ML19305E068

Forwards Analysis of Capsule R from Util Facility Reactor Vessel Radiation Surveillance Program.

ML19305E068
Person / Time
Site:	Point Beach
Issue date:	04/16/1980
From:	Fay C WISCONSIN ELECTRIC POWER CO.
To:	Harold Denton Office of Nuclear Reactor Regulation
Shared Package
ML19305E069	List: ML19305E068 ML19305E071
References
NUDOCS 8004220278
Download: ML19305E068 (4)

Text

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O Wisconsin Electnc rom cowa 231 W. MICHIGAN, P.O. BOX 2046, MILWAUKEE, WI 53201 April 16, 1980 Mr. H. R. Denton, Director Office of Nuclear Reactor Regulation U. S. NUCLEAR REGULATORY COMMISSION Washington, D. C. 20555

Dear Mr. Denton:

DOCKET NO. 50-301 REACTOR VESSEL MATERIALS SURVEILLANCE CAPSULE TEST REPORT POINT BEACH NUCLEAR PLANT UNIT 2 Capsule R of the Point Beach Nuclear Plant Unit 2 Reactor Vessel Materials Surveillance Program was removed in accordance with the schedule set forth in the plant Technical Specifications. The testing, except for wedge-open-loading (WOL) specimens, has been completed and the results are contained in Westinghouse Electric Corporation report WCAP-9635. Five copies of this report are enclosed herewith for your information.

A brief summary report of the results of this testing is attached hereto. While these test results do not appear to support the concept of saturation of irradiation-induced embrittle-ment, EPRI is pursuing the testing of additional surveillance capsules. The test results do support the continued use by Point Beach Nuclear Plant of the transition temperature shift curve discussed in the plant Technical Specifications.

In Mr. A. Schwencer's letter of February 27, 1979 to Mr. Sol Burstein, we were advised that NRC planned to have recom-mendations for testing and analysis of WOL specimens available in early 1980. We would be pleased to receive these recommendations so that we can complete our efforts in this regard.

Very truly yours,

_;7 CL J %7 7'b C. W. Fay, Director Nuclear Power Department Enclosures Ao9/

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SUMMARY

REPORT OF WCAP - 9635 ANALYSIS OF CAPSULE R FROM THE WISCONSIN ELECTRIC POWER COMPANY POINT BEACH NUCLEAR PLANT UNIT NO. 2 REACTOR

VESSEL RADIATION SURVEILLANCE PROGRAM Point Beach Nuclear Plant Unit No. 2 was shut down on March 23, 1979 for its fifth refueling outage, and Capsule R was removed from the reactor vessel in early April. Capsule R resided within the reactor vessel for approximately 5.1 effective full power years of operation. Because of the capsule lead factor (now 3.37), the capsule represents about 53.7% of the reactor vessel life for radiation embrittlement considerations.

This capsule was tested by Westinghouse Electric Corporation as part of EPRI Research Project 1021-3 pertaining to the possible saturation of radiation induced embrittlement in reactor vessel materials. The final report was trans-mitted to Wisconsin Electric by an EPRT. letter dated -March 13, 1980 in which it is stated "...that the results indicate that a saturation of the radiation damage has not occurred.. .". However, EPRI concludes that it is too early to dismiss the concept of embrittlement saturation and is pursuing the testing of eleven additional capsules.

The evaluation of the Capsule R themal monitors indicated that the maximum temperature to which the test specimens was exposed was less than 579 0F.

I Capsule R received an average fast fluence of 2.01 x 1019 n/cm 2 (E> 1 Mev) versus a predicted fast fluence of 2.14 x 1019 n/cm2 (E> 1 Mev).

The materials transition temperature shifts caused by this radiation exposure is presented in Table 5-6 of the report and is summarized as follows:

Transition Temoerature Shift, OF Charpy V-Notch At At At Enerov Level, ft-lbs.

50 ft-lb 30 ft-lb 35 mils Upper Change frcm Material Level level L. Exo. Shelf Unirrad.

1. Intermed. Shell 70 70 85 189 +9 (123V500VA1)

2. Lower Shell 30 35 52 140 -5 (122W195 val)

3. Weld Metal -

230 230 47 -18

4. HAZ (extensive 195 190 166 108 +24.5 data scatter)

5. Correl. Monitor 159 151 167 98 25.5 Material Page 1 of 2

In Figure 5-6 of the report (copy attached hereto), the transition temperature shift versus fluence is shown in comparison to the Westinghouse prediction curves for the three Unit 2 capsules that have been tested. The figure shows that the highest prediction curve (0.25 WT% Cu Weld) is accept-able for continued use for the PBNP Unit 2 reactor vessel heatup and cooldown curves; this is the prediction line referred to on page 15.3.1-7 of the plant Technical Specifications.

Section 6 of the report pertains to the radiation analysis and neutron dosimetry work for Capsule R. One significant aspect of this work is the revised capsule lead factors presented in Table 6-3 of the report.

These lead factors are compared to those presented in WCAP - 9331 (Unit 2, Capsule T, August 1978) as follows:

Lead Factors Capsule WCAP WCAP Identification 9635 9331 V&R 3.37 2.5 T&P 1.94 1.6 S&N 1.79 1.4 The change in the lead factor explains why Capsule R represents about 54% of the reactor vessel lifetime exposure versus the planned 40% by the capsule withdrawal schedule (Table 15.3.1-2 of the plant Technical Specifications).

The wedge-opening-loading (WOL) fracture mechanics specimens were not tested and are simply being stored at this time.

Page 2 of 2 l

l l

1000 500 WELD 500 -

0.25 WT% Cu WELD E (0.30% Cu BASE)

R. OR f 0.20 WT% Cu WELD -

200 g (0.25% Cu BASE) m IIAZ 0.15 WT% Cu WELD 200 - (0.207. Cu BASE)

N .10 O WT% Cu WELD -

100 m (0.15% Cu BASE)

$ N .05 O WT% Cu WELD

$ 001 (0.10% Cu BASE) _

5 a.

50 P e 5 tt s g 50 -

123V500VA1 p

a -

m 5

E 20 -

122W195VA1 -

10 10 l I I11 11 I I I Iilll l I I 11lll 10 18 2 5 1019 2 5 10 20 2 5 10 21 FLUENCE (N/CM2 ), E >1 MEV Tn Figure 5-6. Point Beach Unit No. 2 Material 30 ft Ib Transition Temperature b g

increases as Compared to Westinghouse Predictions "

(frow WC A F - 94 SS~)

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