ML13317A328
| ML13317A328 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 09/17/1982 |
| From: | Krieger R Southern California Edison Co |
| To: | Crutchfield D Office of Nuclear Reactor Regulation |
| References | |
| TASK-03-03.C, TASK-3-3.C, TASK-RR NUDOCS 8209210109 | |
| Download: ML13317A328 (4) | |
Text
Southern California Edison Company P. 0. BOX 800 2244 WALNUT GROVE AVENUE ROSEMEAD. CALIFORNIA 91770 September 17, 1982 Director, Office of Nuclear Reactor Regulation Attention:
D. M. Crutchfield, Chief Operating Reactors Branch No.
5 Division of Licensing U. S. Nuclear Regulatory Commission Washington, D.C.
20555 Gentlemen:
Subject:
Docket No. 50-206 SEP Topic III-4.C San Onofre Nuclear Generating Station Unit 1 By letter dated July 16, 1982 you forwarded a request for additional information in connection with your review of SEP Topic III-4.C, Internally Generated Missiles.
The requested information is provided as an enclosure to this letter.
If you have any questions in any of this information, please let us know.
Very truly yours, R. W. KriegerO Supervising Engineer San Onofre Unit 1 Licensing Enclosure P
VP'bRU
REQUEST FOR ADDITIONAL INFORMATION SEP TOPIC III-4.C SAN ONOFRE UNIT 1 Item Standard Review Plan 3.2.2 identifies a list of fluid systems important to safety. The following systems from this list were not explicitly addressed in your evaluation.
For each system, either discuss what other systems provide that safety function and where such systems are evaluated in the topic assessment or provide an evaluation of the system with respect to Topic III-4.C.
- a.
Steam Generator Blowdown System
- b. Containment Cooling System
- c. Combustible Gas Control System
- d. Spent Fuel Pool Cooling and Cleanup System
- e. Emergency Diesel Engine Cooling Water System
- f. Emergency Diesel Engine Starting System
- g. Emergency Diesel Engine Lubricating System
- h. Emergency Diesel Engine Combustion Air Intake and Exhaust System
Response
- a.
Steam Generator Blowdown System The steam generator blowdown system is not considered a system which is important to safety. The consequences of steamline breaks are discussed in Topic XV-2, Spectrum of.Steam System Piping Failure Inside and Outside Containment.
- b. Containment Cooling System The containment cooling system consists of 17 air handling units which circulate and cool air in various parts of the containment.
However, this equipment is not safety related and therefore failure of this equipment due to internal missiles will not affect safety.
Following an accident, containment cooling is accomplished by the containment spray system which was discussed in paragraph V.1.g.1 of SCE's April 29, 1982 assessment of Topic III-4.C.
- c. Combustible Gas Control System Two hydrogen recombiners are provided on opposite sides of the containment. No missile could affect both units. These are passive items and therefore incapable of generating missiles.
- d. Spent Fuel Pool Cooling and Cleanup System This system was discussed in paragraph V.2.d of SCE's April 29, 1982 assessment.
-2
- e.
Emergency Diesel Engine Cooling Water System The diesel generators and all of their auxiliary systems were addressed in paragraph V.1.k of SCE's April 29, 1982 assessment.
- f. Emergency Diesel Engine Starting System See item e.
- g.
Emergency Diesel Engine Lubricating System See item e.
- h.
Emergency Diesel Engine Combustion Air Intake and Exhaust System See item e.
- 2.
Item Provide an evaluati:on of potential missiles which could be ejected from the reactor coolant pump motor.
Response
Missiles from the reactor coolant pump motor were addressed in paragraph V.1.a of SCE's April 29, 1982 assessment. It is unlikely that missiles would be ejected from the motor because of its thick case.
- However, generation of missiles from overspeed of motor, fly wheel and the impeller is a generic issue which is being reviewed under Task Action Plan B-68, "Pump Overspeed During a LOCA."
- 3.
Item Provide an evaluation of the effects of missile generation along the CVCS letdown line inside containment.
Response
No missiles have been identified which could adversely affect the CVCS letdown line between the reactor coolant loop and the first isolation valve (FCV 1112).
The system downstream of this valve can be isolated so the effects of missile damage can be mitigated. If letdown is unavailable, the RCS can be depressurized using pressurizer spray and the PORV's if necessary.
- 4.
Item Discuss applicable valve design aspects which preclude missile generation of valve stems, bonnet ejection and unrestrained valve-operators.
-3
Response
(Later)
- 5.
Item Provide an evaluation of the missile protection afforded to electrical and instrumentation cables required for systems important to safety.
Identify vulnerable cables and associated systems which could suffer degradation upon cable severence.
Response
As a result of. the requirements of Appendix R of 10 CFR 50, modifications and/or additions are going to be made to the electrical and control cables to enable safe shutdown to be achieved in case of fire. Among these modifications and/or additions will be the realignment of several items from one electrical train to another to provide separation of electrical trains in case of fire. This separation may consist of either physical separations or fire barriers. While not specifically designed to provide missile protection, these separations or barriers will also provide missile protection since one missile would be unlikely to damage both electrical trains.
(See K. P. Baskin's letter to D. M. Crutchfield dated June 30, 1982.)
JLR:5544