ML20043E653

Forwards Addl Info Re 880930 Application for Amend to License NPF-47 to Implement Generic Ltr 87-09 Requirements Re Preplanned Use of Addl Operating Flexibility

ML20043E653
Person / Time
Site:	River Bend
Issue date:	06/06/1990
From:	Odell W GULF STATES UTILITIES CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
GL-87-09, GL-87-9, RBG-32952, NUDOCS 9006130242
Download: ML20043E653 (8)

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GULF STATES UTELITIES COMP 21NY im n mo n.im .wmna cou si erwwt tousawem AR[ A CODt Ma4 t M (094 Jat B'ibi June 6, 1990 PJG-32952 File No. G9.5, G9.42 U. S. Nuclear Regulatory Ccmnission Document Control Desk Washington, D. C. 20555 Gentlemen:

River Bend Station - Unit 1 Docket No. 50-458 1

Please find attached information regarding Gulf States Utilities '

Campany's (GSU) amendment request dated September 30, 1988 (reference RDG-28910). GSU's letter requested the amendment of i A, 'Ibchnical Facility Operating License NPF-47, Attachment Specifications, to imp 1 ment NIC Generic letter 87-09.

This subnittal contains the justifications for preplanned use of '

the additional operating flexibility allowed by the application of the proposed change to Specification 3.0.4 based on guidance provided in Generic Ictter 87-09 (GL 87-09) . These changes were initially subnitted on Septcrnber 30, 1988 (RIG-28910) and supplemented on June 6, 1990 (IBG-32951) . If the referenced  !

amendment request is approved by the NRC the preplanned use of this flexibility does not require a change to the license and therefore no amendment request is required. GSU request this ,

subnittal be evaluated based on the GL 87-09 subnittals. This  !

request will provide significant improvement in the upccining refueling outage, therefore, GSU requests this change reviewed by August , 1990, i

Please contact Mr. L. A. England at (504) 381-4145 if additional information is required.

Sincerely,  !

W. . Odell I j Manager-Oversight ql River Bend Nuclear Group

/p9 Attachment 9006130242 900606 PDR ADOCK 05000458 h

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'i o cc U. ~ S.; Nuclear. Angulatory Ocamission

611 Ryan Plaza Drive, Suite 1000  ?

4. 4 Arlington, TX --76011 .

Mr. Walt Paulson. i

- U. - S. Nuclear. Regulatory Ccmmission  :

-One h1hite Flint North 1

-11555 Rockville Pike i Rockville, MD 20852 [

' NRC Resident Inspector l Post Office Box 1051-  !

- St. Francisville, IA ~ 70775 .;

.t Mr. William H. Spell,' A&ninistrator

- Nuclear' Energy Divisioni i Iouisiana Departent of Environmental Quality Post Office Box'14690 ,

Baton Rouge, IA 70898 >!;

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'. ryg ggyp Uhis attachment p mvides the justifications for preplanned use of the additional operating flexibility allowed by the application of the proposed change to Technical Specification (TS) 3.0.4 to the action statments of is 3.4.9.2 and 3.9.11.2. During refueling outages at River Bend Station (ISS) various embinations of residual heat reoval (MR) shutdcwn cooling node ,

subsystems, mergency core cooling systems (ECCS), and standby service water subsystems are made inoperable to perform required maintenance, surveillance i testing and inspections. These activities require the plant to enter action 'I stat a nts for these systems at various times during the outage. Preplanned use of the proposed change to TS 3.0.4 will allow the plant to enter i

. Operational Conditions 4 and 5 by allowing reactor vessel head tensioning and detensioning aM a11~ r:::Wr cavity flooding and draining while emplying with these action statenents. With the present technical specification ,

requirments, the above activities would have to be suspended during a change

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in operational conditions in order to make the systma operable as required by the Iro. After conpleting the change in operational conditions, the r systems would again be made inoperable and the action statements entered to cmplete the required maintenance and testing activities.

The current schedule for the third refueling outage relies upon approval of

'the allowance -to utilize the pmposed change to TS 3.0.4 on a preplanned- ,

basis for the action statements of TS 3.4.9.2 and 3.9.11.2. The following. l provides the hsis for the acceptability of pmplanned use of this flexibility.

i Under normal circumstances with the reactor in a shutdown condition, the decay heat proiuced by the irradiated fuel in the reactor vessel is renoved i by the shutdown cooling node the residual heat removal (MR) system. Each shutdown cooling node loop of Mm utilizes a Mm pump and two Mm heat exchangers to remove the decay heat from the reactor vessel and transfers it to -the normal or standby service water systm. As stated in the bases for-TS 3.4.9.1 and 3.4.9.2, a single shutdown cooling mode loop pmvides sufficient heat mnoval capability for removing core decay heat and provides .j adequate coolant mixing to assure accurate tenperature indication. Ilowever, single failure considerations require that two loops be operable or that alternate nothods capable of decay heat rmoval be dmonstrated for each inoperable loop. .

