ML20198E057

Safety Evaluation Supporting Amend 221 to License DPR-65

ML20198E057
Person / Time
Site:	Millstone
Issue date:	12/17/1998
From:	NRC (Affiliation Not Assigned)
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Shared Package
ML20198E051	List: ML20198E046 ML20198E057
References
NUDOCS 9812230328
Download: ML20198E057 (3)

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j NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 30e664001

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g Q**4Wl SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION I

RELATED TO AMENDMENT NO. 221 TO FACILITY OPERATING LICENSE NO. DPR-65

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NORTHEAST NUCLEAR ENERGY COMPANY THE CONNECTICUT LIGHT AND POWER COMPANY THE WESTERN MASSACHUSETTS ELECTRIC COMPANY MILLSTONE NUCLEAR POWER STATION. UNIT NO. 2 DOCKET NO. 50-336

1.0 INTRODUCTION

l By letter dated September 19,1995, the Northeast Nuclear Energy Company, et al.

(NNECO/the licensee), submitted a request to change the Millstone Nuclear Power Station, Unit No. 2 (MNPS-2), Technical Specifications (TSs). The requested change would reduce the frequency of the surveillance interval for the safety injection tanks (SITS) from once every 31 days to once every 6 months.

Specifically, the change was requested for TS Section 4.5.1.b. However, TS Section 4.5.1.b was subsequently changed to TS Section 4.5.1.d by Amendment No. 220 to Facility Operating License No. DPR-65, dated September 3,1998, in response to your application dated August 23,1995.

2.0 EVALUATION The MNPS-2 has four SITS that are passive pressure vessels which are partially filled with l

borated water and pressurized with a nitrogen cover gas. During the blowdown phase of a l

design basis loss-of-coolant, the reactor coolant system will depressurize and the nitrogen cover gas will cause the SITS to inject into the reactor vessel via the cold legs. TS 4.5.1.d has a surveillance requirement to verify the boron concentration of each SlT solution at least once per 31 days to demonstrate that the SITS are operable.

The request to reduce the frequency of SIT boron concentration surveillance is a follow-up to NRC Inspection Report 50-336/92-35, dated March 3,1993, which refers to the licensee evaluating the need for a TS change to reduce the frequency of the SIT surveillance which in turn would reduce the number of containment entries during power operation. The reduction in containment entries would reduce personnel radiological exposure in accordance with the licensee's policy to keep personnel exposures as-low-as-reasonably-achievable.

9812230328 981217 PDR ADOCK 05000336 P

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. The required minimum boron concentration of the SITS is 1720 parts per million (ppm). As L

stated in the licensee's submittal, the historical concentration data indicates that the boron concentration of the SITS has been greater than the required 1720 ppm during the period of 1981 l

through 1992, with the average and the lowest boron concentration being 1968 ppm and 1756 l

ppm, respectively. The two ways that SIT boron concentration can be reduced is through precipitation or dilution.

Precipitation occurs when the solution of borated water becomes so saturated that the boron settles out of the solution. The solubility limit of boric acid in water is 2.52 wt% at 32 *F, which corresponds to a boron concentration of approximately 4400 ppm. The boron concentration of l-the SITS is well below the solubility limit, which precludes boric acid concentration reduction due l

to boron precipitation.

l Dilution occurs due to the addition of water containing a lower boron concentration than the SITS.

A TS surveillance requirement to perform a boron concentration verification on a solution volume increase of a 1 percent of the tank volume has previously been added to TS 4.5.1.d to guard against this phenomenon. This surveillance requirement ensures that the correct boron.

concentration is maintained and dilution will not occur.

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SUMMARY

The NRC staff has reviewed the licensee's submittal requesting extension of the surveillance interval from every 31 days to every 6 months. The staff has determined that the proposed change to TS 4.5.1.d is acceptable. This determination is based on: (1) there is a TS l

surveillance requirement in the TSs to verify an SIT concentration anytime there is a change in a tank volume 21 percent, (2) the SIT boron concentration is well below the solubility limit of boron, (3) a change to en existing surveillance interval does not impact the Updated Final Safety Analysis Report, Chapter 14, transient analysis, and (4) personnel exposure to radiological exposure will be reduced.

4.0 STATE CONSULTATION

In accordance with the Commission's regulations, the Connecticut State official was notified of the proposed issuance of the amendment.. The State official had no comments.

5.0 ENVIRONMENTAL CONSIDERATION

The amendment changes surveillance requirements. 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 l'

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 (60 FR 54722 dated October 25,1995).

Accordingly, the amendment meets the eligibility criteria for categorical exclusion set forth in 10 l

CFR 51.22(c)(9). Pursuant to 10 CFR 51.22(b) no environmental impact statement or L

environmental assessment need be prepared in connection with the issuance of the amendment.

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6.0 CONCLUSION

l 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: S. Brewer Date: December 17, 1998 i

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