ML14183A403
| ML14183A403 | |
| Person / Time | |
|---|---|
| Site: | Robinson  |
| Issue date: | 06/04/1999 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML14183A402 | List: |
| References | |
| NUDOCS 9906090222 | |
| Download: ML14183A403 (7) | |
Text
RE0 UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 b /
SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION ULTIMATE HEAT SINK TECHNICAL SPECIFICATION H. B. ROBINSON, UNIT 2 DOCKET NO. 50-261
1.0 INTRODUCTION
By letter dated April 12, 1999, Carolina Power & Light Company (CP&L or the licensee) requested a temporary change to the Technical Specifications (TS) for the H. B. Robinson Steam Electric Plant, Unit 2, in accordance with 10 CFR 50.90. Specifically, the licensee proposed to revise TS 3.7.8, "Ultimate Heat Sink (UHS)" to provide a new Required Action and Completion Time for the UHS in the event that service water (SW) temperature exceeds the design limit of 95 degrees Fahrenheit (OF). The proposed new Action would require restoring the SW temperature to within the design limit with a Completion Time of 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />.
2.0 BACKGROUND
During the summer of 1998, in anticipation of the UHS temperature exceeding 950F, the licensee had requested an identical change to TS 3.7.8 by a letter dated June 26, 1998, as supplemented by their letter dated July 22, 1998. This would have allowed plant operation above 950 F for up to 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />, and the purpose of the change was to reduce the risk associated with plant shutdown transients. The TS change at that time was supported by an engineering evaluation, which concluded that the components that rely on the SW System (SWS) for cooling are able to operate at a SW temperature of up to 990F. The request proposed a similar change to TS 3.7.8 with an upper temperature limit of 990F and, as a long-term resolution for this condition, committed to perform an engineering analysis to justify an increase in the allowed SW temperature by May 1999. The staff then issued a Notice of Enforcement discretion followed by exigent license amendment no. 179 to TS 3.7.8 by a letter dated July 29, 1998, allowing such a request to exceed the UHS temperature for 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> and limited the effective period of the change to last through the summer months, until September 30,.1998. The service water, however, did not exceed the temperature and the amendment expired on September 30, 1998.
Since the summer of 1998, CP&L has further evaluated the capability of components cooled by the SWS to perform their intended function in much more detail (see details below) but has not been able to completely evaluate all issues to support a final revision to the UHS temperature prior to the summer of 1999. Hence, the licensee submitted this request for temporary change to TS 3.7.8 to be in effect until September 30, 1999, by which time the licensee will be able to complete the analysis supporting a permanent revision.
The UHS provides a heat sink for the operating and decay heat produced by various plant components during normal operation, transients, and accidents. The SWS and the Component Cooling Water (CCW) System are used to transfer heat from plant components to the UHS.
9906090222 990604 PDR ADOCK 05000261 PDR
-2 The UHS at Robinson is defined as the Lake Robinson Impoundment, including necessary retaining structures, and the canals or conduits connecting the sources with, but not including, the cooling water intake structures. The UHS temperature is a function of insolation, operation of H. B. Robinson, Units 1 (fossil) and 2 (nuclear), hydrology of the Lake Robinson watershed, and meteorological conditions which affect the efficiency of evaporative cooling, natural convection, and diurnal radiant heat losses. During the summer, the average heat input due to insolation is comparable to the total heat input from both Robinson Units 1 and 2. Condensing cooling water and SW discharged from the plant are returned to greater Lake Robinson via a 4.2 mile-long discharge canal, which terminates in the lake near its upper end (SWS intake is at the lower end of the lake). During full power operation, the normal transient time of water through the discharge canal is approximately 3.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />. Hence, the effect of a plant shutdown in the event that the SWS temperature limit is exceeded will not immediately be effective on the temperature of the SW entering the plant. However, in the summer months during periods of hot weather, a diurnal effect of alternating insolation of the lake water during the day and increased radiant and evaporative heat loss during the night results in a variation of lake water temperature around a 24-hour cycle.
The current TS 3.7.8 specifies the following Actions and Completion Times for the UHS inoperable for any reason, including SWS temperature >950F:
C.1 Be in Mode 3 within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />, AND C.2 Be in Mode 5 within 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />.
