The Economic Times
Wednesday September 26, 2012
The Economic Times
Dismiss safety concerns over Kudankulam
By K S Parthasarathy
On August 9, 2012 Atomic Energy Regulatory Board permitted the Nuclear Power Corporation of India Limited (NPCIL)for fuel loading and first approach to criticality of the first unit of the Kudankulam Nuclear Power Project (KKNPP) with certain stipulations. AERB reviewed the final status and permitted fuel loading. Fuel loading is currently in progress.
Some activists express concern on the Board’s clearance at this stage when, according to them, NPCIL has not fully complied with the requirements mandated by various committees and by the Board itself post Fukushima. One critic felt that AERB did it under pressure from the Prime Minister’s Office! However ,AERB’s decision is based on the consensus opinion of competent specialists in topics such as geology, seismology, reactor safety, meteorology, flood control among others.
The bone of contention is NPCIL’s compliance with the recommendations of the AERB Committee to Review Safety of Indian Nuclear Power Plants against External Events of Natural Origin in a phased manner. The Committee noted that the Kudankulam plant has several advanced safety features including those for ensuring safety against external events of natural origin and for management of design basis as well as beyond design basis accidents. Its recommendations are made as a matter of abundant caution for further safety enhancement. AERB accepted NPCIL’s schedule in that context. AERB shall ensure that NPCIL strictly follows the decided scheme.
This approach is nothing new. In 1994, While reviewing the specialists committee report of the Narora fire incident, the Board determined that that there is a need to examine the turbine roots of all pressurized heavy water reactors (PHWRs) as the incident was initiated by the failure of turbine blades. AERB directed sequential shutting down of all PHWRs to examine its turbine roots and initiate remedial action. The Board did not ask NPCIL to shut down all reactors simultaneously; AERB consulted experts in the field and took the decision based on engineering judgment.
Why nuclear scientists and engineers are convinced that Kudankulam nuclear power plant is very safe? Simultaneous occurrence of a powerful earthquake and a devastating tsunami led to the accident at Fukushima. The conditions in Fukushima do not apply to Kudankulam which falls in a zone of very low seismic potential.
Tsunamis will not affect the plant because systems important to safety are at higher elevations: the pumping station above 7.65 metres; the turbine at 8.1 metres; the nuclear reactor at 8.7 metres; emergency diesel generators at 9.3 metres and Station black out battery at 16.5 metres. Further, the safety-related buildings belong to the highest seismic category and are closed with double sealed, water leak tight doors to prevent seepage of water.
Onagawa nuclear power plant successfully faced the earthquake and tsunami that wrecked Fukushima, 120km away because of its newer design and location on an elevated embankment.
Kudankulam reactors belongs to ‘Generation III Plus’ category; they have the latest safety features (improvement over the currently standardized nuclear power plants which are categorized as Generation II). They have passive systems to remove the residual heat, for flooding the reactor core in case of an accident and to inject boron (a neutron absorber) to shut down the reactor fast in case of an emergency. The reactors have passive hydrogen recombiners to prevent hydrogen explosions.
The chance of radioactivity release from the plant to the environment in an accident is minuscule. Five physical barriers such as the fuel matrix, the fuel cladding, the main circulation circuit and the inner (120 cm thick concrete + a lining of 6 mm steel) containment and outer containment (60 cm concrete ) and other engineered features prevent it. The safety of the reactor is assured because it incorporates a four train safety system; any one of them is adequate to ensure 100 % safety.
A core catcher, a marvelous piece of engineering shall retain solid and liquid fragments of the damaged core, parts of the reactor pressure vessel and reactor internals if there is a severe accident. The vessel shall prevent the molten material from spreading beyond the limits of containment.
The probability of an accident is extremely low because of the advanced safety features of the reactors; even if an accident occurs, no radioactivity will released outside the plant site; there will be no need for evacuation of the public from the surrounding areas.
Kudankulam plant Unit -1, a Generation III plus reactor is very safe as it is. The additional measures will further enhance its safety status. Indian engineers and scientists are convinced about its safety. With the commissioning of the reactor, India will demonstrate its capability to seamlessly absorb advanced nuclear power technology.
[ K S Parthasarathy is former secretary of the safety watchdog, Atomic Energy Regulatory Board.