ML20151B596
| ML20151B596 | |
| Person / Time | |
|---|---|
| Site: | Brunswick  |
| Issue date: | 03/31/1988 |
| From: | Mcduffie M CAROLINA POWER & LIGHT CO. |
| To: | Grace J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| Shared Package | |
| ML20151B599 | List: |
| References | |
| NLS-88-069, NLS-88-69, NUDOCS 8804110050 | |
| Download: ML20151B596 (3) | |
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4B1941h1L cerenne power a ushe company P. O. Box 1551 e Aa4+gh, N. C. 27802 kWt 31 mes M. A. McDUFFIE L3 hour Vice Prosact SERIAL: NLS 069 Nuclear Genershon 3
p Dr. J. Nelson Grace, Regional Administrator c)
United States Nuclear Regulatory Commission 101 Marietta Street, NW
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Atlanta, GA 30303 y?
BRUNSWICK STEAM ELECTRIC PLANT, UNIT NO. 2
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DOCKET NO. 50-324/ LICENSE NO. DPR-62 RESPONSE TO IE BULLETIN 80-13 EXAMINATION OF CORE SPRAY SYSTEM SPARGERS Gentlemen:
IE Bulletin 80-13 requires that examinations of the core spray spargers and in-vessel core spray piping be made during each refueling outage.
The results of these inspections are to be submitted to the NRC within 30 days of completing the examinations.
In accordance with IE Bulletin 80-13, a visual inspection (Periodic Test 90.1) of the core spray spargers and in-vessel core spray piping of the Brunewick Steam Electric Plant Unit 2 was completed February 15, 1988.
A crack indication was identified on the north core spray line outside the shroud on the piping adjacent to the junction box in the heat affected zone near the weld.
After the in-vessel in service examinations were complete, the reactor
. pressure vessel was deflooded and supplemental penetrant and ultrasonic tests were performed on the crack. These examinations revealed the following information:
(1) The crack is through wall (2) The crack is approximately 3.5 inches in length along the inside diameter (3) The crack is approximately 1.75 inches in length along the outside diameter Based on a review of the test results, the crack was apparently initiated from the inside of the core spray line.
Since a thermal fatigue crack would be expected to initiate from the outside of the pipe at this location, it is more likely that this crack is the result of intergranular stress corrosion cracking (IGSCC).
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-Document Control Desk NLS-88-069 / Page 2 I
An evaluation addressing the safety significance of the crack has been performed.
This evaluation is provided in Attachment 1.
The technical basis to support the continued structural integrity of the core spray line for all normal and injection conditions is provided. A discussion of the possible consequences of potential loose pieces from a cracked pipe and the consequences of a postulated loss of coolent accident (LOCA) with a crack in the core spray piping are discussed.
The structural analysis concludes that the integrity of the core spray piping will be maintained for all conditions of operation during the next operating cycle. The loose piece analysis shows that the probability of unacceptable flow blockage of a fuel assembly and unacceptable control rod interference due to loose parts is negligible.
The results of the LOCA analyses show that the inherent conservatisms present in current LOCA analyses more than offset the small amount of leakage through the crack. The impact on the calculated peak cladding temperature is shown to be insignificant. Thus, no change to the present Maximum Average Planar Linear Heat Generation Rate (MAPLHCR) for BSEP-2 is required.
Based on the above conclusions, CP&L believes that BSEP-2 can safely operate with this crack during the next fuel cycle and that no operational changes or restrictions are required.
Please refer any questions regarding this submittal to Mr. Leonard I.
Loflin at (919) 836 6242.
Yours very truly, t
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i M. A. McDuffie BAB/bab(doc \\cor\\ crack) l Enclosure cc:
NRC Document Control Desk i
Mr. W. H. Ruland Mr. E. D. Sylvester l
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