ML20217E430

Proposed Tech Specs,Revising Requirements for Containment Penetrations During Refueling Operations

ML20217E430
Person / Time
Site:	Sequoyah
Issue date:	10/12/1999
From:	TENNESSEE VALLEY AUTHORITY
To:
Shared Package
ML20217E428	List: ML20217E421 ML20217E430
References
NUDOCS 9910190247
Download: ML20217E430 (14)

Text

'

ENCLOSURE 2 TENNESSEE VALLEY AUTHORITY SEQUOYAH PLANT (SQN)

UNITS 1 AND 2 PROPOSED TECHNICAL SPECIFICATION (TS) CHANGE MARKED PAGES I.

AFFECTED PAGE LIST Unit 1 3/4 9-4 B 3/4 9-1 Unit 2 3/4 9-5 B 3/4 9-1 II.

MARKED PAGES See attached.

l 9910190247 991012 DR ADOCK 05000327 PDR E2-1

)

j

,?

REFUELING OPERATIONS 3/4.9.4 CONTAINMENT BUILDING PENETRATIONS LIMITING CONDITION FOR OPERATION 3.9.4 The containment building penetrations shall be in the following status:

a.

The equipment door closed and held in place by a minimum of four

bolts, R213 b.

A minimum of one door in each airlock is closed, or both doors of both containment personnel airlocks may be open if:

1.

One personnel airlock door in each airlock is capable of closure, and 2.

One train of the Auxiliary Building Gas Treatment System is OPERABLE in accordance with Technical Specification 3.9.12, and c.'Eachpenetratihpovidingdirectaccessfromthecontainment

~

~

~

h atmosphere to thToutside atmosphere shall be either:

1.

Closed by an isolation valve, blind flange, or manual valve, or 2.

Be capable of being closed by an OPERABLE automatic Containment Ventilation isolation valve:

APPLICABILITY:

During CORE ALTERATIONS or movement of irradiated fuel within the containment.

ACTION:

With the requirements of the above specification not satisfied, immediately suspend all operations involving CORE ALTERATIONS or movement of irradiated fuel in the containment building. The provisions of Specification 3.0.3 are not applicable.

SURVEILLANCE RE0VIREMENTS n(

~

~

R213 4.9.4 Each of the above required containment building penetrations shall be

' determined to be either in its required condition or capable of being closed by an OPERABLE automatic Containment Ventilation isolation valve once per 7 days during CORE ALTERATIONS or movement of irradiated fuel in the cos'ainment building by:

a.

Verifying the penetrations are in their required condition, or b.

Testing the Containment Ventilation isolation valves per the a16 a lica e portions of Specification 4.6.3.2.

V. T N.S O t Y.$

SEQUO AH D IT 1 3/4 9-4 Amendment No.12, 209 September 6, 1995

v

[.

3/4.9 REFUELING OPERAU.Qtil BASES 3/4.9.1 BORON CONCENTRATION The~1 imitations on reactivity conditions during REFUELING ensure that:

1) the reactor wil1l remain suberitical during CORE ALTERATIONS, and 2) a uniform boron concentration is maintained for reactivity. control in the water volume. having direct access to the reactor vessel. Maintaining the. listed valves in the closed position precludes an uncontrolled. boron dilution accident 1

by closing the flow paths for possible sources of unborated water. These limitations are consistent wit 5 the initial conditions assumed for the boron dilution incident in the accident analyses.

l L

3/4.9.2 INSTRUMENTATION l

The OPERABILITY of the source range. neutron flux monitors ensures that redundant monitoring capability is available to detect changes in

.the reactivity condition of the core.

1 3/4.9.3 DECAY TIME The minimum requirement for reactor subcriticality prior to movement of irradiated fuel assemblies in the reactor-pressure vessel ensures that suffi-cient ties has elapsed to allow the' radioactive decay of the short lived fis-sion products. -This decay time is consistent with the assumptions used in the accident analyses.

4 3/4.9.4 CONTAINMENT BUILDING PENETRATIONS The requirements on containment building penetration closure and OPERABILITY ensure that a release of radioactive material within containment will be restricted from leakage to the environment.

The OPERABILITY'and 1

closure restrictions are sufficient to restrict radicactive material release from a fuel element rupture based upon the lack of cortainment pressurization R213 potential while in the REFUELING MODE.

