Fukushima Daiichi: It May Be Too Late Unless the Military Steps In

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13. Fukushima spent fuel cannot catch on fire or blow up

Led by Will Davis at Atomic Power Review, a group of nuclear bloggers and analysts has crafted response to information posted by Robert Alvarez about spent fuel at Fukushima and the structural integrity of reactor #4.

http://ansnuclearcafe.org/2012/05/16/spent-fuel-at-fukushima-not-dangerous/

Alvarez's first claim is that the reactor building #4 is at risk of collapse. Second, he claims the spent fuel pool could catch on fire.

There are two points to be made. First, Fukushima reactor bldg #4 is not on the verge of collapse. Second, none of the spent fuel pools at Fukushima can catch on fire.

In a piece called Spent Fuel Safer than Asserted published at ANS Nuclear Cafe, a group of nuclear bloggers, writers, and analysts dissected Alvarez's claims and pointed out numerous, serious errors in them.

Reactor Building #4 will not collapse

In the past year TECPO has added massive concrete and steel reinforcements to the #4 reactor. It has removed debris from the building. The building is now stronger than when it was originally constructed 40 years ago. See the blog post at ANS Cafe for the technical details.

Spent fuel pool #4 will not catch on fire

For starters, Alvarez claims there are 10,893 spent fuel assemblies at Fukushima. In fact, there are only 2,724 spent fuel assemblies at all Fukushima reactors and all of them are in conditions which are below the temperature at which fuel cladding could oxidize. The technical details are laid out in the ANS Cafe article.

Alavarez claims, in particular, that if the spent fuel in pool #4 were to lose its cooling water, that the zirconium cladding on the fuel would oxidize and that all of the curies of radioactivity in the fuel would simultaneously be ejected into the open air.

This sequence isn’t possible based on the current condition of the spent fuel at reactor #4 nor is it possible for the other spent fuel stored at Fukushima.

First, the spent fuel isn’t hot enough. It has been out of the reactor long enough that even if all the water was lost, the remaining decay heat would still be below the point of ignition which is 900C for the cladding and 2,880C for the uranium oxide in the fuel.

Second, the fuel has been out of the reactor for more than a year. The fuel has been out of the reactor longer than the point at which it could catch on fire.

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