ML20206K112
ML20206K112 | |
Person / Time | |
---|---|
Site: | Millstone ![]() |
Issue date: | 03/05/1999 |
From: | NORTHEAST NUCLEAR ENERGY CO. |
To: | |
Shared Package | |
ML20206K062 | List: |
References | |
NUDOCS 9905130071 | |
Download: ML20206K112 (14) | |
Text
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Verified Rgvision 7sW ipri'i?.iis..il'sgy PLANT SYSTEMS InitiallD//
Date d G
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34!99
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d BASES
v CONTROL ROOM EMERGENCY VENTILATION SYSTEM (Continued)'
3/4.7.7
~. : h......c.v i L1HITING CONDIT10N'FOR OPERATION Two independent control room emergency air filtration systems are regulypd to be operable to ensure that at least one is available in the event.;the other s
3 i
system is disabled.
..t A control room emergency air filtration system is OPERABLE when"the ass $ fate
^
a.
Fan is OPERhBLE; HEPA filters and charcoal adsorbers are not excessively restrict'ing floi/ and b.
are capable of performing their filtration functions; and moisture separator, heater, ductwork, valves, and dampers are OPERABLE,'and c.
air circulation can be maintained.
bobi.tabillt'r The integrity of the contro1Troom(boundary (i.e., walls, floors, ceilings, ductwork, and access doors)k(is f6vered tpf LIMITINS/ CONDITION OFA
_ rnust. be. tom'ntain eci suc.h that the cent.Rol 3.
i U,d '
h bitab'lity 2ous c.an be. maintosned at its ([
sitive pEev.ut e. W yred to be Mi% in APPLICABILITY ggg e
i 1
- Prehritation mode..
In MODES I, 2, 3, 4, 5, an i
ACTIONS Modes 1, 2. 3. and 4, y
m c
With one controllroom emergency air filtration system.. inoperable, a,ction must'be takennto restore the inoperable: system to.jan.0PERABLE status,within -
theremainingcontrolroomemergency.' air' filtration 7 days.. In this condition,i system is adequate to perform the control room protection ~fcnctiori.. Jfowever, the because a single failure.in thh,0PERABLE train overall. reliability is reduced could result in a loss of the control room emergency air filtration system function. The 7-day completion time is based on the low probability of a DBA occurring.during this time period, and the ability of the-remaining train to provide.the required capability.
If tiie inoperable train cannot be restored to an OPERABLE status within 7 days, the unit must be placed 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 within 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 />. These completion times are reasonable, based on operating experience, to reach the required ~ unit conditions from full power conditions in an orderly manner and without challenging unit systems.
With the, c.ontrc:d row habitokilitg oundag not intact.
b
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'Ogcudy gb design requiremente,beh sa,n3 c,e ge consta go,
$ st ern oct inopecable. anel entry into 3D trution 3
S Pec.ificotts,on 3,g g gg, Amendment No.136 S B 3/4 7-12 MILLSTONE - UNIT 3 9905130071990504 2
PDR ADOCK 05000423 i P
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WY.T-Y' ENS' April 10, 1997 m. --.
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1 BASES A
.:;f 3/4.7.7 CONTROL ROOH ENERGENCY VENTILATION SYSTEM (Continued)
SURVEILLANCE REOUIREMENTS (Continued) iodide penetration of less than 0.1750. The laboratory analysis is required to be performed within 31 days after removal of the sample. ANSI H510-1980 is used in lieu of ANSI H510-1975 referenced in Revision 2 of Regulatory Guide 1.52.-
The maximum survel'llance interval is 900 hours0.0104 days <br />0.25 hours <br />0.00149 weeks <br />3.4245e-4 months <br /> per Surveillance Requir~ement 4.0.2.
The 720 hours0.00833 days <br />0.2 hours <br />0.00119 weeks <br />2.7396e-4 months <br /> of operation requirement originates from Nuclear Regulatory Guide 1.52, Table 2, Note C.
This testing ensures that the charcoal adsorbency capacity has not degraded below acceptable limits as well as providing,tr' ending,,
data.
's
~
4.7.7.e.1 This surveillance verifies that the pressure drop across 'the ' combined HEPA filters and charcoal adsorbers banks at less than 6.75 inches water gauge when the system is operated at a flow rate of 1,120 cfm i 20%. The frequency is at least once 'per REFUELING INTERVAL.
