ML20118B940

Proposed TS 3.7.5 Re Operability of Cooling Tower Cell & Increasing TS Temp Limit for Cooling Tower Vasin Water

ML20118B940
Person / Time
Site:	Seabrook
Issue date:	09/30/1992
From:	NORTH ATLANTIC ENERGY SERVICE CORP. (NAESCO)
To:
Shared Package
ML20118B936	List: ML20118B935 ML20118B939 ML20118B940
References
NUDOCS 9210080145
Download: ML20118B940 (20)

Text

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PLANT SYSTEMS ,

. 3/4.7.5 ULTIMATE HEAT SINK LIMITING CONDITION FOR OPERATION 3.7.5 The ultimate heat sink (VHS) shall be OPERABLE w';h:

a. A service water pumchouse water level at or above 5'-0", minus 36'-0" Mean Sea Level, USGS datum, and

b. A mechanical draf t cooling tower comprised of one cooling tower cell withoneOPERABLE4anandasewndcellwithtwoOPERABLE9ans,and a contained basin water level of equal to or greater than 42.15^ feat at a bulk average water temperature of less th6n or equal to 67-38 ,

and k'70

c. A portable tower makeup pump system stored to be OPERAB'.: for 30 days following a Safe Shutdown Earthquake.

APPLICABILITY: MODES 1, 2, 3, and 4.

ACTION:

a. With the service water pumphouse inoperable, restore the service water pumphouse to OPERABLE status within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />, or be in at least HOT STAN')BY within the next 5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> and in COLD- SHUTDOWN within the following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />. *

b. With the mechanical draft cooling tower inoperable, restore the cooling tower to OPERABLE status within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />, or be in at least HOT STANDBY within the next E hours c.d in COLD SHUTDOWN within the following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />. -

c. With the portable tower makeup pump system not stored to be OPERABLE, r^ store the portable tower makeup p;mp system to its required stored condition within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />, or declare the portable tower makeup pump system inoperable,

d. With the portacle tower makeup pump system inoperable, continue operation and notify the NRC with% 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> in accordant e with the procedure of 10 CFR 50.72 of actians or contingencies to ensure an adequate supply of makeup water to the mechanical draft cooling

• tower for a minimum of 30 days.

• With the cooling tower in operation with valves aligned for tunnel heat treat-ment, the tower basin level shall be maintained at greater than or equal to

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PLANT SYSTEMS

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'ULTIMATEHEATSINJ

, SURVEILLANCE REQUIREMENTS 3

-4.7.5 The ultimate heat sink shall be determinec OPERABLE:

a. At S.ast once per 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> by:

1) Verifying the water level in the service water pumpnouse to be at or abnve 5'-0", minus 36'-0" Mean Sea Level, and

2) Verifying the water in the mechanical draf t ccoling tower basin '

. to be greater than or equal to a level of 42.15 feet.

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b. At least once per week by verifying that the water in the mechanical _

draft cooling tower basin to be at a bulk average tempert,ture of less than or equal t 6 43 F.

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c. At least once per a. days by:

1) Starting from the c's il room each UHS cooling tower f an that is required to be 01 kABLE snd operating cach of those fans for at least 15 minutes, e..

2) Verifying that the portable tower makeup pumo systec is stored in it; design operational readiness state.

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• b " ' * " " " * 'Y' " 'r"'*f'^%>v *'/H Y. "r A4_ Ver4tftng% tem?&'ETE5MOfT547AFC$"fYo~rba Tower Actuation test signal, and

. 2) Verifying the portable tower makeup put.p develops a flow greater than or equal to 200 gpm on recirculation test flow. -

SEABROOK - UNIT 1 3/4 7-15 C  !

