ML17298A312
| ML17298A312 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde  |
| Issue date: | 04/20/1983 |
| From: | Novak T Office of Nuclear Reactor Regulation |
| To: | Van Brunt E ARIZONA PUBLIC SERVICE CO. (FORMERLY ARIZONA NUCLEAR |
| References | |
| NUDOCS 8305030013 | |
| Download: ML17298A312 (8) | |
Text
APR 2 01983 DDcket Nos.:
50-528, 50-529 and 50-530 t1r. E. E.
Van Brunt, Jr.
Vice President - Nucle'ar Projects Arizona Public Service Company Post Office Box 21666 Phoenix, Arizona 85036
Dear Nr. Van Brunt:
p DISTRIBUTION Document Control 50-528/92K/530 NRC PDR L PDR NSIC PRC System LB//3 Reading JLee EALicitra
- Attorney, OELD
THNovak DGEisenhut
Subject:
CE Owners Group Study on Depressurization and Decay Heat Removal Capability of CE Plants Without PORVs The CE Owners Group (GEOG) and the NRC staff met in Bethesda, Maryland, on Wednesday, January 12, 1983 and discussed the status of the efforts to address the ACRS concern and staff questions on the CE plants without pressur izer PORVs.
Hr. T. quan of your staff was in: attendance: at this meeting.
The meeting was structured to exchange information and suggestions between the CEOG and NRC staff.
A number of calculations were presented by the CEOG and the staff.
The staff agreed to send their comments to the CEOG and all applicants and licensees involved, including San Onofre Units 2 and 3, Waterford 3, CESSAR 80, WNP 3, and Palo Verde Units 1, 2 and 3.
Enclosure 1 contains the staff comments in this regard.
During the April 4, 1983, Commission meeting on the above subject, the schedules currently proposed by the GEOG members were discussed.
The Commission expressed concern that the schedules for the submittal of PRA and other plant specific information for Waterford (August 15, 1983) and'Palo Verde (September 15, 1983) are excessive.
As a result of the Commission's
- concern, we now intend to make our decision regarding the need for PORVs in the plants based on all information received by June 30, 1983.
Thus, you should ensure that the necessary information has been submitted to the NRC staff by this date if you wish it to be considered in.t our decision-making process.
Sincerely, Original signed 57o Thomas M. HovW 83050300i3 830420 POR AaaCX 0S000Saa PDR I
i
Enclosure:
As stated Thomas H. Novak, Assistant Director for Licensing Division of Licensing OFFICE[
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NRG FORM 318 u0-80) NRCM 0240 OFFlClAL RECORD COPY USGPO: 1981~960
Palo Verde Mr, E.
E.
Van Brunt, Jr.
Vice President
-- Nuclear Projects Arizona Public Service Company P. 0.
Box 21666 Phoenix, Arizona 85036 CC:
Arthur C. Gehr, Esq.
Snell 5 Wilmer 3100 Valley Center Phoenix, Arizona 85073 Charles S. Pierson Assistant Attorney General 200 State Capitol 1700 West Washington Phoenix, Arizona 85007 Charles R. Kocher, Esq., Assistant Counsel James A. Boeletto, Esq.
Southern California Edison Company P. 0.
Box 800
- Rosemead, California 91770 Ms. Margaret Walker Deputy Director of Energy Programs Economic Planning and Development Office 1700 West Washington Phoenix, Arizona 85007 Regional Adminstrator-Region V
U. S. Nuclear Regulatory Commission 1450 Maria Lane Suite 210 Walnut Creek, California 94596 Kenneth Berlin, Esq.
Winston 5 Strawn Suite 500 2550 M Street, N.
W.
Washington, D.
C.
20037 Lynne Bernabei Government Accountability Project of the Institute for Policy Studies 1901 Que Street, N.
W.
Washington, D.
C.
20009 Mr. Rand L. Greenfield Assistant Attorney General Bataan Memorial Building Santa Fe, New Mexico 87503 Resident Inspector Palo Verde/NPS U. S. Nuclear Regulatory Commission P. 0.
Box 21324 Phoenix, Arizona 85001 Ms. Patricia Lee Hourihan 6413 S.
26th Street Phoenix-. Arizona 85040
ENCLOSURE 1
STAFF COMMENTS ON CE OWNERS GROUP STUDY ON DEPRESSURIZATION AND DECAY HEAT REMOVAL CAPABILITY OF CE PLANTS WITHOUT PORVs The GEOG is calculating the ability of a hypotentical pressurizer PORV to mitigate a total LOFW accident by accomplishing feed and bleed.
The PORV size, for this study, was arrived at based on a loss of all feedwater scenario where offsite power is retained, reactor trip occurs on low SG level, and the RCPs operate for 10 minutes before being man-ually tripped.
This scenario leads to a PORV larger than the Dresser PORVs that are used in other PWR Plants.
A PORV of this size may cause difficulties in controlling RCS pr essure.
The GEOG should not just consider this scenario when arriving at a
PORV size and operator action time.
The CE Owners Group should consider a spectrum of initiating LOFW events.
The overall conclusion regarding the PORV should not be based on more, extremely limiting, scenario; but must consider other, perhaps more likely scenarios.
If a large PORV is warranted to achieve feed and bleed, multiple smaller PORVs should be examined to replace the larger PORV for acceptable RCS pressure control.
The LOFW scenarios should evaluate the capability of the auxiliary pressurizer spray system for accident mitigation.
A comparison should be made of the capabilities of the auxiliary pressurizer spray system to hypothetical PORV in terms of preventing or delaying core uncovery.
The SGTR calculations should be expanded to assess the systems performance, operator actions and overall offsite consequences, should the PORV be used early in the event to depressurize'he RCS.
The calculations presented at the meetings only showed an assessment of early use of the auxiliary pressurizer spray systems.
The SGTR calculations should be expanded to assess the systems performance, operator actions and overall offsite consequences, should there be multiple ruptures in both steam generators, and assuming the use of a PORV depressurizing the RCS to stop the leaks and to establish feed and bleed early in the event to stop secondary releases.
The calculations presented at the l./12/83 meeting only showed the useof the auxiliary pressurizer spray after a multiple SGTR accident.
There are uncertainties in the codes in terms of determining flow distribution in RCS.
The recovery times are dependent on the hydraulic characteristic of the system.
The effects on PORV size and operator action time should be addressed in the study.
The scenarios considered in the GEOG study should reflect the current emergency response guidelines rather than taking credit for depressurization concurrent with the RCS cooldown.
~l
7.
In the SGTR and LOFW studies the GEOG should investigate the effects of an early loss of RCP flow as a result of the loss of offsite power concurrent with either the initiating event or with the reactor and turbine trip.
8.
GEOG study should consider a
SGTR concurrent with a MSLB and analyze it with either the PORV or APS available for accident mitigation.
9.
The SGTR calculations should consider a limiting single active failure concurrent with the accident to assess potential radiological consequences.
For CE plants without block valves upstream of the SG atmospheric steam dump valves (ADVs), the consequences of a stuck open ADV should be examined since the current procedures instruct the operator to manually open these valves early in the event.
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