ML20086A088
| ML20086A088 | |
| Person / Time | |
|---|---|
| Site: | Wolf Creek  |
| Issue date: | 11/11/1991 |
| From: | Rhodes F WOLF CREEK NUCLEAR OPERATING CORP. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| ET-91-0212, ET-91-212, IEB-88-011, IEB-88-11, NUDOCS 9111180232 | |
| Download: ML20086A088 (2) | |
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LFCREEK W@ NUCLEAR OPERATING rorrest T. nnooes November 11, 1991 Vice Pronident
. Eng.ncenna a Tecnnicai services ET 91-0212 U. S. Nuclear Regulatory Commission ATTN:
Document Control Desk Mail Station Pl-137 Washington, D. C.
20555
Reference:
Letter dated October 4, 1991, from W. D. Reckley (NRC) to B. D. Withers (WCNOC)
Subject:
Docket No. 50-482:
Response to Request for Additional Information Associated with NRC Bulletin 88-11 Gentlemen The purpose of this letter is to transmit additional information concerning NRC Bulletin 88-11,
" Pressurizer Surge Line Thermal Stratification',
as requested in the Reference.
This includes information required to address the applicability of the Westinghouse owner's Group (WOG) detailed analysis program results to Wolf Creek Generating Station (WCGS) and a summary of the conclusions of the pressurizer nozzle evaluatjun.
As stated in the. Reference, the WOG methodology for evaluation of stress and fatigue effects on the surge line due to thermal stratification and thermal l
striping was found to be acceptable.
Wolf Creek Nuclear Operating Corporation (WCNOC) utilized plant specific data to demonstrate compliance with the requirement of NRC Bulletin 68-11 and Section III of the ASME Code.
-The results of the plant specific analysis for WCNOC indicate that the surge line, nozzle, and supports meet the applicable design code and r
l other USAR and regulatory commitments.
The Attachment p"cVides the' l
requested information.
1
-If you have any questions concerning this matter, please contact me or
-Mr. T. E. Cribbe of my staff.
Ver truly yours, t
Oc-Forrest T. Rhodes i4 Vice President l N" Engineering & Technical Services i
& C' FTR/aem I'
w l. ;$
Attachment MZ cc A. T. Howell (NRC), w/a
[. g R. D. Martin (NRC), w/a
[7 9,
G. A. Pick (NRC), w/a
/
W. D. Reckley (NRC), w/a
/
g P.O Box 411 i Burhngton, KS 66839 ! Phone (316) 364-8831 l
An Equal Opportunity Empeyer M F HC VET
Attachment to ET 91-0212 Pag ( 1 of 1 a
Response to Request for Additional Information for NRC Bulletin 88-11 In a letter dated October 4,
- 1991, from W. D. Reckley,
- NRC, to B. D. Withers, Wolf Creek Nuclear Operating Corporation (WCNOC),
it was conveyed that the Westinghouse owners Group (WOG) detailed analysis program results could be used to satisfy' Actions 1.c and 1.d of NRC Bulletin 88-11, provided that plant specific applicability was demonstrated and additional evaluations not included in the WOG program were performed.
These additional evaluation requirements faciude pipe supports and combined piping loads other than just the thermai stratification and striping loads, to verify that the resultant stresses are in compliance with the requirements of Section III of the ASHE Code.
WCNOC utilized the WOG methodology to perform a plant specific analysis using Wolf Creek Generating Station (WCGS) data.
This analysis included WCGS specific Operating Basis Earthquake (OBE) bending moments, therefore, verification of the applicability of the WOG results is not necessary.
Seismic Operatine Basis Earthauake Bendinn Homents:
WCNOC performed plant specific analysis of the pressurizer surge line piping and nozzles to demonstrate compliance with the requirc.ments of NRC bulletin 88-11.
The primary purpose of this specific analysis was to develop transients applicable to WCGS which include the effects of stratification and. to evaluate these effects on the structural integrity of the surge line.
The transients were developed following the same general approach originally. established and alrer.dy accomplished under programs completed for the WOG.
In this analysis, transients _and seismic OBE bending moments were used based on plant specific data, including modeling the existing piping and supports configuration and utilizing the applicable seismic response spectra.
The surge line displacemente, stresses and support loadings were determined.
The stresses were used to perform a fatigue analysis for the surge line.
The results of the analysis indicate that the requirement of NRC Bulletin 88-11 and Code requirements cre satisfied.
Pressurizer Noz( 33.
The pressurizer nozzle loads from pipe thermal stratification were evaluated according to the requirements -of Section III of the ASME Code.
The evaluation required a simplified elastic-plastic analysis per NB-3228 of the Code which included-the calculations of primary plus secondary stress intensities and the fatigue usage factors.
The results of this analysis identified that the maximum stress intensity without. thermal bending stresses is 18.01 h8A.
compared to the code allowable value of 38.91 kei.
The maximum membrane plus bending stress intensity due to thermal pipe loads only is 17.28 kai compared to the allowable of 38.91 kai.
The maximum fatigue usage is 0.21 compared to the allowable of 1.0.
The analysis concluded that the WCNOC pressurizer nozzle meets the Code stress allowables under the cyclic loading from pipe thermal stratification, and meets the fatigue usage requirements of Section III of the AfME Code.