ML051220095

Technical Specifications, Eliminates Secondary Containment Operability Requirements When Handling Sufficiently Decayed Irradiated Fuel or Performing Core Alterations

ML051220095
Person / Time
Site:	Pilgrim
Issue date:	04/28/2005
From:	Boska J NRC/NRR/DLPM/LPD1
To:	Kansler M Entergy Operations
References
TAC MC2705
Download: ML051220095 (12)

Text

PNPS TABLE 3.2.D RADIATION MONITORING SYSTEMS THAT INITIATE AND/OR ISOLATE Minimum # of Operable Instrument Channels Per Trip Svstem (1) Trip Function Trip Level Setting Action (2) 2 Refuel Area Exhaust Monitors Upscale, <100 mr/hr AorB 2 Refuel Area Exhaust Monitors Downscale AorB NOTES FOR TABLE 3.2.D

1. Whenever the systems are required to be operable, there shall be two operable or tripped trip systems. If this cannot be met, the indicated action shall be taken.

2. Action A. Cease movement of recently irradiated fuel assemblies and operations with potential to drain the reactor vessel (OPDRVs).

B. Isolate secondary containment and start the standby gas treatment system during movement of recently irradiated fuel assemblies and operations with potential to drain the reactor vessel (OPDRVs).

Amendment No. 89, 17-, 215 314.2-24

LIMITING CONDITIONS FOR OPERATION SURVEILLANCE REQUIREMENTS 3.7 CONTAINMENT SYSTEMS (Cont.) 4.7 CONTAINMENT SYSTEMS (Cont.)

B. Standby Gas Treatment System and B. Standby Gas Treatment System and Control Room High Efficiency Air Control Room High Efficiency Air Filtration Filtration System System

1. Standby Gas Treatment System 1. Standby Gas Treatment System

a. Except as specified in 3.7.B.1.c or a. 1. At least once per operating cycle, 3.7.B.1.e below, both trains of the it shall be demonstrated that standby gas treatment shall be pressure drop across the operable when in the Run, Startup, combined high efficiency filters and and Hot Shutdown MODES, during charcoal adsorber banks is less movement of recently irradiated fuel than 8 inches of water at 4000 cfm.

assemblies in the secondary 2. At least once per operating cycle, containment, and during operations demonstrate that the inlet heaters with a potential for draining the on each train are operable and are reactor vessel (OPDRVs), capable of an output of at least 20 kW.

or 3. The tests and analysis of Specification 3.7.B.1.b. shall be the reactor shall be in cold performed at least once per shutdown within the next 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />. operating cycle or following painting, fire or chemical release in any ventilation zone communicating with the system while the system is operating that could contaminate the HEPA filters or charcoal adsorbers.

4. At least once per operating cycle, automatic initiation of

b. 1. The results of the in-place cold DOP tests on HEPA filters shall show >99% DOP removal. The results of halogenated hydrocarbon tests on charcoal adsorber banks shall show

>99.9% halogenated hydrocarbon removal.

Amendment No. 42, 0, , 52, 42,11,151, 161, 170, 187, 01, 206,215 3/4.7-1 1 I

LIMITING CONDITIONS FOR OPERATIONR SURVEILLANCE REQUIREMENTS 3.7 CONTAINMENT SYSTEMS (Cont.) 4.7 CONTAINMENT SYSTEMS (Cont.)

B. Standby Gas Treatment System and B. Standby Gas Treatment System and Control Room High Efficiency Air Control Room High Efficiency Air Filtration System (Cont.) Filtration System (Cont.)

b. 2. The results of the laboratory each branch of the standby gas carbon sample analysis shall treatment system shall be show each carbon adsorber bank demonstrated, with Specification is capable of >97.5% methyl 3.7.B.1.d satisfied.

iodide removal at 70% R.H. and

5. Each train of the standby gas 86 0 F. The carbon sample shall treatment system shall be operated be obtained in accordance with for at least 15 minutes per month.

