ML20039G405

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Tech Specs for Redundant Decay Heat Removal Capability, Millstone Nuclear Power Station,Unit 2.
ML20039G405
Person / Time
Site: Millstone Dominion icon.png
Issue date: 12/30/1981
From: Decker Q, Steverson J, Yost M
EG&G, INC.
To: Donohew J
Office of Nuclear Reactor Regulation
References
CON-FIN-A-6429 EGG-EA-5481, NUDOCS 8201180169
Download: ML20039G405 (15)
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W This is an informal report intended for use as a preliminary or wo king document Prepared for the U.S. Nuclear Regulatory Commission Under DOE Contract No. DE-AC07-76ID01570 FIN No. A6429 U E5cG ,s,n.

8201180169 811230 PDR RES 8201180169 PDR l

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hEGaG...n FORM EG4G-398 tRev 1179)

INTERIM REPORT Accession No.

Report No. EGG-EA-5481, Rev. 2 C:ntract Program or Project

Title:

Selected Operating Reactor Issues Prcgram (III)

  • Su! ject of this Document:

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

Technical Evaluation Report Author (s):

Q. R. Decker, M. W. Yost, J. A. Steverson Dr.ta of Document:

December 1981 RIsponsible NRC Individual and NRC Office or Division:

J. N. Donohew, Division of Licensing This document was prepared primarily for preliminary orinternal use. it has not received full review and approval. Since there ma/ be substantive changes, this document should not be considered final.

EG&G Idaho, Inc.

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

Under DOE Contract Mo. DE-AC07-761001570 NRC FIN No. A6429 INTERIM REPORT

0403J TECHNICAL SPECIFICATIONS FOR REDUNDANT DECAY HEAT REM 0'!AL CAPABILITY MILLSTONE NUCLEAR POWER STATION, UNIT NO. 2 Docket No. 50-336 December 1981 Q. R. Decker M. W. Yost J. A. Steverson Reliability and Statistics Branch Engineering Analysis Division EG&G Idaho, Inc.

TAC No. 42112

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ABSTRACT  !

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! This report reviews the Arkansas Nuclear One, Unit No. 2 Technical l Specification requirements for redundancy in decay heat removal capability  ;

l in all modes of operation.

FOREWORD l l  :

This report is supplied as part of the " Selected Operating Reactor l 4 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 I l authorization, B&R 20 19 bl 06, FIN No. A6429. l 1  ;

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l CONTENTS  :

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. INTRODUCTION ......................................................- - l i i

!' 2.0 ' REVIEW CRITERIA ................................................... 1 i

. 3.0 DISCUSSIONS AND EVALUATION ........................................ 2 [

1 3.1 Startup and Power Operations ................................. 2 [

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

3.3 Shutdown ..................................................... 3 i 3.4 Refueling .......................................,............ 3

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4.0 CONCLUSION

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5.0 REFERENCES

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, APPENDIX A--NRC MODEL TECHNICAL SPECIFICATIONS ......................... 5

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TECHNICAL EVALUATION REPORT  ;

TECHNICAL SPECIFICATIONS FOR REDUNDANT DECAY HEAT REMOVAL CAPABILITY MILLSTONE NUCLEAR POWER STATION, uhli NO. 2

1.0 INTRODUCTION

A number of events have occurred at operating PWR facilities where decay i heat removal capability has been seriously degraded due to inadequate admin- '

, istrative controls during shutdown modes One of these events, described in IE Information Notice 80-20,gfoccurred operation.

at thq Davis-Besse, Unit No. I plant on April 19, 1980. In IE Bulletin 80-124 dated May 9, i 1980 licensees were requested to imediately implement administrative con-  !

trols which would ensure that proper means are available to provide recundant 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 ce made to provide for permanent longtermassurancethatredundancyindecagheatremovalcapabilitywillbe maintained. By letter dated June 11, 1980, all PWR licensees were requested to propose tecnnical 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 i include an appropriate safety analysis as a basis; and submit the proposed TS with the basis by Octcber 11, 1980.

