Koodankulam’s Reserve Water Requirements
by Power Engineering – TRANSCEND Media Service
There is not enough reserve water inside the Koodankulam nuclear power plants complex for cooling the reactor cores and the spent fuel pools.
The Nuclear Power Corporation of India Ltd (NPCIL) constructed two 1,000 megawatts (electric) MW(e) pressurised water reactors (PWRs) at Koodankulam in Tirunelveli district of Tamil Nadu. The rst unit was to be commissioned in December 2011. Local communities stalled the commissioning of the reactor as they feared that the reactor complex would threaten their lives. An analysis of the ofcial documents reveals that there is not enough reserve water inside the campus for cooling the reactor cores and the spent fuel pools (CSFPs).
Koodankulam Nuclear Power Project (KKNPP) requires fresh water as a moderator and as a coolant. There are three types of coolants. The primary coolant removes the heat generated by nuclear ssion from the reactor core. Part of the heat in the primary coolant is transferred to the secondary coolant, which is converted into steam that runs the turbine. The de-mineralised, de-ionised fresh water used as a moderator and primary and secondary coolants are in close loop and are condensed by seawater (condenser coolant) drawn from and disposed off in the Gulf of Mannar. About 30% of the heat generated in the reactor core is transferred to primary and secondary coolants and the remainder is absorbed by seawater. Since the spent fuel will contain radioactive decay heat from the ssion products, a reactor core needs to be cooled by de-mineralised fresh water even when no electricity is being generated. Likewise, the spent fuel pool (SFP) will also have to be cooled till fuel rods are reprocessed or the radioactive materials in the spent fuel rods decay sufciently so that the heat generated is low enough to be dissipated by air circulation. The fresh water requirement (evaporative loss) of one reactor is 2,832 cubic metres (m3) during operation and 400 m3 in shutdown mode.
The potable water requirement is 1,272 m3 per day. The total industrial and domestic requirement for two reactors is 6,936 m3 per day (Muthuna yagam et al 2011). One year after commissioning, once the rst refuelling of the reactor has been completed, the spent fuel in SFP will also need to be cooled.
KKNPP was given conditional clearance in 1989. According to the Environmental Impact Assessment (EIA), fresh water for industrial purposes was to be brought from Pechiparai reservoir, 65 km northwest of the site on the river Kodayar, in Kanyakumari district. “At project site, it is proposed to construct a reservoir with a capacity to store seven days requirement of process and drinking water (of capacity approximately 60,000 m3 for two units). This reservoir is planned to be located at an elevation of 35 metre which is much above the safe grade elevation of the reactor building” (NEERI 2003).
While giving its nod to the project, the Atomic Energy Regulatory Board (AERB) made the following conditions regarding fresh water:1
* Facility to store at site adequate quantities of water should be provided to meet the makeup requirements of uninterrupted cooling of core and other safety related systems on a long-term basis.
* Facilities engineered at site should meet the requirements even in the event of possible disruption of piped water supply from Pechiparai dam.
* The safety of the 65 km long pipeline from Pechiparai dam should be ensured by appropriate security arrangement.
* In the unlikely event of the breach of the dam, alternative sources of water supply should be available for the site within a reasonable time.
* NPCIL should conceptualise schemes at the Detailed Project Report (DPR) stage for utilisation of the water from Upper Kodayar reservoir for such an eventuality.
Water Source and Reserve
Before preparing the detailed project and the environmental impact assessment, NPCIL neither conducted any study of the assured availability of water in the reservoir nor did it inform the people who have been using the water from the 120-year-old dam. According to a study, “the district had faced 52 years of drought and drought-like situations during 1901-89. The run-off in the dam during 1963-90 was 15% to 37% less than the expected average” (Ramesh 2006). As of now, there is neither a pipeline from the dams nor an on-campus reservoir with 60,000 m3 of water at KKNPP. Instead, the campus has four desalination plants.
Desalination Plants: There are three different technologies for desalination. They are (a) reverse osmosis (RO), (b) multi-stage ash (MSF), and (c) multiple vapour compression (MVC). The Bhabha Atomic Research Centre (BARC) has extensive experience in seawater desalination using RO and MSF technologies and no expertise in MVC technology. Six desalination plants were constructed at KKNPP. The rst two units built by BARC in the KKNPP township based on RO wit h a combined capacity of 1,200 m3 per day take care of the needs of the township. The other four plants, based on MVC technology, were built by an Israeli company at a cost of Rs 115 crore. As this is the rst MVC desalination plant in India, expertise for handling major problems within a short time may be difcult.
Reserve Water: The daily output of three operating plants (one plant on reserve) will be 7,680 m3 , sufcient to meet the industrial and potable water requirements of two reactors and the residents in the complex. The campus has a reserve of 11,445 m3 of water in 12 tanks (Krishnamurthy et al 2011a). Of this, 2,000 m3 is in re-water tanks and 1,425 m3 is in tanks for domestic use located outside the KKNPP island. The daily requirement of potable water is 1,200 m3. Leaving aside the re and potable water, KKNPP has a reserve of 8,020 m3 , sufcient enough to cool two operating reactors for about one-and-a half days. If there is a problem with water supply, the reactors will have to be shut down and the reserve will last about 10 days.
