ML20011D638

Proposed Tech Specs,Revising RHR Sys Flow in Mode 6 (Refueling)

ML20011D638
Person / Time
Site:	Mcguire, McGuire
Issue date:	10/30/1989
From:	DUKE POWER CO.
To:
Shared Package
ML20011D637	List: ML20011D636 ML20011D638
References
NUDOCS 8912280136
Download: ML20011D638 (9)

Text

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U.S. Nuclear Regulatory Ocamission

_' Document Control Desk October 30, 1989 l-1 l

Attachment No.-1 Frg-:+:-3 Cmgn to McGuire hical Specificaticns i

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. 8912280136 DR ADOCK89103005000369 PDC

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. l REFUELING OPERATIONS 3/4.9.8 ' RESIDUAL HEAT REMOVAL ANO COOLANT CIRCULATION HIGH WATER LEVEL i LIMITING CON 0! TION FOR OPERATION j

3.9.8.1 At least one residual heat removal (RNR) loop shall be OPERA 8LE and

• in operation."

i APPLICABMLITY: MODE 6 when the water level above the top of the. reactor

• vessel f'ange is greater than or equal to 23 feet.

ACTION:

With no RHR loop OPERABLE and in operation, suspend all operations involving an increase in the reactor decay heat load or a reduction in boron.concentra-tion of the Reactor Coolant System and immediately initiate corrective action  !

to return the required RHR loop to OPERA 8LE and operating status as soon as possible. Close all containment 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 />.

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' l SURVEILLANCE REQUIREMENTS I

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"The RHR loop may be removed from operation for up to I hour per 8-hour perica during the performance of CORE ALTERATIONS in the vicinity of the reactor i 4

vessel hot legs. f j;.

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i McGUIRE - UNITS.1 and 2 3/4 9-10

, REFUELING OPERATIONS LOW WATER Ltytt l LIMITING CONDITION FOR OPERATION ,

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l L 3.9.8.2 Two independent residual heat removal (RHR) loops shall be OPERA 8LE, and at least one RHR loop shall:be in operation."

l APPLICA8LLITY: M00E 6 when the water level above the top'of.the reactor vessel f'ange is less than 23 feet.- .

ACTION:

l a. With less than the required RHR loops OPERA 8LE, tenediately initiate

corrective action to return the required RHR loops to OPERA 8LE l status, or to establish greater than or. equal to 23 feet of water

! above the reactor vessel flange, as soon as possible..

b. With no RHR 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 RHR loop to operation. Close all- containment 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 />.

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SURVEILLANCE REQUIREMENTS

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" Prior to initial criticality, the RHR loop any be removed from operation for l up to 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> per 8. hour period during the performance of CORE ALTERATIONS in i the vicinity of the reactor vessel hot legs.

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McGUIRE - UNITS 1 and 2 3/4 9-11' o__---_____--___ _ _ _ _ _ _ _ _ _ _ . _ _ . . _ _ . . - _ _ . _ . _ 1._ - _ - . .

__ .__ _ _ _ - _ ~ _ _ _ __ __ _ _ _ _ _ _ _ _ . _ _ _ _ _ _ _ . _ _ _ _ _ _ _

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-REFUELING OPERATIONS

-1 BASES I

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3/4.9.5 COMUNICATIONS The requirement for communications-capability ensures that refueling station personnel can be promptly informed of significant changes in the j facility status or core reactivity conditions during CORE ALTERATIONS.

L l 3/4.9.6 MANIPULATOR CRANE:

The OPERA 81LITY requirements for the manipulator cranes ensure that:

(1) manipulator cranes will be used for-movement of drive rods and fuel i

L assemblies, (2) each. crane has sufficient load capacity to lift a drive rod or-fuel-assembly, and (3) the core internals and reactor vessel are protected from excessive lifting force in the event they are inadvertently engaged i

during lifting operations, i

3/4.9.7 CRANE TRAVEL - SPENT FUEL STORAGE P00L BUILDING i The restriction on movement of loads in excess of th'e nominal weight of a i

fuel and control rod assembly and associated handling tool: over other fuel ..o assemblies in the storage pool ensures that in the event this load.is dropped:

(1) the activity release will be limited to that contained in a single fuel assembly, and (2) any possible distor'. ion of fuel in the storage. racks will not result in a critical stray. This assumotion is consistent with the activity relee.se assumed in the accident analyses.

3/4.9.8 RESIOUAL HEAT REMOVAL AND COOLANT 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 vessel'below 140*F as required during the REFUELING M00E, and (2) sufficient coolant circulation is-maintained through the. core to minimize the offact of a boron dihtion incident and prevent boron stratification.

