ML022630284

Technical Specifications, Remove Existing Scram Function & Group 1 Isolation Valve Closure Functions of Main Steam Line Radiation Monitors

ML022630284
Person / Time
Site:	Vermont Yankee
Issue date:	09/18/2002
From:	NRC/NRR/DLPM/LPD1
To:	Vermont Yankee
References
TAC MB4610
Download: ML022630284 (6)

Text

VYNPS TABLE 3.1.1 (Cont ' d)

REACTOR PROTECTION SYSTEM (SCRAM) INSTRUMENT REQUIREMENTS Required ACTIONS When Minimum Number Minimum Modes in Which Functions Must Operating Conditions For Trip Settings be Operating Instrument Operation And Allowable Channels Per Are Not Trip Function Deviations Refuel (1) Startup Run Trip System (2) Satisfied (3)

9. Deleted

10. Main steamline <10% valve x 4 A or C isolation valve closure closure (POS-2-80A-A1,BI POS-2-86A-A1,BI POS-2-80B-Al,B2 POS-2-86B-AI,B2 POS-2-80C-A2,B1 POS-2-86C-A2,BI POS-2-80D-A2,B2 POS-2-86D-A2,B2)

11. Turbine control (9) (10) x 2 A or D valve fast closure (PS- (37-40))

12. Turbine stop valve <10% valve(10) x 2 A or D closure closure (SVOS (1-4))

212 22 Amendment No. 4-4, 4-84,

VYNPS TABLE 3.1.1 NOTES (Cont'd)

Instrument

3. When the requirements in the column "Minimum Number of Operating System" cannot be met for one system, that system shall be Channels Per Trip If the requirements cannot be met for both trip systems, the tripped.

appropriate ACTIONS listed below shall be taken:

of all a) Initiate insertion of operable rods and complete insertion operable rods within four hours.

"Startup/Hot b) Reduce power level to IRM range and place mode switch in the Standby" position within eight hours.

within 8 c) Reduce turbine load and close main steam line isolation valves hours.

d) Reduce reactor power to less than 30% of rated within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />.

4. "W" is percent rated two loop drive flow where 100% rated drive flow is that flow equivalent to 48 x 106 lbs/hr core flow. AW is the difference between same core flow. This the two loop and single loop drive flow at the loop operation. AW = 0 for difference must be accounted for during single two recirculation loop operation.

per level

5. To be considered operable an APRM must have at least 2 LPRM inputs A, C, D, and F and at least a total of 13 LPRM inputs, except that channels APRM Cabinet plus one additional may lose all LPRM inputs from the companion LPRM input and still be considered operable.

provides

6. The top of the enriched fuel has been designated as 0 inches and common reference level for all vessel water level instrumentation.

7. Deleted.

8. Deleted.

trip shall be

9. Channel signals for the turbine control valve fast closure event or evencs which cause the control valve fast derived from the same closure.

scram

10. Turbine stop valve closure and turbine control valve fast closure signals may be bypassed at <30% of reactor Rated Thermal Power.

11. Not used.

switch to be

12. While performing refuel interlock checks which require the mode need not be operable provided:

in Startup, the reduced APRM high flux scram

a. The following trip functions are operable:

1. Mode switch in shutdown,

2. Manual scram,

3. High flux IRM scram

4. High flux SRM scram in noncoincidence,

5. Scram discharge volume high water level, and;

b. No more than two (2) control rods withdrawn. The two (2) control rods that can be withdrawn cannot be face adjacent or diagonally adjacent.

