ML20092K220

Proposed Tech Specs,Changing Plant TS Bases Section 3/4.9.1 for Refueling B Concentration

ML20092K220
Person / Time
Site:	Seabrook
Issue date:	09/20/1995
From:	NORTH ATLANTIC ENERGY SERVICE CORP. (NAESCO)
To:
Shared Package
ML20092K214	List: ML20092K209 ML20092K220
References
NUDOCS 9509250282
Download: ML20092K220 (5)

Text

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• 3/4.9 REFUELING OPERATIONS l

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3/4.9.1 B TRATION DJSE6  ;

t conditions d Mg. The limitations on rea

• REFUELING ensure that: i (1) the-reactor will remain subcr l 1 g CORE ALTERATIONS and (2) a

$5 0 uniform boron concentration is mai volume having direct access

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e reactor ve r reactivity control in the water These limitations are l

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j consistent with the in conditions assumed for oron dilution incident  !

in the safety an s. The value of 0.95 or less for k,ff cludes a i 1% Ak/k ervative allowance for uncertainties. Similarly, the c ration value of 2000 ppm or greater includes a conservative uncer allowance of 50 ppm boron. '  !

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3/4.9.2 INSTRUMENTATION l1 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. i i 3/4.9.3 DECAY TIME The minimum requirement for . reactor subcriticality prior to movement of irradiated fuel assemblies in the reactor vessel ensures that sufficient i time has elapsed to allow the radioactive decay of the short-lived fission s

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products. This decay time is consistent with the assumptions used in the )

l safety analyses. '

i 3/4.9.4 CONTAINMENT BUILDING PENETRATIONS 1

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

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3/4.9.5 COMUNICATIONS _

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

3/4.9.6 REFUELING MACHINE -

The OPERABILITY requirements for the refueling machine ensure that:

(1) refueling machine will be used for movement of drive rods and fuel assem-blies, (2) each hoist has sufficient load capacity to lift a drive rod or fuel

' assembly, and (3) the core internals and reactor vessel are protected from excessive lifting force in the event they are inadvertently engaged during lifting operations.

1 SEABROOK - UNIT l' B 3/4 9-1 k 9509250282 950920 PDR l VELD gn P

ADOCK 05000443

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IV. RETYPE OF PROPOSED CHANGES I

See attached retype of proposed changes to Technical Specifications Bases. The attached retype reflects the currently issued version of Technical Specifications. Pending Technical Specification changes or Technical Specification changes issued subsequent to this submittal are not reflected in the enclosed retype. The enclosed retype should be checked for continuity with Technical Specifications prior to issuance.

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

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B 3,9. REFUELING OPERATIONS B 3.9.1 Boron Concentration The limit on the boron concentrations of the Reactor Coolant System (RCS) the refueling canal and the refueling cavity .

during refueling ensures that the reactor remains  :

subcritical during MODE 6. Refueling boron concentration is the soluble boron concentration in the coolant in each of these volumes having direct access to the reactor core during refueling.

The soluble boron concentration offsets the core reactivity and is measured by chemical analysis of a representative sample of the coolant in each of the volumes. Plant procedures ensure the specified boron concentration in order to maintain an overall core reactivity of k,rr s 0.95 during fuel handling, with control rods and fuel assemblies assumed to be in the most adverse configuration (least negative reactivity) allowed by plant procedures.

GDC 26 of 10 CFR 50, Appendix A. requires that two independent reactivity control systems of different design principles be provided. One of these systems must be ,

capable of holding the reactor core subcritical under cold conditions. The Chemical and Volume Control System (CVCS) is the system capable of maintaining the reactor subcritical in cold conditions by maintaining the boron concentration.

The reactor is brought to shutdown conditions before beginning operations to open the reactor vessel for refueling. After the RCS is cooled and depressurized and  ;

the vessel head is unbolted, the head is slowly removed to  :

form the refueling cavity. The refueling canal and the ,

refueling cavity are then flooded with borated water from the refueling water storage tank through the open reactor vessel by gravity feeding or by the use of the Residual Heat Removal (RHR) System pumps.

The pumping action of the RHR System in the RCS and the l natural circulation due to thermal driving heads in the reactor vessel and refueling cavity mix the added concentrated boric acid with the water in the refueling 3.9-1

s  ;

canal. The RHR System is in operation during refueling (see LC0 3.9.8.1, " Residual Heat Removal (RHR) and Coolant '

l Circulation-High Water Level," and LC0 3.9.8.2, " Residual l Heat Removal (RHR) and Coolant Circulation-Low Water )

level") to provide forced circulation in the RCS and assist  !

. in maintaining the boron concentrations in the RCS. the-

. refueling canal, and the refueling' cavity above the COLR limit,  ;

i During refueling operations, the reactivity condition of _the core is consistent with the initial conditions assumed for the boron dilution accident in the accident analysis and is  ;

. conservative for MODE 6. The boron concentration limit j 3

specified is-based on the core reactivity at the bsginr.ing of each fuel cycle (the end of refueling) and includes an i

uncertainty allowance.

l' The required boron concentration and the plant refueling procedures that verify the correct fuel loading plan (including full core mapping) ensure that the km of the  :

core will remain s 0.95 during the refueling operation. '

Hence, at least a 5% ak/k margin of safety is established l during refueling.

During refueling. the water volume in the spent fuel pool, the transfer canal, the refueling canal, the refueling

~ cavity, and the reactor vessel form a single mass. As a

result, the soluble boron concentration is relatively the j same in each of these volumes.

Continuation of CORE ALTERATIONS or positive reactivity

! additions (including actions to reduce boron concentration) ,

! is contingent upon maintaining the unit in compliance with the LCO.

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Transferring water to the RCS, refueling cavity, refueling canal, transfer canal or spent fuel pool that is lower in L boron concentration is acceptable provided that the boron -

concentration is greater than the refueling boron concentration requirement. Likewise, transferring water to

the RCS, refueling cavity, refueling canal. transfer canal '

or spent fuel pool that is lower in temperature (down to the operability requirements of the RWST in MODE 6: 50 DEG F) i- than the water contained in those volumes is also acceptable. These minimum requirements for boron 3.9-2 ,

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• Q concentration and water temperature are also applicable to ,

other MODE 6 Technical Specification ACTIONS that limit operations involving positive reactivity additions to ensure that the reactor remains subcritical and an adequate ,

shutdown margin is maintained. .!

N Suspension of CORE ALTERATIONS and positive reactivity  :

additions shall not preclude moving a' component to a safe  !

position. In addition to immediately suspending CORE ALTERATIONS or positive reactivity additions, boration to i restore the concentration must be initiated immediately. l In determining the required combination of boration flow  !

rate and concentration, no unique Design Basis Event must be l satisfied. The only requirement is to restore the boron {

concentration to its required value as soon as possible. In  !

order to raise the boron concentration as soon as possible, the operator should begin boration with the best source  ;

available for unit conditions. ,

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Once actions have been initiated, they must be continued  !

until the boron concentration is restored. The restoration time depends on the amount of boron that must be injected to 1 reach the required concentration.

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r 3.9-3