The requirement to have two'RHR loops OPERA 8LE when there is less tian 23 feet of water above the reactor vessel flange ensures that a single failure of the operating RHR loop will not result in a complate' loss of RHR capability.

With the reactor vessel head removed and 23. feet of water above the reactor vessel flange, 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 I initiate emergency procedures to cool the core.

i l Tr1stc$ Som eb4:ac McGUIRE - UNITS 1 and 2 8 3/4 9-2

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U.S. heler Regulatory 0:mmissicm i

Docuent Control Desk Oetcher 30, 1989 i At' h t 1

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l Insert for BASEE 3/4.9.8:

'!b prevent vortexing in the suction of the RHR puts, the flow rate i requirements fbr the RHR system wre lowered from 3000 gpn to 1000 gpn. A  ;

specific marveillance has been added to ensure the flow remains high enough to ensure the reactor coolant system tanparature rurains less than er equal to 140 degrees-F. 'the groblams associated with vertaxing and inid-loop operations is  !

provided in Generic Intter 88-17, Ioss of Decay Heat. '

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U.S. helaar Regulatory Ccannissica Docannt 0:mtrol Desk l Detaber 30, 1989 Attachnent No. 2 khnical Discussion, No Significant Hazards Analysis and Dmite.-ital Inpact Analysis 1

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U.S. Nuclear Regulatory Ommission Document control Desk October 30, 1989 Attactanent No. 2 hehnical Discussion, No Significant Hazards Analysis and Dntirernantal Dpact. Statement Description of Lyc a Changes he gW anandment w:uldt Osange the requirements for Residual Heat Rumwal to allcw reduced flow during times when the Reactor Coolant System is partially drained. Se change would reduce the specific requirement to maintain Residual Heat Runeval ficw fkom 'at greater than or equal to 3000 gpm" to "at greater than or equal to 1000 gpm' as required by specification surveillances 4.9.8.1 and 4.9.8.2.

Also a surveillance to ensure Reactor coolant System tanperature is maintained belcw 140 degrees-F has been added to the surveillance reg.irements.

We bases for specifications 3/4.9.8.1 and 3/4.9.8.2 have been modified to agree with the pw.3 Technical Specification changes.

Justification /hchnical Discussion Each unit at McGuire Nuclear Station has two independent Residual Heat Removal (ND) Systems. he normal function of the ND System is to remove heat energy frm the core and Reactor coolant (NC) System during cool down and refueling operations. Se ND Systen is also used to transfer refueling water between the Refueling Water Storage Tank and refueling cavity at the beginning and and of refueling operations. he ND System is also used as part of the Safety Injection System and containment Spray System during an accident condition. Detailed information concerning the ND System may be found in Section 5.5.7 of the McGuire FSAR.

As stated in the bases of the McGuire Technical Specifications, the to System and the required flow rates for the ND System serve two purposes. The flow rate ensures aufficient cooling capacity is available to remove decay heat and maintain the water in the reactor vessel below 140 degrees-F as required during refueling. Se flow rate also ensures sufficient coolant circulation is maintained through the core to minimize the offact of a boren dilutice incident and prevent boren stratificaticm.

On Octcher 17, 1988 the NIC issued Generic Istter (GL) 88-17 to licensees. On page 5 of the attachment to the GL, program enhancement no. 5 Technical Specificaticms, recommanded that licensees identify and submit a6propriate changes to escisting Technical Specificaticas that restrict or limit the safety benefit of actions identified in GL 88-17. On pages 5 and 6 of Enclosu.te 1 to the GL in acetion 2.1.2, vortexing is discussed. Vortancing at the junction of the ND System suction line and the NC System will occur if water level is too law, a situaticm to be avoided since this may introduce air into the ND System punp suction.

4 U.S. Nuclear Regulatory 0: emission i h aant Control Desk  !

October 30, 1989  !

Attactunant No. 2 Vortexig can occur more easily when flow is high. As stated in section VII.E.

of NURIG-1269 on page 32, reduced ND System flow rate would provide a greater i

margin against vortenig and preclude an inadvertent loss of decay heat removal capability &2e to air entrairment and cavitation of the ND System punps. Bis  !

amendment will allow Icwor flow rates and reduce our susceptibility to vorte.w.ing.