4-4, -, -, 46 64, , 94,-4, 464, -- 4, 446, 44, 212 24 Amendment No. 4e,

VYNPS TABLE 4.1.1 SCRAM INSTRUMENTATION AND LOGIC SYSTEMS FUNCTIONAL TESTS MINIMUM FUNCTIONAL TEST FREQUENCIES FOR SAFETY INSTRUMENTATION, LOGIC SYSTEMS AND CONTROL CIRCUITS Group(3) Functional Test(7) Minimum Frequency (4)

Instrument Channel A Place Mode Switch in Shutdown Each Refueling Outage Mode Switch in Shutdown A Trip Channel and Alarm Every 3 Months Manual Scram IRM 5 Before Each Startup & Weekly High Flux C Trip Channel and Alarm( )

During Refueling(6)

C Trip Channel and Alarm Before Each Startup & Weekly Inoperative During Refueling(6)

APRM Every 3 Months High Flux B Trip Output Relays(5) Before Each Startup & Weekly High Flux (Reduced)

B Trip Output Relays(5)

During Refueling(6)

Every 3 Months Inoperative B Trip Output Relays B

Every 3 Months Flow Bias Trip Output Relays(5)

B Trip Channel and Alarm(5) Every 3 Months High Reactor Pressure 5 Every 3 Months B Trip Channel and Alarm( )

High Drywell pressure Every 3 Months B Trip Channel and Alarm(5)

Low Reactor Water Level(2)(8)

Every 3 Months B Trip Channel and Alarm(5)

High Water Level in Scram Discharge Volume A Trip Channel and Alarm Every 3 Months Main Steam Line Iso. Valve Closure Trip Channel and Alarm Every 3 Months A

Turbine Con. Valve Fast Closure Trip Channel and Alarm Every 3 Months A

Turbine Stop Valve Closure Once each week (9)

A Trip Channel and Alarm Scram Test Switch (5A-S2(A-D))

Trip Channel and Alarm Every 6 Months A

First Stage Turbine Pressure Permissive (PS-5-14(A-D))

25 Amendment No. 4-, 2-, -s-, 7-, *, 4-84, 212

VYNPS TABLE 4.1.1 NOTES

1. Not used and reactor

2. An instrument check shall be performed on reactor water level pressure instrumentation once per day.

3. A description of the three groups is included in the basis of this Specification.

required to be

4. Functional tests are not required when the systems are not If tests are missed, they shall be performed operable or are tripped.

prior to returning the systems to an operable status.

Test

5. This instrumentation is exempted from the Instrument Functional This Instrument Functional Test will consist of Definition (1.G.).

electrical signal into the measurement channels.

injecting a simulated

6. Frequency need not exceed weekly.

as indicated.

7. A functional test of the logic of each channel is performed placing the mode switch in shutdown each refueling outage This coupled with constitutes a logic system functional test of the scram system.

the

8. The water level in the reactor vessel will be perturbed and changes will be monitored. This test will be corresponding level indicator performed every month.

week by either

9. The automatic scram contactors shall be exercised once every switches or performing a functional test of any using the RPS channel test If the contactors are exercised using a automatic scram function.

using the RPS channel functional test of a scram function, the weekly test shall test switch is considered satisfied. The automatic scram-contactors also be exercised after maintenance on the contactor_.

26 Amendment No -, *5, ý4, , 212

VYNPS TABLE 4.1.2 SCRAM INSTRUMENT CALIBRATION CHANNELS MINIMUM CALIBRATION FREQUENCIES FOR REACTOR PROTECTION INSTRUMENT Calibration Standard(4) Minimum Frequency(2)

Instrument Channel Group(1)

High Flux APRM Once Every 7 Days B Heat Balance Output Signal B Heat Balance Once Every 7 Days Output Signal (Reduced) (7) Refueling Outage B Standard Pressure and Voltage Flow Bias Source Using TIP System Every 2,000 MWD/T average LPRM (LPRM ND-2-I-104(80)) core exposure (8)

Standard Pressure Source Once/Operating Cycle High Reactor Pressure B Standard Pressure Source Every 3 Months A

Turbine Control Valve Fast Closure Once/Operating Cycle B Standard Pressure Source High Drywell Pressure B Water Level Once/Operating Cycle High Water Level in Scram Discharge Volume B Once/Operating Cycle Standard Pressure Source Low Reactor Water Level (6) Refueling Outage A

Turbine Stop Valve Closure A Pressure Source Every 6 Months and After First Stage Turbine Pressure Refueling Permissive (PS-5-14(A-D))

