ML20237G423

Safety Evaluation Supporting Amend 5 to License DPR-21

ML20237G423
Person / Time
Site:	Millstone
Issue date:	07/30/1987
From:	Office of Nuclear Reactor Regulation
To:
Shared Package
ML20237G394	List: ML20237G392 ML20237G402 ML20237G423
References
NUDOCS 8708240082
Download: ML20237G423 (3)

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[gMG l'og UNITED STATES

1. g~ o NUCLEAR REGULATORY COMMISSION

$ :r N WASHINGTON, D. C. 20555 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION S'UPPORTING AMENDMENT NO. 5 TO FACILITY OPERATING LICENSE N0. DPR-21 NORTHEASTNUCLEARENERGYCOMPAM MILLSTONE NUCLEAR POWER STATION, UNIT,N0. 1 DOCKET NO. 50-245

1.0 INTRODUCTION

By letter dated May 22, 1987, as supplemented by a letter dated July 6, 1987, Northeast Nuclear Energy Company (NNECO) submitted a request for changes to the Millstone Nuclear Power Station, Unit No.1, technical specifications (TS) with regard to the standby liquid control system (SLCS). The proposed changes reflect NNEC0's plan to enrich the boron (B) in the SLCS sodium pentaborate solution to a minimum of fifty (50) atom percent boron-10 (B-10). The changes are proposed to ensure compliance with 10 CFR 50.62 which requires that all BWRs have a SLCS with a minimum flow capacity equivalent to 86 gpm of 13 weight percent sodium pentaborate solution. The increase in B-10 enrichment is proposed to satisfy an equivalency to this requirement.

2.0 EVALUATION NNECO is a participant in the BWR Owners Group ATWS Implementation Alternatives Committee. The BWR Owners Group submitted NEDE-31096-P,

" Anticipated Transients Without Scram, Response to NRC ATWS Rule, 10 CFR 50.62," for staff review. The staff reviewed that report and by letter dated October 21, 1986, issued a safety evaluation accepting the report (Ref. 4). NNEC0 has proposed using the report's third option,

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

This design maintains the current plant design of only one pump SLCS operation. The use of higher enrichment of B-10 allows additional time for SLCS initiation because less time is required for injection of the amount of sodium pentaborate necessary to achieve a hot shutdown condition.

NNECO has proposed the use of fifty-five atom percent B-10 (minimum TS allowable enrichment is fifty atom percent B-10) for the Millstone Unit 1 SLCS. At the minimum technical specification flow rate of 40 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 SLCS will be initiated in a timely manner. The use of enriched sodium pentaborate does not require substantial modification of the SLCS. Pump redundancy is maintained. The SLCS tank level instruments-tion set points will be changed to accommodate the smaller liquid poison l volume associated with the use of an enriched sodium pentaborate solution.

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i Since the proposed sodium pentaborate enrichment exceeds the requirements

! of 10 CFR 50.62, we find that tne NNEC0 proposal is acceptable.

The allowable concentration range of the sodium pentaborate solution has been changed from a range of 9.5%-to 13.4% to no less than 11%. The minimum-required solution temperature curve in the TS is unchanged. This minimum temperature is required to prevent crystallization of the sodium pentaborate solution. The change to an allowable concentration of no less' than 11% sodium pentaborate is acceptable.

In a* letter dated July 6, 1987, NNEC0 stated that for the minimum specified pump flow rate of 40 gpm, minimum specified concentration of 11% using 55% B-10 enriched sodium pentaborate would result in an equivalent injection capacity that is 109% of the ATWS rule requirement for the generic 251 inch diameter reactor vessel. The Millstone Unit No. I reactor vessel has a diameter of 224 inches. Because of the smaller reactor vessel, the proposed SLCS change would result in an equivalent injection capacity that is 140% of the ATWS rule requirement. The staff finds that the proposed system meets the boron delivery capability requirements of the ATWS rule and would ensure an equivalent injection capacity that is greater than required by the ATWS rule. This is in compliance with 10 CFR 50.62 and is, therefore, acceptable.

The enriched sodium pentaborate will be purchased from a vendor. NNECO's proposal to analyze the B-10 enrichment at every reiaeling outage or within 60 days of adding sodium pentaborate to the SLCS tank is acceptable.

The bases to Technical Specification 3.4 were revised to reflect the proposed changes. The revised bases are acceptable since they adequately explain the bases for current requirements in the TS.

3.0 ENVIRONMENTAL CONSIDERATION

This amendment involves a change to a requirement with respect to the installation or use of facility components located within the restricted  ;

area as defined in 10 CFR Part 20 and changes to the surveillance  !

requirements. The staff has determined that the amendment involves no j significant increase in the amounts, and no significant change in the types, j 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 no significant hazards consideration and there has been no public comment on such finding. Accordingly, this amendment meets the eligibility criteria for categorical exclusion set forth in 10CFR51.22(c)(9). Pursuant to 10 CFR 51.22(b) no environmental impact i statement'or environmental assessment need be prepared in connection with j the issuance of this amendment.

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4.0 CONCLUSION

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3 9 The changes proposed by NNEC0 hav1 been reviewed by the Otsff agatast the

< requirement 9;.of the ATWS rule (10 CFR 50.62) and Generic letter 85-03,

" Clarification of Equivalent Control Capacity for Standby Liquid Level

' ControlSfstms,"datedJar,uary 28, 1985.- The minimum sys(em parameters (40 gpm,11% concentration of 50 stom percent / B.M ewfShed sodium

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pentaborate solution) will ensu"o that the control capacity is greater than or equal to the ATWS rule requirement. This is 4n compliance with r

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10 CFR,50.62 and is, therefore, acceptable. , ,

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9' .The TS changes proposed by NNECO are acceptable because $he),Wr consistent with the requirements of 10 CFR 50.62. Furthennore, we Mye toncluded, based on the considerations . disc'gsad above, that (1) therej1s rrspr(ble assurance Ltbat the health and rafet}'of"ti.e publivwill not be mt4ngdttst by operation

~ intthe proposed r.mnner, and'(2) such activitiev will l9 conducted in compliance '1

'with the Commission's' regulations rad the issuance of th H amendment will nct c be in!mical tc the comon defense and securitp'or to the health and safety of-the public. -

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Princip1 Iontributer: M. L. Boyle 1 -

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,. Dated: July 30, 1987 <c l-

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