4.7.7.e.2' This surveillance verifies that the system maintains the control room at a positive pressure of greater than or equal to 1/8 inch water gauge at less than or equal to a pressurization flow of 230 cfm relative to adjacent areas during system operation. The frequency is at least once per REFUELING INTERVAL.
The intent of this surveillance is to verify the ability of the control room emergency air filtration system'to tain a positive pressure while running. in the filt r d pressurization mode. This cap eility is ndepenoent i om In req 1 ement/ regardingJhe cont.rof room g/essurizat n system con ined Teci icalfpecificatji fi 3/4.7.8/f
{LLST0HE-UNIT 3 B 3/4 7-15 Amendment Ho.136 p
ruun a n a e c.na ayu m,rgngyy m.pye GASES 3, tg..; p.i W ff
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n2/.fr7.7 CONTROL ~ ROOM EMERGENCY VENTILATION SYSTEM (Continued)
SURVEILLANCEREQUIREMENTS(Continued) 4.7.7.a Following the complete or partial replacement of a charcoal adsorber bank, the' operability of the cleanup system should be. confirmed. This is accomplished by verifying that the cleanup system' satisfied the in-place penetration and bypass' leakage testing acceptance criterion of less.than 0.05% in accordance with ANSI N510-1980 for a halogenated hydrocarbon refrigerant. test gas while operating the system at a flow of 1,120 cfm i 20%.
References:
- u.,
~
(1) Nuclear Regulatory Guide 1.52, Revision 2 o
i (2
MP3 UFSAR, lable 1.8-1, NRC Regulatory Guide 1.52 (3
NRC Generic Letter 91-P...-
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conorrioN REfbs.Y c d)
- M3 -99 62.'7l M (3/47718
'CONTROLNR00M ENVEL PESPRESSURIZATION-SYSTEM BACKGROUND l
The control room envelope pressurization system provides a protected environment from which operators can control the unit following an uncontrolled release of radioactivity.
3 The c'ontrol room envelope pressurization system consists of. two banks of air bottles with its associated piping, instrumentation, and controls.
Each bank is capable of providing the control room area with one-hour of, air following any event with the potential for radioactive releases.
Normal Operation During normal operations, the control room envelope pressurization system is required to be on standby.
Post Accident Operation The control room ' envelope pressurization system is required to operate during post-accident operations to ensure the control room will remain habitable during and following accident conditions.
The sequence of events which occurs upon receipt of a control building duct to the con) trol room envelope ~is< described in Bases Sectioh 3/4.7.7. isola Verifie R vision %fM
~
Initial Datefh1N
.,MgLSTONE-UNIT 3 8 3/4 7-17 Amendment No. 136 C#
)
, n@%y April 10e;1997 Vcrified Reyision N f-5-ff PLANT SYSTEMS InitiallDA Datdb'C (0)
BASES
(.;:y.
~
3/4.7.8 CONTROL ROOH ENVELOPE PRESSURIZATION SYSTEM (Continue,d)
APPLICABLE SAFETY ANALYSIS The OPERABILITY of the control room envelope pressurization system ensures that:
(1) breathable air is supplied to the control room, instrumentationerack room, and computer room, and (2) a positive pressure is created and mainta.ined.
within the control room envelope during control building isolation:for the first hour.following any event with the potential for radioactive releases. lEach system is capable of providing an adequate air supply to the control room for one hour following an initiation of a control building isolation signal. After one hour, operation of the control room emergency ventilation system would be initiated.
LIMITING CONDITION FOR OPERATION Two independent control room envelope pressurization systems are required to be operable to ensure that at least one is available in the event the other system is disabled.
A control room envelope pressurization system is OPERABLE when the associated:
a.
air storage bottles are OPERABLE; and
]
b.
piping and valves are OPERABLE.
o adfli d he integrity of the control room oundary (i.e., walls, floors, ceilings, cuctwork, and access doors) must be maintained.
APPLICABILITY In MODES 1, 2, 3, 4, 5, and 6.
4 ACTIONS With one control room envelope pressurization system inoperable, action must a.
.be taken either:
(1) to restore the inoperable system to an OPERABLE status within 7 days, or (2) to initiate and maintain operation of an OPERABLE control room emergency air filtration system in the recirculation mode, or (3) to place the unit in HOT STANDBY within six hours and COLD SHUTDOWN wittiin the next 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br /> and suspend all-operations involving CORE ALTERATIONS or positive reactivity changes.
For ACTION 3.7.8.a.1, the remaining control room envelope pressurization system is. adequate to. perform..the control room protection function.
