Wednesday early afternoon update

No important changes in plant parameters to note, except the continued slow cooldown of No. 1 reactor plant concurrent with a slow pressure vessel pressure reading increase (both channels.)

According to NISA, TEPCO intended to begin nitrogen inertion of the containment of No. 1 plant about 1 AM Tokyo time, which would have been 12 Noon Eastern time here. We noted this morning that this was a prudent step that should be taken soon and apparently the owner-operator and oversight groups felt the same way. No official word on similar plans for the other two reactor plants although NISA spokesman Hidehiko Nishiyama is quoted as having said that he expects it. According to Nishiyama the concern at No. 1 plant is due to a suspicion that radiolytic hydrogen has built up .. not metal-water generated hydrogen.

1:45 PM Eastern Wednesday 4/6
ATOMIC POWER REVIEW

UPDATE 3:45 PM Eastern... TEPCO has reported that the actual nitrogen injection didn't begin until about half past one in the morning, Tokyo time or about 12:30 PM Eastern. Work to prepare for it began several hours before. TEPCO warns that this may lead to some radioactive gas releases. Item: If the control rods have been damaged and any B4C has been exposed to steam then methane gas may also be formed. This is much less dangerous than hydrogen, however.