ML20199A148

Proposed Tech Specs Pages,Providing Administrative Controls in TS 3/4.9.7,to Permit Spent Fuel Pit Gate Movement Over Irradiated Fuel

ML20199A148
Person / Time
Site:	North Anna
Issue date:	11/05/1997
From:	VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:
Shared Package
ML20199A145	List: ML20199A141 ML20199A148
References
NUDOCS 9711170075
Download: ML20199A148 (10)

Text

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9 I

P ATTACHMENT 2  :

Proposed Technical Specification Change Movement of Spent Fuel Pit Transfer Gate over irradiated Fuel I

North Anna Power Station Units 1 and 2 E! Ed

7 _.

REFUEL ING OPERATIONS  ;

CRANE TRAWL - SPENT FUEL PIT r LIMITING CONDITION FOR OPERATION  !

i 3.9.7 Loads in excess of 2500 pounds shall be prohibited from travel over irradiated fuel  ;

assemblies in the spent fuel pit.This does not apply to movement of any spent fuel pit gate provided each of the following is satisfied:

l

a. the top of the gate (excluding lifting lugs)is no higher than 15 inches above tbc top of the moveable platform crane deck support beam while over irradiated fuel,

b. the gate is rigged to slack free safety cables while over irradiated fuel,

c. irradiated fuel containing Rod Control Cluster Assemblies are excluded along the load path where the gate is moved, and

d. irradiated fuel is prohibited in the cask area when the gate is lifted over the spent fuel cask handling arec. There is no restriction on lift height.

APPLICABil ITY: With irradiated fuel assemblics in the spent fuel pit.  ;

ACTION:

With the requirements of the above specification not satis 0ed, place the crane load in a safe {

condition. The provisions of Specification 3.0.3 are not applicable.

SURVEILLANCE REQUIREMENTS 4.9.7.1 Loads other than the spent fuel pit gates shall be verified to be less than 2500 pounds l prior to movement over irradiated fuel assemblies in the spent fuel pit.

4.9.7.2 For movement of any of the spent fuel pit gates:

a. gate lift height ano slack free redundant rigging shall be verified prior to moving over ,

irradiated fuel,

b. load paths shall be verified net to have irradiated fuel with Rod Control Cluster ,

Assemblies present in the gate load path, and

c. the spent fuel cask handling area shall be verified to have no irradiated fuel present prior to moving a gate over the area.

Amendment No. 8 -

NORTil ANNA - UNIT 1. -3/49-7  :

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

ItEFUELING OPERATIONS BASES 4

3/4.9.6 MANIPL'LATOR CRAN 33 OPERABILITY The OPERA 331LITY requirements for the manipulator cranes ensure that: 1) manipulator cranes will be used for movement of control rods and fuel assemblies; 2) each crane has sufficient load capacity to lift a control rod or fuel assembly, and 3) the core internals and pressure vessel are protected from excessive lifting force in the eveat they are inadvertently engaged during lifting opera'. ions.

3/4.9.2 GtANE TRAVEL - SPENT FUEL PIT The restriction on movements of the spent fuel pit gates over irradiated fuel ensure that redundant rigging will be used in order to prevent a gate drop caused by hoist failure. As shown by calculation,in the event the load is dropped (1) the spent fuel storage racks limit gate penetration and prevent the impact load from being applied to stored fuel,(2) fuel spacing will not be changed and (3) impact loading to the spent fuel pit structure is acceptable.

The restriction on movement of other loads in excess of the nominal weight of a fuel and control rod assembly and associated handling tool over other fuel assemblics 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 distonion of fuel in the storage racks will not result in a critical array. This assumption is consistent with the activity release assumed in the accident analyses.

3/4.9.8 RESIDUAL 11 EAT REMOVAL AND COOLANT CIRCULATION The requirement that at least one residual heat removal (RilR) loop be in operation ensures that (1) sufficient cooling capacity is available to remove decay heat and maintain the water in the reactor pressure vessel below 140'F as required during the REFUELING h1 ODE, and (2) sufficient coolant circulation is maintained through the reactor core to minimize the effect of a boron dilution incident and prevent boron stratification.

After the reactor has shutdown and entered into h10DE 3 for at least 100 hours0.00116 days <br />0.0278 hours <br />1.653439e-4 weeks <br />3.805e-5 months <br />, a minimum RilR system flow rate of 2000 gpm in h10DE 6 is permitted, provided there is sufficient decay heat removal to maintain the RCS temperature less than or equal to 140 F. Since the decay heat power production rate decreases with time after shutdown, the requirements for RHR system decay heat removal also decrease. Adequate decay heat removal is provided as long as the reactor has been shutdown for at least 100 hou rs after entry into h10DE 3 and RilR Dow is suf0cient to maintain the RCS temperature less than or equal to 140*F. The reduced flow rate proviks additional margin to vortning at the RilR pump suction while in hiid Loop Operation. ' >uring a reduction in reactor coolant system boron concentration the Speci0 cation 3.1.1.3.1 requirement to maintain a 3000 gpm Dow rate provides sufficient coolant circulation to minimize the effect of a boron dilution incident and to prevent boron stratifica' ion.

