Fukushima releases one-tenth of those from Chernobyl: France's IRSN
Ann MacLachlan
But Thierry Charles, IRSN's head expert on the Japanese crisis, said at a midday CET briefing there was a "ray of hope" for the beleaguered reactor site, compared with the "very pessimistic" outlook at the same time on Wednesday, because firefighters had managed to spray water onto spent fuel pools whose heat was rising, and Tokyo Electric Power Co. said it expected to restore regular electric power later Thursday to emergency cooling systems for the three reactors whose cores were partly damaged.
Tepco "has regained a certain control over the situation" at Fukushima I, Charles said. "Not everything is under control," he said, noting that it might be difficult to reconnect equipment and that the restored power source might not be completely reliable.
"But it's the first reassuring information we've had since Saturday," he said, referring to the day after when the six-unit Fukushima I site north of Tokyo was hit by an earthquake and subsequent tsunami that knocked out all power sources.
Charles said that if the spent fuel pools at reactors 3 and 4 should be emptied of water, the dose rates on the site would be so high that it would be extremely difficult to work there. But that doesn't seem to be the case, contrary to some reports on Wednesday, he said.
At the site's reactor 3, where a containment breach had been suspected, Tepco has measured pressure in the reactor vessel, a sign that the steam inside is not escaping as had been feared, he said.
But what's important is continuous cooling by any means available of both the reactor cores and the spent fuel pools, he said.
Patrick Gourmelon, IRSN's medical expert, said that there was no need for any member of the public to take stable iodine tablets to avert thyroid cancer, adding that the tablets can create other health problems.
IRSN's calculations are based on the volatile radioelements most important for health impact, essentially iodine, cesium and tellurium.
Chernobyl released about 6 Exabecquerels or 6 x 10 to the 18th becquerels of those elements, according to IRSN. Releases from Fukushima as of Thursday were a little under 7.5 x 10 to the 17th becquerels of those elements.
--Ann MacLachlan, ann_maclachlan@platts.com
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March 17, 2011