However, the overall.rel:iability is reduced because a single failure in
+
f(
Amendment No.136 MgLSTONE-UNIT 3 B 3/4 7-18
PLANT SYSTEMS BASES 3/4.7.8-CONTROL ROOM ENVELOPE PRESSURIZATION SYSTEM (Continued)
ACTIONS (Continued) the OPERABLE train could result in a loss of the control room envelope pressurization system. The 7-day completion time is based on the low probability of a design basis accident occurring during this. time period and the' ability of the remaining train to provide the required capability.
'For ACTION 3.7.8.a.2, initiating and maintaining operation of an.' OPERABLE ttrain of the control room emergency air filtration: system:in.the recirculation mode ensures that (i) any inleakage cassa; result of loss pressurization, will be filtered.from the. initiation.of,the; event,.and
"(ii-) active failures of thatutrain.will be readily:dete'cted.
.To.. meet the N re'quirements ofithis action statement,.the:controltroomsenergency: air Tfil tration' system tould ebe manually, pl aced.in 'either theclockrecircul ation
' mode or'the r'ecir'culation' with makeup air mode. aTheedirculation.with u
. makeup %iNde' is used it'a Yefresh the control-:roomiairesupplyn3hile in the recirculation with makeup air mode, if a CBI signal.is received, the fresh air makeup would be automatically isolated and the filters aligned to the 100% recirculation mode.
For ACTION 3.7.8.a.3, the completion times for the unit to be placed in HOT STANDBY and COLD SHUTDOWN are reasonable. They are based on operating s
experience, and they permit the unit to be placed in the required conditions fro ~ full power conditions in an orderly manner and without challenging unit systems.
Stud tensioning may continue in MODE 6 and a MODE change to MODE 5 is permitted with a control room envelope pressurization system inoperable (Reference 1).
b.
With both control room envelope pressurization systems inoperable, action must be initiated within one hour to. restore one inoperable system to an OPERABLE status and either (1) initiate and maintain operation of an OPERABLE control room emergency air filtration system in the recirculation mode, or (2). place the unit in HOT STANDBY within six hours and COLD SHUTDOWN within the next 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br /> and suspend all operations involving CORE ALTERATIONS or positive reactivity changes.
The rationale for ACTIONS 3.7.8.b.1 and 3.7.8.b.2 are the same as those for ACTIONS 3.7.8.a.2 and 3.7.8.a.3, respectively.
due t operability of both trains of the control room envelone 7
pressurization system the conoitions ana requirea acT. ions assigned (LCO 3.7.7 are no". reau red to be entered.
C IS IN DEPENDE NT PgoM THE RENREMEMTS REGARtnNQ THG cowTgoL Roos gME%EMG VENTILehoM S YS TEM
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couTmn eo pa Lco 3,g,7 nt
'M LSTONE - UNIT 3 8 3/4 7-19 Amendment No.135 e
.c g, 3,;.pgg April 10, 1997 PLANT SYSTEMS BASES
/l
\\.,
3/4.7.8 CONTROL ROOM ENVELOPE PRESSURIZATION SYSTEM (Continued)
ACTIONS (Continued)
ACTIONS a.2 and b.1 of Limiting. Condition for Operation 3.7.8 req'uire that-an OPERABLE control room emergency filtration system be placed.i.n the recirculation mode. Under nomal plant conditions to meet this requirement, the system would be placed in s'ervice in the recirculation with makeup air.
In the event This makeup air is used to refresh the control room envelope.-
of a design basis accident (including control building isolation), with the filtration system operating in.the recirculation with makeup air mode, the makeup air is automatically isolated and the filtration system goes into a 100% recirculation mode. Although no positive pressure isi maintained in this alignment, it ensures that unfilterable noble gases are not forced into the envelope. The recirculation mode ensures that radiciodines introduced to the envelope are continuously filtered out. After one hour, the filters could be manually placed in the pressurization mode if radiological ditions permit.
a p
SURVEILLANCE REQUIREMENTS
_4.7.8.a This surveillance requires verification that the air bottles are properly 6) pressurized. Verifying that the air bottles are pressurized to greater than or
~'/
equal to 2200 psig will ensure that a control room envelope pressurization system The frequency of the will be capable of supplying the required flow rate.
surveillance is at least once per 7 days. It is based on engineering judgment and has been.shown to be appropriate through operating experience.
