ML20009C374

Tech Specs for Redundant Decay Heat Removal Capability, Millstone Nuclear Power Station,Unit 2, Technical Evaluation Rept

ML20009C374
Person / Time
Site:	Millstone
Issue date:	06/30/1981
From:	Decker Q, Yost M EG&G IDAHO, INC., EG&G, INC.
To:	Shemanski P Office of Nuclear Reactor Regulation
References
CON-FIN-A-6429 EGG-EA-5481, NUDOCS 8107200500
Download: ML20009C374 (19)

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TECHNICAL SPECIFICATIONS FOR REDUNDANT DECAY HEAT REMOVAL CAPABILITY, MILLSTONE NUCLEAR POWER STATION UNIT N0. 2, DOCKET N0. 50-336 s

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This is an informal report intended for use as a preliminary or working document i

C eSearC180C 661 dical Prepared for the U.S. Nuclear Regulatory Commission AssisianCe Reoort Under DOE Contract No. DE-AC07-76ID01570 FIN No. A6429 0

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FORM (G4G 398

= n rw INTERIM REPORT Accession No.

Report No.

EGG-EA-5481 Contract Program or Project Titic.;

Selected Operating Reactor Issues Program (III)

Subject of this Document:

Technical Specifications for Redundant Decay Heat Removal Capability, Millstone Nuclear Power Station, Unit No. 2 Type of Document:

Technical Evaluation Report Author (s):

• a: sner

\\ SC leS03rCh 80C "eCMiC8 Assistance Report oate o, Doc. ent:

June 1981 Responsible NRC Individual and NRC Office or Division:

Paul C. Shemanski, Division of Licensing This document was prepared primarily for preliminary or internal use. lt has not received full review and approval. Since there may be substantivo changes, this document should not bc ccr.sidered final.

EG&C :'r,%, Inc.

Idaho Falls, Idaho 83415 Prepared for the U.S. Nuclear Regulatory Commission Washington, D.C.

Under DOE Contract No. DE-AC07 761DC1570 NRC FIN No.

A6429 INTERIM REPORT

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L' TECHNICAL SPECIFICATIONS FOR REDUNDANT DECAY HEAT REMOVAL CAPABILITY MILLSTONE NUCLEAR POWER STATION, UNIT N0. 2 i

Docket No. 50-336 l

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June 1981 7

M. W. Yost Q. R. Decker 4

Reliability and Statistics Branch Engineering Analysis Division EG&G Idaho, Inc.

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TAC No. 42112

ABSTRACT In response to D. G. Eisenhut letter dated June 11, 1980, Northern Utilities submitted " Proposed Revisions to Technical Specifications" for the Millstone Nuclear Power Station, Unit No. 2.

These proposed revisions would provide for redundancy in decay heat removal capability in :li modes of operation.

After review of the proposed revisions, it is concluded that they assure redundant decay heat removal capability in all operating mc %s.

FOREWORD This report is supplied as part of the " Selected Operating Reacter Issues Program (III)" being conducted for the U.S. Nuclear Regulatory Commission, Office of Nuclear Reactor Regulation, Division of Licensing, by EG&G Idaho, Inc., Reliability and Statistics Branch.

The U.S. Nuclear Regulatory Commission funded the work under the authorization, B&R 20 19 01 06, FIN No. A6429.

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CONTENTS

1.0 INTRODUCTION

l 2.0 REVIEW CRITERIA...................................................

I 3.0 DISCUdSIONS AND EVALUATION........................................

2 3.1 Startup and Power Operations.................................

2 3.2 Hot Standby..................................................

2 3.3 Shutdown.....................................................

3 3.4 Refueling....................................................

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4.0 CONCLUSION

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5.0 REFERENCES

4 APPENDIX A--NRC MODEL TECHNICAL SPECIFICATIONS.........................

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TECHNICAL EVALUATION REPORT TECHNICAL SPECIFICATIONS FOR REDUNDAh3 DECAY HEAT 71M0 VAL CAPABILITY MILLSTONE NUCLEAR POWER STATION, UNIT NO. 2

1.0 INTRODUCTION

A number of events have occurred at operating PWR facilities where decay

' heat removal capability has been seriously degraded due to inadequate admin-istrative controls during shutdown modes of operation. One of these events, described in IE Information Notice 80-20,I occurred at the Davis-Besse, Unit No. 1 plant on April 19, 1980.