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

NORTil ANNA - UNIT 1 B 3/4 9-2 Amendment No. 32,137

< I REFlfELING OPriRATIONS [

BASES

?

3/4.9.9 CONTAINh1ENT PURGE AND EXilAUST ISOLATION SYSTEh1 The OPERABILITY of this system ensures that the containment vent and purge penetrations will be automatically :solated upon detection of high radiation levels within the containment. The OPERABILITY of this system is required to restrict the release of radioactive material from the containment atmospbere to the erwironment.

3/4.9.10 and 3/4.9.11 WATER LEVEL- REACTOR VESSEL AND SPENT FUEL PIT The restrictions on minimum water level ensure that sufficient water depth is available to remove 99% of the assumed 10% iodine gap activity released from the rupture of an irradiated fuel assembly. The minimum water depth is consistent with the assumptions of the accident analysis.

The minimum water level for movement of fuel assemblies (23 feet above the vessel flange) assures that sufficient water depth is maintained above fuel elements being moved to or from the vessel. With the upper internals in place, fuel assemblics and contro' rods cannot be removed from the vessel. Operations involving the lifting of control rods with the vessel upper internals in place may proceed with less than 23 feet of water above the vessel flange provided that 23 feet of water is maintained above all irradiated fuel assemblies within the reactor vessel.

3/4.9.12 FUEL BUILDING VENTILATION SYSTEhi The limitations on the fuel building ventilation system ensure that all radioactive material released from an irradiated fuel assembly will be filtered through the auxiliary building IIEPA and charcoal filter assemblies prior to discharge to the atmosphere. The Fuel llandling Accident analysis daes not require filtration of the fuel building exhaust in order to meet the analysis criteria.

Ilowever, the OPERABILITY of this system and the resulting iodine removal capacity provide additional conservatism compared with the assumptions of the accident analyses.

NORTil ANNA - UNIT I B 3/4 9 3 Amendment No. 445,4M

i

. i REEL!ELING OPERATIONS i

- CRANE TRAVEL- SPENT FUEL PIT e

\

LIMITING CONDITION FOR OPERATION '

l 3.9.7 I oads in excess of 2500 pounds shall be prohibited from travel over irradiated fuel [

assemblics in the spent fuel pit. This does not apply to movement of any spent fuel pit gate provided each of the following is satisfied:

a, the top of the gate (excluding lifting lugs)is no higher than 15 inches abo _ve the top of  !

the moveable platform crane deck support beam while over irradiated fuel,  !

b. the gate is rigged to slack free safety cables while over irradiated fuel, l

c. irradiated fuel containing Rod Control Cluster Assemblies are excluded along the load .

pstkwhere the gate is moved, and

d. irradiated fuel is prohibited in the cask area when the gate is lifted over the spent fuel cask handling area. There is no restriction on lift height. l APPLICABlIJTY: With irradiated fuel assemblies in the spent fuel pit.

ACTION: l With the requirements of the above specification not satisfied, place the crane load in a safe  :

condition. The provisions of Specification 3.0.3 are not applicable. i SURVEII,1,ANCE REQUIREMENTS 4.9.7.1 Loads other than the spent fuel pit gates shall be verified to be less than 2500 pounds l

• prior to movement over irradiated fuel assemblies in the spent fuel pit.

4.9.7.2 For movement of any of the spent fuel pit gates: ,

n. gate lift height and slack free redundant rigging shall be verified prior to moving over irradiated fuel, r

b. load paths shall be verified not to have irradiated fuel with Rod Control Cluster Assemblies present in the gate load path, and ,

c. - the spent fuel cask handling area shall be verified to have noirradiated fuel present prior i to moving a gate over the area.

i

- NORTil ANN A - UNIT 2 3/49-8 Amendment No.

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REFUELING OPERATIONS HASES 3/4.9.6 MANIPULATOR CRANE OPERABil 1 FY The OPERABILITY requirements for the manipulator cranes ensure that: 1) manipulator crancs will be used for movement of control rods and fuel assemblies; 2) each crane has sufficient load capacity to lift a control iod or fuel assembly, and 3) the core internals and pressure vessel are protected from excessive lifting force in the event they are inadvertently engapd durine, lifting operations.