Regulatory Position C.6.b of Regulatory Guide 1.52, Revision 6. The tests and analysis of 2, March 1978 and tested in Specification 3.7.B.1.b.2 shall be accordance with ASTM D3803- performed after every 720 hours0.00833 days <br />0.2 hours <br />0.00119 weeks <br />2.7396e-4 months <br /> of 1989. The analysis results are system operation.

to be verified as acceptable b. 1. In-place cold DOP testing shall be within 31 days after sample performed on the HEPA filters after removal, or declare that train each completed or partial inoperable and take the actions replacement of the HEPA filter bank specified in 3.7.B.1.c.

and after any structural maintenance

c. From and after the date that one on the HEPA filter system housing train of the Standby Gas Treatment which could affect the HEPA filter System is made or found to be bank bypass leakage.

inoperable for any reason, 2. Halogenated hydrocarbon testing continued reactor operation is shall be performed on the charcoal permissible only during the adsorber bank after each partial or succeeding seven days providing complete replacement of the charcoal that within 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> all active adsorber bank or after any structural components of the other standby maintenance on the charcoal gas treatment train are verified to adsorber housing which could affect be operable and the diesel the charcoal adsorber bank bypass generator associated with the leakage.

operable train is operable.

If the system is not made fully operable within 7 days, reactor shutdown shall be initiated and the reactor shall be in cold shutdown within the next 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />.

Amendment No. 12, 50, 52, 112, 111, 151, 161,170, 187, 215 3/4.7-12 I

LIMITING CONDITIONS FOR OPERATION SURVEILLANCE REQUIREMENTS 3.7 CONTAINMENT SYSTEMS (CONT) 4.7 CONTAINMENT SYSTEMS (Cont)

B. Standby Gas Treatment System and B. Standby Gas Treatment System and Control Room High Efficiency Air Control Room High EfficiencV Air Filtration System (Cont) Filtration System (Cont)

d. Fans shall operate within +/- 10% of 4000 cfm.

e. From and after the date that one train of the Standby Gas Treatment System is made or found to be inoperable for any reason, movement of recently irradiated fuel assemblies and operations with a potential for draining the reactor vessel (OPDRVs) are permissible only during the succeeding 7 days providing that within 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> all active components of the other train are verified to be operable and the diesel generator associated with the operable train is operable.

If the system is not made fully operable within 7 days, i) place the operable train in operation immediately OR ii) suspend movement of recently irradiated fuel assemblies in secondary containment and initiate actions to suspend OPDRVs. Any fuel assembly movement in progress may be completed.

I AmendmentNo.42.-50. 51. 5. 101. 112. 1. 15 16. 3/4171 3/4.7-1 3

LIMITING CONDITIONS FOR OPERATION SURVEILLANCE REQUIREMENTS 3.7 CONTAINMENT SYSTEMS (Cont.) 4.7 CONTAINMENT SYSTEMS (Cont.)

B. Standby Gas Treatment System and B. Standby Gas Treatment System and Control Room High Efficiency Air Control Room High Efficiency Air Filtration System (Cont.) Filtration System (Cont.)

2. Control Room High Efficiency Air 2. Control Room High Efficiency Air Filtration System Filtration System

a. Except as specified in Specification a. At least once per operating cycle the 3.7.B.2.c or 3.7.B.2.e below, both pressure drop across each combined trains of the Control Room High filter train shall be demonstrated to be Efficiency Air Filtration System used less than 6 inches of water at 1000 for the processing of inlet air to the cfm or the calculated equivalent.

control room under accident conditions shall be operable when in the Run, Startup, and Hot Shutdown MODES, during movement of recently irradiated fuel assemblies in the b. 1. The tests and analysis of secondary containment, and during Specifications 3.7.B.2.b shall be operations with a potential for draining performed once per operating cycle the reactor vessel (OPDRVs), or following painting, fire or or chemical release in any ventilation the reactor shall be in cold shutdown zone communicating with the within the next 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />. system while the system is operating.

b. 1. The results of the in-place cold DOP tests on HEPA filters shall 2. In-place cold DOP testing shall be performed after each complete or show 299% DOP removal. The results of the halogenated partial replacement of the HEPA filter bank or after any structural hydrocarbon tests on charcoal maintenance on the system adsorber banks shall show Ž99.9% housing which could affect the halogenated hydrocarbon removal HEPA filter bank bypass leakage.

when test results are extrapolated to the initiation of the test. 3. Halogenated hydrocarbon testing shall be performed after each

2. The results of the laboratory complete or partial replacement of carbon sample analysis shall show the charcoal adsorber bank or after 297.5% methyl iodide removal at any structural maintenance on the 70% R.H. and 86 0F. The carbon system housing which could affect sample shall be obtained in the charcoal adsorber bank bypass accordance with Regulatory leakage.

