ML052550158
| ML052550158 | |
| Person / Time | |
|---|---|
| Site: | Mcguire, Catawba, McGuire  |
| Issue date: | 09/01/2005 |
| From: | NRC/NRR/DLPM |
| To: | |
| Peters S, NRR/DLPM, 415-1842 | |
| Shared Package | |
| ML05210075 | List: |
| References | |
| TAC MC7545, TAC MC7546, TAC MC7547, TAC MC7548 | |
| Download: ML052550158 (10) | |
Text
Boron Concentration 3.9.1 3.9 REFUELING OPERATIONS 3.9.1 Boron Concentration LCO 3.9.1 Boron concentrations of the Reactor Coolant System, the refueling canal, and the refueling cavity shall be maintained within the limit specified in the COLR.
NOTE --- cav h
Only applicable to the refueling canal and refueling cavity when connected to the RCS.
APPLICABILITY:
MODE 6.
ACTIONS CONDITION REQUIRED ACTION COMPLETION TIME A.
Boron concentration not A.1 Suspend CORE Immediately within limit.
ALTERATIONS.
AND A.2 Suspend positive reactivity Immediately additions.
AND A.3 Initiate action to restore Immediately boron concentration to within limit.
SURVEILLANCE REQUIREMENTS SURVEILLANCE FREQUENCY SR 3.9.1.1 Verify boron concentration is within the limit specified In COLR.
72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> McGuire Units I and 2 3.9.1-1 Amendment Nos. 231/213
Boron Concentration B 3.9.1 B 3.9 REFUELING OPERATIONS B 3.9.1 Boron Concentration BASES BACKGROUND 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. The refueling boron concentration limit is specified in the COLR. Plant procedures ensure the specified boron concentration In order to maintain an overall core reactivity of kff~g 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 (Ref. 1). 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 by one of the following methods:
- 1.
gravity fill directly from the refueling water storage tank (RWST),
- 2.
refueling water pump taking suction directly from RWST,
- 3.
refueling water pump taking suction from the spent fuel cooling water purification loop, or
- 4.
RHR pumps taking suction from the RWST.
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 McGuire Units I and 2 B 3.9.1 -1 Revision No. 68
Boron Concentration B 3.9.1 BASES BACKGROUND (continued) cavity mix the added concentrated boric acid with the water in the refueling canal. The RHR System Is in operation during refueling (see LCO 3.9.5, "Residual Heat Removal (RHR) and Coolant Circulation-High Water Level," and LCO 3.9.6, "Residual 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.
APPLICABLE SAFETY ANALYSES 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 specified in the COLR is based on the core reactivity at the beginning of each 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 kef of the core will remain
- 0.95 during the refueling operation.
Hence, at least a 5% Ak/k margin of safety is established 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 same in each of these volumes.
The RCS boron concentration satisfies Criterion 2 of 10 CFR 50.36 (Ref.
2).
LCO The LCO requires that a minimum boron concentration be maintained In the RCS, the refueling canal, and the refueling cavity while in MODE 6.
The boron concentration limit specified in the COLR ensures that a core ken of
- 0.95 Is maintained during fuel handling operations. 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 subcritical. The required boron concentration ensures a kefs 0.95. Above MODE 6, LCO 3.1.1, "SHUTDOWN MARGIN (SDM),' ensure that an adequate amount of negative reactivity is available to shut down the reactor and maintain it subcritical.
The Applicability Is modified by a Note. The Note states that the limits on boron concentration are only applicable to the refueling canal and the McGuire Units 1 and 2 B 3.9.1-2 Revision No. 68
Boron Concentration B 3.9.1 BASES refueling cavity when those volumes are connected to the Reactor Coolant System. When the refueling canal and the refueling cavity are isolated from the RCS, no potential path for boron dilution of the RCS exists.
"Refueling cavity" includes the shallow and deep end of the refueling cavity. "Refueling canal" is the fuel transfer canal in the Reactor Building.
"Connected" is when the water in the reactor vessel and the refueling cavity is hydraulically connected.
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 concentration of any coolant volume in the RCS, the refueling canal, or the refueling cavity 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. Operations that individually add limited positive reactivity (e.g., temperature fluctuations from Inventory addition or temperature control fluctuations),
but when combined with all other operations affecting core reactivity (e.g.,
Intentional boration) result in overall net negative reactivity addition, are not precluded by this action.
A.3 In addition to immediately suspending CORE ALTERATIONS and 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. An acceptable method is to borate at greater than or equal to 30 gpm of a solution containing greater than or equal to 7000 ppm boron or Its equivalent.
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.
McGuire Units I and 2 B 3.9.1-3 Revision No. 68
Boron Concentration B 3.9.1 BASES SURVEILLANCE SR 3.9.1.1 REQUIREMENTS This SR ensures that the coolant boron concentration in the RCS, and connected portions of the refueling canal and the refueling cavity, Is within the COLR limits. The boron concentration of the coolant in each required volume is determined periodically by chemical analysis. Prior to re-connecting portions of the refueling canal or the refueling cavity to the RCS, this SR must be met per SR 3.0.4. If any dilution activity has occurred while the cavity or canal were disconnected from the RCS, this SR ensures the correct boron concentration prior to communication with the RCS. One sample from the refueling canal or refueling cavity is sufficient to determine the boron concentration in that volume of water.
