ML20235Z017

Advises of Alternate Schedule for Investigations & Analyses in Response to NRC Bulletin 88-011, Pressurizer Surge Line Thermal Stratification, on Behalf of Owners Group Members. Thermal Striping Evaluation Will Be Submitted by 891031

ML20235Z017
Person / Time
Site:	Rancho Seco
Issue date:	02/24/1989
From:	Spond D BABCOCK & WILCOX OPERATING PLANTS OWNERS GROUP
To:	Rossi C Office of Nuclear Reactor Regulation
Shared Package
ML20235Z010	List: ML20235Z007 ML20235Z017
References
IEB-88-011, IEB-88-11, OG-415, NUDOCS 8903150039
Download: ML20235Z017 (4)

Text

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s* ' OWNERS GROUP LCl

% % c- i. . : ** * - c== -v o.a e wg  % l E IIE Sahmst d er a Working Together to Econornically Provide Reliable and Safe Electrical Power Suite 525 e 1700 Rockville Pike e Rockville, MD 20852 * (301) 230-2100 February 24, 1989 OG-415 Mr. Charles E. Rossi 4 Division of Operational Events Assessment g Office of Reactor Regulation =

U.S. Nuclear Regulatory Commission Washington, DC 20555

Subject:

NRC Bulletin 88-11, " Pressurizer Surge Line Thermal Stratification"

Dear Mr. Rossi:

The subject bulletin requires investigation and analysis of the effects of thermally stratified water in pressurizer surge lines.

Actions to address Paragraph 1.b of this bulletin are required within four months after bulletin receipt with written confirma-l tion of these actions within 30 days. The Bulletin requested those licensees whose investigations and analyses would take more than four months to advise the Staff of their alternate schedule with a justification for the extension. The purpose of this letter is to submit, on behalf of the members of the Babcock &

Wilcox owners Group, such an advisement.

During a September 29, 1988 meeting with members of the NRC staff, the B&W Owners Group described its plans and schedules for addressing the issue of pressurizer surge line thermal stratifi-cation. At that time, the emphasis of the B&W owners Group program was on the collection of generic data, from the Oconee Unit 1 pressurizer surge line. The program has been expanded to include displacement monitors, and the effects of thermal striping. The thermal striping investigations, however, may not be completed within the requested four-month period allotted for the bounding analysis requested in Paragraph 1.b of the subject bulletin.

The immediate emphasis of the B&W Owners Group program is to support the required justification for continued operation by demonstrating that there is no near-term concern over the 8903150039 890306 ,,

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c. . t, integrity of the pressurizer surge line. This program consists of the following:activitiest  !

1. Bounding analysis of piping flexibility .using . data -i derived .- from a' large B&W plant in Germany with plant. l operational and configuration comparisons.

4kRV A comparison of the owners Group plants u has shown the configurations of all plants- with exception of Davis- 1 Besse Unit 1 to be similar. As a result, two sets of '!

analyses are planned; one for Davis-Besse and one for the remaining plants. The operational comparison is not.

yet complete.

The B&W Ovners Group has performed initial bounding I analyses which: are considered conservative based upon '

data derived from a previously instrumented pressurizer

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surge line in Muelhein-Kaarlich, a larger. B&W plant in Germany. This larger plant differs in respect to the surg 4 line layout, diameter and thickness. Therefore the conservatism of the application of the data in' the bounding analyses to the smaller B&W units in the United States requires confirmation.

Evaluations of' stress and fatigue- based upon the preliminary bounding analyses results show the expected life of the surge line to extend beyond the next two years in all cases. Additional details regarding these analyses will be provided by the members of the B&W Owners Group in their Bulletin 88-11 submittals upon completion of the analysis review in accordance with the required schedule.

2. Data collection on a typical B&W plant in the United States (Oconee Unit 1).

An extensive data collection program has been undertaken at Oconee Unit 1 to provide the detailed understanding of the thermal stratification phenomenon to support analyses for all the B&W Owners Group plants. Oconee-1 has now completed its startup and is at full power.

Information from the plant heatup is being evaluated, and data collection is, continuing.

The additional information being supplied from the i Oconoe-1 instrumentation wil rovide both plant-specific information and an impr ed understanding of the stratification phenomenon. The initial bounding analyses results are considered conservative since the temperature differences and the resultant surge line

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' deflections observed' during thel'Oconee-1 heatup are smaller than. predicted in.the analyses..

3. Data evaluation and analysis.'

Demonstration that'.the pressurizer' surge line fully-meets the - applicable - design codes and other' regulatory commitments for the . licensed life.of:the plant, based !

.upon applicable plant specific or - referenced : data, 'is being ' addressed =in the longer ' term in accordance 'with -

the request of the Bulletin paragraph.1.d.

a 4. . Thermal' striping evaluations.

The B&W L owners. Group program includes a review 1of' the

' thermal. striping phenomenon and its! potential impact' upon surge line integrity.

-following elements:

This review contains ' the A.,

A review of the available research data on thermal striping, . including z that produced by the Argonne .

National Lab for the LMTBR sponsored by the-DOE.

B. A thorough examination of the Oconoa' test data 1' for indications of striping. While conclusions have not '

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yet been . reached on. the extent to-which the data =

collected at.Ocones will'be useful toward'this end, the test' program has been oriented to the extent practical to maximize the data-' collection system's capability to detect thermal . variations - associated -

with striping.

C. ,An evaluation of. the striping stress and fatigue effects based ' upon analysis of site and laboratory data.

The striping investigation is expected to extend beyond the requested bulletin response date for Paragraph 1.b. The B&W.

Owners Group will submit the thermal striping evaluation by 1 October 31, 1989.

Very truly yours,

%: L %d D. F. Spond, Chairman B&WOG Materials Committee Arkansas Power i Light Co.

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bcc s ' Materials Committee Steerina Committee M. C. Snow -

AP&L D. H. Williams -

AP&L l M. A. Haghi -

DPCo N. A. Rutherford - DPCo )';

D. N. Miskiewicz - FPC R. C. Widell -

FPC R. L. Miller -

GPUN J. W. Langenbach - GPUN -

S. W. Rutter -

SMUD J. V. McColligan - SMUD  ;

R. J. Gradomski - TED L. A. Haack - TVA C. J. Hudson -

B&W W. T. O'Connor -

TED R. W. Ganthner - B&W l .

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