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' PLANT SYSTEMS l

BASES g

3/4.7.2 STEAM GENERATOR PRESSURE / TEMPERATURE LIMITATION The limitation on steam generator pressure and temperature ensures that the pressure-induced stresses in the steam generators do not exceed the maximum allowable fracture toughness stress limits. The limitations of 70 F and 200 psig are based on a steam generator RT NDT f 60 F and are sufficient to prevent brittle fracture 3/4.7.3 PRIMARY COMPONENT COOLING WATER SYSTEM The OPERABILITY cf the Primary Component Cooling Water System ensures that sufficient cooling capacity is available for continued operation of safety-related equipment during normal and accident conditions. The redundant cooling -

capacity of this system, assuming a single failure, is cons' tnt with the assumptions used in the safety analyses.

3/4.7.4 SEPLVICEWATERSYSTEM The Service Water System consisis of two independent loops, each of which -

can operate with either a service water pump train or a cooling tower pump train. The OPERABILITY of the Service Water System ensures that sufficient cooling capacity is available for continued operation of safety related equip-ment during normal and accident conditions. The redundant coolino capacity of P this system, assuming a single failure, is cansistent vith the assumptions -

h used in the safety analyses, which also assumes loss of either the cooling tower or ocean cooling.

3/4.7.5 ULTIMATE HEAT SINK The limitations on service water pumphouse level, and the OPERABILITY requirements for the mechanical draft cooling tower and the portable tower  %

makeup pump system, ensure that suffidient cooling capacity is available to either: (1) provide normal cooldown of the facility or (2) mitigate the effects of accident conditions within acceptable limits. This cooling capabil-ity is provided by the Atlantic Ocean except during loss of ocean tunnel water flow, when the cooling capability is provided by the mechanical draf t cooling tower with tower makeup using portable pumps.

The limitations on. minimum water level and the requirements for mechanical draf t cooling tower OPERABILITY are based on providing a 30-day cooling water supply to safety-related equipment without exceeding its design basis tempera-ture and is consistent with the recommendations of Regulaterv Guide 1.27, "Ulti ate Heat Sink for Nuclear Plants," March 1974.

3/4.7.6 CONTROL ROOM EMERGENCY MAKEUP AIR fu FILTRATION SUBSYSTEM The OPERABILITY of the Control Room Emergency Makeup Air and Filtration Subsystem ensures that: (1) the allogble 'emperature for continuous-duty rating for the equipment and instrumentation cooled by this system is not CD exceeded; and (2) the control room will remain habitable for operations SEJ' - UNIT 1 B 3/4 7-3

. .. . . - -.. . _ . . - - . - . ~ . . ~ . . . . . . . - . - . -_...... . . --.. - . . . - - . -. . - ,

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- INSERT-A The' Cooling Towcr is norrnally aligned to allow return flow to initially bypass the towcr .

sprays and return to.the basin. In addition, the control switches for the cooling tower fans

- are normally maintained in the " pull to lock" position. Upon receipt of a Tower Actuation -

Signal, the fans and sprays are manually operated as required. - This manual operation, which is gos .rned by procedures, ensures that ice does _not buildup on the cooling tower tile fill and fans. Manual action is sufficient to raaintain the cooling tower basin at a temperature which precludes equiprnent damage during the postulated design basis event. 1 4

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111. Hetype of proposed Channes See attached retype of proposed changes to Technical Specifications. The attached -

retype reflects the currently issued version of the Technical Specifications. Pending Technical Specification changes or Technical Specification changes issued subsequent .,

to this submittal are not reflected in the enclosed retype. The enclosed retype should be checked for continuity with the ctirrent Technical Specifications prior to issuance.

Revision bars are provided in the right hand margin to designate a change in the text.

No revision bars are utilized when the page is changed solely to accommodate the shifting of text due to additions or deletions.

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_______________._____m_____ _ _ _ . _ _ _ ____._._.

a PLANT-SYS'TEMS 3/4.7.5 --ULTIMATE HEAT SINK-L-lMITING CONDITION FOR OPERATION ~

3.7.5- The ultimate heat sink (UHS) shall be OPERABLE with:

a. A service water pumphouse water level'at or above 5'-0", minus 36'-0" Mean Sea Level, USGS datum, and

b. A mechanical draft cooling tower comprised of one cooling tower l I

cell with one OPERABLE ** fan and a second cell with'two OPERABLE _**

fans, and a contained basin water level of equal to or greater than 42.15* feet at a bulk average water temperature of less than or equal to 70*F, and

c. A portable tower makeup pump system stored to be OPERABLE for 30 days following a Safe Shutdown Earthquake.