4.7.8.b
.This surveillance requires. verification of the correct position of each valve (manual, power: operated, or automatic) in the control room -envelope pressurization' system flow path.
It helps ensure that the control room envelope pressurization system is capable' of performing its intended safety function by-The surveillance applies to verifying that an appropriate flow path will exist.
those valves that could be mispositioned. This surveillance does not apply to valves that have been locked, sealed, or secured in position, because these positions are verified prior to locking, sealing, or securing.
The frequency of the surveillance is at least once per 31 days on a STAGGERED TEST BASIS.
It is based on engineering judgment and has been shown to be appropriate through operating experience.
Verified R9 vision %BM initialfDk DaidbCIC )
Amendmen No.136 -
MILLSTONE - UNIT 3 8 3/4 7-20 0500
/..
1 Ca 3 # 11 l
Proposed Technical Specification Bases 3/4.7.7 & 3/4.7.8 Change l
Insert "A", Addition ofNew Paragraph With the control room habitability boundary not intact in accordance with design requirements, both trains of the Control Room Envelope Pressurization System are inoperable and entry into 3.0.3 is required.
I ofI
Docket No. 50-423--
B17770 Millstone Nuclear Power Station, Unit No. 3.
Proposed Revision to Technical Specification Bases Sections 3/4.7.7 and 3/4.7.8 (PTSCR 3-5-99)
Retyped Technical Specification Pages 1
i
)
1
' May;1999 -
l
PLANT SYSTEMS BASES 3/4.7.7 CONTROL ROOM EMERGENCY VENTILATION SYSTEM (Continued)
LINITING CONDITION FOR OPERATION Two independent control room emergency air filtration systems are required to be operable to ensure that at least one is available in the event the other system is disabled.
A control room emergency air filtration system is OPERABLE when the associated:
a.
Fan is OPERABLE; b.
HEPA filters and charcoal adsorbers are not excessively restricting flow and are capable of performing their filtration functions; and c.
moisture separator, heater, ductwork, valves, and dampers are OPERABLE, and air circulation can be maintained.
The integrity of the control room habitability boundary (i.e., walls, floors, ceilings, ductwork, and access doors) must be maintained such that the j
control building habitability zone can be maintained at its design positive pressure if required to be aligned in the filtration pressurization mode.
{
APPLICABILITY i
i In MODES 1, 2, 3, 4, 5, and 6.
ACTIONS Modes 1. 2. 3. and 4 With one control room emergency air filtration system inoperable, action must be taken to restore the inoperable system to an OPERABLE status within 7 days.
In this condition, the remaining control room emergency air filtration system is adequate to perform the control room protection function. However, the overall reliability is reduced because a single failure in the OPERABLE train could result in a loss of the control room emergency air filtration system function. The 7-day completion time is based on the low probability of a DBA occurring during this time period, and the ability of the remaining train to provide the required capability.
If the inoperable train cannot be restored to an OPERABLE status within 7 days, the unit must be placed 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 within 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 />. These completion times are reasonable, based on operating experience, to reach the required unit conditions from full power conditions in an orderly manner and without challenging unit systems.
With the control room habitability boundary not intact in accordance with design requirements, both trains of the Control Room Emergency Air Filtration System are inoperable and entry into Specification 3.0.3 is required.
NILLSTONE - UNIT 3 B 3/4 7-12 Amendment No. JM,
0648 i
J
e PLANT SYSTEMS BASES 3/4.7.7 CONTROL ROOM EMERGENCY VENTILATION SYSTEM (Continued)
SURVEILLANCE REQUIREMENTS (Continued) iodide penetration of less than 0.175%. The laboratory analysis is required to be performed within 31 days after removal of the sample. ANSI N510-1980 is used in lieu of ANSI N510-1975 referenced in Revision 2 of Regulatory Guide 1.52.
The maximum surveillance interval is 900 hours0.0104 days <br />0.25 hours <br />0.00149 weeks <br />3.4245e-4 months <br />, per Surveillance Requirement 4
4.0.2.
The 720 hours0.00833 days <br />0.2 hours <br />0.00119 weeks <br />2.7396e-4 months <br /> of operation requirement originates from Nuclear Regulatory Guide 1.52, Table 2, Note C.
Thir testing ensures that the charcoal adsorbency capacity has not degraded below acceptable limits as well as providing trending data.
