ML20137J035

Discusses Potential Significant Hazards Consideration for Proposed Change 113 Re RCS Vents,Per NRC Request.Proposed Change 113 Only Addresses Operability & Surveillance Requirements.Nshc Exists

ML20137J035
Person / Time
Site:	Maine Yankee
Issue date:	01/15/1986
From:	Whittier G Maine Yankee
To:	NRC OFFICE OF ADMINISTRATION (ADM), Office of Nuclear Reactor Regulation
References
RTR-NUREG-0737, RTR-NUREG-737, TASK-2.B.1, TASK-TM 6856L-FWS, GDW-86-18, MN-86-08, MN-86-8, NUDOCS 8601220216
Download: ML20137J035 (3)

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- MN-86-08 GOW-86-18 Director of Nuclear Reactor Regulation United States Nuclear Regulatory Commission Washington, D. C. 20555 Attention: Document Control Desk

References:

(a) License No. OPR-36 (Docket No. 50-309)

(b) USNRC Letter to MYAPCo dated September 8, 1983 -

NUREG-0737, Item II.B.1, Reactor Coolant System Vents -

Maine Yankee Atomic Power Station (c) MYAPCo Letter to USNRC dated March 13, 1985 - Reactor coolant System Vent System (MN-85-38) (PC #113)

Subject:

Significant Hazards Consideration for Proposed Change #113 Gentlemen:

Recently, our NRR Project Manager informed us that the Staff desires a more thorough discussion of potential significant hazards considerations for our Proposed Change #113 concerning Reactor Coolant System Vents. This letter is in response to that request.

We reviewed the various submittals we have made regarding the design and installation of the RCS vents and, in particular, the Staff Safety Evaluation Report, Reference (b), and the applicable portion af the Commission's Rules 10 CFR 50.44(c)(3)(lii). Proposed Change 113 only addresses the operability and surviellance requirements for the system. The desirability of the system was decided as a matter of rule by the Commission; the design and installation have been dealt with previously.

Since:

0 the vent system is required by Rule; the vent system was installed according to a Staff reviewed and approved design; the proposed Technical Specifications follow guidance for operability contained in Generic Letter 83-37; appropriate surveillance requirements are included in accordance with the recommendations of Reference (b) and Generic Letter 83-37; B601220216 860115 c PDR ADOCK 05000309 ^

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United States Nuclear Regulatory Commission Page Two Attention: Document Control Desk MN-86-08 o the proposed change forbids the valves even having power to the actuators above Condition 4; and this system has no control function but serves only to mitigate the effects of certain types of accidents, we have concluded that no significant hazards consideration exists. Our specific answers to the three questions implied by 10 CFR 50.92 are summarized in the attachment to this letter.

We hope that this discussion fulfills your needs.

Very truly yours, MAItE YANKEE ATOMIC POWER C0bPANY

'[A fawkw G. D. Whittier, Manager Nuclear Engineering & Licensing FWS/bjp Attachment cc: Mr. Ashok C. Thadani Dr. Thomas E. Murley Mr. Cornelius F. Holden 4

6856L-FWS

y MAINE YANKEEIATOMIC POWER COMPANY ATTACH ENT A. Does this proposed change increase the probability or consequences of a previously analyzed accident? ,

No. Because this change simply requires four valves to be shut and to be operable with power removed from their actuators at or above Condition 4.

Additionally, even if the valves were to be inadvertently opened at power and left that way despite alarms and other indications to the operator, the system was designed such that flow through the lines would be within the capacity of normal charging.

B. Does this change create the possibility of a new or different kind of accident from any previously analyzed accident?

No. Because potential incidents were assessed by the Commission when considering the rule which requires RCS vents and because the Staff has specifically reviewed and approved Maine Yankee's design which included potential accident considerations.

C. Does this change significantly decreas; any margin of safety?

No. Because an operable RCS Vent System makes possible better mitigation of postulated accidents in which non-condensible gasses might accumulate in the pressurizer or in the reactor vessel. Thus, the margin of safety is actually improved.

6856L-FWS