ML17326B552
| ML17326B552 | |
| Person / Time | |
|---|---|
| Site: | Cook  |
| Issue date: | 03/06/1989 |
| From: | Alexich M INDIANA MICHIGAN POWER CO. (FORMERLY INDIANA & MICHIG |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| AEP:NRC:1086, IEB-88-011, IEB-88-11, NUDOCS 8903140427 | |
| Download: ML17326B552 (6) | |
Text
gcc<LEP<TED DlRIBUTION DEMONS~ON SY) TEN REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)
DOCKET 05000315 05000316
SUBJECT:
Responds to NRC Bulletin 88-011, "Pressurizer Surge Line Thermal Stratification. "
DISTRIBUTION CODE:
IE11D COPIES RECEIVED:LTR ENCL SIZE:
TITLE: Bulletin Response (50 DKT)
NOTES ACCESSION NBR:8903140427 DOC.DATE: 89/03/06 NOTARIZED: YES FACIL:50-315 Donald C.
Cook Nuclear Power Plant, Unit 1, Indiana 50-316 Donald C.
Cook Nuclear Power Plant, Unit 2, Indiana AUTH.NAME AUTHOR AFFILIATION ALEXICH,M.P.
(formerly Indiana
& Michigan Ele RECIP.NAME RECIPIENT AFFILIATION Document Control Branch (Document Control Desk)
RECIPIENT ID CODE/NAME PD3-1 LA STANG,J INTERNAL'EOD/DOA NRR/DEST/ADE 8H NRR/DEST/MEB 9H NRR/DOEA/GCB 11 NRR/PMAS ILRB12 RGN3 FILE 01 EXTERNAL: LPDR NSIC COPIES LTTR ENCL 1
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/NDIANA NICHIGAM PlhfER AEP:NRC:1086 Donald C.
Cook Nuclear Plant Units 1 and 2
Docket Nos.
50-315 and 50-316 License Nos.
DPR-58 and DPR-74 ALTERNATIVE SCHEDULE FOR EVALUATION OF PRESSURIZER SURGE LINE THERMAL STRATIFICATION U.
S. Nuclear Regulatory Commi sion Attn:
Document Control Desk Washington, D.C.
20555 March 6, 1989 Dear Dr. Murley; On December 20,
- 1988, the NRC issued Bulletin No. 88-11 "Pressurizer Surge Line Thermal Stratification." It requests all addressees to establish and implement a program to confirm pressurizer surge line integrity in view of the occurrence of thermal stratification, and requires them to inform the staff of the actions taken to resolve this issue.
Pursuant to satisfying the requirements and schedules of Bulletin 88-11, Donald C.
Cook Nuclear Plant is participating in a program for partial resolution of this issue through the 'Westinghouse Owner's Group (WOG).
The WOG program was approved at the October 1988 meeting and has the following objectives:
o Develop a generic Justification for Continued Operation (JCO) to assure that plant safety is not compromised while the effects of thermal stratification are being determined.
o Collect and summarize relevant design, operational, analytical, and test data for as many WOG plants as possible.
In addition, a representative sampling of approximately ten plants will be selected to perform a review of plant records and conduct interviews with.
operations personnel.
o Evaluate data and identify and prioritize significant parameters contributing to this issue.
Categorize (group) plants based on these parameters.
Dr. T.
E. Murley AEP:NRC:1086 o
Recommend additional monitoring to supplement the existing transient database required to bound all WOG plants.
o Estimate the effect of thermal stratification on fatigue life as a function of key parameters.
o Recommend short term and long term actions The WOG program is designed to benefit from the experience gained in the performance of several plant specific analyses on Westinghouse PWR surge lines.
These detailed analyses included definition of revised thermal transients (including stratification) and evaluations of pipe stress, fatigue usage
- factor, thermal striping, fatigue crack growth, leak before-break, and support loads.
The overall analytical approach used in all of these analyses has been consistent.
and has been reviewed, in
- detail, by the NRC staff.
A significant amount of surge line thermal monitoring data has been obtained in support of these plant specific analyses.
Additional surge line thermal monitoring and plant system data continues to be made available within the WOG, resulting in a steadily increasing database.
A significant amount of progress has been accomplished toward meeting these objectives.
To date, the WOG has completed approximately 80$ of the effort of assembling plant specific design information on all domestic Westinghouse PWRs (55 units total.)
