Expert who worked at Sandia Labs: âTEPCO data suggest that fission is ongoingâŚ This is bad newsâ â âTruly scaryâ that nobody in Japan seems to know basics of reactor accident progression
April 21st, 2011
After 5 Halflives, I-131 Higher than Cs-134/137 Suggests Ongoing Criticalities, Gerson Lehrman Group, April 19, 2011:
âŚ Japanese regulators NISA and MEXT seem oblivious of the mysterious fact that I-131 Bq âreactor densityâ is still often reported double the Cs-134/137 Bq. The TEPCO data suggest that fission is ongoing despite the reactor shutdowns. This is bad news. âŚ
Everyone with just a very basic understanding of reactor safety should know that once a reactor is scrammed, U-235 is no longer fissioning, and I-131 has no parent which can be decaying to create it in an ongoing processâŚ the water circulating in intact SNF pools should have absolutely no detectable I-131 in them. âŚ
[I]t has been almost five full 8-day halflives for their I-131 to decay to stable xenon. At t=0, as we say, the Bq of I-131 and Cs-134 and Cs-137 would all be approximately equal, but, after five I-131 halflives, the âreactor densityâ radioactivity of I-131 should be only 1/2**5=~3% of what it was originally. Go look at all the data of relative radioactivity that TEPCO is reporting with dates of April 19, 2011 and youâll see that instead of I-131 being below the levels of the two cesiums, I-131 is often twice as high as the two cesiums always reported.
The fact that nobody in Japan seems to know basics of reactor accident progression that I learned at Sandia Labs in early 1980s is truly scary, because it suggests they are playing with these broken/leaking reactors and SNF pools inside at least three buildings totally destroyed by steam explosions âŚ as if the reactors and their SNF pools are broken toys that theyâre using trial and error to try fixing.