triplicated safety systems to available, of what so ever kind - that is, quadruplicated safety system, as we have a station black-out. Pressurised water reactor (PWR): The mentioned earlier. This additional most common type of light water reactor The loss of coolant will impair the margin provides an opportunity to the (LWR), it uses water at very high plant operators to service and maintain removal of fission heat from the core. pressure in a primary circuit and steam one of the redundant system, according However, water being both coolant and is formed in a secondary circuit. to the procedure, while the plant is in moderator, loss of coolant also means operation that sufficiently relaxes the loss of moderator. Therefore, the chain Radiation: The emission and maintenance intervals. reaction is terminated immediately. propagation of energy by means of However, heat continues to be electromagnetic waves or particles. (cf One can conceive several generated by the radioactivity of the ionising radiation) apocalyptical scenarios of a nuclear fuel. The heat could be large enough, accident but the worst considered by if no alternative safety system exists, Radioactivity: The spontaneous decay the nuclear engineers is an accident to meltdown the reactor core and of an unstable atomic nucleus, giving called ‘loss of coolant accident’ or its escape of radioactivity into the rise to the emission of radiation. acronym LOCA. In such an accident environment in absence of adequate Reactor pressure vessel: The main steel engineers consider a double ended reactor containment. The radioactive vessel containing the reactor fuel, guillotine break in the largest pipe line cloud emanating from the core could moderator and coolant. of the nuclear steam supply system, the travel miles and miles with no respect system that removes fission heat from to political boundaries. Spent fuel: Fuel assemblies removed the reactor core through coolant. A from a reactor after several years use. nightmare for the designers, the very Is n’t it a very imaginative script? low probability accident, can further be Engineers have tried to map such Uranium (U): A mildly radioactive compounded with other misfortunes scenarios through complex calculations element with two isotopes which are like non-availability of power or a few and computer modeling. The chance fissile (U-235 and U-233) and two which operator’s mistakes. LOCA could of such an accident-involving core melt are fertile (U-238 and U-234). Uranium trigger a series of imaginative disasters down but with no release of is the basic fuel of nuclear energy. no less than a Hollywood horror film. radioactivity to public domain is no Waste: For instance, Zirconium present in the more than ‘10-5’ per reactor-year and Zirconium-Niobium tubes has high that of release of radiation beyond the High-level waste (HLW) is highly affinity for oxygen and it may react with reactor, involving mass evacuation still radioactive material arising from -7 steam, under certain conditions. The lower, ‘10 ’ per reactor-year, to be nuclear fission, requiring both shielding chemical reaction will remove oxygen precise. Numbers like ‘10-5’ and ‘10-7’