. TS 3.4.9.1 and 3.4.9.2 require two shutdown cooling mode loops of the Mm s system to be operable and, unless at least one recirculation pump is in operation, at least one shutdown cooling mode loop to be in operation.

TS 3.4.9.1 is applicable in Operational Condition 3 (I!Or SmHDCHN) with ,

reactor vessel pressure less than the M m cut-in permissive setpoint and TS 3.4.9.2 is applicable in Operational Condition 4 (OOLD SmHDOWN) .

When in Operational Condition 5 (RFEUELING) with irradiated fuel in the i reactor vessel, TS 3.9.11.1 or 3.9.11.2 applies depending on the water level  ;

in the reactor cavity. TS 3.9.11.2 applies with the reactor cavity water level less than 23 feet above the top of the reactor pressure vessel flange l

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,.- requires two shutdown emling nodo loops of the Ma system be operable with one in operation. No allowance is made here for coolant cimulation with an operating meirculation pmp. TS 3.9.11.1 applies with the reactor cavity water 1cvel greater than or equal to 23 feet above the top of the reactor pressure vessel flange and requires at least one shutdown cooling modo loop of the Mm systm be operable and in operation (again, no provision for coolant circulation with an operating recirculation pump).

'Ihe bases for TS 3.9.11.1 and 3.9.11.2 state that the rcquirment for at least one Mm loop to be operable and in operation or that an alternate nethod capable of decay heat rm oval be demonstrated and an alternate method of coolant mixing be in operation ensures that (1) sufficient cooling capacity is available to renove decay heat and maintain the water in the reactor pressure vessel below 140 degrees F as required during REFUELING, and (2) sufficient coolant circulation would be available through the reactor core to assure accurate temperature indication and to distribute and prevent stratification of the neutron poison in the event it becmes necessary to i i

actuate the standby liquid control system. These bases go on to state that the requironent to have two shutdown cooling mode loops operable when there  !

is less than 23 feet of water alove the reactor pressure vessel flange ensures that a single failure of the operating loop will not result in a cmplete loss of residual heat renoval capability. With the reactor vessel head rmoved and 23 feet of water above the reactor pressure vessel flange, a large heat sink is available for core cooling. Thus, in the event of a failure of the operating Mm loop, adequate time is provided to initiate alternate nothods capable of decay heat rmoval or morgency procedures to cool the core.

Entry into Operational condition 3 with reactor vessel pressure less than the Mm cut-in pennissive is currently allwed by TS 3.4.9.1 7ction c which  !

states that the pmvisions of TS 3.0.4 are not applicable. This action talong with a footnote on TS 3.5.1 which allows one low pressure coolant injection (LPCI) loop to be placed in the shutdown cooling node) allows reactor vessel pressure to be reduced below the Mm cut-in pennissive before placing one RHR shutdown cooling mo3e loop into operation and hence, restoring empliance with the ICO. Because the exception to TS 3.0.4 is placed as Action c and not as part of Action b, entry into this specified condition is also currently permitted with less than the required number of Mm shutdown cooling mode loops operable. The basis for this allowance is i provided bol w.

Action a of TS 3.4.9.1 provides the necessary actions to be taken in the event one or nore Mm shutdown cooling mode loops arc inoperable and Action b provides the necessary actions to be taken in the event no Mm shutdown cooling mode loop or meirculation pump is in operation. While in Action a or b, action must be taken to restom the Ma loop to operable status or operation, as applicable, as soon as possible. Additionally, it is required to provide an alternate method for the function of the Mm shutdown cooling node loop (s) recuired by the ILO (heat rcnoval capability or coolant circulation, as applicable) within one hour. These alternate methods provide a means to cmpletely replace the fumtion(s) of the RHR shutdown cooling nose loop (s) required by the ICO and as such, preserves the ability to cope Page 2 of 6

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.- ith a single failure without loss of ' safety function. Additionally, the change in specified conditions has no effect on decay heat generation or rmoval capability. Further, TS 3;5.1 requires all EOCS to be operable while in Operational Conditions 1, 2 and 3.

