ML20236N500

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Forwards Technical Specification Interpretation for Auxiliary Feedwater & Safety Injection Systems Operability for Prairie Island 1 & 2 in Response to 970912 & 15 Requests
ML20236N500
Person / Time
Site: Prairie Island  Xcel Energy icon.png
Issue date: 10/18/1997
From: Beckner W
NRC (Affiliation Not Assigned)
To: Hannon J
NRC (Affiliation Not Assigned)
Shared Package
ML20236J990 List: ... further results
References
FOIA-98-155 TAC-M99666, TAC-M99667, TAC-M99669, TAC-M99670, NUDOCS 9807150148
Download: ML20236N500 (6)
v • d • e


Text

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October 18, 1997 4 . i MEMORANDUM TO: J:hn N. Hannon Prrject Dir:ct: rate 111-1 Division cf React:r '1ojects lil/IV, NRR t

FROM: William D. Beckner, Chief Technical Specifications Branch Original Signed By Associate Director for Projects, NRR

SUBJECT:

TECHNICAL SPECIFICATION INTERPRETATION FOR AUXlLIARY FEEDWATER AND SAFETY INJECTION SYSTEMS OPERABILITY - PRAIRIE ISLAND 1 AND 2 (7AC NOs. M99666, M99667, M99669, and M99670)

In letters to the NRC dated September 12 and 15,1997, Northern States Power (NSP) requested interpretations of the Prairie Island Technical Specifications (Pl TS) with respect to Safety injection (SI) System OPERABILITY during changing plant conditions and Auxiliary Feedwater System (AFW) OPERABILITY when the AFW pump selector switches are in MANUAL and SHUTDOWN AUTO positions and the pump discharge valves are throttled, respectively. The Technical Specifications Branch (TSB) has reviewed the two letters and supporting documentation. TSB's interpretation of the Pl TS for the Si and AFW Systems are included in Attachments 1,2, and 3.

TSB agrees with the licensee that the SI System is OPERABLE and there is no violation of the TS between RCS temperatures of 310' F and 200* F with both Si control switches in the pullout position, and that the operator has a reasonable amount of time to perform the actions necessary to place the control switch in the pullout or AUTO position at the RCS transition temperatures of 310' F and 200' F. However, TSB recommends that NSP request a TS change to eliminate any ambiguity or questions regarding OPERABILITY during changing plant conditions.

TSB also agrees with the licenses that P1 TS 3.4.B.1.c allows the AFW pump discharge valves to be throttled under administrative control during startup and shutdown operations.

However, TSB does not agree with the NSP interpretation that in MODE 2 with the AFW pump selector switch in SHUTDOWN AUTO or MANUAL position which disables Function 7.d - sutomatic AFW pump start on main feedwater pump trip - that the AFW system is OPFr1ABLE. Since Function 7.d is required to be OPERABLE in MODES 1 and 2 in act,ordance with Pl TS Table TS 3.5-28, placing the AFW pump selector switch in the SHUTDOWN AUTO or MANUAL position would violate the TS requirements and require enter into the appropriate ACTIONS. TSB recommends that NSP request a TS change to Table 75 3.5 2B to change the APPLICABILITY from MODES i and 2 to MODES 1 and 2 l above 2% power, as well as TS 3.4.B.1.c to explicitly state shutdown operations for the throttle valves.

Attachments: As stated DISTRIBUTION:

FILE CENTER FMReinhart TSB R/F

MWeston TSB Staff

\ _RPZimmerman NWDBeckner RJGiardina DOCUMENT NAME: G:\MWW/AFW123.Itr (WF6.1) i OFFICE TSB:ADPR:NRR TSB:ADPR:NRR TkADPR:NRJV C:TSB:ADPR:NRR NAME RJGiardinaqd_ MWWeshhFMRe WDBeckneN DATE 10/le/97 10//dS7 1[ /97\ 10//Y/97 OFFICIAL RECORD COPY 9807150148 980624 -- - - - - -

PDR FOIA l

UNNERST98-155 PDR l

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NUCLEAR REGULATORY COMMISSION WASHINGTON. D.C. 3D806 4001 9.....