APPL ICABILITY: MODES 1, 2, 3, and 4.

ACTION:

a. With the service water pumphouse inoperable, restore the service water pumphouse to OPERABLE status within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />, or be in at least HOT STANDBY within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in COLD SHUTDOWN within the following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />,

b. With the mechanical draft cooling tower-inoperable, restore the cooling. tower to OPERA 9LE status within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />, or be in at least .

HOT STANDBY within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in COLD SHUTD0"N within the following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />,

c. With the-portable tower makeup pump system not stored to be OPERABLE, restore the portable tower makeup _ pump system to its required stored condition within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />, or declare the portable tower makeup pump system inoperable.

d. With the portable tower makeup pump system inoperable, continue operation and notify the NRC within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> in accordance with the procedure of 10 CFR 50.72 of actions or contingencies to ensure an

-adequate supply of makeup water to the mechanical draft cooling tower for a minimum;of 30 days.

• With the cooling-tower in operation with valves aligned for tunnel heat treatment, the tower basin level shall be maintained at greater than or.

-equal to'40.55 feet..

-**A fan may be considered 0PERABLE-ifrit is capable of being manually started-from the main control board.

SEABROOK - UNIT 1 3/4 7-14 Amendment No.

4 . . . - ._. .

-PLANT SYSTEMS,-

L

- VLTIMATE HEAT SINK ,

i SURVEILLANCE PE0VIREMENTS ,.

~4.7.5 The ultimate heat sink : hall be determined OPERABLE:

a. At least once per 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> by:

1) Verifying the water level in the service water pumphnusa .o ^

be at or-above 5'-0", minus 36'-0" Mean Sea Level, ana

2) Verifying the water in the mechanical draft cooling tower basin to be greater than or equal to a level of 42.15 feet,

b. At least once per week by verifying that the water in the mechanical draft cooling tower basin to be at a bulk average temperature of less than or equal-to 70*F.

c. At least once per-31 days by:

1

1) Starting from the control room each UHS cooling tower fan l: that is required to be OPERABLE and operating each of those--

fans for at least 15 minutes, and

2) . Verifying that the portable tower makeup pump system is i stored in its design operational readiness state.

d. At least once per 18 months by:

1) Verifying that each automatic valve in the flow path actuates to its correct position on a Tower Actuation test signal, and

2) Verifying the portable tower makeup pump develops a flow _ t greater than or equal to 200 gpm on recirculation test- flow.

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, SEABROOK - UNIT 1 3/4 7-15 Amendment No.

l s .

g_ PL ANT SYSTEMS-BASES" _

J/4.7 2 STEAM GENERATOR PRESSURE / TEMPERATURE LIMITATI0fi The limitation on steam generator pressure and temperature ensures that the pressure-induced stresses in the steam generators do not exceed the maximum allowable fracture toughness stress limits. The limitations of 70"f and 200 psig are based on a steam generator RT.m of 60*F and are sufficient to prevent brittle fracture.

3/4.7.3 PRIMARY COMPONENT COOLING WATER SYSTFM The OPERABILITY of the Primary Component Cooling Water System ensures that sufficient cooling capacity is available for continued operation of safety-related equipment during normal and accident conditions. The redundant cooling capacity of this system, assuming a single failure, is consistent with -

the assumptions used in the safety analyses.

3/4,7.4 SERVICE WATER SYSTEM The Service Water System consists of two independent loops, each of-which-can operate with either a service water pump train or a cooling tower pump train. The OPERABILITY of the Service Water System ensures that sufficient cooling capacity is available for continued operation of safety-related equip-ment during normal and accident conditions. The redundant cooling capacity of this system, assuming a single failure, is consistent with the assumptions used in the safety analyses, which also assumes loss of either the cooling tower or.

ocean cooling.

