ML20011F014

Proposed Tech Specs Re Limiting Conditions for Operation & Surveillance Requirements for Automatic Depressurization Sys Valves

ML20011F014
Person / Time
Site:	Peach Bottom
Issue date:	02/14/1990
From:	PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To:
Shared Package
ML20011F011	List: ML20011F010 ML20011F014
References
NUDOCS 9002230446
Download: ML20011F014 (8)

Text

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-ATTACHMENT 2' 4

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Docket No. 50-277 n <

License No.-DPR-44 z,

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.m ' TECHNICAL SPECIFICATION CHANGE t

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LIMITING CONDITIONS FOR OPERATION SURVEILLANCE REQUIREMENT , 3.5.E Automatic Depressurization 4.5.E Automatic Depressurization System (ADS) f System (ADS) l

-1. The AutomaticcDepressuriza- 1. During each operating cycle

' tion Subsystem shall be oper- the following tests shall -

able whenever there is irra- be performed on the ADS: '

diated fuel in the reactor t vessel and the reactor pres- A simulated automatic actu-sure is greater than 105 psig ation test shall be per -

and prior to a startup from a formed prior to startup af- ,

Co.1d condition, except as ter each refueling outage.

specified in 3.5.E.2 below. .

t From arid af ter the date that

2. 2. When it is determined that one valve in the automatic one valve of the ADS is in-depressurization subsystem is operable, the ADS subsystem made or found to be inoper- actuation logic for the

_ able for any reason, conti- other ADS valves and the -

nued reactor operation is HPCI subsystem shall be  ;

permissible only during the demonstrated to be operable - 1 succeeding seven days *unless immediately and at least such valve is sooner made weekly thereafter.

operable, provided that dur-

, ing such seven

• days the HPCI subsystem is operable.

3. If the requirements of 3.5.E .

cannot be met, an orderly '

shutdown shall be initiated and the reactor pressure shall be reduced to at least 105 psig within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. .,

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• This seven-day LCO has a one-time extension to 11:59 p.m. on March 3, 1990 provided RCIC is operable.

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< . l NUCLEAR ENGINEERING ENGINEERING DIVISION ,

63B-3, 965 Chesterbrook Boulevard l l

10CFR50.59' REVIEW TEMPORARY TECH. SPEC. CHANGE FOR  !

AUTOMATIC DEPRESSURIZATION SYSTEM (ADS) ,

LIMITING CONDITION FOR OPERATION (LCO) EXTENSION j Peach Bottom Atomic Power Station, Unit 2 i Revision 0 '

I. ' SUBJECT i This temporary Tech. Spec. Change will allow continued  !

operation of Peach Bottom Unit 2 with one ADS valve inoperable until the' planned mid-cycle outage beginning March 3, 1990  ;'

.provided the RCIC System remains operable. The existing LCO of 7 days expires on February 14, 1990.-  :

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II. 50.59 DETERMINATION i

This proposed temporary Tech. Spec. changet t

1. Docs require a change to the Tech. Specs. . A temporary change is recommended to Tech. Spec.

3.5.E-to extend the ADS LCO period to March 3, 1990.

2. Does not change the facility as described in the SAR.

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3. Docs not require a change to the procedures as described in the SAR. .

4. Does not involve tests or experiments not described e in the SAR. .;

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III. 50.59 SAFETY EVALUATION A. Accidents previously evaluated in the UFSAR are discussed in Section 14.0 and Appendix G >

1. The probability of occurence.of an accident previously evalcated will not be increased. Having one ADS valve out of service is not related to any initiating sequence of an accident scenario.

2. The consequences of an accident previously evaluated in the SAR will not be increased. The existing condition with four ADS valvos operable with low pressure Core Standby Cooling Systems (CSCS) in conjunction with High Pressure Coolant Injection (HPCI) allows for single-failure proof core cooling for intermediate and small break LOCA's.

3. The possibility of an accident of a different type than any previously evaluated in the SAR is not created. Ability to achieve core cooling during small and intermediate break LOCA's is not affected, and therefore the possibility of a different type of accident is not created.

B. Equipment important to safety that is potentially impacted is the ADS.

1. The probability of occurrence of a malfunction of equipment important to safety previously evaluated in the SAR will not be increased. One inoperable ADS valve does not affect the operability of the four remaining ADS valves.

