ML20153G659

Notifies of Issue Re Potential Impact of Pressurized Thermal Shock Temp Ref in BAW-1975 & BAW-1920P.Use of 0 F May Not Be Conservative to Use as Initial Temp Points for WF-70.B&W Owners Group & NRC Evaluating Issue

ML20153G659
Person / Time
Site:	Three Mile Island
Issue date:	09/06/1988
From:	Hernan W Office of Nuclear Reactor Regulation
To:	Hukill H GENERAL PUBLIC UTILITIES CORP.
References
NUDOCS 8809080320
Download: ML20153G659 (6)

Text

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A DISTRIBUTION

$~ NRCM&^e~i Local PDRs Edordan BGrimes Gray File ACRS(10)

Docket No. 50-289 SYarga BBoger Mr. Henry D. Hukill, Vice President SNorris and Director - TMI-1 RHernan GPU Nuclear Corporation OGC P. O. Box 480 CCheng Middletown, Pennsylvania 17057 DElliot

SUBJECT:

PRESSURIZED THERMAL SHOCK REFERENCE TEMPERATURE FOR BABCOCK AND WILCOX REACTOR VESSELS A recting was held at NRC Headquarters on July 14, 1988 (reeting minutes attached) with the NRC staff, the Sacramento Municipal Utility District (SMUD),andBabcockandWilcox(B&W)todiscussthepressurizedthermalshcck reference temperature (RTpts) for the Rancho Seco reactor. The teeting followed staff review of a letter dated June 16, 1988 in which SMUD responded to staff concerns regarding RTpts for WF-70 weld material. WF-70 weld raterial is used in the Rancho Seco reactor vessel and other reactor vessels ranufactured by B&W, including the TMI-1 reactor vessel.

At issue was the appropriate value of the initial RTpts for unirradiated WF-70 material. The Code of Federal Regulations,10 CFR 50.61, specifies that if a measured initial reference temperature is not av611able then a generic mean value of 0 degrees F must be used for the subject rattrial and the margin to account for uncertainties is increased accordingly. The Pancho Seco Updated Safety Analysis Report assures 0 degrees F as the initial RTpts. The initial RTpts is used along with accumulated neutron fluence and the uncertainty nargin to corpute RTpts during the operating life of the reactor vessel.

Recent publicaticns by Babcock and Wilcox (BAW-1975 and BAW-1920P) identify pessible values for the initial RTpts of WF-70. Although the RTpts reasure-nents conducted to date may not reet the ASME Code Criteria for neasuring initial RTpts, the test results appear to indicate that the initial RTpts of unirradiated WF-70 may be considerably greater than 0 degrees F. Hence, it ray not be conservative to use O degrees F as the initial RTpts for WF-70.

Based en availeble data, it does not appear that the Rancho Seco reactor vessel has reached the screening criteria as defined by 10 CFR 50.61.

However, the test results raise concerns that the screening criteria ray te reached son.etime in the near future.

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-2 A second meeting was held between members of the B&W Owners Group and the NRC staff on August 24 to further pursue this issue on a generic basis. During this neeting the Owners Group outlined a WF-70 evaluation program with NRC u? dates over the next 18-month period (see Enclosure 1). An evaluation, using t1ree different methods, was presented showing margin to the PTS screening 1 criteria for each plant containing WF-70 weld material (see Enclosure 2).

This evaluation shows TMI-1 as not reaching the screening criteria during the life of the plant if the value of 0 degrees F is used and is valid. Should the Owners Group evaluation indicate that a higher initial value of RTpts is appropriate, the screening criteria could be reached during the lifetine of the plant, conceivably in the next several years.

The purpose of this letter is to notify GPU Nuclear of this issue in that it could inipact operation of TMI-1 at sore future date and to request that >cu inform the NRC staff of any TMI-1 plant-specific infornation regarding WF-70 welf material that may in: pact compliance with 10 CFR 50.61 or continued plant ope ra tion.

Sincerely,

% e W

Renald W. Hernan, Senior Project Manager Project Directorate I-4 Divisicn of Reactor Projects I/II Office of Nuclear Reactor Regulation

Enclosures:

As stated LA:PDI-4h- PM: POI-4 D:b SNorris RHernan:ch JSto' 09/@88 09/-9488 09/cL/88 1

l

Enclosura 1 B&WOG CF=70 EVALUATION PROGRAM SCHEDULE 1988 1989 1990 r SEP OCT NOV DEC J F M A M J J A 8 0 N D lJ F M l l l 1 Determine PWHT Effeet on Charpy Props l l l A.Cbta!n Efand Material l: .

j l

B. Test Efand Waterial l  : l l C. Test Archive Waterial l  : I l

D. Evaluate PWHT Elfeet l l

! l l l 2. Confirm Weld Wire Sign!ficance l l:  ;

l Compare trJtla! Pro;ertie: of l l l 6ame Wire Different Flux l l l l l l

3. Determine PWHT Effect on Charpy Props l  ! l A. Prepara Samples ter Mero Stru:tura l l:  : l Stafy (WF 70 L Other) l l l' 8.Cor sare Kero Structure for Different PWHT l l  :  :

O.Ev !uate Results  ! l  ;

l l l 4.LD Effect of Heat input On Charpy Props  !  ! j A. Produce Welds with Varying Heat input l ll j B. Determlns Unittadiated Properties l l * '

l C. Evaluate Results l

l l

l ll l

5. Improve Predletions of Fluence Etfacts l:  !. l Update RTNDT vs o Correlations l l l l l l

6. Provide Data for Long Term l l l A. Encapsulate WF 70 in Lifex Capsules l l: :l B. Irradiate Lifex Capsules l l l -*-

l l l

7. NRC interaction j j j .

A. Updates l l V V Vl V B. Submittats (As necessary) l l l l l l

- _ - - - - - - - - - - - - - - - - - - - - - - - - - - - -- - - - - ---- - - - - - -- L

l

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Evaluation of Various Initial RTNDT and Shift Models on Meeting PTS Screening Criteria screcales Est. Initial Value RTer.F Rimi Shifted (EOL).F Norgin 32 EFFT Criteria het Flecoce Screcalme Plant Weld Location 32 EFFT Ripts M 1.99/2 1993/1 RTpts AG 1.99/2 1993/1 F Ring,F Crtteria EFPT Cal. Yr.

