ML20217C765
| ML20217C765 | |
| Person / Time | |
|---|---|
| Issue date: | 10/09/1997 |
| From: | Shao L NRC OFFICE OF NUCLEAR REGULATORY RESEARCH (RES) |
| To: | Lainas G NRC (Affiliation Not Assigned) |
| Shared Package | |
| ML20217A298 | List: |
| References | |
| REF-GTECI-150, REF-GTECI-NI, RTR-NUREG-0933, RTR-NUREG-933, TASK-150, TASK-OR GL-96-06, GL-96-6, NUDOCS 9804240042 | |
| Download: ML20217C765 (2) | |
Text
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NUCLEAR REGULATORY COMMISSION o
2 WASHINGTON. D.C. 2066H001
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U+9....,o October 9, 1997 HEMORANDUM T0:
Gus C. Lainas, Acting Director Divi ion of Engineering ffic of cle r Rei tor Regulation FROM:
rence C.
- hao, li to Division of Engineering Technology l
l Office of Nuclear Regulatory Research i
SUBJECT:
GENERIC SAFETY ISSUE 150, "0VERPRESSURIZATION OF CONTAINMENT PENETRATIONS' This is in response to your memorandum of September 10, 1997, wherein DE NRR requested that DET, RES review the assumptions and record regarding GSI 150,
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including the evaluation resulting in the prioritization of the GSI in the DROP category.
l GSIs are prioritized in accordance with the Commission approved procedure that l
is documented in NUREG 0933. They are prioritized by developing a quantitative assessment of safety benefits (risk reduction) and NRC and Utility impacts (costs). Based on the extent of potential risk reduction to the public and the impact /value ratio develored from this assessment, and as further adjusted by qualitative judgements, a priority is determined as indicated in NUREG 0933. A priority of HIGH, NEDIUM, LOW, or DROP is assigned. The procedure was not intended fer use to prioritize issues of compliance with existing regulatory requir.Nnts.
It is a simplified Regulatory Analysis used for screening to determine priority for assigning resources for resolving GSIs. RES does not assign resources to resolve GSIs with a LOW or DROP ranking.
Prioritizations of GSIs that are found to be in the LOW or DROP category are sent to NRR for peer review before being published in NUREG 0933. RES records i
indicate that this was done for GSI-150 in 1991.
Procedurally, if GSIs are i
determined to involve compliance with already existing NRC requirements then j
they are forwarded to NRR for disposition.
In addition, in accordance with RES 0.L. 7 GSIs not assigned staff resources for resolution (LOW or DROP) may be reassessed in the future if new information becomes available that could change the original priority.
i RES has reviewed the scope of GSI 150 in the context of the piping described in item (3) of GL 96 06, i.e., " thermally induced overpressurization of isolated water filled piping sections in containment." We have concluded that the over3ressurization of piping within containment penetrations addressed l
within tle scope of GSI 150 is a subset of the third item addressed in the GL.
1 The GL also addresses isolated piping sections that are beyond the scope of GSI 150.
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Lainas 2-RES also has reviewed the GSI 150 prioritization documented in NUREG 0933.
The GSI was prioritized using the prioritization procedure described above.
There is no indication in RES records that a compliance determination was made as a part of the RES prioritization effort or the NRR peer review during the prioritization of GSI-150. Had this been recognized as a compliance issue earlier, it would not have been classified as a GSI. As is normally done when an issue is prioritized, simplifying assumptions about failures, related risks to the public, and costs associated with reducing risk were made.
- Included, as noted in the NRR memorandum, is the assumption of uniform strain of the piping in response to expansion of trapped fluid within the isolated piping.
Issues that were not addressed include the effects of non uniform strain concentrations and compliance with design Code requirements.
Based upon a review of the prioritization of GSI 150 GL 96 06, and discussions concerning ASME Section III, RES concludes that the issue covered in the scope of GSI 150 is a compliance issue. Additionally, we conclude that l
this issue is adequately addressed in GL 96 06.
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R. Wessman l
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