2. The consequences of a malfunction of equipment important to safety previously evaluated in the SAR will not be increased. SAR LOCA analyses were based on maintaining 4 ADS valves operable. In addition, Safe Shutdown will also be assured even with the K valvo inoperable because for Safe Shutdown method D, only 2 of the 3 provided SRV's '

are required. Calculation ME-384 has determined that only 2 SRV's are required for a low pressure CSCS to remove decay heat after reactor shutdown.

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3. The possibility of a different type of malfunction

, of equipment important to safety than any

(= previously evaluated in the SAR will not be created. A single ADS valve out of service has already been evaluated-in the SAR. The failure mode of the inoperable ADS valve (i.e., an electrical open circuit) does not interfere with the pressure relief valve function.

F C. The proposed change does not reduce the margin of

(, safety as defined in the bases of Tech. Specs. The current LOCA analysis assumes 4 ADS valves are operable. The largo break LOCA Peak Clad Temperature (PCT) margin is unchanged since the ADS does not initiate during this secnario. The small and intermediate break PCT margin is unchanged since 4 ADS valves are operable. The current small and

> intermediate break PCT is on the order of 1500 F, (Reference 1) which is significantly below the 2200 F PCT limit. In addition, if another ADS valve, HPCI or RCIC becomes inoperabic, nn orderly shutdown will be initiated por Tech. Spec. 3.5.E.3.

D. 10CFR50.59 Safety Evaluation

Conclusion:

Based on abovo Section III, Parts A through C, the proposed Tech. Spec. change does not involve an unroviewed safety question.

g 2V. DISCUSSION Dackground Toch. Specs. 3/4.5.E state that "when it is-determined that

- one valvo of the ADS is inoperabic, the ADS subsystem actuation logic for the other ADS valves and the HPCI subsystem shall be demonstrated to be operable immediately and at least weekly thereafter". If the inoperable valvo cannot be restored within the subscquent seven days or if HPCI or another ADS valve becomes inoperable during that timo period, an orderly shutdown of the L unit must bo initiated.

Logic testing of the ADS valves indicated that the solenoid of.the "K" ADS valve on' Unit 2 was inoperabic because of an open circuit. This open circuit prohibits both automatic and manual actuation of the valvo. However, the pressure relief function is s

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still available. The remaining ADS valves and the HPCI syctem l t were subsequently determined to be operable. The open circuit in ,

the K solenoid has been determined to be located insido primary l l

containment, and therefore cannot be repaired while the unit is in operation. A Unit 2 mid-cycle outage is scheduled to begin on l March 3, 1990 for planned maintenance activitics. j L This evaluation supports continued operation with 4 of the 5 j ADS-valves operable until the planned mid-cycle outage, with the <

additional requirement that the Reactor Corc Isolation Cooling )

(RCIC) System be maintained operabic. Without this variance, onc l outago.would be required beginning February 14 to repair the ADS j valve, with the mid-cycle outage to follow on March 3. I Unit 2 is prcsontly limited to nominal 74% power until the mid-cycle outage because of feedwater heater tubo leaks. In no case will power be allowed to exceed 80% during normal operation l prior to the mid-cycle outage. ]

Evaluation l

From a licensing design basis point of view, the Peach i Bottom UFSAR was reviewed for ADS valve and system operability j requirements. In particulr.r, the Plant Nuclear Safety l Operational Analyses contained in Appendix G details the maximum number of ADS valves which are required to safely shutdown the l plant under various accident scenarios. The most limiting 1 condition requiring ADS actuation, a small break LOCA, requires that the following single-failure proof network be available:

the HPCI system (which is not a single-failure proof system), or the ADS in conjunction with low pressure CSCS. In this case, a maximum of 4 ADS valves are required to be operable (Reference UFSAR Figure G.5.20). Therefore, as long as 1) the HPCI system ,

is operable, or 2) four ADS valves with low pressure CSCS are operable, then a success path through the sing 1c-failure proof network is available. Confirmation of the four-valvo design basis is provided in UFSAR Section 6, where ADS is described as having five 25% capacity valves.

From an analytical point of view, the bases for the Emergency Procedurc Guideline (EPG) calculations were reviewed. ,

EPG Rev. 3 calculations used best estimate methods presented in NEDO-24708 (Reference 3), and determined that only 3 SRV's werc

' required to safely depressurlac the reactor while maintaining peak cladding temperature below 2200 F. NEDO-24708 was reviewed and accepted by the NRC. The EPG's provide the basis for the Transient Response Implementation Plan (TRIP) procedures. TRIP procedures require manual actuation of 3 SRV's for emergency blowdown. PRA analyses require only 2 operable ADS valves, and take credit for the manual actions required in the TRIP procedures.

