ML20207S623

Safety Evaluation Supporting Util 860122,0812,1028 & 870204 Submittals Re Fracture Toughness Requirements for Protection Against PTS Events

ML20207S623
Person / Time
Site:	Yankee Rowe
Issue date:	03/10/1987
From:	Office of Nuclear Reactor Regulation
To:
Shared Package
ML20207S618	List: ML20207S617 ML20207S623
References
NUDOCS 8703200105
Download: ML20207S623 (5)

Text

.

8 g UNITED STATES

[ p, NUCLEAFf REGULATORY COMMISSION l r,,  ; p A WASHINGTON, D. C. 20555 1

+* ij l

....+ J  !

_ SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION REGARDING FRACTURE TOUGHNESS REQUIREMENTS FOR PROTECTION AGAINST PRESSURI ED THERMAL SH0CK EVENTS YANKEE ATOMIC ELECTRIC COMPANY YANKEE NUCLEAR POWER STATION DOCKET NO.50-029 INTRODUCTION As required by 10 CFR 50.61, " Fracture Toughness Requirements for Protection 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 vesselsurface)ofreactorvesselbeltlinemateriaN3(attheinner by giving values 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 infonnation indicate a significant change in projected values."

By letters dated January 22, August 12, October 28, 1986 and February 4, 1987, the Yankee Atomic Electric Company, the licensee for the Yankee nuclear power station, submitted information on the material properties and the fast neutron fluence (E>1.0 MeV) of the reactor pressure vessel in compliance with the requirements of 10 CFR 50.61 (References 1, 2, 3, and 4).

The RT and fluence values were projected to 32 effective full power years (EFPY)pMichisbeyondtheexpirationdateoftheoperatinglicense.

EVALUATION OF THE MATERIALS ASPECTS The controlling beltline material from the standpoint of PTS susceptibility was identified to be lower shell course plate - Lukens Heat No. 19244-3.

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

Utility Submittal Staff Evaluation Cu(coppercontent,%) 0.20 0.20 Ni (nickel content, %) 0.63 0.63 I (Initial RT F) +30 +30 M (Margin,*FIDT, +48 +48 CF (Chemistry Factor, *F) -

128.1 8703200105 870310 PDR ADOCK 05000029 P PDR

The staff concludes that the controlling material has been properly identified. The justifications given for the copper and nickel contents and the initial RT are acceptable. The margin has been derived from consideration $kTthe bases for these values, following the PTS Rule, Section 50.61 of 10 CFR Part 50. Equation 1 of the PTS rule governs, and the chemistry factor is as shown above.

EVALUATION OF THE FLUENCE ASPECTS l The methodology was based on P scattering approximation and ENDF/B-II cross sections; however, a correctiolil factor was estimated by comparison of the results to benchmarking experiments and calculation based on the P approximation and ENDF/B-IV cross section set (Referance 3 and 4).3 The radial power distribution was based on cycles 12-15 which .ar estimated to represent a reactor lifetime source average. Finally an axial flux distribution factor of 1.2 was assumed which is conservative. The methodology and the approximations used for the estimation of the fluence are acceptable.

The lower shell plate has been identified as the controlling material, therefore, the applicable value of the fluence for the estimation of the RT PTS is the peak of the fluence on the lower shell plate. For 32 effective full power years of operation 3ghe acgmulated peak fluence on the lower plate was estimated to be 3.168x10 n/cm EVALUATION OF THE CALCULATED RTn73 The equation specified in 10 CFR 50.61, as applicable for the Yankee plant is:

0 RT PTS = I+M(-10+470 x Cu+350 x Cu x Ni) xf .27 where: I = Initial RT = 30*F M = Uncertainty Margin = 48*F l Cu = w/o Copper in lower shell plate = 0.20 i

Ni =w/o Nickel in lower shell plate = 0.63 f = Peak Azimuthal Fluence (E>1.0 MeV) on gwer sgell plate in units of 10 n/cm =3.168 Therefore, for 32 effective full power years of operation:

0.27 RTPTS= =78 30+48+(-10+470

+ 128.1 x 1.365x e0.20+350 252.9 F x 0.20 x 0.63) x 3.168 which is lower than 270'F, the applicable PTS rule screening criterion, and is acceptable. ,

~

CONCLUSION The licensee has calculated a RT of 253 F for plate material at the endof32EFPYwhichisbeyondtN3 expiration date of the operating license.

This is less than 270*F which is the screening criteria for the limiting material at the expiration date of the license, and is therefore acceptable.

However, in order for the staff to confirm the licensee's projected estimated RT throughout the life of the Yankee operating license, the licenseeisEdkuiredtosubmitareevaluationoftheRT p and comparison tothepredictedvaluewithfuturepressure-temperatureIbbmittalswhich are required by 10 CFR Part 50, Appendix G. It should be noted that this reevaluation is a requirement under 10 CFR 50.61 whenever core loading, surveillance measurements, or other information indicate a significant change in projected values.

Date: March 10, 1987.

t

• ~

4 References

1. Letter from G. Papanic, Jr., Yankee Atomic Electric Company to Director, NRR, " Pressurized Thermal Shock Rule, 10 CFR 50,61(b)," dated January 22, 1986.

2. Letter from G. Papanic, Jr., Yankee Atomic Electric Company to E. M.

McKenna, hAR, " Fast Neutron Fluence for the Reactor Vessel,10 CFR 50.61," dated October 28, 1986.

3. Anderson, S. " Analysis of Fast Neutron Flux Levels and End-of-Life Exposure for the Yankee Rowe Reactor Pressure Vessel" dated March, 1981, .

submitted by letter dated August 12, 1986. l

4. Letter from G. Papanic, Jr., Yankee Atomic Electric Company to E. M.

McKenna, NRR, dated February 4, 1987.

F O

. ya, . ,s .g I

Ditdbutionicopies:

y pg_. _ m.

Local PDR

- PAD #1 r/f PADil p/f TNovak, Actg. DD NThompson, DHFT OGC-Bethesda '

EJordan '

BGrimes

-JPartlow

- Glear-PShuttieworth

- ACRS (10)

LFMB-(TAC'#59997)

GVissing LLofs 1

1 i

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