BSEP-99-0130, Requests Relief from ASME Boiler & Pressure Vessel Code, Section Xi,Iaw 10CFR50.55a(g)(5)(iii) & NRC GL 90-05, Guidance for Performing Temporary Non-Code Repair of ASME Code Class 1,2 & 3 Piping. Regulatory Commitments,Encl

Requests Relief from ASME Boiler & Pressure Vessel Code, Section Xi,Iaw 10CFR50.55a(g)(5)(iii) & NRC GL 90-05, Guidance for Performing Temporary Non-Code Repair of ASME Code Class 1,2 & 3 Piping. Regulatory Commitments,Encl

ML20211F948
Person / Time
Site:	Brunswick
Issue date:	08/25/1999
From:	Jury K CAROLINA POWER & LIGHT CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
BSEP-99-0130, GL-90-05, NUDOCS 9908310110
Download: ML20211F948 (8)

Text

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b. ,

.CP&_L Carolina Power & Ught Company P,o. Box 10429 Southport, NC 28461-0429

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August 25,1999 10 CFR 50.55a(g)(5)(iii)

SERIAL: BSEP99-0130 l

U. S. Nuclear Regulatory Commission l A'ITN: Document Control Desk )

Washington, DC 20555-0001 l I

BRUNSWICK STEAM ELECTRIC PLANT, UNIT NO.1 DOCKET NO. 50-325/ LICENSE NO. DPR-71 ASME BOILER AND PRESSURE VESSEL CODE, SECTION XI-IN SERVICE INSPECTION F ROGRAM - REQUEST FOR RELIEF TO PERFORM A NON-CODE REPAIR OF S'dRVICE WATER SYSTEM PIPE Gentlemen; The purpose _of this letter is to request relief from the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code,Section XI, in accordance with

- 10 CFR 50.55a(g)(5)(iii), and NRC Generic Letter 90-05, " Guidance For Performing Temporary l Non-Code Repair of ASME Code Class 1,2 and 3 Piping." This request for reliefis applicable to the Brunswick Steam Electric Plant, Unit No.1, and pertains to a through-wall leak identified

- on the Service Water system vital header line 1-SW-110-6-157. The detailed request for reliefis l provided in Enclosure 1. A list of regulatory commitments contained in this letter is provided in j Enclosure 2.

Please refer any questions regarding this submittal to Mr. Warren J. Dorman, Supervisor -

Licensing, at (910) 457-2068.

Sincerely, )

i L ,

Keith R. Jury l Manager - Regulatory Affairs  !

Brunswick Steam Electric Plant j WRM/wrm I 31t'G M ACN i

Enclosures:

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1. Relief Request

2. Iist of Regulatory Commitments j 9908310110 990825 PDR ADOCK 0S000325  !

9. PDR v

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,Docunient Control Desk  ;

BSEP 99-0130 / Page 2

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cc (with enclosures): l U. S. Nuclear Regulatory Commission, Region II ATTN: Mr. Luis A. Reyes, Regional Administrator Atlanta Federal Center 61 Forsyth Street, SW, Suite 23T85 J Atlanta, GA 30303 .3415 l U. S. Nuclear Regulatory Commission '

ATfN: Mr. Theodore A. Eastick, NRC Senior Resident Inspector

- 8470 River Road Southport, NC 28461-8869 U. S. Nuclear Regulatory Commission ATrN: Mr. Allen G. Hansen (Mail Stop OWFN 8G9) 11555 Rockville Pike-Rockville, MD 20852-2738 l 1

Ms. Jo A. Sanford Chair - North Carolina Utilities Commission P.O. Box 29510 Raleigh, NC 27626 4 510 Division of Boiler and Pressure Vessel 1 North Carolina Department of Labor ATfN: Mr. Jack Given, Assistant Director of Boiler & Pressure Vessels 4 4 West Edenton Street .

Raleigh, NC 27601-1092 1 1

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ENCLOSUREI BRUNSWICK STEAM ELECTRIC PLANT, UNIT NO.1 DOCKET NO. 50-325/ LICENSE NO. DPR-71 ASME BOILER AND PRESSURE VESSEL CODE, SECTION XI-IN-SERVICE INSPECTION PROGRAM - REQUEST FOR RELIEF TO PERFORM A NON-CODE REPAIR OF SERVICE WATER SYSTEM PIPE Relief Reauest Unit: 1 Component: Service Water System Vital Header Line Number 1-SW-110-6-157 System: Service Water system Class: 3 Code Requirement: The American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code,Section XI,1989 Edition, subparagraph IWA-4000(a) states: " Repairs shall be performed in accordance with the Owner's Design Specification and the original Construction Code of the component or system."