3/4.9.7 GANE TRAVEL - SPENT FUEL PIT The restriction on movements of the spent fuel pit gates over irradiated fuel ensure that redundant rigging will be used in onder to prevent a gate drop caused by hoist failure. As shown by ca'culation, in the event the load is dropped (1) the spent fuel storage racks limit gate penetration and prevent the impact load from being applied to stored fuel,(2) fuel spacing will not be changed and (3) impact loading to the spent fuel pit structure is acceptable.

The rostriction on movement of other loads in excess of the nominal weight of a fuel and control rod assembly and associated handling teol over other fuel assemblics in the storage pool ensuies 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 distortion of fuel in the storage racks will not result in a critical array. This assumption is consistent with the activity release assumed in the accident analyses.

3/4.98 RilSIDUAL llEAT REMOVAL AND COOLANT CIRCULATION The requirement that at least one cesidual heat removal (R!!R) loop be in operation ensures that (1) sufficient Jooling capacity is available to remove decay heat and maintain the water in the reactor pressure vessel below 140 F as required during the REFUELING MODE, and (2) suf0cient coolant circulation is maintained through the reactor core to minimize the effect of a boron dilution incident and prevent boron stratification.

After the reactor has shutdown and entered into MODE 3 for at least 100 hours0.00116 days <br />0.0278 hours <br />1.653439e-4 weeks <br />3.805e-5 months <br />, a minimum RilR system Dow rate of 2000 ppm in MODE 6 is permitted, provided there is sufficient decay heat removal to re.aintain the RCS temperature less than or equr.1 to 140 F. Since the decay heat power production rate decreases with time after shutdown, the requirements for RilR system decay heat removal also decrease. Adequate decay heat removal is provided as long as the reactor has been shutdown for at least 100 hours0.00116 days <br />0.0278 hours <br />1.653439e-4 weeks <br />3.805e-5 months <br /> after entry into MODE 3 and RilR Dow is sufficient to maintain the RCS temperature less than or equal to 140'F. The reduced How rate provides additional margin to vortexing at the RilR pump suction while in Mid Loop Operation. During a reduction in reactor coolant system boron concentration the Speci0 cation 3.1.1.3.1 requirement to maintain a 3000 ppm flow rate provides sufficient coolant circulation to minimize the effect of a boron dilution incident and to prevent boron stratification.

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

l NOR*lli ANNA - UNIT 2 B 3/4 9 2 Amendment No. Kio

REFUELING OPERATIDMS IIASES N4k9 CONTAINMENT PURGE AND EXilAUST ISOLATION SYSTEM The OPERAlllLITY of this system ensures that the containment vent and purge penetrations will be automatically isolated upon detection of high radiation levels within the containment. The OPERAlllLITY of this system is required to restrict the release of radioactive material from the containment atmosphere to the enviroriment.

3/4.9.10 and 3/4.9.11 WATER LEVEL - REACTOR VESSEL AND SPENT FUEL PIT The restrictions on minimum water level ensure that sufficient water depth is available to remove 99% of the assumed 10% iodine gap activity released from the mpture of an irradiated fuel assembly. The minimum water depth is consistent with the assumptions of'.h accident analysis.

The minimum water level for movement of fuel assemblies (23 feet above the vessel flange) assures that sufficient water depth is maintained above fuel elements being moved to or from the vessel. With the upper internals in place, fuel assemblies and control rods cannot be removed from the vessel. Operations involving the lifting of control rods with the vessel upper internals in place may proceed with less than 23 feet of water above the vessel flange provided that 23 feet of water is maintained above all irradiated fuel assemblies within the reactor vessel.

3/43.12 FUEL HUILDING VENTILATION SYSTEM The limitations an the fuel building ventilation system ensure that all radioactive material released from an irradiated fuel assembly will be filtered through the auxiliary building ilEPA and charcoal Glter assemblies prior to discharge to the atmosphere. The Fuel llandling Accident analysis does not require filtration of the fuel building exhaust in order to meet the analysis criteria.

Ilowever, the OPERAlllLITY of this system and the resulting iodine removal capacity provide additional conservatism compared with the assumptions of the accident analyses.

NORTil ANNA - UNIT 2 Il 3/4 9-3 Amendment No. 94440

ATTACHMENT 3 i

No Significant Hazards Consideration Determination Proposed Technical Specif cation Change Movement of Spent Fuel Pit Transfer Gate over irridlated Fuel North Anna Power Station Units 1 and 2

1 i

SIGNIFICANIII AZARDS CONSIDERATION l

. l The current Technical Specifications requirements prohibit loads in excess of 2500 pounds from traveling over irradiated fuel assemblies in the spent fuel pit. The proposed changes will exempt these requirements for the movement of any of the spent fuel gates provided specific requirements are satisfied.

