ML20080C221
| ML20080C221 | |
| Person / Time | |
|---|---|
| Site: | McGuire, Mcguire  |
| Issue date: | 12/02/1994 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20080C225 | List: |
| References | |
| NUDOCS 9412080134 | |
| Download: ML20080C221 (1) | |
Text
4 3/4.9 REFUELING OPERATf0NS U
BASES 3/4.9.1 BORON CONCENTRATION The limitations on reactivity conditions during REFUELING :nsure that:
(1) the reactor will remain subcritical during CORE ALTERATIONS, and (2) a uniform boron concentration is maintained for reactivity control in the water volume having direct access to the reactor vessel. These limitations are con-sistent with the initial ccnditions assumed for the boron dilution incident in the accident analyses. The value of 0.95 or less for K, includes a 1% delta g
k/k conservative allowance for uncertainties.
Similarly, the minimum boron concentration value specified in the Core Operating Limits Report or greater includes a conservative uncertainty allowance of 50 ppm boron.
The Reactor Makeup Water Supply to the Chemical and Volume Control (NV) System is normally isolated during refueling to prevent diluting the Reactor Coolant System boron concentration.
Isolation is normally accomplished by closing valve NV-250.
However, isolation may be accomplished by closing valves NV-131, NV-140, NV-176, NV-468, NV-808, and either NV-132 or NV-1026, when it is neces-sary to makeup water to the Refueling Water Storage Tank during refueling operations.
3/4.9.2 INSTRUMENTATION 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.
In MODE 6 the Wide Range Neutron Flux Detectors (ENC) can be used as Source Range Neutron Flux Monitors. All of the LCO, ACTION, and SURVEILLANCE REQUIREMENTS of 3/4.9.2 must be met for the two Source Range Neutron Flux Monitors that are in use at any time.
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 time has elapsed to allow the radioactive decay of the short-lived fission products.
This decay time is consistent with the assumptions usea in the accident analyses.
3/_L9.4 CONTAINMENT BUILDING PENETRATIONS The requirements on containment building penetration closure and OPERABILITY of the Reactor Building Containment Purge Exhaust System HEPA filters and charcoal adsorbers ensure that a release of radioactive material within containment will be restricted from leakage to the environment or fil-tered through the HEPA filters and charcoal adsorbers prior to discharge to the atmosphere. 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. Operation of the Reactor Building Containment Purge Exhaust System HEPA filters and charcoal adsorbers and the resulting iodine removal capacity are consistent with the assumptions of the accident analysis.
The methyl iodide penetration test cri-teria for the carbon samples have been made more restrictive than required for the assumed iodine removal in the accident analysis bece" the humidity to be seen by the charcoal adsorbers may be greater than 70% une lormal operating conditions.
McGUIRE - UNITS 1 AND 2 B 3/4 9-1 Amendment No. 149 (Unit 1)
Amendment No. 131 (Unit 2) 9412080134 941202 PDR ADOCK 05000369 Revised by NRC letter dated P
PDR December 2, 1994 - Bases Change Only