ML13310A926
| ML13310A926 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 09/01/1983 |
| From: | Morgan H SOUTHERN CALIFORNIA EDISON CO. |
| To: | |
| Shared Package | |
| ML13310A925 | List: |
| References | |
| 0618G-NAB, 618G-NAB, SO1-4-33, TAC-44128, NUDOCS 8309070176 | |
| Download: ML13310A926 (13) | |
Text
SAN ONOFRE NUCLEAR GENEOING STATION OPERATIN*5STRUCTIOv 501-4-33 UNIT 1' PRIMARY PLANT EFFECTIVE DATE REVISION 0 PAGE 1 POST ACCIDENT RCS VENT SYSTEM OPERATION TABLE OF CONTENTS SECTION PAGE 1.0 OBJECTIVE 2
2.0 REFERENCES
2 3.0 PREREQUISITES 2
4.0 PRECAUTIONS 3
5.0 CHECK-OFF LIST(S) 4 6.0 INSTRUCTION 4
6.1 Gaseous Void Size Determination 4
6.2 Attempt to Recombine Condensible Gases 4
6.3 Reactor Vessel Head Venting 5
6.4 Pressurizer Venting 9
7.0 RECORDS 10 8.0 ATTACHMENTS 10 8.1, RCS Gaseous Void Detection and Sizing (2 pages) 8.2, Venting Time Period (2 pages)
PAGES CHANGED WITH THIS REVISION:
NEW PREPARED BY:
PROCEDURE WRITER DATE APPROVED BY:
H. E. MORGAN DATE MANAGER, OPERATIONS 0618g/nab S8309070176 _8309017 1 PDR ADOCK 05000206 PDR
SAN ONOFRE NUCLEAR GEN ING STATION OPERATIN WSTRUCTIO 501-4-33 UNIT 1' PRIMARY PLANT REVISION 0 PAGE 2 POST ACCIDENT RCS VENT SYSTEM OPERATION 1.0 OBJECTIVE 1.1 The objective of this Instruction is to provide guidance on Operating the Reactor Coolant System.
1.1.1 Removing and restoring power to the vent valves; 1.1.2 Gaseous void size determination; 1.1.3 Attempt to recombine condensible gases; 1.1.4 Venting non-condensible gases from the Reactor Vessel Head through the Reactor Coolant Venting System; 1.1.5 Venting non-condensible gases from the Pressurizer through the Reactor Coolant Venting System.
2.0 REFERENCES
2.1 SO1-1.0-10, Reactor Trip or Safety Injection 2.2 SO1-4-25, Ventilation System Operation 2.3 SO1-5-11, Post Accident Hydrogen Gas Control 2.4 P&ID 568766, Reactor Coolant System.
2.5 Elementary Diagram 5180607, Reactor Coolant System Vent Valves, Train A 2.6 Elementary Diagram 5180608, Reactor Coolant System Vent Valves, Train B 2.7 Background Information for Westinghouse Emergency Response Guidelines, FR-I.3, Void in Reactor Vessel, Basic Revision, Westinghouse Electric Corporation; September 1981 2.8 Response to Void in Reactor Vessel, FR-1.3, Basic Revision, Westinghouse Electric Corporation; September, 1981 2.9 Reactor Coolant Venting System, Controls Description, WP 3.2 SONGS 1, TMI Phase II; February, 1981 3.0 PREREQUISITES 3.1 Check that this copy of the Instruction is up-to-date against a controlled copy and review all applicable Temporary Change Notices (TCN's).
SAN ONOFRE NUCLEAR GEN
- ING STATION OPERATIN NSTRUCTIONh S01-4-33 UNI.T 1' PRIMARY PLANT REVISION 0 PAGE 3 3.0 PREREQUISITES (Continued) 3.2 Prior to venting, the Hydrogen Recombiners should be in service per 501-5-11, Post Accident Hydrogen Gas Control.
3.3 This Instruction is to be used if any one or a combination of the symptoms outlined herein indicate the presence of a gaseous void in the RCS.
3.3.1 Variations from normal Pressurizer pressure and level response during normal charging and spraying operations (Pressurizer level may decrease during a charging operation and level may rise rapidly during a spraying operation);
3.3.2 An indication of Reactor Vessel Head temperatures equal to or greater than saturation temperature; 3.3.3 Gases in the RCS resulting from several types of events:
A core uncovering; or, a rapid RCS Cooldown resulting in vessel head temperature greater than the primary system saturation temperature.
3.3.4 Ineffectiveness of Pressurizer Spray to reduce RCS pressure.
3.3.5 The Control Room Operator otherwise determines that a non-condensible void exists in the Pressurizer.
3.4 RCS pressure and hot leg temperature must be stable with Pressurizer level stable between 40% and 60% prior to performing this Instruction.
3.5 The reactor is tripped and safety injection is not in operation.
4.0 PRECAUTIONS 4.1 Reactor Coolant System stabilization, constant Pressurizer level, and adequate reactor coolant subcooling are required during venting operations to ensure that adequate core cooling is maintained.
