BSEP-94-0042, Informs of Rev in Schedule for Completion of Liquid Penetrant Exam of Bsep,Unit 2 Core Spray Sys Sparger Bracket Welds & Seal Weld Application
| ML20063G094 | |
| Person / Time | |
|---|---|
| Site: | Brunswick  |
| Issue date: | 02/08/1994 |
| From: | Richard Anderson CAROLINA POWER & LIGHT CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| BSEP-94-0042, BSEP-94-42, NUDOCS 9402150318 | |
| Download: ML20063G094 (4) | |
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Carolina Power & Light Company Roy A. Anderson PO Box 10429 Vice President Southpcut NC 28461 Brunswick Nuclear Plant FEB 0 81994 919 457-2496 SERIAL: BSEP 94-0042 U. S. Nuclear Regulatory Commission ATTENTION: Document Control Desk Washington, DC 20555 BRUNSWICK STEAM ELECTRIC PLANT, UNIT NOS.1 AND 2 DOCKET NOS. 50-325 & 50-324/ LICENSE NOS. DPR-71 & DPR-62 DEFERRAL OF LIQUID PENETRANT EXAMINATION OF UNIT 2 CORE SPRAY SYSTEM SPARGER BRACKET ASSEMBLY WELDS AND APPLICATION OF BRACKET SEAL WELDS Gentlemen:
The purpose of this letter is to inform the NRC of a revision in the schedule for completion of liquid penetrant exe:. mation of the Brunswick Steam Electric Plant, Unit 2 core spray system sparger bracket welds and seat weld application. This work, originally scheduled to be performed during the upcoming B211R1 outage has been deferred until the B212R1 outage. The basis for the revised schedule is provided in Enclosure 1. Enclosure 2 is a list of regulatory commitments contained in this submittal.
Please refer any questions regarding this submittal to Mr. W. Levis at (910) 457-2404.
Very truly yours, 7
A.
. Anderson
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MAT / mat Enclosures cc:
Mr. S. D. Ebneter, Regional Administrator, Region 11 Mr. P. D. Milano, NRR Project Manager - Brunswick Units 1 and 2 Mr. R. L. Prevatte, Brunswick NRC Senior Resident inspector 1 4 q p....
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ENCLOSURE 1 BRUNSWICK STEAM ELECTRIC PLANT, UNIT NOS.1 AND 2 DOCKET NOS. 50-325 & 50-324/ LICENSE NOS. DPR-71 & DPR-62.
- 1 DEFERRAL OF LIQUID PENETRANT EXAMINATION OF UNIT 2 CORE SPRAY SYSTEM SPARGER BRACKET ASSEMBLY WELDS AND APPLICATION OF BRACKET SEAL WELDS Backaround in a [[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]] (NLS-91-303), CP&L provided the results of visual examinations of the invessel core spray piping and spargers for Unit 2, performed during the Reload 9 outage (B210R1). These inspections were performed in accordance with NRC Bulletin 80-13, dated May 12,1980. This submittal also described repairs of a crack indication on the north core spray line.
The crack indication on the north core spray line was repaired by reinforcing the piping using underwater welding techniques to weld a bracket assembly to the core spray piping.
The bracket assembly covers the c.acked tee-box location and consists of an upper and lower bracket welded across the piping arms and tee-box. The brackets provide full structural integrity of the piping, even if the crack indication were to grow to 360 degrees.
In addition, the bracket material and weld filler material are both resistant to intergranular -
stress corrosion cracking (IGSCC). In a Safety Evaluation dated January 14,1994, the NRC concluded that this modification would maintain full structural integrity and support continued operability of the core spray line.
Following the repair, a remote visual examination of the bracket welds was performed which assured the welds to be of acceptable quality for at least one cycle of operation.
Since a vessel drain down was not performed, a liquid penetrant (LP) examination of the bracket welds could not be performed. In the November 27,1991 submittal, CP&L committed to perform an LP examination of the bracket assembly welds and application of
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seat welds to the bracket assemblies during the next Unit 2 reload outage (B211R1).
