ML20006A370

Responds to Variables Identified in SER Re Conformance W/Reg Guide 1.97,Rev 2 for post-accident Instrumentation.Nrc Justification Not Provided to Require Letdown Flow Indication Components to Be Environmentally Qualified

ML20006A370
Person / Time
Site:	Millstone
Issue date:	01/11/1990
From:	Mroczka E NORTHEAST NUCLEAR ENERGY CO., NORTHEAST UTILITIES
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
RTR-REGGD-01.097, RTR-REGGD-1.097 A08378, A8378, TAC-51107, NUDOCS 9001260186
Download: ML20006A370 (14)

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HARTFORD. CONNECTICUT 06141-0270 L L TU %%, %,M,*co*,*', (203) 665 5000 January 11, 1990 4

Jr -Docket No. 50-336 A08378 ,

Re: R.G. 1.97, Rev. E w ,

U.S.' Nuclear Regulatory Commission d ' Attention: Document Control Desk Washington,.DC 20555-  ;

Gentlemen:

Millstone Nuclear Power. Station, Unit No. 2 Conformance to Reoulatory Guide 1.97. Revision 2 (TAC No. 51107)

In a November 22,1989(I) letter, the NRC Staff forwarded to Northeast Nuclear '

Energy Company (NNECO) its Safety Evaluation Report (SER) on conformance to

. Regulatory- Guide 1.97, Revision 2, for Millstone Unit No 2. Also enclosed was the Technical Evaluation Report (TER) from EG&G Idaho, Inc. as an attach-

• ment to the Staff's SER. >

The Staff's :SER identified several variables which were considered- to be

unacceptable for. meeting the recommendations of ~ R.G. 1.97. ' The purpose of this11etter. is to provide' NNEC0's response for these items. Much of the

.information. presented herein as responses to the Staff's concerns has not been .

submitted: previously, : and should be very helpful in reaching resolution for the variables of concern. ,

NNEC0 trusts the foregoing information satisfies ~ Staff concerns regarding Millstone-Unit No. 2's conformance to the provisions of Regulatory' Guide 1.97 ,

forJpost . accident instrumentation. '

' Since a: significant amount of new information is being provided in this. .

t submittal, a conference call or meeting may be appropriate subsequent to Staff L 4- review. NNECO remains available and willing to discuss any concerns that may arise. ,

(1) G. S. Vissing letter to E. J. Mroczka, " Emergency Response Capability--Conformance to Regulatory Guide 1.97, Revision 2, for Millstone Unit No. 2," dated November 22, 1989 with EG&G TER EGG-EA-6857, dated September'1989.

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January 11, 1990 i

Please feelLfree to contact us with any questions.

O Very truly yours, NORTHEAST NUCLEAR ENERGY COMPANY -!

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E. J./Iroczka (/

Seni6r Vice President cc: . W. T.' Russell, Region I Administrator G. S. Vissing, NRC Project Manager, Millstone Unit No. 2.

P. Habighorst, Resident Inspector, Millstone Unit No. 2 g W. J. Raymond, Senior Resident Inspector,' Millstone Unit Nos. 1, 2, and 3  :

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~ Docket No. 50-336 A08378 1

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Attachment'l  !

Millstone Nuclear Power Station, Unit No. 2 Conformance to Regulatory Guide 1,97, Revision 2 1

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January 1990

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Attachment 1- i A08378/Page 1 4

Conformance to Reaulatory Guide 1.97. Revision 2 NNECO offers the following additicnal justifications for. lack of environmental qualification of these specific variables.

Item (a): '

In TER section 3.3.1d EG&G concluded that for the variable accumulator tank level and pressure, the licensee should designate either level or pressure as '

the key variable to directly indicate accumulator discharge and provide instrumentation for that variable that meets the requirements of 10CFR50.49.  ;

The staff, however, is currently generically reviewing the need for environ-mentally qualified Category 2 instrumentation to monitor accumulator tank level and pressure. We will therefore report on the acceptability of this I item when the generic review is complete. l l

Item (b):

In TER section. 3.3.19_ EG&G concluded that for the variable containment sump 7 water temperature, the licensee should provide the recommended instrumentation for the functions outlined in Regulatory Guide 1.97 or identify other instru-mentations (such ' as the residual heat removal- heat exchanger inlet tempera-ture) that satisfy the regulatory guide. The staff, however, is currently -

generically reviewing the need -for environmentally qualified Category 2 instrumentation to monitor containment sump water temperature. We will therefore report on the acceptability of this item when the generic review is complete.