3/4.7.5 ULTIMATE HEAT SINK The limitations on service water pumphouse level, and the OPERABILITY requirements for the mechanical draft cooling tower and the portable tower-is available to makeup either: pump)

(1 system, ensure that sufficient cooling capacityprovide normal cooldown "

of th effects of-accident conditions within acceptable limits. This cooling capabil-ity is provided by the Atlantic Ocean except during loss of ocean tunnel water flow, when the cooling- capability is provided by the-mechanical- draf t cooling tower with_ tower makeup using-portable pumps.

The-limitations on minimum water level and the requirements for mechanical draft cooling tower OPERABILITY are based on providing a 30-day cooling water supply to safety-related equipment without-exceeding its design basis temperature and is consistent with the recommendations of Regulatory-Guide 1.27, " Ultimate Heat Sink for Nuclear Plants," March 1974.

The cooling tower is normally aligned to allow return flow to initially-bypass thel tower sprays'and return to the basin. In addition, the control-switches for the cooling tower-fans are normally maint_ained in the " pull-to-

-lock" position. Upon receipt of a Tower Actuation Signal, the fans and. sprays are manually operated as required. This manual operation, which is governed by procedures, ensures that ice does not buildup on the cooling tower. tile fill and fans. Manual action is sufficient to--maintain the cooling tower basin at a temperature which_ precludes equipment damage during the postulated design basis event.

SEABROOK - UNIT 1 B 3/4 7-3 Amendment No.

-PLANT-SYSTEMS

BASES-3/4.7.6 CONTROL ROOM EMERGENCY MAKEUP AIR AND FILTRATION SUBSYSTEM The OPERABILITY of the Control Room Emergency Makeup Air and Filtration Subsystem ensures-that: (1) the allowable temperature for continuous-duty rating for.the equipment and instrumentation cooled by this system is not -

exceeded; and -(2) the control < room will-remain habitable for operations personnel during and following credible accident conditions. Cumulative operation of the system with the heaters on for 10 hours1.157407e-4 days <br />0.00278 hours <br />1.653439e-5 weeks <br />3.805e-6 months <br /> over a 31-day period

• is sufficient to reduce the buildup of. moisture on.the adsorbers and HEPA filters. Heaters run continuously to maintain the relative humidity- below 70%.

The OPERABILITY of this system in conjunction with control room design provisions is_ based on limiting the radiation exposure to personnel occupying-the control room to 5 rems or less whole body, or its equivalent. This limitation is consistent with the requirements of General Design Criterion 19 of Appendix A,10 CFR Part 50. ANSI N510-1980 will be used as a procedural guide for surveillance testing.

3/4.7.7 SNUBBERS All snubbers are required OPERABLE to ensure that the structural inttgrity of the Reactor Coolant System and all other safety-related systems is maintained during and_following a seismic or other event initiating dynamic loads.

Snubbers are classified and grouped by design and manufacturer but not by-size. For example, mechanical snubbers utilizing the same design features of the 2-kip,10-kip and 100-kip capacity uanufactured by Company "A" are of the same type. The -same design mechanical snubbers manufactured by Company "B" for the purposes 'of this Technical Specification would be of a different type, as would hydraulic snubbers from either manufacturer.

-A list of individual snubbers with detailed information of snubber location and size and of system affected shall be available at the plant in accordance with Section 50.71(c) of 10 CFR Part 50. The accessibility of each- -

snubber shall- be determined and approved by the Station Operation Review Committee (SORC). The determination shall be based upon the existing radiation

. levels and.the expected time to perform a visual inspection -in each . snubber location as well as other factors associated with accessibility during plant operations (e.g., temperature, atmosphere, location, etc.), and the recommendations of Regulatory Guides 8.8 and 8.10. The addition _ or_ deletion of i any hydraulic or mechanical snubber shall- be made in accordance with Section

-50.59 of 10 CFR Part 50.