As stated in GSU's letter dated Deceber 16, 1988 (Reference RBG-29573),

credit for meeting these action requirments can only be taken if the alternate method (s) chosen has enough decay heat renoval capacity for the

. plant condition at that time. Approved alternate methods available include a Mm shutdown cooling mode loop that cannot be declared operable because of an overdue surveillance test, Mm-LPCI mode, reactor water cleanup system and control rod drive system flow. Any cmbination of these systems may be used to provide the decay heat removal capacity required to qualify as an alternate to the mm shutdown cooling mtxle loop required by the Iro, depending upon the reactor core decay heat being generated at that time.

Additionally,_ as discussed in Updated Safety Analysis Report (USAR) Section 5.4.7.1.5, in the event the capability of the Mm shutdown cooling mode is lost due to either of the two shutdown cooling supply valves failing to operate, an operator would be sent out to operate the valve manually. If this is not feasible and the plant must be shut down as soon as possible, the alternate shutdown method is s ployed. In this procedure, water is drawn frm the suppression pool, pumped threngh the Mm heat exchanger and delivered into the shroud region of the reacer. The vessel water is allowed to overflow the steam lines and discharges bad to the suppression pool via the autmatic depressurization system (ADS) ulve discharge lines. A cmplete loop is thereby established, with sencible and decay heat being transferred to the suppression pool and then to serv.'ce water via the Mm heat exchanger.

Conservative calculations of decay heat renoval requirements have been performed using a emputer code that utilizes the algorithm in Section 3.6 of  ;

ANSI /ANS 5.1-1979. The results of this calculation are contained in Surveillance rest Procedure (STP)-204-0700, " Alternate Decay Heat Removal Verification". This procedure contains a curve which is utilized to conservatively determine the decay heat renoval requirements for the particular plant condition based upon time after shutdown. After deternining the decay heat renoval requirments, the alternate method (s) is selected frm <

a table which provides approved alternate methods and their heat removal capacities. After placing the approved alternate method in service, the operator is required to verify that the alternate method is renoving the reactor decay heat being generated. These actions ensure that the method chosen is capable of empletely replacing the heat removal function of the mm shutdown cooling node loop required by the ICO.

Alternate methods for coolant circulation include operation of: one or both recirculation pumps, or establishing natural core circulation by increasing reactor water level while in Operational Condition 5, or operation of the reactor water cleanup system in conjunction with maximum control rod drive system flow. These methods have been shown to provide adequate coolant circulation in. order to prevent tmperature stratification and permit accurate tmperature nonitoring.

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• • TS 3.5.2 requires at-least two DCCS to be operable in Operational Cbnditions 4 and 5. However, the ECCS are mt required to be operable with the reactor vessel head remved, the reactor cavity flooded, the upper containrent fuel pool gate open and water level maintained greater than or equal to 23 feet above the top of the reactor pressure vessel flange. Application of the operational flexibility allowed bv the proposed change to TS 3.0.4 with the unit shut down will still require at least one IICS to be operable and will not allow any operations with a potential for draining the reactor vessel to be in progress during a change in operational conditions.

The action requirements of TS 3.4.9.2, which are applicable in Operational Condition 4, are the same as those discussed above for TS 3.4.9.1, except for the requirment to restore empliance with the LCO .as soon as possible.

These actions also require establishing an alternate method for the function (s) of the mm shutdown cooling nodo loop (s) required by the 100 L within one ~ hour. Since a period of time has elapsed to achieve Operational L Condition 4, there is less decay _ heat being generated by the core and therefore, there is less urgency needed in restoring the Mm shutdown cooling  !

loop. The alternate method (s) cmpletely replaces the function (s) of the mm shutdown cooling mode loop (s) required by the 100 and therefore, provides for safe continued operation. Additionally, the change in cperational conditions .

by ecoling down has no effect on decay heat generation or rcnoval capability, i TS 3.4.9.2 does not currently contain an exception to the provision of TS 3.0.4. Dased upon the above considerations that less decay heat is being generated in COLD SHUTDOWN, the fact that the specific function (s) of the Mm shutdown cooling node loop (s) required by the Ico is being ccupletely  ;

replaced by the alternate method (s) and that at least one ECCS is operable, a i change in plant conditions to operational Condition 4 should be allowed while emplying with the action requirements of 'IS 3.4.9.2.

The action requirements of TS 3.9.11.2, which are applicable in operational  !

Condition 5 with reactor cavity water level less than 23 feet above the top of the reactor pressure vessel flange, are the same as those discussed above for TS 3.4.9.2, with the exception that an cperating recirculation pmp cannot satisfy the ICO for coolant circulation. As in TS 3.4.9.2, the Actions require establishing an alternate method for the function (s) of the mm shutdown cooling mode loop (s) required by the 100 within one hour.

