ML18051B409
| ML18051B409 | |
| Person / Time | |
|---|---|
| Site: | Palisades  |
| Issue date: | 06/04/1985 |
| From: | Johnson B CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8506070029 | |
| Download: ML18051B409 (6) | |
Text
consumers Power company General Offices: 1945 West Parnell Road, Jackson, Ml 49201 *:l517J 71;18-0550 June 4, 1985
- Director, Nuclear Reactor Regulation US Nuclear Regulatory Commission Washington, DC 20555 DOCKET 50-255 - LICENSE DPR PALIS.ApES.PLANT -: FIRE* PROTECTION - LOCAL TENDING OF EMERGENCY GENERATORS (ADDITIONAL INFORMATION)
Consumers Power Company exemption request - Local Tending of Emergency
- Generators - dated August 10, 1984 provided information as to the method which the Palisades plant proposed to isolate the remote control of essential hot shutdown equipment.
Although the method described in that exemption request (using slide-links that are opened and closed by an electrician called in from offsite) was disallowed by the NRC in their letter dated February 13, 1985 and is no longer planned for use, the amount of time that the PCS will stay 25°F sub-cqoled is still needed.
This time interval must be quantified so as to confirm the time that operators have to manually open or close certain valves which may be located in the fire area.
The NRC letter dated February 13, 1985 requests additional information.
On March 13, 1985, Consumers Power *Company.requested that.the due date for this additional information be changed from April 19, 1985 to**June l; 1985~ *The requested additional information is provided here.
Additional Information Items and Responses Item
- 1.
The Consumers Power Company must provide a submittal that describes the calculations used to determine the time available without a-c power before the subcooling reduces to 25°F. to Attachment lA of the August 10,, 1984 submittal ref,erences CEN-125.
We have not been able to find that this report has been docketed or reviewed.
Therefore, it is not a valid reference.
The calculations that you provide should not rely on CEN-125.
8506070029 850604
. ~DR ADOCK o~g~~-
OC0585-0023B-NL02
Director, Nuclear Reactor Regulation Palisades Plant Fire Protection - Emerg. Generators June 4, 1985
Response
2 The case was rerun using RETRAN-02 (Ref 1) to include ambient heat losses from the pressurizer and thus eliminate any reliance on CEN-125.
Item
- 2.
The Consumers Power Company performed the calculation using the RETRAN computer code.
However, a topical report for its use was never submitted for NRC approval (Ref. Generic Letter 83-11).
Therefore, more details regarding the calculation are neces~ary (e.g.,
assumptions, initial conditions, methodology, any check calculations compared to actual plant transients).
Response
A brief description of the model, the initial conditions used, and any assumptions made is presented.
The model as shown in Fig 2 consists of 4 volumes and 4 junctions and 1 non-conducting heat exchanger.
Volume 300 represents the pressurizer.
Pressure was initially set at 1760 psia with a volume averaged enthalpy of 718.1 BTU/LBm.
The Pressure is 250 psi. lower than the normal pressurizer pressure of 2010 psia, is to account for the expected out-surge from the pressurizer following the reactor trip and is a very conservative assumption.
Volume 301 represents the surge line, and 302 the primary system.
The initial pressures for these volumes were set at 1765 and 1767 psia respectively to account for the elevation difference with the pressurizer.
The en~halpies were then interpolated from the steam tables assuming the primary system is being controlled at 560°F by the operator.
Volume 1 represents containment and is used as a sink for the leakage from the primary system. It is a time dependent volume with the pressure and temperature held constant at 14.7 psia and 100°F respectively.
By holding these containment parameters constant.it is easier to maintain the desired maximum leak rate throughout the problem.
Per Palisades Technical Specifications (Section 3.1.5), the maximum leak rate from the primary coolant system is 1 GPM unidentified, and 10 GPM total.
In addition the 4 GPM flow through the PCP seals to the Volume Control tank is the same as a leak from the PCS since there is no charging.
Thus, the maximum allowed loss from the PCS will be 14 GPM.
The ambient heat losses through the pressurizer were assumed to be.152 MW.
This is the PCS heat losses measured during hot functional testing.
This heat was removed by the use of the non conducting heat exchanger option of the RETRAN code.
This option simply allows the removal of heat via a table of energy to be removed vs. time.
The worst case was determined to be a 1 GPM steam.leak accompanied by a 14 GPM water leak.
The results shown in Fi&* 1 show sub cooling is maintained for 2.25 hrs.
OC0585-0023B-NL02
Director, Nuclear Reactor Regulation Palisades Plant Fire Protection - Emerg. Generators June 4, 1985 Item 3a. "What are the flow requirements of the AFW?"
Response
3 As stated in Consumers Power Company letter dated August 11, 1982, "Auxiliary Feedwater Modification (Additional Information)," the AFW flow requirements are 325 GPM to one steam generator on line or 300 GPM to both steam generators (150 GPM each).
Item 3b. "Are these automatic or manual?"
Response
Initiation and subsequent flow control is automatic in all fire scenarios except those requiring the use of the Alternate Shutdown Panel (ASP).
Fires in the Control Room, Cable Spreading Room, 590' corridor or Engineered Safeguards Panel Room may require use of the ASP.
At the ASP, flow is controlled manually by an operator using hand controllers which modulate the AFW supply valve through an electro-to pneumatic converter.
The operator determines the required flow by observing Steam Generator Level Indicators.
Item 3c. Discuss the effects of insufficient flow and excess flow on subcooling.
Response
Insufficient AFW flow will decrease the time the PCS would remain sub-cooled.
Excess flow would increase the time the PCS remain-s sub-cooled.
Since AFW flow can be manually controlled from the ASP, as well as by 2 back up methods while observing steam generator level indication, we do not consider that AFW flow will deviate from desired rates.
The two backup methods are (1) manual operation of the AFW in line motor operated valves and (2) starting and stopping the turbine driven AFW pump.
Item 3d. Address the potential for upperhead voiding with too rapid a cooldown and its effect on natural circulation.
Response
roo rapid a cooldown is not postulated unless the atmospheric dump valves (ADV) are given an open signal by a hot.short or open in their control OC0585-0023B-NL02
Director, Nuclear Reactor Regulation Palisades Plant Fire Protection June 4, 1985 Emerg. Generators 4
circuit. If the ADV's open at an undesirable time, the in-line upstream manual valve can be closed.
Pressure would be maintained by the charging system.
With the Palisades Primary Coolant System elevations, head voiding, while not desirable, would not have a large effect on natural circulation until the reactor coolant level falls below the hot leg.
Since the charging system is maintained in all fire scenarios, the coolant level will not fall below the hot leg.
References
- 1. NRC letter dated September 2, 1984 from C.O. Thomas to TWSchmatz, Middle South Seririces, Inc.
Brian D Johnson Staff Licensing Engineer CC Administrator, Region III, USNRC NRC Resident Inspector - Palisades OC0585-0023B-NL02
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