ML18153C503
| ML18153C503 | |
| Person / Time | |
|---|---|
| Site: | Surry  |
| Issue date: | 01/23/1991 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML18153C502 | List: |
| References | |
| NUDOCS 9101240307 | |
| Download: ML18153C503 (3) | |
Text
UNITED STATES
- NUCLEAR REGULATORY COMMISSION WASHINGTON, D. C. 20555
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10 CFR 50.55a(g) requires examinations and tests of nuclear power facility piping and components be performed in accordance with the requirements of the applicable ASME Section XI Code edition and addenda.
If it is impractical to meet a requirement, the licensee of the facility is required to notify the Coimrfssion and submit infonnation in support of the determination that a requirement is impractical to perform.
This information is evaluated by the CoRlllission and, upon making the necessary findings, the Coimrfssion may grant relief from the requirement giving due consideration to the burden upon the licensee that could result if the requirement were imposed on the facility.
By letter dated December 10, 1990, Virginia Electric and Power Company (the licensee) submitted to the NRC a request for relief from the hydrostatic test requirements of the 1980 Edition, Winter 1980 Addenda of Section XI of the ASME Code for a welded replacement valve in the Auxiliary Feedwater System at Surry Power Station, Unit 1.
The information provided by the licensee is evaluated herein pursuant to 10 CFR 50.55a to determine if the necessary findings can be made to grant the request.
REQUfSl"--ANll--SUP-P{)RTING.-WORMAT-ION-A. RELIEF REQUESTED Relief is requested from the hydrostatic test pressure requirement of the 1980 Edition, Winter 1980 Addenda of Section XI of the ASME Code for the weld on the inlet side of Class 3 check valve 1-FW-142.
B. SECTION XI CODE REQUIREMENT A component repair or replacement shall be pressure tested as required by IWA-4400 and IWA-7000 prior to resumption of service. The test pressure and temperature, subsequent to component repair, shall conform with the system test pressure and temperature specified in IWD-5000.
Where a repaired or replaced component is isolable within a portion cf the system, only that portion need be pressure tested.
The system hydrostatic test pressure shall be at least 1.25 times the system pres-sure, Psv, for systems with design temperature above 200°F.
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.
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- The system test temperature during a system hydrostatic test in syst~ms con-structed of ferritic steel components shall satisfy either the requirements of fracture prevention criteria, as applicable, or the test temperature detennined by the owner.
C. LICENSEE'S BASIS FOR REQUESTING RELIEF The licensee stated that during hydrostatic testing of recently completed modifications on the Auxiliary Feedwater System, excessive internal back leakage was identified at check valve 1-FW-142.
To eliminate this back leakage, the decision was made to replace the six-inch discharge check valve for steam-driven auxiliary feedwater pump l-FW-P-2.
Paragraph IWA-5214 of ASME Section XI requires that a hydrostatic test be performed with a corresponding VT-2 examination on,the affected area. As no intermtdiate isolation exists and because the discharge piping is welded directly to the pump, the required test on the upstream weld would include 1-FW-P-2 (steam-driven auxiliary feedwater pump) and the associated suction piping within the hydrostatic test boundary. This would result in overpres-surization of these components to meet the test requirements (IWD-5223 test pressure:
1576 psig, suction piping design pressure is 30 psig).
Section/Paragraph IWA-5224(d) of ASME Section XI allows the use of the pressure rating for the*suction piping out to the first discharge shut-off valve in the case of centrifugal pumps during hydrostatic tests. Use of this Code paragraph in the application would eliminate the need for this relief request as test pressure would only be 33 psig for the replaced welds.
Code committee personnel have indicated that this is a Code oversight and that future Code editions will change the requirements for high pressure multi-stage centrifugal pumps.
As such, it is the licensee's position that a relief request is necessary.
D. LICENSEE'S PROPOSED ALTERNATIVES Alternatively, it is proposed that a volumetric examination and a surface examination be performed on the new upstream weld in lieu of the hydrostatic test. In addition, a system functional test (IWD-5222) and its corresponding VT-2 examination will be conducted with the normal Technical Specification required operability test for auxiliary feedwater pump 1-FW-P-42.
EVALUATION The information submitted by the licensee included IS! Classification Boundary Drawing No. 11448-CBM-068A, REV. 5, that shows the location of the replaced valve (1-FW-142) in the discharge piping of the steam-driven auxiliary feedwater pump l-FW-P-2.
From the drawing, the low pressure suction piping to the pump cannot be isolated from the higher pressure discharge piping in which the weld required to be subjected to the hydrostatic test pressure of 1576 psig is located. It is therefore impractical to meet the hydrostatic test pressure requirements of Section XI in this situation without major modifications to the
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- discharge piping of the pump.
Imposition of the requirement on the licensee would cause a burden that would not be compensated by the increase in plant safety over that provided by the licensee's proposed alternative. The volumetric and surface examinations of the weld wi11 provide sufficient information to assess its structural integrity.
GGNtb.lJSJQN-Based on the above evaluation, the staff concludes that, pursuant to 10 CFR 50.55a(g)(6)(i), the relief from the hydrostatic test may be granted as requested.
The staff has determined that this relief is authorized by law and will not endanger life or property or the coll'ITlon defense and security and is otherwise in the public interest.
In granting this relief, the staff has given due consideration to the burden that could result if the requirements were imposed on the facility.
Dated: January 23, 1991 Pf!iAt~ --CentJ!-ibut-e-r-:
G. Jonson I
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