Position C.6.b of Regulatory Guide 1.52, Revision 2, March 1978 and 4. Each train shall be operated with tested in accordance with ASTM the heaters in automatic for at least D3803-1989. The analysis results 15 minutes every month.

are to be verified as acceptable within 31 days after sample removal, or declare that train inoperable and take the actions specified in 3.7.B.2.c.

Amendment No. 12, 50, 52,112,111, 15, 161, 170,187, 215 3/4.7-14

LIMITING CONDITIONS FOR OPERATION SURVEILLANCE REQUIREMENTS 3.7 CONTAINMENT SYSTEMS (CONT) 4.7 CONTAINMENT SYSTEMS (Cont)

B. Standby Gas Treatment System and B. Standby Gas Treatment System and Control Room High Efficiency Air Control Room Hich Efficiency Air Filtration System (Cont) Filtration System (Cont)

c. From and after the date that one 5. The test and analysis of train of the Control Room High Specification 3.7.B.2.b.2 shall be Efficiency Air Filtration System is performed after every 720 hours0.00833 days <br />0.2 hours <br />0.00119 weeks <br />2.7396e-4 months <br /> of made or found to be inoperable for system operation.

any reason, reactor operation is permissible only during the succeeding 7 days providing that c. At least once per operating cycle within 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> all active demonstrate that the inlet heaters on components of the other CRHEAF each train are operable and capable train are verified to be operable and of an output of at least 14 kw.

the diesel generator associated with the operable train Is operable.

If the system is not made fully d. Perform an instrument functional test operable within 7 days, reactor on the humidistats controlling the shutdown shall be initiated and the heaters once per operating cycle reactor shall be in cold shutdown within the next 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />.

d. Fans shall operate within + 10% of 1000 cfm.

e. From and after the date that one train of the Control Room High Efficiency Air Filtration System is made or found to be inoperable for any reason, movement of recently irradiated fuel assemblies and operations with a potential for draining the reactor vessel (OPDRVs) are permissible only during the succeeding 7 days providing that within 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> all active components of the other train are verified to be operable and the diesel generator associated with the operable train is operable.

If the system is not made fully operable within 7 days, Amendment No. 42, 50, 51, 57, 112, 144, 151, 161,-170. 215 3/4.7-1 5

LIMITING CONDITIONS FOR OPERATION SURVEILLANCE REQUIREMENTS 3.7 CONTAINMENT SYSTEMS (CONT) 4.7 CONTAINMENT SYSTEMS (Cont) i) perform surveillance 4.7.B.2.b.4 for the operable CRHEAF every 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> OR ii) suspend movement of recently irradiated fuel assemblies in secondary containment and initiate actions to suspend OPDRVs. Any fuel assembly movement in C. Secondarv Containment progress may be completed.

1. Each refueling outage prior to refueling, C. Secondary Containment secondary containment capability shall be demonstrated to maintain 1/4 inch of

1. Secondary containment shall be water vacuum under calm wind (5 mph)

OPERABLE when in the Run, Startup conditions with a filter train flow rate of and Hot Shutdown MODES, during not more than 4000 cfm.

movement of recently irradiated fuel assemblies in the secondary containment, and during operations with a potential for draining the reactor vessel (OPDRVs).

2. a.With Secondary Containment inoperable when in the Run, Startup and Hot Shutdown MODES, restore Secondary Containment to OPERABLE status within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />.

b. Required Action and Completion Time of 2.a not met, be in HOT Shutdown in 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> AND Cold Shutdown within 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />.

c. With Secondary Containment inoperable during movement of recently irradiated fuel assemblies in the secondary containment and during OPDRVs, immediately:

1. Suspend movement of recently irradiated fuel assemblies in the secondary containment.

AND I

2. Initiate actions to suspend OPDRVs.

Amendment No. 0, 161,164, 215 3/4.7-1 6

BASES:

3/4.7 CONTAINMENT SYSTEMS (Cont)

B.1 Standby Gas Treatment System (Cont)

Tests of impregnated charcoal identical to that used in the filters indicate that a shelf life of five years leads to only minor decreases in methyl iodide removal efficiency.

