ML20216H714
| ML20216H714 | |
| Person / Time | |
|---|---|
| Site: | Prairie Island  |
| Issue date: | 09/12/1997 |
| From: | Sorensen J NORTHERN STATES POWER CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 9709170042 | |
| Download: ML20216H714 (4) | |
Text
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Northern states Power Company 1717 Wakonado Dr. E.
Welch. MN 55089 Telephono 612 3881121 September 12,1997 U S Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555 PRAIRIE ISLAND NUCLEAR GENERATING PLANT Docket Nt.s. 50 282 License Nos. DPR-42 50 306 DPR-60 Technical Specification Interpretation for Safety injection System Operability Durina Movement into Different Plant Conditions Reference 1: LER 1-97-09, Unavoidable Momentary Non-compliances with Technical Specification Requirements Which Do Not Provide a Time Interval to Establish Different Plant Equipment Configuration Upon Moving into Different Plant Conditions NSP requests an interpretation of the PI Technical Specifications to address requirements of the Technical Specifications with respect to safety injection system operability during changing plant conditions which are not physically attainable.
Reference 1 describe the circumstances whereby the Technical Specifications have recently been interpreted to require plant operators to instantaneously place the one remaining safety injection pump control switch in pullout when the RCS cools to 200 *F. Likewise, as the RCS is heated, the instantaneous moment the plant reaches 310 *F the second safety injection pump control switch is required to be placed in the " AUTO" position (no safety injection switches can be in pullout) or
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the heatup has to be stopped. The safety injection pump control switch can not be
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placed in AUTO position (taken out of pullout) prior to reaching 310 'F since this
/ O would violate TS.3.3.A.3 which requires at least one safety injection pump control
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switch in pullout when less than 310 *F. Both of these circumstances have been
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considered non-compliance with Technical Specification requirements which require reporting under 10 CFR 50.73 as a licensee event report (LER).
In general, we do not believe that the NRC STAFF or the authors of these Technical Specifications envisioned narrow interpretation of the Technical Specifications such that plant start up or shut down would either require non-compliance with the 9709170042 970912
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- Paga 2 of 4 Technical Specifications or be completely prevented. The Techn; cal Specification actions at 200 *F and 310 *F are provided to protect the plant and in turn the health and safety of the public. The expectation was that the required actions would be taken within a reasonable time by attentive operators once these temperatures are reached. The required actions at each temperature were not intended to present the operators with a dilemma each time a transition temperature is reached such that the operator wou!d be in non-compliance (unable to instantaneously change equipment status at the precise temperature) or be prevented from passing through the temperature (prevented from shutting down or starting up). Technical Specifications are written to assure safe plant operation, not to prevent it from operating. Also, the Technical Specifications are written with the intent that during normal plant evolutions, such as start up or shut down, the plant will remain in compliance.
For changing plant conditions at 200 *F, NSP requests an interpretation of the Technical Specifications with respect to allowing both safety injection pump control switches to be in pullout when the Technical Specifications state that "at least one" pump control switch shall be in pullout. Safety injection system Technical Specification, TS.3.3.A.4, requires, "Both safety injection pump control switches" to be in pullout whenever RCS temperature is less than 200 *F while TS TS.3.3.A.3 requires, "At least one safety injection pump control switch" to be in pull out whenever the RCS temperature is less than 310 *F. Both of these requirements can be met if the Technical Specification phrase "At least one" is interpreted to allow both safety injection pump control switches to be placed in pullout prior to cooling down to 200 *F. Thus, one switch will be placed in pullout when the RCS is below 310 *F until the temperature approaches 200 *F. At that time both switches will be placed in pullout. This maintains the plant in a safe condition since events which require operation of the safety injection system at low RCS temperatures occur slowly and allow ample time for operators to manually place the safety injection system in service. Therefore, placement of both safety injection pump control switches in pullout as the RCS temperature approaches 200 *F in a plant cool down meets the verbatim word requirements of the Technical Specifications and maintains plant safety.
For_ changing plant conditions as the RCS temperature passes 310 *F, NSP requests an interpretation with respect to the time frame in which the operators must complete their actions. NSP's interprets Technical Specifications TS.3.3.A.1.c and TS.3.3.A.3 to allow some reasonable time for operators to place the second safety injection pump control switch in the " AUTO" position. This " reasonable time" does not require definition since, as discussed below, the plant is not in any imminent danger if the second safety injection pump control switch is not immediately placed in the AUTO position.
USNRC 9/12/97 Paga 3 of 4 The temperature of 310 *F is stated in the Technical Specifications since the operators have to have a target temperature at which they take their actions to implement low temperature overpressure protection. However, it was not expected that operator actions would occur precisely at 310 'F. The instrumentation which provides the RCS temperature indication is not exact and can have errors which can indicate either a temperature higher or lower than the actual RCS temperature. Also determination of 310 'F RCS temperature for implementation of low temperature overpressure protection was not a precise calculation. This temperature was based on heatup and cooldown curves and a precise temperature was not calculated.
Thus it is not reasonable to expect operator action instantaneously at the precise temperature of 310 'F.
Furthermore, it should be noted that the PI Technical Specification requirement to have two safety injection pumps operable when the RCS temperature is equal to or above 310 *F is not consistent with the guidance of NUREG-1431, " Standard Technical Specifications, Westinghouse Plants". NUREG-1431 requires two trains of safety injection (ECCS) operable in MODES 1,2, and 3. In MODE 4, which is operation between 350 'F and 200 'F, only one train of safety injection (ECCS) is required to be operable. Pl intends to convert the Technical Specifications to conform to the guidance of NUREG-1431. These converted Technical Specifications, the Pi improved Technical Specifications, will adopt the NUREG-1431 requirement that only one train of safety injection (ECCS) is operable in MODE
- 4. Thus, the issue of timely restoration of the second safety injection pump control switch will be moot in the PI improved Technical Specifications since only a single safety injection pump will be required to be operable up to 350 'F. This ic safe due to the stable conditions associated with plant operations in MODE 4 and the reduced probability of occurrence of a design basis accident. With the stable operations and reduced design basis accident probability in this MODE, certain automatic safety injection actuations are not required. Since only one train of safety injection is required, single failures are not considered due to the time available for operators to respond to an accident. With the Pi improved Technical Specifications, this dilemma of compliance with equipment status changes at 310 *F RCS temperature will not occur since between the temperatures of 310 *F and 350 'F only one train will be reauired to be operable but both trains may be operable.
Therefore, the operators will be allowed to place the second safety injection pump control switch in AUTO prior to reaching MODE 3.
NSP believes that the public health and safety would best be served by interpreting the current Prairie Island Technical Specifications as proposed in this letter.
Through these interpretations the plant is able to continue operation in a safe manner, in compliance with the Technical Specifications and without preparation of LERs.
USNRC 9/12/97 Pcg3 4 of 4 Yobr timely response to this request for interpretation would be appreciated, since Prairie Island Unit 1 is scheduled to shutdown for refueling on October 18,1997 and tne safety injection system switches will have to be manipulated to support the plant shutdown evolutions. In this letter we have made no new Nuclear Regulatory Commission commitments. if you have any questions related to this letter, please -
contact myself or Dale Vincent at 612-388-1121.
/AY i
O*t Joel P Sorensen Plant Manager, Prairie Island Nuclear Generating Plant c:
Regional Administrator - 111, NRC NRR Project Manager, NRC Senior Resident inspector, NRC State of Minnesota Attn: Kris Sanda J E Silberg I
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