India's 20 commissioned nuclear reactors are built with adequate earthquake emergency backups and do not suffer from two key factors that appear to have worked against the Fukushima plant, atomic energy scientists and officials said today.
An earthquake of the scale of the one in Japan, followed by a tsunami, would however likely have significantly damaged – if not crippled – the Indian reactors too.
Nudged by the Prime Minister, the Nuclear Power Corporation of India Limited (NPCIL) – the public sector agency that operates all Indian nuclear power plants – said it would review safety at all reactors in the aftermath of the Japan tragedy.
The radiation scare in Japan has also reignited a debate on whether India should continue to aggressively pursue its nuclear power expansion programme, with some physicists and activists demanding a re-look at proposed plants in Jaitapur, Maharashtra.
But Indian reactors appear better prepared for the likely seismic activity in their region than Fukushima, where explosions over the past two days have triggered fears of a nuclear crisis, the scientists and officials told HT.
Reports suggest that the failure of power backups at the Fukushima plant rendered it incapable of cooling, leading to the overheating that ended in the explosions. "I do not know if Fukushima was equipped, but we in India have a reactor design that allows for cooling using convection currents even in a state of Station Blackout – when all power and backups fail," said Indian Institute of Technology Kanpur Professor Om Pal Singh, an expert on nuclear design safety.
A senior NPCIL officer pointed to the age of the Fukushima reactor – it started operating in 1971, and its safety design is based on data from a 1952 earthquake. "In contrast, though some of our reactors like the ones in Tarapur are old, we have been constantly evaluating and reviewing their safety requirements," the official said. The Tarapur reactors were commissioned in 1969 – two years before Fukushima, which was scheduled to be shut down this February but was given a 10 year extension.
Nuclear reactors the world over are built to withstand earthquakes based on the scale of seismic activity expected at the site of the plant. Safety mechanisms also depend on the proximity of a plant to the coast, and on the type of the nuclear reactor – whether it is a boiled water reactor like the one in Fukushima or two reactors Tarapur, or a pressurized water reactor or a pressurized heavy water reactor.
Nuclear reactors have sensors that detect and measure earth movement triggered by seismic activity. The moment the acceleration of the earth exceeds a value known as the operator basis earthquake (OBE), the reactor automatically starts shutting down.
Each reactor is built with a specific OBE and a SSE – a safe shutdown earthquake value that represents the peak ground acceleration (PGA) the reactor can withstand while remaining functional.
Once the reactor starts shutting down, an emergency cooling mechanism is also automatically activated. The core of the reactor – containing the fuel rods of the nuclear source (uranium, thorium or other sources) – must be cooled to avoid a meltdown, a situation where the fuel rods melt. The molten fuel rods can burst through into the containing chamber posing potential radiation risks.
Reactors typically have diesel generators as backups for electricity cuts likely after massive earthquakes. Batteries are also provided to power the cooling mechanism if diesel generators fail. "The convection based cooling is the last resort," Singh said. At least some of the diesel generators are placed at a height in cases where Indian reactors are close to the coast, Pal said, adding that he would not like to comment on specific reactors and their design.
But not everyone is satisfied with the Indian government's claims of safety or its promise of a review of all reactors.
"What needs to be understood is that Murphy's law applies in the case of hazardous projects like nuclear power plants… if something can go wrong, it will go wrong," argued Suvrat Raju, a physicist from the Harishchandra Research Institute in Allahabad, who is opposed to India's forceful push towards expanding its nuclear power programme.
"You can have a number of small shortcomings which put together can lead to a major catastrophe. No other form of power generation poses the kind of risk that nuclear power does," he added, speaking at a media conference called by an anti-nuclear group called the Coalition for Nuclear Disarmament and Peace (CNDP).
The CNDP, other activists and even a former chairman of the atomic energy regulatory board (AERB) – India's nuclear regulator – have questioned claims by the government and the NPCIL on the safety of the country's reactors. They have argued that the NPCIL and the AERB are non-transparent on how they arrive at decisions on suitability of projects like the one in Jaitapur in Maharashtra's Ratnagiri district.
"The AERB and the NPCIL are secretive and evasive on such issues," former AERB chairman A Gopalakrishnan wrote in a newspaper article recently, suggesting that the powerful nuclear power industry was lobbying to push through unsafe projects in India.
The concerns have mounted over recent months particularly over the Jaitapur project, since hundreds of local villagers too have opposed the plant. Opposition parties today raised concerned over the proposed Jaitapur project in the Maharashtra Assembly. The Western Ghats – where Jaitapur is located – is an ecologically sensitive region.
More general concerns also exist over the seismic zone mapping in India, with several experts calling for it to be revisited. Jaitapur, for instance, formally lies in a seismic zone III region, but activists argue that it should be marked as a zone IV region based on the seismic history of the region. The European Power Reactors (EPRs) proposed for Jaitapur are untested and under review in European countries like Britain, Raju said.
"We do not have an independent atomic energy regulator, since the AERB comes under the DAE itself," Praful Bidwai of the CNDP said. Critics are also calling for an independent safety audit of all nuclear installations in India, by a team consisting of experts beyond the atomic energy establishment. Till such an audit happens, the government should stop all nuclear projects, they are arguing.
The 20 reactors already working have a combined capacity of 4500 MW. Another six that are currently under construction will double India's nuclear power production, as they have a combined capacity of 4800 MW. The first of these new reactors – at Kudankulam is scheduled to start commercial operations from this June.
Other reactors planned in West Bengal, Orissa, Haryana, Gujarat and Andhra Pradesh – apart from Jaitapur – are a part of India's goal to increase nuclear power output to 64,000 MW by 2032. Nuclear power currently contributes about 3% of India's power needs, as opposed to about 80 % in France.