Hence, the frequency of laboratory carbon sample analysis is adequate to demonstrate acceptability. Since adsorbers must be removed to perform this analysis this frequency also minimizes the system out of service time as a result of surveillance testing. In addition, although the halogenated hydrocarbon testing is basically a leak test, the adsorbers have charcoal of known efficiency and holding capacity for elemental iodine and/or methyl iodide, the testing also gives an indication of the relative efficiency of the installed system. The 31 day requirement for the ascertaining of test results ensures that the ability of the charcoal to perform its designed function is demonstrated and known in a timely manner.

The required Standby Gas Treatment System flow rate is that flow, less than or equal to 4000 CFM which is needed to maintain the Reactor Building at a 0.25 inch of water negative pressure under calm wind conditions. This capability is adequately demonstrated during Secondary Containment Leak Rate Testing performed pursuant to Technical Specification 4.7.C.1.c.

The test frequencies are adequate to detect equipment deterioration prior to significant defects, but the tests are not frequent enough to load the filters or adsorbers, thus reducing their reserve capacity too quickly. The filter testing is performed pursuant to appropriate procedures reviewed and approved by the Operations Review Committee pursuant to Section 6 of these Technical Specifications. The in-place testing of charcoal filters is performed by injecting a halogenated hydrocarbon into the system upstream of the charcoal adsorbers. Measurements of the concentration upstream and downstream are made. The ratio of the inlet and outlet concentrations gives an overall indication of the leak tightness of the system. A similar procedure substituting dioctyl phthalate for halogenated hydrocarbon is used to test the HEPA filters.

Pressure drop tests across filter and adsorber banks are performed to detect plugging or leak paths though the filter or adsorber media. Considering the relatively short times the fans will be run for test purposes, plugging is unlikely and the test interval of once per operating cycle is reasonable.

System drains and housing gasket doors are designed such that any leakage would be inleakage from the Standby Gas Treatment System Room. This ensures that there will be no bypass of process air around the filters or adsorbers.

Only one of the two Standby Gas Treatment Systems (SBGTS) is needed to maintain the secondary containment at a 0.25 inch of water negative pressure upon containment isolation. If one system is made or found to be inoperable, there is no immediate threat to the containment system performance and reactor operation or refueling activities may continue while repairs are being made. In the event one SBGTS is inoperable, the redundant system's active components will be verified to be operable within 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />. This substantiates the availability of the operable system and justifies continued reactor or refueling operations.

As discussed in Bases Section B3/4.7.C "Secondary Containment", SGTS is not required to be operable during movement of irradiated fuel assemblies that have been allowed to decay for the minimum specified decay period i.e., no longer "recently irradiated".

Revision 215 B3/4.7-1 0

BASES:

3/4.7 CONTAINMENT SYSTEMS (Cont) 6.1 Standby Gas Treatment System (Cont)

During movement of recently irradiated fuel, if one train of SGTS is made or found to be inoperable and the inoperable train is not restored to operable status within the required completion time, the operable train should immediately be placed in operation.

This action ensures that the remaining train is operable, that no failures that could prevent automatic actuation have occurred, and that any other failure would be readily detected. An alternative is to suspend movement of recently irradiated fuel, thus, placing the plant in a condition that minimizes risk. If both trains of SBGTS are inoperable, the plant is brought to a condition where the SBGTS is not required.

6.2 Control Room High Efficiency Air Filtration System The Control Room High Efficiency Air Filtration System is designed to filter intake air for the control room atmosphere during conditions when normal intake air may be contaminated. Following manual initiation, the Control Room High Efficiency Air Filtration System is designed to position dampers and start fans which divert the normal air flow through charcoal adsorbers before it reaches the control room.