Resoonse: (Items (a) and (b))

As the Staff is currently reviewing- the above two items generically, no response was requested at this time.-

Item (c):

R.G.1.97 recommends Category 2 RHR system flow instrumentation to monitor the operation of the RHR system. The licensee has provided instrumentation which conferms to the Category 2 recommendations of R.G.1.97 except for environ-mental qualification. The licensee has also provided instrumentation that monitors _ the pump motor current. The justification provided by the licensee for not environmentally qualifying the RHR system flow instrumentation is that valve prepositioning and surveillance testing assures system availability prior to an accident.

The staff finds this justification unacceptable, as the flow cannot be deter-mined by pump amperage alone. The licensee should provide RHR system flow l

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Attachment-1 A08378/Page 2- .

instrumentation- that is environmentally qualified in accordance with the provisions of 10CFR50.49 and R.G. 1.97. .

Resoonse:

< The main purpose for monitoring RHR flow during accident conditions is to indirectly infer adequate heat removal. During accident conditions, the most ',

direct indications of adequate heat removal are core temperature and RCS

. temperatures. RHR flow does not directly provide any confirmation of heat '

-removal. In fact, the Safety Function Status Checks (criteria for accomplish-ment of critical safety functions) associated with E0P 2532, Loss of Primary ,

Coolant, do not have any RCS heat removal criteria related to RHR flow.

Incore thermocouple and RCS loop temperatures are monitored by fully qualified instruments.

There are two modes of "RHR" cooling. In normal Shutdown Cooling, the indica- i tion provided by FT-306 is the indication of total flow of the LPSI pumps after- the system has been manually realigned into the RHR mode of operation with the RCS below 300 psia and 300 degrees F. The operation of the system in this RHR mode is a normal mode of operation following a plant shutdown from power operation, but does not involve any harsh environment. Thus, for this mode of operation, environmental qualification is irrelevant.

During accident conditions, FT-306 could only be affected by a harsh radiation environment after initiation of recirculation mode cooling, since it is-located outside containment and would not be exposed to the temperature /

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pressure conditions caused by the LOCA. FT-306 could be used to indirectly infer adequate heat removal when LPSI thru the SDC heat exchangers is used for l- recirculation cooling or 'if Shutdown Cooling were initiated in the long term.

E However, this indication is not a direct indication of heat removal and it is L not .used as a criterion for meeting any critical safety function. As dis-L cussed above, the direct indications (e.g. -

incore temperatures, reactor  ;

vessel level, etc.) are fully qualified. Based on the above, it is concluded '

L that environmental qualification of FT-306 is not required.

Item (d):

L R.G.1.97 recommends Category 2 RHR heat exchanger outlet temperature instru- 1 mentation to monitor the operation of the RHR system. The licensee has

? provided instrumentation which conforms to the Category 2 recommendations of l

R.G.1.97 except for environmental qualification. The justification provided by the licensee for not environmentally qualifying the RHR heat exchanger outlet ~ temperature instrumentation is that the heat exchanger outlet tempera-ture can also be trended by the reactor coolant temperature and surveillance l testing and valve lineup checks assure operation of the RHR system prior to an accident.

The staff finds this justification unacceptable, since sources of coolant other than the RHR could also be cooling the core, and the reactor coolant

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. j g 4 Attachment 1 A08378/Page 3 temperature would- not necessarily be usable in determining the quantity of heat removed by the RHR heat exchanger. The licensee should provide RHR heat  ;

exchanger outlet temperature instrumentation that is environmentally qualified in accordance with the provisions of 10CFR50.49 and R.G. 1.97.  !