(6) Refueling Outage A

Main Steam Line Isolation Valve Closure 27 Amendment No. 4-4, 22-4, .5&, 4*- ýý , , a-84, a-9-1r, 212

VYNPS TABLE 4.1 2 NOTES

1. A description of the three groups is included in the bases of this Specification.

are not required to be

2. Calibration tests are not required when the systems shall be performed If tests are missed, they operable or are tripped.

status.

prior to returning the systems to an operable

3. Deleted.

and calibration,

4. Response time is not part of the routine instrument check but will be checked every operating cycle.

5. Does not provide scram function.

6. Physical inspection and actuation.

to overlap during each startup

7. The IRM and SRM channels shall be determined MODE and the IRM and APRM channels after entering the STARTUP/HOT STANDBY during each controlled shutdown, if not shall be determined to overlap performed within the previous 7 days.

is performed within 1.25

8. The specified frequency is met if the calibration measured from the previous performance.

times the interval specified, as 28 Amendment ITo. 241, *-8G, 4-+/-9, 212

VYNPS BASES: 3.1 (Cont'd)

The main steam line isolation valve closure scram is set to scram when the isolation valves are 10 percent closed from full open in 3-out-of-4 lines.

This scram anticipates the pressure and flux transient, which would occur when the valves close. By scramming at this setting, the resultant transient is insignificant.

A reactor mode switch is provided which actuates or bypasses the various scram functions appropriate to the particular plant operating status.

The manual scram function is active in all modes, thus providing for manual means of rapidly inserting control rods during all modes of reactor operation.

The IRM system provides protection against short reactor periods and, in conjunction with the reduced APRM system provides protection against excessive power levels in the startup and intermediate power ranges. A source range monitor (SRM) system is also provided to supply additional neutron level information during startup and can provide scram function with selected shorting links removed during refueling. Thus, the IRM and the reduced APRM are normally required in the startup mode and may be required in the refuel mode. During some refueling activities which require the mode switch in startup; it is allowable to disconnect the LPRMs to protect them from damage during under vessel work. In lieu of the protection provided by the reduced APRM scram, both the IRM scram and the SRM scram in noncoincidence are used to provide neutron monitoring protection against excessive power levels. In the power range, the normal APRM system provides required protection. Thus, the IRM system and 15%

APRM scram are not required in the run mode.

If an unsafe failure is detected during surveillance testing, it is desirable to determine as soon as possible if other failures of a similar type have occurred and whether the particular function involved is still operable or capable of meeting the single failure criteria. To meet the requirements of Table 3.1.1, it is necessary that all instrument channels in one trip system be operable to permit testing in the other trip system.

Thus, when failures are detected in the first trip system tested, they would have to be repaired before testing of the other system could begin.

In the majority of cases, repairs or replacement can be accomplished quickly. If repair or replacement cannot be completed in a reasonable time, operation could continue with one tripped system until the surveillance testing deadline.

Amendment No. £-2, -7, &- . , 212 31

VYliPS 4 2 SURVEILLANCE REQUIREMENTS 3.2 LIMITING CONDITIONS FOR OPERATION D. Off-Gas System Isolation D. Off-Gas System Isolation Instrumentation and logic During reactor power systems shall be operation, the functionally tested and instrumentation that calibrated as indicated in initiates isolation of the Table 4.2.4.

off-gas system shall be operable in accordance with Table 3.2.4.

E. Control Rod Block Actuation E. Control Rod Block Actuation Instrumentation and logic During reactor power systems shall be operation the functionally tested and instrumentation that calibrated as indicated in initiates control rod block Table 4.2.5.

shall be operable in accordance with Table 3.2.5.