In IE Bulletin 80-122 dated May 9, 1980 licensees were requested to immediately implement administrativt con-trols which would ensure that proper means are available to provide redundant methods of decay heat removal. While the function of the bulletin was to effect immediate action with regard to this problem, the NRC considered it necessary that an amendment of each license be made to provide for permanent long term assurance that redundancy in decay heat removal capability will be maintained.

By letter dated June 11, 1980,3 all PWR licensees were requested to propose technical specification (TS) changes that provide for redundancy in decay heat removal capability in all modes of operation; use the NRC model TS which provide an acceptable solution of the concern and include an appropriate safety analysis as a basis; and submit the proposed TS with the basis by October 11, 1980.

Northeast Util' ties (NU), Hartford, Connecticut, submitted proposed revisions for decay heat removal to their Technical Specifications (TS) for Millstone Nuclear Power Station, Unit No. 2,4 on October 17, 1980.

2.0 REVIEW CRITERIA The review criteria for this task are contained in the June 11, 1980 letter from the NRC to all PWR licensees. The NRC provided the model tech-nical specifications (MTS) which identify the normal required redundant coolant system and the required actions when redundant systems are not available for a typical four loop plant (Appendix A).

The general review criteria are:

1.

Two independent methods for decay heat removal are required in the plant TS for each operating mode.

2.

Periodic surveillance requirements should insure tne operability of the systems.

ThespecificsgctionsoftheCombustionEngineeringStandardTechnical Specifications that apply to this task are as follows:

3/4.4 Reactor Coolant System 3/4.4.1 Reactor Coolant System and Coolant Circulation 1

4 Startup and Power Operation (modes 1 & 2)

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3.4.1.1 Limiting Conditions for Operation 4.4.1.1 Surveillance Requirements Hot Standby (mode 3) 3.4.1.2 Limiting Conditions for Operation 4.4.1.2.1 Surveillance Requirement 4.4.1.2.2 Surveillance Requirement Shutdown (modes 4 & 5) 3.4.1.3 Limiting Conditions for Operation 4.4.1.3.1 Surveillance Requirement 4.4.1.3.2 Surveillance Requirement 4.4.1.3.3 Surveillance Requirement 4.4.1.3.4 Surveillance Requirement Refueling Operations (mode 6) 3.9.8.1 Limiting Condition for Operation 3.9.8.2 Limiting Condition for Operation 4.9.8.1 Surveillance Requirement 4.9.8.2 Surveillance Requirement 3.0 DISCUSSION AND EVALUATION Arkansas Nuclear One, Unit No. 2, is a two loop Combustion Engineering (CE) PWR plant. Due to plant design the proposed TS for this plant vary f rom the NRC model developed from Westinghouse standard TS. The minor differences were determined to be agreeable with the NRC model technical specifications. The evaluations of the AP&L proposed TS are as follows:

3.1 Startup and Power Operation--Modes 1'and 2 The proposed TS require that both reactor coolant loops and,oolant pumps are to be operational.

If these conditions are not met, the reactor is to be in Hot Standby (Mode 3) within i hour.

The proposed TS require verification that the required reactor coolant loops are in operation at least once per 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.

The above described proposed TS are in agreement with the MTS since two coolant loops are required and the periodic surveillance assures the i

operability of the systems.

3.2 Hot Standby--Mode 3 The proposed TS require two coolant loops and at least one associated coolant pump for each loop shall be operable a and at least one of the i

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Coolant loops shall oe in operationa during this operating mode; and the i

proposed TS require the plar.t to be in Hot Shutdown (Mode 4 & 5) in 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> if the two coolant loops are not operable and cannot be restored to operable r

status in 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />, suspend ali operations involving a reduction in boron

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concentration in the coolant system and initiate corrective action to return the coolant loop to operation. Proposed TS require verification that at least one coolant pump is operable once per 7 days and at least one cooling loop is in operation at least once per 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.

Because of the requirement to have two coolant loops and one coolant pump per loop operable and assurance of operability through periodic sur-veillance the above proposed TS meet the requirements of the MTS.

3.3 Shutdown--Modes 4 & Sb The proposed TS satisfy the requirements for the shutdown modes by having at least two coolant loops operable from either the two reactor coolant loops (including at least one of their associated coolant pumps and their associated steam generators) or the two shutdown coolant loopsc to i

be in operable status,dand requiring that at least one of the four coolant loops be in operation.