Response. -

In this case, as in the case for RHR system flow indication, RHR temperature

.'can only provide an indirect indication of core heat removal.

During the

' post-accident cooling mode of operation, the parameter of concern is the core temperature, which is monitored by a fully qualified system, in-core thermo- l couples. '

1, The indication is only used when the safety injection system has been manually realigned for Shutdown Cooling (RHR) operation with some portion of the total flow directed through the Shutdown Cooling Heat Exchangers. TE-351Y is an RTD l that senses the water temperature on the common line on the outlet side of these heat exchangers to give an indication in the control room of the return temperature of water reentering the RCS during normal shutdown cooling opera-tion where a harsh environment is not a concern.

However, during accident conditions, such as a LOCA, none of the safety injection flow is directed past the sensor TE-351Y, and thus there is no justification- for the sensor and its associated loop being upgraded for environmental qualification purposes for the LOCA condition.

Item (e):

R.G. 1.97 recommends Category 2 high pressure injection system flow instrumen-tation to monitor.the operation of the safety injection system. The licensee ,

has provided instrumentation which conforms to.the Category 2 recommendations of R.G. 1.97 except for environmental qualification. The . licensee has also provided instrumentation that monitors the pump motor current. The justifica .

tion provided by the licensee is that valve prepositioning and surveillance testing assures system availability prior to an accident.

The -staff finds this justification unacceptable, as the flow cannot be deter-mined by pump amperage alone. The licensee should provide high pressure injection system flow instrumentation that is environmentally qualified in accordance-with the provision of 10CFR50.49 and R.G. 1.97.

Item (f):

R.G.1.97 recommends Category 2 low pressure injection system flow instrumen-tation to monitor the operation of the safety injection system. The licensee

-has provided instrumentation which conforms to the Category 2 recommendations of R.G.1.97 except for environmental qualification. The licensee has also l

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. Attachment-l A08378/Page 4.

provided instrumentation that monitors the pump motor current. The justifica-tion provided by the licensee is- that valve prepositioning and surveillance testing assures system availability prior to an accident.

The staff finds this justification unacceptable, as the flow cannot be deter-mined by pump amperage alone. The licensee should provide low pressure injection system flow instrumentation that is environmentally qualified in accordance with'the provisions of 10CFR50.49 and R.G. 1.97.

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Response: [ Items (e) and-(f)]

HPSI. LPSI Flow Indication HPSI and LPSI flow rates are each measured by separate flow transmitters in each of the four cold leg injection lines. (HPSI - F311, 321, 331, 341 LPSI -

F312, 322, 332, 342). The sensors for these instruments are located in a normally mild environment (outside containment). The only time these sensors would experience a harsh environment is during a steam line break outside  !

containment or during the-recirculation phase following a LOCA. j During a LOCA, the HPSI and LPSI flow indications are used to determine j acceptability of total safety injection flows. Since a failure of these i transmitters will not have any direct affect on operation of HPSI or LPSI, the  !

only' potential consequence of failure would be to cause an incorrect operator i o action. In the Millstone. Unit No. 2 Emergency Operating Procedures, if the i total' safety injection flow rate is-not acceptable, the operator is instructed l to ensure availability of electric power to system components, ensure correct l system valve lineup, and start any idle injection pumps. If the HPSI and LPSI I flow indications were to erroneously indicate an unacceptable total flowrate, these actions would not in any way aggravate mitigation of the accident. If i' the HPSI and LPSI indications were to erroneously indicate an acceptable flow

. rate (when in fact the actual flow was unacceptable), there would still be no adverse consequences. The adequacy of core cooling is not measured by safety

-injection flow rate. In the Millstone Unit No. 2 E0Ps (as in the generic CE0G Emergency Procedure Guidelines) adequate core cooling .is measured by core exit thermocouple temperatures, RCS subcooling, reactor vessel level, and' heat removal via steam generators. These criteria are of higher priority than other criteria which are based on HPSI and/or LPSI flow rate. Only when these ,

criteria are not met is the operator directed to implement other functional recovery actions. Since these parameters are measured by qualified instru-ments, the ability of the operator to mitigate inadequate core cooling is not affected.

