ML20214K396

Safety Evaluation Supporting Amend 6 to License NPF-36

ML20214K396
Person / Time
Site:	Shoreham File:Long Island Lighting Company icon.png
Issue date:	05/18/1987
From:	Office of Nuclear Reactor Regulation
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ML20214K333	List: ML20214K331 ML20214K388 ML20214K396
References
NUDOCS 8705280427
Download: ML20214K396 (5)

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+ o, UNITED STATES E*  % NUCLEAR REGULATORY COMMISSION .

WASHING TO N, D. C. 20555 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOP REGULATION ,

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, SUPPORTING AMENDMENT NO. 6 TO FACILITY OPERATING LICENSE NO. NPF-36 LONG ISLAND LIGHTING COMPANY l SHOREHAM NUCLEAR POWER STATION I

DOCKET NO. 50-322 ,

1.0 INTRODUCTION

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By letter dated February 4, 1987 as supplemented by letter dated April 10, i 1987, Long Island Lighting Company (the licensee) reouested an amendment '

to Facility Operating License No. NPF-36 for the Shoreham Nuclear Power .

Station. LILCO letter SNRC-1205, dated October 10, 1985. stated that two-pump injection was the preferred method of compliance with ATWS Rule 10 CFR 50.62(c)(4), subject to the results of a test. The two-pump injection test was performed in September 1986 under cold shutdown conditions; the results of the test showed that two-pump operation would not be viable at Shoreham for compliance with the rule. Hence, another method of compliance was necessary. For Shoreham, Rornn enrichment was chosen.

In Reference 1, the licensee for Shoreham Nuclear Power Station Unit #1, requested changes to the Technical S Standby Liquid Control System (SLCS)pecifications with regard to theThe prop licensee's plan to enrich the boron in the sodium pentaborate in the SLCS tank to eighty-five (85) atom percent Boron-10. This increase in Boron-10 enrichment is proposed to satisfy the reouf rements of 10 CFR 50.62.C.(4).

In Reference 2, the licensen supplemented its request by the addition of  ;

a Surveillance Reouirementi S.R.4.1.5.e., to the proposed chances.  ;

2.0 EVALHATION l LILC0 is participating in the BWR Owner's Group ATWS implementation alternatives program. BWR Owner's Group submitted NEDE-31096-P

" Anticipated Transients without Scram, Response to NPC ATWS Rule, 10 CFR 50.62 " (Ref. 3) for staff review. The staff accepted the licensing topical report NEDE-31096-P in Reference 4 LILC0 selected the third option

, dEnriched Boron Solution" to satisfy the 86 gpm equivalency requirement.

This design alternative maintains the current design of only one-pump operation.

{- In order to satisfy the equivalent control capacity requirements of 10 i

l CFR 50.62, the Shoreham 218 inch (internal diameter) reactor pressure vessel would require a Boron-10 sodium pentaborate enrichment of 1

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• S approximately forty (40) atom percent. As part of the effort to find a suitable alternative to two-pump operation, a study was performed to determine the effect of greater sodium pentaborate enrichment on the magnitude of the ATWS core melt frequency estinate presented in -the- -

Shoreham Probabilistic Risk Assessment which was submitted by letter dated June 24, 1983. The use of higher enrichmert allows additional time for Standby Liquid Control initiation because less time is required for injection of the amount (weight) of sodium pentaborate necessary to achieve a hot shutdown condition. This results in a decrease in the human error probability estimate for Standby Liquid Control System in,iection, and to a lesser extent, a reduction in the ATWS core melt frequency.

LILCO has proposed the use of eighty-five atom percent B-10 enriched *

• sodium pentaborate for Shoreham. At the minimum technical specification required injection flow rate of 41.2 GPM, the time required to bring the reactor to hot shutdown will be reduced. This will allow increased time for operator action and result in a higher probability that the SLC system will be initiated in a timely manner. Additionally, the use of enriched pentaborate does not require substantial modification of the SLC system.

Pump redundancy will be maintained. The SLC tank level instrumentation setpoints are chanaed to accomodate the smaller liould poison volume associated with the use of eighty-five percent enriched pentaborate.

Since the chosen sodium pentaborate enrichment exceeds the requirements of 10CFR50.62, we find that the LILCO proposal is acceptable.

After the Standby Liquid Control System (SLCSI two-pump test yielded higher than anticipated discharge line losses, the derivation of the pump discharge surveillance pressure was reviewed. The actual two-pump test results were used to develop a calculated discharge line pressure drop for one-pump operation fat 43 gpm). The maximum pump discharge pressure (for one-pump operation) is the sum of the discharge line losses plus the maximum vessel injection pressure. These maximum values are assumed to occur during a postulated full power ATWS with MSIV closure. The maximum vessel injection pressure is the sum of the lowest setpoint of Safety Relief Valves (SRVs) (1115 psig) and the pressure due to the head of the water in the reactor vessel. The derivation of the pressure at the SLCS sparger based upon the lowest SRY setpoint and a water filled reactor vessel is acceptable.