F. Mechanical Vacuum Pump F. Mechanical Vacuum Pump Isolation Instrumentation Isolation Instrumentation The High Main Steam Line When the reactor is in the Radiation Trip Function for RUN or STARTUP/HOT STANDBY mechanical vacuum pump Mode and the mechanical isolation shall be checked, vacuum pump is in service, functionally tested and four (4) channels of the calibrated as indicated in High Main Steam Line Surveillance Requirements Radiation Trip Function for 4.2.F.1, 2, 3, 4 and 5.

mechanical vacuum pump isolation shall be operable, When a channel is placed in except as provided below. an inoperable status solely for performance of required

1. With one or more channels surveillances, entry into inoperable, within 12 associat'-d Limiting hours: Conditions for Operation and required actions may be

a. Restore the inoperable delayed for up to six (6) channel(s) to operable hours provided the associated status; or trip function maintains mechanical vacuum pump

b. Place the inoperable isolation capability.

channel(s) or associated trip system 1. Perform an instrument in the trip condition check once each day.

(not applicable if the inoperable channel is 2. Perform an instrument the result of an functional test once every inoperable mechanical three (3) months.

vacuum pump isolation valve).

35 Amendment No. 4,  ;-619 212

VYNPS 4 2 SURVEILLANCE REQUIREMENTS 3.2 LIMITING CONDITIONS FOR OPERATION

3. Perform an instrument

2. If the required action and calibration, except for associated completion time the radiation detectors, of Specification 3.2.F.1 is using a current source not met, within the once every three (3) following 12 hour1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />s: months. The trip setting shall be 5 3.0 times

a. Isolate the mechanical background at rated vacuum pump; or thermal power.

b. Isolate the main steam 4. Perform an instrument lines; or calibration using a radiation source once each

c. Place the reactor in refueling outage.

the SHUTDOWN Mode.

5. Perform a logic system functional test, including mechanical vacuum pump isolation valve, once each operating cycle.

G. Post-Accident Instrumentation G. Post-Accident Instrumentation The post-accident During reactor power operation, instrumentation shall be the instrumentation that functionally tested and displays information in the calibrated in accordance with Control Room necessary Table 4.2.6.

for the operator to initiate and control the systems used during and following a postulated accident or abnormal operating condition shall be operable in accordance with Table 3.2.6.

H. Drywell to Torus AP H. Drywell to Torus AP Instrumentation Instrumentation The Drywell to Torus AP

1. During reactor power Instrumentation shall be operation, the Drywell to calibrated once every six Torus AP Instrumentation months and an instrument (recorder #1-156-3 and check will be made once per 6

instrument DPI-I-158- ) shift.

shall be operable except as specified in 3.2.H.2.

2.From and after the date that one of the Drywell to Torus AP instruments is made or found to be inoperable for any reason, reactor operation is permissible only during the succeeding thirty days unless the instrument is 36 S4, -4&, 4-ý, 9&, !1!, 4--2-, , 212 Amendment No.

VYNPS LIMITING CONDITIONS FOR 4.2 SURVEILLANCE REQUIREMENTS 3 2 OPERATION sooner made operable. If both instruments are made or found to be inoperable, and indication cannot be restored within a six hour period, an orderly shutdown shall be initiated and the reactor shall be in a hot shutdown condition in six hours and a cold shutdown condition in the following eighteen hours.

I. Recirculation Pump Trip I. Recirculation Pump Trip Instrumentation Instrumentation The Recirculation Pump Trip During reactor power Instrumentation shall be operation, the Recirculation functionally tested and Pump Trip Instrumentation calibrated in accordance with shall be operable Table 4.2.1.

in accordance with Table 3.2.1.

J. Deleted J. Deleted K. Degraded Grid Protective K. Degraded Grid Protective System System The emergency bus During reactor power undervoltage instrumentation operation, the emergeacy bus shall be functionally tested undervoltage instrumentation and calibrated in accordance shall be operable in with Table 4.2.8.

accordance with Table 3.2.8.

L. Reactor Core Isolation L. Reactor Core Isolation Cooling System Actuation Cooling System Actuation Instrumentation and Logic When the Reactor Core Systems shall be Isolation Cooling System is functionally tested and required in accordance with calibrated as indicated in Specification 3.5.G, the Table 4.2.9.

instrumentation which initiates actuation of this system shall be operable in accordance with Table 3.2.9.