This effort will establish the range of key design parameters and permit grouping of plants based on these parameters.
Based on the information assembled to date, and the experience gained in plant specific analyses and monitoring programs, the WOG evaluation has resulted in the following observations regarding plant similarity and thermal stratification:
0 1.
Thermal stratification (greater than 100 F) has been measured on all surge lines for which monitoring has been performed and which have been reviewed by the WOG to date.
2.
The amount of stratification measured and its variation with time (cycling) varies.
This variation has been conservatively enveloped and applicability demonstrated for plant specific analyses.
Additional monitoring data representing a wider range of surge line configurations may be needed in order to demonstrate the applicability of these thermal stratification transients to other Westinghouse units.
Dr. T.
E. Murley AEP:NRC:1086 3.
Significant factors which can influence the structural effects of stratification are:
a.
Location and design of rigid supports and restraints b.
Pipe layout geometry and size c.
Type and location of piping components 4.
Although the material and fabrication techniques for Westinghouse surge lines are reasonably consistent and of high quality, the design parameters listed in item 3 vary among Westinghouse PWRs.
This variation in design is primarily a result of plant specific routing requirements.
This variability is currently being examined in order to assess the feasibility of a bounding analysis approach.
These observations developed through the on-going WOG program, indicate that the development of thermal stratification loadings and the evaluation of fatigue, considering these
- loadings, is a
complex process.
Therefore, in order to precisely evaluate stratification, additional time is needed.
While more time is needed to evaluate the stratification issue in
- detail, the NDE inspection history at Cook Nuclear Plant, as well as all.other domestic Westinghouse designed PWR's, has not revealed any service induced degradation in the surge line piping that has been attributed to thermal stratification.
In addition, all the plant specific analyses performed to date that have included the loadings due to stratification and striping have validated the "leak-before-break" concept and have substantiated a 40-year plant life.
- Thus, a prudent approach for providing a detailed evaluation of the effects of surge line stratification would be to follow the WOG program grouping evaluation recommendations and monitor as determined to be appropriate.
The WOG expects to complete a grouping evaluation, for the purpose of recommending a list of additional plants where thermal monitoring is needed in the first week of March 1989.
The time required for this additional monitoring will be dependent on plant outage schedules.
To assure that the plant safety is not compromised within the requested period of schedule extension, a JCO will be submitted to the staff.
The JCO which is currently being developed by Westinghouse Electric Corporation, will be submitted by Indiana Michigan Power Company (I&M) to the staff by May 4, 1989.
The JCO will utilize the information, experience, and monitoring data
Dr. T.
E. Murley AEP:NRC:1086 obtained through the WOG program, and will support the alternate schedule discussed herein.
I&M hereby requests an alternate schedule to that requested in Bulletin 88-11.
A schedule of two years, from receipt of the Bulletin, is considered sufficient time to obtain the necessary additional monitoring data, define thermal transients, perform all required analyses and update the stress and fatigue analyses to ensure compliance with applicable code and regulatory requirements.
This schedule, though different from that requested in action l.b of Bulletin 88-11, is consistent with the requirement to update the stress and fatigue analyses within two years as stated in action l.d of the Bulletin.
As previously
- stated, the JCO that is currently being developed, will be submitted by Cook Nuclear Plant to the staff by May 4, 1989.
At, this time, I&M's request for an alternate schedule applies only to item l.b of NRC Bulletin 88-11.
I&M intends to comply with all other requirements of the Bulletin.
This letter is being submitted pursuant to 10 CFR 50.54 (f) and as such an oath of affirmation is attached.
Sincerely, M.
. Ale'xich Ulcc President MPA/eh Attachment cc:
D.
H. Williams, Jr.
W.
G. Smith, Jr.
- Bridgman R.
C. Callen G. Charnoff G.
Bruchmann A. B. Davis
- Region III NRC Resident Inspector
- Bridgman
COUNTY OF FRANKLIN Milton P. Alexich, being duly sworn, deposes and says that he is the Vice President of licensee Indiana Michigan Power
- Company, that he has read the forgoing Response to AEP:NRC:1086
- Bulletin 88-11:
Pressurizer Surge Line Thermal Stratification and knows the contents thereof; and that said contents are true to the best of his knowledge and belief.
Subscribed and sw rn to before me this day ot 7~
198
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NOTARY PU C
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