ML20245J566

Forwards Util Re Reactor Vessel Fracture Toughness,For Info,Although Subj Considered Outside Scope & Irrelevant to Proceeding,Per Board 890608 Order

ML20245J566
Person / Time
Site:	Turkey Point
Issue date:	06/21/1989
From:	Frantz S FLORIDA POWER & LIGHT CO., NEWMAN & HOLTZINGER
To:	Bright G, Cotter B, Harbour J Atomic Safety and Licensing Board Panel
References
CON-#389-8821 OLA-4, NUDOCS 8907030095
Download: ML20245J566 (10)

Text

. . i 8Y21 NEWMAN Sc HOLTZINGER. P.g g JACK R NEWMAN 66 t5 L. ST R E ET N. W- O WILLIAM C. BAER, JR JOHN E. HOLT,1NGER. JR SUSAN J BELL HAROLD F. REIS WASHINGTON, D.C. 2003 6 DOUGL AS L BERESFORD MAUniCE ANELRAD STEVEN A BROECKAERT*

J A. BOUF NsGHT, JR PATRICIA A COMELLA PAUL H. MEC" 202 955 66OO OAVID B DRYSDALE*

GEORGE L. EDGAR dlLL E GRANT MATHLEEN N SHEA JONATHAN W GREENBAUM DOUGLAS G GREEN ,,,,. DAVID W JENKINS*

e I b. . .I 'L i ,. ELIAS G JOHNSON KAROL LYN NEWMAN JOHN T STOUGM. JR [,( ['r MAUREEN KERRIGAN*

JAMES B VASILE JOANNE C KY ROS MICH# iL A BAUSER PAMELA A L ACEY ALVI., H. GUTTERMAN MICHAEL G. LEPRE*

EDWARO J TWOMEY KENNETH C M ANNE

• KATHLEEN M. MCDERM')TT JAMES,B WILCOX.

KEV,N . GALLE N JR June 21, 1989 LOREN S. MELT,ER THOMAS A SCVVUT, JEFFREY B MULHALL MICHAEL F. HE ALY STEVEN H NEINAST ROBERT 4 WHITE ERROL R. PAfTERSON SCOTT A HARMAN RICHARD L ROBERTS

• i STEVEN P. FRANTI PERRY D. ROBINSON

• l DAVID B RASKIN STEVEN J ROSS* l KEV 4N J LfPSON JANE I RYAN JANET E B ECPER RtCHARD T. SAAS*

CHARLES C. THE BAUD, JR.

JACOLYN A. SIMMONS NANCY A WHITE DONALD J. SILVERM AN JOSEPH E STUBBS ROBERT LOWENSTERN JADE ALICE E ATON HERBERT B COHN  ;

ORaAN R GISH KENNETH M. KASTNEA j cosasco orcounscs 1

'h07 ADWFTED IN D C B. Paul Cotter, Jr. I Glenn O. Bright Jerry Harbour Atomic Safety and Licensing 3 Board Panel q U.S. Nuclear Regulatory Commission i Washington, D.C. 20555 i

Ret Docket Nos. 50-250 OLA - 4 and 50-251 OLA - 4; In the Matter of Florida Power & Light Company  ;

(Turkey Point Plant, Units 3 and 4)  :

Dear Licensing Board Members:

Please find enclosed a copy of a. letter dated June 16, 1989, from C.O. Woody (Florida Power & Light Company (FPL)) to the NRC entitled " Reactor Vessel Fracture Toughness."

This letter provides a response to NRC quesrions concerning upper-shelf energy related to the Turkey Point reactor vessels. In this context, the letter discusses FPL's participation in an owners' group program which, among other +

things, will provide test data for irradiated surveillance capsules from Turkey Point.

l As ruled by the Licensing Board in its Memorandum and Order (June 8, 1989), p. 24, tne issue of "whether the upper- ,

shelf energy of specimens meets the requirements of 10 C.F.R.

I Part 50, Appendix G" is outside the scope of the Pressure /

Temperature Limit amendments for Turkey Point. Therefore, the Licensee believes that the enclosed letter is not relevant to 8907030095 090621 O l PDR ADOCK 0500

$g

NEWMAN & HOLTZINGEH, P. C.

B. Paul Cotter, Jr.

June 21, 1989 Page Two this proceeding. Nevertheless, given the. general subject of the letter, the Licensee is providing the letter for the information of the Licensing Board and the parties.

Sincerely, 3

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"/

Steven P. Frantz Co-Counsel for Florida Power &

Light Company cc: (w/ encl): Service List

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P O Boa 14000. Juno Beach.FL 33408 0420 I: P L SUSB 161989 L-89-190 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D. C. 20555 g(pr3nnfj{3 Gentlemen: L ggjggg O,

Re: Turkey Poiit Units 3 and 4 b- .g l i

j l Docket Nos. 50-250 and 50-251 y Newman ohNger.P.C.