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In addition, Unit 2 is presently operating at restricted power lovcis because of feedwater heater tube leaks. The current LOCA analysis calculates a PCT on the order of 1500 F for a small

, break LOCA. The analysis. assumes MAPRAT equals 1.0 at the L initiation of the analysis. Changes in MAPRAT of 15% result in changes in PCT of approximately 150 F. Since Unit 2 will be operating with MAPRAT < 0.8 (a 20% reduction) due to reduced upower level, the PCT for the small break LOCA will decrease by L greater than 150 F to less than 1350.F. Thorofore, significant margin (i.e. minimum of 850 F) to the PCT limit of 2200 F cxists in the current LOCA analysis with reduced power level.

L Concurrence with this conclusion was obtained from GE as stated in Reference 2.

I The Unit 2 Toch. Spec. Bases acknowledge that with one ADS valve inoperable, the remaining four valves will perform their ADS function. The bases also state that LOCA analyses for small pipe line breaks assumes that all 5 ADS valves are operable.

Five ADS valves are an input into the LOCA analysis; however, one valve is assumed out of service. Thorofore, the analysis actually relics on only 4 ADS valves being operable. The Bases reference UFSAR Section 6 and Appendix G. As stated above, Section 6 describes five 25% capacity ADS valves, and Appendix G analyses require that a maximum of 4 ADS valvos be operabic for the small break LOCA scenario. It should be noted that the Unit 3 Tech. Spec. Bases state that, although the ADS contains 5 valves, LOCA analyses are based on four.

l The Safe Shutdown Analysis, in.the Fire Protection Plan (FPP), _ indicates-that a fire occurring in the control room, the

. cable spreading room, the computer room, or the emergency shutdown pancl area has the potential to prevent safe shutdown from the control room. Therefore, safe shutdown method D was developed in the FPP to handle this type of occurrence. In this method, four alternate control stations were developed: 1) HPCI Alternato Control Station (ACS), 2) Emergency Switchgear ACS,

3) Dioscl Generator ACS, and 4) ADS ACS. HPCI and ADS ACS features include throc SRV's (A, B, and K). In this case, the K relief valve is inoperable; therefore leaving two available relief valves. After reviewing this method, it was determined that with two ADS valves operable, safe shutdown is assured due to the following:

1. If safe shutdown method D is required, HPCI is availabic_to provide inventory makeup during the reactor depressurization and the two remaining relief valves are capable of depressurizing the reactor.

2. Calculation ME-384 has determined that only two SRV's are required for a low pressure CSCS to remove decay heat after reactor shutdown.

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- - In summary, the above discussion supports the conclusion that one inoperable ADS valvo does not compromise plant safety.

This condition moots design basis critoria, and is bounded by previously analyzed depressurization scenarios. The additional requirement to maintain the RCIC System operable supplements core cooling capability with the reactor at high pressures. If another ADS valve, HPCI or RCIC becomes inoperable, an orderly shutdown will be initiated per Tech. Spec. 3.5.E.3.

L This temporary Tech. Spec. change does not affect combustible loads at the plant or interfere with fire protection I' systems; therefore, a Fire Protection Review Checklist is not

f. required. No ALARA concerns are being created; therefore, an ALARA Review Checklist is not required. Radwasto sys. cms are unaffected; therefore, the guidance provided in I.E. Circular

! 80-18 is not applicabic.

V.

SUMMARY

The proposed temporary Toch. Spec. Change:

L a. does affect safety-related equipment.

b. does not involve an unroviewed safety question.

c. does require a temporary Tech. Spec. change.

d. does maintain the capability to safely shut down the plant in the event of a fire,

c. does require a license amendment or prior NRC approval.

f. does not involve a significant hazards determination.

VI. 10CFR50.92 SIGNIFICANT HAZARDS DETERMINATION This review is not applicabic since an unroviewed safety question does not exist.

REFERENCES

1. " Loss of Coolant Accident Analysis for Peach Bottom Atomic Power Station Unit 2", NEDO 24081, December, 1977.

2. Letter from D. C. Sarell/D. A. Harmon (GE) to M. P.

Gallagher (PECO) dated February 13, 1990; " Peach Bottom Unit 2 LOCA Response with One ADS Valve Out of Service" 3.- " Additional Information Required for NRC Staff Generic Report on Boiling Water Reactors", NEDO 24708A Revision 1, December, 1980.