An International Journal of Nuclear Power - Vol. 16 No. 1-2 (2002) 45 and cooling. It can be recovered from reprocessing spent fuel, though some countries regard spent fuel itself as HLW. It requires very careful handling, storage and disposal. Intermediate-level waste (ILW) is sufficiently radioactive to require shielding, some is categorised as long- lived ILW and this may be disposed of with HLW. Low-level waste (LLW) is mildly radioactive material which does not require shielding in handling or storage, and is usually disposed of by incineration and shallow burial. photo: A.I. Siddiqui Zircaloy: Zirconium alloy used as a tube ‘The lonely survivor : a huge banyan tree is the only one at Kudankulam site. Project authorities are trying to preserve this ‘exception’ to contain uranium oxide fuel pellets in a reactor fuel assembly. are extremely small, difficult to endanger life on the earth. Moreover, (Source: World Nuclear Association, comprehend through day-to-day the earth’s orbit passes through the reproduced with permission) experience. Let’s draw an equally orbits of several such objects. imaginative analogy to understand the population. Clearly, these are highly remoteness of such an event. The impact of such bodies hitting the improbable events. Let’s now examine earth could be varying from almost how is this safety level achieved? On a clear night sky, on a no-moon day negligible to mass destruction, even and away from the city lights one can extinction of civilization, depending on To begin with, a nuclear power reactor observe ‘shooting stars’ or meteors. the size of the object hitting the earth. should have a sound design based on The number of such events is so high The probability of such large-scale proven technology like VVER-392. The on some particular days during the year impacts in a year or in our lifetime is safety margins in reactor design are so that the phenomenon is called a very slim. Dr. Clark R. Chapman, of large that it is said that an aeroplane ‘shower’, a meteor shower. The Southwest Research Institute in US designed on such safety margins will meteoroids, the small debris, mostly of Congressional Hearings on May 21, never be able to fly. Second, nuclear the size of grains or small pebbles, hit 1998 stated, “those chances are small industry follows exacting quality the earth’s atmosphere in hundreds that they are difficult to standards and these standards are and thousands every day. But they comprehend…” maintained through all phases of burn as they pass through the earth’s reactor design, manufacturing, resisting atmosphere leaving behind a Returning back to our query, how construction and operation. Third, trial of fire and presenting a spectacular significant (or insignificant) is the nuclear power plants are operated by celestial show. However, a fraction of number 10-5 ? Well, C.R. Chapman and well-qualified operators trained and large meteoroids reach the earth and D. Morrison in their study published in qualified on simulators where situations many such pieces can be seen in 1998 calculated that the chance of like LOCA are also simulated. The skills museums. Then, there are asteroids dying from an asteroid or comet impact of the operators are tested and an orbiting the Sun between the orbits of is 1 in 20,000 or 2 x 10-4 which is five operation certificate is granted by the Mars and Jupiter, and the comets that fold more than the frequency of reactor regulatory body. The operators are follow a highly elongated orbit around core melt down and 500 times more periodically re-trained and re-qualified the sun. There are hundreds and than the frequency (10-7) of the reactor to hone their skills, responses and thousands of such objects that accident involving evacuation of reflexes. These operators follow well-

46 Nu-Power for a longer period. The HP system is Hurricanes, operated in case of a small and LP REACTOR tornadoes CONTAINMENT system in case of large size rupture in the coolant pipe line. These pumps Airplane crash draw borated water from the spent fuel tank and spent fuel pond in the reactor building. As this water is drawn from the pond and pumped into the reactor core it is discharged through the break Shock wave on to the reactor building floor. It is collected in the floor sump and re- circulated by the active ECCS. Floods

Seismic impacts In our LOCA scenario, we also envisaged flow of molten uranium fuel and liberation of hydrogen that may laid procedures even for emergency independent nozzles. The either detonate or deflagrate. In VVER situations, that is, in abnormal accumulator tanks located within the a ‘melt-fuel catcher’ has been provided conditions the operators don’t panic reactor building and at an elevation at the bottom of the RPV pit. The main and know the course of the action. In above the RPV, have a capacity two purpose of the ‘fuel catcher’ is to bring nutshell, an extreme event like ‘LOCA’ times the volume of water in the RPV. down the temperature of uranium fuel in itself is highly improbable. Each tank is pressurised with (the melting point of uranium is 2800 nitrogen gas occupying about 10 m3 °C, which is, more than the melting Coming back to the sequence of of the total volume of tank and point of steel) and to contain it. The fuel events, the fission chain reaction is connected to RPV through a check catcher, a tank, is made of steel stopped immediately, as mentioned valve and associated piping. The surrounded by water. Bricks of ferrous earlier, with the draining of the coolant moment, the pressure of coolant falls oxide and aluminium oxide are filled in which also acts as moderator. below a pre-determined value (that the tank. These bricks absorb most of However, the heat due to radioactive is, less than the tank pressure) the the heat from uranium, though they material in the fuel must be removed. check-valve opens up and borated themselves are melt during the The job is accomplished by an water gushes into the core. ‘emergency core cooling system’ process. Over a period of time, the (ECCS) by pumping and re-flooding the But then there is another passive molten fuel and the bricks form a lump. reactor core with water. But, one may system holding about 1000 m3 water The composition of these bricks and the ask that recharging core with water (i.e. which slowly discharges the water. design of the ‘melt fuel catcher’ has moderator) could resume the chain Thus, it keeps the core flooded and been decided after extensive research reaction. To avoid this, boric acid, 16 cooled, in case of station black-out, at the world’s one of the largest grams per litre, is added to the ECCS for 24 hours. The system called experimental facility at Kurchatov water. second stage hydro-accumulator Institute in the Russian Federation. system, comprises of eight tanks Millions of dollars are spent to carry out The ECCS has two major categories, placed inside the reactor building at such experiment at this facility by a the passive ECCS and active ECCS. an elevation above the RPV. group of countries. The passive ECCS does not require any pump or power supply and can Besides, the passive ECCS is The hydrogen formed by chemical function during the station black out backed-up by an active ECCS reaction of zirconium with steam is condition also. It is the passive part of comprising of 4 channels of high managed by another system. The ECCS which comes into action first, to pressure (HP) and 4 channels of low Kudankulam reactor is equipped with tide over the initial period of an accident pressure (LP) subsets. A set of one ‘hydrogen recombiners’. The like LOCA. Four accumulator tanks, HP and one LP is connected to one recombiners use ‘palladium’ metal, each with a total volume of 60 m3 are Diesel generator. The system is which acts as a catalyst to recombine directly connected to the RPV through designed to remove the residual heat hydrogen with oxygen. The hydrogen recombiners, fixed inside the upper