Both sets of the containment personnel airlock doors may be open during movement of irradiated fuel in contrinment and during core alterations provided one train of Auxiliary Building Gas Treatment System-(ABGTS) is available for manual-operation. The basis of this is that SQN is' analyzed for a fuel handling accident (FHA) in either the containment or

.the auxiliary building;' however, a manual ABGTS start may be necessary for a containment FHA. The requirement for an airlock door to be capable of closure is provided to allow for long-term recovery from a FHA in containment.

3/4.9.5 COMMUNICATIONS The requirement;for comanications capability ensures that refueling station personnel can be promptly informed of significant changes in the facility status or core reactivity conditions during CORE ALTERATIONS.

September 6, 1995

.SEQUOYAH - UNIT I B 3/4 9-1 Amendment No.209 l

l'

e-

. REFUELING OPERATIONS 3/4.9.4 CONTAINMENT BUILDING PENETRATIONS i

LIMITINGbONDITIONFOROPERATION 3.9.4 The containment building penetrations shall be in the following status:

a.

The equipment door closed and held in place by a minimum of four

bolts, R199 b.

A minimum of one door in each airlock is closed, or both doors of both containment personnel airlocks may be open if:

1.

One personnel airlock door in each airlock is capable of closure, and One train of the' Auxiliary' Building Gas Treatment System is - "

~

2.

OPERABLE in accordance with Technical Specification 3.9.12, and c.

Each penetrati n p viding direct access from the containment V atmosphere to t e outside atmosphere shall be either:

~

-~

1.

Closed by an isolation valve, blind flange, or manual valve, or

'2.

Be capable of being closed by an OPERABLE automatic Containment Ventilation isolation valve, j

s APPLICABILITY:

During CORE ALTERATIONS or' movement of irradiated fuel within the containment.

ACTION:-

With the requirements of the above specification not satisfied, immediately suspend all operations involving CORE ALTERATIONS or movement.of irradiated fuel in the containment ~ building. The provisions of Specification 3.0.3 are not applicable.

SURVEILLANCE REQUIREMENTS 4.9.4, Each of the above required containment building penetrations gall be Rt99 determined'to be either in its required conditidrror' capable of beingmed by an OPERABLE automatic Containment Ventilation isolation valve once per 7 days during CORE ALTERATIONS or movement of irradiated fuel in the containment building by:-

a.-

Verifying the penetrations are in their required condition, or b.

Testing the-containment Ventilation isolation valves per the applicable portions of Specification 4.6.3.2.

W 2 NJ E327 d~.I.

September 6, 1995 SEQUOYAH - UNIT 2 3/4 9-5 Amendment No.199

e-3/4.9 REFUELING OPERATIONS BASTS' 3/4.9.1 BORON CONCENTRATION l-The limitations on reactivity conditions during REFUELING ensure that:

1) the reactor will remain subcritical during CORE ALTERATIONS, and 2) : uni-form boron concentration is maintained for reactivity control in the water volume having direct access to the reactor vessel. Maintaining the listed valves in the closed position precludes an uncontrolled baron dilution accident by closing the flow paths for possible sources of unborated water. These limitations are consistent with the initial conditions assumed for the boron dilution incident in the accident analyses.

I 3/4.9.2 INSTRUMENTATION l

l

,The OPERABILITY of the source range neutron flux monitors ensures that j

redundant monitoring capability is available to detect changes in the l

reactivity condition of the core.

{

l DECAY TIME j

3/4.9.3 The minimum requirement for reactor subcriticality prior to movement of irradiated fuel assemblies in the reactor pressure vessel ensures that l

sufficient time has elapsed to allow the radioactive decay of the short lived fission products. "This decay time is consistent with the assumptions used in J

the accident analyses.

i

,,3/4.9.4 CONTAINMENT BUILDING PENETRATIONS l

l The requirements on containment building penetration closure and l

OPERABILITY ensure that a release of radioactive material within containment l

will be restricted from leakage to the environment. The OPERABILITY and closure restrictions are sufficient to restrict radioactive material release from a fuel element rupture based upon the lack of containment pressurization g199 potential while in the REFUELING MODE.

Both sets of the containment personnel L

airlock doors may be open during movement of irradiated fuel in containment and i

during core alterations provided one train of Auxiliary Building Gas Treatment i

System (ABGTS) is available for manual operation. The basis of this is that SQN is. analyzed for a. fuel handling accident (FHA) in either the containment or i

the auxiliary building; however, a manual ABGTS start may be necessary for a containment FHA.

