ML060060116

Enclosure, Technical Specifications, Amd MC5109, Standby Liquid Control System

ML060060116
Person / Time
Site:	Hatch
Issue date:	01/05/2006
From:	Plant Licensing Branch III-2
To:
Gratton C, NRR/DLPM, 415-1055
Shared Package
ML052870353	List: ML052870246 ML060060116
References
Download: ML060060116 (6)

Text

SLC System 3.1.7 SPB Solution Volume vs. Concentration Requirements is 9

.5 vC I

p.

0 i

0 S

sI I I I I i X I -L- 1 ,I I I I I I=

1000 1200 1400160 0180 200 2200 2400 200 280 300D0 3 3400 3684000 4200 4400 46004800 Gross Volume of Solution Tank (gal)

Figure 3.1.7-1 (page 1 of 1)

Sodium Pentaborate Solution Volume Versus Concentration Requirements HATCH UNIT 1 3.1 -20 Amendment No. 24 7

SLC System 3.1.7 OF (l/%.120F)

U.

0 Concentration (Weight Percent Sodium Pentaborate in Solution)

Figure 3.1.7-2 (page 1 of 1)

Sodium Pentaborate Solution Temperature Versus Concentration Requirements HATCH UNIT 1 3.1-21 Amendment No. 247

SLC System B 3.1.7 B 3.1 REACTIVITY CONTROL SYSTEMS B3.1.7 Standby Liquid Control (SLC) System BASES BACKGROUND The SLC System Is designed to provide the capability of bringing the reactor, at any time In a fuel cycle, from full power and minimum control rod inventory (which Is at the peak of the xenon transient) to a subcritical condition with the reactor in the most reactive, xenon free state without taking credit for control rod movement. The SLC System satisfies the requirements of 10 CFR 50.62 (Ref. 1) on anticipated transient without scram.

The SLC System consists of a sodium pentaborate solution storage tank, two positive displacement pumps, two explosive valves that are provided Inparallel for redundancy, and associated piping and valves used to transfer borated water from the storage tank to the reactor pressure vessel (RPV). The borated solution is discharged near the bottom of the core shroud, where it then mixes with the cooling water rising through the core. A smaller tank containing demineralized water is provided for testing purposes.

APPLICABLE The SLC System Is manually Initiated from the main control room, SAFETY ANALYSES as directed by the emergency operating procedures, If the operator believes the reactor cannot be shut down, or kept shut down, with the control rods. The SLC System is used in the event that enough control rods cannot be Inserted to accomplish shutdown and cooldown inthe normal manner. The SLC System Injects borated water Into the reactor core to add negative reactivity to compensate for all of the various reactivity effects that could occur during plant operations. To meet this objective, it Is necessary to inject a quantity of boron, which produces a concentration of 800 ppm of natural boron equivalent, In I the reactor coolant at 700F. To allow for potential leakage and imperfect mixing Inthe reactor system, an amount of boron equal to 25% of the amount cited above Is added (Ref. 2). The Region A volume versus concentration limits in Figure 3.1.7-1 and the Region A temperature versus concentration limits in Figure 3.1.7-2 are calculatessuch that the required concentration Is achieved accounting for dilutiop in the RPV with high water level and including the water volume irn the residual heat removal shutdown cooling piping and in the recirculation loop piping. This quantity of borated solution is the amount that Is above the pump suction shutoff level Inthe boron solution storage tank. No credit is taken for the portion of the tank volume that cannot be injected.

(continued)

HATCH UNIT 1 B 3.1-34 Amendment No. 247

SLC System 3.1.7 SPB Solution Volume vs. Concentration Requirements C

0 S

.5 0

co 0

M a.

M 0

I ae Gross Volume of Solution Tank (Sal)

Figure 3.1.7-1 (page 1 of 1)

Sodium Pentaborate Solution Volume Versus Concentration Requirements HATCH UNIT 2 3.1 -20 Amendment No. 191

SLC System 3.1.7 e

E A

0 5 10 15 20 25 Concentration (Weight Percent Sodium Pentaborate In Solution)

Figure 3.1.7-2 (page 1 of 1)

Sodium Pentaborate Solution Temperature Versus Concentration Requirements HATCH UNIT 2 3.1-21 Amendment No. 191

SLC System B 3;1.7 B 3.1 REACTIVITY CONTROL SYSTEMS B 3.1.7 Standby Liquid Control (SLC) System BASES BACKGROUND The SLC System Is designed to provide the capability of bringing the reactor, at any time in a fuel cycle, from full power and minimum control rod inventory (which Is at the peak of the xenon transient) to a subcritical condition with the reactor in the most reactive, xenon free state without taking credit for control rod movement. The SLC System satisfies the requirements of 10 CFR 50.62 (Ref. 1) on anticipated transient without scram.

The SLC System consists of a sodium pentaborate solution storage tank, two positive displacement pumps, two explosive valves that are provided in parallel for redundancy, and associated piping and valves used to transfer borated water from the storage tank to the reactor pressure vessel (RPV). The borated solution is discharged near the bottom of the core shroud, where It then mixes with the cooling water rising through the core. A smaller tank containing demineralized water Is provided for testing purposes.

APPLICABLE The SLC System Is manually Initiated from the main control room, SAFETY ANAYSES as directed by the emergency operating procedures, if the operator believes the reactor cannot be shut down, or kept shut down, with the control rods. The SLC System Is used inthe event that enough control rods cannot be Inserted to accomplish shutdown and cooldown In the normal manner. The SLC System Injects borated water Into the reactor core to add negative reactivity to compensate for all of the various reactivity effects that could occur during plant operations. To meet this objective, It Is necessary to Inject a quantity of boron, which produces a concentration of 800 ppm of natural boron equivalent, in I the reactor coolant at 700F. To allow for potential leakage and imperfect mixing Inthe reactor system, an amount of boron equal to 25% of the amount cited above Is added (Ref. 2). The Region A volume versus concentration limits in Figure 3.1.7-1 and the Region A temperature versus concentration limits in Figure 3.1.7-2 are calculated such that the required concentration Is achieved accounting for dilution in the RPV with high water level and including the water volume Inthe residual heat removal shutdown cooling piping and in the recirculation loop piping. This quantity of borated solution is the amount that is above the pump suction shutoff level In the boron solution storage tank. No credit is taken for the portion of the tank volume that cannot be injected.

(continued)

HATCH UNIT 2 B 3.1-34 Amendment No. 191