ML20045C389

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Requests NRC Approval of ISI Program Relief Request B-12 for Units 2 & 3,requesting Relief from Performing Hydrostatic Test at 1.25 Times Lowest SG Rv Pressure Setting for Repair of 4 Inch Unisolable Welds
ML20045C389
Person / Time
Site: San Onofre  Southern California Edison icon.png
Issue date: 06/16/1993
From: Marsh W
SOUTHERN CALIFORNIA EDISON CO.
To:
NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
NUDOCS 9306230049
Download: ML20045C389 (10)
v • d • e


Text

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,. # mWP g 'g,w Southem Califomia Edison Company 23 PAFtKER STREET tRVINE. CALIFORNIA 92718 June 16, 1993 WALTEH C MARSH Tta t'Pucts AS$3SI ANT MANAGE R C/14b 4S4 4403 FtUCL E An NF Gut A T OH f AFF AJFW U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, D.C. 20555 Gentlemen:

Subject:

Docket Nos. 50-361 and 50-362 First Ten-Year Interval Inservice Inspection Program San Onofre Nuclear Generating Station Units 2 and 3 This letter requests NRC approval of Inservice Inspection (ISI) program Relief Request (RR) B-12 for San Onofre Units 2 and 3 (Enclosures 1 and 2, respectively). RR B-12 requests relief from performing a hydrostatic test at 1.25 times the lowest steam generator relief valve pressure setting (Psv) as required by ASME Section XI, Articles IWA 4400 and IWC-5222(a) for repair or replacement of Class 2 piping. This relief request applies to portions of piping to be added by Minor Modification Package (MMP) #2&3-6869-00SM that cannot be isolated from the steam generator by existing valves.

In lieu of the hydrostatic test, the following will be performed on the unisolable welds:

1) A VT-2 examination will be performed at Mode 3 pressure and temperature conditions (Mode 3 steam pressure is nominally 100 to 150 psi higher than full load steam pressure), and
2) Surface examinations will be performed using the methods in Section XI, IWA-2230 and 1WA-2220 in addition to any required volumetric examinations specified by the repair and replacement articles in IWA-4000 and IWA-7000.

Background / Basis for Relief The steam supply lines to the Auxiliary Feedwater (AFW) Pump turbine for both Units 2 and 3 will be modified during the upcoming Cycle 7 outages. The purpose of the modification is to minimize the accumulation of condensate in the AFW Pump Turbine steam supply system. The modification will involve re-routing the take-off point of the AFW steam supply line from the main steam safety valve header drain line to the top of the safety valve header.

Drawings of the two header lines affected by this modification are attached to the relief request for each unit as Figures 1 and 2.

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' Document Control Desk Following this work, the Code normally requires a hydrostatic test at 1.25  !

times Psv. However, the steam generators are not isolable from portions of 'i the replaced piping, and they would also be subjected to the hydrostatic test at 1.25 times Psv. The pressure Psv is the lowest pressure setting of the safety or relief valves provided for over-pressure protection within the boundary of the system to be tested.

Hydrostatic testing of the steam generators at 1357 Psig (1.25 times Psv) during plant shutdown conditions would require both a test temperature greater than 120 F to meet the fracture prevention-criteria of the steam generator and isolation of the safety relief valves. The Code required hydrostatic test is not in our current outage plan. We believe this hydrostatic test does not-provide measurable benefit over the alternative testing proposed by Relief.

Request B-12 to justify the cost of performing the hydrostatic test and .

increasing the outage duration by several days.  ;

The alternative testing was discussed with the NRC staff in a telephone conversation on June 2, 1993 and the staff suggested we formally submit a relief request. We request NRC approval by August 1, 1993, to ensure Un't 2 can be returned to service as scheduled on August 21, 1993.

If you have any questions regarding these relief requests, please let me know.

Very truly yours, h0h Enclosures cc: B. H. Faulkenberry, Regional Administrator, NRC Region V ,

C. W. Caldwell, NRC Senior Resident Inspector, San Onofre Units 1, 2&3 M. B. Fields, NRC Project Manager, San Onofre Units 2 and 3

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4 RELIEF REQUEST B-12 Unit 2, Docket 50-361 Page 1 of 2 SYSTEM: Steam Generator / Main Steam COMPONENT / AREA: 4" line welds in the line from the main steam header to the auxiliary feedwater pump which are unisolable from the steam generator.

EXAMINATION CATEGORY: IWC-5222(a)

CLASS: 2 FUNCTION: Maintain integrity of a high pressure steam system.

EXAMINATION REQUIREMENT: The system hydrostatic test shall be at least 1.1 times the system pressure Psv for systems with Design Temperature of 200 F (93 C) or less, and at least 1.25 times the system pressure Psv for systems with Design i Temperature above 200 F (93 C). The system 3ressure Psv shall be the lowest pressure setting among tie number of safety or' relief valves provided for overpressure -

  • protection within the boundary of the system to be tested.