MEMORANDUM TO: John N. Hannon l Project Directorate lil-1 Division of Reactor Projects Ill/lV, NRR , k V

FROM: William D. Beckner, Chief Technical Specifications Branch M

Associate Director for Projects, NRR

SUBJECT:

TECHNICAL SPECIFICATION INTERPRETATION FOR AUXILIARY FEEDWATER AND SAFETY INJECTION SYSTEMS OPERABILITY - PRAIRIE ISLAND 1 AND 2 (TAC NOs. M99666, M99667, M99669, and M99670) in letters to the NRC dated September 12 and 15,1997, Northem States Power (NSP) requested interpretations of the Prairie Island Technical Specifications (Pl TS) with respect to Safety injection (SI) System OPERABILITY during changing plant conditions and Auxiliary

'- Feedwater System (AFW) OPERABILITY when the AFW pump selector switches are in MANUAL and SHUTDOWN AUTO positions and the pump discharge valves are throttled, respectively. The Technical Specifications Branch (TSB) has reviewed the two letters and supporting documentation. TSB's interpretation of the Pl TS for the Si and AFW Systems l are included in Attachments 1,2, and 3.

TSB agrees with the licenses that the SI System is OPERABLE and there is no violation of the TS between RCS temperatures of 310' F and 200* F with both Si control switches in the pullout position, and that the operator has a reasonable amount of time to perform the actions necessary to place the control switch in the pullout or AUTO position at the RCS

transition temperatures of 310' F and 200' F. However, TSB recommends that NSP i

request a TS change to eliminate any ambiguity or questions regarding OPERABILITY during )

changing plant conditions.

TSB also agrees with the licenses that Pl TS 3.4.B.1.c allows the AFW pump discharge

! valves to be throttled under administrative control during startup and shutdown operations.

l However, TSB does not agree with the NSP interpretation that in MODE 2 with the AFW l pump selector switch in SHUTDOWN AUTO or MANUAL position which disables Function 7.d - automatic AFW pump start on main feedwater pump trip - that the AFW system is OPERABLE. Since Function 7.d is required to be OPERABLE in MODES 1 and 2 in accordance with PI TS Table TS 3.5 2B, placing the AFW pump selector switch in the SHUTDOWN AUTO or MANUAL position would violate the TS requirements and require entry into the appropriate ACTIONS. TSB recommends that NSP request a TS change to Table TS 3.5-2B to change the APPLICABILITY from MODES 1 and 2 to MODES 1 and 2 above 2% power, as well as TS 3.4.B.1.c to explicitly state shutdown operations for the throttle valves.

1 Attachments: As :tated CONTACT: R. J. Giardina, TSB (301) 415 3152 M. W. Weston, TSB (301) 415-3151 W-

,4 . .

Attachment 1 o Technical Specification interpretation for Safety injection System Operability During Movement into Different Plant Conditions.

Pl TS 3.3.A.1.c requires two Si pumps to be OPERABLE when the Reactor Coolant System (RCS) temperature is 2310' F . When the RCS temperature is <310' F, PI TS 3.3.A.3 and

,t 3.3.A.4 determine Si pump OPERABILITY. Pi TS 3.3.A.3 requires that at least one Si pump l control switch in the control room be in the pullout position whenever the RCS temperature

! <310' F, while 3.3.A.4 requires both SI pump control switches to be in the pullout position whenever the RCS temperature <200'F.

In an effort to satisfy both of these requirement, the Pl TS have recently been interpreted to require plant operators to instantaneously place the one remaining Si pump control switch in pullout when the RCS cools to 200* F . Ukewise, as the RCS is heated, when the plant l reaches 310' F, the second Si pump control switch is required to be instantaneously placed in the " AUTO" position. With the control switch in the " AUTO" position, no Si switches can be in pullout or the heatup has to be stopped. Yet, the SI pump control switch can not be placed in AUTO position prior to reaching 310' F because this would violate the l requirements of TS 3.3.A.3 which requires at least one Si pump control switch in pullout l when less than 310' F. Since you can not satisfy these requirements instantaneously, both l of these circumstances were considered non-compliance with TS requirements which l required reporting under 10 CFR 509.73 as a licenses event report (LER 1-97-09).

