ML17158A235
| ML17158A235 | |
| Person / Time | |
|---|---|
| Site: | Susquehanna  |
| Issue date: | 04/20/1994 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML17158A233 | List: |
| References | |
| NUDOCS 9404250040 | |
| Download: ML17158A235 (2) | |
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UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, O.C. 2055&4001 ENCLOSURE SAFETY EVALUATION BY THE OFFICE OF. NUCLEAR REACTOR REGULATION RE VEST FOR RELIEF FROM ASME COD HYDROSTATIC TESTING RE UIREMENTS SUS UEHANNA STEAM ELECTRIC STATION UNIT 2 DOCKET NO. 50-388
1.0 BACKGROUND
By letter dated March 24,
- 1994, Pennsylvania Power and Light Company (PP8IL),
the licensee, requested relief from the hydrostatic testing requirements of the ASME Code in connection with the replacement of two drain valves on the "B" loop of the reactor recirculation system of Susquehanna, Unit 2.
The licensee proposed to perform surface examinations of the fillet weld areas and a system leakage test at normal operating pressure in lieu of the Code required hydrostatic test.
The licensee contended that performance of the Code hydrostatic test would constitute an undue hardship without a consequent increase in reliability or safety.
The subject valves are ASME Code Class 1, unisolable primary pressure boundary
They are made from SA-182, grade F-316L, a forged stainless steel.
2.0 DISCUSSION 2.1 Code Requirement ASME Code Section XI, 1980 Edition incorporating Winter 1981 Addenda, subparagraph IWA-4400(a), Pressure
- Test, states that "(after)...repairs (or replacements) by welding on the pressure retaining boundary, a system hydrostatic test shall be performed in accordance with IWA-5000."
2.2 Hardship of Performing Hydrostatic Test For the two drain valves of the reactor recirculation system to be replaced, a
localized hydrostatic test could be performed but this would encompass the reactor recirculation pump seal.
Based upon similar industry events, it is believed that the integrity of the me'chanical seals will be compromised and it will require an unscheduled seal replacement.
A freeze'eal was considered but cannot be executed due to the existing pipe configuration.
The other alternative provided by the Code is a system hydrostatic test.
Although this, only represents a
10% increase in pressure (1035 vs.
1138 psig) a significant number of alterations to plant systems must be performed to 9404250040- 940420 1
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This would place the reactor in an off-normal condition, alter plant systems, and challenge the operators ability to safely operate the Unit.
Alterations to plant systems include:
Disabling nuclear instrumentation required for safety system actuation Gagging safety relief valves Disabling significant portions of the vessel over-pressurization protection 2.3 Alternative Provisions The licensee proposed alternative provisions to be executed in lieu of the Code hydrostatic test.
These consisted of:
1)
Perform pre and post weld surface examinations (liquid dye penetrant) in accordance with the original construction Code (ASHE Section III, 1971 Edition including Addenda through Winter of 1972).
2)
Pre-service inspection (baseline) of the replacement welds shall be performed in accordance with ASNE Section XI, 1980 Edition through ~
Winter of 1981 Addenda.
3)
Prior to return to service, a VT-2 visual examination shall be performed in conjunction with a system leakage test at normal operating pressure in accordance with the pressure-temperature curves in Technical Specification 3.4.6. 1 (IWB-5221).
N.O
~CONC I I The staff finds that imposition of the Code required hydrostatic test would result in a hardship and would not, in this case, result in a commensurate or significant increase in the level of quality or safety of the welds for the subject valves.
Thus, in accordance with 10 CFR 50.55a(a)(3)(ii),
the proposed alternative to the Code hydrostatic test requirements for the replacement of the two. reactor recirculation system valves identified as 243F051B and 243F052B at Susquehanna Unit 2 is authorized.
Principal Contributor:
G. Hornseth N
Date:
Apri 1 20, 1994