ML20127H194

Proposed TS 3/4.7.2 Re Control Room Emergency Ventilation Sys & TS Table 3.3.5.5-1, Control Bldg Emergency Ventilation Sys Instrumentation

ML20127H194
Person / Time
Site:	Brunswick
Issue date:	01/12/1993
From:	CAROLINA POWER & LIGHT CO.
To:
Shared Package
ML20127H191	List: ML20127H187 ML20127H194
References
TAC-M85143, TAC-M85144, NUDOCS 9301220249
Download: ML20127H194 (18)

Text

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ENCLOSURE 4 I BRUNSWICK STEAM ELECTRIC PLANT, UNITS 1 AND 2 NRC DOCKET NOS. 50 325 & 50 324 OPERATING LICENSE NOS. DPR 71 & OPR 02 REQUEST FOR LICENSE AMENDMENT CONTROL DUILDING EMERGENCY AIR flLTRATION SYSTEM (NRC TAC NOS. M85143 AND M85144)

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PLANT SYSTFHS 3/4.7.2 EQUIROL RDOM EMERGENCY VENTILATION SYSTEM LIMITING CONDITION FOR OPERATION 3.7.2 The Control Room Emergency Ventilation System shall be OPERABLE with:

a. An OPERABLE Rad!3 tion (Smoko) Protection Mode consisting of two OPERABLE control room en.ergency filtration subsystems.

b. An OPERABLE Chlorine Protection Mode.

ITPldIADILITY: OPERATIONAL CONDITIONS 1, 2, 3, 4, 5, *, and **

bCTION:

a. In OPERATIONAL CONDITIONS 1 and 2:

1. With one control room emergency filtration unit inoperable, restore the inoperable control room emergency filtration unit to OPERABLE status within 7 days or be in at least HOT SHUTDOWN within the next 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and in COLD SHUTDOWN within the following 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

2. With both control room emergency filtration units inoperable, be in 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 in COLD SHUTDOWN within the following 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

b. In OPERATIONAL CONDITION 3:

1. With one control room en.orgency filtration unit inoperable, restore the inoperable control room emergency filtration unit to OPERABLE status within 7 days or be in COLD SHUTDOWN within the following 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

2. With both control room emergency filtration units inoperable, be in COLD SHUTDOWN within the following 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />,

c. In OPERATIONAL CONDITIONS 4, 5, and *:

1. With one control room emergency filtration unit inoperable, restore the inoperable control room emergency filtration unit to OPERABLE status within 7 days or initiate and maintain operation of the remaining OPERABLE control building emergency filtration unit in the Radiation Protection Mode.

2. With both centrol room emergency filtration units inoperable, suspend all operations involving CORE ALTERATIONS, handling of irradiated fuel in secondary containment, and operations with a potential for draining the reactor vessel.

• During movement of irradiated fuel assemblies in the secondary containment.

• • The chlorine Protection Mode is required to be OPERABLE at all times when the chlorine tank car is within the exclusion area.

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PLANT SYSTIME l 3/4.7.2 CONTROL ROOH EMERGENCY VENTILATION SYSTEM LIMITING CONDITION FOR OPERATION (Continued) _

ACTION (Continued):

d. With the Chlorine Protection Mode inoperable, within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> remove the chlorine tank car from the exclusion area. If the tank car physically can not be removed from the exclusiot; area, take the ACTIONS required in items a.2, b.2, and c.2 above.

SURVEILLANCE REQUIREMENTS 4.7.2 The control building emergency ventilation system shall be demonstrated OPERABLE:

a. At least once per 31 days by initiating flow, from the control room, through the HEPA filter and charcoal adsorbers in each filtration unit and verifying that the system operates for at least 15 minutes.

b. At least once per 18 months or (1) after any atructural maintenance on the HEPA filter or charcoal adsorber housings, or (2) following painting, fire, or chemical release in any ventilation zone communicating with the system by:

1. Verifying that the cleanup system satisfies the in-place testing acceptance criteria of h 99 percent efficioney using l the test procedure: of Regulatory Positions C.S.a, C.5.c, j

and C.S.d of Regulatory Guide 1.52, Revision 1, July 1976, and the system' flow rate is 2000 cfm i 10 percent.

2. Verifying within 31 days after removal that a laboratory analysis of a representative carbon sample obtained in accordance.with Regulatory Position C.6.b of Regulatory Guide 1.52, Revision 1, July 1976, meets the laboratory . .

testing criteria of Regulatory Position C.6.a of Regulatory Guide 1.52, Revision 1, July 1976.