An International Journal of Nuclear Power - Vol. 16 No. 1-2 (2002) 47 portion of the inner-containment dome, containment. The reactor building to ensure prevention of any leakage are also a passive feature that does not containment system acts not only as into the environment. Radiation level, need any power and remain ‘on’ all the the final physical barrier to prevent any temperature, humidity etc. inside the time. release of fission products into the reactor building is maintained within the environment during accident conditions acceptable limits by a reactor building It can be visualised that a considerable but it also protects the inner ventilation system. quantity of water must have been converted into However, it can be ar- steam, exerting pressure gued that the penetra- on the inner containment. tions through the reac- The steam so produced tor containment sys- will also be contaminated. tem could become vul- The reactor at nerable in accident Kudankulam has the pro- conditions. The vision of containment Kudankulam reactor is spray system. Essentially equipped with contain- it has two redundant chan- ment isolation system nels of sprinklers that which isolates the spray water, mixed with penetrations (like chemicals to bind the fis- pipeline transporting sion products. The sprin- steam to turbine) used kler system is automati- during normal plant cally activated the moment photo: A.I. Siddiqui operation. This con- Kavalkinaru junction is a very windy spot where stands this windmill park pressure inside the containment integrity is tainment transgresses the achieved by automatic predetermined value. The sprinklers containment and the nuclear system closure of isolating valves under acci- are placed in such a manner that the from the external hazards (See the dent conditions. entire containment is covered evenly. exhibit, ‘‘Reactor Containment’’). The containment system based on ‘dome- In short, all the disastrous events Another feature of the Kudankulam inside-dome’ concept comprises of an arising from the highly improbable plant is a system dedicated to venting inner and an outer containment. The double ended guillotine break in the of steam from the containment. It also inner containment with a spherical largest pipe of primary heat transport helps in keeping the steam pressure dome is made of pre-stressed cement system have been fully addressed in released inside the reactor building concrete and houses the entire nuclear the design of the reactor. within the design limits of the system. The inner containment has a Most of these features, in all its containment system during an liner of 6 mm thick carbon steel sheet probability, will never be used during accident. The ‘system of vented and designed to withstand extreme the life time of the plant, though they containment’ releases the steam-gas internal pressure and temperature are always kept intact and up-to-date mixture in a predetermined and effects arising during accident by way of regular high quality controlled fashion through pipelines conditions. into high efficiency scrubber filters that maintenance and periodic inspection remove the radioactive products from The outer containment is made of and testing. The presence of such or the mixture before its release into the reinforced cement concrete (RCC). The similar systems or their absence could environment through stack and outer containment is designed to have profound impact on the safety of maintains the integrity of the protect the inner containment from a nuclear reactor. For example, containment. natural and man-made external existence of such or similar systems hazards like tornado, hurricane, air and the sound reactor design ensured To seal the fate of any release of shock wave, air-craft crash etc. The that not an iota of radioactive substance radioactivity into the environment the space between the two containments released into the environment during entire nuclear steam supply system as also inside the reactor building is the partial core melt down accident at (NSSS) is housed in the double kept below the atmospheric pressure Three Mile Island plant in the USA in