37 Amendment No. r, , 4, 4a, 444-, 212

VYNPS TABLE 3.2.2 PRIMARY CONTAINMENT ISOLATION INSTRUMENTATION Required ACTION When Minimum Number of Minimum Conditions Operable Instrument For Operation Are Channels per Trip Trip Function Trip Setting Not Satisfied (Note 2)

System 2 Low-Low Reactor Vessel Water >82.5" above the top of A (Notes 11,12) Level (LT-2-3-57A/B(S2), enriched fuel LT-2-3-58A/B(S2))

2 of 4 in each of High Main Steam Line Area <212OF B 2 channels Temperature (Notes 11,12) (TS-2-(121-124) (A-D))

2/steam line High Main Steam Line Flow <140t of rated flow B (Notes 11,12) (DPT (116-119) (A-D) (M))

>800 psig B 2 Low Main Steam Line Pressure (Notes 1,11,12) (PS-2-134(A-D))

2 High Main Steam Line Flow <40i of rated flow (Notes 6,11,12) (DPT-2-116A, 117B, 118C, 119D (Sl))

2 Low Reactor Vessel Water Level Same as Reactor A (LT-2-3-57A/B(M), Protection System (Notes 11,12)

LT-2-3-58A/B(M))

I 2 High Drywell Pressure Same as Reactor Protection System A

(Notes 11,12)

<12" Hg absolute A 2 Condenser Low Vacuum (Notes 10,11,12)

A 1 Trip System Logic G

,-6r,

• 212

,-8-& 45 Amendment No. 4, 4-&, ý84,

• VYNlPS TABLE 3.2.2 NOTES

1. The main steam line low pressure need be available only in the "Run" mode.

2. If the minimum number of operable instrument channels are not available for one trip system, that trip system shall be tripped. If the minimum number of operable instrument channels are not available for both trip systems, the appropriate actions listed below shall be taken:

A. Initiate an orderly shutdown and have reactor in the cold shutdown condition in 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

B. Initiate an orderly load reduction and have reactor in "Hot Standby" within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />.

3. Close isolation valves in system and comply with Specification 3.5.

4. Deleted.

5. One trip system arranged in a one-out-of-two twice logic.

6. The main steam line high flow is available only in the "Refuel,"

"Shutdown," and "Startup" modes.

7. Deleted.

8. Deleted.

9. Deleted.

10. A key lock switch is provided to permit the bypass of this trip function to enable plant startup and shutdown when the condenser vacuum is greater than 12 inches Hg absolute provided that both turbine stop and bypass valves are closed.

11. When a channel, and/or the affected primary containment isolation valve, is placed in an inoperable status solely for performance of required instrumentation surveillances, entry into associated Limiting Conditions for Operation and required ACTIONS may be delayed for up to 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> provided the associated Trip Function maintains isolation capability.

12. Whenever Primary Containment integrity is required by Specification 3.7.A.2, there shall be two operable or tripped trip systems for each Trip Function, except as provided for below:

A. With one or more automatic functions with isolation capability not maintained restore isolation capability in 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> or take the ACTION required by Table 3.2.2.

B. With one or more channels inoperable, place the inoperable channels (s) in the tripped condition within:

1) 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> for trip functions common to RPS instrumentation, and

2) 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> for trip functions not common to RPS instrumentation, or, initiate the ACTION required by Table 3.2.2.