3. Verifying a system flow rate of 2000 cfm i 10% during system operation when tested in accordance with ANSI N510-1975.

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c. After every 720 hours0.00833 days <br />0.2 hours <br />0.00119 weeks <br />2.7396e-4 months <br /> of charcoal adsorber operation by verifying within 31 days after removal that a laboratory analysis of-a representative carbon sample obtained in accordance with Regulatory Position C.6.b-of Regulatory Guide 1.52, Revision 1, July 1976 meets the laboratory testing criteria of Regulatory Position C.6.a of Regulatory Guide 1.52, Revision 1, July 1976.

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PLANT SYSTEMS SURVEILLANCE REQUIREMENTS (Continued)

d. At least once per 18 months bys

1. Verifying that the pressure drop across the combined HEPA filters and charcoal adoorber banks is $ 5.25 inches water gauge while operating the filter train at a flow rate of 2000 cfm i 10%.

2. Verifying that on a smoke detector or control room ventilation system high radiation test signal,.the control building ventilation system automatically diverts its inlet flow through the HEPA filters and charcoal adsorber banks of the emergency filtration system.

3. Verifying that on a simulated chlorir.e isolation signal, the control buildir.g ventilation system automatically isolates, and the control room emergency flitration system cannot be started by a smoke detec?or or control room ventilation system high radiation test signal.

4 Verifying that the system maintains the control room at a positive pressure relative to the outside atmosphere during system operation.

e. After each completo or partial replacement of a HEPA filter bank by verifying that the HEPA filter banks remove 2 99% of the DOP when tested in-place in accordance with ANSI N510-1975 while operating the purge system at a flow rate of 2,000 cfm i 10%.

f. After each complete or partial replacement of a charcoal adsorber bank by verifying that the charcoal adsorbers remove 2 99% of a halogenated hydrocarbon refrigerant test gas when tested in-place in accordance with ANSI ~N510-1975 while operating the purge system at a flow rate of 2,000 cfm i 10%.

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PLANT SYSIKH3 I!MiXE jl11.,2 CONTROL BUILDING EMER91NCY VENTILATION SYSTFji Dackaround One of the principal design objectives of the Control Building Heating, Ventilation and Air conditioning (CBHVAC) System is to termit continuous occupancy et the Control Room Emergency Zone under normal operating conditions and under the postulated design basis events throughout the life of the plant.

The Control Building HVAc System must function to provide protection to the operators for three type events: a radiation event, up to and including a Design Basis Accident (e.g., Main Steam Line Break (HSLB) Accident, Refueling Accident, control Rod Drop Accident, or Loss of Coolant Accident (LOCA]), a toxic gas event (complete rupture of the $5 ton chlorine tank car located near the Service Water Building, or a slow leak lasting for an extended period of time), and an external smoke event. These events form the basis for the design of the control Building Emergency Ventilation (CBEVS) function of the C8HVAC dystem. ,

i The CBEVS is designed to meet General Design Criteria-(GDC) 19 (Reference 1).

In addition, the system is designed using the guidance of Regulatory Guide 1.95, Revision 1 (Reference 2). Commitments have also bees made to design the emergency air filtration function of the CBHVAC Syst(m te meet the single failure criteria described in IEEE 279-1971 (Reference- 3, Section 9.4.1.3.c), with exceptions noted in the control Room Habitability Analysts, Revision 2 (Reference 4).

1&G Operability of the CBEVS ensures that the control room will remain habitaale ,

for operations personnel during and following all credible hazard event  !

scenarios external to the control room, consistent with the aneumptions in the various analyses. Two redundant subsystems of the CBEVS are required to be OPERABLE to ensure that at least one is available, assuming a single failute disables the other subsystem. The CBEVS is considered OPERABLE when the individual components necessary to control operator e*paanre are operable in /

both subsystems. For the Radiation Protection hode, a subsystem is considered j) - OPERABLE when its associated

1. Fan in OPERABLE,

2. HEPA filter and charcoal adsorbers are not excessively restricting flow and are capable of performing their filtration functions, and

3. Ductwork and dampers are OPERABLE, and air circulation can be maintained as required in Reference 12, Section 3.1.

For the chlorine Protection Mode, a subsyntem is considered OPERABLE whent b

1. The isolation dampers are OPERABLE, and

2. The logic componente necessary to achieve automatic isolation are.

functional, as described in Reference 12, Section 3.li Two-additional OPERABIb1TY requiremehts apply to all modes of CBEVS operation.