These flow sensors could be affected by a harsh environment resulting from a steam line break outside containment. As in the discussion for LOCAs above, i safety injection flow alone is not used for making critical decisions in the E0Ps. Further, HPSI and LPSI flow in a steam line break are less important >

-than in a LOCA since core uncovery will not result from a steam line break.

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Attachment 1 A08378/Page 5 t

Therefore, the lack of qualified HPSI and LPSI flow indication is not signifi- .

cant.

• Item (a):

R.G. 1.97 recommends Category 2 containment spray flow instrumentation to monitor the operation of the containment cooling system. .The licensee has provided instrumentation which conforms to the Category 2 recommendations of R.G. 1.97 except for environmental qualification. The licensee has also provided instrumentation that monitors the pump motor current. The justifica-tion provided by: the licensee is that valve prepositioning and surveillance testing assures system 1vailability prior to an accident. -

The staff finds this justification unacceptable, as the flow cannot be deter-mined by -' pump amperage alone. The licensee should provide containment spray flow instrumentation that is environmentally qualified in accordance with the

• provisions of 10CFR50.49 and R.G.1.97.

Response

Containment spray flow is measured by one flow transmitter in each containment spray line, outside containment, downstream of the shutdown cooling heat exchanger. Containment spray may be required to function during a LOCA or main - steam line break inside containment. Since the sensors are located outside containment, they would be subjected to a harsh environment only in the ' event of a steam line break outside containment or during post-LOCA recirculation mode cooling.

In a LOCA, containment spray is initiated when containment pressure increases to 27 psig, and spray is terminated when containment pressure is less than 10 psig. In the. injection phase (when the flow transmitters are not affected by the environment) containment spray flow is important in that the design basis assumes 1350 gpm of spray in order to limit peak containment pressure.

However, during -recirculation mode cooling, which is not initiated until at least 40 minutes after the break, the actual containment spray flow rate is

'far less important since containment pressure is significantly lower (peak occurs at about 240 seconds). During recirculation, heat is also removed from containment via containment- spray through the shutdown -cooling heat exchang-ers, however at this time the heat load is also significantly lower and the Containment Air Recirculation coolers also provide this function. Thus, during the only time that these flow sensors could be affected by a harsh envirc, ament, the flow rate is not critical. It is important to note that the function of containment spray is to limit post-accident containment pressure-

- and provide heat removal from the containment. The most important parameter is containment pressure and this is measured by a fully qualified . instrument.

In the Millstone Unit No. 2 Emergency Operating Procedures, following transfer to sump recirculation, there are no criteria which require a specific contain-

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ment spray flow rate. Even if spray were still required (i.e. - containment

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Attachment 1 A08378/Page 6  ;

pressure remains above 10 psig) and the flow sensors were to give an erroneous indication, the operator would not take any incorrect actions. Based on this, it is concluded that environmental qualification of these instruments is not warranted.

Item (h): ,

R.G. 1.97 recommends Category 2 CVCS letdown flow-out instrumentation to monitor the operation of the CVCS. The licensee has provided instrumentation i to monitor this variable, but has not provided any details about this instru-l mentation. The licensee states pressurizer level or differential pressure across the letdown filter can be used to backup the CVCS letdown flow-out instrumentation.

The staff- finds this justification unacceptable, as the licensee has not- I adequately described the instrumentation to monitor this variable. The i licensee should provide CVCS letdown flow-out instrumentation that meets all I the Category 2 criteria of R.G. 1.97.

Response

Letdown flow indication, F-202 (0 to 140 GPM), is used during normal operation to monitor letdown from the RCS through the CVCS. Coolant is letdown or drained from the RCS during normal operation for control, monitoring, and purification purposes. The letdcwn flow approximately matches makeup (Charg-ing) flow, with the difference being due to reactor coolant pump seal bleedoff flow.

