ML20149G231
| ML20149G231 | |
| Person / Time | |
|---|---|
| Site: | Wolf Creek  |
| Issue date: | 02/12/1988 |
| From: | Withers B WOLF CREEK NUCLEAR OPERATING CORP. |
| To: | NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM) |
| References | |
| WM-88-038, WM-88-38, NUDOCS 8802180181 | |
| Download: ML20149G231 (3) | |
Text
,
w of WQ4.F CREEK NUCLEAR OPERATING CORPORATION Bart D. We4rs
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February 12. 1988 VM 88-038 U. S. Nuolear Regulatory Co:nraission ATTN:
Document Control Desk Vashington, D. C.
20555 Subjoet:
Docket No.
50-482:
Response to Request for Additional Information Concerning Main Steam Line Break Superheat Analysis Gentlemen:
The attachment to this letter is being provided as a result of recent discussions with Messrs. T. Alexion, P.
O'Connor and H.
Valker of the NRC Staff, Mr. D. Shafer of Union Electric Company and Mr.
K.
Petersen of Volf Creek Nuclear Operating Corporation (VCN00). WCNOC was requested to provide additional information concerning the SNUPPS main steu line break outside containment with superheat steam release analysis.
If you have any questions concerning this submittal, please contact me or Mr. O. L. Maynard of my staff.
Very truly yours,
_ _ _ - _/
Bart P. Withers President and Chief Executive Officer co B. L. Bartlett (NRC), w/a R. D. Martin (NRC), w/a P. V. O'Connor (NRC), 2 w/a H. Valker (NRC), w/a 6hk h2 5
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f PO. Boa 411/ Durtrgton, KS 66839 / Phone (316) 3644831 g
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Attachment to WM 88-0036 Page 1 of 2 February 12, 1988 Volf Creek Nuolear Operating Corporation Wolf Creek Generating Station Docket No. 50-482 RESPONSE TO NRC QUESTIONS CONCERNING SNUPPS MAIN STRAM LINE BREAK SUPRRHEAT ANALYSIS ITipt 1:
Provide further clarification concerning the commercial grade main steam flow transmitters mentioned in response to Question 1 of letter dated 10/2/87 (Reference 1).
RRSPONSE TO ITEM 1:
In reference 1,
the response to Question 1 noted that non-Class IE main steam line flow transmitters could be used as alternate indication for verifying steam generator isolation.
These transmitters were mentioned because they would provide direct indication of steam flow that could assist the plant operators in verifying isolation valve closure.
However, use of these transmitters is not a requirement because the fully qualified, Class IE indicating circuits mentioned in Reference 1, i.e.,
steam generator level and pressure, auxiliary feedwater flow, and reactor coolant temperature, would themselves provide the necessary information to verify steam generator isolation.
ITEM 2:
Provide clarification concerning the electrical control cable for the one main steam isolation valve (MSIV) at Wolf Creek Generating Station (WCGS) mentioned in response to Question 3 of Reference 1.
RESPONSR TO ITEM 2:
l Table 3.4 transmitted via Reference 2 shows that the qualified tempe rature l
of the affected MSIY control cable is exceeded during the worst case postulated high energy line break with superheat effects.
1 i
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Att:ch:mnt to WM 88-0038 Page 2 of 2 February 12, 1988 The MSIVs are fast acting and close in 5 seconds or less upon receipt of a steam line isolation signal.
The M3IVs are not required to be used again after they' initially elose, and a failure modes and effects analysis has verified that the MSIY will not reopen' as a result of environmentally induced failure of the control cable.-
After the subject valve -is closed, the subsequent _ failure. of the control cable would not mislead plant operators into performing actions adverse to plant safety.
Should the control cable for this one MSIY fail in a mode which would prevent the MSIV from closing during a main steam line break in the steam tunnel, the results would be identical to the assumed rupture of a steam line in the pipe-break-exclusion-area upsteam of an MSIV.
USAR Section 15.1.5 documents the analysis of a double-ended steam line rupture which steam generator to blow down completely.
The remaining for one provides steam generators are still available for the dissipation of decay heat after the initial transient is over. Also, regardless of the break location, no more than one steam generator would experience an uncontrolled blow down even if one of the main steam line isolation valves fail.
In this respect, the subject MSIV satisfies the criteria for a NUREG-0588 Appendix E Category C component for the main steam line break outside containment accident.
line break outside containment with superheat The postulated 'high energy A single affects analysis assumed a break in the break exclusion region.
active failure concurrent with the postulated break was not asrumed which is consistent with NRC position provided in Reference 3.
Therefore, the failure of one MSIY to close due to environmental effects results in one steam generator identical conditions of the uncontrolled blow down of postulated in USAR 15.1.5.
References:
1.
Letter WM 87-0253 dated 10/2/87 from B. D. Vithers, VCNOC, to NRC 2.
Letter WM 87-0107 dated 4/1/87 from B. D. Withers, VCNOC, to NRC 3
NRC Memorandum dated 4/29/85 from H.
Denton, ONRR, to V.
- Stello, DEDROGR, Position on a MSLB in Superpipe Concurrent with a Single Active Pailure l
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