The CBHVAC Control- Air System must be OPERABLE to support damper operation.

In addition, the Control Room Envelope must be maintained, including the integrity af the walls, floors, ceilings, ductwork, and access doors. The Control Room Envelope includes the electronic equipment rooms, the central

- control room area, computer. rooms, kitchen, restrooms, and the supply and return ductwork up to and including the isolation dampers. ,

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The fo11owir.9 components, including their associated logic trains, actuation  ;

devices, and power supplies, are non-redundant. 'Their OPERABILITY affects i both trains of the CBEVS. These components ares control room (washroom)~

exhaust isolation damper, control room nonna) make-up damper, and the control room emergency recirculation damper. In addition, the Brunswick control room-is not equipped with redundant outdoor air intakes (References 4 and 5).

The Radiation Protection Mode of operation protects the control room operators from those events which may result in the release of radioactivity. The Radiation Protection Mode of operation also provides protection to the control room operators in the event of an external smoke event.

During a radiation event, the CBHVAC System is required to automatically

• isolate and enter the Radiation Protection Mode on a Control Room Intake High l Radiation signal from the Area Radiation Honitoring system. Upon receipt of a high radiation signal, the CDHVAC System is automatically realigned to the emergency mode of operation. The normal fresh air inlet closes, and, at approximately the same time, the emergency air filtration unite begin operation, recirculating control room air and providing filtered makeup air to minimize contamination build-up and provide Iositive pressure in the control Room Envelope. The CBHVAC System responds to an external emoke event in the same manner as it does for a radiation event.

In the event of a chlorine release, the CBEVS enters a full recirculation mode (Chlorine Protection Mode), with no outdoor air intake. The emergency flitration trains do not start, since they do not effectively remove chlorine and may be damaged by the presence of chlorine. Protection for chlorine gas events " overrides" any concurrent, ongoing, or subsequent radiation or smoke initistion signals. The oveeride design offers protection to operations personnel in the Control Room by providing protection against potentially latal chlorine gas releases. This protection is required any time the chlorine tank car is within the exclusion area.

Apolicability The OPERATIONAL CONDITION applicabiliti6s ensure that the system is capable of performing these functions eben the potential for radiation releases and external smoke hazards exir'. c In OPEkAT10NAL CONDITIONS 1, 2, and 3, the system must be OPERABLE to control operator exposure during and following a design basis accident, since the accident could Icad to a fission product release.

In ^PERATIONAL CONDITIONS 4 and 5, the probability and consequences of a derign basis accident are reduced because of the pressure and temperature limitations in theme OPERATIONAL CONDITIONS. Maintaining the CBEVS ODERABLE is not rtquired in OPERATIONAL CONDITIONS 4 and 5, except for the following sit aattons under which significant radiological releases can be postulated:

1. During movement of irradiated ' si assemblies in the secondary containment,

[ 2. During CORE ALTERATIONS, and 3

3. During opera: ions with a potential for draining the reactor vessel.

Requiring OIERADILITY of the Radiation Protection Mode of the CBEVS during OPERATIONAL CONDITIONS 4 and 5 ensures that th7 oystem is available during the above ovolutioni, v1Mh th9 exception the movement of irradiated fuel in secondary contairaent; tv refnre, a specific applicability OPERATIONAL-CONDITION nan been added for this activity.

Operability -af the chlorine Prot o nion Mode of _ the C3EVS is required any time the chlorine tank car is within the exclusion area.- Analyses demonstrate that

. movement:of the tank car outside f.he exclusion area sufficiently reduces the

threat of control room operator incapacitation from a release of this chemical.

Action ai With one emergency filtration subsystem inoperable, the inoperabis subsystem

, must be restored to OPERABLE status sithin 7 days. With the unit in this condition, the remaining subsystem is adequate to perform con:rol room radiation prntsetion. The loss of a sing,'e emergency filtration unit means that the CBEvs reliability is reduced because a single failure in the OPERABLE subsystem could result in reduced or lost system capability. The 7 day out of service time is based on the low probability of a design basis accident and a singlu failure in the OPERABLE subsystem occurring during this time period, and the capability of the remaining subsystem to provide the required capabilities.

During OPERATIONAL CONDITIONS 1 and 2, the plant must be placed in an OPERATIONAL CONDITIDF that minimites risk if the inoparable suboystem cannot be restored to OPERABLE status within the required 7 days. To achieve this status, the plant must be placed in HOT SHUTDOUN within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and COLD SHUTDOWN within the following 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. These allowed completion times are reaconable, based en operating experience, to allow the plant to reach these OPERATIONAL CONDITIONS f rom Jull power operation jn an orderly manner and without unnecessarily challenging plant systems.

