April 1st, 2011 – MELCORE source term for use towards Tokyo

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From:Hoc, PMT12
Sent:Friday, April 01, 2011 4:17 AM
To: Miller, Marie
Cc: Casto, Chuck; Monninger, John; Collins, Elmo; FOIA Response.hoc Resource
Subject: FW: Request for Copy of Source Term Sent to NARAC
Attachments: MELCORE Source term for use towards Tokyo

Here it is. RASCAL was not used…this was developed by RES.

From: Miller, Marie
Sent: Friday, April 01, 2011 4:55 AM
To: Hoc, PMT12
Subject: Request for Copy of Source Term Sent to NARAC

When I reported out to Chuck et al that you had provided a source term to NARAC, he and John Moninger requested a copy of the RASCAL runs to get a idea of the source term. Can you please send a copy of the RASCAL to me for our use here. You may also want to copy John M. Chuck C and Elmo C.

Quayle, Lisa

From: PMT09 Hoc
Sent: Thursday, March 31, 2011 9:12 PM
To: [email protected]
Cc: Hoc, PMT12
Subject: MELCORE Source term for use towards Tokyo
Attachments: oledata.mso

Mr. Hoglin,

The following information is provided by RES in response to a PMT request of 3/30/11 to provide a realistic, up-to-date estimation of source terms for dose projections to address future potential radiological releases from the Fukushima Unit 1 reactor and the Unit 4 spent fuel pool. The source terms herein provided are based on MELCOR analyses that have been performed for a similar but not identical severe accident event for a BWR Mark I reactor and spent fuel pool. The spent fuel pool analysis did consider the Fukushima Unit 4 spent fuel pool decay heat and water volume. The reactor analyses results and radiological releases attached reflect the Fukushima Unit 1 reactor core inventories adjusted for decay since the time of the accident until April 15, 2011 (as requested by the PMT).

The premise of the calculation based on discussions with the PMT, as we understand the background, is that a hypothetical event may potentially occur at the Unit 1 reactor requiring abandonment for some 24 hours, during which water injection to the Unit 1 reactor and Unit 4 spent fuel pool is interrupted (ceased). The question then is posed, “What would the radiological release be for the next 24 hours?” After 24 hrs, injection is assumed to be resumed.

For the reactor analysis, we have conservatively assumed that core damage begins promptly; the radiological release begins at the start of the 24 hour period. We have also assumed that the initial heat up (on or about March 11 th and 12th, 2011) of the Unit 1 reactor core already resulted in severe damage to 70% of the core. Certain radionuclides have already been scrubbed in the suppression pool and are no longer available for the
release. The attached table provides the detailed radiological release. For the spent fuel pool, recent information from the RST (3/31/11) indicates that the Unit 4 spent fuel pool has sufficient level to maintain the spent fuel in the pool to remain covered for approximately 5 days at saturated conditions (-100 C). Our analyses indicate that neglect of the pool for 24 hours will not lower the water level sufficiently to cause any significant heat up of the spent fuel in the pool. This estimate has large available margins. Therefore, we recommend that no spent fuel pool radiological release be assumed for the event being considered.

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