If this criteria is not met and immediate cor-rective ac'. ion does not restore the loop (s) to operable or operational status, the reactor is to be in Cold Shutdown within 20 hours2.314815e-4 days <br />0.00556 hours <br />3.306878e-5 weeks <br />7.61e-6 months <br /> and reduction of boron concentration operations are to be suspended.

The requirements for this mode of operation are met by requiring two coolant loops and associated pumps to be opeiable with one of the to 1

operating. Operation and operability of the loops is required to be verified periodically.

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a.

All reactor coolant pumps may be de-energized for up to 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> provided (1) no operations are permitted that would cause dilution of the reactor coolant system boron concentration, and (2) core outlet temperature is j

maintained at least 100F below saturation temperature, f

b.

A reactor coolant pump shall not be started with one or more of the RCS I

cold leg temperatures less than or equal to 2750F unless:

(1) the l

pressurizer water volume is less than 600 cubic feet or (0) the secondary 2

water temperature of each steam generator is less than 43 F (310F when l

f measured by a surf ace contact instrument) above each of the RCS cold leg temperatures.

c.

The normal or emergency power source may be inoperable in MODE 5.

d.

All reactor coolant pumps and shutdown cooling pumps may be de-energized for up to I hour provided:

(1) no operations are permitted that would cause dilution of the reactor c]olant system boron concentration, and (2) core outlet temperature is maintained at least 100F below saturatien temperature.

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i 3.4 Refueling--Mode 6 The proposed TS for this mode states that the limiting condition for i

operation is for all water levels and requires at least one shutdown cool-l ing loop to be in operation.

If less than one shutdown cooling loop is in operation, except for the provision to alter the core configuration without the curling loop in operation, all operations that would increase the deccy heat load or boron reduction of the reactor coolant system are to be sus-pended. All containment penetrations that allow direct inside to outside atmosphere accesses are to be closed in 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />. At least one shutdown cooling loop circulating coolant at a flow rate of 3000 gpm shall be verified in operation at least once per 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />.

The proposed TS require ti.at in the refueling mode with the water level less than 23 feet above the reactor pressure vessel flange, correc-tive action to return the required loop (s) to operable status is initi-t ated immediately, if either of the shutdown cooling loops are determined inoperable. The required shutdown cooling loop (s) shall be determined operable once per 7 days.

The proposed TS agree with the MTS requiring at least two cooling loops be operable and surveillance provided to assure their operability.

4.0 CONCLUSION

An evaluation of the proposed TS for Millstone Nuclear Power Station, Unit No. 2, inJicates that they provide adequate decay heat removal capa-bility in all operating modes and also provide redundancy with respect to single failure considerations.

5.0 REFERENCES

I 1.

NRC IE Information Notice 80-20, May 8, 1980.

2.

NRC IE Bulletin 80-12, May 9, 1980.

3.

NRC Letter, Darrell G. Eisenhut, To All Operating Pressurized Water Reactors (PWR's), June 11, 1980.

4.

NU Letter, W. G. Counsil to NRC, Darrell G. Eisenhut, October 17, 1980.

5.

Standard Technical Specifications for Combustion Engineering Pres-surized Water Reactors, NUREG-0212, Rev.1, Fall 1980.

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APPENDIX A MODEL TECHNICAL SPECIFICATIONS FOR REDUNDANT DECAY HEAT REMOVAL FOR ALL PRESSURIZED WATER REACTORS (PWR's)

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3/4.4 REACTOR COOLANT SYSTEM

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3/4.4.1 REACTOR COOLANT LOOPS AND C00LAdT CIRCULATION STARTUP AND POWER OPERATION LIMITING CONDITION FOR OPERATION 3.4.1.1 All reactor coolant loops shall be in operation.

APPLICABILITY: MODES 1 and 2.*

ACTION:

With less than the above required reactor coolant loops in operation, be in at least HOT STANDBY within I hour.

SURVEILLANCE REQUIREMENT 4.4.1.1 The above required reactor coolant loops shall be verified to be in operation and circulating reactor coolant at least once per 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.

See Special Test Exception 3.10.4.

