Subscribe to South Asia Citizens Wire | feeds from sacw.net | @sacw

A murky meltdown

by Praful Bidwai, 17 March 2011

#socialtags
Version imprimable de cet article Version imprimable
articles du meme auteur other articles by the author

Hindustan Times

Praful Bidwai

March 15, 2011

Fukushima in Japan is the global atomic industry’s worst crisis since Chernobyl, and the first nuclear catastrophe watched by the global public almost in real time. This may yet lead to a meltdown not just in Reactor 1 at Daiichi, but also in six other reactors, including Daiichi No 3, which burns a more hazardous fuel (mixed plutonium and uranium oxides) than most reactors do. Even if there is no meltdown, it is clear from the release of Caesium-137, a product of fission of uranium atoms, that Reactor 1’s core has been damaged, and an unspecified quantity of radioactivity released. Reactor 1 has exploded twice and Reactor 3 once, probably from accumulated hydrogen.

Helicopters have detected radioactivity from Daiichi 100 km away. Worse, as technicians struggle to cool down all three Daiichi reactors by pushing seawater, they are releasing contaminated steam and radioactive vapour as a desperate means to prevent a meltdown - a process that experts say could go on for weeks, even months. Meanwhile, the number of people exposed to high radiation doses has climbed to 190 and counting. New concerns are arising, focused on the presence of hundreds of tonnes of hot spent fuel at the tsunami-hit site. In the Daiichi plant, based on General Electric’s Mark I design, the spent fuel is stored on site. Japan’s nuclear crisis seems fated to continue. Daiichi’s vicinity, from where 170,000 people have been evacuated, would become uninhabitable for months, even years.

Japan is special for many reasons. Its 55 reactors produce about a third of all its electricity. They have to follow strict earthquake-proofing construction norms. Japan’s reactor safety standards are considered the best in the world with multiple redundancy: if one system fails, another takes over. In practice, redundancy doesn’t always work. The Daiichi reactors did shut down with the earthquake, as designed. Diesel generators, meant to provide back-up power to cool the still-hot core and control rods (which regulate the fission rate), did kick in, as planned. But they stopped working within an hour, for as-yet-unrevealed reasons.

The core started heating up, precipitating the crisis with a meltdown potential. Everything now depends on whether the multiple containment of a melting core through a heavy steel container, and a thick concrete wall and dome, works or doesn’t.

The Japanese crisis highlights the inherent hazards of nuclear power generation. Nuclear reactors are high-temperature-high-pressure systems in which a fission chain-reaction is barely controlled within a tiny space supercharged with energy. Reactors are both complex, and internally, tightly coupled. A fault in one sub-system like control rods tends to get quickly transmitted and magnified, plunging the entire reactor into crisis.

A loss-of-coolant accident, in which water circulation around the hot core is interrupted for some reason, is always a possibility. So is a meltdown. Such accidents can be triggered by human error or natural calamity. Experts who have designed, operated or licensed reactors agree that all reactor types can undergo a catastrophic accident.

This feature is unique to nuclear power. As public awareness of nuclear hazards has grown, nuclear power has become unpopular the world over. The Japanese crisis could sound the death-knell of the industry globally as nuclear authorities are questioning the assumptions on which they designed reactor safety systems and operating parameters.

We in India must be alarmed: the Tarapur reactors are also Boiling Water Reactors designed by General Electric, the same as Fukushima’s, only smaller and one-generation older, probably with weaker safety systems. We must discard the ’It can’t happen here’ approach and introspect into our nuclear safety record, with embarrassing failures like a 1993 fire at the Narora reactor, the Kaiga containment dome collapse, frequent cases of radiation over-exposure at numerous sites, unsafe heavy-water transportation and terrible health effects near the Jaduguda uranium mines and the Rajasthan reactors.

We urgently need a safety audit of the entire nuclear programme, in which people outside the Department of Atomic Energy participate, pending a thorough, radical review of half-baked plans to rush into nuclear power expansion with untested reactors like Areva’s EPRs at Jaitapur. To begin with, we must impose an immediate moratorium on further reactor construction.

Praful Bidwai is a New Delhi-based commentator and environmental activist. The views expressed by the author are personal.