ML20235E528

Safety Evaluation Supporting Amend 55 to License DPR-34

ML20235E528
Person / Time
Site:	Fort Saint Vrain
Issue date:	06/29/1987
From:	Office of Nuclear Reactor Regulation
To:
Shared Package
ML20235E511	List: ML20235E510 ML20235E520 ML20235E528
References
TAC-63576, NUDOCS 8707110099
Download: ML20235E528 (4)

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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION SUPPORTING AMENDMENT NO. 55 TO FACILITY OPERATING LICENSE NO. OPR-34 i

PUBLIC SERVICE COMPANY OF COLORADO FORT ST. VRAIN NUCLEAR GENERATING STATION DOCKET NO. 50-267

1.0 INTRODUCTION AND BACKGROUND

By letter dated January 15, 1987 (P-87002), the licensee requested changes to the Fort St. Vrain (FSV) technical specifications eliminat-

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ing reliance on the reheater sections of the steam generators for j

Safe Shutdown Cooling.

This request resulted from events reported by the licensee in Licensee Event Reports (LER's) dated August 11, 1986 (P-86513) and October 17, 1986 (P-86587).

In these LER's, the licensee reported that the reheater sections of the steam generators could only support Safe Shutdown Cooling at greatly reduced power levels.

l There were also limitations on the economizer-evaporator-superheater j

(EES) section, but these were less severe.

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By letter dated January 15, 1987, the licensee submitted proposed changes to the Fort St. Vrain (FSV) Technical Specifications to require both EES sections and both reheater sections be available during operation at power as the minimum number of operable heat exchangers.

The FSV Technical Specifications currently require both the reheater section and the EES section of one steam generator and either the reheater section or the EES section of the other steam generator be operable for the removal of decay heat.

The licensee stated that each EES section provides adequate capability for Safe Shutdown Cool-ing from power levels in excess of 82 percent.

However, a reheater section does not provide adequate capability for Safe Shutdown Cooling at power levels above 39 percent, and therefore the licensee will no longer rely on reheaters for Safe Shutdown Cooling from any power level. The licensee proposed to change the Basis for LCO 4.3.1 to state that the reheater sections are capable of providing cooling for other abnormal events, but are not relied upon to provide Safe Shut-down Cooling.

The licensee also proposed a second LCO change which stated that the EES sections shall be capable of receiving water from both the Emergency Condensate Header and the Emergency Feedwater Header during power operation, instead of the former minimum allowable of only one of these emergency headers.

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. t Although the EES sections can be supplied water from both the Emer-gency Condensate Header and the Emergency Feedwater Header, only one of the two headers is needed to supply the required cooling water i

I for Safe Shutdown Cooling.

The reheaters can be supplied with water from the Emergency Condensate Header, but not from the Emergency

(

Feedwater Header.

I The licensee stated these LC0 changes are desirable due to the limita-tions of a reheater section to adequately support Safe Shutdown Cooling with firewater following a ninety-minute Interruption of Force Circu-j lation (10FC).

The licensee submitted a Safety Analysis which demon-

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strates that reliance on the EES sections for Safe Shutdown Cooling meets all of the regulatory requirements for emergency cooling.

The licensee also submitted detailed analyses to the NRC to justify operation using an EES section for Safe Shutdown Cooling at power I

levels in excess of 82 percent reactor power.

These analyses also confirm the adequacy of shutdown cooling using FSV's limiting 10 CFR Part 50, Appendix R, Fire Protection cooling water flow path from approximately 82 percent reactor power.

The licensee has determined that a reheater section cannot support 4

Safe Shutdown Cooling from power levels above approximately 39% power.

Since the proposed changes to LC0 4.3.1 only eliminate reliance on the reheaters for Safe Shutdown Cooling, these changes do not affect the consequences for other accidents.

By requiring both reheaters and both EES sections to be operable, the proposed changes increase the likelihood that the necessary heat exchangers would be available when called upon to provide cooling for other accidents and abnormal events.

