ML20149F791
| ML20149F791 | |
| Person / Time | |
|---|---|
| Site: | Wolf Creek  |
| Issue date: | 07/11/1997 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML20149E866 | List: |
| References | |
| NUDOCS 9707220303 | |
| Download: ML20149F791 (4) | |
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NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20066 4 001 j
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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO.107 TO FACILITY OPERATING LICENSE NO. NPF-42 WOLF CREEK NUCLEAR OPERATING CORPORATION WOLF CREEK GENERATING STATION DOCKET NO. 50-482
1.0 INTRODUCTION
By letter dated April 23, 1997, Wolf Creek Nuclear Operating Corporation (the licensee) requested changes to the Technical Specifications (Appendix A to Facility Operating License No. NPF-42) for the Wolf Creek Generating Station.
The proposed changes would revise Technical Specification 3/4.9.4 to add a new limiting condition of operation to state that Penetration P-63 (service air valves KA V-039 and KA V-118) and Penetration P-98 (breathing air valves KB V-001 and KB V-002) may be opened under administrative controls during core alterations and movement of irradiated fuel assemblies within the containment.
The associated Bases will also be revised.
Specifically, a new LC0 3.9.4.d. would be added as follows:
"d. Penetration P-63 (Service Air valves KA V-039 and KA V-118) and Penetration P-98 (Breathing Air valves KB V-001 and KB V-002) may be opened under administrative controls."
Bases 3/4.9.4 would be changed to read as follows:
"Both containment personnel airlock doors may be open during movement of irradiated fuel or CORE ALTERATIONS, provided on airlock door is capable of being closed and the water level in the refueling pool is maintained as required. Service Air valves KA V-039 and KA V-118 (Containment enetration P-63) and Breathing Air valves KB V-001 and KB V-002 p(Containment penetration P-98) may be opened under administrative controls during movement of irradiated fuel or CORE ALTERATIONS to provide air services to the reactor building to uopport outage activities.
Administrative controls ensure that 1) appropriate personnel are aware of the open status of the containment during movement of irradiated fuel or CORE ALTERATIONS, 2) specified individuals are designated and readily available to close the air 13ck or the service air and breathing air valves following an evacuation that would occur in the event of a fuel handling accident, and 3) any obstructions (e.g., cables and hoses) that could prevent rapid closure of an open airlock can be quickly removed."
NOTE:
Italics indicates the changes.
9707220303 970711 PDR ADOCK 05000482 P
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2.0 MCKGROUND During plant outages, service air and breathing air must be provided to the containment building to support various outage activities.
The requirements for containment penetration closure ensures that a release of fission products within the containment will be restricted from escaping to the environment.
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Allowing penetration flow paths that provide direct access from the containment atmosphere to the outside atmos)here to be opened under administrative control raises the concern tlat radioactivity could be released through the unisolated flow paths in the event of an accident during core alterations or movement of radioactive fuel that leads to a release of radioactivity.
Normally. Penetration P-63 (a nominal 4-inch line) and P-98 (a nominal 2-inch line) would not provide direct access from the contLinment atmosphere to the ot.tside atmosphere because of the pressurization of the service air and breathing air lines from their respective air compressors when the systems are in service.
However, the possibility exists that direct i
. access could be established through these penetrations if tho associated air compressor was turned off or failed with its respective containment isolation valves open.
The licensee has proposed to use administrative controls, currently in place for the open containment air lock, to ensure the manual valves are closed whenever t1eir associated air compressors are not running.
In the event of a fuel handling accident or loss of cooling, the manual isolation valves would be closed.
3.0 EVALUATION The licensee has ioentified two accidents that could result in a release of radioactive material through the two potential leak paths:
a fuel handling accident that results in breaching of the fuel rod cladding, and a loss of residual heat removal (RHR) cooling event that could lead to core boiling and uncovery.
Amendment 95 approved leaving the containment air lock open during fuel movement and core alterations.
In that application, the licensee recalculated the doses and revised the design basis for the fuel handling accident analysis to be consistent with Regulatory Guide (RG) 1.25. "Assum)tions Used for Evaluating the Potential Radiological Consequences of a uel Handling Accident r
in the Fuel Handling and Storage Facility for Boiling and Pressurized Water Reactors."
In that reanalysis, credit was not taken for the containment tailding barriers. The licensee's analysis calculated the doses for the 0-2 hour period at the exclusion area boundary to be 0.2 rem to the whole body and 55 rem to the thyroid. These calculated doses are within the standard review
-plan (SRP) criteria of 6 rem to the whole body and 75 rem to the thyroid.