The lous of both emergency filtration subsystems means that the radiation protection function is lost. The plaht must be plat:ed in er OPERATIONAL CONDITION that minimites risk. To achieve this status, the plant must be placed in HOT SHUTDOWN within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and COLD SHUTDOWN within the following 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. These allowed completion times are reasonible, based on operating experience, to allow the plant to reach these OPERATIONAL CONDITIONS from f ull power operation in an orderly manner and without unnecessarily challenging plant systems.

Action b.

With one emergency filtration subsystem inoperable, the inoperablu suboystem must be restoted to OPERABLE status within 7 dayn. With the unit in thin condition, the remaining subsystem is adequate to perform control room radiation protection. The loss of a single emergency filtration unit maaro that the CBEVS reliability is reduced because a single f ailure in the OPERABLE subsystem could result in reduced or lost system capability. The 7 day out of service Line is based on the low probability of a design basis accident and a single failure in the OPERABLE subsystem occurring during this time period, and the capability of the remaining subsystem to provide the required capabilities.

During OPERATIONAL CONDITION 3, the plant must be placed in an OPERATIONAL CONDITION that minimites risk if the inoperable subsystem cannot be restored to OPERABLE status within the required 7 days. To achieve this status, the plart must be placed in COLD SHUTDOWN within the following 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. The allowed completion time is reasonable, based on operating experience, to allow the plant to reach thle OPERATIONAL CONDITION from HOT SHUTDOWN in an orderly nanner and without unnecessarily challenging plant systems.

The loss of both emergency filtration subsystems means that the radiation protection function io lost. Thu plant must be placed in an OPERATIONAL CONDITION that minimites risk. To achieve this rtatus, the plant must be placed in COLD SHUTDOWN within the following 24 houro. The allowed completion time is reasonable, based on operating experienco, to allow the plant to reach this OPERATIONAL CONDITION frou HOT SHUTDOWN in an orderly manner and without unnecessarily challenging plant systems.

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httipn er With one emergency filtration subsystem inoperable, the inoperable subsystem must be restored to OPERABLE status within 7 days. With the unit in any of these conditions, the remaining subsystem is adequate to perform control room radiation protectian. The loss of a single emergency filtration unit means that the CBEVs reliability is reduced because a single failure in the OPERABLE subsfetem could result in reduced or lost system capability. The 7 day out of service time is based on the low probability of a design basis accident and a single f ailure in the OPERABf.E subsystem occurring during this time period, and the capability of the remaining subsystem to provide the required capabilities.

During OPERATIONAL CONDITIONS 4, 5, and while irradiated fuel is being moved in secondary containment, if the inoperable emergency filtration subsystem cannot be restnrad to OPERABLE status within 7 days, tne remaining OPERABLE subsystem may be placed in the Radiation Protection Mode. This action ensures that the remaining subsystem is OPERABLE, that no failures which could prevent automatic actuation will occur. This action also ensuras that any active failure would be readily detected.

An alternativs to placing the remaining subsystem in service is to immediately suspend activities that present a potential for releasing radioactivity that might require operation of the CBEVS. This alternative places the unit in a condition that minimir.es risk.

betion_dx With the chlorine Protection Mode inoperable, the chlorine tank car must be removed from the exclusion area within the next eight (8) hours to ensure ,

adequate protection for the operators. Chlorine gas protection is not required with the tank car outside of the exclusion area. Eight hours is cons!dered adequate time to perform the necessary system alignments and to allow plant personnel to remove the chlorine tank car from the site in an orderly manner.

With the plant physically unable to remove the chlorine tank car from the site, as required by this statement, ACTION d. requires the plant to take actions to place the plant in a condition that minimites risk of core damage or other types of radiological release events.

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Surveillance Reauirements The SURVEILLANCE REQUIREMENTS (SR)-in this specification verify that a subsystem in the standby mode starts on demand and continues tu operate.

Standby systems are checked periodically to ensure that the automatic start function is consistent with the assumptions in the Control Room Habitability Analyses (References 4 and 6). Since the environmental conditions on this system are not oevere, monthly demonstration of the capability of the system to operate by SR 4.7.2.a is considered adequate. The 215 minute run time is considered adequate for operation of systems without heaters (Reference 16).

SR 4.7.2.b verifies the capability of the filtration system at least once every 18 months, or 1) following any structural maintenance on the filtration unit HEPA filter or charcoal adoorbers or following painting, fire, or chemical release in any ventilation zone communication with the system.