For changing plant conditions at 200' F, NSP has r&@.terpreted the TS to allow both SI pump control switches to be in pullout position. This is t.esed on the interpretation that l both TS 3.3.A.3 and 3.3.A.4 requirements can be met if tte TS phrase "at least one" is interpreted to allow both SI pump control switches to be placed in pullout prior to cooling down to 200' F. Thus, one switch will be placed in pullou'. 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 Si system at low RCS temperatures occur slowly and allow emple time for the operator l to manually place the SI system in service. The staff agrees that the phrase "at least one"

! will allow both Si control switches to be placed in the pullout position at anytime the RCS l

temperature is <310' F.  !

i 1 For changing plant conditions as the RCS temperature reaches 310' F, NSP interpreted TS l 3.3.A.1.c and TS 3.3.A.3 to allow some reasonable time f.or operators to place the second Si pump control switch in the AUTO position. This reasonable time does not require definition since the plant is not in any imminent danger if the second Si pump control switch is not instantaneously placed in the AUTO position. This is based on the fact that l the temperature of 310' F is a target temperature at which the operators take their actions to implement low temperature overpressure protection. However,it was not expected the operator actions would occur precisely at 310' F since the instrumentation which provides ,

the RCS temperature indication is not exact and this temperature was based on heatup and '

cooldown curves where a precise temperature was not calculated. Thus, it is not reasonable to expect operator action instantaneously at the precise temperature of 310* F.

The staff agrees with the licenses that the temperature is a target temperature at which actions need to be taken and that the actions cannot be taken instantaneously. However, the staff would expect the operator actions to be taken immediately upon reaching 310* F.

Immediately is defined in the STS (NUREGs 14301434) as actions that should be pursued

Attachmc.it 1 e

without delay and in a controlled manner. Thus, the staff agrees with the licenses that a reasonable time limit for operator action is acceptable. However, TSB recommends that NSP request a TS change to eliminate any ambiguity or questions regarding OPERABILITY during changing plant conditions.

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l Attachment 2 l

Technical Sp:cificati:ns Int:rpr:tati:n f r Auxill ry Feedwat:r System Oper bility with l

Throttled Pump Discharge Valves.

Whenever the unit is critical or the RCS average temperature exceeds 350' F, for single unit operation, TS 3.4.B.1.s requires the turbine driven AFW pump associated with the operating reactor and a motor driven AFW pump be OPERABLE and for two unit operation, TS 3.4.8.1.b requires all four plant AFW pumps to be OPERABLE. TS 3.4.B.1.c requires all valves and piping associated with the AFW pumps to be OPERABLE whenever the unit is critical or the RCS average temperature exceeds 350' F. This specification makes an exception that "during STARTUP OPERATION necessary changes may be made in motor-l operated valve position". During normal plant startup and shutdown operation, the AFW l pump discharge valves are throttled to control steam generator levels. NSP questions l whether the AFW pump discharge valves are OPERABLE when they are throttled ,

particularly during shutdown operations. The staff has reviewed TS 3.4.B.1.c and concludes that the term *STARTUP OPERATION"is encompasses to MODES 2 thru 4 in the P1 TS. However, based on the definition of STARTUP OPERATION in Section 1.0 of the Pl TS, the words "during STARTUP OPERATION" apply only when the plant is going up in power (startup). For shutdown operations the Pl TS are not as explicit. However, the staff l

concludes that the definition of OPERABLE - OPERABILITY in Section 1.0, the Objective of TS 3.4

  • assure the capability of removing decay heat from the reactor," and the allowance to change the throttle valves position on start-up and manual valve position during operations, provides sufficient justification to conclude that the throttle valves can he throttled during shutdown operations. Thus, there is no question that the AFW pump discharge valves can be throttled as long as the throttling is done under direct administrative control, and that the valves and the system are considered OPERABLE.

l However, the staff recommends that TS 3.4.B.1.c be modified to explicitly state that the l motor operated valves' position can be changed both on startup and shutdown. ,

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Attachment 3

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Technical Specifications interpretation for Auxillary Foodwater System Operability with AFW Pump Selector Switch in Shutdown Auto in MODE 2.