High Efficiency Particulate Air (HEPA) filters are installed before the charcoal adsorbers to prevent clogging of the iodine adsorbers. The charcoal adsorbers are installed to reduce the potential intake of radioiodine to the control room. A second bank of HEPA filters is installed downstream of the charcoal filter.

The in-place test results should indicate a system leak tightness of less than 0.1%

bypass leakage for the charcoal adsorbers and a HEPA efficiency of at least 99%

removal of cold DOP particulates. The laboratory carbon sample test results should indicate a methyl iodide removal efficiency of at least 97.5% for expected accident conditions. Tests of impregnated charcoal identical to that used in the filters indicate that a shelf life of five years leads to only minor decreases in methyl iodine removal efficiency. Hence, the frequency of laboratory carbon sample analysis is adequate to demonstrate acceptability. Since adsorbers must be removed to perform this analysis, this frequency also minimizes the system out of service time as a result of surveillance testing. In addition, although the halogenated hydrocarbon testing is basically a leak test, the adsorbers have charcoal of known efficiency and holding capacity for elemental iodine and/or methyl iodide, the testing also gives an indication of the relative efficiency of the installed system. The 31-day requirement for the ascertaining of test results ensures that the ability of the charcoal to perform its designed function is demonstrated and known in a timely manner.

Determination of the system pressure drop once per operating cycle provides indication that the HEPA filters and charcoal adsorbers are not clogged by excessive amounts of foreign matter and that no bypass routes through the filters or adsorbers had developed. Considering the relatively short times the systems will be operated for test purposes, plugging is unlikely and the test interval of once per operating cycle is reasonable.

The test frequencies are adequate to detect equipment deterioration prior to significant defects, but the tests are not frequent enough to load the filters or adsorbers, thus reducing their reserve capacity too quickly. The filter testingis performed pursuant to appropriate procedures reviewed and approved by the Operations Review Committee pursuant to Section 6 of these Technical Specifications. The in-place testing of charcoal filters is performed by injecting a halogenated hydrocarbon into the system upstream of the charcoal adsorbers. Measurements of the concentration upstream and Revision 215 B3/4.7-1 1 1

BASES:

3/4.7 CONTAINMENT SYSTEMS (Cont) downstream are made. The ratio of the inlet and outlet concentrations gives an overall indication of the leak tightness of the system. A similar procedure substituting dioctyl phthalate for halogenated hydrocarbon is used to test the HEPA filters.

B.2 Control Room High Efficiency Air Filtration System (Cont)

Air flow through the filters and charcoal adsorbers for 15 minutes each month assures operability of the system. Since the system heaters are automatically controlled, the air flowing through the filters and adsorbers will be <70% relative humidity and will have the desired drying effect.

If one train of the system is made or found to be inoperable, there is no immediate threat to the control room, and reactor operation may continue for a limited period of time while repairs are being made. In the event one CRHEAF train is inoperable, the redundant system's active components will be verified to be operable within 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />. During movement of recently irradiated fuel in a refueling outage, if the inoperable train is not restored to operable status within the required completion time, movement of recently irradiated fuel may continue provided the operable CRHEAF train is placed in the pressurization mode daily. This action ensures that the remaining train is operable, that no failures that would prevent actuation will occur, and that any active failure will be readily detected. An alternative is to suspend movement of recently irradiated fuel. If both trains of the CRHEAF system are inoperable, the reactor will be brought to a condition where the Control Room High Efficiency Air Filtration System is not required.

As discussed in Bases Section B3/4.7.C "Secondary Containment", CRHEAFS is not required to be operable during movement of irradiated fuel assemblies that have been allowed to decay for the minimum specified decay period i.e., no longer "recently irradiated".

C. Secondary Containment The secondary containment is designed to minimize any ground level release of radioactive materials that might result from a serious accident. The reactor building provides secondary containment during reactor operation, when the drywell is sealed and in service; the reactor building provides primary containment during periods when the reactor is shutdown, the drywell is open, and activities are ongoing that require secondary containment to be operable. Because the secondary containment is an integral part of the complete containment system, secondary containment is required at all times that primary containment is required as well as during movement of "recently irradiated" fuel and during operations with the potential to drain the reactor vessel (OPDRVs).

