ML20128B960
| ML20128B960 | |
| Person / Time | |
|---|---|
| Site: | Hatch  |
| Issue date: | 05/10/1985 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20128B908 | List: |
| References | |
| TAC-57410, TAC-57411, TAC-57415, TAC-57416, NUDOCS 8505280121 | |
| Download: ML20128B960 (1) | |
Text
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NUCLEAR REGULATORY COMMISSION j
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WASHINGTON, D. C. 20555
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- %...*.I SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO RE0 VESTS FOR RELIEF FROM INSERVICE INSPECTION RE0VIREMENTS GEORGIA POWER COMPANY OGLETHORPE POWER CORPORATION MUNICIPAL ELECTRIC AUTHORITY OF GEORGIA CITY OF DALTON, GEORGIA EDWIN I. HATCH NUCLEAR PLANT, UNITS 1 & 2 DOCKETS NOS. 50-321 & 50-366 By letter dated April 4,1985, the licensee requested relief for 16 Main Steam Isolation Valves (MSIVs) from that portion of IWV-3427(b) of the 1980 edition of the ASME Section 71 Code that requires an increased frequency of leakrate testing based on leakrate trending of 6-inch and larger valves. The specific valve identification numbers are 1B21-F022 A, B, C, D and IB21-F028 A, B, C, D (Unit 1); 2B21-F022 A, B, C, D and 2821-F028 A, B, C, D (Unit 2).
The ASME Section XI Code r. quires that Category A valves be leakrate tested at least each 2 years. Tha leak test frequency for valves with 6-inch nominal pipe size and larger is required to be doubled, but scheduled to coincide with a cold shutdown, if valve leakrate trends indicate impending valve failure, as follows:
If a leakage rate exceeds the rate determined by the previous test by an amount that reduces the margin between the previously measured leakrate and +.he maximum permissible rate by 50% or greater..
Technical Specifications for both Hatch units require that the MSIVs be tested on a more frequent basis than required by the ASME Section XI Code.
These 24" air-operated globe valves are tested once per refueling outage by applying pneumatic pressure (28 psig) between the inboard and outboard MSIVs with a maximum allowable leakage of 11.5 standard cubic feet per hour (SCFH) per valve. This allowable leakage is small when compared to other Category A valves. Some leakage may occur through mechanically sound valves because the
-inboard MSIV is reverse tested, which tends to lift the globe from the valve seat, thereby allowing leakage that would not occur during a normal pressurization.
We agree with the licensee's basis and therefore conclude that the relief shou'd be granted as requested. The licensee's current MSIV leakrate testing is sufficient to give reasonable assurance of valve leaktightness. The granting of this relief is authorized by law and 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 requirements were imposed on the facility.
Dated:'
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