ML20214T351

Safety Evaluation Re Projected Values of Matl Properties for Fracture Toughness Requirements for Protection Against PTS Events.License Required to Submit Reevaluation & Comparison Results W/Future Submittals

ML20214T351
Person / Time
Site:	Three Mile Island
Issue date:	11/25/1986
From:	Office of Nuclear Reactor Regulation
To:
Shared Package
ML20214T301	List: ML20214T298 ML20214T351
References
REF-GTECI-A-49, REF-GTECI-RV, TASK-A-49, TASK-OR SP, NUDOCS 8612080566
Download: ML20214T351 (3)

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k t ,j UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D. C. 20555 g

....+,o SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACT 0P REGULATION REGARDING PROJECTED VALUES OF MATLiilAL PROPERTIES FOR FRACTURE TOUGHNESS REQUIREMENTS FOR PROTECTION AGAINST PRES 5URIZED THERFAL SH0CK EVENTS GENEPAL PUBLIC UTILITIES NUCLEAR CORPORATION THREE MILE ISLAND UNIT 1 DOCKET NO. 50-289 INTRODUCTION As required by 10 CFR 50.61, " Fracture Toughness Requirements for Protection Against Pressurized Themal Shock" (PTS Rule) which was published in the Federal Register July 23, 1985, the licensee for each operating pressurized water reactor "shall submit projected values of RT surface) of reactor vessel beltline materials by gbng(at the inner values vessel from the time of submittal to the expiration date of the operating license. The assessment must specify the bases for the projection including the assumptions regarding core loading patterns. This assessment must be submitted by January 23, 1986, and must be updated whenever changes in core loadings, surveillance measurements or other information indicate a significant change in projected values."

By letter dated January 23, 1986, the GPU Euclear (GPUN) Corporation, licensee for the Three Mile Island Unit 1 (TMI-1) nuclear plant, submitted information on the fast neutron fluence for the reactor vessel (including longitudinal weld SA-1526, the controlling beltline material) as required by 10 CFR 50.61.

Additional infomation was submitted on May 5 and August 25, 1986. In these submittals, GPUN concluded that the TMI-1 pressure vessel meets the toughness requirements of 10 CFR 50.61 to the end of its current operating license, i.e, May 18, 2008, for which the estimated cuiriulative operation is 21 effective full power years.

Evaluation of the Materials Aspects The controlling beltline material from the standpoint of PTS susceptibility was identified to be a lower longitudinal weld SA 1526 (weld wire heat number 299L44).

The material properties of the controlling material and the associated margin and chemistry factor were reported to be:

Utility Submittal Staff Evaluation Cu (copper content, %) = 0.35 0.35 Ni (nickel content, %) = 0.68 0.68 I (Initial RTNDT, F) = 0 0 M (Margin, "F) = --

59 CF (Chemistry Factor, F) = --

237.8 8612090566 PDR 861125 ADOCK 05000289 PDR

Staf'f evaluations concluded that the controlling material has been pr~nperly identified. Justification by GPUN for the copper and nickel contents and initial P.T are acceptable. The margin has been derived from consideration ofthebaskTfor these values, following the PTS Rule, Section 50.61 of 10 CFR part 50. Assuming that the reported values of flueace are correct, t

Equation 1 of the PTS rule governs,' and the chemistry factor is as shown above.

Evaluation of the Fluence Aspects The methodology of the fluence estimation is similar to that used previously by B&W and it includes a discrete ordinates transport calculation as well as fluence measurements with a surveillance capsule. The calculation was performed by the D0T-4 code using an pS quadrature and a P, approximation for the scattering cross section. The croYs section set CASK Was used which is ENDF/B based and, hence, acceptable. The neutron sources were estimated using PDQ pin-by-pin time averaged power distributions. A comparison of measured to calculated values was performed. The difference was well within the calculational and/or experimental uncertainty. A conservative normalization factor of 5% was applied to calculated values. The methodology, the cross sections and the approximations used are acceptable.

Cycles 1-4 were standard out-in fueled. Cycles 6 and 7 are transition cycles designed for low leakage. Cycle 8 and subsequent cycles are to be designed as very low leakage. With an estimated load factor of 80% it is estimated that by the end of the current license (May 18,2008) the cumulative effective full power years of operation will be 21. Atthislevelofexposurethecogrollipg beltline material, longitudinal weld SA-1526, will accumulate 0.643x10 n/cm of fluence.

Evaluation of the Calculated RT PTS The equation specified in 10 CFR 50.61, as applicable for the TMI Unit 1 plant is:

0 RT PTS

= I+M+(-10+470xCu +350xCuxNi)f .27 where: I = Initial RT =0F M=Uncertainthargin = 59 F Cu = w/o Copper in longitudinal weld SA-1526 = 0.35 Ni = w/o Nickel in longitudinal weld SA-1526 = 0.68 f = peak fluence to the end of cugent{icenseintermsof 10 n/cm 0.64 Tt3refore:

RT = 0+59+(-10+470x0.35+350x0.35x0.68)x(0.64)0.27 RT = 59+(237.8)x(0.886) = 269.8 F But from a significant figure viewpoint this value is 270*F.

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l l The calculated RT is 270 F which is also the pressurized thermal' shock screeningcriteri$Sper10CFP.50.61(b)(2). Any plant for which material in the beltline is projected to exceed the PTS screening criterion before the expiration date of the operating license shall implement necessary flux reduction programs as are reasonably practical to avoid exceeding the PTS screening criterion. Since the calcuated RT does not exceed the screening criterion, no additional flux reduction progNiils are presently required for TMI-1.

CONCLUSIONS The calculated RT P is 270"F for the controlling beltline material from the standpointofPTSIbsceptibilityattheendofthecurrentoperatinglicense j for TMI-1. This calculated value equals but does not exceed the screening criterion for the limiting material at the expiration date of the license and is acceptable. However, in order for the staff to confinn the licensee's projected RT estimate throughout the life of the TMI-1 license, the j licenseeisNkuiredtoperiodicallyreevaluateRT and compare it to predicted values. Thelicenseeisrequestedtosubktthisreevaluationand comparison results with future Pressure-Temperature submittals which are required by 10 CFR 50, Appendix G. This periodic reevaluation is particularly important for TMI-1 because the calculated RT equals the screening PTS criterion.

Date: November 25, 1986 Principal Contributors: L. Lois, P. N. Randall 4

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