I Reactor Vessel Fracture Toughness i URC Tac Nos. 68249 and 55042 By letter dated May 31, 1988, the NRC provided a Safety Evaluation related to the Fracture Toughness of the Turkey Point Units 3 and 4 reactor vessels. That report identified the need for additional analysis and data' collection.

Attached is Florida Power & Light Company's (FPL) response to that request for additional information.

FPL requested a 30-day extension of the May 31, 1989 submittal date {

specified in the May 31, 1988 NRC letter. That request was granted by the NRC Project Manager for *he Turkey Point Plant on May 25, 1989.

i If you have any questions, please contact us.

Very truly yours, l h lgeh '

C. . Woo Acting Senior Vice President - Nuclear j COW /TCG/cm Attachment cc: Stewart D. Ebneter, Regional Administrator, Region II, USNRC Senior Resident Inspector, USNRC, Turkey Point Plant  :

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ATTACHMENT RE: Turkey Point Units 3 and 4 Docket Nos. 50-250, 50-251 REACTOR VESSEL FRACTURE TOUGHNESS (TAC NOS. 68249 and 55042)

FPL submitted fracture toughness analyses (FPL letter Nos. L84-120

& L86-122) of the beltline welds for the Turkey Point reactor vessels in May 1984 and March 1986. Your safety evaluation of May 31, 1988 identified a need for additional' analysis and data acquisition relative to the upper shelf energy issue. It was further recommended that FI% contact the ASME Section XI Working Group on Flaw Evaluation, which has been working on the A-11 low upper shelf issue since 1982, to determine the impact of their work on Turkey Point.

The purpose of this submittal is to: (1) inform you of what we have accomplished since that time; (2) outline the scope of our 1 future plans; and (3) highlight the conservatism incorporated in the analyses of 1984 and 1986 which assures that adequate margins of safety are being maintained while we continue to pursue these issues.

FPL has participated in the ASME Code Section XI Flaw Evaluation Working Group on A-11, the EPRI embrittlement task team, and the recently formed ASME Section XI Task Group on Margins. Basic issues such as flaw orientation for circumferential welds and appropriate safety factors have been discussed. Significant progress has been made and it appears that a consensus can be reached on the resolution of the A-11 issue.

Therefore, rather than continue to modify our previously submitted analysis of 1984 and 1986, we propose to incorporate the most recent developments in the industry into our characterization of the Turkey Point vessel fracture toughness. These developments include new analytical techniques, the progress made by the Working Groups and the additional material data to be provided by the Babcock & Wilcox Owner's Group (BWOG) as discussed later. We will be pleased to meet with your representatives at their convenience to discuss these activities further.

Based upon information currently available, it appears that the use of charpy data is a good method for detecting irradiation effects on embrittlement but a less ef fective method of determining the

• I effect of irradiation on the ability of the irradiated material to resist tearing.

Page 2 l

Therefore, even if the upper shelf energy of a reactor vessel material specimen is less than the fif ty f t-lbs screening criterion in 10 CFR 50 Appendix G, the reactor vessel may still contain adequate margins of safety against f ailure. Thus, the significance of the upper shelf energy of a material specimen or a limited' number of specimens should be determined within the context of a larger body of data.

In order to obtain more data applicable to the Turkey Point reactor vessels (which were manufactured by B&W), FPL has joined in a collective program with the BWOG.

The program as it relates specifically to the Turkey Point materials will supply 2 additional surveillance capsules which will be irradiated in B & W plants. One surveillance capsule with a target fluence of 3 x 10" will be irradiated at Florida Power Corporation's Crystal River Plant and contain 9 charpy, 3 tension and 3 1T compact tension fracture mechanics specimens. A second capsule to be irradiated at Toledo Edison Company's Davis Besse Plant will contain charpy, tension and 1XWOL specimens. The charpy and tension specimens will be reconstituted from the PTN capsule V and the 1XWOL will be specimens which have been stored and unbroken from capsule V. The 1XWOL's will be appropriately modified to assure valid data is taken. This capsule will be irradiated to a target fluence of 1.7 X 10".

We know from published data that the first capsule from several surveillance programs at other nuclear units has supplied data below 50 ft-lbs and has subsequently supplied higher values after additional irradiation. This behavior is not understood and clearly does not fit any of the existing models. However, to try to determine the reason for the anomalous behavior of one surveillance point, FPL has attempted to lccate additional weld material from weld SA-1094 which is the Turkey Point 4 surveillance material but does not actually exist in the Turkey Point vessels.

Westinghouse, the NSSS vendor for Turkey Point, has been requested to identify any material they might have, but none has been located to date. FPL has used capsule material from Turkey Point, and this material may be suitable for performing a fracture surface examination, and/or a chemical analysis study to determine the reasons for such behavior. This material should be shipped from South West Research Institute to B & W this year, and its suitability for additional testing will be determined at that time.