AFW pump selector switches have three positions, AUTO, MANUAL, and SHUTDOWN AUTO. When the selector switch is in the AUTO position, all required automatic AFW start functions listed in Table TS 3.5-2B are unabled for the AFW pump. In the MANUAL position the AFW pump can be started or stopped by placing the associated pump control switch in the START or STOP positions, respectively. In the MANUAL position, no automatic AFW pump start functions apply to the pump. The SHUTDOWN AUTO position enables all automatic AFW start functions on the pumps except the automatic start for loss of both l

main feedwater pumps. P1 TS Table TS 3.5-28 requires the AFW system to automatically

! start for Function 7.e (SI) during MODES 1,2,3 and/or 4, for Functions 7.b, and 7.f during l MODES 1,2, and 3 and for Functions 7.c and 7.d during MODES 1 and 2. Function 7.d is l the trip of both main feedwater pumps.

l During startup and shutdown operation when there is e low feed demand, the normal

[ . method for providing steam generator feedwater is by using the motor driven AFW pump.

l This in required because at low power levels, extended operation of the main feedwater pumps in the recirculation mode would cause damage to the main feedwater pumps due to heating and vibration of the pumps. Thus, safe, prudent operation of the plant requires l

placement of the AFW pump selector switches in SHUTDOWN AUTO during plant startup and shutdown. During startup operations, as the plant approaches 2% power the motor I driven AFW pump is operating and both putnp selector switches are in SHUTDOWN AUTO.

l The first main feedwater pump !s started and once stable operation is confirmed, the motor l driven AFW pump selector switch is briefly placed in MANUAL, the pump control switch is turned to STOP to secure the pump and then the AFW pump selector switch is set on ,

AUTO. Likewise, during plant shutdown, once the plant is below 2% power one AFW l pump selector switch is momentarily torned to MANUAL, the pump is started and then the switch is placed in the SHUTDOWN AUTO position and the other AFW pump selector l switch is placed in SHUTDOWN AUTO. 'Then the last operating main feedwater pump is secured. During both startup and shutdown evaluations the AFW pump selector switches are temporarily in SHUTDOWN AUTO or MAHUAL while a main feedwater pump is operating.

l Thus, NSP proposed that the P1 TS Table TS 3.5-2B Functional Unit 7.d requirement for MODE 2 OPERABILITY be interpreted to only reiluire automatic AFW pump start on loss of both main feedwater pumps when one or both risin feedweter pumps are required for operation in MODE 2, and that AFW pumps be considered OPERABLE within the

requirements to Table TS 3.5 28, Functional Unit 7.d for the brief period of time when the AFW pumps are operating in SHUTDOWN AUTO or MANUAL while the main feedwater pumps are operating.

The staff has reviewed the subject TS and concludes that the NSP interpretation is not correct. The TS require Functional Unit 7.d to be OPERABLE in MODE 2, placing the AFW l pump selector switch in the SHUTDOWN AUTO or MANUAL positions makes this function (7.d), as well as the other AFW start functions for the manual position, inoperable. This  ;

then would require entry into the appropriate ACTIONS for the TS for inoperable instrumentation and/or AFW systerr. While the staff agrees that use of the AFW system during startup and shutdown to avoid main feedwater pump damage is required at Prairie Island,interpretating the TS to allow this type of operation is not correct. The TS should be revised to limit the OPERABILITY of fanctional Unit 7.d to MODE 2 above 2% power or other quantifible limit.

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