Sodium cooled reactors are unsafe

The Economic Times

Fast breeder reactors are the least safe
Swaminathan S Anklesaria Aiyar, TNN Mar 27, 2011, 11.55am IST

Nuclear safety has become a top priority after the Fukushima nuclear disaster in Japan. Safety at all Indian plants is being reviewed, and coastal reactors may be built on higher ground for tsunami protection. Critics have objected to unproven French reactors for the Jaitapur nuclear power complex.

Yet critics and agitators are ignoring the biggest nuclear risk of all: the inherently dangerous nature of fast breeder reactors (FBRs). India’s first prototype 500 MW FBR is about to be commissioned at Kalpakkam, and four more are planned.

The Indian nuclear establishment has long viewed FBRs as a great prize because these are indigenously engineered and can use India’s huge thorium reserves , eliminating dependence on uranium. Problem: conventional reactors are cooled by light or heavy water , but FBRs are cooled by liquid sodium, which is inherently dangerous. Liquid sodium reacts explosively with both air and water. Hence, even a tiny leak of sodium coolant can cause a fire. Fukushima shows that the unexpected can always happen despite precautions. When Fukushima overheated, the Japanese pumped in sea water and bombarded the reactors with water cannon to bring down temperatures. But such use of water would be impossible in any accident at an FBR—the water would react explosively with the sodium coolant. So, the real lesson of Fukushima is that FBRs are inherently risky. FBRs have long been touted as a patriotic feat of self-sufficiency . But they now need the closest scrutiny for safety by an independent agency. Scientists MV Ramanna and Ashwin Kumar say that Indian FBRs are dangerous for other reasons. First, the containment dome is not as strong as in other reactors. Second, they have a positive coolant void coefficient. Both these features bring down the very high costs of FBRs, which so far have proved to be financial disasters globally. But such costcutting comes at a price in safety.

Risks at other reactor sites have been exaggerated. Jaitapur has some seismic risk, but far less than in reactor sites in Japan and Korea that withstood many earthquakes. Indian coastal reactors survived the 2004 tsunami, which hit the Tamil Nadu coast very hard. That lends some credibility to the government’s claims of safety on this count. The French-designed EPR reactor is said by critics to be not proven. Only one such reactor is still at the commissioning stage in Finland, after huge cost and time overruns. However, by definition every new technological advance is “unproven” and that can hardly be a reason for never going forward with new technology. Some critics of the “unproven” Jaitapur design say nothing about similarly unproven indigenous advances. Indian scientists have constantly innovated new and untested technologies and it would be silly to veto them all as unsafe.

However, FBRs are a special problem, as proven globally. The International Panel on Fissile Materials says, “A large fraction of the liquid-sodium cooled reactors that have been built have been shut down for long periods by sodium fires. Russia’s BN-350 had a huge sodium fire. The follow-on BN-600 reactor was designed with its steam generators in separate bunkers to contain sodium-water fires and with an extra steam generator so a firedamaged steam generator can be repaired while the reactor continues to operate using the extra steam generator . Between 1980 and 1997, the BN-600 had 27 sodium leaks, 14 of which resulted in sodium fires… Leaks from pipes into the air have also resulted in serious fires. In 1995, Japan’s prototype fast reactor, Monju, experienced a major sodiumair fire. Restart has been repeatedly delayed, and, as of the end of 2009, the reactor was still shut down.
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France’s Rapsodie, Phenix and Superphenix breeder reactors and the UK’s Dounreay Fast Reactor (DFR) and Prototype Fast Reactor (PFR) all suffered significant sodium leaks, some of which resulted in serious fires.” If FBRs had such problems even in normal conditions , imagine what could happen in an unanticipated disaster like Fukushima.

We cannot trust safety assurances from the nuclear establishment because it cannot be expected to reveal the skeletons in its cupboard . In the US, private sector companies operate nuclear plants while a government agency regulates them and makes sure they are safe. But in India, the same nuclear establishment that designs and operates reactors also handles safety assessment, monitoring and evaluation. Notions of patriotism and secrecy override transparency.

This has to be terrible for safety. We must have an independent body for nuclear safety that can publicly take the nuclear establishment to task. If it finds FBRs are unsafe, so be it. Fukushima has opened our eyes. Let not our monolithic nuclear establishment close them again.

One Response to “Sodium cooled reactors are unsafe”

  1. CaptD Says:

    In short, India cannot afford a Trillion Dollar Eco-Disaster like Fukushima… Especially since Solar (of all flavors) costs are going down monthly while Nuclear and others are going upward!

    Secrecy is the only thing protecting the Nuclear Industry…

    Liked and Tweeted…

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