Generic Letter 90-05," Guidance For Performing Temporary Non-Code Repair of ASME Code Class 1,2, and 3 Piping," defines impracticality to exist if ". . . the flaw detected during plant operation is in a section of Class 3 piping that cannot be isolated for completing a code repair within the time period permitted by the limiting condition for operation (LCO) of the affected system as specified in the plant Technical Specifications, and performance of code repair necessitates a plant shutdown.'

On July 26,1999, a through-wall leak was identified on the Brunswick Steam Electric Plant (BSEP),

Unit No.1 Service Water system vital header line number 1-SW-110-6-157. Completion of a code El-1

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l repair of the defect on this line will require isolation of the Conventional Service Water system header.

i' Although the time period allowed by the Technical Specification LCO for the Service Water system would provide sufficient time to complete a code repair, isolation of the affected line to perform the repair would result in immediate shutdown of the  ;

unit due to the loss of cooling water to the l supported equipment. The Conventional Service Water system header is used as the cooling source for the Turbine Building Closed Cooling Water (TBCCW) system. The TBCCW heat exchangers are the only major heat load on the Conventional Service Water system. The TBCCW system provides cooling for the main generator stator water cooling, generator gas cooling, and bus duct cooling. In addition, the condensate pumps, condensate booster pumps, heater drain pumps, and J feedwater pumps also receive cooling water from TBCCW. Code repair of the defect is impractical because isolation of Conventional Service Water .

system header will result in the loss of the TBCCW f system with immediate shutdown of the unit.

Therefore,in accordance with  !

10 CFR 50.55a(g)(5)(iii), Carolina Power &

Light (CP&L) Company requests relief from the requirements of subparagraph IWA-4000(a) of the ASME Code,Section XI for repair of the identified l defect on line 1-SW-110-6-157, 1 Proposed Action: Engineering evaluation of the defect on the BSEP, Unit i Service Water system vital header line  :

1-SW-110-6-157, using the "through-wall flaw" j approach described in NRC Generic Letter 90-05, j has demonstrated that continued operation of the j component in the as-found condition is structurally j acceptable until the next scheduled outage i i

exceeding thirty days, but no later than the next scheduled refueling outage. Although leakage from l the defect is currently minimal (i.e., approximately l 30 drops per minute), a " soft patch" has been i applied to prevent system leakage. The next l refueling outage for BSEP, Unit 1 is currently i scheduled to begin February 26,2U00. l 1

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' Basis ForThe Proposed Action: Line 1-SW-110-6-157 is part of a moderate energy system and is classified as ASME Code Class 3.

The defect in line 1-SW-110-6-157 is located on an elbow between valve 1-SW-V110 and the 24-inch diameter Conventional Service Water Header (i.e.,

line 1-SW-100-24-154). The affected line is the Service Water supply to the Vital Header from the Conventional Service Water Header. The leak rate currently is approximately 30 drops per minute.

Until line 1 SW-110-6-157 can be isolated and l examined from the inside, the cause of the defect I cannot be definitely confirmed. However, the defect is believed to result from a local failure of the cement liner on the inside of the pipe which has i allowed salt water to come into contact with the  !

carbon steel pipe.  !

1 I

In accordance with the guidance of NRC Generic Letter 90-05, the defect has been examined by the ultrasonic examination (UT) method and wall thickness measurements have been taken. Based on these examinations, the defect has been characterized as a localized corrosion of the pipe at  ;

the water contact location. l 1

For Code Class 3 piping, Generic Letter 90-05 )

identifies two flaw evaluation approaches that should be considcred, the "through-wall flaw" approach and the " wall thinning" approach. Generic Letter 90-05 states that a temporary non-code repair may be proposed if a defect is found acceptable by the "through-wall flaw" approach. CP&L has performed an evaluation of the defect using the "through-wall flaw" approach.

As described in Generic Letter 90-05, the "through-wall flaw" approach evaluates flaw stability using a l linear elastic fracture mechanics methodology.

