ML13304A422
| ML13304A422 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 08/02/1989 |
| From: | Hickman D Office of Nuclear Reactor Regulation |
| To: | Baskin K, Cotton G San Diego Gas & Electric Co, Southern California Edison Co |
| References | |
| GL-88-0107, TAC-69774, TAC-69775 NUDOCS 8908140339 | |
| Download: ML13304A422 (5) | |
Text
9 4REG(,
UNITED STATES A,
NUCLEAR REGULATORY COMMISSION WASHINGTON, D. C. 20555 August 2, 1989 Docket Nus.
50-361 and 50-362 Mr. Kenneth P. Baskin Mr. Gary D. Cotton Vice President Senior Vice President Southern California Edison Company Engineering and Operations 2244 Walnut Grove Avenue San Diego Gas and Electric Company Post Office Box 800 101 Ash Street Rosemead, California 91770 Post Office Box 1831 San Diego, California 92112 Gentlemen:
SUBJECT:
SOUTHERN CALIFORNIA EDISON COMPANY RESPONSE TO GENERIC LETTER 88-17 WITH RESPECT TO EXPEDITIOUS ACTIONS FOR LOSS OF DECAY HEAT REMOVAL, SAN ONOFRE NUCLEAR GENERATING STATION, UNITS 2 AND 3 (TAC NOS. 69774 AND 69775)
Generic Letter (GL) 88-17 was issued on October 17, 1988, to address the potential for loss of decay heat removal (DHR) during nonpower operation. In the GL, we requested (1) a description of your efforts to implement the eight recommended expeditious actions of the GL and (2) a description of the enhance ments, specific plans and a schedule for implementation of the six recommended program enhancements.
The NRC staff has reviewed your response to Generic Letter 88-17 on expeditious actions contained in your letter of January 5, 1989. We find that your response is generally complete and appears to meet the intent of the generic letter with respect to expeditious actions. However, in a few areas, your response is sufficiently vague that we cannot fully understand the actions you have taken in response to GL 88-17. You may wish to consider the following observations in order to assure yourselves that your actions are adequate:
- 1. You have indicated that prior to entering a RCS reduced inventory condition, containment closure must be attainable within 2.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />, with cold leg openings of 1 square inch or less, and within 45 minutes, with cold leg openings greater than 1 square inch, unless a valid hot leg vent has been established. You have not discussed your method for quick closure of the equipment hatch. In some plants the quick closing of the equipment hatch is achieved by the installation of a reduced number of bolts. If you plan to use fewer than the full complement of bolts for sealing the equipment hatch, then you should first verify that you can make a proper seal of the periphery mating surfaces to meet the closure criteria.
Letter to Mssrs Baskin and Cotton August 2, 1989
- 2. For a hot leg vent, you have indicated that the pressurizer manway and steam generator hot leg manway will be used if these vent paths are not obstructed. You have not stated the particular vent opening that will be used. Pressurizer or steam generator manways are often removed to provide vent openings on the hot side of the RCS to relieve RCS pressurization. However, calculations need to be performed to verify the effectiveness of RCS openings, because even for relatively large hot side openings in the RCS, pressurization to several psi can still occur. For example, with removal of a pressurizer manway, large steam flows, in combination with flow restrictions in the surge line and lower pressurizer hardware, may still lead to pressurization.
- 3. With regard to provisions for two independent continuous indications.
of core exit temperature, you indicate that the selected indications will be the water covered unheated thermocouples of the heated junction thermocouple (HJTC) system or the core exit thermocouples which display on the plant qualified safety parameter display system (QSPDS) computer in the control room. You have not stated the location of the HJTC reading. Therefore we cannot determine if the HOTC system measures only peripheral temperatures near the region of the reactor wall and also if the readings are representative of the temperature values at the core exit height. The HJTC reading may not therefore represent as high a temperature as a typical average core exit thermocouple.
- 4. For RCS water level measurement you indicate that the primary method used is the reactor water level indication (RWLI) system. You state that this system provides wide range indication between the pressurizer and the bottom of the hot leg, and narrow range indication between the top and bottom of the hot leg. The indications are monitored and alarmed in the control room. This system also has a permanently installed hard-piped sight glass which indicates RCS water level between the reactor vessel flange and 7 inches below the centerline of the 42-inch hot leg. You state that both of these indications connect to the same sensing taps. Since common taps are used, extra care is needed to avoid common errors in level measure ment. The accuracy of the level readings is not provided. When two or more level instruments are in place, care should be taken to resolve any discrepancy between the measurement systems. Also, the pressure of the preference leg should approximate the pressure of the void in the hot leg or be compensated to obtain the correct level value.
You have also presented three additional methods for level indication while draining is in progress. One makes use of the HJTCs No. 3, 4, 5 and 6 using the QSPDS computer. You state that this method is not useful after uncovery of HJTC No. 6 (at centerline of the hot leg) since LPSI pump vortexing will occur before reaching HJTC No. 7.
Your second method involves calculating cumulative gallons drained
Letter to Mssrs. Baskin and Cotton August 2, 1989 and comparing this data to known RCS volumes. You have indicated an additional indirect secondary method of level indication which is the LPSI pump amperage. You state that the control room frequently monitors the LPSI pump amperage oscillations as it is a precursor to major vortexing. These three additional methods for level determination are not as desirable as the primary method for obtaining a direct, continuous level reading but are helpful for supplying supplemental information.