48 Nu-Power the year 1979. On the contrary, bad outer containment. The PHRS with design and absence of similar systems passive ECCS can remove the residual led to release of radioactive substances heat from the core for 24 hours or into the environment in 1986 Chernobyl longer during station blackout situations accident. Such Chernobyl type reactors and also during LOCA with station are gradually being phased out and black-out for 24 hours. safety systems in the existing reactors have been significantly upgraded. Operators’ intervention is not required for the first thirty minutes of an accident Besides, all these hi-tech safety by the provision of these safety features features, the Kudankulam plant has an both passive and active. Therefore, exclusion zone of 1.6 km. radius, as though highly qualified and trained, the an abundant precaution. A well-laid operators get sufficient time for relaxed emergency preparedness programme, decision making under these adverse with the review and approval of the circumstances. regulatory body, exists to meet any such eventuality. A unique feature of the design is a passive system to maintain negative Let’s now return to some other pressure in the annulus between inner innovative features of the Kudankulam the rectangular shaped heat and outer containments. This is plant. One such feature is a ‘passive exchangers are connected to air- achieved by connecting the annulus heat removal system’ (PHRS) useful to ducts(See the exhibit, ‘‘Passive Heat space to the chimney at the top of the remove the heat from the steam Removal System’’). The upper duct is containment. The chimney is heated by generators during a station blackout a chimney like structure to facilitate the hot air coming from the PHRS situation. Imagine that there is no break natural draft. Both air ducts remain described above. A draft is created by in the primary heat transport system or closed during normal operation. The the heating, which maintains the small or large LOCA but for some increase in steam pressure above the necessary vacuum without involving reason the power supply including the set value leads to the opening up of any active components. back-up system fails. In such a the dampers. Now, cool air can enter situation, the heat from the reactor core through the inlet duct and hot air exits The fire hazards have been considered will be removed by ‘thermo-syphoning’ through the outlet duct. The primary and adequately addressed in the and actuation of the passive ECCS. side of the heat exchangers is design, selection of material and connected to the steam generators via operation procedures of the The ‘thermo-syphoning’ is based on the valves, which are kept always open Kudankulam plant. The reactors are principle that hot fluid moves upwards except during the and cold fluid downwards. The hot maintenance of coolant from the reactor core moves heat exchanger. upwards into the steam generators A set of four such which are kept at higher elevation and heat exchangers the cooler coolant downwards to the connected core, thus establishing a natural parallely to one circulation cycle. However, it is another is in turn essential to remove heat from the connected to one steam-generator to keep thermal of the four steam differential and the thermo-syphoning generators. functional. The secondary side of the These heat steam generators in Kudankulam plant exchangers are is connected to air-heat exchangers in placed which the tubes are finned to reject heat circumferentially Ground Reality : The Project work at Kudankulam to the air. The lower and upper part of out-side the begins with a bang.

An International Journal of Nuclear Power - Vol. 16 No. 1-2 (2002) 49

Implementation of the Diversity Principle to Ensure Main Safety Functions in VVER-1000 Design

SAFETY SYSTEM SAFETY SAFETY SYSTEM PASSIVE PART FUNCTIONS ACTIVE PART

s BRINGING REACTOR s FAST BORON PROMPTLY STATE REACTOR INJECTION SYSTEM PROTECTION

s SYSTEM MAINTAINING s HA1x4 REACTOR IN HA2x4 SUBCRITICAL STATE WITHIN WHOLE SYSTEM OF THE 1-ST HIGH PRESSURE TEMPERATURE s AND 2-ND STEPS SAFETY INJECTION RANGE HYDRAULIC SYSTEM