During accident conditions such as a LOCA, the letdown line is immediately isolated as an automatic function of the Safety Injection Actuation Signal (SIAS) and the Containment Isolation Actuation Signal (CIAS), to help ensure potential areas of coolant loss are isolated. Thus after isolation, there is-no letdown flow and the flow indicator is of no use. Review of the LOCA procedure E0P 2532 shows there is no reference to letdown flow indication and letdown is never reestablished following the LOCA event. Letdown is not required to successfully mitigate any design basis accident. Therefore, there is:no justification to require the letdown flow indication components to be environmentally qualified.

Item (i):

R.G.1.97 recommends Category 2 CCW temperature to ESF system instrumentation L

to monitor the operation of the cooling water system. The licensee has provided instrumentation which conforms to the Category 2 recommendations of R.G.1.97 except for environmental qualification. The justification provided by the licensee is that surveillance testing assures system availability prior

,, to an accident.

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Attachment 1 A08378/Page . 7-

'The staff finds this justification inadequate and unacceptable. The licensee should provide CCW temperature to ESF system instrumentation that is environ- ,

mentally. qualified in accordance with the provisions of 10CFR50.49 and R.G.

1. 97. .

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Response

RBCCW temperature is measured by three temperature sensors, one in each header downstream 'of the RBCCW heat exchangers. These sensors are located in the auxiliary building and would not be exposed to a harsh pressure / temperature environment following a LOCA, but could conceivably be exposed to high radia-tion during recirculation mode post-LOCA cooling. However, failure of _ thesel

-sensors will have no effect on system operation and the Emergency Operating Procedures do not specify any actions to be taken based on these temperature sensors. It should be noted that the RBCCW system is always running (to ,

support normal operation) and the temperature sensors are fully qualified for the environment they will be exposed to (mild environment) up to the time of  ;

Sump Recirculation Actuation (SRAs).  !

Thus, although not' needed for mitigation of any accident, qualified tempera-ture indication would be available to confirm proper initial RBCCW operation. J A steam line break outside containment could result in a harsh environment for these temperature sensors. However, RBCCW is less important for this accident

_ (since containment heat removal is not critical) and, as stated above, RBCCW

-temperature is not an important parameter in any accident since it is not the a basis for any operator actions.  ;

4 Item Li):

R.G. 1.97- recommends Category 2 CCW flow to ESF system instrumentation to "

monitor the operations of the cooling water system. The licensee has provided

instrumentation which conforms to the Category 2 recommendations of R.G.1.97 y except for environmental qualification. The licensee has also provided D

instrumentation - that monitors the pump motor current. The justification i provided by-the licensee is that valve prepositioning and surveillance testing i assures system availability prior to an accident.

The staff finds this justification unacceptable, as the flow cannot be deter- j mined by pump amperage alone. The licensee should provide CCW flow to ESF l l system instrumentation that is environmentally qualified in accordance with '!

the provision of 10CFR50.49 and R.G. 1.97.  ;

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-Response:

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L RBCCW flow is measured by two flow sensors, one in each header downstream of the RBCCW heat exchangers. These sensors are located in the auxiliary build-ing and would not be exposed to a harsh pressure / temperature environment _

following a LOCA, but could conceivably be exposed to high radiation during '

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Attachment l' i A08378/Page 8 j recirculation mode post-LOCA cooling. However, failure of these sensors will

.have no effect on system operation and the- Emergency Operating Procedures do 1 not specify any actions to be taken based on these flow sensors. It should be ,

noted that- the. RBCCW system is always running (to support normal operation) and the flow sensors are fully qual.ified for the environment they will be exposed to (mild environment) up to the time of Sump Recirculation Actuation (ras). Thus, although not needed for mitigation of any accident, qualified flow indication would be available to confirm proper initial RBCCW operation.

, 'A steam line break outside containment could result in a harsh environment for  !

these flow sensors. However, RBCCW is less important for this accident (since containment heat removal is not critical) and, as stated above, RBCCW flow rate is not an important parameter in any accident since it is not the basis ,

for 'any operator actions. Therefore, we believe environmental qualification ,

is not warranted. .

