ML20082T200
| ML20082T200 | |
| Person / Time | |
|---|---|
| Site: | Brunswick  |
| Issue date: | 09/10/1991 |
| From: | Watson R CAROLINA POWER & LIGHT CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NLS-91-232, TAC-79381, NUDOCS 9109180147 | |
| Download: ML20082T200 (4) | |
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e CD&L Carolins Power & Light Company P O Bon 1551 e neiegh N C 27tc2 SERIAL: NLS 91232
.SEP 101991 R. A. W AlsON Senkw Vene Preedent Now oewsWn United States Nuclear Regulatory Commisslun ATTENTION: Document Control Desk Washington, OC 20555 DRUNSWICK STEAM ELECTRIC PLANT, UNil NO.1 DOCKET NO. 50-32S/ LICENSE NO. DPR 71 FEE 0 WATER NOZZLE N4D SAFE END UT INDICATION (NRC TAC NO. 79381)
Gentlemen:
On May 23,1991, representetives from Carolina Power a Light Company and the Nuclear Regulatory Commission met to discuss a crack indication identified through ultrasonic inspection in onn of the N40 feedwater nozzle safe end attachment welds at the Brunswick Steam Electric Plant, Unit 1. A meeting summary was issued by the Staff by letter dateo May 31,1991.
Curing the meeting, CP&L indicated thn data obtained from the crack arrest verification system (CAVS) would be used to monitor crack prowth rate conditions in the reactor coolant system. The Company further a,tated that if excessive crack growth rates were postulated for the N4D nozzle indication, based on the CAVS data, that additional actions would be initiated, including unit shutdown, if deemed appropriate.
On August 8,1991, the NRR Projf.::t Manager requested that CP&L provide a written response identifying the Company's intended actions b:: sed on the CAVS system monitoring described above. Carolina Power & Light Company's intended actions concerning crack growth monitoring for the N40 nozzle safe end are es follows:
1.
Crack growth rate data for the Inconel 182 specimen from thu Crack Arrest Verification (CAV) System will be obtained:
a.
At least every 30 days, and b.
Within 7 days following a reactor scram.
2.
The data will be analyzed and compared to the projected crack growth rate. If the crack growth rate observed in the CAV system specimen should exceed the projected crack rate, then:
a.
CAV system data will be obtained every 7 days until the obscived crack g owth rate returns to less than the projected crack growth rate.
b.
An engineering analysis will be performed to determined whether the observed growth rate represents a short term or long term transient, if the observed growth rate !s determined to represent a short term trend, crack 9109160147 910910 s >
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-I e-Document Control Desk NLS-91232 ! Page 2 growth rate data will continue to be obtained svery 7 days until the observed crack growth rate is less than the projected growth rate, if CAV system monitoring indicates a crack growth rate exceeding 2.45E 5 inches per hour for a continuous period in excess of 30 days, an engineering evaluations will be performed, if the evaluation results in a projected crack size which would exceed the ASME Code,Section XI allowable flaw size before the end of the current 18 month operating cycle, plans will be implemented to shut down Unit 1 b3 fore this size is reached and the NRC will be notified. An ultrasonic examination of the flew will be made to determine if changes have occurred.
in the event that the CAV system specimen monitoring reveals a crack growth rate above the projected growth rate on repeated occasions, without a continuous t ceeding 30 days, then the cummulative days of excessive growin r.a will also be analyzed when the commutative d ya exceeds thirty.
The Company is including, for the Staff's information, a chart depicting the Drunswick Unit 1 CAV system data for the inconel 182 specimen. The chart shows the postulated crack growth (i.e.,
crack depth) in comparison to the observed crack growth.
Please refer any questions regarding this submittal to Mr. W. R. Murray at (019) 546 4061.
Yours very truly, fhkjdhDW R. A. Watson WRM/wrm (ulnozzle.wpf)
Enclosure cc:
Mr. S. D. Ebneter Mr.N.B.Le Mr. R. L Prevatte
ENCLOSURE 1 BRUNSWICK STEAM ELECTRIC PLANT, UNIT 1 NRC DOCKET NO. 50 325 OPERATING LICENSE NO. DPR 71 FEEDWATER NOZZLE N4D SAFE END UT INDICATION (NRC TAC NO. 79381) r i
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l BRUNSWICK UNIT 1 C.A.V. SYSTFM DATA l
INCONEL 182 SPECIMEN CRACK GROWTH
SUMMARY
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l ACTUAL ASSUMED CRACK LENGTH IN INCHES (Zerced to start) o.4 l Analyzed Crack Length nd of ^.8 Month Cycle [
02 Out of Serece 1 weeI 0.1 0.0 l
o sooo 10000 15000 l August 15, 19 91 l {CAV System Hours) s l
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