ML20212M728
| ML20212M728 | |
| Person / Time | |
|---|---|
| Site: | Grand Gulf  |
| Issue date: | 08/15/1986 |
| From: | MISSISSIPPI POWER & LIGHT CO. |
| To: | |
| Shared Package | |
| ML20212M724 | List: |
| References | |
| TAC-61930, NUDOCS 8608270099 | |
| Download: ML20212M728 (5) | |
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1 GRAND Gi1F - LNIT 1 3A 4-3A AME? CENT lb.
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Percent of Rated Flow substled FIGURE 3.4.1.1-1 POWER -
FLOW OPERATING MAP c,.20-86 t
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l 3/4.4 REACTOR COOLANT SYSTEM E
BASES 3
D 3/4.4.1 RECIRCULATION SYSTEM 2=esar T R eiss %.4. I Operation with one reactor core coolant recirculation loop inoperable &
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1 An inoperable jet pump is not, in itself, a sufficient reason to declare a recirculation loop inoperable, but it does, in case of a design-basis-accident, increase the blowdown area and reduce the capability of reflooding the core; thus, the requirement for shutdown of the facility with a jet pump l
in:perable. Jet pump failure can be detected by monitoring jet pymp per-famance on a prescribed schedule for significant degradation.a #ecirculation 1 cop flow mismatch limits are in compliance with ECCS LOCA analysis design l
criteria.
The limits will ensure an adequate core flow coastdown from either i
recirculation loop following a LOCA 1
2vesar 'C' (' usa eseameaad -
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l In order to prevent undue stress on the vessel nozzles and bottom head I
region, the recirculation loop temperatures shall be within 50"F of each other l
prior to startup of an idle loop.
The loop temperature must also be within 50 F of the reactor pressure vessel coolant temperature to prevent thermal shock l
to the recirculation pump and recirculation nozzles. Since the coolant in the bottom of the vessel is at a lower temperature than the coolant in the upper l
regions of the core, undue stress on the vessel would result if the tamperature difference was greater than 100"F.
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The recirculation flow contro1~ valves provide regulation of individual 4
l recirculation loop drive flows; which, in turn, will vary the flow rate of coolant through the reactor core over a range consistent with the rod pattern and recirculation pump speed. The recirculation flow control system consists l
of the electronic anc hydraulic components necessary for the positioning of l
l the two hydraulically actuated flow control valves. Solid state control logic l
i trill generate a flow control valve " motion inhibit" signal in response to any ene of several hydraulic power unit or analog control circuit failure signals.
The " notion inhibit" signal causes hydraulic power unit shutdown and hydraulic isolation such that the flow control valve fails "as is." This design feature insures that the flow control valves do not respond to potentially erroneous j
csntrol signals.
Electronic limiters exist in the position control loop of each flow control valve to limit the flow control valve stroking rate to 1011% per second in the i
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apening and closing directions on a control signal failure. The analysis of the recirculation flow control failures on increasing and decreasing flow are presented in Sections 15.3 and 15.4 of the FSAR respectively.
1 The required surveillance interval is adequate to ensure that the flow ctntrol valves remain OPERABLE and not so frequent as to cause excessive wear Cn the systes components.
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J INSERT "A" BASES 3/4.4.1
...has been evaluated and.found to remain within design limits and safety margins provided certain limits and setpoints'are modified. The "GGNS Single Loop Operation Analysis" identified the fuel cladding integrity Safety Limit, MAPLHGR limit and APRM setpoint modifications necessary to maintain the same margin of safety for single loop operation as is available during two loop operation. Additionally, loop flow limitations are established to assure vessel internal vibration remains within limits. A flow control mode restriction is also incorporated to reduce valve wear due to automatic flow control attempts and to ensure valve swings into the cavitation region do not occur.
INSERT "B" During single loop operation, the condition may exist in which the coolant'in the bottom head of the vessel is not circulating. These differential temperature criteria are also to be met prior to power or flow increases from this condition, i
INSERT "C" Figure 3.4.1.1-1 describes the boundaries of the detect and suppress region as discussed in bases 3/4.3.10.
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J19 MISC 86072101 - 6 l
SUPPLEMENTAL INFORMATION TO THE RELOAD LICENSING SUBMITTAL VIA AECM-86/0214 As indicated in MP&L's submittal of July 14, 1986 (AECM-86/0214) to support licensing of the Cycle 2 core reload, a concern regarding the formulation of the COTRANSA Hot Channel model used to calculate delta-CPR values had been raised. The effects of this concern for Grand Gulf Unit 1 Cycle 2 were assessed using the XCOBRA-T code. The attached reports, Xh-NF-86-35, Revision 3, and XN-NF-86-36, Revision 3, include the information which was identified "to be supplied later" in Revision 2 of these reports.
The XCOBRA-T calculation confirmed the COTRANSA Hot Channel results.
All of the recalculated delta-CPRs support the proposed MCPR operating limits for Grand Gulf Unit 1 Cycle 1, which are being maintained for Cycle 2.
A detailed description of the XCOBRA-T calculations is given in Appendix B of XN-NF-86-36, Revision 3.
In view of the fact that the XCOBRA-T analyses confirmed the COTRANSA Hot Channel results, and the delta CPRs reported are the original delta CPRs, l
therc are no changes to the MCPR limits or the justification offered in the original submittal nor any technical specification changes.
Furthermore, there is no impact on the original "No Significant Hazards Considerations", as no changes from the previous submittal are being proposed.
g J11 MISC 86080901 - 1
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