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REACTOR COOLANT SYSTEM HOT STANDBY LIMITING CONDITION FOR OPERATION 3.4.1.2 a.

At least two of the reactor coolant loops listed below shall be OPERABLE:

1.

Reactor Coolant Loop (A) and its associated steam generator and reactor coolant pump, 2.

Reactor Coolant Loop (B) and its associated steam generator and reactor coolant pump, 3.

Reactor Coolant Loop (C) and its associated steam generator and reactor coolant pump, 4.

Reactor Coolant Loop (D) and its associated steam generator and reactor coolant pump.

b.

At least one of the above coolant loops shall be in operation.*

APPLICABILITY: MODE 3 ACTION:

a.

With less than the above required reactor coolant loops DIERABLE, restore the required loops to OPERABLE status within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> or be in HOT SHUTDOWN within the next 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.

All reactor coolant pumps may be de-energized for up to I hour provided (1) no operations are permitted that would cause dilutica of the reactor coolant system boron concentration, and (2) core outlet temperature is maintained at least 100F below saturation temperature.

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With no reactor coolant loop in operation, suspend all operations involving a reduction in boron concentration of the Reactor Coolant System and immediately initiate corrective action to r

return the required coolant loop to operation.

l SURVEILLANCE REQUIREMENT 4.4.1.2.1 At.least the above required reactor coolant pumps, if not in operation, shall be determined to be OPERABLE once per 7 days by verifying correct breaker alignments and indicated power availability.

I 4.4.1.2.2 At least one cooling loop shall be verified to be in operation and circulating reactor coolant at least once per 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.

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REACTOR COOLANT SYSTEM

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SheruWH LIMITING CONDITION FOR OPERATION 3.4.1.3 a.

At least two of the coolant loops listed below shall be i

OPERABLE:

1.

Reactor Coolant Loop (A) and its associated steam gen-erator and reactor coolant pump,*

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Reactor Coolant Loop (B) and its associated steam gen-erator and reactor coolant pump,*

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Reactor Coolant. Loop (C) and its. associated steam gen-erator and reactor coolant pump,*

4.

Reactor Coolant Loop (D) and its associated steam gen-erator and reactor coolant pump,*

5.

Residual Heat Removal Loop (A),*=

6.

Residual Heat Removal Loop (B).**

b.

At least one of the above coolant loops shall be in operation.***

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A reactor coolant pump shall not be started with one or more of the RCS cold leg temperatures less than or equal to (275)0F unless 1) the pressurizer water volume is less than cubic feet or 2) OF above each the secondary water temperature of cach steam generator is less than of the RCS cold leg temperatures.

I The normal or emergency power source may be inoperable in MODE 5.

All reactor coolant pumps and decay heat removal pumps may be de-energized for up to I hour provided 1) no operations are permitted that would cause dilution of the reactor coolant system boron concer.tration, and

2) core outlet temperature is maintained at least 100F below saturation temperature.

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REACTOR COOLANT SYSTEM APPLICABILITY: MODES 4 and 5.

ACTION:

' ith less than the above required loops OPERABLE, immediately a.

initiate corrective action to return the required loops to OPERABLE status as soon as possible; be in COLD Sh0T00WN within 20 hours2.314815e-4 days <br />0.00556 hours <br />3.306878e-5 weeks <br />7.61e-6 months <br />, b.

With no coolant loop in operation, suspend all operations involving a reduction in boron concentration of the Reactor Coolant System and immediately initiate corrective action to return the required coolant loop to operation.

SURVEILLANCE REQUIREMENT l

4.4.1.3.1 The required retidual heat removal loop (s) shall be determined OPERABLE per Specification 4.0.5.

4.4.1.3.2 The required reactor coolant pump (s), if not in operation, shall be determined to be OPERABLE once per 7 days by verifying correct breaker alignments and indicated power availability.

i 4.4.1.3.3 The required steam generator (s) shall be determined OPERABLE by verifying secondary side level to be greater than or equal to (

)% at least once per 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.

4.4.1.3.4 At least one coolant loop shall be verified to be in operation and circulating reactor coolant at least once per 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.

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REFUELING'0PERATIONS'

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3/4.9.8 RESIDUAL HEAT REMOVAL AND COOLANT CIRCULATION ALL WATER LEVELS LIMITING CONDITION FOR OPERATION i

3.9.8.1 At least one residual heat removal (RHR) loop shall be in operation.

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APPLICABILITY: MODE 6 ACTION:

f a.

