ML20195C519

Proposed Tech Specs Sections 3.9.1,revised to Maintain CTS Requirements on Refueling Pool Boron Concentration Limits & 5.6.5,revised to Delete Item 5.6.5.a

ML20195C519
Person / Time
Site:	Callaway
Issue date:	05/28/1999
From:	UNION ELECTRIC CO.
To:
Shared Package
ML20195C516	List: ML20195C513 ML20195C519
References
NUDOCS 9906080207
Download: ML20195C519 (7)

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Attachment to ULNRC-4043

1. a REVISED IMPROVED TECHNICAL SPECIFCATION PAGES 3.9-1 (ULNRC-4043, dated 5/28/99) 3.9.2 B 3.9.1-1 B 3.9.1-2 B 3.9.1-3 B 3.9.1-4 5.0-29 (ULNRC-4044, dated 5/27/99) 5.0-31 l

9906080207 990528 PDR ADOCK 05000483' P PDR ,

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Boron Concentrttion s

3.9.1 3.9 REFUELING OPERATIONS 3.9.1 Boron Concentration LCO 3.9.1 Boron concentrations of all filled portions of the Reactor Coolant System and the refueling pool that have direct access to the reactor vessel, shall be maintained sufficient to ensure that the more restrictive of the following reactivity conditions is met: ,

a. A k, s 0.95, or

b. A boron concentration of a 2000 ppm.

APPLICABILITY: MODE 6.

NOTE While this LCO is not met, entry into MODE 6 from MODE 5 is not permitted.

ACTIONS CONDITION REQUIRED ACTION COM ON A. Boron concentration not A.1 Suspend CORE Immediately within limit. ALTERATIONS.

M A.2 Suspend positive immediately reactivity additions.

M A.3 initiate action to restore immediately boron concentration to within limit.

CALLAWAY PLANT 3.9-1 Amendment No.133

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Boron Concentretion

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3.9.1 I

. SURVEILLANCE REQUIREMENTS SUP'IEILLANCE FREQUENCY SR 3.9.1.1 Verify boron concentration is within the limit. 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> )

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l CALLAWAY PLANT 3.9-2 Amendment No.133

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Boron Concentration B 3.9.1 B 3.9 REFUELING OPERATIONS B 3.9.1 Boron Concentration BASES BACKGROUND The limit on the boron concentration of filled portions of the Reactor Coolant System (RCS) and the refueling pool that have direct access to the reactor vessel 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. The refueling boron concentration is sufficient to maintain Shutdown Margin (SDM) with the most adverse conditions of fuel assembly and control rod position allowed by plant procedures. The .

boron concentration that is maintained in MODE 6 is sufficient to maintain k, s 0.95 with the most reactive rod control cluster assembly completely removed from its fuel assembly. )

i GDC 26 of 10 CFR 50, Appendix A, requires that two independent reactivity control systems of different design principles be provided (Ref.1). One of these systems must be capable of holding the reactor 3 core suberitical under cold conditions. The Chemical and Volume Control System (CVCS) is the main system capable of maintaining the reactor suberitical 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 cavity is then flooded to form the refueling pool. Typically, the refueling pool is flooded with borated w~ater from the refueling water storage tank through the open reactor vessel by the use of the Residual Heat Removal (RHR) System pumps or gravity feeding.

The pumping action of the RHR System in the RCS and the natural circulation due to thermal driving heads in the reactor vessel and refueling pool mix the added concentrated boric acid with the water in the refueling pool. The RHR System is in operation during refueling (see LCO 3.9.5,

" Residual Heat Removal (RHR) and Coolant Circulation - High Water (continued)

CALLAWAY PLANT B 3.9.1-1 Revision O

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Boron Concantration B 3.9.1 '

, BASES-

' BACKGROUND Level," and LCO 3.9.6, " Residual Heat Removal (RHR) and Coolant (continued) Circulation - . Low Water Level") to provide forced circulation in the RCS and assist in maintaining uniform boron concentrations in the RCS and the refueling pool above the LCO limits. Administrative controls will limit the volume of unborated water that can be added to the refueling pool for decontamination activities in order to prevent diluting the refueling pool below the specified limits (Ref. 3).

APPLICABLE The boron concentration limit specified in the COLR, and consistent with SAFETY the LCO limits, is based on the core reactivity at the beginning of each ANALYSES fuel cycle (the end of refueling) and includes an uncertainty allowance.