, 212 48 Amendment No. 4, 49-, 4:1-,

VYNPS TABLE 4.2.2 MINIMUM TEST AND CALIBRATION FREQUENCIES PRIMARY CONTAINMENT ISOLATION INSTRUMENTATION Calibration(8) Instrument Check Trip Function Functional Test(8)

Once Each Day Every Three Months Once/Operating Cycle Low-Low Reactor Vessel Water Level Every Three Months Each Refueling Outage High Steam Line Area Temperature Once Each Day Every Three Months Once/Operating Cycle High Steam Line Flow Every Three Months Every Three Months Low Main Steam Line Pressure Every Three Months Once/Operating Cycle Low Reactor Vessel Water Level Once Each Day Every Three Months Once/Operating Cycle High Drywell Pressure Every Three Months Every Three Months Condenser Low Vacuum Once/Operating Cycle Once/Operating Cycle Trip System Logic (Note 2) (Note 3) 64 Amendment No. ,, "4, 4-0-, , ý, 212

VYNPS TABLE 4.2 NOTES

1. Not used.

2. During each refueling outage, simulated automatic actuation which opens all pilot valves shall be performed such that each trip system logic can be verified independent of its redundant counterpart.

3. Trip system logic calibration shall include only time delay relays and timers necessary for proper functioning of the trip system.

4. This instrumentation is excepted from functional test definition. The functional test will consist of injecting a simulated electrical signal into the measurement channel.

5. Deleted.

6. Deleted.

I . Deleted.

8. Functional tests and calibrations are not required when systems are not required to be operable.

9. The thermocouples associated with safety/relief valves and safety valve position, that may be used for back-up position indication, shall be verified to be operable every operating cycle.

10. Separate functional tests are not required for this instrumentation.

The calibration and integrated ECCS tests which are performed once per operating cycle will adequately demonstrate proper equipment operation.

11. Trip system logic functional tests will include verification of operation of all automatic initiation inhibit switches by monitoring relay contact movement. Verification that the manual inhibit switches prevent opening all relief valves will be accomplished in conjunction with Section 4.5.F.1.

12. Trip system logic testing is not applicable to this function. If the required surveillance frequency (every Refueling Outage) is not met, functional testing of the Reactor Mode Switch-Shutdown Position function shall be initiated within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> after the reactor mode switch is placed in Shutdown for the purpose of commencing a scheduled Refueling Outage.

13. Includes calibration of the RBM Reference Downscale function (i.e., RBM upscale function is not bypassed when >30% Rated Thermal Power).

Amendment No. 6-, 9, +/-8-5, +/-*4, i-6-,-i-, e 212 74

VYN PS BASES: 3.2 (Cont'd) line and For the complete circumferential break of 28-inch recirculation ECCS initiation and primary system with the trip setting given above, criteria. The isolation are initiated in time to meet the above the full range of spectrum breaks and meets the instrumentation also covers above criteria.

to the water level The high drywell pressure instrumentation is a backup ECCS, it causes isolation of instrumentation, and in addition to initiating break For the complete circumferential Group 2, 3, and 4 isolation valves. at about will initiate ECCS operation discussed above, this instrumentation the results thus, the same time as the low-low water level instrumentation, valves including given above are applicable here also. Certain isolation the TIP blocking valves, CAD inlet and outlet, drywell vent, purge and sump However, since high drywell valves are isolated on high drywell pressure.

non-safety-related causes, such as not pressure could occur as the result of is not complete system isolation venting the drywell during startup, to and only certain valves are required desirable for these conditions for the full close. The water level instrumentation initiates protection a trip of certain primary spectrum of loss of coolant accidents and causes system isolation valves.

a means of measuring steam Venturis are provided in the main steam lines as mass inventory from the vessel during a flow and also limiting the loss of steam line break accident. In addition to monitoring steam flow, instrumentation is provided which causes a trip of Group 1 isolation valves.

to detect a break in the main The primary function of the instrumentation is For the worst case steam line, thus only Group 1 valves are closed.

the drywell, this trip setting of accident, main steam line break outside conjunction with the flow limiters and 140 percent of rated steam flow in inventory loss such that fuel main steam line valve closure limit the mass 0 less than 1295 F and release is not uncovered, cladding temperatures remain 10CFRI00.

of radioactivity to the environs is well below in the main steam line Temperature monitoring instrumentation is provided tunnel to detect leaks in this area. Trips are provided on this of Group 1 isolation valves.

instrumentation and when exceeded cause closure to detect leaks of the order Its setting of ambient plus 95OF is low enough the entire spectrum of of 5 to 10 gpm; thus, it is capable of covering For large breaks, it is a backup to high steam flow instrumentation breaks.