The thyroid dose to the control room operators was calculated to be 9.7 rem and is within the exposure guidelines of General Design Criterion (GDC) 19.
The NRC staff did an independent analysis of the fuel handling accident in its evaluation of Amendment 95 to determine conformance with the requirements of 10 CFR Part 100 and GDC 19. The staff analysis utilized the accident source term given in RG 1.4. " Assumptions Used for Evaluating the Potential Radiological Consequences of a loss of Coolant Accident for Pressurized Water
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4 Reactors." the assumptions contained in RG 1.25 and the review procedures specified in SRP Sections 15.7.4 and 6.4.
The staff assumed an instantaneous i
i suff release of nobel gases and radioiodine from the gap and plenum of the aroken fuel rods.
These gas bubbles will pass through at least 23 feet of water covering the fuel prior to reaching the conteinment atmosphere.
All airborne activity reaching the containment atmosphere is assumed to exhaust to the environment within 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />. Thegapactivityisassumedtohavedecayed for a period of 100 hours0.00116 days <br />0.0278 hours <br />1.653439e-4 weeks <br />3.805e-5 months <br />.
The staff s analysis calculated the doses for the 0-2 hour period at the exclusion area boundary to be 0.14 rem to the whole body and 39.7 rem to the thyroid.
The dose to the operators was calculated to be 0.07 rem to the whole body and 14.5 rem to the thyroid.
These doses are within the SRP guidelines and the GDC 19 guidelines.
The potential dose consequences from a simultaneous release of the gaseous effluents through the unisolated penetration flow paths and the open personnel airlock doors is the same. That is because the analysis assumes all radioactive material from the fuel handling accident is released to the environment.
Therefore, allowing penetration flow paths to be unisolated
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during core alterations or movement of irradiated fuel will not invalidate the l
conclusion that the potential dose consequences from a fuel handling accident will be well within the 10 CFR Part 100 limits. The staff agrees with this conclusion.
The licensee has reported for the case where RHR cooling is lost, the release of radioactive material would be insignificant as a result of boil-off, provided the event does not continue for an extended period of time, which could result in core uncovery and core damage.
This is because the amount of radioactivity is limited to the total coolant activity.
Maximum coolant activity is limited to that activity that corresponds to 1 percent fuel defect.
This activity is less than the total gap activity assumed to be released from a fuel handling accident. The time to boil in the core 100 hours0.00116 days <br />0.0278 hours <br />1.653439e-4 weeks <br />3.805e-5 months <br /> after shutdown is greater than 5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> if a loss of RHR cooling should occur.
Technical Specification 3/4.9.8 requires that corrective actions be taken immediately to restore RHR cooling and that all containment penetrations that are open to the outside atmosphere be closed within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />.
The licensee concludes that if cooling is restored within the 5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />, the release of radioactivity from the reactor core through an unisolated penetration would not be a concern.
The staff agrees with this conclusion.
I The staff has historically required plant technical s)ecifications to maintain containment closure during core alterations and fuel landling as a defense-in-depth measure to further limit releases. This has been relaxed by allowing both doors to the containment air lock to be o>en during core alterations and fuel handling with provisions in place to quictly close one door (Amendment 1
195, dated February 28. 1996).
The licensee has proposed to extend the same provisions to the two open containment penetrations which are: written procedures that require designated personnel to be informed of the open status of the valves in question and specified persons to be designated and readily
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i available to isolate the open penetration in the event of a fuel handling accident.
These conditions are described in the revised Bases Section 3/4.9,4.
i The staff has' reviewed the licensee's analysis and its own analysis performed in conjunction with Amendment 95.
The staff concludes that the radiological
~ consequences associated with the fuel handling accident with both containment air lock doors open bounds the case where the two containment penetrations are open.. Therefore, the proposed change to allow containment Penetration P-63 and Penetration P-98 to remain open during core alterations or irradiated fuel movement within the containment, with administrative controls in place to quickly close them, is acceptable.
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4.0 STATE CONSULTATION
In accordance with the Commission's regulations, the Kansas State Official was notified of the proposed issuance of the amendment.
The State official had no comments.
5.0 ENVIRONMENTAL CONSIDERATION
The amendment changes a requirement with respect to installation or use of a facility component located within the restricted area as defined in 10 _FR Part 20.
The NRC 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 or cumulative occupational radiation exposure. The Commission h6s previously issued a proposed finding that the amendment involves no significant hazards consideration, and there has been no public comment on such finding (62 FR 30648). 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 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 amendment will not be inimical to the common defense and security or to the health and safety of the public.
Principal Contributor:
J. Stone Date:
July 11, 1997
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