ML20135A750
| ML20135A750 | |
| Person / Time | |
|---|---|
| Site: | Brunswick  |
| Issue date: | 09/03/1985 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20135A748 | List: |
| References | |
| NUDOCS 8509100257 | |
| Download: ML20135A750 (5) | |
Text
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o UNITED STATES
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WASHING TON, D. C. 20555 r
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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION SUPPORTING AMENDMENT NO.116 TO FACILITY LICENSE NO. DPR-62 CAROLINA POWER & LIGHT COMPANY BRUNSWICK STEAM ELECTRIC PLANT, UNIT 2 DOCKET NO. 50-324
1.0 INTRODUCTION
By letter dated August 28, 1985, as supplemented by letter dated August 29, 1985, the Carolina Power and Light Company (CP&L the licensee) requested an emergency change to the limiting conditions for operation (LCO) for Brunswick Steam Electric Plant, Unit 2 as set forth in the Technical Specifications (TS) of Facility Operating License No. DPR-62. The 4
requested change would grant a temporary change to the isolation time for the inboard high pressure coolant injection (HPCI) steam line isolation valve until the next refueling outage or the next outage of sufficient time to repack the valve. The change was verbally authorized on August 29, 1985 until September 4,1985, while this amendment is being processed. The verbal authorization was confinned in our letter dated August 29, 1985.
2.0 DISCUSSION In a letter dated August 28, 1985, CP&L notified the Comission of a steam leak in the drywell of Brunswick, Unit 2 approaching TS leakage limits.
l The major source of the leak has been identified to be degraded valve packing in the HPCI turbine steam inlet line inboard isolation valve (E41-F002). Trouble shooting had revealed that the leak rate can be reduced by almost an order of magnitude by backseating the valve. The licensee exercised one option and closed the outboard valve isolating the HPCI system. The letter requested an exigent TS change. Upon further consideration, the licensee decided that isolating the HPCI system was not the least degraded solution and opened the outboard valve. This made the HPCI system operable, but initiated an 8-hour LCO.
In a follow-up letter, the licensee has requested a one-time change to TS 3.6.3.a.1 which would permit Unit 2 operation to continue until the next refueling outage with the E41-F002 valve in the backseated position. Testing has shown that with the valve backseated the automatic valve closure time to increase beyond the LCO of 50 seconds by less than 4 seconds. The licensee proposes that the LCO be changed from 50 seconds to 55 seconds until the valve can be repacked at the next refueling outage.
8509100257 850903 DR ADOCK 05000324 t
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j 3.0 EVALUATION I
Valve E41-F002 is a containment isolation valve which is intended to automatically isolate the HPCI main steam inlet line inside containment should a break occur in the line. A longer valve closing time could result in a steam release outside containment greater than previously calculated i
- for a HPCI steam line break accident. The licensee has reviewed its steam Ifne break accident analyses to determine the consequences of an additional i
5 seconds in the valve closure time. This review has indicated that taking into account the 55 second isolation time, the total coolant released as
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a result of a break in the NPCI line between the inboard and outboard j
isolation valves would continue to be bounded by the more limiting main steam line break accident. The licensee's analysis indicates that the radiological consequences of a HPCI steam line break with the longer
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isolation valve closure time would continue to remain below limits j
specified in 10 CFR 100 by a t least two orders of magnitude.
i In addition to the above, the licensee has also indicated that precautions have been taken to minimize potential damage to the valve motor during the
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backseating operation. To ensure that the valve motor operator has not been degraded during the stroke testing from the backseated position and final backseating operation, the licensee monitored and controlled motor J
current, and perfonned post-operation checks of the motor winding l
resistance. These testing procedures were discussed with CP&L's test
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engineers. The licensee also confirmed that the outboard isolation valve was in an acceptable operating condition based on a successful surveillance j
during the last refueling outage and satisfactory operation during a j
closing and opening cycle on August 28-29, 1985.
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Based on the licensee's analyses of the steam line break accident, the tests perfonned to measure valve stroke time and check motor performance i
for the E41-F002 valve, and satisfactory operation of the outboard I
isolation valve, as discussed above, we conclude that interim operation until the next scheduled refueling outage with the inboard valve (E41-F002) in the backseated position with a response time LC0 of 55 seconds is acceptable. We note the licensee has committed to repair the E41-F002 1
valve should an outage of sufficient duration occur prior to the next refueling outage.