Because of the time that elapses prior to entering Operational Condition 5, ,

i there ~is less decay heat being generated in the core and.therefore, there is I less urgency needed in restoring the RHR shutdown cooling loop. In this j condition, as above, the alternate method (s) empletely replaces the ,

function (s) of the mm shutdown cooling node loop (s) required by the ICO and L therefore, provides for safe continued operation. Detensioning the reactor pressure vessel head has no effect on decay heat generation or rcnoval capability.

TS 3.9.11.1 requires at least. one RHR shutdown ecoling node loop to be operable and in operation in Operational Condition 5 with reactor cavity water level -greater than or equal to 23 feet above the top of the reactor  !

pressure vessel flange. If no RHR shutdown cooling mode 1 cop is operable or in operation, the actions require (as above) establishing an alternate method j Page 4 of 6 l

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i c io perfom the functions of the RHR shutdown cooling node loop- required by the Ico within one -hour.- As stated in the bases for this technical specification, relaxation frcan the singic failure criterion while in this condition is. permissible because of the reduced decay heat generated by the core and the large heat sink available in the volume of water above the reactor pressure vessel flange. Therefore, in the event of a failure of the operating MIR loop, adequate tine is provided to initiate alternate methods capable of decay heat removal or emergency procedures to cool the core.

Like TS 3.4,9.2 and 3.9.11.2, TS 3.9.11.1 does not currently contain an exception.to the provisions of TS 3.0.4. As a result, this technical J specification prohibits increasing reactor cavity water level above 23 feet l above the top of the reactor pressure vessel flange without an operable MIR 4 shutdown cooling mode loop in operation. Realistically, flooding the reactor cavity provides a " safer" configuration by providing a larger heat sink for core cooling. As in the cases discussed above, reactor core decay heat

[~ generation is further reduced and the alternate method (s) provides a emplete replacment of the functions of the RHR shutdown cooling mode loop required by the ICO. Mditionally, decay heat removal capability is increased when reactor cavity water level is increased. Hence, a change in plant conditions to operational Condition 5 with the reactor. cavity water level greater than or equal to 23 feet above the top of the reactor pressure vessel flange i should be allowed while ccriplying with the action requirements of TS 3.9.11.1.

Following refueling operations, the reactor cavity must be drained to reinstall the reactor vessel head. Hence, the reactor must change applicable conditions from those specified for TS 3.9.11.1 to those specified for l TS 3.9.11.2. In this configuration, two DOCS would have to be operable per TS'3.5.2. Additionally, there would be even less decay heat being generated in the reactor vessel since approximately one third of the irradiated fuel has been replaced with fresh fuel. Since, upon entering the applicability for TS 3.9.11.2 both loops of RHR shutdown cooling are required to be  ;

operabic, an exception to the provisions of TS 3.0.4 could be required even '

if TS 3.9.11.1 10 satisfied. Based on the above considerations that less decay heat is being generated in this condition and the fact that the ,

specific function (s) of the RHR shutdown cooling node loop (s) required by the Ico is being empletely replaced by the alternate method (s), a change in specified conditions to reactor cavity water level less than 23 feet above the top of the reactor pressure vessel flange should be allowed while complying with the action requirements of TS 3.9.11,2. ,

When the reactor head is fully tensioned, the reactor is back in Operational Condition 4, as defined by the technical specifications, and one of the fission product boundaries has been reestablished. Tensioning the reactor pressure vessel head has no effect on decay heat generation or renoval capability. Because of the reduced decay heat being generated and- tJe. fact that the specific functinn(s) of the RHR shutdown cooling node loop (s) required by the Iro is being empletely replaced by the alternate method (s) , .

a change in plant conditions to operational Condition 4 should be allowed  !

while emplying with the action requirements of TS 3.4.9.2.

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e. . g.. #-kn-conclusion,-it_hasbeen shown that for each. of the plant condition

. changes, the singlen failure criteria is maintained as required by each LCO-Land the function (s) that the RHR shutdown cooling mode loop (s) is required to.

e ' perform by. the .'Iro has been ecrpletely replaced by an alternate method (s) .

Additionally, the possible changes in operational conditions have no effect cm decay heat generation or rmoval capability..%erefore, preplanned use of

, the operational flexibility allowed by the proposed change to TS 3.0.4 will L continue to provide an equivalent level of safety during any mode changes into operational ~0ondition 4 or 5 by tensioning or detensioning the . reactor vessel head < or drain the reactor cavity water level to less.than 23 feet

[. above the reactor vessel flange while relying on the Action Statements of TS-F

'3.4.9.2 and 3.9.11.2.

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