Surveillance to demonstrate OPERABILITY .is by performance of the require-ments of an approved inservice inspection-program.

Permanent or other exemptions from the_ surveillance program for individual snubbers may. be granted by the Commission if_ a just_ifiable basis for.

exemption is presented and, if applicable, snubber life destructive testing was performed to qualify the snubbers for the applicable design conditions at-either the completion of their fabrication or at a .,ubsequent-date. Snubbers so exempted shall be listed in the list of individual snubbers indicating the extent of the exemptions.

SEABROOK - UNIT 1 B 3/4_7-4 Amendment No.

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PLANT SYSTEMS BASES 3/4.7.7 SNUBBERS (Continued)

The service life of a snubber is established via manufacturer input and inf ormation through consideration of the snubber service conditions and associated installation and maintenance records (newly installed snubbers, seal replaced, spring replaced, in high radiation area, in high temperature area, etc.). The requirement to monitor the snubber service life is included to ensure that the snubbers periodically undergo a performance evaluation in wi ~

of their age and operating conditions. These records will provide statistical bases for future ccnsideration of snubber service life.

3/4.7.8_ SEALED SOURCE CONTAMINATION The limitations on removable contamination for sources requiring leak testing, including alpha emitters, is based on 10 CFR 70.39(a)(3) limits for plutonium. 1his limitation will ensure that leakage from Byproduct, Source, and Special Nuclear Material sources will not exceed allowable intake valucs. j

' i Sealed sources are classified into three groups according to their use, with Surveillance Requirements commensurate with the probability of damage to a source in that group. lhose sources which are frequently handled are required to be tested more of ten than those which are not. Sealed sources which are continuously enclosed within a shielded mechanism (i.e., sealed sources within radiation monitoring or boron measuring devices) are considered to be stored and need not be tested unless they are removed from the shielded mechanism, 1/4.7.9 (This se cification number is not used.)

3/4.7.10 AREA TEMPERATURE MONITORING The area temperature limitations ensure that safety-related equipment will not be subjected to temperatures in excess of their environmental qualification temperatures. Exposure to excessive temperatures may degrade equipment and can crise a loss of its OPERABILITY. The temperature limits include an allowance for instrument error of i 4.5'F.

SEABROOK UNIT 1 B 3/4 7-5 Amendment No.

1

I V, . Safety Evnluatien of I.icense Amendment Heuurst 9213 Proposed Chances.

The cooling tower functions as the backup ultimate heat sink, and is capable of cooliug the service water system heat loads following a seismic event that results in 'the collapse and greater than 95% blockage of the circulating water system tunnels. The design basis for the cooling tower assumes that the seismic event which results in the collapse of the ocean tunnels also initiates a Loss of Coolant Accident (LOCA) and a Loss of Offsite Power (l.Op). The design basis heat load for the tower therefore consists of the residual heat removal (RilR) system heat rejection, containment building spray (CilS) system heat rejcction, diesel generator cooling system heat rejection, the cooling tower pumps, and other small loads imposed on the primary component cooling water (PCCW) system during the accident.

During the initial stage of the LOCA the Emergency Core Cooling System (ECCS) operates in the injection phase, in this phase, the water supply for the ECCS pumps is the Refueling Water Storage Tank (RWST) and the heat loads imposed on the cooling tower by the ECCS-equipment is minimal. The majority of the heat load on the cooling tower occurs following switchover from the ECCS injection phase to the reciscalation phase. During the recirculation phase, valves are aligned to draw water from the containment recirculation sump to be re-injected into the reactor vessel and containment building. This water, which had previously been cool water from the RWST, now must be cooled in the RllR and-CliS ,

heat exchangers, prior to re injection. This heat is ultimately rejected to the cooling tower and when this occurs, a significant heat load is imposed on the cooling tower.