The current TS contains three conditions. Conditions A and B apply to a previous one-time amendment. Conditions A and B were in effect until September 30, 1998, and Condition C came into effect after September 30, 1998. The proposed change restores Conditions A and B to be in effect until September 30, 1999.
The licensee proposed to retain the requirements of C.1 and C.2 as B.1 and B.2 for the new specified Condition B which would be applicable if the Required Actions and Completion Times of Condition A are not met OR the UHS is inoperable for reasons other than Condition A (for example, low water level). The new Condition A would specify the following Actions and Completion Times with SW temperature >950F:
A.1 Restore service water temperature to 95.F within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />, AND A.2 Verify service water temperature is 99.F every 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />.
Therefore, if the SW temperature was not restored to within limits within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />, the UHS would essentially be considered inoperable and B.1 and B.2 would apply (same Actions and Completion Times as current TS).
Additionally, a NOTE has been added to the Actions section which states that Conditions A and B shall not apply after September 30, 1999, at which time the current Condition C will apply.
-3 3.0 EVALUATION The SWS temperature is an input to the containment analysis contained in Final Safety Analysis Report (FSAR) Section 6.2. The SWS temperature is also a design assumption for the spent fuel pool cooling system (SFPCS), auxiliary feedwater (AFW) system, CCW system and its loads, the emergency diesel generators (EDGs), containment air recirculation cooling (CARC) system, room coolers for certain safety-related areas, and non-safety-related systems. Where components rely upon SWS temperature to maintain the components within operating temperature limits, the licensee's evaluation determined that the components could withstand SW temperatures up to 990F.
Since the summer of 1998, CP&L has further evaluated the capability of components cooled by the SWS to perform their intended function. Some components, such as the EDGs, Containment Air Recirculation System Fan Coolers, Steam Driven Auxiliary Feedwater Pump, and CCW System (including Spent Fuel Pool Cooling), were specifically reevaluated because of the complex effect of operation at a higher SW temperature. In addition, the ability to achieve cold shutdown following a fire and a Station Blackout were evaluated at a higher SW temperature. These calculations and evaluations show that these components are fully capable of performing their intended safety function up to a SW temperature of 990F. The capability of the Containment Air Recirculation Fan Coolers to remove heat from the containment following a main steamline break (MSLB) inside containment or a loss-of-coolant accident (LOCA) inside containment could not be evaluated in detail without reanalyzing these events at the higher SW temperature. Therefore, CP&L is reanalyzing the containment response to an MSLB inside containment and a Large Break LOCA inside containment. As committed to in previous correspondence, CP&L will submit a proposed change to the TS, that justifies plant operation at a higher SW temperature for an unlimited period of time when these analyses.are completed.
Permanent UHS Temperature Revision -The containment analyses use the SWS temperature of 950F as a limiting input parameter. Therefore, it is appropriate to limit the amount of time that SWS temperature may be above the 950F limit. Since the probability that a design basis accident (DBA) would occur during this time period is low, and the expected temperature increase above the limit is small, the proposed change is of low safety significance.
To assure that the safety significance remains low, the licensee, in its July 22, 1998, submittal, revised the proposed change to include an upper limit of 990F to further ensure that component temperature limits will not be exceeded following a DBA. All of these justifications were considered in the staffs position conveyed previously through the safety evaluation dated July 29, 1998, and are still valid until the issues related to containment cooling are resolved as a part of the permanent revision the licensee is expected to complete by May 1999.
8-hour AOT -Also, in support of a permanent change for an 8-hour AOT for the UHS, the licensee submitted a separate request via their submittal dated March 26, 1999, citing other "similar" AOTs for the refueling water storage tank (RWST) and containment air temperature.
The staffs position conveyed previously through the safety evaluation dated July 29, 1998, was that similarities among RWST and containment air specification limits did not warrant permanent changes to UHS action or completion times. The staff concludes that this position is still valid.
Also, a generic change to the Standard TS as proposed by the licensee and approved by the Improved TS Task Force of the Westinghouse Owners' Group (WOG) for a generic revision to
-4 NUREG-1431 is currently under staff review for adoption as a permanent AOT. The licensee has volunteered to be the lead plant to work with the WOG to provide additional information to resolve staff comments as discussed above.