In addition, not performing a vessel drain down prevented application of seal welds across the open ends of the brackets. 'The seal welds are intended to eliminate the potential for crevice corrosion cracking developing under the brackets. CP&L also committed to complete these seal welds during the B211R1 outage.
j Current Status Carolina Power & Light Company has deferred LP examination of the bracket assembly welds and seal welding of the open ends of the brackets until the next Unit 2 reload outage (B212R1). This work is to be performed when the vesselis drained down for 4
feedwater sparger replacement during the B212R1 outage. The NRC approved CP&L's plans to re-examine the feedwater spargers using an underwater high resolution remote operated camera rather than LP or ultrasonic examination during the upcoming B211R1 outage in a Safety Evaluation dated June 24,1993. Based on this approval, there are no plans to drain down the vessel during the upcoming B211R1 outage. As such, the LP examination of the core spray bracket assembly welds and seal welding of the open ends Page 1 of 2 i
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.j ofithe brackets cannot be performed. To ensure continued operability of the core spray
- line, a remote visual examination of the core spray bracket assembly welds will be q
performed in lieu of the LP examination during the upcoming B211R1 outage.
i As stated above, the seal welds are intended to eliminate the potential for crevice -
.l corrosion cracking developing under the brackets. The sealing of the ends of the brackets j
is only applied to preclude the possibility of future cracking of the welds. Therefore, not installing the seal welds does not affect the ability of the brackets to provide full structural integrity of the core spray piping. General Electric has evaluated the deferral of the application of seal welds and found it to be acceptable for up to two fuel cycles (the brackets were installed during the B210R1 outage). This position is based on available j
data which shows that stress corrosion cracking caused by crevices does not initiate before five to ten years under reactor conditions. Therefore, delay of the seal weld application until the B212R1 outage is acceptable.
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In conclusion, CP&L intends to perform examinations of the Unit 2 core spray system piping repair in accordance with the following schedule.
i Unit 2 Core Spray Pipe Repair Examination Schedule B211R1 Outage B212R1 Outage Bracket Assembly Welds Remote \\ isual Liquid Penetrant
.i Circumferential Cracked
'LW "isual Remote Visual Weld l
The circumferential cracked weld inspections are being performed in accordance with the NRC's Safety Evaluation dated January 14,1994. The results of the above inspections, l
and any necessary evaluations or repairs will be provided to the NRC, Since the bracket assembly provides full structural integrity of the piping, CP&L will discontinue visual examination of the circumferential cracked weld after the B212R1 outage. Subsequent to I
the B212R1 outage, the bracket assembly welds will be visually inspected every refueling outage as committed to in CP&L's November 27,1991 submittal. There are no plans to perform LP inspections of the bracket assembly welds after the B212R1 outage.
Seal welding of the open ends of the brackets will be completed during the B212R1 outage.
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ENCLOSURE 2 BRUNSWICK STEAM ELECTRIC PL. ANT, UNIT NOS.1 AND 2 DOCKET NOS. 50-325 & 50-324/ LICENSE NOS. DPR-71 & DPR-62 DEFERRAL OF LIQUID PENETRANT EXAMINATION OF UNIT 2 CORE SPRAY SYSTEM SPARGER BRACKET ASSEMBLY WELDS AND APPLICATION OF BRACKET SEAL WELDS List of Regulatory Commitments The following table identifies those actions committed to by Carolina Power & Light Company in this document. Any other actions discussed in the submittal represent intended or planned actions by Carolina Power & Light Company. They are described to the NRC for the NRC's information and are not regulatorv commitments. Please notify the Manager-Regulatory Aff airs at the Brunswick Nuclear f' f any questions regarding this document or any associated regulatory commitments.
Committed Commitment date' or outage 1.
Conduct remote visual inspection of the Unit 2 north loop core B211R1 spray bracket assembly welds and circumferential cracked weld.
2.
Conduct remote visualinspection of the Unit 2 north loop core B212R1 spray circumferential cracked weld.
3.
Conduct liquid penetrant inspection of the Unit 2 north loop core B212R1 spray bracket assembly welds.
4.
Complete seal welding of the open ends of the Unit 2 north loop
.B212R1 core spray brackets.
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