Testing is performed in accordance with applicable sections of Regulatory Guide 1.52, Revision 1, and ANSI N510-1975. Acceptance criteria provides-assurance that the efficiency used in the control Room dose analyses is conservative. This is consistent with the guidance provided in GL 83-13 (Reference 7).

SR 4.7,2.c verifies adequacy of the charcoal filtration system following every 720 hours0.00833 days <br />0.2 hours <br />0.00119 weeks <br />2.7396e-4 months <br /> of operation. The time of operation is based on the recommendations of Regulatory Guide 1.52, Revision 1 (Reference 8), and early nuclear plant

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filter testing (Reference 10). j SR 4.7.2.d demonstrates functional capability of the ayatem by verifying

1) proscure drop across the HEPA and charcoal filtration units, 2) automatic j emergency system initiation upon receipt of a smoke detector or high radiation test signal, 3) the override function of the chlorine protection function, and j

4) ability of the system to maintain a positive pressure relattve to the outside atmosphere during system operation. The maximum precsure drop of 5 5.25 inches water gauge is based on a CBEVS pressure drop analysis (Reference 9) and fan capability. This maximum presoure drop ensures the system is capabic of delivering rated flow with 1 inch water gauge margin for filter loading. TLs positive pressure test is performod to ensure that the control room is maintained positive to any potenttally contmainated external atmosphere, including the outside atmosphere and adjacent building atmosphere (s). Testing of the chlorine override function ensures operability of the chlorine protection mode of the CBEVS by demonstrating the capability of the system to prevent the emergency filtration units f rom initiating during a chlorine event.

1 SR 4.7.2.e and SR 4.7.2.f verify that the flitratir.n capability of the HEPA l and charcoal adsorber banks is consistent with that assumed in the Control '

Room Habitability Analyses (References 4 and 6) following partial or complete ,

replacement of either filtration component. The testing is performed in accordsnee with the applicable sections of ANSI N510-1975 (Reference 14).

Referenggg

1. 10 CFR 50, Appendix A, General Design Criteria 19, control Room.

2. Regulatory Guide 1.95, Revision 1, Protection of Nuclear Power Plant Control Room Operators Against an Accidental Chemical Release.

3. Updated FSAR, Brunswick Steam Electric Plant, Unita 1 F 2.

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4. NUS-3697, Revision 2, February 1983, control Room Habitability Analysis.

5. NLU-83-673, THI Action Item III.D.3.4 - Control Room Habitability, NRC-Safety Evaluation dated October 18, 1983. .,

6. NUS-4758, control Ronm Radiological Reanalysis, August, 1985.

7. Generic Latter 83-13, Clarification of Surveillance Requirements for HEPA Filters and Charcoal Adsorber Units in Standard Technical Specifications of ESF Cleanup Systems, March 2, 1983.

8. Regulatory Guide 1.52, Revision 1, July 1976, -i

9. CP&L Calculation G0077A-01, Control Room Emergency Filter System Differential Pressure Analysis.

10. Original FSAR, BSEP, Unita 1 and 2, date, Appendix K.

11. IEEE 279-1971, IEEE Critoria for Protection Systems for Nuclear Power Generatf.ng Stations.

12. DBD-37, Design Basia Document for control Building Hoating, Ventilation, and Air Conditioning System.

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13. NRC-89-103, NRC Safety Evaluation for Control Room Habitabi11ty, February 16, 1989.

14. ANSI N510-1975, Testing of Nuclear Air Cleaning Systems.

15. ANSI H509-1976, Nuclear Power Plant' Air Cleaning Units

16. NUREG-1433, Standard Technical specifications, General Electric Plants, I BWR/4, Revision 0, September 28, 1992, b

INSTRUMENIATIQH CONTROL {Ll!ILDING EMERgit[gY VENTILATION SJEIIH LIMITING CONDITION FOR OPERATION 3.3.5.5 The Control Building Emergency Ventilation System instrumentation shown in Table 3.3.5.5-1 shall be OPERABLE.

APPLICABILITY: As shown in Table 3.3.5.5-1.

ILC11.QUS

a. With one or more detectore inoperable, take the ACTION required by Table 3.3.5.5-1. __

b. The provisions of Specification 3.0.4 are not applicable.

SURVEILLANCE REQUIREMENTS 4.3.5.5 Each of the above required control building emergency ventilation instruments shall be demonstrated OPERABLE by performance of the testing at the frequency required by Table 4.3.5.5-1.

