ML20196G055
| ML20196G055 | |
| Person / Time | |
|---|---|
| Issue date: | 10/03/1977 |
| From: | Minogue R NRC OFFICE OF STANDARDS DEVELOPMENT |
| To: | Case E Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML20196F442 | List:
|
| References | |
| FOIA-87-854 NUDOCS 8803040340 | |
| Download: ML20196G055 (2) | |
Text
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' loob FCR: Edson G. Case, Acting Director Offica of Nucin t Reactor Regulation 004
- 377 FIOM:
Robert B. Minogue, Director Office of Standards Development
SUBJECT:
SYSTENATIC EVAWATION PIOGRAM (SEP) i r
I his is in response to your memorandum dated August 19, 1977, as it applies the SEP to Spent Fuel Cask Drop Accidents ('Ibpic XV-24). n e evaluation 3
identified includes potential for cask drops, resulting damage to fuel inside the cask aM to structures outside of the cask, aM the radiological l'
L consequences of that damage. Two areas inplied but not explicitly covered i
are: 1) damage to radiation sources outside of the cask resultirq fra a cask drop and the radiological consequences of that damage; and 2) the non-radiological consequences of damages to the facility resulting frcm a cask l
decp. Evaluation of all of these aspects woild appear to provide cmplete coverage of the subject.
With respect to the potential for cask drops, we understand your staff evaluates the reliability of the crane used for cask lifting, including the j
cables and the crane hook. To fully evaluate the drop potential, however, the assessment should include all devices below the crane hook, includity a strongback, if used, and the lifting lugs which are a structural part of
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the cask. Presently, the lifting lugs are evaluated by the Transportation Branch, NMSS in its package review, in accordance with the standards of 10 CFR 71.31 (c). Current plans are to retain in Part 71 only the lifting L
lug requirement that "failure of the device un3er excessive load would not impair the containment and shielding properties of the cask". Plans are
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' to delete the minimum strength requirements for lifting lugs in favor of an overall lifting system review by your staff. W e proposed rule to y
accomplish this deletion is expected in early 1978.
'li Standard Review Plan Section 15.7.5 "Spent Fuel Cask Drop Accidants" appears to be predominantly concerned with the radiological consequences
- of a cask drop fra a height exceeding the regulatory test requirements (10 CFR Part 71) of 30 feet, considering damge to the cask, dan 3e to the fuel and release of the radioactive contents of the cask.
For purposes of evaluating the radiological consequences, Section 15.7.5 appears to assume that any cask dropped from a height exceeding 30 feet
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will fail.
In our view, that assunption is unnecessarily conservative.
i We believe it is necessary and possible to refine that assumption by l
estimting whether a cask is likely to fail as a result of an accidental drop considering specific heights at which the cask is to be handled and specific surfaces within the particular facility onto which the cask could be dropped. %e Transportation Branch, FCES, NMSS, has done analyses of consequences of cask drop accidents and might be of assistance in refinirs such evaluations.
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we understand the NRR review will also consider the damages, including l
radiological consequences, that would result fran dropping the fuel I
elernent cask, during handling within the plant, from any height.
We vrderstand this includes droppire the cask on other radioactive source j
material, such as an irradiated fuel storage basin, although there is I
no guidance yet available.
In sumury, we believe your menorandum dated August 19, 1977, adequately defines nest of the considerations for evaluating spent fuel cask drop accidents, but sugest consideration be given to the effect on outside sources and non-radiolcgical consequences of such accidents. We also sugest further coordination arrong our staffs and tNS in implementity the evaluations.
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g obert B. Minogue, Director R
Office of Standards Development 1