Recriticality Suspected at Fukushima Nuclear Site
"Fission taking place in the reactor can lead to increases in radiation emissions and raises concerns about further leaks after another radioactive hot spot was discovered in Tokyo on Oct. 29. It's possible there are similar reactions occurring in the No. 1 and No. 3 reactors, the other cores damaged at the station, Matsumoto said.
“Melted fuel in the No. 2 reactor may have undergone a sustained process of nuclear fission or re-criticality,” Tetsuo Ito, the head of Kinki University's Atomic Energy Research Institute, said by phone. “The nuclear fission should be containable by injecting boron into the reactor to absorb neutrons.”
[Sorry I forgot to include the link to Corbett’s excellent Fukushima Update pages. (Must move it up from the bottom of my bookmarked pages list!) Fukushima Update – Day 237 Good graphics and extensive list of links
There are 4 headline stories at ENENEWS this morning on this story with various experts commenting:
a.. JUST IN: Japan Gov't Confirms Detection of Radioactive Xenon in Reactor No. 2
b.. "A very bad sign": 'Partial' re-criticality is just TEPCO spin -- "We could face…
c.. Kyoto Nuke Expert: This amount of xenon would not be detected unless melted fuel…
d.. Top Japan Nuke Expert: Sustained "re-criticality" of melted fuel may have occurr…
EX-SKF reports TEPCO thinks they can control the small criticality by carefully monitoring temperature and pressure.
More on Xenon Detection in Reactor 2 (TEPCO's Press Conference)
Fuku-I Nuke Plant: Nuclear Fission in Reactor 2? Xenon-133, -135 Detected
The Phyics Forum discussion is very interesting.
Most importantly, It may be the Xenon gas is being emitted by plutonium in the reactor and thus is not a re-criticality at all.
- why a one-time injection of Boron would have no long-term effect if it is re-criticality
- levels of gas the same after the injection of boron as before the injection (Nov 1 and Nov 2 measurements)
- questions of how boron may affect the Areva chemicals reaction to decontaminate water
-calculations and measurements CAN be done to determine if it is a re-criticality