The bulk temperature of the cooling tower basin water is currently limited to an inidal temperature of 67.3*F by Technical Specification 3.7.5. -This limit was chosen to ensere that

, the cooling tower basin temperature would be limited during the design basis event to ensure that the design limitations of the primary component water cooling system are not exceeded.

An analysis has been performed by, North Atlantic Energy Service Corporation (North Atlantic), which demonstrates that the cooling tower basin average temperature conhi be allowed to increase to 80*F during a single train post LOCA cooldown, or to 87'F during a two train couldown, prior to initiating sprays and fans without exceeding equipment limitations. North Atlantic has proposed, on the basis of this analysis, that the cooling tower Technical Specification basin temperature limit be increased to 70*F. The analysis _which demonstrates this is available for NRC review at Seabrook Station. This proposed change will alleviate a significant operational burden by minimizing the potential for requiring cooling tower operation, with spray, to reduce basin temperature below the current Technical Specification value (67.3*F), during the summer months. The proposed increase .in basin temperature will maintain an adequate amount of time for operator action to initiate spray s

and fan operation and will not adversely affect the ability to remove the LOCA heat load..

If the cooling tower is manually operated, assuming maximum UCCS flows and the minimum allowable RWST level, i.e. minimizing the time to recirculation, and with the increased ba in temperature, a minimum of 74 minutes will be avai_lable for operator action to initiat_e cooling -

tower sprays and fans prior to reaching either basin limiting temperature. This time is -

greater than- the 20 minute minimum operator response time specified in NUREG 0800.

NUREG 0800 Section 6.3 states in part that where mar ual action is used, a sufficient time (greater than 20 minutes) be available for the operator to respord. Manual operation of the cooling tower will continue to allow the cooling tower to meet its design requuements and

c i .

will enhance the safe operation of Seabrook Station by ensuring that the cooling tower is operated in an ice free condition.

Although-the post LOCA cooldown is the design basis case for the cooling tower, a normal cooldown has also been evaluated with respect to the increased basin initial temperature and manual cooling tower spray and fan peration. The normal cooldown differs from the post-LOCA cooldown in that the initial heat load to the cooling tower is higher in the normal couldown case. This higher load is associated with the normal plant heat loads. These normal plant heat loads would be isolated in the post-LOCA cooldown case.

As -in the post-LOCA cooldown case, the cooling tower basin is assumed to be at its maximum initial temperature and minimum volume. The tower basin temperature is again limited to a maximum temperature of 80'F prior to initiating cooling tower spray and fan speration. This 80*F limit is conservative for this case as it is based on the larger heat loads experienced in the post LOCA cooldown case. With the maximum normal' cooldown heat load, and assuming a loss of offsite power which adds the heat rejection from both diesel generators, greater than 106 minutes is available- for operator action to start the cooling tower spr ys and fans prior to reaching a cooling tower basin average temperature of 80'F.

There is adequate procedural guidance, operator training, and main control room indication available, to alert the operator to the 'nced to initiate cooling tower fan and spray operation.

During the postulated design basis scenario, operators are directed to monitor cooling tower performance at step 10 of Seabrook Station eme' mncy operating procedure E-0, " Reactor Trip or Safety injection" This step directs the operator te verify ultimate heat sink 5

operation if the cooling towcr is the ultimate heat sink the operator is d'rected to initiate cooling tower spray and/or fan operation based on the combination of wet. bulb temperature ano ;( CW heat exchanger outlet temperature. If the criteria to initiate cooling tower spray and fan operation has not been reached when step 10 of emergency operating procedure E-0 is reached, operators will periodically monitor cooling tower operation to ascertain the need for spray and fan operation. In addition, there are PCCW high temperature alarms on the main control board, which will alert operators to the need to initiate cooling tower spray and fan operation. ~

If a Tower Actuation were to occur without an accompanying entry into the Emergency Operating Procedures; Abnormal Procedure OS1216.01, " Degraded Ultimate Heat Sink" provides guidance on cooling tower fan and spray operation.

