March 24th, 2011 – New information from AEC casts doubt on GE’s analysis of venting and hydrogen explosions at Fukushima Daiichi

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From: Kelly, John E (NE)
Sent: Fri Mar 25 00:10:21 2011
Subject: FW: Hydrogen

Here is new information from the Japan AEC. I know GE thought that the vented via a wetwell line, but this is a different interpretation. This scenario means that the head bolts stretched, which GE didn’t think was what happened. I will need the pressure histories for the first multiple hours of the situation (especially In the containment) in order to provide a response. Have we plotted that info yet?

From: Akiraomoto [mailto:l b)(6) –
Sent: Thursday, March 24, 2011 11:46 PM
To: Kelly, John E (NE)
Cc: Lyons, Peter; [email protected]; Binkley, Steve; SCHU; Poneman, Daniel; Connery, Joyce; [email protected]
Subject: Re: Hydrogen

Dear Mr. John Kelly,
Akira OMOTO, a Commissioner in the AEC is writing to you.

Thank you for sending your note.

I thought that the following points need to be considered;

1) SAM (Severe Accident Management) procedure and modifications were finished in the 90’s including containemnt “hardened” scrubbing venting to the main stack (NYT article is wrong) via wetwell air space, makeupo water using fire protection system from large size portable water storage tank, bus inter-connection to other units (this worked very well in unit 5 and 6 since one EDG continued operation), and others.

2) All the three units (IF] -3) experienced containment overpressure in the early phase of the accident, which caused excessive leakage from flange, ailocks and other peentrations. Hydrogen produced by Metal Water reaction in the core damage process must have escaped to the reactor building via this containment leakage path and accumulated on the top and caused deflagration/detonation there. Further, containment was steam inerted and a large fraction of hydrogen escaped -by “hardened” venting.

3) Still radiolysis of water is ongoing and produces hydrogen/oxygen in the containment (hopefilly in the RPV). thus, still the risk of hydrogen deflagration/detonation exists, in my view.
Remeber that if lodene and other Halogen elements exist in the water they function to retard or prevent recombination of hydrogen/oxygen.
My paper on hydrogen control in BWR (Nuclear engineering and Design, 2000) discussed this point.

Study is ongoing in TEPCO;
a) to open vent valve of RPV while keeping steam inert conditionm and
b) to send nitrogen or other inert gas to the containment. However, to inject nitrogen containment isolation must be unlocked first and then valve operation must be done in an extremely harsh environment.

akira OMOTO


AEC Hydrogen Analysis – Pages From C142015-02B
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