VT Padmanabhan,* R Ramesh, and V Pugazhendi

Published in Economic and Political Weekly

Summary

The main raw materials used in a nuclear reactor are uranium and water. One 1,000 MW(e) reactor  being set  up Kudankulam requires  3,000 grams of ²³⁵uranium, 2.8 million liters of fresh water and 7.2 billion liters of seawater.  About 0.4 million liters of fresh water is consumed during periods when the reactor is shut down for maintenance or repairs, if there is spent (used) fuel inside the core. Fresh water is also required for removing the decay heat from the spent fuel pool (SFP) till it is reprocessed or the radioactive materials in the spent fuel rods decay sufficiently so that the heat generated is low enough to be dissipated by air circulation. If fresh water is not circulated inside the core and SFP, the fuel rods can melt leading to a radiological emergency. The campus of the Kudankulam Nuclear Power Plants (KKNPP) located on the Bay of Bengal coast in Tirunelveli district of Tamil Nadu does not have adequate reserve of water and an assured fresh water source to effectively cool the reactor.  Commissioning of the reactor in this condition may turn out to be catastrophic.

Introduction

The Nuclear Power Corporation of India Ltd (NPCIL) constructed two 1000 MW(e) pressurized water reactors (PWR) at Kudankulam in Tirunelveli district of Tamil Nadu.  The first unit was to be commissioned in December 2011.  Local communities have stalled the commissioning of the reactor as they fear that the reactor complex is a threat to their lives.  Analysis of the official documents reveals that there is not enough reserve water inside the campus for cooling the reactor cores and the spent fuel pools.

Water requirements of KKNPP

KKNPP requires fresh water as moderator and as coolants.  There are three types of coolants.  The primary coolant removes the heat generated by nuclear fission 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-mineralized, de-ionized fresh water used as moderator and  primary and secondary coolants are in close loop and are condensed by sea water (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 fission products a reactor core needs to be cooled by de-mineralized 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 sufficiently 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 meter (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.[1]  One year after commissioning, once the first refueling of the reactor has been completed, the spent fuel in SFP will also need to be cooled.

History of Kudankulam Nuclear Power Project (KKNPP)

KKNPP was given conditional clearance by the in 1989. According to the Environmental Impact Assessment (EIA), fresh water for industrial purposes was to be brought from Pechiparai reservoir, 65 km North-West 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 7 days requirement of process and drinking water (of capacity approximately 60,000 m³ for 2 units). This reservoir is planned to be located at an elevation of 35 meter which is much above the safe grade elevation of the reactor building.”[2]

While giving its nod to the project, the Atomic Energy Regulatory Board (AERB) made the following conditions regarding fresh water: [3]

• “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 conceptualize schemes at the Detailed Project Report (DPR) stage for utilization of the water from Upper Kodayar reservoir for such an eventuality.”

Source and reserve of water at KKNPP

Before preparing the detailed project and the environmental impact assessment,  NPCIL did neither conduct any study on the assured availability of water in the reservoir, nor did they 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%t less than the expected average.”[4]  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 flash (MSF) and (c) multiple vapour compression (MVC). Bhabha Atomic Research Centre (BARC) has extensive experience in sea water desalination using RO and MSF technologies and no expertise in MVC technology.  Six desalination plants were constructed at KKNPP.  The first two units built by BARC in the KKNPP township based on RO with a combined capacity of 1200 m³ per day takes 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 crores.  As this is the first MVC desalination plant in India, expertise for handling major problems within a short time may be difficult.

Reserve Water.  The daily output of three operating plants (one plant on reserve) will be 7680 cubic meters, sufficient enough to meet the industrial and potable water requirements of two reactors and the personnel.  The campus has a reserve of 11,445 m³ of water in12 tanks.[5]  Of this, 2000 m³ is in fire-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 fire and potable water, KKNPP has a reserve of 8,020 m³, sufficient 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.

The Central Government’s Expert Committee on KKNPP water reserve

According to Muthunayagam et al   “the inventory available in various tanks is adequate for cooling requirement of reactor Plant for at least ten days in case of power failure from the grid even though the regulatory requirement is only 7 days.”[6] The regulatory requirement, according to AERB is for 30 days and not for 7 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) [7]

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 1425 m³, whereas the daily requirement is 1272 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 sterilizing 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 jellyfish, called fouling agents by the industry. With global warming, jellyfish 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 filters (called flumes) to keep marine life out, but a possibly global jellyfish bloom is proving too much for these filters to handle”.[8]

(iii)  Longer term outage of desalination plants.  Though there are several desalination plants in India and BARC is a leader in this field, 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 ten days?  A desalination plant at Minjur near Chennai broke down in 2008 and it took 45 days to repair.  The experts had to be flown in from the Netherlands.

(iv)   Reactor shut down 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[9].  The startup may be delayed by three days.

The first 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.”[10]  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 is 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 the 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: (Oct 19, 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)[11]

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.[12]  Tarapur Atomic Power Station (TAPS) which uses light water as moderator and coolant has an on-campus reserve of 3868 m³ of fresh water.[13]  The reserve water per MW of installed capacity is 12 m³ in TAPS as against 5 m³ in KKNPP.

Conclusion

NPCIL did not do its homework regarding the availability of fresh water at or near the reactor site before signing a contract worth of Rs 130 billion 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 backup for coolant water is insufficient, the commissioning of the reactor will be a dangerous gamble.

We are extremely grateful to the peer reviewer for the criticisms and suggestions on an earlier draft.

REFERENCES