4.7.7.e.1 This surveillance verifies that the pressure drop across the combined HEPA filters and charcoal adsorbers banks at less than 6.75 inches water gauge when the system is operated at a flow rate of 1,120 cfm i 20%. The frequency is at least once per REFUELING INTERVAL.
4.7.7.e.2 This surveillance verifies that the system maintains the control room at a positive pressure of greater than or equal to 1/8 inch water gauge at less than or equal to a pressurization flow of 230 cfm relative to adjacent areas during system operation. The frequency is at least once per REFUELING INTERVAL.
The intent of this surveillance is to verify the ability of the control room emergency air filtration system to maintain a positive pressure while running in the filtered pressurization mode.
I l
l l
)
MILLSTONE - UNIT 3 8 3/4 7-15 Amendment No. 17J 0049
PLANT SYSTEMS BASES 3/4.7.7 CONTROL ROOM EMERGENCY VENTILATION SYSTEM (Continued)
SURVEILLANCE REOUIRENENTS (Continued) 4.7.7.a Following the complete or partial replacement of a charcoal adsorber bank, the operability of the cleanup system should be confirmed.
This is accomplished by verifying that the cleanup system satisfied the in-place penetration and bypass leakage testing acceptance criterion of less than 0.05% in accordance with ANSI N510-1980 for a halogenated hydrocarbon refrigerant test gas while operating the system at a flow of 1,120 cfm i 20%.
References:
(1)
Nuclear Regulatory Guide 1.52, Revision 2 j
(2)
MP3 UFSAR, Table 1.8-1, NRC Regulatory Guide 1.52 (3)
(4)
Condition Report (CR) #M3-99-0271 l
)
1 3/4.7.8 CONTROL ROOM ENVELOPE PRESSURIZATION SYSTEM l
BEKGROUND The control room envelope pressurization system provides a protected l
environment from which operators can control the unit following an uncontrolled release of radioactivity.
I The control room envelope pressurization system consists of two banks of air i
bottles with its associated piping, instrumentation, and controls.
Each bank is capable of providing the control room area with one-hour of air following any event with the potential for radioactive releases.
Normal Operation j
During normal operations, the control room envelope pressurization system is required to be on standby.
Post Accident Operation The control room envelope pressurization system is required to operate during post-accident operations to ensure the control room will remain habitable 3
during and following accident conditions.
The sequence of events which occurs upon receipt of a control building
)
isolation (CBI) signal or a signal indicating high radiation in the air supply duct to the control room envelope is described in Bases Section 3/4.7.7.
NILLSTONE - UNIT 3 B 3/4 7-17 Amendment No JM,
oeso
PLANT SYSTENS BASES
~
3/4.7.8 CONTROL ROOM ENVELOPE PRESSURIZATION SYSTEM (Continued)
APPLICABLE SAFETY ANALYSIS The OPERABILITY of the control room envelope pressurization system ensures that:
(1) breathable air is supplied to the control room, instrumentation rack room, and computer room, and (2) a positive pressure is created and maintained within the control room envelope during control building isolation for the first hour following any event with the potential for radioactive releases.
Each system is capable of providing an adequate air supply to the control room for one hour following an initiation of a control building isolation signal. After one hour, operation of the control room emergency ventilation system would be initiated.
LINITING CONDITION FOR OPERATION Two independent control room envelope pressurization systems are required to be operable to ensure that at least one is available in the event the other system is disabled.
A control room envelope pressurization system is OPERABLE when the associated:
a.
air storage bottles are OPERABLE; and b.
piping and valves are OPERABLE.
The integrity of the control room habitability boundary (i.e., walls, floors, l
ceilings, ductwork, and access doors) must be maintained.
APPLICABILITY In MODES 1, 2, 3, 4, 5, and 6.
ACTIONS a.
With one control room envelope pressurization system inoperable, action must be taken either:
(1) to restore the inoperable system to an OPERABLE status within 7 days, or (2) to initiate and maintain operation of an OPERABLE control room emergency air filtration system in the recirculation mode, or (3) to place the unit in HOT STANDBY within six hours and COLD SHUTDOWN within the next 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br /> and suspend all operations involving CORE ALTERATIONS or positive reactivity changes.
For ACTION 3.7.8.a.1, the remaining control room envelope pressurization system is adequate to perform the control room protection function.
