ML20198A181
| ML20198A181 | |
| Person / Time | |
|---|---|
| Site: | Wolf Creek  |
| Issue date: | 12/10/1998 |
| From: | Muench R WOLF CREEK NUCLEAR OPERATING CORP. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| ET-98-0099, ET-98-99, GL-96-06, GL-96-6, NUDOCS 9812160172 | |
| Download: ML20198A181 (4) | |
Text
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.o WSLF CREEK NUCLEAR OPERATING CORPORATION Richard A. Muench
. Vice President Engineering DEC 101998 ET 98-0099 U. S. Nuclear Regulatory Commission ATTN:
Document Control Desk Mail Station P1-137 Washington, D.
C.
20555
Subject:
Docket No. 50-482:
Relief Request to Allow Use of ASME Code i
Case N-611, "Use of Stress Limits as an Alternate to Pressure Limits;Section III, Division 1, Subsection NC/ND-3500" l
Gentlemen:
Pursuant to the provisions of 10 CFR 50.55a (a) (3) (1), Wolf Creek Nuclear Operating Corporation (WCNOC) requests approval for use_ of ASME Section III Code Case N-611, "Use of Stress Limits as an Alternate to Pressure Limits; Section' III, Division - 1, Subsection NC/ND-3500," at Wolf Creek Generating Station to assist in the resolution of' Generic Letter 96-06, " Assurance of Equipment Operability and Containment Integrity Dur ing Design-Basis Accident Conditions." This request is limited to use of Code Case N-6]l for resolution of Generic Letter 96-06 issues.
Code Case N-611 was approwd by the Amar icaa Society of Mechanical Engineers ( ASME') Board on Nuclear Codes and Standards by Letter Ballot 695 on July 30, 1998.
It is planned to be published in Supplement 2 to the 1998 Bo11er and Pressure Vessel Committee Nuclear Code Case Book in' December of 1998.
Background
Wolf Creek Nuclear Operating Corporation is evaluating piping conditions inside containment under the conditions postulated in Generic Letter 96-06.
For those postulated conditions, it is assumed that isolation valves inside and outside containment are closed or caused to close, trapping water between the isolation valves.
Functionality (i.e.,
ability to change valve position) of these valves is not required once the valves move to their closed position.
However, pressure integrity is required.
During some design-basis accidents, the temperature inside containment will rise, causing component stresses to rise due to the. thermal expansion of the trapped water.
WCNOC has evaluated these conditions and feels it is appropriate to request the use of ASME Code
}
Case N-611.
I Basis for Use ' of Alternative to Subsection NC/ND-3521 and Table NC/ND-3521-1
/
WCNOC has performed detailed stress analyses for the applicable design-basis accidents and found that the Code allowable stress limits are not exceeded for any conditions under the postulated loads.
Howaver, Subsection NC/ND-3521 (b) for valves associated with the postulated conditions, That is, even though
' [\\ '
, gnd T @ e NC/ND-3521-1 specify a factored pressure limit (Pmax) in addition to 7
3 tthe+ 1dcMitified. stress limits. Analysis shows that this Pmax could be exceeded Code stress limits are met, the tabulated allowable pressure could be exceeded.
When this condition was explained to the ASME Code Committee, the Committee concluded that the Code should allow Pmax to be exceeded if it could be shown that the allowable stress limits were anet.
Consequently, Code Case 4 PQ_How 411 / Rurhngton, KS 66839 / Phone: (316) 364-8831 9812160172 981210 al Opp dunny Empoye M FHC VET f
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'ET 98-0099 Page 2 of 2 i
N-611 was witten and approved by the ASME Committee.
ASME Code Committee i
members have indicated that the Code will be revised to incorporate the provisions of Code Case N-611.
I
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Using the provisions of Code Case N-611 will allow WCNOC to demonstrate that j
ASME Code provisions have been complied with for all Generic Letter 96-06 l=
' concerns.
Analysis. demonstrates that the Code allowable stresses are not exceeded for any case under the postulated conditions.
Therefore, WCNOC considers that the use of Code Case N-611 will provide an acceptable level of quality and safety, and is a reasonable alternative to the requirements ' of ASME Section III.
)
A draft copy of Code Case N-611, as approved by the ASME Board' is providnd in
- Attachment 1.
Since Code Case N-611 has just recently been approved, it is not included in the most recent listing of NRC approved Code Cases in l
" Design and Fabrication Code Case Applicability,Section III, Division I." provides a summary of commitments made in this letter.
~~ Approval.for use of Code Case N-611 is requested by March 1, 1999, to support l
the completion of WCNOC Generic. Letter 96-06 evaluations.
.If you have any questions concerning this response, please contact me at (316) l 364-4034, or.Mr. Michael J. Angus at (316) 364-4077.
Very truly yours,
?
5 Richar A. Muench RAM /dle Attachments cc:
W.
D. Johnson (NRC), w/a E.
W. Merschoff (NRC), w/a K. M. Thomas (NRC), w/a Senior Resident Inspector (NRC), w/a l
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. to ET 98-0099 Page 1 of 1 ITEMhh'h CAST h!-xxxxx CASES OF ASME BOILER AND PRESSURE VESSEL CODE Case X$fdDe Use of Stress Limits as an Alternate to Pressure LimitsSection III, Division 1, Subsection NC/ND-3500 Inquiry: What alternative rules may be used to the factored pressure limit Pmax in valve design, as outlined in NC/ND-3521 (b) and Table NC/ND-3521 17 Reply: It is the opinion of the Committee that the factored pressure linut, Pmax as required in NC/ND-3521 (b) and Table NC/ND-3521-1 need not be met. provided the stress limits of Table NC/ND-3521 1 are met.
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.- to ET 98-0099 Page 1 of 1 LIST OF COMMITMENTS The fdllowing table identifies those actions committed to by Wolf Creek Nuclear Operating Corporation (WCNOC) in this document.
Any other statements in this submittal are provided for information purposes and are not considered to be commitments.
Please direct questions regarding these commitments to Mr.
Michael J.
Angus, Manager Licensing and Corrective Action at Wolf Creek Generating Station, (316) 364-4077.
COtNITMENT Due Date/ Event
]
NONE N/A l
9 e