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TABLE 3.3.5.5-I .

CONTROL BUILDING EMERGENCY VENTILATION SYSTEM INSTRUMENTATION REQUIRED NUMBER APPLICABLE OF DETECTORS OPERATIONAL ALARM / TRIP CONDITIONS ACTION SETPOINT FUNCTION PER TRIP SYSTEM CHLORINE ISOLATION:

(b) 90 5 5 ppm

1. Control Building Air Intake 4 (a)

(Local) Trip System (b) 90 5 5 ppm

2. Chlorine Tank Car Area (Remote) 4 (a)

Trip System RADIATION PROTECTION:

2 1, 2, 3, 4, 5, and 91 5 7 rJt/hr (d)

1. Control Building Air Intake (c)

CONTROL ROOM ENVELOPE SMOKE PROTECTION:

3, 4, 5, and 92 NA 2 ' . , 2,

1. Zone 4 (c) 1, 2, 3, 4, 5, and 92 NA 2

2. Zone 5 (c)

(a) Four OPERABLE detectors per trip system, consisting of two detectors per trip subsystem.

(b) With the chlorine tank car within the exclusion area.

(c) During movement of irradiated fuel assemblies in the secondary containment.

(d) Allowable value of 5 10mR/hr.

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s se TABLE 3.3.5.5-1 (Continued) l CONTROL BUI1 PING EMERCENCY VENTILATION SYSTEM INSTRUMENTATION i

ACTIONS ACTION 90

a. With one chlorine detector of either or both trip subsystems of either or both tr!p nystems inoperable, restore the inoperable detec t.o r ( s ) to OPERABLE status within 7 days or, within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />, isolate the Control Room and operate in the Chlorine Isolation Mode.

b. With a trip subsystem of either trip system inoperable, within one hour isolate the Control Room and operate in the Chlorine Protection Mode.

ACTION 91

a. With one radiation detector inoperable, restore the inoperable detector to OPERABLE status within 7 days or, within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />, isolate the Control Room and operate in the Radiation Protection Mode.

b. With both radiation detectors inoperable, within one hour isolate the Control Room and operate in the Radiation Protection Mode.

ACTION 92

a. With less than two (2) ionization detectors OPERABLE in either or both zones, restore two (2) detectors within each zone to OPERABLE statun within 7 days or, within the next 6 !.ours, isolate the Control Room and operate in the Radiation (Smoke) Protection Mode. _

b. With less than one (1) ionization detector OPERABLE in either or both zones, within one hour isolate the Control Room and operate in the Radiation (Smoke) Protection Mode.

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TABLE 4.3.5.5-1 CONTROL BUILDING EMERGENCY VENTILATION SYSTEM INSTRUMENTATION SURVEILLANCE REOUIREMENTS CHANNEL CHANNEL FUNCTIONAL CHANNEL FUNCTION CHECK TEST CALIBRATION CHLOUNE ISOLATION:

1. Local Detection NA M A' Trip System

2. -Remote Detection NA M A Trip System RADIATION PROTECTION:

1. Control Building D M R Air Intake CONTROL ROOM ENVELOPE SMOKE PROTECTION:

1. Zone 4 NA 6 months (a)

2. Zone 5 NA 6 months (a)

(a) See Surveillance Requirement 4.7.2.d.2

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• i INSTRUMENTATION  ?

EMId 3/4.3.5.5 CONTROL BUILDING EMERGENCY VENTILATION SYSTEM Backoround One of the principal design objectives of the control Building Heating,-

Ventilation and Air Conditioning (CBHVAC) System is to permit continuous occupancy of the Control Room Emergency Zone under normal operating conditions and under the pottulated design basis events throughout the life of the plant.

The Control Building HVAC System must function to provide protection to the operators for three type events: a radiation event, up to and-including a Design Basis Accident (e.g., Main Steam Line Break (MSLB) Accident, Refueling Accident, Control Rod Drop Accident, or Loss of Coolant Accident (LOCA)), a toxic gas event (complete rupture of the 55 ton chlorine tank car located near the Service Water Building, or a slow leak lasting for an extended period of time), and an external smoke event. These events form the basis for the design of the Cantrol Building Emergency Ventilation (CBEVS) function of the CBHVAC System.

