ML13330A067
| ML13330A067 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 06/23/1980 |
| From: | Baskin K Southern California Edison Co |
| To: | Crutchfield D Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML13330A068 | List: |
| References | |
| TASK-06-04, TASK-6-4, TASK-RR NUDOCS 8007010465 | |
| Download: ML13330A067 (5) | |
Text
Southern California Edison Company,.
P.
- 0.
BOX 800 2244 WALNUT GROVE AVENUE ROSEMEAD.
CALIFORNIA 91770 K. P. BASKIN TELEPHONE MANAGER, NUCLEAR ENGINEERING (213) 572-1401 AND LICENSING June 23,.1980' Director of Nuclear Reactor Regulation Attention:
D. M. Crutchfield, Chief Operating Projects Branch No. 5 Division of Project Management U.S. Nuclear Regulatory Commission Washington, D.C. 20555 Gentlemen:
Subject:
Docket No. 50-206 Systematic Evaluation Program San Onofre Nuclear Generating Station Unit 1 By letters dated April 17, and June 12, 1980, the NRC requested additional information regarding SEP Topic VI-4, Containment Isolation System. Provided as an enclosure to this letter are the responses to that request.
If you have any additional questions regarding this matter, please let me know.
Very truly yours, Enclosure 800701O45
Additional Information for Purging and Venting System San Onofre Unit 1 ITEM 1 Provide the process and instrumentation diagram (P&ID) and schematic diagrams for the purge and vent system.
RESPONSE
The following drawings are provided as an enclosure:
568782 Rev. 18 -
P&ID Diagram Air Conditioning System 5149857 -
Rev.
2 -
Elementary Diagram Purge, Press Equalizer & Isolation Valves, Instrument Air System and Dampers ITEM 2 SCEC 1/9/79 letter indicates that when a manual override of the safety injection actuation signal is affected, this also overrides the containment spray actuation signal and the containment purge isolation valves.
The NRC guidelines required that, for any override, an annunciator be provided for each system impacted when the override is active.
Describe how the San Onofre 1 design meets this guideline.
RESPONSE
The automatic containment isolation valves at San Onofre Unit 1 close on either a containment high pressure (above 2 psig) signal or a safety injection actuation signal.
The automatic isolation valves in the purge and vent system will also close on receipt of a high radiation signal. Manual override of the safety injection actuation signal will block the signal to the isolation valves, such that, the valves will close only on a containment high pressure signal with the exception of the purge and vent valves which will also close on a containment.high radiation signal.
Blocking the safety injection actua tion signal also affects the containment spray actuation system logic such that automatic actuation of containment spray will not occur.
An annunciator is provided in the control room that indicates the safety injection actuation signal is blocked.
There is no individual annunciator which indicates the containment isolation system logic has been affected by the blocking of the safety injection actuation signal since the other isolation signals are not affected. There is no individual annunciator which indicates the containment spray actuation system logic has been affected since operation of this system is directly associated with operation of the safety injection system.
-2 ITEM 3 SCEC 1/9/79 letter describes that manual override of the safety injection actuation signal is accomplished by use of a manual "double-action block switch".
The NRC guideline requires that override controls have sufficient physical features (i.e., keylock switches or covered switches) to facilitate adequate administrative control.
Describe how the "double-action block switch" satisfies the NRC guideline.
RESPONSE
Associated with each of the two safety injection trains is a safety injection block switch.
The override for each train is accomplished by operating the particular spring return double-action block switch for each train.
The double-action involves pulling out the switch control lever and rotating it clockwise for the block position.
Releasing the control lever allows it to return to its normal position while initiating the block of the associated safety injection train.
It requires two actions (double-action) for the operator to block a single safety injection train.
Operation of two block switches is required to block the entire safety injection system.
This double-action feature is considered to provide sufficient administrative control of the safety injection block switch.
ITEM 4 The NRC guideline requires signals which initiate containment isolation be derived from safety grade equipment.
Discuss the qualifications of the equip ment providing the (a) high containment pressure, (b) high containment radiation, and (c) safety injection actuation signals.
RESPONSE
The environmental qualification of electrical equipment required to mitigate post-accident conditions is discussed in SCE's letter to the NRC dated June 18, 1980.
(a) The pressure transmitters which initiate the containment high pressure signal are located outside containment.
They are Foxboro E11GM's which have been environmentally qualified to 3000F, 75 psia, 100% relative humidity, chemical spray and a radiation dose of 2.2 X 108 rads.
These values exceed the post-accident environmental conditions for the area in which the transmitters are located.
(b) The radiation monitor which initiates the high containment radiation signal was not addressed in the June 18, 1980 submittal.
The post-accident environmental conditions for the area in which the monitor is located was discussed. The monitor is located outside containment in the ventilation equipment building.
The June 18, 1980 submittal indi cates that this area will remain at ambient conditions following an accident and the post-aaccident radiation doses will be insignificant.
Therefore, the monitor will experience conditions similar to those during normal operations and is considered to be qualified based on experience.
-3 (c) The pressure transmitters which initiate the safety injection.actuation signal are the pressurizer pressure transmitters located inside contain ment in the pressurizer instrument cabinet and the containment pressure transmitters discussed in (a) above.
The pressurizer pressure transmit ters are also Foxboro E11GM's qualified to 300 0F, 75 psia, 100 relative humidity, chemical spray and a radiation dose of 2.2 X 100 rads.
These values exceed the post-accident environmental conditions following a LOCA inside containment as indicated in the June 18, 1980 submittal.
ITEM 5 The NRC guideline requires that overriding or resetting of the isolation actuation signal does not cause automatic reopening of any isolation or purge valve. Discuss how the San Onofre Unit 1 design meets this guideline.
RESPONSE
San Onofre Unit 1's compliance with this guideline is discussed in Item 2.1.4 of the Additional Information/Actions to Implement the Category A Lessons Learned Requirementssubmitted to the NRC by letter dated March 25, 1980.