As a result of this calculation, the pump discharge surveillance pressure of the system was increased from 1190 psig to 1220 psig. This value is still well below the system design pressure and the relief valve setpnint.

The capability of the relief valve to prevent system overpressure and maintain system integrity remains intact. The margin between the relief valve setpoint and the proposed pump discharge surveillance pressure is sufficient to provide reasonable assurance that flow diversion through the relief valves will not occur and will also be verified during the pump surveillance. Thus, the SLCS pump discharge pressure chance from 1190 psig to 1220 psig is acceptable.

The alloweble range of concentrations of the sodium pontaborate solution was changed from 9.8-13% to 9.8-12%. The upper value of allowed concentration was lowered to reduce the probability of equipment failures caused by pentaborate crystallization. The minimum required solution temperature was also changed from 75"F to 65*F to reflect the lower saturation temperature associated with a maximum concentration of 1?

percent. These changes are acceptable.

As reeuested by the staff, LILCO provided additional information (Ref. 2) regarding monitorinn of the Baron-10 enrichment level. LILCO inforred the staff that appropriate portions of the LILCO Ouality Assurance Program, as described in USAR section 17.2 will be used to ensure that the sodium pentaborate procured for use in the SLCS will have a minimum Boron-10 enrichment of eighty-five aton percent. This is acceptable.

LILCO is planning to buy the enriched sodium pentaborate from a chemical i

vendor, rather than mixing at the plant. Hence LILCO's proposal to i analyze the sodium pentaborate solution sample for Boron enrichment at every refueling outage is acceptable.

The bases to Technical Specification 3/4.1.5 were revised to reflect the proposed changes. The revised bases are acceptable since it adequately explains the beses for the current requirements in the Technical Specifications.

3.0 ENVIRONMENTAL CONSIDERATION

This amendment involves a change to a requirement with respect to the i installation or use of a facility component located within the restricted l

' area as defined in 10 CFR Part P0 and changes to the surveillance requirements. The staff has detennined that the amendment involves no i significant increase in the amounts, and no significant chance in the types, j

of any effluents that may be released offsite and that there is no signifi- l I

cant increase in individual or cumulative occupational radiation exposure.

The Comission has previously issued a proposed finding that this amendment involves no significant hazards consideration and there has been no public l l

coment on such finding. Accordingly, this 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 statenont nor environmental assessment need be prepared in connection with the issuance of this amendment.

4.0 CONCLUSION

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The changes proposed by the Ifeensen have been reviewed by the staff against the requirements of the ATWS rule (10 CFR 50.62), and Generic Letter 85-03 " Clarification of Equivalent Control Capacity for Standby Liquid level Control Systems" dated January 28, 1985. The licensee's j l

proposed increase to 85 atom percent boron enrichment with a minimum sodium pentaborate concentration of 9.8% in conjunction with a flow rate .

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4 of 41.2 ;pm will provide a boron content equivalent in control capacity of 86 gpm of 13 weight percent sodium pentaborate for a 251 inch inside diameter vessel. Actually, the minimum system parameters (41.2 gpm, 9.8%

conctntration of 85 atem percent Baron-10 enrichment) wil! ensure an -

equiphntinjectioncapacitythat is POO% of the ATWS rule reouirement for Shoreham. Notwithstanding the above analysis, which considered the smaller reactor vessel diameter of 218-inches for the Shoreham Station, an alternative analysis can be perforced by not taking credit for the smaller reactor vessel diameter. For that alternative analysis, we find that the proposed system still meets the boror delivery capability reouire-ment of the ATWS Rule and would ensure an equivalent injection capacity that is over 150% of the ATWS Rule fl0 CFR 50.62(c)(4)). This is ir compliance with 10 CFR 50.62 and is therefore acceptable.

l The Technical Specification changes proposed by the licensee in T/S sections 4.1.5.a.2, 4.1.5.b.2, 4.1.5.c 4.1.5.e, Figure 3.1.5-2 and bases section 3/4.1.5 are acceptable because they are consistent with the requirements of 10 CFR 50.62. Furthermoro, we have concluded, based on l 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 preposed manner, and (2) such activities will be conducted in compliance with the Commission's regulations, and issuance of this amendment will not be inimical to the commor defense and security l or to the health and safety of the public.

Principal Contributor: G. Thomas Dated: May 18, 1987 l

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REFERENCES

1. LILCO letter SNRC-1310 from John D. Leonard, Jr. ILILCO) to U.S.NRC, February a, 1987. - - -=

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2. LILCO letter SNRC-1323 from John D. Leonard, Jr. (LILCO) to U.S.NRC, dated April 10, 1987.

3. NEDE-31096-P " Anticipated Transients Without Scram; Response to NRC ATWS Pule 10 CFR 50.62." December 1985.

4 Staff SER on GE Topical Report NEDE-31096-P. Letter from Gus Lainas (NRC) to Terry A. Pickens (BWR Owner's Group 1 dated October 21, 1986. , ,

S. Minutes of BWR Owner's Group informal meetino with NRC to discuss ATWS technical specification bases, Rethesda, MD, April 1,1987.

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