ML20128E949

Forwards Response to License Condition C(13) Re Low Temp Overpressure Protection.Reliance on Administrative Controls, W/Addition of Alarm Circuits on Valves,Provides More Protection for Both RCS & RHR Sys than Interlocks

ML20128E949
Person / Time
Site:	Wolf Creek
Issue date:	05/22/1985
From:	Koester G KANSAS GAS & ELECTRIC CO.
To:	Harold Denton Office of Nuclear Reactor Regulation
References
KMLNRC-85-122, TAC-61963, NUDOCS 8505290517
Download: ML20128E949 (8)

Text

V KANSAS GAS AND ELECTRIC COMPANY T>E ELECTAC COMPANY OLENN L etOESTER VICE p*EssDENT huCLEAfD May 22, 1985 Mr. Harold R. Denton, Director Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, D.C.

20555 KMLNRC 85-122 Re:

Docket No. STN 50-482 Subj: Wolf Creek License Condition C (13)

Dear Mr. Denton:

The attachments to this letter provide Kansas Gas and Electric Company's (KG&E) response to the Wolf Creek Facility Operating License NPF-32 License Condition C (13) concerning low temperature overpressure protection.

If you have any questions concerning this subject, please contact me or Mr. Otto Maynard of my staff.

Yours very truly, 4

GLK:bb Attach xc:PO'Connor (2), w/a JCummins, w/a 9505290517 850522 h

PDR ADOCK 05000482 P

pop r5 201 N. Market - WicNta, Kansas - Mail Address: PO. Box 208 I Wichita, Kansas 67201 - Telephone: Area Code (316) 2616451

y OATH OF AFFIRMATION STATE OF KANSAS

)

) SS:

COUNTY OF SEDGWICK )

I, Glenn L. Koester, of lawful age, being duly sworn upon oath, do depose, state and affirm that I am vice President - Nuclear of Kansas Gas and Electric Company, Wichita, Kansas, that I have signed the foregoing letter of transmittal, know the contents thereof, and that all statements contained therein are true.

KANSAS GAS AND ELECTRIC COMPANY By h

"Clenn L. Koester

~

Vice President - Nuclear

. E.D. Prothro, Assistant Secretary STATE OF KANSAS

)

) SS:

COUNTY OF SEDGWICK )

BE IT REMEMBERED that on this 22nd day of May, 1985 before me, Evelyn L. Fry, a Notary, personally appeared Glenn L. Koester, Vice President - Nuclear of Kansas Gas and Electric Company, Wichita, Kansas, who is personally known to me and who executed the foregoing instrument, and he duly acknowledged the execution of the same for and on behalf of and as the act and deed of said corporation.

IN WITNESS WHEREOF, I have hereunto set my hand and affixed my seal the 4',W((eM,,and year above written.

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... to KMLNRC 85-122 1 of 4 Low Temperature Overpressure Protection his information is being provided in response to license condition C(13) of Facility Operating License NPF-32 for Wolf Creek Generating Station, Unit 1.

which states:

~(13) Iow Tenperature Overpressure Protection -(Section 5, SSER #5)

By June 1,1985, KG&E shall submit for NRC review and @ proval a description of equipnent modifications to the residual heat removal system (RHRS) suction isolation valves md to closure circuitry which conform to the applicable staff requirenents (SRP 5.2.2). Within one year of receiving NBC @ proval of the modifications, KG&E shall have the approved modifications installed. Alternately, by June 1,1985, KG&E shall provide acceptable justification for reliance on a&ninistratIve means alone to meet the staff's RHRS isolation requirements, or otherwise, propose changes to Appendix A to this license which remove reliance on the RHRS as a means ~ of low temperature overpressure protection.

In-taking credit for the RHRS suction isolation valves for Cold Overpressurization Protection, there are two Standard Review Plan (SRP) sections and two Branch Technical Positions which must be a$ dressed. '1hese are SRP 5.2.2 "OVERPRESSURIZATION PR0rBCTION" ed its associated Branch Technical Position RSB 5-2 "OVERPRESSURIZATION PROTECTION OF PRESSURIZED

~ WATER REAC'IORS WHILE OPERATING AT IAW TEMPERATURES" and SRP 5.4.7 " RESIDUAL HEAT REMOVAL (RHR) SYSTEM" and its associated Branch Technical Position RSB 5-1, " DESIGN REQUIREMENTS OF THE. RESIDUAL HEAT REMOVAL SYSTEM." A discussion of conpliance with these positions follows.

I.

STANDARD REVIEW PLAN 5.2.2 AND BRAPCH TECHNICAL POSITION RSB 5-2

%e SNUPPS plmts have been reviewed against these criteria and have-been found to have an acceptable design by use of the primary PORV's for a Low 'limperature Overpressure Protection System (LTOPS) (Wolf Creek SER Supplement #5, Section 5.2.2). When relying on the RHRS suction relief valves for L'10PS, the literal requirement of Branch Technical Position RSB 5-2 B.9 is,not met. his section states:

" If pressure relief is from a low pressure system, not normally connected to the primary system, the over-pressure protection function should not be defeated by interlocks which would isolate the low pressure system from the primary coolmt system.

(See BTP ICSB3)"

i Interlocks are provided on these valves to meet the requirements of SRP 5.4.7.