, me wwc 3 amen &nent will ret change the bases for specifications 3.9.8.1 and 3.9.8.2. Depending on the status of the NC System (i.e. whether the head is on or off, water level in IC system), the tanparature of the system can be monitored using the incore thenemaples, the wide range MIDS or the tenparature indication at the inlet and the discharge of the ND System heat estchangers, men i

1 the NC system is at its Icwest level the taperature irviication at the inlet and the discharge of the ND System heat exchangers is used. In other words, the required flow rate for the ND system will be dictated by the status of the core 1

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(e.g. refuelig oanpleted - Icw decay heat, recently shut down - high decay heat removal) and the level of water in the NC System. Allowing the flow rates to be 1

i reduced will aid in preventing vortexing and air entrainment into the ND and NC '

I Systems. However,1000 gpn is tot always sufficient to maintain NC system tanperature less than or equal to 140 de v G F, for exanple shortly after

shutdown; therefore, a limit of less than or equal to 140 degree-F is established ,

j to ensure sufficient ND system flow is maintained to avoid exceeding this mde 6 requirement. ,

' l As long as a ND ptmp is running, even at flow rates as low as 1000 gpn, there is l enough mixing in the flow to ensure no boren stratification occurs in the NC l i Systen. We ND punps are also needed to minimize the effect of bcron dilution scenario, his is acoonplished by mixing the flow to ensure uniform distribution of the borun in the NC System. Mitigation of a boren dilution scenario is performed by a boren injection f1w path, a centrifugal charging pupp and a borate:1 water source. R ese are required operable by specifications 3.1.2.1, 3.1.2.3 and and 3.1.2.5 during periods of reduced NC System inventory.  ;

mis amendment will also make the surveillance requirements for Technical I Specifications 4.9.8.1 and 4.9.8.2 the same as the surveillance requirements for hchnical Specifications 4.4.1.4.1.2 and 4.4.1.4.2. Wis would aid in l i

eliminating operator confusion fbr the operating requirements of the ND System. j Vortening is not a concern when the water level above the top of the reactor  !

vessel flange is greater than or equal to 23 feet (refarence TS 3/4.9.8.1). -

mis proposed amen &nent to the Technical Specifications has also been reviewed in regard to the analyses being performed to address the ocmoerns raised by Bulletin ,

88-04, Potential Safety-Related Ptmp Ioss. Specifically, operating the Residual '

Heat famoval (ND) ptmps at flw rates less than 3000 gallcms per minute (gpn) will increase the stress on the ND ptmp motor lower bearings. CurrGut evaluations show that the increased stress on the notor bearing is not great enough to cause undue bearing wear for the short term, apprcacimately 10 years.

Therefore, operating the ND platps at the proposed lower flow rate will not inpact the operation of the ND systesn. S e bearings will continue to be monitored as part of the ND ptmp 1:reventative maintenance program for this increase in wear.

If inspection or testing dictate, the bearings would be replaced. ,

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i U.S. Nuclear Regulatory Qasnission humarit Control Desk l Octcher 30, 1989 Attactunant No. 2 No Significant Hasards Analysis 10 TR 50.92 states that a proposed amendment involves no significant hazards considerations if operation in aooordance with the proposed anandment would nots (1) Involve a significant increase in the probability or oansequennes of an accident greviously waluated; or l (2) Create the possibility of a not or different kind of accident from any -

accident grwiously evaluated; or i

l (3) Involve a significant reductica in a margin of safety.

l This change, which would allow the flew requirements for the ND Systen to be ,

i' reduced to prevent vortesting in the ND System, does not involve a significant l increase in the probability or ocmsequenoes of an accident prwiously j waluated. The reduction in flow will not keep the ND System from fulfilling j its safety ftmetions. The ND System will continue to remove enough residual  !

i heat to maintain the NC System below 140 degrees-F, prevent boren dilution, and prevent boron stratification. 'No ND peps (trains) will still be required i operable then there is less than 23 feet of water above the reactor vessel flange. This will ensure that a single failure of the operating residual heat j removal pimp (train) will not result in a ocmplete loss of ND System capability.

4 This change will reduce the probability of an accident since it will reduce the ,

chances of a loss of the ND System due to vortexing or air entrairinent, i

The change to the flow requirements for the ND System will not create the i

possibility of a not or different kind of accident from any accident prwiously i waluated. The ND System will still be operated as before except at lower flow

] rates. The lower flow rates will still allow the ND System to fulfill its '

l' safey functicms. Therefore, no new or different kind of accident fztzn any accident prwiously waluated will be created. .

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! The rW change to the flow requirements for the ND System will not involve a significant reduction in a margin of safety. No functional change is being made to the ND System. The lowering of the flow rate requirements will reduce the chances of rendering the ND System inoperable. This will increase the

margin of safety.

Dwirarsuantal Immet Analysis

The rW Technical Specificatica change has been rwiewed against the

criteria of 10 TR 51.22 for the envirw.elal ocmsideraticms. The proposed change does not involve a significant hazards ocmsideraticm, nor increase the types and amounts of affluents that may be released offsite, nor increase individual or czmulative occupational radiation exposures. Therefore, the propoemd TS change amets the criteria given in 10 CFR 51.22(c)(9) for a categorical exclusion frczn the requirement for an Dwironmental 2npact Statement. <

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