ML20211M598

Safety Evaluation of Projected Values of Matl Properties for Fracture Toughness Requirements for Protection Against PTS Events

ML20211M598
Person / Time
Site:	Trojan File:Portland General Electric icon.png
Issue date:	12/11/1986
From:	Office of Nuclear Reactor Regulation
To:
Shared Package
ML20211M582	List: ML20211M578 ML20211M598
References
REF-GTECI-A-49, REF-GTECI-RV, TASK-A-49, TASK-OR TAC-59991, NUDOCS 8612170368
Download: ML20211M598 (3)

Text

. . _ _ _ _ _ _ _ _ . -

e fM4 9

[f

, o #o g UNITED STATES g NUCLEAR REGULATORY COMMISSION

';;  : E WASHINGTON, D. C. 20555 a

\,.....)

SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION REGAPOING PROJECTED VALUES OF MATERIAL PROPERTIES FOR FRACTURE TOUGHNESS REQUIREMENTS FOR PROTECTION AGAINST PRESSURIZED THERMAL SHOCK EVENTS PORTLAND GENERAL ELECTRIC COMPANY TROJAN NUCLEAR PLANT DOCKET N0. 50-344 INTRODUCTION As required by 10 CFR 50.61, " Fracture Toughness Requirements for Protection l Against Pressurized Thermal 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 gNkng(at the values inner from the vessel 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 infonnation indicate a significant change in projected values."

By letter dated January 23, 1986, the Portland General Electric Company (the licensee) submitted projected values of RT together with material properties and fast neutron fluence of reabIbr vessel beltline material for the Trojan Nuclear Plant. The RT ar.d fluence values were based on 32 PTS effective full power yea.s.

EVALUATION OF THE MATERIALS ASPECTS The controlling beltline material from the standpoint of PTS susce, ibility was identified to be the lower shell plate B9983-1. The material properties r of the controlling material and the associated margin and chemistry factor were reported to be:

Utility Submittal Staff Evaluation Cu (copper content, %) 0.16 0.16 Ni (nickel content, %) 0.62 0.62 I (Initial RTNDT, F) 10 10 8612170368 861211 4 DR ADOCK 0500

t

/~

M(Margin,*F) 48 48 CF (Chemistry Factor, 'F) 99.9 The controlling material has been properly identified. The justifications given for the copper and nickel contents and the initial RT N are acceptable.

ThemarginhasbeenderivedfromconsiderationofthebasesNrthesevalues, following the PTS 'tule, Section 50.61 of 10 CFR Part 50. Equation 1 of the PTS rule governs, ar# the chemistry factor is as shown above.

-EVALUATION OF THE FLUENCE ASPECTS The methodology of the fluence calculation was based on the discrete ordinates code DOT with an ENDF/B-IV based cross section set. The neutron sources con-servatively did not account for future low leakage loading. In addition it was

- assumed that to the end of the current license that plant will operate at 100%

power which is also conservative. The calculated fluence to the end of license is from 4% to 19% higher than the measured values from capsule X (WCAP 10861, June 1985). The calculated values were assumed in the estimation of the RTPTS *

(The code has been benchmarked by Westinghouse). The lower shell forgoing B9983-1 has been identified as the controlling material, therefore, the applicable value of the fluence for the estimation of the RT is the peak of the azimuthal distribution. Themethodology,thecrosssection$Tkndtheapproximationsused are acceptable. It should be noted that the fluence represents less than 18%

of the fluence required for Trojan to reach the PTS screening criteria.

EVALUATION OF THE CALCULATED RT The limiting beltline material is Plate B9983-1. The equation specified in 10 CFR 50.61, as applicable for the Trojan plant is:

0 RT PTS = I+M+(-10-470xCU+350xCUxNi)xf .27 where: I = Initial RTNDT = 10*F F = Uncertiantly Margin = 48*F Cu = w/o Copper in lower shell forging 89983-1= 0.16 Ni = w/o Nicket in lower forgin B9983-1 = 0.62 f =PeakAzimuthalFluence(E1.0MeV)lowD shell forging B9983-1 in units of la n/cm2 = 2.89 Therefore, for 32 effective full power years (beyond end of license) 0 PT PTS = 10+48+(-10+470x0.16+350x0.16x0.62)x2.89 27

= 58+99.9x1.33 = 191*F which is lower than 270*F the applicable PTS rule screening criterion and is acceptable.

l

CONCLUSIONS The ifcensee has calculated a RT of 191 F for plate material at the end of the nominal 32 EFPY considered 1$Tkhe development of the PTS Rule. This is less than 270'F which is the screenir.g criteria for the limiting material at expiration date of the license. This is acceptable. However, in order for the staff to confirm the licensee's projected estimated RT throughout the life of the Trojan operating license, the licensee is requ$lked to submit a re-evaluation of the RT and comparison to the predicted value with future Pressure-Temperature su$dkttals which are required by 10 CFR 50, Appendix G.

Date: December 11, 1986 PRINCIPAL CONTRIBUTORS:

- P. Randall L. Lois e

,_ _ _ _ . _ _ _ _ _ , . _ , . . - . . . _ . , - . _ _ . _ _ ~ _ _ _ _ _ _ _ . - - - - . _ . . - _ _

_ . _ _ __, - _ . _ _ _ . _ _