ML20033A722
| ML20033A722 | |
| Person / Time | |
|---|---|
| Site: | Perry  |
| Issue date: | 11/20/1981 |
| From: | Davidson D CLEVELAND ELECTRIC ILLUMINATING CO. |
| To: | Tedesco R Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8111270160 | |
| Download: ML20033A722 (5) | |
Text
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' THE CLEVELAND ELECTRIC ILLUMIN ATING COMPANY P.o Box 5000 m CLEVELAND, oHlo 44101 e TELEPHONE (216) 622-9800 m ILLUMINATING OLDG e 55 PUBLIC SoUARE Sarving The Best Location in the Nation D lwyn R. Davidson SYSTEM ENGtNEERING AND CONSTRUCTION 1 W VtCE PRESIDENT
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g November 20, 1981 g{t Mr. Robert L. Tedesco NOV2 519815 9 Assistant Director for Licensing u.s.umrue m Division of Licensing
"'83 W N
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U. S. Nuclear Regulatory Commission
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Washington, D. C.
20555 I Qj y,
Perry Nuclear Power Plant
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Docket Nos. 50-% 0; 50- W 1 Response to Request for Additional Information -
Reactor Systems
Dear Mr. Tedesco:
This letter and its attachment is submitted to provide draft responses to the concerns identified in your letter dated October 30, 1981 in regard to Reactor Systems.
It is our intention to incorporate these responses in a subsequent amendment to our Final Safety Analysis Report.
Very Truly Yours, Dal R. Davidson Vice President System Engineering and Construction DRD: mlb 3 00/
Attachment 3
cc:
G. Charnoff, Esq.
f M. Dean Houston j/[
NRC Resident Inspector i
Ohhf[ff0 C
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WO.21 "Section 5.4.7.1.5 of the Perry FSAR considered alternate shutdown cooling methods in the event the residual heat removal (RHR) system in the suction line may not be used.because of valve failure. Valves in the automatic depressurization ~ system (ADS) are used to transfer fluid.
(steam, water or a combination of these) from the reactor vessel-to the suppression pool. The RHR system removes the added heat by. cooling water removed from the suppression pool and injecting it to the reactor vessel.
We require that you cite test results or submit analysis to demonstrate that the ADS valves can discharge the fluid flow under the most limiting conditions when the fluid is all water. Show that this alternate method is a viable means of shutdown cooling by comparing the system hydraulic losses with the available pump head. Hydraulic losses should be provided for each system component and wherever possible, should be derived from experimental results.".How much time is required to achieve cold shutdown by this alternating method assuming one RHR train'only is available for pool cooling?
Response
The ADS valves for the Perry plant, which are of the Dikkers type, were.
operationally tested as described in NEDE-24988-P for the most limiting conditions for the alternate shutdown cooling mode, as required above.
The discharge fluid was single-phase liquid water..The test procedure, facility description and results show that the Dikkers valve used on Perry operat'ed satisfactorily. In addition, the loads from the liquid discharge on the valve and discharge piping were considerably lower than the design basis loads. Both valve and discharge piping integrity
~
were verified following the liquid discharge testing.
The test results also showed that there is a considerable excess of. total valve capacity to pass the required flow rate for alternate shutdown cooling, 1. e. only 1 or 2 valves is required to pass the needed flow..
Consequently, the hydraulic losses will result in a system pressure which is' low enough to allow the low pressure pumps to inject sufficient suppression pool water into the vessel. As noted in Figure 6.3-73 of the Perry FSAR, the additional head required to flood the steamlines will have a negligible effect on the pump flow rate.
i The time required to achieve cold shutdown using the alternate shutdown cooling mode can be less than the time to achieve cold shutdown using the normal shutdown cooling mode of the RHR system. However the recommended rate of cool down is 1000F per hour.
440.22 Operation of the RHR system in the steam condensing mode involves (5.4.7) partial draining of one or both RHR heat exchangers and introduction of reactor steam into initially cold line and heat exchangers.
Describe the methods (e.g., valve operation, air introduction, etc.)
and provisions to be used to prevent occurrence of water hammer during the initiation of operation in this mode, and the change to the pool cooling mode. When the RHR is used in the steam condensing mode with one or both heat exchangers, can the jockey pump system fill the lines to the injection valve in the core spray and RHR lines? If not, what procedures would be ut. I to prevent water hammer following startup of the core spray or RHR pump.
Pressure relief valves and lines designed to prevent over-pressurization of the RHR system are routed outside containment before being returned to the suppression pool. Discuss design provisions made to mitigate possible water hammer in these lines.
Response
The methods used to prevent the occurrence of water hammer during steam condensing initiation are: 1) lowering the heat exchanger water level before steam is admitted to provide an expansion volume for the steam,
- 2) opening the heat exchanger non-condensable vents before steam is admitted to provide a discharge path, 3) initially admitting steam at a low pressure and slowly increasing steam pressure to 200 psig to avoid high pressure surges, and 4) opening rdi valves slowly to avoid sudden flow surges.
The methods used to prevent the occurrence of water-hammer following steam condensing termination and change to the pool cooling mode are:
- 1) closing the heat exchanger condensate discharge and letting the continuing condensation raise the water level until the rate of increase becomes very slow, 2) opening the valves connecting the heat exchanger to the main pump loop, and 3) opening the high point vent and filling the heat exchanger shell and connecting piping using the jockey pumps.
When the RHR system is used for steam condensing, the LICI injection loop is isolated from the heat exchanger steam flow by closing FOO3 and F047. Use of steam condensing mode has no effect on the jockey pump ability to fill the lines to the injection valves in the core spray or RHR lines and, therefore, the jockey pumps can fill these lines.
The RHR pressure relief lines are routed to the suppression pool area via the RCIC turbine exhaust vacuum relief line. These lines continually slope downward toward the suppression pool to prevent water accumulation in the line thus minimizing water hammer.
E 440.23 Discuss the procedures for minimizing the potential for exceeding (5.4.7) the allowable cooldown rate (greater than 100 degrees Fahrenheit /
hour) of the RHR and the Reactor Coolant System when placing the plant in a shutdown cooling mode following planned normal conditions or an emergency.
Response
When either the normal shutdown cooling mode or the alternate shutdown cooling mode (SRV return to pool) is used, the operator controls the cooldown rate by throttling the reactor coolant flow through the heat exchanger using F003 The operator determines the cooldown rate by mon-itoring reactor coolant temperature change with time and by plotting this temperature. This temperature vs. time plot is compared with a 100 F per hour cooldown rate line. The slope of the plotted line is 0
0 always maintained less than or equal to the 100 F rate line. The operator will plot this temperature at intervals not to exceed 15 minutes.
m
440.24 Discuss the RHR pump reliability for long-term operation. Long-term (5.4.7) reliability should be demonstrated by either operational experience or testing. If previous operational experience should be cited as the
' oasis for qualifying the pumps, state any pump design differences and conditions of previous pump operations.
Response
'Ihe response to this question will be provided as part of a LRG-II submittal.
(9-RSB)