. w Page 3 In its May 31, 1988 letter, NRC requested an estimate of the charpy upper shelf energy at the next refueling outage and at the expiration date of the Turkey Point Units 3 and 4 operating. The licenses. . Figure 2 is a plot of CV upper shelf vs. fluence.

capsule data is shown on the plot for capsules V and T f rom Turkey Point Unit 3 and capsule T from Turkey Point Unit 4. The current fluence for Units 3 and 4 are approximately 8.5 X 10'8 at the 1/4 T position. The A-9 model referenced on the plot is a regression model based on fluence and chemistry. The Regulatory Guide 1.99 Rev. 2 model is the same as the Rev. 1 model formulated in 1977 which was based on much less data than what is available now and has consistently been extremely conservative.

Although FPL is no longer relying upon its 1984 and 19'86' analyses to demonstrate the acceptability of the Turkey Point reactor vessels over the lifetime of the plant, the results of these analyses provide confidence' that the reactor vessels contain adequate margins of safety pending completion of new analyses using the industry analytical techniques currently being developed. In particular, the 1984 and 1986 analyses include the following conservatism:

1. The analyses assumed a flaw in t'he weld 2 inches deep by 12 inches long oriented axially and radially. Turkey Point Units 3 and 4 only have circumferential welds. This is shown in Figure 1 which shows a schematic of both Turkey Point Units 3 and 4 reactor vessels with- the welds identified. The critical weld in both vessels is the intermediate to lower shell weld No. SA-1101. There are no longitudinal welds since the shell courses are SA 508 Class 2 ring forgings. The most likely orientation for a fabrication induced ' weld flaw to occur would be in the circumferential direction. Locating the flaw in the axial and radial direction 2 inches deep and 12 inches long would, in reality, locate most of the crack 'in the forging material which has much better irradiated' properties.

The assumed crack location and material properties'used.are equivalent to assuming a longitudinal weld which has twice the applied load'due to hoop stresses acting on it. This is a very conservative approach and similar to adding a safety factor of 2.

2. A factor of safety of 2 was applied on pressure assuming a i nominal operating pressure of 2500 psi, resulting in a Pressure of 5000 psi being used in the analysis. However', the power operated relief valve (PORV) setpoints are 2335 psi, the high pressure trip is set at 2385 psi and the code safety.

relief valves are set at 2485 psi. Thus, a safety factor of 2 on a nominal operating pressure of 2500 psi is extremely conservative.

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i Page 4 q l

3. FPL's 1984 and 1986 analyses included additional loads which are not typically considered, such as residual weld stresses )

and pressure.on the crack surface. l

4. Flow stresses were based on unirradiated properties, which is conservative because irradiated properties - ' are higher for j tensile and yield strength. ]

In . addition to these . conservatism mentioned, FPL's analyses assumed the presence of a pre-existing crack 2 inches deep and 12 inches long. FPL has performed inservice inspections of the reactor vessel beltlines and determined that no. detectable defects i existed'. The details of these examinations are listed in Appendix j I. .)

l Our analyses of 1984 and 1986 demonstrated a significant margin of j safety - through end.of life. Based upon these results and the i conservatism mentioned above, FPL concludes that the Turkey Point i reactor vessels will contain an adequate margin pending acquisition j and analysis of the results of the BWOG program.

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61782/8457(SA-1135) 61782-6457(SA-1135)

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ATTACHMENT 1 TURKEY POINT UNIT 4 l REACTOR PRESSURE VESSEL EXAMINATION Each weld and the adjacent base metal for a distance equal to one-half of the wall thickness was examined with ultrasound.

Examinations were conducted in accordance with the requirements of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code and U.S. Nuclear Regulatory Commission Regulatory Gu.de 1.150.

To ensure accuracy, the ultrasonic instruments were adjusted to display specific responses from reflectors of known size and location. The reflectivity of detected flaws was compared to the known responses to determine relative size. Additional characteristics of these detected flaws were analyzed to determine relevance and size. For example, the return signal dynamics were carefully monitored for pattern changes which would be indicative of the presence of a crack.

Special techniques were utilized for the examination of the inner twenty-five percent of the materia] volume. This was to ensure that potentially injurious flaws were detected with adequate reliability. The Unit-4 Reactor Pressure Vessel was subjected to a double examination in this important area. The first examination employed a twin element seventy degree beam to interrogate the first two and one-half inches with high sensitivity. In this examination, the ultrasonic beam was transmitted in a refracted longitudinal wave mode in order to minimize the effects of the contact surface stainless steel cladding. Sensitivity was established with responses from one-sixteenth inch diameter side drilled holes located at the clad-base metal interface and incrementally deeper to the maximum effective search unit depth range.

The second examination employed a " full vee" forty-five degree beam which was directed at the outside surface where it was bounced back to the inner surface at a forty-five degree angle. This ngle is the most favorable for the detection of the " corner" forn -d by a crack and the surface of the material. Calibration was in accordance with established ASME practice which included a .140 inch deep by 2.0 inch long notch located at the clad-base metal interface.

The seventy degree technirIue has a demonstrated capability of detecting cracks, under cladding, of one tenth of one inch deep with a ninety-five percent probability of detection. The redundant forty-five degree examination provided additional assurance that no cracks are present.

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