4.2 It is assumed in this Instruction that the Containment Sphere temperature is near the value expected during normal operating conditions. Therefore, the Pressurizer level and pressure requirements throughout this Instruction do not include error allocations due to an adverse Containment environment. It is advised that consideration be given to these values if Containment atmospheric conditions deviate from normal.
4.3 The Reactor Coolant Venting System is not designed for, and should not be used as, the primary means of mitigating an inadequate core cooling event.
4.4 The venting operation may result in RCS gases being vented to the Containment. All available air circulation equipment should be maintained in operation to prevent concentrated hydrogen pockets from forming.
SAN ONOFRE NUCLEAR GENE ING STATION OPERA TIG@STRUCTION 501-4-33 UNIT 1*
PRIMARY PLANT REVISION 0 PAGE 4 4.0 PRECAUTIONS (Continued) 4.5 If venting to the Containment Sphere atmosphere, the maximum allowable time period for venting should be determined to limit the hydrogen concentration to less than 3 volume percent to prevent a potentially explosive situation.
4.6 Reactor subcooling margin should be increased to 90 0F to ensure that reactor subcooling will be maintained over the entire range of RCS operating conditions, if the venting operation is terminated following a 200 psi decrease in RCS pressure.
4.7 Do not open the Pressurizer and Reactor Vessel Head Vents at the same time.
5.0 CHECK-OFF LISTS 5.1 None 6.0 INSTRUCTION 6.1 Gaseous Void Size Determination 6.1.1 Determine the size of the gaseous void per, RCS Gaseous Void Detection and Sizing.
.1 If immediate venting is necessary, this calculation is not required. Proceed to step 6.3.
.2 When void size is determined, proceed to step 6.3.
CAUTION Do not trip any running, or start any non-operating, Reactor Coolant Pump during the performance of the following actions unless directed otherwise within this procedure.
6.2 Attempt to Recombine Condensible Gases CAUTION Increased charging flow, with condensible gases in the
- RCS, may result in a decreasing Pressurizer level.
Maintain pressurizer level greater than 20%.
6.2.1 Terminate any changes to the RCS that may be in progress and bring the RCS to as close to a steady state condition as possible.
SAN ONOFRE NUCLEAR GEN IN STATION OPERATIN ST UCTION SO1-4-33 UNIT 1 PRIMARY PLANT REVISION 0 PAGE 5 6.0 INSTRUCTION (Continued) 6.2.2 Verify that Pressurizer level is between 40% and 60%.
6.2.3 Turn on the Pressurizer backup heaters to increase RCS pressure by 50 psi.
.6.2.4 Adjust charging and letdown flow rate as necessary to maintain a constant Pressurizer level.
6.2.5 If Pressurizer level falls below 20%, turn OFF Pressurizer Heaters and return to step 6.3.2.
6.2.6 If Pressurizer level cannot be maintained greater than 10%; or, RCS pressure is decreasing in an uncontrolled manner:
.1 Manually initiate SI;
.2 Proceed to S01-1.0-10, Reactor Trip or Safety Injection.
6.2.7 If increasing RCS pressure is successful in recombining the condensible gases in the RCS (as indicated by a return to normal response in those parameters used to determine the presence of the void), return to the appropriate Operating Instruction.
.1 If this step is not successful in eliminating the gaseous void, continue with this Instruction.
6.3 Reactor Vessel Head Venting 6.3.1 Prepare the Containment for venting.
.1 Verify Containment Purge isolated.
.2 Verify Containment Exhaust isolated.
.3 Start all available Containment air circulation equipment in accordance with S01-4-25, Ventilation System Operation.
.4 If venting directly into the containment, determine the maximum allowable time period for venting per, "Venting Time Period."
6.3.2 Venting the RCS may result in RCS pressure decreasing below the SI point. To prevent an unwanted SI initiation:
.1 Manually block Low Pressure SI initiation if the permissive is energized.
6.3.3 To ensure that RCS subcooling will be maintained during the venting operation, increase RCS subcooling to 900F by:
SAN ONOFRE NUCLEAR GEN TING ST ATI O OPERATII*
NSTRUCTION S01-4-33 UNIT 1 PRIMARY PLANT REVISION 0 PAGE 6 6.0 INSTRUCTION (Continued) 6.3.3.1 Increasing RCS pressure with Pressurizer heaters (preferred); and/or
.2 Decreasing RCS temperature by dumping steam.
6.3.4 To maintain RCS mass inventory during venting, increase Pressurizer level to greater than 50%:
.1 Isolate letdown (to remain isolated during venting operation);
.2 Increase charging flow until level reaches 50%.
6.3.5 Limit Pressurizer level decrease during venting:
.1 Increase charging flow to the maximum limit.
.2 Start a second charging pump..
6.3.6 Begin venting operation.
CAUTION If a loss of all RCPs occurs, the venting operation should continue to allow natural circulation to become established.