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1 4.0 EMERGENCY CIRCUMSTANCES i
j On August 28, 1985, CP&L requested an exigent license amendment to increase 4
the isolation time limit of the inboard HPCI steam line isolation valve (E41-F002) from 50 to 55 seconds. This would allow the valve to be
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backseated, thus reducing leakage through the valve packing and avoiding an i
j unnecessary shutdown due to exceeding the 5 gpm TS limit for unidentified i
r.eactor coolant system leakage in the drywell.
i' Early on the morning of August 28, 1985, unidentified leakage in the
. Brunswick Unit 2 drywell increased to 4.46 gpm. At that time, three j
possible courses of action existed.
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. 1.
The leakage could be ignored, thereby risking a forced shutdown by exceeding the TS limit of 5 gpm.
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2.
The E41-F002 valve, earlier identified as a major contributor to drywell leakage, could be backseated, declared inoperable, and the 8-hour LCO requiring plant shutdown with an inoperable primary containment isolation valve entered.
Previous isolation time testing revealed that the valve could not be isolated within the required 50 seconds from the backseated position, thus requiring it to be declared inoperable when backseated.
3.
Rather than enter the 8-hour LCO, the outboard HPCI steam isolation line valve could be isolated, the HPCI system declared inoperable, and a 14-day LCO for an inoperable HPCI system entered.
On August 28, 1985, CP&L determined that the most prudent course of action would be to temporarily isolate the HPCI system while filing an exigent license amendment request which would allow the backseated E41-F002 valve to be declared operable and the HPCI system returned to service. An analysis had previously been performed and the determination made that this amendment would not involve a significant hazards consideration.
Upon further review, CP&L determined that the plant would be maintained in a safer condition if the NPCI system were returned to service. This detemination is based on the fact that the analysis performed indicates that the additional 5 seconds closure time resulting from the backseating of the valve is acceptable and it places the plant in a safer condition to have the HPCI system available in the event of an accident. Based on the plant being in a safer condition, CP&L opened the outboard HPCI steam line isolation valve and declared the HPCI system to be operable. This placed Brunswick Unit 2 in an 8-hour LCO. As required by TS 3.6.3.a.1, the inoperable valve must either be restored to operable status within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> or the affected penetration line isolated within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />, or the unit must be in at least hot shutdown within the next 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />. Accordingly, the licensee requested that the August 28, 1985 submittal be processed as an emergency request.
4.1 No Significant Hazards Consideration Determination The Comission's regulations in 10 CFR 50.92 state that the Commission may make a final determination that a license amendment involves no significant hazards considerations if operation of the facility in accordance with the amendment would not:
(1) Involve a significant increase in the probability or consequences of i
an accident previously evaluated; or (2) Create the possibility of a new or different kind of accident from any accident previously evaluated; or (3)
Involve a significant reduction in a margin of safety.
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. The infomation in Section III above provides the basis for evaluating this license amendment against these criteria. Since the requested operational mode, plant operating conditions, the physical status of the plant, and dose conseqdences of potential accidents are the same as without the requested change, the staff concludes that:
(1) Operation of the facility in accordance with the amendment would not significantly increase the probability or consequences of an accident previously evaluated.
(2) Operation of the facility in accordance with the amendment would not create the possibility of a new or different kind of accident from any accident previously evaluated.
(3) Operation of the facility in accordance with the amendment would not involve a significant reduction in a margin of safety.
Accordingly, we conclude the amendment to Facility Operating License No.
DPR-62, permitting isolation valve E41-F002 to operate with a response time of up to 55 seconds, involves no significant hazards consideration.
4.2 State Consultation In accordance with the Comission's regulations, consultation was held with the State of North Carolina by telephone. The State expressed no j
concern either from the standpoint of safety or of no significant hazards i
consideration detemination, in view of the interim nature of the amendment and the compensatory measures.
5.0 ENVIRONMENTAL CONSIDERATION
S The amendment involves a change in the installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20 and a change in a surveillance requirement. The staff has determined that the amendment involves 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 individual oc cumulative occupational radiation exposure. The Comission has made a final no significant hazards consideration finding with respect to this amendment. Accordingly, the amendment meets 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 assessment need be prepared in connection with the issuance of the amendment.
6.0 CONCLUSION
We have 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 pro)osed ;nanner, and (2) such activities will be conducted in compliance wit 1 the Commission's regulations I
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-and the issuance of the amendment will not be inimical to the common defense and security or to the health and safety of the public.
Principal Contributor: Mark Caruso Dated: September 3,1985
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