ML17187A611
| ML17187A611 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 10/08/1996 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML17187A609 | List: |
| References | |
| NUDOCS 9610100280 | |
| Download: ML17187A611 (3) | |
Text
y UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO THE INSERVICE TESTING PROGRAM RELIEF REQUEST COMMONWEALTH EDISON COMPANY DRESDEN NUCLEAR POWER STATION. UNIT 3 DOCKET NO. 50-249
1.0 INTRODUCTION
The Code of Federal Regulations~ 10 CFR 50.55a, requires that inservice testing (IST) of certain American Society of Mechanical Engineers (ASME)
Boiler and Pressure Vessel Code (Code) Class 1, 2, and 3 pumps and valves be performed in accordance with Section XI of the ASME Code and applicable addenda, except where relief has been requested and granted or proposed alternatives have been authorized by the Commission pursuant to 10 CFR 50.55a(f)(6)(i), (a)(J)(i), or (a)(J)(ii).
In order to obtain rel'ief, the applicant must demonstrate that: (1) conformance is impractical for its facility; (2) the proposed alternative provides an acceptable level of quality.
and safety; or (3) compliance would result in a hardship or unusual difficulty without a compensating increase in the level of quality and safety.
2.0 BACKGROUND
By letter dated September 5, 1996, Commonwealth Edison Company (ComEd, the licensee) submitted a one-time request for relief from certain ASME Code IST requirements pertaining to the frequency of testing of several safety valves and a safety/relief.valve in the plant main steam system for Dresden, Unit 3.
The plant IST program requires that the testing meet the requirements of the 1986 Edition of Section XI of the ASME Code, Subsection IWV-3511, which references the ANS)/ASME Operations and Mainten~nce (OM) Standard, OM-1-1981 (herein referred to as OM-I).
Specifically, this request seeks a one-time
- relief from performing the next periodic tests before the dates which would be required by OM-I.
The following is a list of the plant safety and safety/relief valves for which the licensee is seeking this one~time relief:
VALVE ID 3-0203-3A 3-0203-4A 3-0203-4B 3-0203-4C 3-0203-4D 3-0203-4E DESCRIPTION Main Steam Target Rock Safety/Relief Valve Main Steam Safety Valve n
ENCLOSURE I
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3-0203-4F 3-0203-46 3-0203-4H n n
For the above described valves, the licensee is requesting one-time relief from the following testing requirements:
OM-1, paragraph 1.3.3.1.2 3.0 BASIS FOR RELIEF All valves of each type and manufacture shall be tested within each subsequent 5-year period with a minimum of 20 percent of the valves tested within any 24 months.
The current Dresden Technical Specification (TS) Surveillance Requirement (SR) 4.6.E requires that a minimum of I/2 of *all main steam safety valves (MSSV) and the safety/relief valve. (S/RV) shall be bench checked or rep.laced with bench-checked valves each refueling outage.
For purposes of meeting the above OM-I requirement, MSSVs 3-0203-4A through 4H are of the same type and manufacturer, but S/RV 3-0203-3A is not. Therefore, the MSSVs are grouped together, and the S/RV is in a group by itself.
In order to meet TS SR 4.6.E, the Target Rock S/RV and I/2 of the previously untested MSSVs are tested or replaced each refueling outage. Since* the bresden operating cycles are usually I8 months long, the frequency of testing for these valves is usually more restrictive than the OM-I required frequency.
However, the duration of the last two Unit 3 refueling outages (D3RI2 and D3RI3) were significantly longer than usual.
The licensee states that the D3RI4 refueling outage was scheduled to begin September 7, I996, but that it has been delayed due to the unforeseen duration of forced outages since the last refueling o~tage. The licensee currently expects to begin D3RI4 in the spring of I997.
To meet the above OM-I requirement that all valves in a test group be tested within a 5-year period, MSSVs 3-0203-4E, 4F, 4G, and 4H would have to be tested by October 8, I996, since these valves were last tested on October 8, I991.
MSSVs 3-0203-*4A, 48, 4C, and 4D were last tested on June I3, I994, and S/RV 3-0203-3A was last tested on June 24, I996.
To meet the OM-I requirement to test 20 percent of the valves in each group within any 24 months, two MSSVs would have to be tested by December I3, I996, and the S/RV would have to be tested by December 24, I996 (applying a 25 percent extension provided by the plant TS for surveillance.)
The licensee is requesting relief from the above OM-I test frequency requirements, stating that the tests would result in hardship without a compensating increase in quality or safety. The licensee states that the removal and replacement of the valves for testing prior to the next refueling outage (D3RI4) would require an estimated 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> per valve.* Also, it would result in additional radiation exposure to personnel of one man-rem per valve.
A related OM-I requirement states that, when a partial complement of pretested valves is installed, all valves which were removed must be tested prior to
- plant startup. This could also result in additional time delay in returning the plant to power operation.
The licensee proposes that, instead of testing to meet the above frequency requirements of OM-I, MSSVs 3-0203-4E, 4F, 4G, 4H and S/RV 3-0203-3A be tested and replaced with pretested valves during the upcoming refueling outage (D3RI4).
This would require a one-time schedular relief from the 5-year and 24-month test intervals for the MSSV valve group and from the 24-month test interval for the qne S/RV group.
4.0 EVALUATION The staff agrees with the licensee that performing the MSSV and S/RV testing to meet the above schedular requirements of OM-I would result in unusual hardship without a compensating increase in quality or safety as described.
The proposed period of additional time, beyond the dates these valves would be required to be tested to meet OM-I until the next outage in the spring of I997, is relatively short. Based on a review of the licensee's operating experience with these valves and general industry experience with similar valves, significant additional degradation of these components would not be expected during this additional period. Therefore, the staff agrees that it is acceptable to perform the testing of these valves, as proposed by the licensee, during the next Unit 3 refueling outage.
5.0 CONCLUSION
Based on the above evaluation, the staff has determined, in accordance with IO CFR 50.55a(a)(3)(ii), to authorize the licensee's proposed alternative to the above discussed ASME Code testing requirements since compliance with these requirements would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety.
Principal Contributor:
G. Hammer, NRR/DE Date: October 8, 1996