The required boron concentration and the plant refueling procedures that verify the correct fuel loading plan (including full core mapping) ensure that the k,, of the core will remain s 0.95 during the refueling operation.

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

Safety analyses assume a B-10 abundance of 19.9 atom % (Ref. 4).

Administrative controls ensure that the reactivity insertion from the reactor coolant system and the refueling pool reflects this assumption.

During refueling, the water volume in the refueling pool and the reactor vessel form a single mass. As a result, the soluble boron concentration is relatively the same in each of these volumes having direct access to the reactor vessel. a l

The limiting boron dilution accident analyzed occurs in MODE 5 (Ref. 2).

Boron dilution accidents are precluded in MODE 6 by isolating potential dilution flow paths. See LCO 3.9.2,"Unborated Water Source Isolation Valves." Unacceptable dilution from refueling pool decontamination activities is precluded by the following (Ref. 3):

1. The maximum allowable amount of unborated reactor makeup water that may be added to the refueling pool for decontamination activities is calculated for each refueling and will not cause the refueling pool boron concentration to fall below the LCO limits.

This maximum allowable volume it based on initial pool boron concentration and one-half the RCS volume at mid-loop.  ;

2. The refueling pool is drained to approximately one foot above the reactor cavity seal / shield ring. The refueling pool is then drained (continued)

CALLAWAY PLANT B 3.9.1-2 Revision O

.' o Boron Conc 9ntration B 3.9.1

. BASES APPLICABLE via the reactor coolant drain tank pumps or other available means SAFETY (excluding the RHR system) until the level is below the seal / shield ANALYSES ring. This directs potentially diluted water at the top of the pool (continued) away from the reactor vessel and core.

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3. After the level has been lowered to below the cavity seal / shield ring, further draining of the area enclosed by the inside diameter of the ring is performed via the RHR connection to the Chemical and Volume Controlletdown line.

The RCS boron concentration satisfies Criterion 2 of 10 CFR 50.36(c)(2)(ii).

LCO The LCO requires that a minimum boron concentration be maintained in the filled portions of the RCS and the refueling pool, that have direct s access to the reactor vessel while in MODE 6. The baron concentration limit is specified in the COLR. The COLR limit ensures that a core k, of s 0.95 is maintained during fuel handling operations, and shall in all cases be 2 2000 ppm. Violation of the LCO could lead to an inadvertent criticality during MODE 6.

APPLICABILITY This LCO is applicable in MODE 6 to ensure that the fuel in the reactor vessel will remain suberitical. The required boron concentration ensures a k, s 0.95. Above MODE 6, LCO 3.1.1," SHUTDOWN MARGIN (SDM),

LCO 3.1.5, " Shutdown Bank Insertion Limits," and LCO 3.1.6," Control Bank Insertion Limits," ensure that an adequate amount of negative reactivity is available to shut down the reactor and maintain it suberitical.

The Applicability is modified by a Note stating that transition from MODE 5 to MODE 6 is not permitted while the LCO is not met. This Note specifies an exception to LCO 3.0.4 and prohibits the transition when boron concentration limits are not met. This Note assures that core reactivity is maintained within limits during fuel handling operations.

ACTIONS A.1 and A.2 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. If the boron (continued)

CALLAWAY PLANT B 3.9.1-3 Revision O

a Boron Concentration B 3.9.1 BASES ACTIONS A.1 and A.2 (continued) concentration of any coolant volume in the filled portions of the RCS and the refueling pool that have direct access to the reactor vessel, is less than its limit, all operations involving CORE ALTERATIONS or positive reactivity additions must be suspended immediately.

Suspension of CORE ALTERATIONS and positive reactivity additions shall not preclude moving a component to a safe position.

Al In addition to immediately suspending CORE ALTERATIONS or positive reactivity additions, boration to restore the concentration must be initiated immediately.

In determining the required combination of boration flow rate and concentration, no unique Design Basis Event must be 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.

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 reach the required concentration.

SURVEILLANCE SR 3.9.1.1 REQUIREMENTS .

This SR ensures that the coolant boron concentration in the filled portions of the RCS and the refueling pool that have direct access to the reactor vessel, is within the limit specified in the COLR and consistent with the LCO limits. The boron concentration of the coolant in each required volume is determined periodically by chemical analysis.

A minimum Frequency of once every 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> is a reasonable amount of time to verify the boron concentration of representative samples. The Frequency is based on operating experience, which has shown 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> to be adequate. l (continued)

CALLAWAY PLANT B 3.9.1-4 Revision O

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