The requirement for an airlock door to be capable' of closure

's orovidad_to_ allow for long-term recovery from a FHA in containment.

--on-h etr' 2)NICATIONS

^ii. s.-ii G

.J The requirement for communications capability ensures that refueling station personnel can be promptly informed of significant changes in the facility status or core reactivity conditions during CORE ALTERATIONS.

September 6, 1995 SEQUOYAH - UNIT 2 B 3/4 9-1

' Amendment No.199

1 f

-Insert 1 l

• . Penetration flow path (s) providing direct access from the contaihment atmosphere that transverse and terminate in the Auxiliary Building Secondary Containment Enclosure may be unisolated under administrative controls.

Insert 2 The LCO'is modified by a footnote allowing penetration flow paths with direct access from,the containment atmosphere to the Auxiliary Building Secondary Containment Enclosure.(ABSCE) to be unisolated under administrative controls.

These flow paths must be within'the ABSCE structure or in qualified piping that 1

constitutes the ABSCE boundary and either terminate or have an isolation device within the ABSCE.

Administrative controls ensure that 1) appropriate personnel are aware of the open status of the_ penetration flow path during' CORE ALTERATIONS or movement of. irradiated fuel assemblies within containment, 2) specified

. individuals are designated and readily available to isolate.the flow path:in theLevent of an FHA, and 3) one train _of the ABGTS is_ OPERABLE in accordance with Technical Specification 3.9.12.

As discussed above for-the containment airlock doors, the basis for this_ allowance is the SON analysis for an FHA in containment or the auxiliary building and the potential need for a manual start of'the ABGTS for an FHA in containment.

This allowance is' not applicable to the containment ventilation isolation flow patas because of the potential motive force associated with the containment purge system that could result in additional releases of' radioactivity.

Additionally, this allowance is not applicable to1those flow paths that terminate or are routed outside the ABSCE in piping that does not meet the requirements for an ABSCE boundary.

l l

l l^

i i

[ ' '.

e ENCLOSURE 3 TENNESSEE VALLEY AUTHORITY SEQUOYAH NUCLEAR PLANT (SQN)

UNITS 1 AND 2 PROPOSED TECHNICAL SPECIFICATION (TS) CHANGE REVISED PAGES I

l I.

AFFECTED PAGE LIST j

l Unit 1

)

l 3/4 9-4 B'3/4 9-1 B 3/4 9-2 Unit 2 3/4 9-5 B 3/4 9-1 B 3/4.9-2 II.

REVISED PAGES See attached.

E3-1

s

REFUELING OPERATION 1 3 /4. 9. 4 CONTAINME'fr BUILDING PENETRATIONS

< LIMITING CONDITION FOR OPERATION

'3.9.4L The containment building penetrations shall be in the following status:

a.

The equipment door closed and held in place by a minimum of four

bolts, L

b.

_A minimum of.one door in each airlock is closed,'and both doors of I

both containment personnel airlocks may be open if:

R213

{

1.

One personnel airlock door in each airlock is capable of I

closure, and 2.

One train of the Auxiliary Building Gas Treatment System is OPERABLE in accordance with Technical Specification 3.9.12, and c.

Each penetration

• providing direct access from the containment l

atmosphere to the outside atmosphere shall be either:

1.

Closed by an isolation valve, blind flange, or ranual valve, or 2.

Be capable of being closed by an OPERABLE automatic Containment ventilation isolation valve.

APPLICABILITY During CORE ALTERATIONS or movement of irradiated fuel within the containment.

ACTION:

With the requirements of the above specification not satisfied, immediately

suspend all operations involving CORE ALTERATIONS or movement of irradiated

' fuel:in the containment building. The provisions of Specification.3.0.3 are not applicable.

i 9URVEILLANCE REQUIREMENTS 4.9.4 Each of the above required containment building penetrations shall be determined to be either in its required condition or capable of being closed by en OPERABLE automatic Containment Ventilation isolntion valve once per 7 days R213 during CORE ALTERATIONS or movement of irradiated fuel is the containment building by:

.a.

Verifying the penetrations are in their required condition, or Lb.

Testing'the Containment Ventilation isolation valves per the R16 applicable portions of Specification 4.6.3.2.