However, as shown in SNUPPS February 10, 1984 letter and as described in the bases for the Wolf Creek Technical Specifications Section B3/4.4.9 which states:

1 1

]

e

_. _ to KMIERC 85-122 2 of 4

" The OPERABILITY of two PORVs, or two RHR suction relief valves, or an RCS vent opening of at least 2 square inches ensures that the RCS will be protected from pressure transients which could exceed the limits of Appendix G to 10 CFR Part 50 when one of more of the RCS cold legs are less than or equal to 368 F. ' Either PORV or either RHR suction relief valve has adequate relieving capability to protect the RCS from overpressurization when the transient is limited to either: (1) the start of an idle RCP with the secondary water temperature of the stean

' generator less than or equal to 50 F above the RCS cold leg temperatures, or (2) the start of a centrifugal charging pump and its injection into a water-solid RCS.

RHR RCS suction isolation valves 8701A and B are interlocked with an "A" train wide range pressure transmitter and valves 8702A and B are interlocked with a "B" train wide range pressure transmitter.

Removing power from valves 8701B and 8702A, prevents a single failure from inadvertently isolating both RHR suction relief valves while maintaining RHR isolation capability for both RHR flow paths."

It is apparmt that no single failure will cause isolation of both trains and the worst cme overpressurization transient will not challenge the pressure interlock setpoint. Therefore, the intent of SRP 5.2.2 and Branch Technical Position RSB 5-2 is met.

II.

STANDARD REVIER PLAN 5.4.7 AND BRANCH TECHNICAL POSITION RSB 5-1 Brmch Technical Position RSB 5-1 Sections B.1(a) and (c) (referenced in SRP 5.4.7) state:

B.

RHR System Isolation Requirements

@e RHR system shal1 satisfy the isolation requirements 1isted below.

1.

We following shall be provided in the suction side of the RHR system to isolate it from the RCS.

(a)

Isolation shall be provided by at least two power-operated valves in series. We valve positions shall be indicated in the control room.

(b) The valves shall have independent diverse interlocks to l-protect aJainst one or both valves being open during an RCS pressure increase above the design pressure of the RHR system.

i b

i

e Attachm:nt 1 to KMLNRc 85-122 3 of 4 During the period when one valve in each train locked open as discussed in I. above, the requirements of this SRP are not met.

Wis SRP, however, did not consider use of the RHRS suction relief i

valves for LMPS. To ensure the RHRS is isolated from the RCS, administrative controls have been implemented which verify power is restored to valves BB-PV-8702A and EJ-HV-8701B and the valves are closed prior to exceeding the RHRS suction relief setpoint.

Once power is restored, the interlocks are no longer defeated and full conpliance with this SRP is re-established. Although Kansas Gas and Electric deems these controls adequate to demonstrate conpliance with the intent of RSB 5-1 and RSB 5-2 (i.e. no single failure can result in the isolation of both RHR suction relief valves, available overpressure transient initiators will not result in mtivation of the pressure interlock, and a plant procedure requires closing all RHR suction isolation valves when realigning RHR to the stmdby mode), we are proposing the design change discussed below md shown in Atta:hment 2 as a means of more fully meeting the intent of these Branch Technical Positions.

III. DESCRIPTION OF PROPOSED PLANT MODIFICATION This modification would aki an alarm circuit to valves BB-PV-8702A md EJ-HV-8701B such that if the interlock activation setpoint is reached and the valves are open or do not have power available, the alarm would initiate on the main control board. As is true for' all main control board annunciators, m annunciator alarm response procedure would be generated for this alarm. Wis procedure would require closing or verifying closure of the affected RHR suction isolation valves. W is combination of annunciator / annunciator response procedure coupled with the aiministrative controls already in place provide a more positive means of protection for the RHR system than the current design. That conclusion is based on the following items.

1.

Renoving power (defeating the interlocks) not only protects the RCS from a single failure causing isolation of both RHRS suction relief valves (loss of LMPS) but also provides protection for both RHR peps when in operation from a loss of suction due to a single pressure transmitter failure.

Inalvertent isolation of the RHR suction valves has been a concern at other plants and has resulted in danage to one RHR ptmp at Callaway. Wis concern is a3 dressed in inspection report number 50-483/84-09(DE) where the Inspector reconmended locking all RHR suction valves open in Modes 5 and 6.

2.

Althotr3h the interlocks are reliable, there is no visual indication in the control room (other than valve position indication) that the interlocks have closed the valve. % erefore, if a signal is generated to close the valve and the valve fails to close, the operator would not be alerted. With the alarm circuit installed, if the valve is open or if power is not available and the pressure setpoint is reached, an alarm is generated in the control room giving the operator positive indication. Therefore protection is afforded if the operator fails to restore power or

Attachmsnt 1 to KMLNRC 85 t2 4c 4 if the, interlock actuates and the valve fails to close.

I Additionally, alarm response procedures would provide positive operator actions.

3.-

Since it is not probable that both valves in the system would remain open and undetected during a normal startup due to other indications (i.e. relief valves 1if ting, PRT level, pressure and tenperature alarms) and since it has been shown that no credible transient would challenge the interlock setpoint, the interlock would only function to shut a valve if one valve in the train were already closed. Therefore, it is considered acceptable to use an alarm versus an' interlock since operator response time would be sufficient to prevent operation at full RCS temperature and pressure with only single valve protection for the RHR system.

IV. CONCLUSION Based on the discussions above, it is the position of Kansas Gas and Electric that reliance on.the alministrative controls with the aldition of the alarm circuits on valves BB-PV-8702A and EJ-HV-87018 not only meets the intent of SRP 5.4.7, SRP 5.2.2, RSB 5-1 and RSB 5-2, but in -

actuality provides more protection for both the RCS (LTOPS) and the RHR system than the interlocks.

1 i

_ _.. _ _. - _ _ _. _ _ _ _ _ _ _. _ _ _ _ _ _ _ _ _. _ _ _ to KMLNRC 85-122 1 of 2

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