APR: your source for nuclear news and analysis since April 16, 2010

Thursday, November 3, 2011

Xenon / Fukushima Daiichi No. 2 - Thursday afternoon update

The information at present from TEPCO echoes that printed here this morning. Here is the latest TEPCO analysis:

-We found a possibility to detect short-half-life radionuclide such as Xe-
133 and Xe-135 according to our radionuclide analysis sampled on November
1 by the gas management system of the reactor containment vessel. We
continued to monitor the temperature, pressure and data from monitoring
post and there was no significant fluctuation from those data. As we
can't deny a possibility of fission reactions, we decided to start
injecting boric acid water from reactor feed water system at 2:48 am on
November 2 and stopped it at 3:47 pm on the same day. At around 7:20 pm
on the same day, Japan Atomic Energy Agency evaluated that the TEPCO's
analysis result of the short-half-life radionuclide such as Xe-133 and
Xe-135 detection was valid. We consider that they were generated by the
spontaneous fission on the grounds that the concentration of detected
short-half-like radionuclide (Xe-135) is low, that short-half-like
radionuclide (Xe-135) was detected even after the boric acid, which stops
nuclear fission chain reactions, was injected, and that the parameters of
the reactor were not significantly changed.

(Bold text above highlighted by APR for clarity.)

TEPCO representatives are making, apparently, the same statements to all media outlets but are seemingly at this point not making any differentiation between spontaneous fissions of U-235 and the two Curium isotopes mentioned this morning.

Also at Unit 2... TEPCO has noted a slight increase in hydrogen concentration in the PCV at this plant. A reading of 2.7% on October 30 compares now with a reading of 2.9% on November 3rd. Because of this, TEPCO has increased the volumetric flow rate of nitrogen injection from 21 m³/hr to 26 m³/hr.

More details when available... but for now the situation is completely stable and (as I've said before) no fission chain reaction is occurring at No. 2 plant - and neither is a continued meltdown.

2:24 PM Eastern Thursday November 3, 2011


  1. Will, can you speculate in (jittery/alarmed) layman terms just how much of this substance in weight or volume are we talking about being found here? Thanks.

    James Greenidge

  2. @jimwg: I can't speculate on a total amount being generated because, while I know what the percentage of the sample volume was, I don't know what the actual sample total volume was -- nor do we have an exact handle on the generation rate yet. This will probably be figured by NISA, JAEC or TEPCO or a consortium of these and be published.

  3. @jimwg: One thing for sure is that it is not tons and tons of the stuff. It's a tiny fraction of the total gas in the PCV.