Penetration flow path (s) providing direct access from the containment I

atmosphere that transverse and terminate in the Auxiliary Building Secondary Containment Enclosure may be unisolated under administrative controls.

SEQUOYAH - UNIT 1 3/4 9-4 Amendment No. 12, 209,

?

i t

w 1

3/4.9 REFUELING OPERATIONS BASES I

3/4.9.1 BORON CONCENTRATION i

i The limitations on reactivity conditions during REFUELING ensure that:

I

1) the reactor will remain suberitical during CORE ALTERATIONS, and 2) a uniform boron concentration is maintained for reactivity control in the water i

volume having direct access to the reactor vessel. Maintaining the listed valves in the closed position precludes an uncontrolled boron dilution accident I

by closing the flow paths for possible sources of unborated water.

These limitations are consistent with the initial conditions assumed for the boron dilution incident in the accident analyses.

3/4.9.2 INSTRUMENTATION The OPERABILITY of the source range neutron flux monitors ensures that redundant monitoring capability is available to detect changes in the reactivity condition of the core.

j j

3/4.9.3 DECAY TIME The minimum requirement for reactor subcriticality prior to movement of irradiated fuel assemblies in the reactor pressure vescel ensures that sufficient time has elapsed to allow the radioactive decay of the short lived fission products. This decay time is consistent with the ase_*ntjons used in the accident analyses.

3/4.9.4 CONTAINMENT BUILDING PENETRATIONS The requirements on containment building penetration closure and OPERABILITY ensure that a release of radioactive material within containment will be restricted from leakage to the environment. The OPERABILITY and 3

closure restrictions are sufficient to restrict radioactive material release from a fuel element rupture based upon the lack of containment pressurization j

potential while in the REFUELING MODE.

Both sets of the containment personnel airlock doors may be open during movement of irradiated fuel in containment and during core alterations provided one train of Auxiliary Building Gas Treatment R213

[

System (ABGTS) is available for manual operation. The basis of this is that l

SQN is analyzed for a fuel handling accident (FHA) in either the containment or j

the auxiliary building; however, a manual ABGTS start may be necessary for a j

containment FHA.

The requirement for an airlock door to be capable of closure is provided to allow for long-term recovery from a FHA in containment.

The LCO is modified by a footnote allowing penetration flow paths with direct access from the containment atmosphere to the Auxiliary Building Secondary Containment Enclosure (ABSCE) to be unisolated under administrative controls.

These flow paths must be within the ABSCE structure or in qualified piping that constitutes the ABSCE boundary and either terminate or have an isolation device a

within the ABSCE. Administrative controla ensure that 1) appropriate personnel l

are aware of the open status of the penetration flow path during CORE l

ALTERATIONS or movement of irradiated fuel assemblies within containment,

2) specified individuals are designated and readily available to isolate the l

flow path in the event of an FHA, and 3) one train of the ABGTS is OPERABLE in i

accordance with Technical Specification 3.9.12.

As discussed above for the containment airlock doors, the basis for this allowance is the SQN analysis for an FHA in containment or the auxiliary building and the potential need for a manual start of the ABGTS for an FHA in containment. This allowance is not applicable to the containment ventilation isolation flow paths because of the potential motive force associated with the containment purge system that could result in additional releases of radioactivity. Additionally, this allowance is not applicable to those flow paths that terminate or are routed outside the ABSCE in piping that does not meet the requirements for an ABSCE boundary.

SEQUOYAH - UNIT 1 B 3/4 9-1 Amendment No. 209,

REFUELING OPERATIONS BASES 3/4.9.5 COMMUNICATIONS, The requirement for communications capability ensures that refueling station personnel can be promptly informed of significant changes in the facility status or core reactivity conditions during CORE ALTERATIONS.

3/4.9.6 MANIPULATOR CRANE The OPERABILITY requirements for the manipulator cranes ensure that:

1) manipulatar. cranes will be used for movement of drive rods and fuel assemblies 2) each crane has sufficient load. capacity to lift a drive rod or fuel asser..oly, and 3) the core internals and pressure vessel are protected from excessive lifting force in the event they are inadvertently engaged during lifting operations.

3/4.9.7 CRANE TRAVEL - SPENT FUEL PIT AREA i

This specification is deleted.