An additional sample Is taken from the RCS.
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.
REFERENCES
- 1.
10 CFR 50, Appendix A, GDC 26.
- 2.
10 CFR 50.36, Technical Specifications, (c)(2)(ii).
McGuire Units I and 2 B 3.9.1-4 Revision No. 6 8
Boron Concentration 3.9.1 3.9 REFUELING OPERATIONS 3.9.1 Boron Concentration LCO 3.9.1 Boron concentrations of the Reactor Coolant System, the refueling canal, and the refueling cavity shall be maintained within the limit specified in the COLR.
OTE-Only applicable to the refueling canal and refueling cavity when connected to the RCS.
APPLICABILITY:
MODE 6.
ACTIONS CONDITION REQUIRED ACTION COMPLETION TIME A.
Boron concentration not A.1 Suspend CORE Immediately within limit.
ALTERATIONS.
AND A.2 Suspend positive reactivity Immediately additions.
AND A.3 Initiate action to restore Immediately boron concentration to within limit.
SURVEILLANCE REQUIREMENTS SURVEILLANCE FREQUENCY SR 3.9.1.1 Verify boron concentration Is within the limit specified in 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> COLR.
Catawba Units I and 2 3.9.1-1 Amendment Nos. 226/221
Boron Concentration B 3.9.1 B 3.9 REFUELING OPERATIONS B 3.9.1 Boron Concentration BASES BACKGROUND 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. The refueling boron concentration limit is specified in the COLR. Plant procedures ensure the specified boron concentration In order to maintain an overall core reactivity of kffs 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 (Ref. 1). 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 to approximately 75 percent of Its required level and then using the refueling water pump to complete the filling process or by the use of the Residual Heat Removal (RHR) System pumps.
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 cavity mix the added concentrated boric acid with the water in the refueling canal. The RHR System Is In operation during refueling (see LCO 3.9.4, "Residual Heat Removal (RHR) and Coolant Circulation-High Water Level," and LCO 3.9.5, "Residual 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.
Catawba Units 1 and 2 B 3.9.1 -1 Revision No. 1
Boron Concentration B 3.9.1 BASES APPLICABLE SAFETY ANALYSES 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 specified in the COLR is based on the core reactivity at the beginning of each 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 keff of the core will remain *0.95 during the refueling operation.
Hence, at least a 5% iAklk margin of safety is established 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 same in each of these volumes.
The RCS boron concentration satisfies Criterion 2 of 10 CFR 50.36 (Ref.
2).
LCO The LCO requires that a minimum boron concentration be maintained in the RCS, the refueling canal, and the refueling cavity while in MODE 6.
The boron concentration limit specified In the COLR ensures that a core kcff of
- 0.95 Is maintained during fuel handling operations. 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 subcritical. The required boron concentration ensures a ken < 0.95. Above MODE 6, LCO 3.1.1, "SHUTDOWN MARGIN (SDM),"
ensures that an adequate amount of negative reactivity is available to shut down the reactor and maintain It subcritical.
The Applicability is modified by a Note. The Note states that the limits on boron concentration are only applicable to the refueling canal and the refueling cavity when those volumes are connected to the Reactor Coolant System. When the refueling canal and the refueling cavity are isolated from the RCS, no potential path for boron dilution of the RCS exists.
"Refueling cavity' includes the shallow and deep end of the refueling cavity. "Refueling canal" Is the fuel transfer canal In the Reactor Building.
"Connected" is when the water in the reactor vessel and the refueling cavity Is hydraulically connected.
Catawba Units 1 and 2 B 3.9.1-2 Revision No. 2
Boron Concentration B 3.9.1 BASES ACTIONS A.1 and A2 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 concentration of any coolant volume in the RCS, the refueling canal, or the refueling cavity 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. Operations that individually add limited positive reactivity (e.g., temperature fluctuations from inventory addition or temperature control fluctuations),
but when combined with all other operations affecting core reactivity (e.g.,
intentional boration) result in overall net negative reactivity addition, are not precluded by this Action.
A.3 In addition to immediately suspending CORE ALTERATIONS and 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. An acceptable method is to borate at greater than or equal to 30 gpm of a solution containing greater than or equal to 7000 ppm boron or Its equivalent.
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 RCS, and connected portions of the refueling canal and the refueling cavity, is within the COLR limits. The boron concentration of the coolant in each required volume is determined periodically by chemical analysis. Prior to re-connecting portions of the refueling canal or the refueling cavity to the RCS, this SR must be met per SR 3.0.4. If any dilution activity has Catawba Units I and 2 B 3.9.1-3 Revision No. 2
Boron Concentration B 3.9.1 BASES SURVEILLANCE REQUIREMENTS (continued) occurred while the cavity or canal were disconnected from the RCS, this SR ensures the correct boron concentration prior to communication with the RCS. One sample from the refueling canal or reactor cavity Is sufficient to determine the boron concentration In that volume of water.
An additional sample Is taken from the RCS.
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.
REFERENCES
- 1.
10 CFR 50, Appendix A, GDC 26.
- 2.
10 CFR 50.36, Technical Specifications (c)(2)(ii).
Catawba Units I and 2 B 3.9.14 Revision No. 0