Nucear safety panel recommends additional design provisions
A high-level committee appointed to review the safety of Indian nuclear power plants says India’s plants are safe, but has suggested reliable back-up provisions to cool reactors and prevent meltdown.
The committee was set up in the wake of the nuclear disaster in Japan, triggered by an earthquake and a tsunami simultaneously hitting the Fukushima nuclear power plant on March 11, 2011 The committee, appointed by the Atomic Energy Regulatory Board (AERB) of India in March, put out the a bare-bones report earlier this month. The final detailed report is still under AERB review.
According to the findings of this committee, design, operating practices and regulations followed in India have inherent strengths to deal with nuclear events and their consequences. In a press statement released on September 5, R Bhattacharya, chairman of Nuclear Power Corporation of India Limited (NPCIL) also says that all nuclear power plants in India periodically undergo safety reviews, which are upgraded when required.
The committee allays apprehensions regarding chances of natural disasters like tsunamis hitting Indian nuclear power plants. “Submarine faults are located quite far, more than 300 km from the western coast and more than 1,300 km on the eastern coast. So, simultaneous occurrence of two natural disasters such as an earthquake with a tsunami (as in the case of Fukushima) is not foreseen for India,” says Bhattacharya.
In the light of Fukushima accident, which showed that occasionally the magnitude of natural events can be higher than what is considered during design, the committee recommends making additional design provisions in nuclear reactors.
To deal with the extended station black-outs in case of severe accidents, the committee suggests that the reliable back-up provisions should be made for addition of water to the primary heat transport system—a network of pipes carrying water around the reactor to keep it cool.
Bhattacharya also asks for review of safety systems to meet the currently revised maximum flood level possibility in nuclear power plants like the Tarapur and Kalpakkam plants in Maharashtra and Chennai. “It is important to shift plant machinery, especially back-up generators, above the flood level to avoid flooding as happened in case of Fukushima,” says R Rajaraman, member of the International Panel on Fissile Materials, a group of independent nuclear experts working on policy initiatives to reduce stocks of enriched uranium and separated plutonium. Rajaraman also recommends that Indian authorities should look into venting. In case of severe accidents, pressure of steam increases inside the reactor; venting is done to release that extra steam. But in case of Fukushima nuclear disaster, the steam had converted into hydrogen which is explosive and caused the blast. “We need to find out how to deal with this problem,” says Rajaraman.
The committee also seeks creation of an emergency facility at each nuclear power plants as severe external events may result in physical isolation of the site, making it difficult for outside help to reach it.
After the review of the report, AERB will pursue NPCIL for its implementation.
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