R208 3/4.9.8 RESIDUAL HEAT REMOVAL AND COOLANT CIRCULATION The requirement that at least one residual heat removal (RHR) lcop be in operation ensures that; 1) sufficient cooling capacity is available to remove decay heat and maintain the water in the reactor pressure vessel below 140*F as required during the REFUELING MODE, and 2) sufficient coolant circulation is maintained through the reactor core to minimize the effects of a boron dilution incident and prevent boron stratification. The minimum required flow rate of R138 2000 gpm ensures decay heat removal, minimizes the probability of losing an RHR pump by air-entrainment from pump vortexing, and minimizes the potential for valve damage due to cavitation or chatter. Losing an RHR pump is a particular concern during reduced RCS inventory operation. The 2000 gpm value is limited by the potential for cavitation in the control valve and chattering in the 10-inch check valve.

The requirement to have two RHR loops OPERABLE when there is less than 23 feet of water above the reactor pressure vessel flang? ensures that a single failure of the operating RHR loop will not result in a complete loss of residual heat removal capability.

With the reactor vessel head removed and 23 feet of water above the reactor pressure vessel flange, a large heat sink is available for core cooling.

Thus, in the event of a failure of the operating RHR loop, adequato time is provided to initiate emergency procedures to cool the core.

l June 14, 1995

-SEQUOYAH - UNIT 1 B 3/4 9-2 Amendment No. 134, 167, 204

f6

,y a'

?

1 REFUELING OPERATIONS

~

! 3/4. 9.4 CONTAINMENT BUILDING PENETRATIONS a

3 2,

LIMITING CONDITION FOR' OPERATION L

3.9.4 The containment building penetrations shall be in the following status:

a.

-The equipment doorfclosed and held in place by a_ minimum of four l

. bolts, Eb.

A' minimum of one door'in each airlock is closed, or both doors of R199 j

both containment personnel airlocks may be open if:

l 1.

~One. personnel. airlock door in each airlock is capable of

closure,'and 2i One train of the Auxiliary Buil'ing Gas Treatment System is d

j

~

OPERABLE in accordance with Technical Specification 5.9.12, and c.

Each penetration

• providing direct access from the containment l

atmosphere to the outside atmosphere shall be either:

1,

. Closed by an isolation valve, blind flange, or manual valve, or t

2.

Be capable of being closed by an OPERABLE automatic Containment Ventilation isolation valve.

i APPLICABILITY: 'During CORE ALTERATIONS or movement of irradiated fuel within the containment.

ACTION:

l With the' requirements of the above specification not satisfied, immediately suspend all. operations involving CORE ALTERATIONS or movement of. irradiated fuel in the containment building

.The provisions of Specification 3.0.3 are not; applicable.

SURVEILLANCE-REQUIREMENTS ^

.4.9.4

.Each of the above required containment building penetrations shall be R199 determined to be either-in its required condition or capable of being closed by Jan OPERABLE. automatic Containment Ventilation isolation valve once per 7 days during CORE l ALTERATIONS or movement of-irradiated feel in the containment building by:

a.

Verifying the penetrations are in their required condition, or

-b.

' Testing the Containment Ventilation isolation valves per the applicable portions of Specification 4.6.3.2.

1*-

Penetration flow path (s) providing direct access from the containment atmosphere that transverse and terminate in the Auxiliary Building Secondary Containment Enclosure may be unisolated under administrative controls.

SEQUOYAH - UNIT 2 3/4 9-5 Amendment No. 199, l'

j

{

3/4.9 REFUELING OPERATIONS BASES 3/4.9.1 BORON CONCENTRATION The limitations on reactivity conditions during REFUELING ensure that:

1) the reactor will remain subcritical during CORE ALTERATIONS, and 2) a uniform boron concentration is maintained for reactivity control in the water volume having direct access to the reactor vessel. Maintaining the listed valves in the closed position precludes an uncontrolled boron dilution accident by closing the flow paths for possible sources of unborated water.

These limitations are consistent with the initial conditions assumed for the boron dilution incident in the accident analyses.

3/4.9.2 INSTRUMENTATION The OPERABILITY of the source range neutron flux monitors ensures that redundant monitoring capability is available to detect changes in the reactivity condition of the core.

3/4.9.3 DECAY TIME The minimum requirement for reactor subcriticality prior to movement of irradiated fuel assemblies in the reactor pressure vessel ensures that sufficient time has elapsed to allow the radioactive decay of the short lived fission products. This decay time is consistent with the assumptions used in the accident analyses.