with the resultant small release of discussed above, and for small breaks, of 10CFR100 are exceeded.

radioactivity, gives isolation before the limits (MVP) is assumed in the Isolation of the condenser mechanical vacuum pump The MVP isolation (CRDA).

safety analysis for the control rod drop accident valve suction isolation instrumentation initiates closure of the MVP exceed a radiation monitors following events in which main steam line Monitor trip setting A High Main Steam Line Radiation predetermined value.

rated thermal power (RTP) is as for MVP isolation of

• 3 times background at of spurious trips from nitrogen-16 low as practicable without consideration and other operational occurrences.

spikes, instrument instabilities products in the limits the release of fission Isolating the condenser MVP event of a CRDA.

when main steam line Pressure instrumentation is provided which tripsinstrumentation results in A trip of this pressure drops below 800 psig.

closure of Group 1 isolation valves. In the refuel, shutdown, and startup when main steam line flow exceeds 40%

modes, this trip function is provided of rated capacity. This function is provided primarily to provide which would cause the protection against a pressure regulator malfunction 2

212 76

&l, S4, '4,  ;-1, BVV4 (-4 S;' ,

Amendment No. -,

VYNPS BASES: 3.2 (Cont'd)

Specification 3.2.G requires that the post-accident monitoring (PAM) instrumentation of Table 3.2.6 be operable during reactor power operation.

PAM instrumentation is not required to be operable during shutdown and refueling conditions when the likelihood of an event that would require PAM instrumentation is extremely low. The primary purpose of the PAM instrumentation is to display plant variables that provide information This required by the control room operators during accident situations.

information provides the necessary support for the operator to take the no automatic control is provided and that are manual actions for which required for safety systems to accomplish their safety functions for design basis accidents. The operability of the PAM instrumentation plant ensures that there is sufficient information available on selected and behavior following an parameters to monitor and assess plant status accident. This capability is consistent with the recommendations of Regulatory Guide 1.97, "Instrumentation for Light Water Cooled Nuclear Power Plants to Assess Plant and Environs Conditions During and Following an Accident."

to In most cases, Table 3.2.6 requires a minimum of two operable channels ensure that the operators are provided the information necessary to determine the status of the plant and to bring the plant to, and maintain it in, a safe condition following an accident. For the majority of parameters monitored, when one of the required channels is inoperable, the required inoperable channel must be restored to operable status within 30 days. The 30-day completion time is based on operating experience and of a takes into account the remaining operable channel (or in the case parameter that has only one required channel, an alternate means to monitor the parameter), the passive nature of the instrument (no critical the low automatic action is assumed to occur from these instruments), and probability of an event requiring PAM instrumentation during this interval.

If a PAM instrument channel has not been restored to an operable status within the specified interval, the required action is to prepare a written a

report to be submitted to the NRC within the following 14 days. When is required in accordance with the provisions of special written report the report will outline the preplanned alternate method of Table 3.2.6, plcýns and schedule for monitoring, the cause of the inoperability, and the restoring the instrumentation to an operable status. This action is appropriate in lieu of a shutdown requirement, since alternative actions are identified before loss of functional capability, and given the by likelihood of plant conditions that would require information provided this instrumentation.

are For the ma3ority of PAM instrumentation, when two required channels that is monitored by only one inoperable (or in the case of a parameter channel, the channel and an alternate means are inoperable), one channel status (or the required alternate means) should be restored to an operable days. The completion time of seven days is based on the within seven and relatively low probability of an event requiring PAM instrumentation the normal availability of alternate means to obtain the required information. Where specified, continuous operation with two required channels inoperable (or one channel and the required alternate means inoperable) is not acceptable after seven days. Therefore, restoration of one inoperable channel limits the risk that the PAM function will be in a degraded condition should an accident occur.

212 79 Amendment No. 4,

-6 , 4 , 4-I-, 4 4 4-r,4&, --

74, ,