ML20239A644
| ML20239A644 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 09/10/1987 |
| From: | NORTHEAST NUCLEAR ENERGY CO. |
| To: | |
| Shared Package | |
| ML20239A645 | List: |
| References | |
| NUDOCS 8709180048 | |
| Download: ML20239A644 (1) | |
Text
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3/4.4 REACTOR COOLANT SYSTEM BASES l
3/4.4.1 REACTOR COOLANT LOOPS AND COOLANT CIRCULATION 1
The plant is designed to operate in MODES 1 and 2 with three or four reactor coolant loops in operation and maintain DNBR above 1.30 during all normal operations and anticipated transients.
With less than the required i
reactor coolant loops in operation this specification requires that the' plant-be in at least HOT STANDBY within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />.
I In MODE 3 and 4, two reactor coolant loops provide sufficient heat removal capability for removing core decay heat even in the event of a bank withdrawal accident; however, a single reactor coolant loop provides sufficient heat re-moval capacity if a' bank withdrawal accident can be prevented, i.e., by opening 4
the Reactor Trip System breakers.
Single failure considerations require that two loops be OPERABLE at all times.
In MODE 4, and in MODE 5 with reactor coolant loops filled, a single i
reactor coolant loop or RHR loop provides sufficient heat removal capability for removing decay heat; but single failure considerations require that at l
least two loops (either RHR or RCS) be OPERABLE.
l In MODE 5 with reactor coolant loops not filled, a single RHR loop provides sufficient heat removal capability for. removing decay heat; but single failure i
considerations, and the unavailability of the steam generators as a heat i
removing component, require that at least two RHR loops be' OPERABLE.
The operation of one reactor coolant pump (RCP) or one RHR pump provides adequate flow to ensure mixing, prevent stratification and produce gradual reactivity changes during boron concentration reductions in the Reactor Coolant System.
The reactivity change rate associated with boron reduction will, therefore, be within the capability of operator recognition and control.
The restrictions on starting an RCP with one or more RCS cold legs less than or equal to 350 F are provided to prevent RCS pressure transients, caused by energy additions from the Secondary Coolant System, which could exceed the limits of Appendix G to 10 CFR Part 50.
The RCS will be protected against overpressure transients and will not exceed the limits of Appendix G by either:
(1) restricting the water volume in the pressurizer and thereby providing a volume for the reactor coolant to expand into, or (2) by restricting starting of the RCPs to when the secondary water temperature of each steam generator is less than 50 F above each of the RCS cold leg temperatures.
The requirement to maintain the isolated loop stop valves shut with' power removed ensures that no reactivity addition to the core could occur due to the 1
startup of an isolated loop.
Verification of the boron concentration in an j
idle loop prior to opening the stop valves provides a reassurant.e of the l
adequacy.of the boron concentration in the isolated loop.
Draining and refilling
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the isolated loop within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> prior to opening its stop valves ensures adequate mixing of the coolant in this loop and prevents any reactivity effects due to boron concentration stratifications.
8709180048 B70910 PDR ADOCK 05000423 p
PDR MILLSTONE
. UNIT 3 B 3/4 4-1 Amendment No. 7 j
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