BASIS FOR RELIEF: MMP # 2&3-6869.00SM will modify the main steam piping to the Auxiliary Feedwater Pump Turbine during the upcoming Cycle 7 outages in both Units 2 and 3. This '

modification, which involves welding connections to the main steam piping and can not be isolated from the steam generator, will require hydrostatic testing of the modified Class 2 piping under the ASME Section XI program.

The modification will be installed and the majority of welds hydrostatically tested to 1.25 times system design pressure in accordance with the ASME Code. (The system design pressure is substituted for Psv for systems not provided with safety valves.) There are 9 welds which can not be hydrostatically tested without  :

hydrostatically testing the steam generators.

Figures 1 and Figure 2 are provided to show the two lines added by this modification. The figures indicate '

the 9 welds which are subject to this relief request, all other welds will be hydrostatically tested to 1.25 times Psv.

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RELIEF REQUEST B-12 Unit 2, Docket 50-361  !

Page 2-of 2 To. pressurize the steam generator and the associated piping to 1.25 times Psv is not desirable due to the following reasons:

1) The test would need to be performed during plant  ;

heat up and would require the safety valves, which are normally set during the outage, to.be gagged for this hydrostatic test. The Code required hydrostatic test is not in our current outage plan. We believe this hydrostatic test does not provide measurable benefit. over the alternative testing proposed by Relief Request B-12 to justify the cost of aerforming the hydrostatic test and 't increasing tie outage duration by several days.

2) The ASME Committees are currently reviewing the possibility of relaxing hydrostatic testing requirements following repair or replacement 4 activities. This relaxation trend can be seen in Code Cases N-498, N-416, and the currently-proposed revision to Code Case N-416 (416-1).

ALTERNATE i EXAMINATION PROCESS: In lieu of the hydrostatic test the following will be performed:

1) A VT-2 examination will be performed at Mode 3 pressure and temperature conditions (Mode 3 steam pressure is nominally 100 to 150 psi higher than full load steam pressure), and
2) The welds that will not receive the ASME Section XI hydrostatic test will be examined by surface examinations using the examination methods in Articles IWA-2220 and IWA-2230 in addition to any required volumetric examinations specified by the repair and replacement articles in Section XI, IWA-4000 and IWA-7000.

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RELIEF REQUEST B-12 Unit 3, Docket 50-362 Page 1 of 2 SYSTEM: Steam Generator / Main Steam COMPONENT / AREA: 4" line welds in the line from the main steam header to the auxiliary feedwater pump which are unisolable from the steam generator.

EXAMINATION CATEGORY: IWC-5222(a)

CLASS: 2 FUNCTION: Maintain integrity of a high pressure steam system.

EXAMINATION REQUIREMENT: The system hydrostatic test shall be at least 1.1 times the system pressure Psv for systems with Design Temperature of 200 F (93 C) or less, and at least 1.25 times the system pressure Psv for systems with Design Temperature above 200 F (93 C). The system pressure Psv shall be the lowest pressure setting among the number of safety or relief valves provided for overpressure protection within the boundary of the system to be tested.

BASIS FOR RELIEF: MMP # 2&3-6869.00SM will modify the main steam piping to the Auxiliary Feedwater Pump Turbine during the upcoming _

Cycle 7 outages in both Units 2 and 3. This modification, which involves welding connections to the main steam piping and can not be isolated from the steam generator, will require hydrostatic testing of the modified Class 2 piping under the ASME Section XI program.

The modification will be installed and the majority of welds hydrostatically tested to 1.25 times system design pressure in accordance with the ASME Code. (The system design pressure is substituted for Psv for systems not provided with safety valves.) There are 9 welds which can not be hydrostatically tested without hydrostatically testing the steam generators.

Figures 1 and Figure 2 are provided to show the two lines added by this modification. The figures indicate the 9 welds which are subject to this relief request, all other welds will be hydrostatically tested to 1.25 times Psv.

RELIEF REQUEST B-12 Unit 3, Docket 50-362 Page 2 of 2 To pressurize the steam generator and the associated piping to 1.25 times Psv is not desirable due to the following reasons:

1) The test would need to be performed during plant heat up and would require the safety valves, which are normally set during the outage, to be gagged for this hydrostatic test. The Code required hydrostatic test is not in our current outage plan. We believe this hydrostatic test does not provide measurable benefit over the alternative testing proposed by Relief Request B-12 to justify the cost of performing the hydrostatic test and increasing the outage duration by several days.
2) The ASME Committees are currently reviewing the possibility of relaxing hydrostatic testing requirements following repair or replacement activities. This relaxation trend can be seen in Code Cases proposed revision N-498, N-416, to Code and Case the (416-1 N-416 currently ).

ALTERNATE EXAMINATION PROCESS: In lieu of the hydrostatic test the following will be performed:

1) A VT-2 examination will be performed at Mode 3 pressure and temperature conditions, (Mode 3 steam pressure is nominally 100 to 150 psi higher than full load steam pressure), and
2) The welds that will not receive the ASME Section XI hydrostatic test will be examined by surface examinations using the examination methods in Articles IWA-2220 and IWA-2230 in addition to any required volumetric examinations specified by the repair and replacement articles in Section XI, IWA-4000 and IWA-7000.

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