ML19210D623
| ML19210D623 | |
| Person / Time | |
|---|---|
| Site: | Pilgrim |
| Issue date: | 11/21/1979 |
| From: | BOSTON EDISON CO. |
| To: | |
| Shared Package | |
| ML19210D614 | List: |
| References | |
| NUDOCS 7911270402 | |
| Download: ML19210D623 (2) | |
Text
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LIMITING CONDITIONS FOR OPERATION SURVEILLANCE REQUIREMENTS l
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2.
The SRM shall have a minimum of 3 cps with all rods fully inserted in the core.
C.
Spent Fuel Pool Water Level C. Spent Fuel Pool Water Level Whenever irradiated fuel is stored Whenever irradiated fuel is stored in the spent fuel pool, the pool in the spent fuel pool, the water water level shall be maintained at level shall be recorded daily, or above 33 feet.
I D.
Multiple Control Rod Remnval D. Multiple Control Rod Removal Any number of control rods and/
Within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> prior to the start of or control rod drive mechanisms removal of control rods and/or control may be removed from the reactor rod drive mechanisms from the reactor pressure vessel provided that at pressure vessel and at least once per least the following requirements 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> thereafter until all control are satisfied until all control rods are fully inserted in the core, rods and control rod drive mech-verify that:
anisms are reinstalled and all control rods are fully inserted in the core.
a.
The reactor mode switch is a.
The reactor mode switch is operable locked in the Refuel position and locked in the Refuel position I
per Specification 3.10.A, per Specification 3.10.A.
except that the Refuel posi-tion "one rod out" interlock may be bypassed, as required, for those control rods and/or control rod drive mechanisms i
to be removed, after the fuel assemblies have been removed as specified below.
b.
The source range monitors (SRM) b.
The SRM channels are operable per are operable per Specification Specification 3.3.B.4.
3.3.B.4.
s c.
The Reactivity Margin require-c.
The Reactivity Margin requirements ments of Specification 3.3.A.1 of Specification 3.3. A.1 are satisfied.
are satisfied.
d.
All other control rods are either fully inserted or have the surrounding four fuel assemblies removed.
e.
The four fuel assemblies are
}T99 0kb removed from the core cell
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surrounding each control rod or rod drive mechanism to be removed.
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3.10 BASES B.
Core Monitoring The SRM's are provided to monitor the core during periods of station shutdown and to guide the operator during refueling operations and station startup.
Requiring two operable SRM's in or adjacent to any core quadrant where fuel or control rods are being moved assures adequate monitoring of that quadrant during such alterations. The requirement of 3 counts per second provides assurance that neutron flux is being monitored sr.d insures that startup is conducted only if the source range flux level is above the minimum assumed in the control rod drop accident.
The limiting conditions for operation of the SRM subsystem of the Neutron Monitoring System are derived from the Station Nuclear Safety Operational Analysis (Appendix G) and a functional analysis of the neutron monitoring system. The specification is based on the Operational Nuclear Safety Re-quirements in subsection 7.5.10 of the Safety Analysis Report.
C.
Spent Fuel Pool Water Level To assure that there is adequate water to shield and cool the irradiated fuel assemblies stored in the pool, a minimum pool water level is established.
The minimum water level of 33 feet is established because it would be a significant change from the normal level (-1 foot) and is well above the level to assure adequate cooling.
D.
Multiple Control Rod Removal These specifications ensure that maintenance or repair of control rods or rod drives will be persormed under conditions that limit the probability of inadvertent criticality.
The requirement that the fuel assemblies in the cell controlled by the control rod be removed from the reactor core before the interlock can be bypassed e
insures that withdrawal of another control rod does not result in inadvertent criticality.
Each control rod essentially provides reactivity control for the fuel assemblies in the cell associated with the control rod. Thus, removel of an entire cell (fuel assemblies plus control rod) results in a lower reactivity potential of the core.
4.10 BASES A-Refueling Interlocks Complete functional testing of all refueling interlocks before any refueling outage will provide positive indication that the interlocks operate in the situations for which they were designed. By loading each hoist with a weight equal to the fuel assembly, positioning the refueling platform, and with-drawing control rods, the interlocks can be subjected to valid operational tests. Where redundancy is provided in the logic circuitry, tests can be performed to assure that each redundant logic element can independently perform its functions.
B.
Core Monitoring Requiring the SRM's to be functionally tested prior to any core alteration assures that the SRM's will be operable at the start of that alteration.
The daily response check of the SRM's ensures their continued operability.
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