ML20236X026
| ML20236X026 | |
| Person / Time | |
|---|---|
| Issue date: | 09/16/1996 |
| From: | Persinko A NRC |
| To: | Au M, Jensen E NRC |
| Shared Package | |
| ML20236W816 | List:
|
| References | |
| FRN-63FR31364, RULE-PR-72 AF80-1-005, AF80-1-5, NUDOCS 9808070062 | |
| Download: ML20236X026 (1) | |
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From: Andrew Persinko AF86-I To: TWD2.TWP9.MLA, WNP2.ENJ i Date: 9/16/96 11:23am ]f l
Subject:
More info re 72.124 (b)
Additional info on 72.12 A (b) , use of neutron absorbing material:
- 1. The wording in the current 72.124 (b) was in the original rule back in 1980. The original rule applied to both wet and dry storage BUT it seems to have been written more with wet storage in mind.
- 2. I have not found it in any official document but it is felt that the l positive means for assuring continued efficacy was geared toward boraflex l material in spent fuel pools. In a month or so, I should have more info on the problems assocaited with boraflex material in pools---LLNL is doing a study of this.
l 3. I hve not found an official document saying this but I believe that the I borated material is only needed when loading or unloading when the moderator
! is present and that the fuel can't go critiacal when being stored in a dry environment.
- 4. The Standard Review Plan for Dry Cask Storage Systems (NUREG - 1536) that was published in Feb 1996 states that : (a) criticality safety does not rely on" use of more than 75 percent credit for fixed neutron absorbers, unless l
comprehensive fabrication tests capable of verifying the presence and l uniformity of the neutron absorber are implemented" ; and (b) continued efficacy, as used in the rule, can be demonstrated by requiring acceptance i testing of the poisons during fabrication, by showing that the small neutron flux from spontaneous fission and suberitical multiplication results in a negligible depletion of poison material over the storage period, and by assessing the structural integrity and potential for material degradation during storage. If continued efficacy can be demonstrated by design and material properties, then a surveillance or monitoring program to verify continued efficacy of solid neutron absorbers may not be necessary."
We want to clarify the rule to agree with the above. The revised rule should not restate the above since the above is SRP criteria and not regulation.
However, the rule should be more general, as is normally done-- a general rule with specific SRP criteria. I think that if the rule is changed to delete the words " positive means to verify" and change the word " provide" to
" demonstrate", it would agree with the above. Continued efficacy over the life would have to be demonstrated, but that could be done as described above.
This would achieve the goal of assuring the efficacy of the neutron absorbing material without having to enter the canister periodically to test. This revision only applies to dry storge systems and NOT to wet storage systems.
The old rule would still apply to wet storage systems. The words in the revised rule would have to accommodate these two cases.
NMSS/SFPO will await your first cut at providing the actual words. I do not know at what otage of the rulemaking process this occurs. Must the actual words be included in the rulemaking plan or does this occur later since the rulemaking plan is a plan, not the actual revised rule?? I believe that this should complete the info you needed to proceed -- if more is needed, let me know..
CC: TWD2.TWP9.RCA, EXE, SFS,FIY t
9900070062 980004 PDR PR 72 63FR31364 PDR (l[c / (: ic10 6 :