ACCUMULATORS s x4 MAINTAINING PRIMARY CIRCUIT COOLANT SHUT DOWN

SYSTEM OF PASSIVE s INVENTORY IN CORE COOLING SYSTEM HEAT REMOVAL TO THE x4 AT HIGH PRESSURE ATMOSPHERIC AIR SPRAY SYSTEM s

s MAINTAINING COOLANT INVENTORY IN CORE SYSTEM FOR CONTAINMENT AT LOW PRESSURE EMERGENCY HEAT ENVIRONMENT RELIEF REMOVAL THROUGH AND CLEANING LONG-TERM HEAT SECONDARY CIRCUIT SYSTEM REMOVAL AND WITH CLOSED CYCLE

s REACTOR OF OPERATION FOR SHUTDOWN x4 UNLIMITED PERIOD COOLING DURING OF TIME s INITIATING, EVENTS MELT FUEL NOT ASSOCIATED CATCHER WITH LOSS OF COOLANT

s ENSURING SYSTEM FOR CONTAINMENT s ANNULAR SPACE MAINTAINING VACUUM s INTEGRITY VENTILATION SYSTEM AND CLEANING FLUID

IN ANNULAR SPACE s s MINIMIZING RELEASE OF RADIOACTIVE PRODUCTS INTO ENVIRONMENT

50 equipped with an automatic fire fighting removed. The protective tube assembly years. It is shifted to spent fuel bay, system having four independent is also detached. The tope cover of the outside the reactor building after this channels, though one was sufficient. RPV is lifted by an overhead crane and initial cooling period. The water in the supply tank of fire shifted to an assigned place within the fighting system is replenished by the reactor building. The spent fuel from the Radioactive wastes generated during main fire water storage reservoir. core is transported to the cooling ponds the operation of plant could fall in solid, after ascertaining their leak tightness. liquid or gaseous categories or low, in- A large number of parameters of vari- In case the fuel assembly is found termediate or high-level waste catego- ous systems are monitored by differ- leaking it is first hermetically sealed ries (see glossary of terms in this ar- ent instrumentation and control sen- before its transportation to the pond. ticle). The bulk of radioactivity is con- sors. These parameters include, for ex- The remaining two-third fuel tained within the spent fuel. The liquid ample, temperature, pressure, flow assemblies are re-arranged in the core waste is first evaporated in a steam rates, neutron flux, heated evaporator humidity, vibrations, and then com- etc. The instrumen- pacted as a solid. tation and control The vapour so pro- system transmits all duced is con- normal and abnor- densed and the mal conditions to the water used during state-of-the-art cen- the process is re- tralized monitoring cycled within the system in the control plant. The solid room of the plant. In residue is treated most cases, auto- with other solid matic regulation is waste generated in accomplished in ac- the plant. Most of cordance with the the solid waste is design parameters. the contaminated In some other cases, apparel, tools, particularly those re- scrap etc. Mr. Jain lated to nuclear informs that hardly safety systems, the any radioactivity safety system is au- photo: A.I. Siddiqui thus will be dis- tomatically activated Train from Kanayakumari passing through green landscape. charged in the Gulf with information to of Manar. The the control room as described in our as per the design intent. The fresh fuel burnable solid waste is burnt in an es- LOCA example above. These functions which has already been shifted from pecially designed incinerator. The flue in Kudankulam plant are performed by fresh fuel storage area to the holding gases from the incinerator are passed a computerised system. pond is lowered into the vacant through high efficiency filters, which positions. remove all the particulate activity from The refuelling of these reactors is done them. The gases are than discharged once in a year by replacing one-third of The entire operation is carried out in the atmosphere through a 100 m high the core with fresh fuel. In the refuelling under a protective layer of borated stack. The radiation dose released process the top cover of the RPV is water. The reactor pit or cavity is filled though the stack is also accounted for removed after reactor shutdown and with borated water providing more than the calculations of total radiation dis- bringing down its pressure to 3 meter thick layer of water above the charge from the plant. The non-burn- atmospheric pressure and temperature fuel assemblies. The spent fuel from able waste and the residues from the of the coolant to about 60 - 70°C. The the reactor core is stored within the incinerator are compacted and fixed in connections to the top cover are also reactor building for a period of seven non-leachable medium like epoxy and

