ML20150C261

Safety Evaluation Supporting Licensee Assessment to Fracture Toughness Requirements for Protection Against PTS Events,Per 10CFR50.61

ML20150C261
Person / Time
Site:	Catawba
Issue date:	06/28/1988
From:	Office of Nuclear Reactor Regulation
To:
Shared Package
ML20150C251	List: ML20150C248 ML20150C261 ML20150C265
References
NUDOCS 8807120382
Download: ML20150C261 (3)

Text

9 8 o, UNITED STATES

. !" ~h NUCLEAR REGULATORY COMMISSION h WASHING TO N, D, C. 20555

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ENCLOSURE 1 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION FRACTURE TOUGHNESS REQUIREMENTS FOR PROTECTION AGAINST PRESSURIZED THERftAL SH0CK EVENTS (10 CFR 50.61)

DUKE POWER COMPANY, ET AL.

CATAWBA NUCLEAR STATION, UNIT 1 DOCKET NO. 50-413

1.0 INTRODUCTION

In accordance with 10 CFR Part 50.61(b)(1), each pressurized water reactor licensee shall have submitted an assessment of the pressure vessel reference temperature by January 23, 1986. This assessment of the reference temperature at the inner surface of the reactor vessel beltline materials is projected from the time of submittal to the expiration of the license. The assessment must specify the bases for the projection and the assumptions regarding core loading patterns. It must be updated whenever changes in core loadings, surveillance measurements, or other information indicate a significant change in projected reference temperature values.

l 2.0 EVALUATION By letters dated October 1,1985, November 11, 1986, and September 1, 1987, i Duke Power Company, et al., (the licensee) submitted information for Catawba l Unit 1 on the material properties and the fast neutron fluence (E greater than i or equal to 1.0 MeV) of the reactor pressure vessel in compliance with the I requirements of 10 CFR 50.61 (See References 1, 2 and 3),

2.1 Haterial Properties  :

l The controlling beltline material from the standpoint of PTS susceptibility was  !

identified by the licensee to be the intermediate shell forging 411343. The i material properties of the controlling material and the associated margin and l chemistry factor were reported by the licensee to be: '

Licensee Submittal Staff Evaluation

)

Cu (copper content, %) 0.08 0.08 ,

Ni (nickel content, %) 0.89 0.89  !

1 I (Initial RT NDT, F) -8 -8 M(Hargin,*F) _

o8 l CF (Chemistry Factor, 'F) _

52.5 8807120382 080628 ,

PDR ADOCK 05000413 l P PDR l

The results of the staff's evaluation are given in the second column above.

The controlling material has been properly identified. The justifications given for the copper and nickel contents and the initial reference temperature (RTNDT), as defined in the ASME Cede, Paragraph NB-2331, are acceptable.

The margin has been derived from consideration of the bases for these values, following the PTS rule (10 CFR Part 50.61). Based on the reported values of fluence, Equation 1 of the PTS rule governs and the chemistry factor is as shown in the above table.

2.2 Fast Neutron Fluence The following evaluation concerns the estimation of the fluence to the pressure vessel for 32 effective full power years of operation and the equations in 10  !

CFRPart50.61(b)(2). The 32 effective full power years represent a 40-year design life based on an 80 percent capacity factor.

1 The methodology of the fluence calculation was based on the discrete ordinates I code DOT with an ENDF-B/IV based cross section set. The scattering is treated I with a P approximation, plant specific sources were used and the code has been benchmarkedbyWestinghouse. Its predictions for the surveillance capsule locations are within 15% of the measured values. Intermediate shell forging ,

411343 has been identified as the controlling material; therefore, the 1 applicable value of the fluence is the peak of the azimuthal distribution.

The fluence estimate is conservative and no future low leakage core loadings were assumed. The methodology, the cross sections and the approximations used are acceptable.

The applicable equation specified in 10 CFR 50.61(b)(2) for the pressure vessel PTS reference temperature (RTPTS) for Catawba Unit I reactor is the follcwing:  ;

0 RT PTS = I+M+(-10+470xcu+350xCuxNi)xf 27 l Where: I = Initial RT NDT = -8'F M = Uncertainty Margin = 48'F Cu = w/o Copper in intermediate forging 411343 = 0.08 Ni = w/o Nickel in intermediate forging 411343 = 0.89 f = Peak Azimuthal Fltence for 32 EFPY (E greater than or equal to 1.0 MeV) on intermediate forging 411343 in units of 19 2 10 n/cm = 2.1 4

l

e Therefore, for 32 effective full power years of operation, the PTS reference temperature is:

0 RT PTS = -8+40+(-10+470x0.08+350x0.08x0.89)x2.1 27

= 32-52.52x1.222 = 96.2*F This value is considerably lower than 270'F which is the applicable PTS rule screening criterion in 10 CFR Part 50.61(b)(2) and, therefore, the projected PTS reference temperature for Unit 1 is acceptable.

3.0 Conclusion that the pressure vessel PTS reference The staff concludes, temperature based defined in 10 CFR on Partthe above,(b)(2) is less than the applicable PTS 50.61 screening criterion. Because the PTS reference temperature is projected to be within the screening criterion through the expiration of the L' nit i license, the licer.see does not have to address 10 CFR Part 50.61(b)(3). In accordance with 10 CFR 50.61(b)(1), the staff requests that the licensee submit an update to the information provided in its letters dated October 1, 1985, November 11, 1986, and September 1,1987, whenever changes in core roadings, surveillance measurerents, or other information indicate a significant change in projected reference temperature values.

4.0 References

1. Letter from W. H. Owen, Duke Power Company to H. R. Denton NRR, dated October 1, 1985.

2. Letter from H. B. Tucker, Duke Power Company to H. R. Denton, NRR, dated Noventer 11, 1986.

3. Letter from H. B. Tucker, Duke Power Company to Document Control Desk, NRC, dated September 1, 1987.

Principal Contributors: L. Lois, P. N. Randall Dated:

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