Northeast Utilities (NU), Hartford, Connecticut, submitted proposed i revisions for decay heat removal to their Te i MillstoneNuclearPowerStation,UnitNo.2,ghnicalSpecifications(TS)for on October 17, 1980.

l 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 tne 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 two loop Combustion Engineering plant (Appendix A). l This review will determine if the licensees existing and/or proposed plant

TS are in agreement with the NRC MTS.

l The specific sections of the Combustion Engineering Standard Techn', cal f 4 Specifications 5 that apply to this task are as fpilows:  ;

f 3/4.4 Reactor Coolant System 3/4.4.1 Reactor Coolant System and Coolant Circulation Startuo and Power Operation (modes 1 & 2)  !

3.4.1.1 Limiting Conditions for Operation  !

4.4.1.1 Surveillance Requirements  ;

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Hot Standby (mode 3) [

3.4.1.2 Limit'qg Conditions for Operation 4.4.1.?.1 Surveillance Requirement 1

4.4.1.2.2 Surveillance Requirement Shutdawn (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 , l 4.4.1.3.4 Surveillance Requirement l 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

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Millstone Unit No. 2, is a two loop Combustion Engineering (CE) PWR plant. The following discussion presents an evaluation of the proposed technical specifications submitted by AP&L for redundant decay heat removal as raquested by the NRC.

3.1 Startup and Power Operation--Modes 1 and 2 The proposed TS require that both reactor coolant loops and coolant pumps are to be operational. If these conditions are not met, the reactor is to be in Hot Standby (Mode 3) within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />. 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 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 and at least one of the coolant loops shall be in operation during this operating mode:a and the proposed '

TS require the plant 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 status

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

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

I 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 & 5a The proposed T5 satisfy the requiremcnts 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 loops b to be in operable status, and requiring that at least one of the four coolant loops be in operation.c If this criteria is not met and immediate cor-rective action 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 oper,ations are to be suspended.

a The requirements for this mcde of operation are met by requiring two coolant loops and associated pumps to be operable with one of the two oper-l ating. Operation and operability of the loops is required to be verified periodically.

3.4 Refueling--Mode 6 The proposed TS for this mode states that the limiting condition for operation is for all water levels and requires at least one shutdown cool-in; loop to be in operation. If less than one shutdown cooling loop is in ,

operation, exceot for the provision to alter the core configuration without the cooling loop in ooeration, all operations that would increase the decay 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 ar6 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

a. A reactor coolant pump shall not be started with one or more of the RCS cold leg temperatures less thaq or equal to 275 F unless: (1) the pressurizer water volume is less than 600 cubic feet or (2) the secondary water temperature of each steam generator is less than 430F (310F when measured by a surface contact instrument) above each of the RCS cold leg temperatures.

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b. The normal or emergency power source may be inoperable in MODE 5.
c. 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 coolant system boron concentration, and (2) core outlet temperature is maintained at least '

10 F below saturation temperature.

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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 that 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 operchle status is initi-ated i nmediately, it aither of the shutdown cooling locos 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, indicates that they are in conformance with the MTS for redundant decay heat removal.

5.0 REFERENCES

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 Pressuri;ed Water Reactors (PWR's), June 11, 1980.
4. NII 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 COMBUSTION ENGINEERING PRESSURIZED WATER REACTORS (PWR's) l 5

3/4.4 REACTOR COOLANT SYSTEM 3/4.4.1 REACTOR COOLANT LOOPS AND C00LAN1 CIRCULATION i

STARTUP AND POWER OPERATION LIMITING CONDITION FOR OPERATION 3.4.1.1 Both reactor coolant loops and both reactor coolant pumps in each loop shall be in operation.

APPLICABILITY: 1 and 2.*

ACTION:

l With less than the above required reactor coolant pumps in operatica, 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 operatior, and circulatino 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 />, j

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r-REACTOR COOLANT SYSTEM H0T STANDBY LIMITING CONDITION FOR OPERATION 3.4.1.2 a. The reactor coolant loops listed below shall be OPERABLE:

1. Reactor Coolant Loop (A) and at least one associated reactor coolant pump,
2. Reactor Coolant Loop (B) and at least one associated reactor coolant pump,
b. At least one of the above Reactor Coolant Loops shall be in operation.*

APPLICABILITY: MODE 3 ACTION:

a. With less than the above required reactor coolant loops OPERABLE, 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 />,
b. 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 return the required loop to operation.

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.

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 />.

  • All reactor coolant 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 concentration, and (2) core outlet temperature is maintained at least 10 0F below saturation temperature.