The review and approval of such a permanent change either via the owner's group or the NRC staff for a temperature revision to the UHS for a plant-specific change is expected to take some length of time. In order to avoid transients associated with plant derating in the event of any unusually hot and dry weather that the licensee might encounter this summer, the staff concludes that a temporary amendment as requested should be allowed. The 8-hour Completion Time of Action A.1 for being slightly above the design basis temperature is acceptable on a temporary basis because the cooled equipment has been analyzed and found to remain within the manufacturer's limits in the event of an accident and the probability of a DBA occurring during the 8-hour period is small. While the permanent AOT is being pursued through the WOG, the staff finds that there is adequate technical justification to accept the proposed changes to TS 3.7.8 on a temporary basis through September 30, 1999.
The staff also concludes that the proposed modifying Note is acceptable because it is necessary to reflect the temporary aspects of the proposed TS change.
4.0 STATE CONSULTATION
In accordance with the Commission's regulations, the State of South Carolina official was notified of the proposed issuance of the amendment. The State official had no comments.
5.0 ENVIRONMENTAL CONSIDERATION
This 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. 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 has previously issued a proposed finding that the amendment involves no significant hazards consideration, and there has been no public comment on such finding (64 FR 24193). 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 this amendment.
6.0 CONCLUSION
As a result of its evaluation as described above, the staff concludes that the proposed change to TS 3.7.8 provides a significant amount of additional flexibility without any significant reduction in plant safety because of its temporary nature and supporting analysis regarding the cooled equipment. The proposed change is, therefore, acceptable.
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
-5 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: Ram Subbaratnam Date:
June 4, 1999
H. B. Robinson Steam Electric Carolina Power & Light Company Plant, Unit No. 2 cc:
Mr. William D. Johnson Mr. Mel Fry, Acting Director Vice President and Corporate Secretary N.C. Department of Environment, Carolina Power & Light Company Health and Natural Resources Post Office Box 1551 Division of Radiation Protection 3825 Barrett Dr.
Raleigh, North Carolina 27609-7721 Ms. Karen E. Long Assistant Attorney General Mr. Robert P. Gruber State of North Carolina Executive Director Post Office Box 629 Public Staff - NCUC Raleigh, North Carolina 27602 Post Office Box 29520 Raleigh, North Carolina 27626-0520 U.S. Nuclear Regulatory Commission Resident Inspector's Office Mr. Virgil R. Autry, Director H. B. Robinson Steam Electric Plant South Carolina Department of Health 2112 Old Camden Road Bureau of Land & Waste Management Hartsville, South Carolina 29550 Division of Radioactive Waste Management 2600 Bull Street Columbia, South Carolina 29201 Mr. Terry C. Morton Manager Performance Evaluation and Mr. J. W. Moyer Regulatory Affairs Director of Site Operations Carolina Power & Light Company Carolina Power & Light Company 412 S. Wilmington Street H. B. Robinson Steam Electric Plant Raleigh, North Carolina 27601 Unit No. 2 3581 West Entrance Road Mr. John H. O'Neill, Jr.
Hartsville, South Carolina 29550 Shaw, Pittman, Potts & Trowbridge 2300 N Street, NW.
Public Service Commission Washington, DC 20037-1128 State of South Carolina Post Office Drawer 11649 Columbia, South Carolina 29211 Mr. R. L. Warden Manager - Regulatory Affairs Mr. H. K. Chemoff Carolina Power & Light Company Supervisor, Licensing/Regulatory Programs H. B. Robinson Steam Electric Plant, Carolina Power & Light Company Unit No. 2 H. B. Robinson Steam Electric Plant, 3581 West Entrance Road Unit No. 2 Hartsville, South Carolina 29550-0790 3581 West Entrance Road Hartsville, South Carolina 29550 Mr. D. E. Young, Site Vice President Carolina Power & Light Company H. B. Robinson Steam Electric Plant, Unit No. 2 3581 West Entrance Road Hartsville, South Carolina 29550
AMENDMENT NO. 183 TO FACILITY OPERATING LICENSE NO. DPR H. B. Robinson, UNIT 2 DISTRIBUTION:
[D~ky t File PUBLIC PDII Reading File J. Zwolinski/S. Black OGC G. Hubbard, SPLB/DSSA J. Luehman, TSB/DRIP S. Peterson J. Tatum, SPLB/DSSA G. Hill (4)
R. Subbaratnam ACRS OPA OC/LFDCB B. Bonser, RII cc: H.B. Robinson 2 Service List