The licensee has also submitted by letter dated February 6, 1987 (P-87053), confirmatory analyses of these other accidents and abnormal events previously evaluated in the FSAR which do not involve Safe Shutdown Cooling.

The licensee stated that these analyses demonstrate that the steam generators can provide adequate core cooling for the other FSAR accidents.

By letter dated June 24, 1987 (P-87236), the licensee noted that exist-ing temperature measurement of the steam generator outlet temperature would be supplemented by local thermometers at appropriate locations in the plant.

2.0 EVALUATION This evaluation only concerns itself with the proposed technical specification change, and does not constitute approval of plant operation at a higher power level.

Thus, the effective date of this amendment is when the staff approves operation of FSV at a power level above 35 percent of full power.

This change concerns itself with the availability of a sufficient number of steam generator heat exchangers and water sources to assure Safe Shutdown Cooling can be accomplished.

These changes j

modify the current plant Technical Specifications so that both EES sections are available, and two water sources are available.

The licensee has evaluated this modified system for a variety of l

initiating accidents, including:

High Energy Line Breaks Seismic Events, and Tornadoes.

These evaluations have shown the adequacy of the system in terms of the number of heat exchangers and water sources.

The key point in this change is that the Safe Shutdown Ccoling flow is now through the EES portions of the two steam generators.

Specifi-cally, the licensee analyzed the changes to the flow paths to show that there was a fully redundant flow path available.

He performed a single failure analysis which showed that the Safe Shutdown Cooling system would function with an active single failure, and could withstand a passive single failure after the first 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

Furthermore, the licensee has stated that equipment used in the Safe Shutdown Cooling paths is environmentally qualified.

The licensee's program for equip-f ment qualification was approved by the NRC in a letter dated April 13, 1987.

The pumps and the power supplies for the pumps and other equipment involved remain unchanged.

Hence, no new evaluation of these compo-nents is required.

The Safe Shutdown Cooling process is monitored and controlled by observing the outlet temperature of the steam i

generator.

This temperature is monitored by Category 2 qualified equipment as described in the licensee's submittals concerning Regulatory Guide (RG) 1.97.

R.G. 1.97 provides guidance for plant variables to be used in emergency response facilities, including the control room.

By letter dated April 22, 1987, the staff found this instrumentation acceptable to meet the requirements of R.G. 1.97.

Additionally, to assure highly accurate measurement of this parameter, the licensee will place local thermometers in instrument wells at appro-priate locations in the plant.

The additional instruments, and their calibration will be under plant administrative controls.

Furthermore, the licensee evaluated these changes against the requirements for decay heat removal by the auxiliary feedwater system of a PWR as stated in the Standard Review Plan, Section 10.4.9, Subsection III.2, and General Design Criteria 38, 41, 42, 43, 44, and 46.

The licensee found these changes acceptable by these criteria.

i l 1 In view of the limited nature of this change, the information provided, and a review of the licensee's analysis against accepted regulatory criteria, the staff finds these proposed changes to the Safe Shutdown Cooling flow paths are acceptable.

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3.0 ENVIRONMENTAL CONSIDERATION

l The amendment involves a change in the installation or use of a facil-ity component located within the restricted area. The staff has l

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 this amendment involves I

-no significant hazards consideration and there has been no public comment on such finding.

Accordingly, this amendment meets the eligi-bility criteria for categorical exclusion set forth in l

10 CFR SSI.22(c)(9).

Pursuant to 10 CFR 651.22(b), no environmental j

impact statement or environmental assessment need be prepared in connection with the issuance of this amendment.

4.0 CONCLUSION

The staff 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, and (2) such activities will be conducted in compliance with the Commission's regulations and the issuance of this amendment will not be inimical to the common defense and security or to the health and safety of the public.

Dated:

June 29, 1987 Principal Contributor:

Kenneth L. Heitner, PD-IV l