, Generic Letter 90-05 establishes a methodology for determining the through-wall flaw length "2a" and i states that if the length "2a" exceeds either 3 inches or 15 percent of the length of the pipe circumference, the flaw is not acceptab!c using this approach. CP&L has determined the "2a" for the El-3

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6 defect to be approximately 0.55 inches, which meets this acceptance criterion for the "through-wall flaw" approach.

Generic Letter 90-05 also states that for defect stability, linear elastic fracture mechanics methodology specifies that the stress intensity factor "K" be less than the critical stress intensity factor >

representing the fracture toughness of the material.  !

The generic letter specifies that the value of "K" l should be less than 35 ksi(in)as for ferritic steel and f less than 135 ksi(in)as for austenitic stainless steel.

CP&L has also determined the stress intensity factor  !

"K" to be approximately 31.991 ksida)as, which is j less than the applicable acceptance criterion of 35 ksi(in)a5 ,

During the next scheduled outage exceeding 30 days )

duration, but no later than Refueling Outage 13 for )

BSEP, Unit 1, CP&L will perform a repair, in J accordance with ASME Code,Section XI, of the defect in line number 1-SW-110-6-157 between j valve 1-SW-V110 and the 24-inch diameter Conventional Service Water Header. Based on the results of the "through-wall flaw" evaluation, CP&L has concluded that the component is acceptable until Refueling Outage 13 for BSEP, Unit 1, which is currently scheduled to begin on February 26, 2000.

Generic Ixtter 90-05 stipulates that if a defect is l evaluated and found acceptable by one of the two l cvaluation approaches, an augmented inspection J using UT or radiographic examination (i.e., RT) to assess overall degradation of the affected system should be performed. The generic letter indicates ,

that an augmented inspection should be performed within 15 days of detection of the defect, and that the augmented inspection is a part of the relief acceptance criteria of the temporary non-code repair of the Class 3 pipe. Augmented inspections of five susceptible and accessible locations have been completed using the UT method. The results of these examinations were evaluated and found to be acceptable; all findings comply with the original El-4

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j code of construction (i.e., United States of America I Standard (US AS) B31.1, " Power Piping" - 1967).

As stipulated by Genenc Letter 90-05, until the code repair is completed, the integrity of the defect area will be assessed at least every three months using a non-destructive examination technique. In addition, as stipulated by Generic Letter 90-05, a qualitative assessment of leakage through the defect area will t be performed at least every week to identify any degradation of structural integrity until the code repair is completed.

In conclusion, the overall degradation of the l affected portion of the Service Water system has l been assessed and evaluated as acceptable.

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l ENCLOSURE 2 BRUNSWICK STEAM ELECTRIC PLANT, UNIT NO. I NRC DOCKET NO. 50-325/ LICENSE NO. DPR-62 ,

ASME BOILER AND PRESSURE VESSEL CODE, SECTION XI-IN-SERVICE INSPECTION PROGRAM - REQUEST FOR RELIEF TO PERFORM A NON-CODE REPAIR OF SERVICE WATER PIPE List of Regulatory Commitments ,

j The following table identifies those actions committed to by Carolina Power & Light (CP&L) ,

Company in this document. Any other actions discussed in the submittal represent intended or l planned actions by CP&L. They are described for the NRC's information and are not regulatory commitments. Please notify the Manager- Regulatory Affairs at the Brunswick Steam Electric i Plant of any questions regarding this document or any associated regulatory commitments. j 1

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Commitment Committed j date or outage '

l. Assess the integrity of the defect area located on line number At least every l

l-SW-110-6-157 between valve 1-SW-V110 and the 24-inch 3 months until i diameter Conventional Service Water Header (i.e., completion of a line 1-SW-100-24-154),in accordance with Generic code repair.

Ixtter 90-05, using a non-destructive examination technique.

2. Perform a qualitative assessment of leakage through the defect At least every area located on line number 1-SW-110-6-157 between week until l valve 1-SW-VI10 and the 24-inch diameter Conventional completionof a l Service Water Header (i.e., line 1-SW-100-24-154), in code repair.

accordance with Generic Letter 90-05, to identify any degradation of structural integrity.

3. Perform a repair,in accordance with the ASME Code, Next scheduled Section XI, of the defect area of line number 1-SW-110-6-157 outage exceeding between valve 1-SW-VI10 and the 24-inch diameter 30 days duration, Conventional Service Water Header (i.e., but no later than line 1-SW-100-24-154). Refueling Outage Bl13R1.