There are two principal accidents for which credit is taken for secondary containment operability. These are a loss of coolant accident (LOCA) although not specifically evaluated for alternate source term methodology and a fuel handling accident involving "recently irradiated" fuel. The secondary containment performs no active function in response to each of these limiting events; however, its leak tightness is required to ensure that the release of radioactive materials from primary containment is restricted to those leakage paths and associated leakage rates assumed in the accident analysis and that fission products entrapped within the secondary containment structure will be treated by the Standby Gas Treatment System (SGTS) prior to discharge to the environment.

Revision 215 B3/4.7-12 I I

BASES:

3/4.7 CONTAINMENT SYSTEMS (Cont)

In addition to these limiting accidents, OPDRVs can be postulated to cause a fission product release. During movement of recently irradiated fuel and OPDRVs, secondary containment would be the only barrier to a release to the environment. Therefore, movement of recently irradiated fuel and OPDRVs must be immediately suspended if the secondary containment is inoperable. Suspension of these activities shall not preclude completing an action that involves moving a component to a safe position.

Also, action must be immediately initiated to suspend OPDRVs to minimize the probability of a vessel drain down and subsequent potential for fission product release.

Actions must continue until OPDRVs are suspended.

An operable secondary containment provides a control volume into which fission products that bypass or leak from primary containment, or are released from the reactor coolant pressure boundary components located in secondary containment can be diluted and processed prior to release to the environment. For the secondary containment to be considered operable, it must have adequate leak tightness to ensure that the required vacuum can be established and maintained.

If secondary containment is inoperable (when required to be operable), it must be restored to operable status Within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />. The 4 hour4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> completion time provides a period of time to correct the problem that is commensurate with importance of maintaining secondary containment during Run, Startup, and Hot Shutdown' modes.

This time period also ensures that the probability of an accident (requiring secondary containment operability) occurring during periods where secondary containment is inoperable is minimal.

If secondary containment cannot be restored to operable status within the required completion time, the plant must be brought to a mode in which the LCO does not apply.

To achieve this status during power operation, the plant must be brought to at least Hot Shutdown within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and to Cold Shutdown within 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />. The allowed completion times are reasonable, based on operating experience, to reach the required plant conditions from full power condition in an orderly manner and without challenging plant systems.

The Fuel Handling Accident (FHA) analysis is based on 10 CFR 50.67 and R.G.

1.183 Alternate Source Term Methodology. This parametric analysis concluded that the calculated TEDE values to the control room occupants, the exclusion area boundary, and the low population zone are well below the allowable TEDE limits established in 10 CFR 50.67 without crediting Secondary Containment, SGTS and CRHEAFS as long as a the fuel is allowed to decay for at least 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> following reactor shutdown.

As a result, "recently irradiated" fuel is defined as fuel that has occupied part of a critical reactor core within the previous 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, i.e. reactor fuel that has decayed less than 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> following reactor shutdown. Each fuel cycle, prior to the refueling outage, the decay period that must elapse prior to movement of irradiated fuel in the core will be re-evaluated to ensure the appropriate, minimum decay period is enforced to maintain the validity of the FHA dose consequence analysis.

Therefore, SGTS, CRHEAFS, and Secondary Containment are not required to be operable during movement of decayed irradiated fuel that is no longer is considered "recently irradiated". Conversely, Secondary Containment, SGTS, and CRHEAFS are required to be operable during movement of recently irradiated fuel assemblies.

Revision 215 133/4.7-1 3

BASES:

3/4.7 CONTAINMENT SYSTEMS (Cont)

Initiating reactor building isolation and operation of the standby gas treatment system to maintain at least a 1/4 inch of water negative pressure within the secondary containment provides an adequate test of the operation of the reactor building isolation valves, leak tightness of the reactor building and performance of the standby gas treatment system.

Functionally testing the initiating sensors and associated trip channels demonstrates the capability for automatic actuation. Performing these tests prior to refueling will demonstrate secondary containment capability prior to the time the primary containment is opened for refueling. Periodic testing gives sufficient confidence of reactor building integrity and standby gas treatment system performance capability.

Revision 215 133/4.7-1 4 i