ML20205E631
| ML20205E631 | |
| Person / Time | |
|---|---|
| Site: | Surry  |
| Issue date: | 08/12/1986 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20205E636 | List: |
| References | |
| NUDOCS 8608180447 | |
| Download: ML20205E631 (2) | |
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9 Enclosure SAFETY EVALUATION SURRY POWER STATION UNIT 1, DOCKET NUMBER 50-280 REQUEST FOR RELIEF FROM ASME SECTION XI HYDROSTATIC TEST REQUIREMENT FOR VALVE REPLACEMENT,
Introduction This report provides a safety evaluation of a request for relief from a specific hydrostatic testing requirement applicable to a repair on the Surry Unit 1 main steam system piping. The request was submitted by Virginia Electric and Power Company (the licensee) in a letter dated June 6, 1986.
The bases for the requirement from which relief has been requested and for granting)the relief are derived from the Code of Federal Regulations,10 CFR 50.55a(g. The subject regulations specify that inservice examinations and tests be perfomed on nuclear power facilities, such as Surry Unit 1, in accordance with the requirements of Section XI of the ASME Boiler and Pressure Vessel Code (ASME Section XI), 1980 Edition, Winter 1980 Addenda. ASME Section XI provides requirements for hydrostatic testing of piping after repairs or replacements.
10 CFR 50.55a(g)(6)(1) states that the Comission may grant relief from the ASME Section XI requirements when they are detemined impractical for a facility, provided the Comission determines that the granting of the relief is authorized by law, will not endanger life or property or the common defense and security and is otherwise in the public interest giving due consideration to the burden upon the licensee that could result if the require-ments were imposed on the facility. The specific ASME Section XI requirement from which relief has been requested, the relief requested, the basis for the relief request, and the NRC staff's evaluation and conclusions are described below.
ASME Section XI Requirements ASME Section XI requires hydrostatic testing of ASME Class 2 piping following repair or replacement. Subsection IWC-5000 provides criteria for detemining the required test pressure for performing the post repair hydrostatic tests on the piping. For testing the recently replaced ASME Class 2 valve,1-MS-268, in Surry Unit 1 main steam system piping, the IWC-5000 criteria specify a test pressure of 1.25 times system pressure. The system pressure for the piping containing this valve is 1085 psig and, thus, the test pressure is required to be 1356 psig.
Discussion The licensee has requested a relief from hydrostatic testing of one li-inch socket welded drain valve (1-MS-268) Just upstream of the main steam trip valve for the Steam Generator B.
Replacement of this valve is necessary due to the harsh environment which causes errosion/ corrosion on the valve seat surface. The valve's external pressure boundary remains unaffected.
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The hydrostatic test required by ASME Section XI would require including the B Steam Generator and a considerable portion of attached main steam piping within the test boundary as no intermediate isolation exists. The licensee stated that this test is impractical, when compared to the actual integrity assurance gained from the inspection.
The licensee has proposed to conduct an alternative inspection of this valve by performing a surface examination (MT or PT), and a visual (VT-2) examination in conjunction with a system inservice pressure test (IWC-5221) during the start up following the refueling outage.
NRC Staff Evaluation and Conclusions In evaluating the licensee's request, the staff has taken into consideration the location, size and function of the involved piping, the alternate testing proposed by the licensee, and the measures that would be necessary to achieve the full specified test pressure. Based on its evaluation of these factors, the staff finds that the hydrostatic test requirement is impractical for the given situation and that granting of the requested relief is authorized by law, will not endanger life or property or the common defense and that it is otherwise in the public interest. The relief requested is hereby granted.
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