ML20214N194

Safety Evaluation Supporting Licensee 860117 Response to 10CFR50.61 Re Projected Values of Matl Properties for Fracture Toughness Requirements for Protection Against Pressurized Thermal Shock Events

ML20214N194
Person / Time
Site:	Crystal River
Issue date:	09/04/1986
From:	Office of Nuclear Reactor Regulation
To:
Shared Package
ML20214N180	List: ML20214N179 ML20214N194
References
REF-GTECI-A-49, REF-GTECI-RV, TASK-A-49, TASK-OR NUDOCS 8609160150
Download: ML20214N194 (3)

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UNITED STATES

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{; g NUCLEAR REGULATORY COMMISSION 74 - j WASHING TON, 0. C. 20555

\ .... SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION REGARDING PROJECTED VALUES OF MATERIAL PROPERTIES FOR FRACTURE TOUGHNESS REQUIREMENTS FOR PROTECTION AGAINST PRESSURIZED THERMAL SH0CK EVENTS FLORIDA POWER CORPORATION, ET AL.

CRYSTAL RIVER UNIT NO. 3 NUCLEAR GENERATING PLANT DOCKET NO. 50-302

!_NTRODUCTION 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 surface) of reactor vessel beltline materials by gUing(at valuesthe 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 information indicate a significant change in projected values."

By letter dated January 17, 1986, Florida Power Corporation (the Licensee) submitted projected values of RT together with material properties and fast neutron fluence of reactor Esel beltline material for the Crystal River Unit No. 3 Nuclear Generating Plant (CR-3). The RT and fluence talues were projected to the expiration date of the curreNblicense and for 32 effective full power years of operation.

i l [VALUATIONOFTHEMATERIALSASPECTS The controlling beltiine material from the standpoint of PTS susceptibility was identified to be the middle circumferential weld (Weld WF-70), weld wire j heat number 72105. The licensee's submittal references a B&W report, SAW 1895, January 1986, as the basis. In the Ball report it is stated that there is a

! small probability that the controlling wald contains " atypical weld metal," an I off-specification material that B&W found in 1978 in a test piece welded with wire heat number 72105. This was the subject of Topical Report BAW 10144-A, which was reviewed by the staff on December 12, 1979. Based on a limited amount of test data developed by B&W, the submittal states that the screening criterion will not be reached before end of life even if the atypical weld metal is present. The staff does not disagree with the B&W evaluation of this material, although their evaluation does not follow the procedure for calculating RT given in the PTS rule. (The formula for RT PTS wasdevelopedwithoutconsidbtionoftheatypicalweldmetal.) The staff believes that the probability of occurrence of atypical weld metal in vessel 0609160150 060904 9 PDR ADOCK 0500

welds is lcw enough and its properties are such that the result: of a plant-specific probabilistic risk analysis would not be affected significantly if the atypical weld metal was considered to be present. Thus, the materials input to the calculation of the RT P will be evaluated without further considerationoftheatypicalweldJ5tal.

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

Utility Submittal Staff Evaluation Cu(coppercontent,%) 0.35 0.35 Ni(nickelcontent,%) 0.59 0.59 I (Initial RTPTS, F) 0 0 M(Margin,*F) 59 59 CF (Chemistry Factor, *F) - 2

26.8 CONCLUSION

S The controlling material has been properly identified. The justification given for the copper and nickel contents and the initial RTN are acceptable. The margin has been derived from consideration Of the 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 The maximum azimuthal fluence at the limiting weld material, the middle ire heat number 72105, was determined to be circumfergtialgeld(WF-70),wegw/cm 0.72 x 10 n/cm and .098 x 10 n 2

at the end of the current license and for 32 effective full power years (EFPY) respectively. The Crystal

River 3 flux and fluence calculations were performed using a discrete 4

ordinates code (DOT) and plant specific sources based on previous cycles.

Last cycle sources were used to extrapolate to future cycles. The critical 4

material was identified to be the middle circumferential weld WF-70, thus,

the peak azimuthal and longitudinal flux was used in the calculation of the

! RT sun 5. The DOT 111ance transport capsule calculations results. The method haveof been compared fluence to is calculation the latest l conservative and acceptable.

! According to the PTS Rule, 10 CFR 50.61, the applicable equation for j calculating RT IS PTS 0

l RT PTS = I+M+(-10+470 Cu + 350 Cu N1)f .27

o Where: I = initial RT NDT

=04 M = uncertainty = 59 F Cu =  % copper in weld WF-25 = .35 Ni =  % nickel in weld WF-25 = .59 f = peak fluence (E 2 1.0 MeV) on weld 2

WF-70 (x 10-I9 cm /n) = 0.72 for end of current license

= 0.98 for 32 EFPY Then, to the end of the current license:

0 RT PTS = 0+59+(-10+470x0.35+350x0.35x0.59)0.72 27 RTPTS = 59+226.8x0.915 = 266.5'F for circumferential weld material the governing screening criterion at the expiration date of the license is 300*F. 266.5'F is less then 300*F. This meets the requirements of the PTS Rule and is acceptable. Similarly for 32 EFPY the estimated RTP = 59+226.8x.9946 = 284.6"F which is also less than the applicable 10 CFR g.61 criterion.

CONCLUSIONS The licensee has calculated a RT of 266.5'F for the limiting circumferential weldmaterialattheexpiration01keofthelicense. This is less than 300*F which is the screening criterion for the limiting material at expiration date of the license. This is acceptable and thus meets the requirements of the PTS Rule.

In order for us to confirm the licensee's projected estimated RT throughout the life of the license, we request the licensee to submit a reehlkuation of the RT and comparison to the predicted value with future PressureSMperaturesubmittalswhicharerequiredby10CFR50,AppendixG.

Date:

Contributers to this SER: P. N. Randall L. Lois G. Vissing