ML13330A381
| ML13330A381 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 08/18/1981 |
| From: | Moody W Southern California Edison Co |
| To: | Crutchfield D Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML13330A382 | List: |
| References | |
| TASK-06-07.B, TASK-6-7.B, TASK-RR NUDOCS 8108200403 | |
| Download: ML13330A381 (12) | |
Text
Southern California Edison Company P.0.
BOX 800 4WALNUTGROVEAVENUE RO EMEAD. CALIFORNIA 91770 W. C. MOODY TELEPHONES MANAGER, NUCLEAR LICENSING August 18, 1981 (213) 572-1817 (213) 572-1806 Director, Office of Nuclear Reactor Regulation 4
tl, 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 VI-7.B San Onofre Nuclear Generating Station Unit 1 Your letter of March 4, 1981, requested additional information for your evaluation of SEP Topic VI-7.B, ESF Switchover From Injection to Recirculation Mode.
The requested information is provided as an enclosure to this letter.
If you have any questions on this information, please let us know.
Very truly yours, Enclosure 8108200403 91081 '
PDR ADOCK 05000206, P
PIR'
ENCLOSURE INFORMATION FOR SEP TOPIC VI-7.B SAN ONOFRE UNIT 1 Item 1 For each instrument, indicator, logic device and alarm that is used by the operator to perform a manual function in the switchover sequence; describe how that device is qualified and installed (e.g., independence and separation of circuits) as Class 1E equipment.
Response
There are four indicators in the control room which are used by the operators in terminating safety injection and initiating recirculation. These indications are containment sphere sump level indication (LC/LI-951),
containment sphere sump high-high level alarm (LS-73), refueling water storage tank (RWST) level indication (LT/LI-950), and RWST low-low level alarm (LS-69).
In addition, as discussed in Item E below, new containment sump level instrumentation is being installed in connection with the implementation of TMI related requirements.
Each of these instruments is discussed in the following paragraphs.
A. Containment Sphere Sump Level Indication (LC/LI-951)
Level element, LC-951, consists of a Gems LS-800 float type sensing unit which activates magnetic reed switches housed inside a stainless steel stem. The device utilizes six floats along the stem height to monitor the water level from elevation -10 to 0 ft.
The level element assembly is bolted to the primary shield wall.
The control room indicator, LI-951, consists of seven indicating lights mounted on vertical control board C09. The lights are lit progressively upon initiation by the float activated magnetic reed switches in containment as the water level rises. The lights indicate level in two foot increments from elevation -10 to 0 feet.
As discussed in SCE's submittal to the NRC dated October 31, 1980, documentation is not available to demonstrate that LC-951 is qualified to operate in the post-accident environment. The electrical circuitry associated with this instrument is aligned with Train A. However, the separation of cable routing from Train B or non-safety related circuits has not been determined.
B. Containment Sphere High-High Level Alarm (LS-73)
Level Switch LS-73 is a Magnetrol Model No. A-153-F. The setpoint for the alarm from this level switch is at elevation -3 feet. The level switch is mounted on the primary shield wall.
Similar to Item A above, as discussed in SCE's submittal to the NRC dated October 31, 1980, documentation is not available to demonstrate that LS-73 is qualified to operate in the post-accident environment.
The electrical circuitry associated with this instrument is aligned with Train A. However, the separation of cable routing from Train B or non-safety related circuits has not been determined.
-2 C. RWST Level Indication (LT/LI-950)
Level transmitter, LT-950, is a Foxboro pneumatic instrument which provides a 3 to 15 psi signal to the control roomm indicator via instrument tubing.
The indicator, LI-950, is mounted on vertical board C09.
LI-950 is a Hays Republic Model 5B pneumatic indicator.
In light of the fact that these instruments are pneumatic, they have not been reviewed as part of the evaluation of the environmental qualification of electrical equipment.
However, since the environment in which these instruments are located will be non-harsh (i.e., outside and control room) when they are required to operate, they are expected to be operable based on the operating experience with these instruments over the last 13 years.
D.
RWST Low-Low Level Alarm (LS-69)
LS-69 is a Magnetrol Model No. 751-VPX level switch. The setpoint for the alarm is at elevation 22'-6".
