ML20196K709
| ML20196K709 | |
| Person / Time | |
|---|---|
| Site: | South Texas  |
| Issue date: | 07/02/1999 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML20196K707 | List: |
| References | |
| NUDOCS 9907120011 | |
| Download: ML20196K709 (5) | |
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UNITED STATES
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NUCLEAR REGULATORY COMMISSION e
WASHINGTON, D.C. 20565 0001 o%...../
SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO.100 TO FACILITY OPERATING LICENSE NO. NPF-80 STP NUCLEAR OPERATING COMPANY. ET AL.
SOUTH TEXAS PROJECT. UNIT 2 DOCKET NO. 50-499 l
1.0 INTRODUCTION
l By application dated July 1,1999, STP Nuclear Operating Company (the licensee) requested changes to the South Texas Project, Units 1 and 2, Technical Specifications (TSs) on an emergency basis. The proposed changes would provide for a one time change to TS 3.3.2 and 3.7.8 for Unit 2 to allow all fuel handling building (FHB) exhaust air system components to be inoperable for a period not to exceed 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> to facilitate repair of the Train B exhaust booster fan. The one-time change may be used twice and would be effective only from the date of the amendment until July 14,1999.
2.0 BACKGROUND
TSs 3.7.8 and 3.3.2 (Table 3.3-3, Functional Unit 11) require three independent fuel exhaust booster f,ns and three independent FHB main exhaust fans and actuation instrumentation to be operable. In addition, TS 3.9.12 establishes requirements for FHB exhaust air system during l
movement of fuel. No change to TS 3.9.12 is necessary because the licensee will comply with the applicable action of this TS to not move fuel or operate the crane over the spent fuel pool.
Operability of the FHB exhaust air system ensures that radioactive material leaking from the emergency core cooling equipment within the FHB following a loss-of-coolant accident (LOCA) l and radioactive material release from an accident involving an irradiated assembly in the FHB are filtered prior to reaching the environment.
This occurrence is the first required replacement of exhaust booster fan 21B. Replacement of failed exhaust booster fan 218 will require a temporary modification to isolate the ductwork to the fan from the rest of the system. The process of installing and subsequently removing the temporary modification will require breaching the common exhaust and supply plenums serving the three exhaust booster fans. During the time the plenums are breached, the requirements of TS 3.7 8 for the FHB exhaust air system are not met. In addition, while the temporary modification is being installed and removed, the other exhaust booster fans and the main exhaust fans will be in pull-to-lock for personnel safety. In this condition, the system cannot automatically actuate and the requirements of TS 3.3.2, Table 3.3-3, Functional Unit 11 are not 9907120011 990702 PDR ADOCK 05000499 P
.. met for all trains. Both of these conditions would require that TS 3.0.3 be entered, and shutdown of Unit 2 would be required.
The proposed change would allow all FHB exhaust air system components in Unit 2 to be inoperable for a period not to exceed 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> for installation and not to exceed 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> for removal of the temporary modification to allow repair of the failed exhaust booster fan.
Installation and removal of this temporary modification would be allowed only once by this change and would be limited to a defined time period. The proposed change is required to address the South Texas Project plant design, which incorporates unique, three-train design features. The separate trains of ventilation in the FHB exhaust air system typically use common plenums or ductwork that must be opened to permit maintenance and testing. The proposed changes to the actions for the TSs will permit this maintenance to be conducted without entering TS 3.0.3 (requiring a shutdown of the unit). A permanent modification has been installed in Unit 1 to allow exhaust booster fan repairs without a need to secure the remaining two FHB exhaust ventilation trains. This same permanent modification is scheduled for installation in Unit 2 durinr the fall 1999 refueling outage.
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' 3.0 EVALUATION The safety basis for the staff's evaluation is to avoid an undesliable plant transient as a result of forcing compliance with the TSs for which no compensatory benefit to public health and safety existed. Compensatory measures proposed by the licensee for the time during which all FHB exhaust air system components would be inoperable and considered in the staff's evaluation included (1) stopping the movement of any loads over the spent fuel pool or any loads (as defined in the licensee's heavy loads program) over the emergency core cooling system pumps or suction piping in the FHB; (2) stopping any movement of irradiated fuel assemblies; (3) stopping all activities that could potentially affect spent fuel pool level or cooling; and (4) developing a pre-job briefing and other administrative controls to restore the FHB exhaust system within 16 minutes of an increase in reactor containment building radioactivity that would be an indication of a reactor coolant system leak, an increase in FHB radiation levels, or reactor trip (the FHB exhaust air system filters emergency core cooling system radioactive leakage that occurs during the recirculation phase of accident mitigation; the recirculation phase would not occur prior to 16 minutes after a postulated accident).
. These compensatory measures are determined to be sufficient to provide reasonable
- assurance that there would not be any increase in either onsite and offsite dose consequences following a postulated fuel handling or LOCA and, as such, the proposed TSs are acceptable.
' In addition, a shutdown of Unit 2 to repair FHB exhaust Fan 21B would constitute a potential operational risk.
4.0 EMERGENCY CIRCUMSTANCES The Commission's regulations in 10 CFR 50.91 contain provisions for issuance of amendments
. with less than a 30-day comment period if emergency circumstances are determined to exist.
Emergency situations involved those cases in which failure to act in a timely way results in the derating or shptdown of a nuclear power plant or prevents either resumption of operation or increase in power output up to the plant's licensed power level. Under emergency circumstances, the Commi?sion may issue a license amendment involving no significant
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.. l hazards consideration without prior notice and opportunity for a hearing or for public comment.
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- In such a situation, the Commission publishes a notice of issuance under 10 CFR 2.106, providing for opportunity for a hearing and for public comment after issuance.
