ML19322A133
| ML19322A133 | |
| Person / Time | |
|---|---|
| Site: | Maine Yankee |
| Issue date: | 12/29/1978 |
| From: | Johnson W Maine Yankee |
| To: | Reid R Office of Nuclear Reactor Regulation |
| References | |
| WMY-78-111, NUDOCS 7901030018 | |
| Download: ML19322A133 (2) | |
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B.3.2.1 EMY 78-111 December 29, 1978 United States Nuclear Regulatory Cornission Washington, D. C.
20555 Attention: Office of Nuclear Reactor Regulation Robert W. Reid, Chief Operating Reactors Branch #4 Division of Operating Reactors
References:
(a) License No. DPR-36 (Docket 50-309)
(b) USNRC Letter from Robert W. Reid DOR to R. H. Groce dated November 29, 1978
Dear Sir:
Subject:
Containment Purging During Normal Plant Operation Reference (b) requested that the Meine Yankee Atomic Power Company provide the Cocsission with either (1) a co==itment to cease all contain-ment purge during operation, or (2) justification for its continued practice.
It is our position that the practice of purging during normal plant operation can be justified for the Maine Yankee plant. We have initiated an evaluation effort which will address those issues which relate to purging during normal operation which are described in Section 6.2.4, Revision 1 of the Standard Review Plan and in the associated Branch Technical Position. We feel confident that this evaluation, when com-pleted, will provide the justification for purging during operation.
It is presently anticipated that the evaluation effort will be completed by June 1, 1979. The report of our evaluation will be sub-mitted to you no later than June 15, 1979.
During the period in which the evaluation effort is being performed, and pending NRC staff review of the result, Maine Yankee, in accordance with a request made in reference (b), coenits to limit containment purging during operation to a minimum which will not exceed 90 hours0.00104 days <br />0.025 hours <br />1.488095e-4 weeks <br />3.4245e-5 months <br /> per year.
Relative to the additional request rade in reference (b) for the performance of a review of all safety actuation signal circuits which incorporate a manual override, the following information is provided.
The safety actuation signals at Maine Yankee do not incorporate manual override capabilities. System design utilizes a manually activated 790103 cot 8 r
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United States Nuclear Regulatory Commission December 29, 1978 Attention: Office of Nuclear Reactor Regulation Page 2 blocking circuit that can only be activated below specified reactor coolant pressure conditions. This design also includes an auto-removal of the blocking circuit should system pressure increase above the block-ing permissive setpoint. There is, however, one evolution which requires use of two " jumpers" to bypass one portion of a safety signal.
The Containment Purge System isolation valves are designed to auto-matica11y close on either a Containment Isolation Signal (CIS) or on a high alarm on one of four specific channels of the Radiation Monitoring Signal (RMS).
Following the performance of a 10CFR50.54, Appendix J, Class A pressure test of the containment, " jumpers" are inserted across a set of contacts for one of the Containment Purge System outlet valves and the 4" bypass valve around the other purge outlet valve.
These
" jumpers" only defeat the auto-closure signal frcm the CIS which would be activated at this time whereas containment pressure would be greater than the 5 psig, CIS setpoint. By using these two " jumpers," it is Possible to open these two valves and slowly de-pressurize the contain-ment while still retaining the auto-closure feature associated with RMS which is required by Technical Specifications.
The control of these bypass " jumpers" is by two separate and distinct methods. First, the installation of any " jumper" is administratively controlled by the use of special tagging instructicns and procedures which require authorization and observation by two separate individuals for both installation and removal. The log book associated with these tags is reviewed by the Plant Shif t Superintendent once each shif t.
Secondly the procedure for performing the Class A Containment pressure test has separate steps requiring an individual sign-off for both the installation and removal of the specific " jumpers" associated with this bypass.
Because this bypass is only utilized for purposes of dqpressurizing the Containment following a Class A pressure test, and due to the redundant sign-offs, witnesses, and other administrative and procedural controls, the installation of a separate annunciator for this one " jumper" bypass is not felt necessary or justified.
We trust that our evaluation schedule is satisfactory and that the information provided relative to our review of safety actuation signals is adequate; however, should additional information be required, please contact us.
Very truly yours, MAINE YANKEE ATOMIC POWER COMPANY
'IY Sf W. P. Johnson Vice President 1
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