Since this instrument is located outside, and therefore, in a non-harsh environment, it's qualification has not been evaluated to-date as part of the environmental qualification of electrical equipment. However, based on the operating experience of this instrument over the last 13 years, it is expected that it will be operable when required.
The electrical circuitry associated with LS-69 is aligned with Train A.
However, since the cable routing was determined in the field, there is no record of the actual cable routing.
Therefore, separation from Train B or non-safety related circuits has not been determined.
E.
New Containment Sump Level Indication In connection with the implementation of TMI related requirements, new containment sump level instrumentation is being installed. This instrumentation will consist of two transmitter-indicator loops to provide continuous indication in the control room of containment water level from elevation -10 feet to +12 feet. These instruments will be used to replace the functions of LC/LI-951 and LS-73.
Each of the two new loops will consist of two water level transmitters with receiver power supplies and board mounted indicators powered by two physically separated and independent Class 1E channels. The transmitters will be DeLaval/Gems Type XM-54852 and XM-54853, the receiver power supplies will be Gems Model RE-36562, and the board mounted indicators will be Sigma Model 9270-20-D-VB.
-3 Each level transmitter will be composed of three float type sensing units connected in series to cover containment water level from elevation -10 feet to +12 feet.
One of the three units will cover from -10 feet to
-2 2/3 feet, the second unit from -2 2/3 feet to +4 2/3 feet and the third from +4 2/3 feet to +12 feet.
All transmitters will have lead wire protecting piping which extends above their respective watertight junction boxes to a common junction box above the +12 foot level.
The power supply-receiver and indicators will be mounted in the control room. The indicators will have a single alarm set point.
The new Gems level elements and power supply - receivers are to undergo a qualification program in 1981 to qualify these devices in accordance with IEEE-323-1974 and IEEE-344-1975. The new Sigma level indicators have been qualified in accordance with IEEE-323-1971 and IEEE-344-1971.
The power source for the receiver units and the indicators located in the control room will be supplied from the 120 VAC vital buses.
New conduit and cable will be installed between each level transmitter in containment and the control room. For all newly installed equipment, separation of redundant power sources and circuits will be maintained as a minimum up to any interface with existing equipment.
Item 2 Describe the paths of the minimum flow lines from each ECCS pump discharge to the line end. This description should identify all valves in these lines, the signals that control each valve, the power sources for each valve, and the qualification of each valve.
Response
Recirculation is initiated by the operator after the core has been covered with borated water by the safety injection system and after a sufficient quantity of water has accumulated in the containment sphere sump to provide NPSH for the recirculation pumps. The recirculation pumps take spilled water from the containment sphere sump and pump it through the recirculation heat exchanger to the charging pumps which return the water to the Reactor Coolant System (RCS) via the reactor coolant pump seal water injection lines.
Containment sphere spray is provided by the refueling water pumps. During the recirculation mode, the recirculation pumps are used to supply water to the refueling water pumps for containment spray.
The hot leg recirculation system provides an additional means of adding borated water to the RCS, by use of the charging pumps and the pressurizer auxiliary spray header. The charging pump discharge is directed through CV 305 to the loop B hot leg of the RCS.
-4 The normal flow paths outside containment of the above described systems (recirculation, containment spray and hot leg recirculation) as well as associated lines which are pressurized during recirculation are marked up in yellow on the attached Piping & Instrumentation Drawings (P&ID's) 568769-15 Safety Injection System 568767-20 Chemical and Volume Control System 568776-21 Miscellaneous Water Systems Minimum flow lines (i.e., lines connected to the recirculation, containment spray or hot leg recirculation lines which are not associated with the normal flow paths of these lines) outside containment are marked up in blue on the same attached P&ID's. These lines are identified to the first normally closed manual valve or to the second isolation valve as appropriate. The non-manual isolation valves are listed in Table 1 along with the power source, elementary diagram, and failure mode of each valve.
Control signals for these valves are shown on the elementary diagramscopies of which are enclosed. As can be seen from the attached P&ID's, the minimum flow lines are generally associated with the refueling water storage tank, the normal chemical and volume control system components and various sample lines. The environmental qualification of all valves on Table 1 except CV's 334, 406A and 406B was addressed in SCE's submittal to the NRC dated May 18, 1981. CV 334 is located outside in a non-harsh environment and is considered qualified by experience. CV's 406A and 406B are located in the charging pump room. At the time these valves are required to close (i.e., during the safety injection phase) this room will be at ambient conditions, and therefore, these valves are expected to close based on experience.