3/4.9.4 CONTAINMENT BUILDING PENETRATIONS The requirements on containment building penetration closure and OPERABILITY ensure that a release of radioactive material within containment will be restricted from leakage to the environment. The OPERABILITY and closure restrictione are sufficient to restrict radioactive material release j

from a fuel element 1 pture based upon the lack of containment pressurization l

potential while in the REFUELING MODE.

Both sets of the containment personnel R199 airlock doors may be open during movement of irradiated fuel in containment and during core alterations provided one train of Auxiliary Building Gas Treatment System (ABGTS) is available for manual operation. The basis of this is that SQN is analyzed for a fuel handling accident (FHA) in either the containment or the auxiliary building; however, a manual ABGTS start may be necessary for a containment FHA.

The requirement for an airlock door to be capable of closure is provided to allow for long-term recovery from a FHA in containment.

The LCO is modified by a footnote allowing penetration flow paths with direct access from the containment atmosphere to the Auxiliary Building Secondary Containment Enclosure (ABSCE) to be unisolated under administrative controls.

These flow paths must be within the ABSCE structure or in qualified piping that constitutes the ABSCE boundary and either terminate or have an isolation device within the ABSCE.

Administrative controls ensure that 1) appropriate i

personnel are aware of the open status of the penetration flow path during CORE ALTERATIONS or movement of irradiated fuel assemblies within containment,

2) specified individuals are designated and readily available to isolate the flow path in the event of an FHA, and 3) one train of the ABGTS is OPERABLE in accordance with Technical Specification 3.9.12.

An discussed above for the containment airlock doors, the basis for this allowance is the SQN analysis for an FHA in containment or the auxiliary building and the potential need for a manual start of the ABGTS for an FHA in containment. This allowance is not applicable to the containment ventilation isolation flow paths because of the potential motive force associated with-the containment purge system that could result'in additional releases of radioactivity. Additionally, this allowance j

is not applicable to those flow paths that terminate or are routed outside the ABSCE in piping that does not meet the requirements for an ABSCE boundary.

SEQUOYAH - UNIT 2 B 3/4 9-1 Amendment No. 199,

El l'

j.

REFUELING OPERATIONS' i

l BASES l

l 3 /4.' 9. 5 ' COMMUNICATIONS-t l

The_ requirement for communications capability ensures that refueling

. station personnel can be promptly informed of significant changes in the

' facility status or. core reactivity conditions during CORE ALTERATIONS.

l 3/4.9.6 MANIPULATOR CRANE The OPERABILITY requirements for the manipulator cranes ensure that:

L1) manipulator cranes will be used for movement of drive rods and fuel' assemblies,-2).each crane has sufficient load capacity to lift a drive rod or fuel assembly, assembly, and 3),the core internals and pressure vessel are protected from excessive lifting force in the event they.are inadvertently engaged during~1ifting operations..

3/4.9.7 CRANE TRAVEL - SPENT FUEL PIT AREA R194 This specification is deleted.

3/4.9.8' RESIDUAL HEAT REMOVAL AND COOLANT CIRCULATION The requirement that at least one residual heat removal (RHR) loop be in operation ensures that;-1) sufficient cooling capacity is available to remove

' decay heat and maintain the water in the reactor pressure vessel below 140*F as required during the-REFUELING MODE, and 2) suffi' lent coolant circulation is maintained thru the reactor core to minimize the effects of a boron dilution incident and prevent boron stratification. The minimum required flow R121 rate of 2000 gpm ensures decay heat removal, minimizes the probability of-losing an RHR pump by air-entrainment from pump vortexing, and minimizes-the potential for valve damage due.to cavitation or chatter. Losing an RHR pump

'is a.particular concern during reduced RCS inventory operation. LThe 2000 gpm value is limited by the potential for cavitation in the control valve and

. chattering in the 10-inch check valve.

The requirement to have two RHR loops. OPERABLE when there is less than 23 feet of water above the reactor pressure vessel flange ensures that a single failure-of the operating RHR loop will not result in a complete loss of

-residual heat removal capability. With the reactor vessel head removed and 123 feet of water-above the reactor pressure vessel flange, a large heat sink is available for core cooling. Thus, in the event of a failure of the operating RHR loop, adequate. time is provided to initiate emergency procedures

.to. cool the core.

1 P

I June 14, 1995 SEQUONAH - UNIT 2 B 3/4 9-2 Amemdmemt No. 121, 157, 194

-