An International Journal of Nuclear Power - Vol. 16 No. 1-2 (2002) 51 specific type of cement cocrete. It is samples for example, include flora and Acknowledgements: then encapsulated in leak-proof, high fauna, water and air samples etc. In I sincerely thank- integrity containers and then placed in fact, says Mr. Agarwal, the first phase q Dr. V. K. Chaturvedi, CMD, NPCIL; especially designed trenches within the of ESL has already started functioning premises of the nuclear power plant. Mr. S. K. Jain, Director, (KK-LWR); and collecting meteorological and The surrounding area is closely moni- Mr. S. K. Agarwal, Project Director, various other base-line data. Studies tored to ensure isolation of the waste (KK); Mr. Ashok Chauhan, Addi- on the background radiation have from the environment. tional Chief Engineer, Nuclear already been completed. An Safety , KK Directorate, and Mr. N. Mr. S.K. Agarwal says that cooling epideomological survey of the S. Parihar, Additional Chief Engi- water for the condenser will be drawn population living in the adjoining areas neer, Project Management Ser- from the Gulf of Manar and discharged has also been completed. vices KK Directorate, for their valu- back. The temperature difference able time and guidance. q between the intake and out-fall will not According to Mr. Jain, the total radiation I am thankful to exceed more than 7 °C at the point of release to the environment, permissible ATOMSTROYEXPORT, ATOMENERGOPROEKT, OKB discharge, the limit set by the Ministry by the regulatory body, is 25 x 10-5 GIDROPRESS and ROSENERGO of Environment and Forest (MOEF). sieverts per year (sieverts is a radiation “The temperature gradient (rise) rapidly q My sincere thanks to the World dose). However, says Mr. Jain, “the diminishes in a large body of water like Nuclear Association to allow me to actual release from the plant is Gulf of Manar and will not affect the reproduce glossary of nuclear estimated to be much less than 1 x 10-5 marine life or fishing activity in the terms. region” says Mr. Agarwal. sieverts per year”. This release is much less than the natural variation and so Additional Resources: Evidently, the Kudankulam plant small in magnitude that it can not be maximizes the utilization of water measured by the state-of-art 1. Mr. S.K. Jain – “Advance Light Wa- through its closed loop cycles. instruments and is estimated, rather ter Reactors At Kudankulam”, Nu- However, some fresh water is required, theoretically. Power, Vol.12 No.1, 1998. 2. Mr. Novak Valery et al – “Develop- called make-up water, to compensate ment of Improved Safety Reactor the loss of water through the system, I am impressed by the design of VVER- Plant with VVER-1000”, Nu-Power, as also for holticulture and domestic 392 no less than the beauty of land. Vol.12 No.3, 1998. The twin rocks of Kanyakumari and the use. This small quantity of fresh water 3. Mr. R.K. Sinha and Dr. Anil statue of Thiruvalluvar can be seen is provided by a reverse osmosis plant. Kakodkar – “Advanced Heavy Wa- from the Kudankulam site, more clearly The reverse osmosis plant, converting ter Reactor”, Nu-Power, Vo.13 sea-water into fresh water has been with a pair of binoculars. I am lost in No.3, 1999. set-up at the residential township of the comparing the ancient wisdom with the 4. Mr. J. Kupitz and J. Cleveland – Kudankulam Project. The first phase of modern technological innovations. In “Overview of Global Development plant is already operational. either case, it is the prowess of human of Advanced Nuclear Power Plants, mind which leaves an imprint on the And the Role of the IAEA”, Nu- Mr. Agarwal says that a constant vigil sands of time. I return to Mumbai via Power, Vol.14 No.1, 2000. 5. Mr. Bouteille Francois - ‘‘European on the discharge of radiation in air, Trivandrum. As the aeroplane takes off Passive Reactor’’, Nu-Power, Vol. water and land is kept by the the ‘God’s own country’ gradually 14 No. 3, 2000 Environmental Survey Laboratory disappears. Flying high in the sky, I (ESL). The laboratory collects samples realize that perhaps I will receive more A.I. Siddqui is Senior Manager (Corpo- and surveys in an area of 30 km radiation dose between Trivandrum rate Communications) and Editor, Nu- Power. He writes on nuclear power and surrounding the plant to check and Mumbai than the population living issues related to energy, environment and variations, if any, in environmental in close vicinity of the plant in one year. economics (3Es). parameters to ensure its safety. These I murmur, three Cheers to Kudankulam!

52 Nu-Power