During a radiation ever.t, the CBHVAC System is required to automatically isolate and enter the Radiation Protection Mode on a Control Room Intake High Radiation sign.nl from the Area Radiation Monitoring System. Upon receipt of a=

high radiation signal, the CBHVAC System is automatically realigned to the emergency mode of operation. The normal fresh air inlet closes, and, at approximately the same time, the emergency air filtration units begin operation, recirculating control room air and providing filtered makeup air to minimize contaminated build-up and provide positive pressure in the Control Room Envelope. The CBHVAC System responds to an external smoke event in the same manner as it does for a radiation event.

In the event of a chlorine release, the CBHVAC System enters a full recirculation mode, with no outdoor air intake. The amergency-filtration trains do not start, since they do not effectively remove chlorine-and may be damaged by the presence of chlorine. Protection for chlorine gas events

" overrides" any concurrent, ongoing, and any subsequent radiation or smoke initiation signals. The override design offers protection to-operations personnel in the Control Room.for the most immediate life-threatening event by providing protection against potentially fatal chlorine gas releases. This-protection is required any time the chlorine tank car is within the exclusion area.

The CBEVS is designed to meet the criteria of General Design Criteria (GDC) 19 (Reference 1). In addition, the system has beer, designed using'the guidance-of Regulatory Guide 1.95, Revision.1 (Reference 2). Commitmento have also been made to design the CBEVS to meet the single failure criteria described in IEEE 279-1971 (Reference 3, Section 9.4.1.3.c), with exceptions noted in the control Room Habitability Analysis, Revision 2 (Reference'4).

LCQ Operability of the CBEVS instrumentation ensures that the control room operators will be protected from hazarde external to the control room, consistent with the assumptions in the various analyses, through the prompt detection and initiation of the necessary protective actions cf the system.-

Aeolicability The instrumentation associated with the Radiation Protection Mode of the CBEVS is required to be operable to automatically detect and initiate the Radiation / Smoke Protection Mode of operation during times when the potential exists for events which may result in the release of radioactive materials to

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1 the environment, up to and including design basis accidents. The specific

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radiological _ release events for which the system must provide a mitigating function are discussed in the bases of Technical Specification 3.7.2.

The instrumentation associated with the chlorine Protection Mode of the CBEVS is required to be operable to automatically detect and initiate-the internal recirculation mode of operation any time the chlorine tank car is within the exclusion area.

The instrumentation associated with the External Smoke Protection function of the CBEVS is required to be operable to automatically detect and initiate the Radiation (Smoke) Protection Mode of operation during the same conditions as the Radiation Protection function. This ensures that habitability of the control room is maintained during times when a radiological release could potentially occur.

Actions Radiation Protection two control room air inlet radiation monitors measure radiation levels in the inlet ducting of the main control room. A high radiation level automatically initiates the radiation protection mode of operation. Both channels are required to be OPERABLE to ensure that no single instrument failure can preclude the initiation of the radiation protection function of the control room emergency ventilation system. The loss of a single detector means that the CBEVS reliability is reduced because a single failure in the OPERABLE subsystem could result in reduced or lost system capability. The 7 day out of service time is based on the low probability of a design basis accident and a single failure occurring during this time period, and the capability of the remaining instrumentation subsystem to provide the required isolation and is consistent with the out of service times allowed for loss of redundancy at the-system level.

The loss of both detectors means that the automatic detection / isolation function of the radiation protection system is lost. Placing the CBHVAC System in the Radiation Protection Mode is a suitable compensatory action to ensure that the automatic radiation protection function is not lost, chlorine Protection The chlorine detection / isolation instrumentation is organized into two trip i systems, with one trip-system (remoto) located-near the chlorine tank car and the other located in the control building intake plenum (local). Each trip system contains two trip subsystems, with two detectors (one from each division).in each trip subsystem. Both trip subsystems in each trip system are required-to be operable any time the chlorine tank-car is within the exclusion area to ensure adequate protection for the control room under postulated toxic gas events.

l~ The chlorine detectors in each trip system are arranged in a one-out-of-two-

' taken-twice conflguration. One detector from each of the trip subsystems in a.

trip system must actuate to initiate the automatic detection / isolation ,

function. The loss of a single chlorine detector means that the CBEVS-reliability is reduced because a single failure in the remaining OPERAELE trip subsystem detector could result in reduced or lost system capability. The 7 day out of service time is based en the low probability of a design basis

! chlorine gas event and a single active failure occurring during this time l period, and the capability of the remaining detectors to provide the required isolation capabilities. The out of service time is consistont with the out of service time allowed-for loss of redundancy at the system level.

The loss of both detectors in any t rip subsystem means that the automatic protection function of the chlorino detection / isolation system is lost.

