ML20087D100
| ML20087D100 | |
| Person / Time | |
|---|---|
| Site: | Brunswick  |
| Issue date: | 01/10/1992 |
| From: | Vaughn G CAROLINA POWER & LIGHT CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NLS-91-335, TAC-M81880, NUDOCS 9201150185 | |
| Download: ML20087D100 (3) | |
Text
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P O Bos 16$1 e Heleigh, N C 27002 SERIAL: NLS 91335 fJAN101992 o o nuom m. e.
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sw..r r..ra.. o.p rim.ni United States Nuclear Regulatory Commission ATTENTION: Document Control Desk Washington, DC 20555 BRUNSWICK STEAM ELECTRIC PLANT, UNIT NO.1 DOCKET NO. 50 325/ LICENSE NO. DPR 71 FEEDWATER N0ZZLE N4D SAFE END UT INDICATION (NRC TAC NO. M81880)
Gentlemen:
The purposo of this letter is to provido additionalinformation to clarify Carolina Power & Ll ht Company's (CP&L) Intended actions concernin0 crack Crowth 0
monitoring for the N4D feedwater norito safe end attachment wolds at the Brunswick Steam Electric Plant, linit No.1.
By letter dated September 10,1991 (Serial NLS-91-232), CP&L provided a written response to the NRR Project Manager's request of August 8,1991 to identify the Company's intended actions to monitor crack growth rate conditions in the reactor coolant system based on the use of data obtained from the crack arrest verification system (CAVS). In a telephone con"crsation on November 8,1991, the NRR Project Manager requested that CP&L provide additionalinformation clarifying the Company's intended actions based on the CAVS monitorin0 The additional information requested was provided to the Staff by [[letter::05000325/LER-1991-027, :on 911105,hydraulic Control Unit 34-19 Declared Inoperable When CRD Accumulator Low Pressure/High Level Alarm Received.Caused by Decrease in Reactor Temp. Accumulators Recharged & TS Change Underway|letter dated November 27, 1991]] (Serial: NLS 91307).
Based on subsequent telephone discussions with the NRC, the Company has determined that further clarification of the !aformation provided in the Company's November 27,1991 response was needed. The revised response, with the specific revisions indicated by the chanDe bars in the rl ht hand marDin, is as 0
follows:
l l
1.
Crack growth data for the inconel 182 sample from the Crack Arrest Verification System (CAVS) will be obtained:
a.
At least every 30 days, and
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7 a.
Document Control Desk NLS 91-335 / Page 2 b.
Within 7 days of startup following a reactor shutdown or scram.
2.
The data will be raviewed and compared to the maximum projected crack growth rate of 2.45 E-5 inches por hour, which was previously
- analyzed, a.
If the average crack growth rate observed during any 'hirty day period exceeds the projected crack growth rate of 2.45 E-5 inches per hour, the CAVS data will be obtained at least overv seven days until the thirty day average crack growth rate returns to let s than the 2.45 E 5 rate for two consecutive 7 day periods, b.
If tho average crack growth rate observed during any forty-five day period creeds 2.45 E-5 inches per hour, an engineering evaluation wi.i be per. armed using the observed forty five day aveiage crack growth rate to projsct the time at which the feedwater nozzie flaw would be expected to exceed the ASME Section XI allowable flaw size. Plans will be implemented to shut down Unit 1 prior to the projected size exceeding 0.4792 inches, which corresponds to 80 percent of the remaining allowable crack growth necessary to reach the ASME Section XI allowable flaw size of 0.504 inches (based on an initial flaw size of 0.38 inches).
c.
In the event that the CAVS monitoring reveals a crack growth rate above 2,45 E-5 on repeated occasions, without a continuous period exceeding 45 days, then an engineering analysis will be conducted when the number of cumulative days of high growth rate exceeds 45 days.
I d.
If the average crack growth rate observed during any thirty day period exceeds 3.0 E-5 inches per hour, an evaluation will be performed to determine the cause of this high crack growth rate, and reduce it to a level below 2.45 E-5 inches per hour if the average crack growth rate observed through any 45 day.
j period exceeds 3.G E 5 inches per hour, plans will be implemented to shut down Unit 1 within 15 days.
3.
The NRC will be notified if plans are made for Unit 1 shutdown.
During the unit shutdown, an ultrasonic examination of the flaw will be made to determine if changes have occurred since the previous j
I-Document Control Desk NLS 91335 / Page 3 f
ultrasonic examination. The results of the examination shall be submitted to the NRC.
4.
Future plans for inspection, ovaluation, and/or repair as necessary durin0 the next scheduled refueling outage remain as presented at the May 23,1991 meeting between CP&L and the NRC.
Please refer a ty questions regarding this submittal to Mr. W. R. Murray at (919) 546-4661.
Yours very truly, J
M
/
G.E.Vaughn WRM/wrm (commit 3 wpf) cc:
Mr. S. D. Ebneter Mr. N. B. Le Mr. R. L. Prevatte 4
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