Northeast Nuclear Energy Company, et al.; Millstone Nuclear Power Station, Unit No. 3, Environmental Assessment and Finding of No Significant Impact

NUCLEAR REGULATORY COMMISSION

[Docket No. 50-423]

Northeast Nuclear Energy Company, et al.; Millstone Nuclear Power

Station, Unit No. 3, Environmental Assessment and Finding of No

Significant Impact

The U.S. Nuclear Regulatory Commission (the Commission) is

considering issuance of an amendment to Facility Operating License No.

NPF-49, issued to Northeast Nuclear Energy Company (NNECO or the

licensee), for operation of the Millstone Nuclear Power Station, Unit

No. 3 (MP3), located in New London County, Connecticut.

Environmental Assessment

Identification of the Proposed Action

The proposed action would revise the analysis for the design basis

loss-of-coolant accident (LOCA) to include the dose contribution from a

previously unevaluated radioactivity release pathway to the

environment. The licensee identified a potential pathway for post

accident back-leakage of highly radioactive containment sump water from

the Recirculation Spray System (RSS) to the Refueling Water Storage

Tank (RWST). Since the RWST is

[[Page 58107]]

vented to the atmosphere, this pathway could contribute to an

inadvertent release of radioactivity not previously accounted for in

offsite dose calculations. Previously, the licensee had assumed no

radiological consequences due to back-leakage. This revision adds the

dose from RWST back-leakage to the LOCA analysis, as documented in the

Final Safety Analysis Report (FSAR).

The proposed action is in accordance with the licensee's

application for amendment dated May 7, 1998, as supplemented by letter

dated January 22, 1999.

The Need for the Proposed Action

Pursuant to 10 CFR 50.59 licensees are required to obtain prior NRC

approval of changes to the facility that involve an unreviewed safety

question. The licensee determined that the back-leakage from RSS to the

RWST involves an unreviewed safety question. Therefore, the licensee

was required to obtain prior NRC approval for changes to the LOCA

analysis and the FSAR to incorporate the dose consequences of the

potential for back-leakage from the RSS to the RWST that had not been

previously accounted for in offsite dose calculations.

Environmental Impacts of the Proposed Action

The NRC has completed its evaluation of the proposed action and

concluded that the contribution to the LOCA dose to the thyroid (most

limiting organ) from the RWST back-leakage as calculated by the

licensee is small (2.1 rem at the Low Population Zone (LPZ) and 0.9 rem

at the Control Room). When added to the licensee's previously

calculated doses, the affected LOCA doses to the thyroid are 11 rem at

the LPZ and 12 rem at the Control Room. The increase are small when

compared to, and these results continue to meet the acceptance criteria

in, 10 CFR Part 100 for the offsite dose consequences and in 10 CFR

Part 50, Appendix A, General Design Criterion (GDC) 19 for the control

room. All other offsite and control room doses were unchanged. On this

basis the staff determined there is no significant radiological

environmental impact.

The proposed action will not increase the probability or

consequences of accidents, no changes are being made in the types of

any effluents that may be released off site, and there is no

significant increase in occupational or public radiation exposure.

Therefore, there are no significant radiological environmental impacts

associated with the proposed action.

With regard to potential non-radiological impacts, the proposed

action does not involve any historic sites. It does not affect non-

radiological plant effluents and has no other environmental impact.

Therefore, there are no significant non-radiological environmental

impacts associated with the proposed action.

Accordingly, the NRC concludes that there are no significant

environmental impacts associated with the proposed action.

Alternatives to the Proposed Action

As an alternative to the proposed action the staff considered

requiring the licensee to maintain zero back-leakage from the RSS to

the RWST. Since this is the original analysis condition, this

alternative is the same as the staff denying the proposed action (i.e.,

the ``no-action'' alternative). Zero back-leakage cannot be ensured for

the valves between the RSS and the RWST; therefore, this alternative is

impractical. Denial of the proposed action would result in no change in

current environmental impacts. The environmental impacts of the

proposed action and the alternative action are similar.

Alternative Use of Resources

This action does not involve the use of any resources not

previously considered in the ``Final Environmental Statement Related to

the Operation of Millstone Nuclear Power Station, Unit No. 3,'' dated

December 1984 (NUREG-1064).

Agencies and Persons Consulted

In accordance with its stated policy, on September 23, 1999, the

staff consulted with the Connecticut State official, Mr. Fred

Scheuritzel of the Department of Environmental Protection, regarding

the environmental impact of the proposed action. The State official had

no comments.

Finding of No Significant Impact

On the basis of the environmental assessment, the NRC concludes

that the proposed action will not have a significant effect on the

quality of the human environment. Accordingly, the NRC has determined

not to prepare an environmental impact statement for the proposed

action.

For further details with respect to the proposed action, see the

licensee's letter dated May 7, 1998, as supplemented by letter dated

January 22, 1999, which are available for public inspection at the

Commission's Public Document Room, The Gelman Building, 2120 L Street,

NW., Washington, DC, and at the local public document rooms located at

the Learning Resources Center, Three Rivers Community-Technical

College, 574 New London Turnpike, Norwich, Connecticut, and the

Waterford Library, 49 Rope Ferry Road, Waterford, Connecticut.

Dated at Rockville, Maryland, this 22nd day of October 1999.

For the Nuclear Regulatory Commission.

John A. Nakoski, Sr.,

Project Manager, Section 2, Project Directorate I, Division of

Licensing Project Management, Office of Nuclear Reactor Regulation.

[FR Doc. 99-28228 Filed 10-27-99; 8:45 am]

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