Placing the CBHVAC System in the chlorine Protection Mode, through-the use of

,4 control switches to close the appropriate dampers, ensures that the control room envelope is protected, while at the same time allowing valid radiation or smoke signal to initiate appropriate protective actions. Operation in this mode is not limited in duration provided that either trip system remains, functional to ensure that the override function of the Ohlorine Protection Hode is not lost.

Smoke Protection Automatic detection / isolation of tha control room envelope in response to an  ;

external smoke event is dependant on the response of ionization detectors in Zones 4 and 5 of the Control Building. Multiple detectors in each of the-zones provide the detection / isolation capability; however, detection by one detector in both zones is required to initiate the isolation function. .

-l Having less than two detectors in a zone means the system reliability is reduced due to the loss of redundant detection capability in that zone.' ~j Allowing continued operation for up to 7 days with less than two OPERABLE l detectors in either or both zones is an acceptable out of service time i considering the low probability of an external smoke event and the fallore of the remaining detector during this time period, and the capability of tl.a remaining instrumentation to provide the required isolation. The out of service time is consistent with the out of service times allowed for loss of redundancy at the system level.

With less than one detector OPERABLE in either or both zones, the automatic detection / isolation function of the external smoke protection system is lost. ,

Placing the CBEVS in the Radiation (Smoke) Protection Mode is a suitable compensatory action to ensure that the automatic external smcke protection function is not lost.

surveillances Radiation Protection Performance of the CHANNEL CHECK once overy day ensures that a gross f ailure of the instrumentation has not occurred; thus, it is key to verifying the instrumentation continues to operate properly between each CHANNEL CALIBRATION. The CHANNEL CHECK frequency is consistent with that performed for other radiation monitors with isolation functions.

The CHANNEL FUNCTIONAL TEST is performed on each required channel to_ ensure

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that the entire channel'will-perform the intended function. The Control Room Habitability Analysis defines the specific actions to be satisfied by the radiation actuation instrumentation. The monthly frequency of the CHANNEL FUNCTIONAL TEST is consistent with that performed for other radiation monitors with isolation functions.

The CHANNEL CALIBRATION verifies the channel responds to the measured parameter within the necessary range and accuracy. CHANNEL CALIBRATION leaves the channel adjusted to ensure consistency with the system assumptions (Reference 5). The frequency of the calibration is consistent with the frequency of calibration of other radiation monitors with isolation functions.

Chlorine Protection The CHANNEL FUNCTIONAL TEST is performed on each required channel to ensure that the entire channel will perform the intended function. The Control Room Habitability Analysis defines the specific actions to be satisfied by the chlorine isolation instrumentation. The monthly frequency of-the CHANNEL FUNCTIONAL TEST is consistent with the' testing frequencies performed by other utilities with this type of instrumentation.

The CHANNEL CALIBRATION of the trip units provides a check of the' instrument loop and the sensor when the sensor is replaced. The test verifies the

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calibration of the existing sensor prior to removal and performs an installation calibration of the new sensor, including a complete channel calibration with the new censor installed, to verify ths channel responds tc, the measured parameter within the necessary range and accuracy. The CHANNEL CALIBRATION leaves the channel adjusted to ensure consistency with the system assumptions (Reference 6).

The chlorine detectors use an amperometric sensor consisting of a platinun cathode and silver anode joined by an electrolytic salt bridge, all enclosed in a permeable membrane. This design eliminates the majority of the maintenance required on previous detectors. The detectors have been in service at other facilities and have provided reliable service. The annual replacement and calibration are based on a manufacturer recommendation. The adequacy of the replacement interval has been confirmed through discust. ions with other utilities.

Smoke Protection The CRANNEL FUNCTIONAL TEST for the Smoke Protection instrumentation is consistent with the testing performed in accordance with the existing Fire Detection Instrumentation requirements. CRANNEL CALIBRATION is performed in accordance with the requirements of the CBEVS System specification (4.7.2).

References

1. la CFR 50, Appendix A, General Design Criteria 19, Control Room.

2. kegu?atory Guide 1.95, Revision 1, Protection of Nuclear Power Plant Control Room Operators Against on Accidental Chlorine Release.

3. Opdated FSAR, Brunswick Steam Electric Plant, Units 1 & 2.

4. NUS-3697, Revision 2, February 1983, Control Room Habitability Analysis.

5. CP&L Calculation 01534A-248, Control Room Radiation Monitor Setpoint Evaluation.

6. BNP Design Basis Document (DBD)-37, control Room Heating, Ventilation, and Air conditioning System, i

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