ML20216C134
| ML20216C134 | |
| Person / Time | |
|---|---|
| Site: | Byron  |
| Issue date: | 05/08/1998 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML20216C122 | List: |
| References | |
| NUDOCS 9805190109 | |
| Download: ML20216C134 (3) | |
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UNITED STATES g
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NUCLEAR REGULATCHY COMMISSION 2
WASHINGTON, D.C. 20066 0001
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FAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION EgtATED TO AMENDMENT NO.102 TO FACILITY OPERATING LICENSE NO. NPF 37 AND AMENDMENT NO.102 TO FACILITY OPERATING LICENSE NO. NPF-86 COMMONWEALTH EDISON COMPANY BYRON STATION. UNIT NOS.1 AND 2 DOCKET NOS. STN 50-454 AND STN 50-455
1.0 INTRODUCTION
By letter dated November 7,1997, as supplemented on IWarch 24,1998, and April 9,1998, Commonwealth Edison Company (Comed), the licensee for Byron Station, Units 1 and 2, requested a deferral of the next seneduled Type A containment integrated leak rate test for Byron, Unit 2, until the next refueling outage in 1999. A consideration in this request is the failure of one of two previous Type A tests. The staff has reviewed the licensee's submittal and our evaluation is provided below. The April 9,1998, supplement provided clarifying information which did not change the staff's initial proposed no significant hazards consideration.
2.0 BACKGROUND
The Byron, Unit 2, technical specifications (TS) require that containment leakage rate testing shall be performed in accordance with Option B of 10 CFR Part 50, Appendix J, and Regulatory Guide (RG) 1.163, Performance-Based Containment Leak Test Program", September 1995.
Among other things, RG 1.163 specifies that periodic Type A (integrated leakage rate tests) of the containment shall be performed at a frequency of at least every 48 months. RG 1.163 also i
allows an extension of this test interval by 15 months.
The first Byron, Unit 2, Type A test following a successful pre-operational test was conducted in September 1990. This test was a failure due to leakage by a steam generator manway. The second Byron, Unit 2, Type A test was successfully conducted in September 1993. In accordance with Option B, another Type A test must be performed by December 1998. This date includes the 15 month extension. The licensee has proposed to defer performance of this Type A test until the next refueling outage, B2R08, in 1999 which would mean an extension of the test interval by approximately 10 months. Because the extension of the test interval included in Option B has already been credited, the licensee has proposed a change to the Byron, Unit 2, TSs to permit an exception to RG 1.163 to defer the Type A test.
Because of the past problem with failure of a Type A test due to steam generator manway leakage, the review of this deferral request concentrated on this potential leak.8 path.
9805190109 980500 PDR ADOCK 05000454 P
2-3.0 EVALUATION Steam generator secondary manways provide access to the interior of the steam generators so that various inspections and operations (such as sludga lancing) can be performed. Thus, they are removed regularly during outages. The design of the manway provides for bolting from the outside so that the steam generator secondary side pressure during normal operation is acting in the direction to force the manway open. The licensee's March 24,1998, submittal states, however, that 4
"... the [manway] gasket load is 8.6% higher during accident conditions and Type A testing than during normal plant operation."
1 That is, the manway gasket is compressed more (making a tighter seat) during accident conditions and. Type A testing (which simulates containment accident pressure), than during normal operation when the pressure is in the opposite direction and the bolts provide the only
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compressive force on the gasket. Thus, it is reasonable to assume that a manway leaking during normal operation would be a conservative indication of the potential for leakage during accident conditions when containment integrity is important. Prior to the failed Type A test in September 1990, there was a steam leak in the steam generator manway, as described in the licensee's
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March 24,1998, submittal.
As discussed in the March 24,1998, submittal, the licensee has equipment and procedures in place for detecting and evaluating steam generator manw.sy leakage. While these procedures do not require shutdown if a manway leaks, long-terr i operation with a leaking manway would be deleterious to the steam generator structure in the vicinity of the leak and, thus, would not be a desirable condition to continue.
The March 24,1998, submittal states that walkdowns will be performed "as the unit approaches normal operating parameters" with the steam generator pressurized to approximately 1000 psig which will include inspections for manway leakage.
The staff considers it acceptable to defer performance of the scheduled Type A test for 10 months. This is based on licensee surveillances which will be performed during startup and the design of the steam generator manway which makes it likely that steam leakage through the manway will be a precursor to a condition which would result in failure of a Type A test. Such leakage is detectable and the licensee states that procedures are in place to evaluate such leakage.
4.0 STATE CONSULTATION
in accordance with the Commission's regulations, the Illinois State official was notified of the proposed issuance of the amendments. The State official had no comments.
5.0 ENVIRONMENTAL CONSIDERATION
The amendments change surveillance requirements. The NRC staff has determined that the amendments involve no significant increase in the amounts, and no significant change in the types, of any effluents that may be released offsite, and that there is no significant increase in
3-individual or cumulative occupational radiation exposure. The Commission has previously issued a proposed finding that the amendments involve no significant hazards consideration, and there has been no public comment on such finding (63 FR 17036) Accordingly, the amendments meet the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9). Pursuant to 10 CFR 51.22(b), no environmental impact statement or environmental assessrnent need be prepared in connection with the issuance of the amendments.
6.0 CONCLUSION
The Commission has concluded, based on the considerations discussed above, that: (1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, (2) such activities will be conducted in compliance with the Commission's regulations, and (3) the issuance of the amendments will not be inimical to the common defense and security or to the health and safety of the public.
Principal Contributor: Richard Lobel Date: May 8, 1998 4
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