Committee on Water Reserves
According to Muthunayagam et al (2011) “the inventory available in various tanks is adequate for cooling requirement of reactor plant for at least 10 days in case of power failure from the grid even though the regulatory requirement is only seven days.” The regulatory requirement, according to AERB is for 30 days and not for seven days: “if the minimum water supply required for long-term heat removal from the core cannot be ensured under all circumstances, then the site shall be deemed unsuitable. Availability of adequate quantity of water to maintain the reactor under safe shutdown state for at least thirty days needs to be ensured under all circumstances” (emphasis added).2
The Expert Group is silent about the following issues.
(i) Drinking Water Requirement of the Campus: The reserve water available in two tanks meant to store potable water is 1,425 m3 , whereas the daily requirement is 1,272 m3 . Even if the consumption is reduced when the supply chain breaks down, the reserve may not last for more than two-three days. (Since the industrial water is laced with elements like boron and chemicals, they cannot be used for drinking.)
(ii) Failure of Desalination Plants Due to Causes Other Than Grid Failure: The expert committee considered grid failure alone as the only probable event. If the grid fails, the reactors will shut down automatically and hence the coolant requirement will be about 800 m3 for two reactors. (All reactors rely on grid power for maintaining their safety related pumps and instrumentations as the grid is more reliable than the reactors.) A desalination plant is a complicated machine for cleaning and sterilising a chemically and biologically complex medium. That machine can also fail due to wear, tear and corrosion or due to an attack of marine organisms like jellysh, called fouling agents by the industry. With global warming, jellysh is poised to recapture the empire they lost some 600 million years ago. Their intrusion in desalination plants, ships and power plants has been on the increase during the past couple of years. In July-August 2011, nuclear power plants in Japan, Scotland and Israel were shut down due to their ingress, a feat that half a century of anti-nuclear activism could not achieve. “The plants logically have lters (called umes) to keep marine life out, but a possibly global jellysh bloom is proving too much for these lters to handle”.3
(iii) Longer-term Outage of Desalination Plants: Though there are several desalination plants in India and BARC is a leader in this eld, there is no expertise for MVC desalination technology in India. All the plants in India are based on either RO or MSF technology. In the case of a major defect, experts may have to be brought in from Israel. What if the desalination plants are not brought on line within 10 days? A desalination plant at Minjur near Chennai broke down in 2008 and it took 45 days to repair. The experts had to be own in from the Netherlands.
(iv) Reactor shutdown and the Iodine Pit: If the desalination plants break down, the reactors also will have to be shut down. Unlike other machines, a nuclear reactor cannot be restarted immediately after the shut-down, because of the phenomenon called the iodine pit/xenon poisoning.4 The start-up may be delayed by three days.
The rst project proposal stated that there will be a reservoir with a capacity of 60,000 m3 of water brought from Pechiparai. AERB gave “the clearance for excavation in October 2001 subject to compliance of stipulations like restriction on surface mining of limestone and design of embankment for water storage reservoir as ultimate heat sink”.5 Excavation work for a reservoir was started in 2004. It is not known as to why construction work of the reservoir was not completed. Both AERB and the Expert Group of the central government are silent on this issue. If the reservoir were there, they could have stocked 60,000 m3 of water from four desalination plants (lying idle for the past three years) in six days.
The World of Virtual Water
Quoting NPCIL and DAE sources several stories have appeared in the national media showing that the reactors have enough reserve water. Excerpts from a report that appeared in Times of India: (19 October 2011):
In case of an accident or a natural disaster, the cooling of the core is top priority and drawing lessons from the Fukushima scenario, India’s plants are now supplied by alternate water sources that will not be vulnerable to disruption. “Not depending on on-site water sources alone, water pipelines from remote locations will supplement and provide fall-back apparatus. India has ramped up safeguards at its atomic power plants with three layers of power back ups, water pipes drawn from off-site locations, elevated water towers and options for injecting nitrogen to prevent explosions” (emphasis added) (Deshpande 2011).
KKNPP does not have pipes drawn from off-site locations or elevated water towers. Other campuses do have such pipelines and also higher on-campus reserves of fresh water. Madras Atomic Power Station (MAPS) with two heavy-water cooled and moderated reactors with an installed capacity of 440 MW(e) has 28,400 m3 of fresh water and the campus is augmenting its water reserve with an additional reserve of 750 m3 as recommended by the Fukushima Task Force (Krishnamurthy et al 2011b). Tarapur Atomic Power Station (TAPS) which uses light water as moderator and coolant has an on-campus reserve of 3,868 m3 of fresh water (Bhattacharjee et al 2011). The reserve water per MW of installed capacity is 12 m3 in TAPS as against 5 m3 in KKNPP.
NPCIL did not do its homework regarding the availability of fresh water at or near the reactor site before signing a contract worth Rs 13,000 crore with the Russians. They constructed the KKNPP campus in violation of the terms and conditions laid down by the AERB. NPCIL and elements within the Government of India have been spreading misinformation about the safety of the reactor complex. Since the back-up for coolant water is insufcient, the commissioning of the reactor will be a dangerous gamble.
Notes & References can be viewed at: ( http://epw.in/epw/uploads/articles/17412.pdf )
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