However, the overall reliability is reduced because a single failure in NILLSTONE - UNIT 3 83/47-18 Amendment No, #7, oeso
~
PLANT SYSTEMS BASES 3 /4. 7.'8 CONTROL ROOM ENVELOPE PRESSURIZATION SYSTEM (Continued)
ACTIONS (Continued) the OPERABLE train could result in a loss of the control room envelope pressurization system. The 7-day completion time is based on the low probability of a design basis accident occurring during this time period and the ability of the remaining train to provide the required capability.
For ACTION 3.7.8.a.2, initiating and maintaining operation of an OPERABLE train of the control room emergency air filtration system in the recirculation mode ensures that (i) any inleakage, as a result of loss pressurization, will be filtered from the initiation of the event, and (ii) active failures of that train will be readily detected. To meet the requirements of this action statement, the control room emergency air filtration system could be manually placed in either the 100% recirculation mode or the recirculation with makeup air mode. The recirculation with makeup air mode is used to refresh the control room air supply. While in the recirculation with makeup air mode, if a CBI signal is received, the fresh air makeup would be automatically isolated and the filters aligned to the 100% recirculation mode.
For ACTION 3.7.8.a.3, the completion times for the unit to be placed in HOT STANDBY and COLD SHUTDOWN are reasonable. They are based on operating experience, and they permit the unit to be placed in the required conditions from full power conditions in an orderly manner and without challenging unit systems.
Stud tensioning may continue in MODE 6 and a MODE change to MODE 5 is permitted with a control room envelope pressurization system inoperable (Reference 1).
b.
With both control room envelope pressurization systems inoperable, action must be initiated within one hour to restore one inoperable system to an OPERABLE status and either (1) initiate and maintain operation of an OPERABLE control room emergency air filtration system in the recirculation mode, or (2) place the unit in H0T STANDBY within six hours and COLD SHUTDOWN within the next 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br /> and suspend all operations involving CORE ALTERATIONS or positive reactivity changes.
The rationale for ACTIONS 3.7.8.h.1 and 3.7.8.b.2 are the same as those for ACTIONS 3.7.8.a.2 and 3.7.8.a.3, respectively.
Inoperability of both trains of the control room envelope pressurization system is independent from the requirements regarding the control room emergency ventilation system contained in LC0 3.7.7.
MILLSTONE - UNIT 3 8 3/4 7-19 Amendment No. JM,
0060
4 PLANT SYSTEMS BASES
~
3/4.7.8 CONTROL ROOM ENVELOPE PRESSURIZATION SYSTEM (Continued)
ACTIONS (Continued)
ACTIONS a.2 and b.1 of Limiting Condition for Operation 3.7.8 require that an OPERABLE control room emergency filtration system be placed in the recirculation mode. Under normal plant conditions to meet this requirement, the system would be placed in service in the recirculation with makeup air.
This makeup air is used to refresh the control room envelope.
In the event of a design basis accident (including control building isolation), with the filtration system operating in the recirculaticn with makeup air mode, the makeup air is automatically isolated and the filtration system goes into.a 100% recirculation mode. Although no positive pressure is maintained in this alignment, it ensures that unfilterable noble gases are not forced into the envelope. The recirculation mode ensures that radiciodines introduced to the envelope are continuously filtered out. After one hour, the filters-could be manually placed in the pressurization mode if radiological conditions permit.
With the control room habitability boundary not intact in accordance with
- design requirements, both trains of the Control Room Envelope Pressurization System are inoperable and entry into 3.0.3 is required.
SURVEILLANCE RE0UIRENENTS 4.7.8.a 1
This surveillance requires verification that the air bottles are properly J
pressurized.
Verifying that the air bottles are pressurized to greater than or equal to 2200 psig will ensure that a control room envelope pressurization system j
will be capable of supplying the required flow rate. The frequency of the surveillance is at least once per 7 days.
It is based on engineering judgment and has been shown to be appropriate through operating experience.
1 4.7.8.b i
This surveillance requires verification of the correct position of each i
valve (manual, power operated, or automatic) in the control room envelope I
pressurization system flow path.
It helps ensure that the control room envelope
)
pressurization system is capable of performing its intended safety function by 1
verifying that an appropriate flow path will exist. The surveillance applies to 1
those valves that could be mispositioned. This surveillance does not apply to-
)
valves that have been locked, sealed, or secured in position, because these j
positions are verified prior to locking, sealing, or securing.
The frequency of the surveillance is' at least once per 31 days on a STAGGERED TEST BASIS.
It is based on engineering judgment and has been shown to be appropriate through operating experience.
NILLSTONE - UNIT 3' B 3/4 7-20 Amendment No. JM,
oeso j