Operator training is conducted using abnormal and emergency simulator scenarios. Several of these scenarios emphasize monitoring ultimate heat sink performance. These training scenarios verify that appropriate operator action is taken during a cooling tower actuation occurring with and without entry into emergency operating procedure E-0, " Reactor Trip or Safety Injection".

The cooling tower spray bypass valves,1-SW-Vt39 - and 1-SW-V140, are included in the Inservice Test program and are periodically surveilled pursuant to Technical Specification

- Surveillance Requirement 4.0.5. Ybis requirement demonstrates that the' valves will operate

-as required by performing valve stroke times and remote position indication verification.

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s

.e Based upon 'the above, there_ is sufficient time and procedural' guidance available to manually-_

initiate cooling tower spray and fan operation'following the cooling tower _ design basis event.

In ' addition, operators are periodically trained to initiate appropriate action regarding manual cooling tower operation. There is also alarm indication available in the main control room, to alert and direct operators to initiate coaling tower fan and spray operation. Theefore, operation of _the cooling tower with the sprays and fans manually controlled ~ and with an_ _

n increased cooling tower basin-Technical Specification temperature limit,'does not require immediate operator action to mitigate the effects of an accident,_and therefore the proposed Technical Specification change does not create a safety concern.

In conclusion, the proposed changes will allow cooling towc: spray and fan operation.to be ,

manually initiated by the operator. as opposed to automatically occurring during a cooling -

tower actuation and will reduce the times that the cooling tower must be operated to reduce basin temperature. This change is necessary to prevent icing cf the cooling tower:during-cooling tower operation when ambient temperature is- below freezing and ;will enhance the safe operation of the plant. The surveillance-requirements will continue to verify that the cooling tower is OPERABLE and capable of performing its design function as the alternate -

Ultimate lleat Sink. As discussed above, sufficient time is -available' for the operators to manually initiate cooling tower spray and fan operation even with the increased basin temperature. Therefore, there is no significant i crease in the safety consequences associated with the requested amendnient.

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V. Deter mination of Nignif'icnnt fininrds for I.lcense Amendment Hrquest 9213 proposd_

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1. The proposed changes do not ins oh t a significant increase it the probability or consequences of an accident presiously evaluated.

Verification of the proper actuation of the automatic valves in the flowpath is currently performed during cooling tower surveillance testing; the addition of a Technical Specification suiveillance requirement to perform this verification has no affect on the operation of the plant. This change affects only the operating mode for the cooling tow, r fans and the initial basin temperature. Chapter 9, Section 9.2.5.2 of the Updated Final Safety Anaiv -s lleport (UFSAlt) recog*cs the manual operating mode of the cooling tower fans anc sprays by stating that greater than 30 minutes is availabic, following the design basis event, in which to initiate f an and/or spray operation. It has been Jeterminc I by North Atlantic that at least 74 minutes will be available to the operators in which to take manual action and initiate cooling tower fan anJ spray operation. This time meludes the consideration of the increase in the initial cooling tower basin temperature. This is an acceptabl amount of time in which to initiate manual action and is greater than the 20 minute minirnum specified in N U Rl:0 okuu. ~! her efo - the probability of an accident previously evaluated in the UI SAR is not significantly in< acd by the pioposed revision.

I he cooling towei is automatically aligned as the ultimate heat sink following a scismic esent which icsults in the blockage of the circulating water tunnels and subsemient loss ^ Service Water (SW) sptem pressure. Manual control of the cooling tow e w hile retaining the automatit switchover to the tower, will not adversely affect the ability of the cooling tower to function in this capacity. As discussed abo"e, with the increased initial basin temperature, sufficient time exists for the inanual initiation of cooling tower sprays and fans following the seismically imiuced 1.oss Of Coolant Accident (l.OCA). Additionally, there is adequate procedural guidance, operator training and alarm indications to alert and direct operators to initiate cooling tower fan and spray operation.

With the ultimate heat sink available, all saf ety systems will function as design:d. ~1 his _

change will therciore have ao adverse affect on the doses to members of the public from any previously analynd accident and therefore the consequences of an accident pr eviously  ;

evaluated in the UI'S AR is wt significantly increased by the proposed revi3ico.