Due to the number ofirradiated feel assemblies currently stored in the spent fuel pit over years of operation, additional flexibihty is required to accomplish the movement of the spent fuel pit gates and to reduce fuel handling activities in preparation for refueling outages. When a clear path of empty fuel storage cells cannot be established (North Anna 1998 Fall outage) seal maintenance cannot be performed unless relief from the current LCO is granted. The gates are located at exh unit's transfer canal and one near the spent fuel cask separating wall. In order to perform gate seal maintenance prior to each outage, a gate is moved across the irradiated fuel storage area to the cask handling area where it can be lilled out of the pit. When a clear path of empty fuel storage cells cannot be established, seal maintenance cannot be perfonned under the current LCO. Therefore, Virginia Electric and Power Company is proposing changes to the North Anna Power Station Technical Specifications to permit movement of the spent fuel pit gates over irradiated fuel. The proposed changes will establish a new set of administrative controls which permit spent fuel pit gate movement over irradiated fuel while preventing damage to irradiated fuel and maintaining fuel spacing to prevent criticality in the event of a gate handling accident. Adminmrative controls would permit these gates to be carried over irradiated fuel provided the gate lift height is controlled, redundant rigging is installed to prevent a postulated load drop initiated by a hoist failure, and the gate is not carried over irradiated fuel which contains a control rod assembly.

The proposed changes do not involve any physical modifications to the plant or modification in the methods of plant operation which would cause an accident or event of a ditTerent type than previously analyzed. Gate rigging and movement is currently sllowed over empty fuel storage cells and is controlled by NUREG-0612 heavy loads procedures. Commitments to NUREG 0612, as clarified in Attachment 2 of Virginia Electric and Power Company's May 13,1996 letter responding to NRCB 96-02, do not require that a load drop be postulated or analyzed. Changing the Technical Specifications to allow spent fuel pit gate movement over irradiated fuel within the specified administrative controls over gate lift height, use of redundant rigging and RCCAs prohibited from the load path does not create a significant hazards consideration.

Virginia Electric and Power Company has reviewed the proposed changes against the criteria of 10 CFR 50.92 and has concluded that the changes as proposed do not pose a significant hazards consideration. Specifically, opemtion of the North Anna Power Station in accordance with the proposed changes will not:

I

- ^

1. Involve a significant increase in the probability of occurrence or consequences of an

- accident previously evaluated.

The accident in question is a fuel handling accident in the spent fuel pit. The proposed changes will actually reduce the probability of a fuel handling accident by eliminating unnecessary fuel assembly movements. After this change is implemented, only those assemblies containing control rod assemblies will be subject:d to such moves prior to movement of the gates instead of the current practice of moving all the fuel necessary to establish a load paih of empty cells. A redundant riggin[' system will be provided which climinater, fue possibility of a load drop due to a hoist failure. Furthermore, even though the double rigging system makes a loa 6 drop due to a hoist failure an incredible event, a calculation was perfomied to determine the effects of a direct impact load on a single fuel storage cell or the SFp structure. The calculation concludes that there will be no adverse consequences to either irradiated fuel or the SFp structure. The plant design basis fuel handling accident will not be violated . Therefore, with the administrative controls in plaec to eliminate the possibility of a gate drop the probability of occurrence or the consequences of a fuel handling accident are not increased.

2. Create the possibility of a new or different kind of accident from any accident previously evaluated.

The proposed changes establish adequate administrative controls over spent fuel pit gate movements to prevent damage to stored irradiated fuel and fuel racks thereby ensuring the design basis fuel handling accident remains bounding and that fuel spacing is maintained in the racks precluding criticality.

3. Involve a signifi it reduction in any margin of safety.

The new administrative controls ensure that a postulated gate drop will not occur due to compliance with our licensing commitments to NUREG 0612 and the requirement to install a redundant rigging system to eliminate the possibility of a load drop initiated by hoist failure, Analysis has determined that in the event the gate was to be dropped from its controlled lill height: (1) there will be no damage to irradiated fuel caused by the direct impact loading on a single storage cell and (2) the fuel storage rack will maintain fuel in a non-critical array. A new criteria, demonstrating the ability of the pool floor to remain intact after a gate drop has been shown by analysis. New controls prevent the degradation of the existing margin of safety and ensure an adequate margin for the new criteria. The administrative controls added for the gate lift preclude the possibility of a load drop induced by a hoist failure and, therefbre ensure the potential for radioactivity

{, release and inadvertent criticality remain bounded by the present design buis.

Therefore, the margin of safety is not reduced by the proposed change.

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