1MI-I Upper circumferential (ISSE) 5.90E*10 9 - -

197 -

59 256 300 >32 -

+24 - -

101 76 201 300 >32 -

-1 - -

137 61 197 300 >32 -

CR-3 Middle circesferential (2001) 1.06t+19 0 - -

230 -

59 209 300 >32 -

+24 - -

214 76 314 300 ~25 2013

-1 - -

175 61 235 300 >32 -

RS teuer lengttodinal (1.0. 731) 0.0E*18 0 - -

219 -

59 270 2M 47 2014

+24 - -

203 76 303 2M . IS 2003-

-1 - -

163 61 226 2M >32 -

Zion 1 Middle circumfereettal (ISSE) 1.7E*19 e - -

262 -

59 321 300 44 2007

+24 - -

242 76 342 300 ~I6 1997

-1 - -

206 61 266 300 >32 -

Zion 2 Upper longitedici (2001) 7.9[+18 0 - -

213 -

59 272 2M ~31 20t5

+24 - I- 197 76 297 2M 41 2003

-1 1 - -

156 61 216 2M ?32 -

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• Enclosure 3 1 o . .* .

t MEETING MINUTES SUBJ: RANCHO SECO REACTOR YESSEL PRESSURIZED TPERNAL SHOCK

a. .

DATE: THURSDAY, JULY 14, 1988 LOCATION: NRC FEADQUARTERS, RDCKV2LLE, MD PARTICIPANTS: STEVE RUYTER, BMUD C.Y. CH$NG, NRC ART LOWE, B&W SAM LEE, NRC JIM TAYLDR, B&W PRYORN RANDALL, NRC MICHAEL MAYFIELD, NRC KE!TH WICHMAN, NRC BARRY ELLIOT, NRC GEORGE KALMAN, NRC DISCUSSION: The meeting was requested by the NRC staff to discuss apparent discrepancies in the value for the pressurized thermal shock initial ref erence temperature (RTpts) f or WF weld material. The Rancho Seco USAR assumes O degrees F. as the initial RTpts (measured value not available). SMUD ,

correspondence (2/23/8B Itr to E. Southard) and SkW publications (BAW-1975 and BAW-1920P) indicate that the initial RTpts may be 59 degrees F. If the initial RTpts is revised to 58 degrees F. ,

the Rancho Seco reactor vessel would be subject to the screening criteria per 10 CFR 50.<st during the next several years.

BLW presented proprietary graphs which included initial RTpts

' test resul t s f or WF-70. Some of the test results indicated that the initial RTpts may be as high as 74 degrees F. When asked what their initial RjT ta estimate would be, based on available test results thW rnied that their best estimate is 23 degrees F. /

A caucus by the NRC participants f ollowing the joint meeting concluded thats (1) Based on the presented D&W test data, O degrees F. does not appear to be an appropriate initial RTpts (a higher temp.

would be expected).

(2) The NRC participants can not determine from the data presented what the initial RTpts should be.

(3) The NRC will continue to review this issue internally and send any additional conclusions to SNUD/B&W.

George Kalman

.m _._

. Mr. Henry D. Hukill Three Mile Island Nuclear Station, GPU Nuclear Corporation Unit No. 1 cc:

G. Broughton Richard Conte O&M Director, THI-1 SeniorResidentInspector(TP.!-1)

GPU Nuclear Corporation U.S.N.R.C.

Post Office Box 480 Post Office Box 311 Middletown, Pennsylvania 17057 Middletown, Pennsylvania 17057 Richard J. McGoey Manager, PWR Licensing Regional Adminihtrator, Region I GPU Nuclear Corporation U.S. Nuclear Regulatory Connission 100 Interpace Parkway 475 Allendale Road Parsippany, New Jersey 70754 King of Prussia, Pennsylvania 19406 C. W. Sryth Robert B. Borsum TPI-1 Licensing Panager Babcock & Wilcox GPU Nuclear Corporation Nuclear Power Generation Division Post Office Box 4F0 Suite 525 Fiddletown, Pennsylvania 17057 1700 Rockville Pike Rockville, Maryland 20852 Ernest L. Blake, Jr., Esq. Governor's Office of State Planning Shaw, Pittran Potts & Trewbridge and Developtr<nt 2300 N Street, N.W. ATTN: Coordinator, Pennsylvania Washington, D.C. 20037 State Clearinghouse Post Office Box 1323 Harrisburg, Pennsylvania 17120 Larry Hochendor.er Thonas M. Gerusky, Director Dauphin County Connissicrer Bureau of Radiation Protectior Dauphin County Courthouse Pennsylvania Cepartirent cf Front and Varket Streets Environmental Resources Harrisburg, Pennsylvania 1712C Post Office Box 2063 Harrisburg, Pennsylvania 17120 David D. Fazwell, Chairran Docketing and Service Section Peard of Supervisors Office of the Secretary Londonderry Township U.S. Nuclear Regulatory Ccu ission RFDt1 - Geyers Church Road Washington, D.C. 20555 Middletown, Pennsylvania 17057