2. The proposed changes do not create the possibility of a new or different Lind of accident f rom any acci4nt presiously evaluated.

The propo.ed change modifies the cooling tower operating mode from automatic actuation to manual actuation. This not a new mode of operationi this mode of operation is presently acknowledged and described in UFSAR Chapter 9 Manual control of the cooling tower will not aaversely af fect the availability of the cooling tower or its heat removal capability. Tht cooling towe, spray bypass vah es,1 SW V139 and 1 SW-V140, are included in the Insettic; Test pogram and are periodically surveilled pursuant to Technical Specification Surveillance R e quii c me nt 4.0.5. This requirement demonstrates that the valves will operate as required by performing salve stroke times and remote position indication verification. No credible 12 i

1

i failure mechanis n is created by manual control of the cooling tower which could result in the initiath.a of an accident. Tbc 70*F initial basin temperature allows sufficient time for operator action to initiate cooling tower fan and spray operation in accordance with prt e d u res. Therefore, the possibility of a new or different kind of accident from any accident previously evaluated in the UFSAR is not created.

3. The proposed changes do not result in a significant reduction in the margin of safety.

The llases for Technical Specification 3/4.7.5 state that the OPERAlllLITY of the cooling -

tower ensures that sufficient cooling capability is available to provide normal cooldown of the facility or to mitigate the affects of accl6e t conditions within acceptable limits. The ,

proposed change modifies the operation of the coohng tower sprays and fans from automatic to manual initiation. Manual operation of the cooling tower sprays and fans will not adversely affect cooling tower operation or its heat removal capability and the cooling tower will still be verified to be OPERABLE. An OPERAHLE Cooling Tower ensures that 'he assumptions in the 11ases of Technical Specifications are not aficcied and ensures tha. he nargin of safety is not reduced.

, The design basis cvent for the cool.nt. tower a seismic event which collapses the circulating water system tunnels. The design ba . assumes that the 'smic event which collapsed the tunnels, also caused a Loss of Coolant Accident and Los. of Offsite Power.

In this limiting scenario, greater than 74 minutes are available to initiate cooling tower sprays and fans following the seismic event. Adequate procedural guidance, operator '

training, and alarm indications are provided to facilitate operation of the f ans and sprays.

' lowing this manual action, the full capability of the cooling tower ultimate heat sink is availat le to meet the requirements of the design basis event. The 70'F initial basin  ;

temperature allows sufficient time for operator action to manually initiate cooling tower fans and sprays in accordance with procedures.

Therefore, the assua.rment, in the Bases of Technical Specifications are not affected and this change will not result in a signill nt reduction in the margin of safety.

i 13 4

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VI. I'roposed Schedule for 1,1 cense Amendment issuance nr4 I ffectiveness North Atlantic requests NRC review of License Amendment Request 9213 and issuan.e of a license amendment having immediate effectiseness by March 31, 1993 or as soon as possible.

The Technical Specification changes proposed herein will enhance the safe operation of the plant by precluding the possibility of damage to the cooling tower or fans due to ice buildup.

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Yll. _l:nvironinen[pl Impart Aueuinent North Atlantic has reviewed the proposed license amendment against the criteria of 10CFil51.22 for environmental consider -tions. The proposed changes da not involve a significant harards consideration, nor increase the types and amounts of effluent that may be released offsite, nor tignificantly increase individual or cumulative occ upational radiation exposures. Ilused on the fo r e gnin g, North Atlantic concludes that the proposed change rucett, the crit:ria delineated in 10CFit51.22(c)(9) for a categorical exclusion from the requirements fur an I!nvironruental Impact Statement.

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. i ATTAC;; MENT C COOLING _ TOWER FAN AND SPRAW OPERATION J i

77'F ,_

FANS - 0FF FANS - ON SPRAY - ON SPRAY - ON 60'F -

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to increase (temp.)

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