Item (k):

R.G. 1.97 recommends Category 1 wide range steam generator level instru-mentation, with a range from the tube sheet to the separators to monitor the operation of the steam generators. The instrumentation provided by the-licensee has a range from the top of the tube bundles to ' the separators.

' Thus, the length o# the tube bundles is- not measured. The justification provided by the licensee is that the auxiliary feedwater system is automati-cally initiated on a low level signal and is of sufficient capacity to restore ,

the level to normal conditions even with a single failure. The main feedwater -

pumps can be manually ramped back to 5 percent flow to accomplish this 'also, Primary -side temperature and pressure and- main and auxiliary feedwater flow rates are available to verify the secondary side availability as a heat sink. '

The licensee also states that there is sufficient inventory to maintain an L . adequate heat sink with no feedwater flow for 22 minutes'.

The licensee is anticipating a decision on replacing the steam generators by

.the end :of the 1991 refueling outage. Should the steam generators be l, replaced, the licensee will include wide range level indication. Should the I

licensee decide not to replace the steam generators, there is no commitment to provide the wide range level indication.

l Based on the alternate instrumentation, the staff finds that continued opera-tion, until wide range steam generator level instrumentation is installed, is acceptable. . However, deferring a decision committing to install this instru-mentation until 1991 is ur. acceptable. The licensee should commit to and L install Category 1 wide range steam generator level instrumentation regardless I of steam generator replacement.

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Epsponse:

Steam Generator Wide Ranae level Indication  :

The present narrow range of steam generator level from the top of the tubes to the moisture separators provides adequate information to the control room  ;

operators for both normal and accident conditions. ]

During accident and transient conditions the present narrow range of indica-tion provides signals from fully qualified (EEQ and Seismic) transmitters that i provide reactor trip functions on decreasing level at 36 percent of the  !

indicated range. These same transmitters continue to function and monitor decreasing level conditions if the transient continues, and at 12 percent of

- the indicated range, the Auxiliary feedwater system is automatically initiat- ,

ed. This automatic initiation starts two fully qualified (EEQ and seismic) electrically powered pumps, each capable of providing core cooling and steam generator level restoration. The indication of auxiliary feedwater flow rate to each steam generator is provided by fully cualified and redundant flow ,

indication systems. The specific auxiliary feecwater flow rate required in I the E0Ps ensures that the steam generators will remain effective for heat i removal during all design basis events, regardless of indicated steam gener- j ator water level. The flow control valves in the AFW system also automatical-ly open and are also fully qualified. In summary, the method of restoring steam generator level is a redundant and fully qualified system and will be available as needed to support the steam generators as the primary means of core heat removal with or without wide range level indication.

In addition, the effectiveness of the steam generators in heat removal is determined more directly by observing RCS loop temperatures or core tempera-tures, both of which are provided by fully qualified systems, and do not rely L on any steam generator level indications. Steam generator level alone is not l as good an indicator of heat removal as RCS loop temperatures.  ;

y In addition, after a loss of steam generator level indication during a tran-e sient, and AFW has been initiated, no other action is taken based on steam l generator level, until it returns to "high" in the narrow range (aparoximately 75%), where the flow rate is reduced to prevent overfilling anc/or excess i

cooling of the RCS. Again, since the primary concern during any severe transient is core cooling, and steam generator level indication has little

• l direct effect on this parameter, the present narrow-range is sufficient.

Steam generator wide-range level instrumentation would be of greatest benefit in evaluating total loss-of-feedwater events and in determining when to implement once through cooling (primary feed and-bleed). However, total loss-of-feedwater events are beyond design basis accidents for Millstone Unit l No.- 2 and therefore need not be considered in our response to Regulatory Guide 1.97.-

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[L Attachment 1 I A08378/Page 10 l NNECO does not intend to commit to the installation of wide range level (WRL) l instrumentation in the existing steam generators at Millstone Unit No. 2 at  !

this time. There is no operator action that would be taken in a design basis  !