Item 3 For each minimum flow line that returns to a point other than the pump intake point, provide a single failure analysis and quantify the offsite dose rate, dose, and dose assumptions obtaining from all single failures that do not isolate these lines during the recirculation phase of ECC.
Response
An analysis of the failure to close the isolation valves in each of the minimum flow lines identified in blue on the attached P&ID's is provided in Table 2. Based on this single failure analysis, it is concluded that only one postulated failure will result in recirculated fluid being discharged to a location other than the RCS and spray lines inside containment. The one case is the postulated failure of the spring loaded check valve 256 on line 2010-1/2"-151R. This valve will open at a pressure of 75+ 7.5 psig allowing flow to go back to the volume control tank. During the recirculation mode, the pressure in this line will be less than 65 psig, which is the discharge pressure of the recirculation pumps, and therefore, this valve is not expected to open. In the event the valve fails open, flow would be diverted to the volume control tank at an initial flow rate of about 14 gpm. As the tank fills the increase in pressure of the hydrogen blanket will reduce the flow to 6 gpm at a pressure of 55 psig. At a pressure of 55 psig, relief valve RV 226
-5 will open and a flowrate of 6 gpm will be maintained to the volume control tank and on to the flash tank. Assuming an initial tank level at the high level alarm setpoint, it will take approximately 65 minutes to reach the setpoint of RV 226. During this time, the operator would be alerted to the increase in level in the volume control tank by LT 1100 which alarms at 48%,
and would have sufficient time to take corrective action. Therefore, it is not postulated that this path will contribute to the post-accident offsite dose.
Consideration of the doses due to leakage from the recirculation system has been analyzed in SCE's letter to the NRC dated March 24, 1977. In accordance with Technical Specification 3.3.1, recirculation loop leakage is limited to less than 625 cc/hr.
TABLE 1 NON-MANUAL ISOLATION VALVES IN RECIRCULATION SYSTEM Valve Power Elementary Diagram Failure Mode MOV 883 MCC 3 64374-4 As is MOV/LCV MCC 2A 5151028-5 with CCN 10 As is 1100C MOV 880 MCC 2 455371-2 As is CV 334 120 VAC 455454-2 Open on Loss of Power or Air Vital Bus 4 CV 406B 120 VAC 455875-0 Open on Loss of Power; Utility Bus Closed on Loss of Air CV 406A 120 VAC 455875-0 Closed on Loss of Power, Open on Loss of Air*
Utility Bus CV 410 120 VAC 455437-3 with CCN 4 Closed on Loss of Power or Vital Bus 4 Air CV 411 120 VAC 455437-3 Closed on Loss of Power or Vital Bus 4 Air CV 528 Vital Bus 2 (solenoid) 64353-3 with CCN 4 Closed on Loss of Power MCC 2A (motor) 64371-4 with CCN 6 CV 527 Vital Bus 1 (solenoid) 64350-3 with CCN 5 Closed on Loss of Power MCC 1 (motor) 64362-5 with CCN 6 Note:
Elementary diagram 455875-0 incorrectly shows solenoid configuration for CV 406A.
Page 1 TABLE 2 SINGLE FAILURE ANALYSIS OF ISOLATION VALVES IN RECIRCULATION SYSTEM Reference P&ID Compensating Effect of Valve Location Provision Failure Remarks MOV 568769 568776 Check Valve 276 None 883 C-13 F-4 Check Valve 568769 568776 MOV 883 None 276 C-13 F-4 Block Valve 568769 None required. Normally NA T42 C-13 closed manual valve.
Sample 568769 None required. Normally NA Valve G-10 closed manual valve.
Drain 568769 None required. Normally NA Valve G-9 closed manual valve.
Check Valve 568769 568767 MOV/LCV 1100 C None Additional valve MOV/LCV 236
.F-9 F-7 1100 E shown on P&ID is not yet installed.
MOV/LCV 568769 568767 Check Valve 236 None Additional valve MOV/LCV 1100 C F-9 E-7 1100 E shown on P&ID is not yet installed.
