ML19289E752

Responds to IE Bulletin 79-06A.Expresses Concern Re Emergency Operating Procedures for Reactor Coolant Pump & Requirement for Immediate Tripping of Low Level Bistables

ML19289E752
Person / Time
Site:	Point Beach
Issue date:	04/19/1979
From:	Burstein S WISCONSIN ELECTRIC POWER CO.
To:	James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
References
NUDOCS 7905290075
Download: ML19289E752 (3)

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l WISCODSin Electnc vow con 231 WEST MICHIG AN.f/lLA AUKEE, AISCONSIN 53201 April 19, 1979 Mr . J ame s G . Keppler, Regional Director Office of Inspection and Enforcement, Region III U. S. NUCLEAR REGULATORY COMMISSION 799 Roosevelt Road Glen Ellyn, Illinois 60137

Dear Mr. Keppler:

DOCKETS 266 and 50-301 COMMENTS ON BULLETIN 79-06A POINT BEACH NUCLEAR PLANT UNITS 1 and 2 We have completed our initial review of IE Bulletin 79-06A in respect to actions to be taken in regard to Point Beach Nuclear Plant activities as a result of preliminary analysis of the Three Mile Island accident. We plan to respond more fully within the requested ten-day period.

During our initial review, however, we note two items in this Bulletin which appear to be directives requiring immediate action on our part. We are concerned that these imply actions to be taken prior to the time when normal administrative procedures and established safety reviews can be properly conducted. Without these safety reviews, we are concerned that these two items might place our f acilities in a less safe condition or might cause plant procedures to be changed in such a manner as to result in less conservative reactor operation than was assumed in the plant safety analyses.

Our first item of concern is listed as Item (3) in Bulletin 79-06A. This item appears to require the.immediate tripping of the pressurizer low-level bistables so'that when pressurizer pressure reaches its low setpoint, safety injection would be initiated irrespective of pressurizer level. We are presently performing the safety review and preparing the appropriate modification request which will remove the pressurizer low-level signal actuation circuitry. It is our present preliminary position that this modification should provide for a two-out-of-three, or a two-out-of-four, pressurizer low-pressure actuation 7905290015 2046 $42

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Mr. J. G. Xeppler April 19, 1979 e

of safety injection. We believe that the requested action of placing the pressurizer low-level bistables in the tripped condition could reduce plant safety since it results in a one-out-of-three low-pressure actuation of safety injection.

This logic prevents normal periodic testing of part of the protection circuitry. We believe the inability to perform such testing is an undesirable consequence of such an immediate action as appears to be required by this Item (3).

This logic is also susceptible to spurious actuation of safety injection, which we believe is also to be avoided.

We believe you will agree that the safety injection system is designed to mitigate anomalous plant conditions that are already in progress. This design principle is different from the reactor protection system, which is, of course, intended to prevent plant parameters from reaching undesirable conditions. At Point Beach Nuclear Plant, the actuation of safety injection causes the normal protective functions of reactor trip and turbine trip to occur, as well as the mitigating functions of containment isolation. These include feedwater isolation, containment ventilation isolation, and the start-up of high-pressure safety injection pumps, low-pressure injection pumps, containment fan coolers, auxiliary feedwater pumps, service water pumps, and emergency diesels. Containment isolation also causes the loss of normal charging and let-down systems, the isolation of instrument air to air-operated devices within containment, as well as the loss of main feedwater supply.

Based on our understanding of the Three Mile Island accident and the event which is postulated to have the possibility of resulting in erroneous pressurizer level indication, we believe that for the Point Beach Nuclear Plant, such an event would occur fairly slowly over a significant period of time. Hence, we believe the instructions to the plant operating staff to initiate safety injection manually should be sufficient protection fer the interim time it takes us to evaluate and modify the actuation circuitry to achieve the appropriate function.

The second item of cur concern is listed as Item (7) (c) in Bulletin 79-06A. This reference seems to require an immediate change to our emergency operating procedures to require continuous operation of at least one reactor coolant pump. You will recall that the Point Beach Plant design has been analyzed to be safe in the event of a loss of off-site electrical power which causes the tripping of rehetor coolant pumps. The continued operation of reactor coolant pumps during some accidents may be less conservative than turning the pumps off. We are, of course, reviewing the operation of the reactor coolant pumps during various accidents as part of our analysis of the Three Mile Island accident in appropriate relationship to the design and safety analysis of the Point Beach Nuclear Plant. Any changes to our emergency plant operating procedures in respect to reactor coolant pump operations, as well as other matters, will be made in the appropriate manner.

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4 Mr. J. G. Keppler April 19, 1979 There are two additional items in Bulletin 79-06A to which we would make preliminary response at this time. The criteria for terminating safety injection outlined in Items (7) (a) and (7) (b) will require careful review in relationship to the design of our facility prior to proposing modifications to plant procedures. Since the Point Beach Nuclear Plant has automatic feedwater actuation, the need to station an operator manually to initiate auxiliary feedwater, as specified in Item (5), is not applicable to our facility. We might suggest that the Commission staff review this requirement in non-Babcock & Wilcox plants because of the significantly larger secondary side water inventory in recirculation-type steam generators, which allows a longer period of time for an operator to assess the plant condition and manually to initiate auxiliary feedwater.

We have, of course, followed closely your reports of the Three Mile Island accident. We appreciate your making these progress reports available to us in a timely manner.

Our review and evaluation of this serious accident have commanded our priority attention. We are directing our efforts toward performing a careful and diligent review to achieve an expeditious and complete analysis, but which also seeks to avoid premature reactions which, in themselves, might reduce the safety of the plant. We thank you again for keeping us fully informed.

Very truly yours,

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Exe utive Vice President Sol Burstein 2046 $44

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