With less than one residual heat removal loop in operation, except as provided in b. below, ruspend all operations involving an increase in the reactor decay heat load or a reduction in boron concentration of the Reactor Coolant System. Close all containment penetrations providing direct access from the con-

'tainment atmosphere to the outside atmosphere within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />.

b.

The residual heat removal loop may be removed from operation for up to I hour per 8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> period during the performance of CORE ALTERATIONS in-the vicinity of the reactor pressure vessel (hot) legs.

c.

The provisions of Specification 3.0.3 are not applicable.

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4.9.8.1 At least one residual heat removal loop shall be verified to be in l.

. operation and circulating reactor conlant at a flow rate of greater than or l

equal to (2800) gpm at least once per 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />.

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REFUELING OPERATIONS LOW WATER LEVEL LIMITING CONDITION FOR OPERATION 3.9.8.2 Two independent Residual Heat Removal (RHR) loops shall be OPERABLE.*

APPLICABILITY: MODE 6 when the water level above the top of the irradiated fuel assemblies seated within the reactor pressure vessel is less than 23 feet.

ACTION:

a.

With less than the required RHR loops OPERABLE, immediately initiate corrective action to return the required RHR loops to OPERABLE status as soon as possible.

b.

The provisions of Specification 3.0.3 are not applicable.

SURVEILLANCE REQUIREMENT 4.9.8.2 The required Residual Heat Removal loops shall be determined OPERABLE per Specification 4.0.5.

J Tae normal or emergency power source may be inoperable for each RHR loop.

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4 3/4.4 REACTOR COOLANT SYSTEM i

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3/4.4.1 REACTOR COOLANT LOOPS AND COOLANT CIRCULATION The plant is designed to operate with all reactor coolant-loops in operation, and maintain DNBR above 1.30 during all normal operations and anticipated transients.

In MODES 1 and 2 with one reactor coolant loop not in operation this specification requires that.the plant be in at least HOT i

STANDBY within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />.

1 In MODE 3, a single reactor coolant loop provides sufficient heat removal capability for removing decay heat; however, single failure con-siderations require that two loops be OPERABLE.

i In MODES 4 and 5, a_ single reactor coolant loop or RHR loop provides sufficient heat removal capability for removing decay heat; but single failure considerations require that at least two loops be OPERABLE. Thus, if the reactor coolant loops are not OPERABLE, this specification requires two RHR loops to be OPERABLE.

The operation of one Reactor Coolant Pump er one RHR pump provides adequate flow to ensure mixing, prevent str;Lification and produce gradual reactivity changes during boron concentration reauctions in the Reactor Coolant System.

The reactivity change rate associated with boron reduction will, therefore, be within the capability of operator recognition and control.

The restrictions on starting a Reactor Coolant Pump with one or more RCS ccid legs less than or equal to (275)0F are provided to prevent RCS pressure transients, caused by energy additions from the secondary system, which cauld exceed the limits of Appendix G to 10 CFR Part 50.

The RCS will be protected against overpressure transients and will not exceed the limits of Appendix G by either (1) restricting the water volume in the q

pressurizer and thereby providing a volume for the primary coolant to expand into, or (2) by restricting starting of the RCPs to when the secon-dary water temperature of each steam generator is less than (

)0F above each of the RCS cold leg temperatures.

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REFUELING OPERATION _S BASES l

j 3/4.9.8 RESIDUAL HEAT REMOVAL AND C00.. ANT CIRCULATION The requirement that at least one residual heat removal (RHR) loop be in operation ensures that (1)' sufficient cooling capacity is available to remove decay heat and maintain the water in the reactor pressure vessel below 140 F as required during the REFUELING MODE, and (2) sufficient cool-ant circulation is maintained through the reactor core to minimize the i

effect of a boron dilution incident and prevent boron stratification.

I The requirement to have two RHR loops OPERABLE when there is less than 23 feet of water above the core ensures that a single failure of the oper-ating RHR loop will not result in a complete loss of residual heat removal capability. With the reactor vessel head removed and 23 feet of water above the core, a large heat sink is available for core cooling. Thus, in the event of a failure of the operating RHR loop, adequate time is provided to initiate emergency procedures to cool the core.

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