- 5. For the expeditious action regarding provision of at least two available or operable means of adding inventory to the RCS that are in addition to pumps that are a part of the normal DHR system, you have provided information on two means. One of these means is a high pressure safety injection (HPSI) pump. The second means is either a containment spray pump or a charging pump. You have not described the injection path. As alluded to in Enclosure 2, Section 2.2.2 of GL 88-17, if openings totaling greater than 1 square inch exist in the cold legs, reactor coolant pumps and crossover piping of the RCS, the core can uncover quickly when pressurized under loss of RHR conditions. If this situation should arise, it is generally more effective to inject makeup water into the hot leg rather than the cold leg.
There is no need to respond to the above observations.
As you are aware, the expeditious actions you have briefly described are an interim measure to achieve an immediate reduction in risk associated with reduced inventory operation, and these will be supplemented and in some cases replaced by programmed enhancements. We intend to audit both your response to the expeditious actions and your programmed enhancement program. The areas where we do not fully understand your responses as indicated above may be covered in the audit of expeditious actions.
This closes out the staff review of your responses to the expeditious actions listed in the GL. The area of programmed enhancements will be addressed in a separate letter.
Sincerely, Donald E. Hickman, Project Manager Project Directorate V Division of Reactor Projects - III, IV, V and Special Projects Office of Nuclear Reactor Regulation cc:
See next page
Letter to Mssrs. Baskin and Cotton August 2, 1989 and comparing this data to known RCS volumes. You have indicated an additional indirect secondary method.of level indication which is the LPSI pump amperage. You state that the control room frequently monitors the LPSI pump amperage oscillations as it is a precursor to major vortexing. These three additional methods for level determination are not as desirable as the primary method for obtaining a direct, continuous level reading but are helpful for supplying supplemental information.
- 5. For the expeditious action regarding provision of at leasttwo available or operable means of adding inventory to the RCS that are in addition to pumps that are a part of the normal DHR system, you have provided information on two means. One of these means is a high pressure safety injection (HPSI) pump. The second means is either a containment spray pump or a charging pump. You have not described the injection path. As alluded to in Enclosure 2, Section 2.2.2 of GL 88-17, if openings totaling greater than 1 square inch exist in the cold legs, reactor coolant pumps and crossover piping of the RCS, the core can uncover quickly when pressurized under loss of RHR conditions. If this situation should arise, it is generally more effective to inject makeup water into the hot leg rather than the cold leg.
There is no need to respond to the above observations.
As you are aware, the expeditious actions you have briefly described are an interim measure to achieve an immediate reduction in risk associated with reduced inventory operation, and these will be supplemented and in some cases replaced by programmed enhancements. We intend to audit both your response to the expeditious actions and your programmed enhancement program. The areas where we do not fully understand your responses as indicated above may be.
covered in the audit of expeditious actions.
This closes out the staff review of your responses to the expeditious actions listed in the GL. The area of programmed enhancements will be addressed in a separate letter.
Sincerely, original signed by Donald E. Hickman, Project Manager Project Directorate V Division of Reactor Projects.- III, IV, V and Special Projects Office of Nuclear Reactor Regulation cc: See next page DISTRIBUTION Docket File JLee BGrimes D
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NRC & LPDRs DHickman ACRS (10)
DH~ckma :dr ton PD5 Reading OGC
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MVirgilio EJordan
Mr. Kenneth P. Baskin San Onofre Nuclear Generating Southern California Edison Company Station, Units 2 and 3 cc:
Charles R. Kocher, Esq.
Mr. Mark Medford James A. Beoletto, Esq.
Southern California Edison Company Southern California Edison Company 2244 Walnut Grove Avenue 2244 Walnut Grove Avenue P. 0. Box 800 P. 0. Box 800 Rosemead, California 91770 Rosemead, California 91770 Mr. Robert G. Lacy Orrick, Herrington & Sutcliffe Manager, Nuclear Department ATTN: David R. Pigott, Esq.
San Diego Gas & Electric Company 600 Montgomery Street P. 0. Box 1831 San Francisco, California 94111 San Diego, California 92112 Alan R. Watts, Esq.
Dr. Gerard C. Wong, Chief Rourke & Woodruff Radiological Materials Control 701 S. Parker St. No. 7000 Section Orange, California 92668-4702 State Department of Health Services 714 P Street, Building #8 Mr. Sherwin Harris Sacramento, California 95814 Resource Project Manager Public Utilities Department Resident Inspector, San Onofre NPS City of Riverside co U.S. Nuclear Regulatory Commission 3900 Main Street Post Office Box 4329 Riverside. California 92522 San Clemente, California 92672 Mayor, City of San Clemente Mr. Charles B. Brinkman San Clemente, California 92672 Combustion Engineering, Inc.
12300 Twinbrook Parkway, Suite 330 Regional Administrator, Region V Rockville, Maryland 20852 U.S. Nuclear Regulatory Commission 1450 Maria Lane/Suite 210 Mr. Roy Zimmerman Walnut Creek, California 94596 U.S. Nuclear Regulatory Commission Region V Chairman, Board of Supervisors 1450 Maria Lane, Suite 210 San Diego County Walnut Creek, California 94596 1600 Pacific Highway, Room 335 San Diego, California 92101 Mr. Don Womeldorf Chief Environmental Mangement Branch Mr. F. B. Marsh, Project Manager California Department of Health Bechtel Power Corporation 714 P Street, Room 616 P.O. Box 60860 Sacramento, California 95814 Terminal Annex Los Angeles, California 90060 (15)