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REACTOR COOLANT SYSTEM SHUTDOWN LIMITING CONDITION FOR OPERATION 3.4.1.3 a. At least two of the coolant loops listed below shall be OPERABLE:

1. Reactor Coclant Loop (A) and its associated steam gen-erator and at least one associated reactor coolant pump,
2. Reactor Coolant Loop (B) and its associated steam gen-erator and at least one associated reactor coolant pump,
3. Shutdown Cooling Loop (A)#
4. Shutdown Cooling Loop (B)#
b. At least one of the above coolant loops shall be in operation.*

APPLICABILITY: MODES 4** and 5**

ACTION:

a. With less than the above required loops OPERABLE, immeu!ately initiate corrective action to return the required coolant loops to OPERABLE status as soon as possible; 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 />,
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.
  • 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 concentration, and (2) core outlet temperature is maintained at least 100F below sat. ration temperature.

' ** 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 900 cubic feet or (2) the secondary water temperatur+ of each steam generator is less than 46 0F above each of the RCS cold leg temperatures.

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

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REACTOR COOLANT SYSTEM SURV~ILLAtiCE REQUIREMENT t

4.4.1.3.1 The required residual 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 cetermined to be OPERABLE once per 7 days by verifying correct breaker

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alignments and indicated power availability.

1 4.4.1.3.3 The required steam generator (s) shall be determined OPERABLE by verifying secondary side water 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 OPERATIONS 3/4.9.8 RESIDUAL HEAT REMOVAL AND COOLANT CIRCULATION ALL WATER LEVELS LIMITING CONDITION FOR OPERATION 3.9.8.1 At least one shutdown loop shall be in operation.

APPLICABILITY: MODE 6 ACTION:

a. With less tnan one shutdown cooling loop in operation, except as provided in b. below, suspend all operations involving an increase in the reactor decay heat load or a reduction in boron concentration of the Reactor Coolant System. Close all contain-ment penetrations providing direct access from the containment 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 shutdown cooling 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.

SURVEILLANCE REQUIREMENT 4.9.8.1 At least one shutdown cooling loop shall be verified to be in operation and circulating reactor coolant at a flow rate of greater than or equal to (3000) 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 shutdown cooling loops shall be OPERABLE.* x 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 shutdown cooling loops OPERABLE, immediately initiate corrective action to return 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 requirec shutdown cooling loops shall be determined OPERABLE per Specification 4.0.5.

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  • The normal or emergency power source may be inocerable for each shutdown l cooling loop.

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J 3/4.4 REACTOR COOLANT SYSTEM BASES 3/4.4.1 REACTOR COOLANT LOOPS AND COOLANT CIRCULATION The plant is designed to operate with both reactor coolant loops and associated reactor coolant pumps in operation, and maintain DNBR above 1.30 during all normal operations and anticipated transients.

. 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.

In MODES 4 and 5, a single reactor coolant loop or shutdown cooling 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 shutdown cooling loops to be OPERABLE. ,

The operation of one Reactor Coolant Pump or one shutdown cooling pump J

provides adequate flow to ensure mixing, prevent stratification and produce gradual reactivity changes during boron concentration reductions in the Reactor Coolant System. The reactivity change rate associated with Doron reductions will, therefore, be within the capability of operator recognition and control.

The restrictions on starting a Reactor Coolant Pump during MODES 4 and 5 with one or more RCS cold legs less than or equal to (275)0F are provided to prevent RCS pressure transients, caused by energy additions from the secondary system, which could 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 pressurizer and thereby providing a volume for the primary coolant to expand into, or (2) by restricting starting of the RCPs to when the secondary Water temperature of each steam generator is less than (46)0F above each of the RCS cold leg temperatures.

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i REFUELING OPERATIONS i

BASES l

l 3/4.9.8 COOLANT CIRCULATION

! The reqJirement that at least one shutdown cooling 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 1400 F as required during the REFUELING MODE, and (2) sufficient '

coolant circulation is maintained through the reactor core to minimize the effect of a boron dilution incident and prevent boron stratification, t

i The requirement to have two shutdown cooling loops OPERABLE when there is less than 23 feet of water above the core, ensures that a single failure of the operating shutdown cooling loop will not result in a complete loss of decay heat removal capability. With the reactor vessel head removeo and i 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 shutdown cooling loop, adequate time is provided to initiate emergency procedures to caol the core.

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