ML20196G181
| ML20196G181 | |
| Person / Time | |
|---|---|
| Site: | Calvert Cliffs  |
| Issue date: | 02/25/1988 |
| From: | BALTIMORE GAS & ELECTRIC CO. |
| To: | |
| Shared Package | |
| ML20196F103 | List: |
| References | |
| NUDOCS 8803070066 | |
| Download: ML20196G181 (1) | |
Text
.
r O
REACTIVITY CONTROL SYSTEMS BASES 0
The boron capability required below 200 F is based upon providing a 0
0 3% A k/k SHUTDOWN MARGIN after xenon decay and cooldown from 200 F to 140 F.
This condition requires either 737 gallons of 7.25% boric acid solution from the boric acid tanks or 9,844 gallons of 2300 ppm borated water from the refueling water tank.
The OPERABILITY of one boron injection system during REFUELING ensures that this system is available for reactivity control while in MODE 6.
3/4.1.3 MOVABLE CONTROL ASSEMBLIES The specifications of this section ensure that (1) acceptable power distribution limits are maintained, (2) the required SHUTDOWN MARGIN at critical conditions (MODES 1 and 2 (Keff 2 1.0)) is maintained, and (3) the potential effects of a CEA ejection accident are limited to acceptable levels.
SHUTDOWN MARGIN requirements for critical conditions vary throughout the cycle as a function of fuel depletion, RCS boron concentrations, and power level. These requirements are satisfied via adherence to the Technical Specifications of Section 3/4.1.3 which specify the appropriate operability status and position of the full length CEAs. Cycle specific calculations are performed to verify that the restrictions of Section 3/4.1.3, in particular, the Transient Insertion Limits of Technical Specification 3.1.3.6, yield appropriate SHUTDOWN MARGINS.
The most limiting SHUTDOWN MARGIN requirements for Modes 1 and 2 (Keff 21.0) conditions at beginning of cycle are determined by the requirements of several transients, e.g., Loss of Flow, Seized Rotor, etc.
However, the most limiting SHUTDOWN MARGIN requirements for these same modes at end of cycle come from just one transient, the Steam Line Rupture.
The requirements of the Steam Line Rupture event at end of cycle for both the full power and no load conditions are significantly larger than those of any other event at that time in cycle and, also, considerably larger than the most limiting requirements at beginning of cycle.
Although the most limiting SHUTDOWN MARGIN requirements at end of cycle are much larger than those at beginning of cycle, the available SHUTDOWN MARGINS retained via the scramming of the CEAs is also substantially larger at end of cycle due to the much lower boron concentration.
To verify that adequate SHUTDOWN MARGINS are available throughout the cycle to satisfy the f
changing requirements, calculations are performed at both beginning and end of l
cycle.
It has been determined that calculations at these two times in cycle are sufficient since the available SHUTDOWN MARGINS increase throughout the cycle at a faster rate than the most limiting SHUTDOWN MARGIN requirements.
$$N00$ 0 k7 P
l CALVERT CLIFFS - UNIT 1 B 3/4 1-3 Amendment No. JJ///E//JpE, I