March 21st, 2011 – NR Program Questions on NRC BWR MELCOR Spent Fuel Assessment

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Below are questions from NR program on the subject from 1015 call 21 Mar 11-
1. What is the decay heat assumed in the model. How is the fuel and its decay heat distributed radially (temperature plots indicate similar behavior for the “fresh” and “older” fuel). What are the decay heat assumptions for the “recently discharge” and “older discharged” fuel?
2. Clad temperature plots indicate complete clad relocation at about 17.6 days. What is the failure mechanism modeled in MELCOR? (Highest temperature is too low to be melting. All axial elevations regardless of temperature fail at the same time.)
.3. What is the fraction of zircaloy that has oxidized? The hydrogen generation plot shows increase of hydrogen generation due to zircaloy stopping at about 17.6 days (consistent with relocation) and no hydrogen generation after that.
4. What is the nodalization of the MELCOR model?
5. Why did the calculation stop at 18.2 Days?
6. Are there any results available from CAV or CVH Packages?
7. In the model, is the depleted oxygen being replenished from outside the building?
8 ._On the ‘hydrogen generation’ curve, all of the hydrogen generation appears to stop prior to relocation of the core.  What is the reason for the stopping of hydrogen generation?
9. What is the distribution of the older vs newer fuel in the pool and how was it modeled in the analysis? Can NRC contact GE spent fuel personnel to get insight into how Daiichi plants may distribute fuel?
10. Reports – please provide copies of the 5 reports that were given to GE on this analysis. Also, provide a bibliography of the other relevant reports for the BWR spent fuel pool analysis.
Pages From C143073-02B –12 NR Program Questions on NRC BWR MELCOR Spent Fuel Assessment

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