E accident scenario that is dependent on Wide-Range Level instrumentation, j Installation would involve an expenditure of approximately $2.5 million and an j estimated 15 man rem. These figures are significant enough to preclude an l r1 immediate decision to install the WRL instruments. NNECO intends to conduct the Individual Plant Examination which will evaluate event 3 basis (e.g., total loss of-feedwater events), as scheduled (sand )beyond use thethe datadesign L

. gained from it to contribute to the decision making process regarding modifi-l cations to the existing steam generators, if a decision to replace them has not already been made. We believe it is not prudent to make a decision without the IPE results.

The above information clarifies NNECO's rationale for postponing the decision to install wide range level instruments for the existing steam generators.

NNECO acknowledges the Staff's position on this subject. NNECO would like to  ;

better understand the regulatory basis for the Staff's position so as to meaningfully evaluate its options, especially given the undetermined safety significance to design basis accident mitigation and the costs associated with implementation of the Staff position. It is estimated, based on engineering  !

judgment, that the benefit to public safety would be negligible. Currently, it is our view that the expenditure of some $2.5 million and 15 man rem for this purpose is not the optimum use of these resources for improving public health and safety.

Further discussion of this subject should include the Staff's technical basis for requiring wide range level instrumentation on the existing Millstone Unit No. 2 steam generators.

item (1):  ;

R.G.1.97 recommends that the containment fan heat removal system be monitored r for operation by plant specific Category 2 instrumentation. The licensee has provided instrumentation which conforms to the Category 2 recommendations of R.G.1.97' except for environmental qualification. The licensee monitors the containment air recirculation and cooling system (CARCS) by monitoring the  !

l temperature of the inlet and outlet of the cooling water (reactor building closed cooling water system) heat exchangers. The licensee also monitors the flow from the fan blowers. The justification provided by the licensee is that -

! redundancy in design, surveillance testing, valve position verification, and i Category 1 containment pressure instrumentation are adequate to assure system l operation.

(1) E. J. Mroczka letter to U.S. Nuclear Regulatory Commission, " Response to Generic Letter 88 20," dated July 27, 1989, 1

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A08378/Page 11 )

The staff finds this justification unacceptable, as the containment pressure instrumentation cannot distinguish between the containment spray system l operation and CARCS operation. The system testing and verification will assure a state of system readiness, but cannot show proper system operation under accident conditions. The existing instrumentation is acceptable except ,

for the lack of environmental qualification. The licensee should provide

i int trumentation, for the purpose. of monitoring containment cooling, that is environmentally qualified in accordance with the provisions of 10CFR50.49 and R.G. 1.97. l fltipJ2Dit:

Performance of the Containment Air Recirculation System can be monitored by I several parameters, including fan cooler inlet and outlet temperatures and 1 cooler outlet flow rate. All of these sensors are located outside of contain- '

i ment and are therefore r.ot affected by the LOCA environment until recircula- .

tion mode cooling begins, at which point the sensors could be subjected to  ;

I only a high radiation environment. As discussed in response to the Staff's i position en containment spray instrumentation, containment heat removal is i most critical early on in an accident since during recirculation cooling there are redundant means of containment heat removal (SDC heat exchangers and CAR coolers). During the injection phase of a LOCA, when containment heat removal is critical, the instruments monitoring CAR system performance are fully qualified for the environment they will be exposed to. These instruments, although not called for in the E0Ps, will therefore be available if desired to L confirm proper initial system operation. Note that after the injection phase ends and recirculation begins, there are no operator actions that would directly affect CAR system operation.

The above discussion notwithstanding, it is important to note that the most important parameters related to operation of the CAR system are not the i variables discussed above but rather containment pressure. In its SER, the Staff states that NNECO's earlier justification was unacceptable "as the containment pressure instrumentation cannot distinguish between the contain- ,

ment spray system operation and CARCS operation." This is true, however we i note that it makes no difference if the critical safety function is satisfied due to spray or CAR system operation. This is reflected in the Emergency Operating Procedures philosophy, which call for monitoring of containment pressure rather than specific system operating parameters. Note that containment pressure indication is provided by a fully qualified instrument.

Based on the above discussion and the fact that failure of these indications will not result in any incorrect operator actions, it is concluded that environmental qualification of these instruments is not required.

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