Check Valve 568769 Relief Valve 882 None 881 F-5 MOV 568769 Relief Valve 882 None 880 E-6 CV 568767 Check Valve 335 None 334 H-8
Page -2 Reference P&ID Compensating Effect of Valve Location Provision Failure Remarks Check Valve 568767 CV 334 None 273 H-8 Check Valve 568767 Manual Valve X42D None 337 G-8 Manual Valve 568767 None required. Normally NA X42D G-8 closed manual valve.
Manual Valve 568767 Manual Valve 407 None 407 F-7 Manual Valve 568767 Manual Valve 407 None 407 G-7 Manual Valve 568767 Manual Valve 407 None 407 F-8 Manual Valve 568767 None required. Normally NA 344 E-8 closed manual valve.
Check Valve 568767 Manual Valve 348 None 349 F-7 Manual Valve 568767 None required. Normally NA 348 F-7 closed manual valve.
CV 568767 Check Valve 343 None 406B E-7 Check Valve 340 Manual Valve 982 CV 406A Manual Valve 980
Page -3 Reference P&ID Compensating Effect of Valve Location Provision Failure Remarks Check Valve 568767 Manual Valve 344 None 343 E-8 CV 406B Check Valve 568767 Manual Valve 344 None 340 E-8 CV 406B Manual Valve 568767 None required. Normally NA 982 E-7 closed manual valve.
CV 406A 568767 CV 406B None E-7 Manual Valve 568770 None required. Normally NA 980 F-9 closed manual valve.
Manual Valve 568770 None required. Normally NA 964 F-10 closed manual valve.
CV 568767 CV 411 None 410 D-6 CV 568767 CV 410 None 411 D-6 Block Valve 568767 None required. Normally NA E-5 closed manual valve.
Relief Valve 568767 None required. Relief NA 289.
D-4 valve.
CV 568767 CV 527 None 528 C-4 CV 568767 CV 528 None 527 C-4
Page -4 Reference P&ID Compensating Effect of Valve Location Provision Failure Remarks Relief Valve 568767 None required. Relief NA 258 G-5 Valve.
Manual Valve 568767 None required. Normally NA 233 E-6 closed manual valve.
Spring Loaded 568767 None. Spring loaded Water returned Downstream locked open Check Valve F-6 to 75+ 7.5 psig to Volume Control globe valve can be 256 Tank manually closed Drain Valve 568767 None required. Normally NA X58N F-6 closed manual valve.
Drain Valve 568767 None required. Normally NA X58N G-6 closed manual valve.
Drain Valve 568767 None required. Normally NA X58N H-5 closed manual valve.
Block Valve 568776 None required. Normally NA D-7 closed manual valve.
Block Valve 568776 None required. Normally NA E-7 closed manual valve.
Block Valve 568776 None required. Normally NA E-7 closed manual valve.
Block Valve.
568776 None required. Normally NA 152 F-7 closed manual valve.
Block Valve 568776 None required. Normally NA 142 D-7 closed manual valve.
Drain Valve 568776 None required. Normally NA F-5 closed manual valve.
Page -5 Reference P&ID Compensating Effect of Valve Location Provision Failure Remarks Block Valve 568776 None required. Normally NA 25 F-4 closed manual valve.
Block Valve 568776 None required. Normally NA F-5 closed manual valve.
Block Valve 568776 None required. Normally NA F-5 closed manual valve.
Block Valve 568776 None required. Normally NA 54 G-5 closed manual valve.
Block Valve 568776 None required. Normally NA G-4 closed manual valve.
Block Valve 568776 None required. Normally NA 183 G-5 closed manual valve.
Block Valve 568776 None required. Normally NA 76 G-4 closed manual valve.
Check Valve 568777 Pump G-200B None 237 G-12 Relief Valve 2003 B Manual Valve 568777 None Required. Normally NA 132 G-12 closed manual valve.
Relief Valve 568777 Check Valve 237 None 2003 B G-12 Check Valve 568777 Pump G-200 A None 237 H-12 Relief Valve 2003 A Manual Valve 568777 None required. Normally NA 132 H-12 closed manual valve.
Relief Valve 568777 Check Valve 237 None 2003 A H-12