For emergency circumstances, the licensee is required to explain the reason " the condition and why it could not be avoided. This requirement is intended to prevent the abuse of the special provisions of 10 CFR 50.91(a)(5).
Unit 1 FHB exhaust booster fan 11B failed in April 1998 and Unit 1.FHB exhaust booster fan 11 A failed in October 1998, in both occurrences, the licensee requested and received enforcement discretion for TS.3.0.3 to support the use of the temporary modification to effect -
repairs. This emergency TS proposalis essentially the same as those previous requests for enforcement discretion. The TS 3.7.8 limiting condition for operation action statement for the FHB exhaust air system was entered at 3:00 a.m. Centre! Daylight Time (CDT) on June 29, 1999, to perform scheduled maintenance. On June 30, W99, a ground was discovered in the
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' FHB exhaust booster fan 21B during a surveillance following system maintenance. The fan was declared inoperable and the action statement of TS 3.7.8 remained in effect, with 7 days to j
restore the fan or be in at least hot standby in the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and cold shutdown in the
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following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />. The 7-day allowed outage time expires at 3:00 a.m. CDT July 6,1999.
Therefore; failure to act on the emergency amendment request in a timely manner will result in shutdown of Unit 2.
Following the 1998 exhaust booster fan failures, the licensee has made good faith attempts to alleviate a need for further licensing actions in the event of another exhaust booster fan failure, as discussed below. A TS amendment request was developed and submitted to the staff in September 1998 to allow, in part, for a 12-hour allowed outage time with all FHB exhaust air system components inoperable. However, the staff has delayed review of that amendment until the generic resolution of this TS is established. Also, a plant modification was developed and implemented during the spring 1999 Unit 1 refueling outage to allow replacement of FHB exhaust booster fan motors without a need to secure the remaining two FHB exhaust ventilation trains. This same modification is planned for implementation during the fall 1999 Unit 2 refueling outage. In addition, the licensee has determined the root cause for fan failures (inadequate insulation design and manufacturing quality) and developed a plan to systematically replace fan motors with upgraded spares while rewinding and restocking the warehouse spares.
Based on the above considerations, the staff concludes that the licensee has not abused the emergency provisions by failing to make a timely application for the amendment and that there are emergency circumstances present that warrant issuance of the amendment pursuant to 10 CFR 50.91(a)(5).
5.0 FINAL NO SIGNIFICANT HAZARDS CONSIDERATION
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' The Commission's regulations in 10 CFR 50.92(c) state that the Commission may make a final determination that a license amendment involves no significant hazards consideration if operation of the facility in accordance with the amendment would not:
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(1)
Involve a significant increase in the probability or consequences of an accident previously evaluated; or l
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C (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.
Operation of the facility in accordance with the proposed amendment will not involve a significant increase in the probability or consequences of an accident previously evaluated.
The fuel handling accident will be precluded from occurring by ensuring that no loads will be carried over the spent fuel pool and no movement of irradiated fuel will take place during the time that repairs are being made. Regarding the large-break LOCA, the FHB exhaust air system is not identified as a precursor to a design-basis event, and therefore, does change the probability of that accident. Regarding the consequences of an accident, administrative controls will be in place to restore the FHB exhaust system within 16 minutes of an increase in reactor containment building radioactivity that would be an indication of a reactor coolant system leak, increase in FHB radiation levels, or a reactor trip. The 16 minutes prior to radioactive emergency core cooling leakage occurring is adequate time to secure the work, ensure that the plenum integrity is restored and the FHB main and exhaust booster fans are started or placed in automatic, and for the workers to exit the FHB. The low likelihood of a design basis accident during the limited period of allowed inoperability of this system coupled with compensatory actions that will be simple, straightforward, and well briefed prior to starting this evolution will not result in a significant increase in the consequences of an accident.
Operation of the facility in accordance with the proposed amendment will not create the possibility of a new or different kind of accident from any accident previously evaluated. The J
proposed changes do not involve any new equipment and does not significantly alter the way in l
. which existing equipment is operated.
Operation of the facility in accordance with the proposed amendment will not involve a significant reduction in a margin of safety. The margin of safety can be defined by the ability of the FHB exhaust air system to limit the release of radioactive materials and limit exposures to operators following a postulated accident. The only part of the proposed change that can have an effect on a margin of safety is the proposed allowance for all trains of the FHB exhaust air system to be inoperable for a limited period of time. However, the compensatory measures will restore the system prior to the time it is required to remove contaminants during a postulated accident. Therefore, the proposed changes will not significantly affect the ability to place and maintain the recctor in a safe shutdown condition and will not significantly affect the limiting of the release of any radioactive material.
Based on the above considerations, the staff concludes that the amendment meets the three criteria of 10 CFR 50.92. Therefore, the staff has made a final determination that the proposed j
amendment does not involve a significant hazards consideration.
6.0 STATE CONSULTATION
in accordance with the Commission's regulations, the Texas State official was notified of the proposed issuance of the amendments. The State official had no comments.
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7.0 ENVIRONMENTAL CONSIDERATION
The amendment changes a requirement with respect to the installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20. The NRC staff has determined that the amendments involve no significant increase in the amounts and no 1
significant change in the types of any effluents that may be released offsite, and that there is no significant increase in individual or cumulative occupational radiation exposure. The Commission has made a final finding that the amendment involves no significant hazards consideration. 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 envircnmental assessment need be prepared in connection with the issuance of the amendment.
8.0 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 j
operation in the proposed manner, (2) such activities will be conducted in compliance with the Commission's regulations, and (3) 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: T. Alexion j
Date: July 2, 1999
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