NOTE:
Venting to the Pressurizer Relief.Tank (PRT) is preferred if the amount to be vented is expected to be small and the rupture disc is intact.
NOTE:
Opening any one (1) of the vent valves will actuate an alarm on the Auxiliary Feedwater Panel indicating that the valve has been energized to open.
.1 To vent from the Reactor Vessel Head to the PRT:
.1.1 Actuate the Train B master power pushbutton, HS-3212A.
NOTE:
ON status is indicated by a RED light. OFF status is indicated by a GREEN light.
.1.2 OPEN SV-3401, Reactor Vessel Head Vent block valve.
SAN ONOFRE NUCLEAR GEN*ING STATION OPERATIN#STRUCTION 01-4-33 UNIT 1' PRIMARY PLANT REVISION 0 PAGE 7 6.0 INSTRUCTION (Continued) 6.3.6.1.3 IF SV-3401 fails to open, use Train A block valve by actuating the Train A master switch, HS-2210A and OPEN SV-2401.
.1.4 OPEN SV-3402, Reactor Vessel Head Vent valve.
.1.5 Proceed to step 6.4.6.3.
NOTE:
Venting of the Reactor Vessel Head to the Pressurizer Relief Tank has commenced.
.2 To vent from the Reactor Vessel Head directly into the Containment:
.2.1 DEPRESS the Train A master power pushbutton, HS-2210A.
NOTE:
ON status is indicated by a RED light.
OFF status is indicated by a GREEN light.
.2.2 OPEN SV-2401, Reactor Vessel Head Vent block valve.
.2.3 IF SV-2401 fails to open; use Train B block valve by actuating the Train B master switch, HS-3212A and OPEN SV-3401.
.2.4 OPEN SV-2402, Reactor Vessel Head Vent valve.
NOTE:
Venting of the Reactor Vessel Head'into the Containment has.commenced.
.3 Monitor the trend of Pressurizer level on the Technical Support Center computer (see SO1-LATER). If the computer is not available, manually record the trend information for analysis. The following conditions will determine the probable status of the RCS when venting from the Reactor Vessel Head:
.3.1 Increasing Pressurizer level - Gaseous voids exist in the RCS other than in the Reactor Vessel Head or Pressurizer.
.3.2 Constant Pressurizer level - No significant gaseous voids exist in the RCS.
.3.3 Decreasing Pressurizer level - A gaseous void exists in the Reactor Vessel Head or Pressurizer.
SAN ONOFRE NUCLEAR GEN*ING STATION OPERATIN*#STRUCTION 501-4-33 UNIT 1' PRIMARY PLANT REVISION 0 PAGE 8 6.0 INSTRUCTIONS (Continued) 6.3.7 Terminate the venting operation by closing the vent isolation and block valves when:
.1 Containment Hydrogen concentration increases to greater than 3% by volume.
.2, Time period determined in step 6.4.1.4 elapses; OR
.3 Pressurizer pressure decreases by 200 psi; OR
.4 Reactor coolant subcooling decreases below 400F; OR
.5 Pressurizer level decreases below 20%;
.6 If, while venting to the PRT, the rupture disc is breached; OR
.7 Reactor Vessel Head is refilled as indicated by a decrease in the rate of depressurization or a change in the rate of Pressurizer level trend.
6.3.8 Restore Pressurizer water level to the operating range.
.1 Re-establish normal charging flow.
.2 Re-establish normal letdown flow.
6.3.9 Determine the hydrogen concentration inside the Containment.
.1 If the hydrogen concentration is equal to or greater than 3 volume percent, the concentration must be reduced prior to reopening the RCS Vents.
Refer to S01-5-11, Post Accident Hydrogen Gas Control, for appropriate instruction.
6.3.10 Evaluate the response of Pressurizer level trend, recorded in 6.4.6.3, to determine if a gaseous void existed in the Reactor Vessel Head.
SAN ONOFRE NUCLR ENE ING T TON OPERATIN STRUCTION SO-4-33 UNIT 1 PRIMARY PLANT REVISION 0 PAGE 9 6.0 INSTRUCTIONS (Continued) 6.3.10.1 Of a gaseous void existed and venting was terminated prior to the Reactor Vessel Head being completely filled, return to 6.4.1.
6.3.11 Return to the appropriate Operating Instruction following the successful completion of RCS venting.
6.4 Pressurizer Venting 6.4.1 Prepare the Containment for venting.
.1 Verify Containment purge isolated.
.2 Verify Containment exhaust isolated.
.3 Start all available Containment air circulation equipment.
.4 If venting directly into the containment, determine the maximum allowable time period for venting per, "Venting Time Period."
6.4.2 To vent from the Pressurizer to the PRT:
.1 Actuate the Train B master power pushbutton, HS-3216A.
NOTE:
ON status is indicated by a RED light; OFF status is indicated by a GREEN light.
.2 Open SV-2403, Pressurizer Vent Block Valve.
.3 If SV-3403 fails to open, use the Train A Block Valve by actuating the Train A master power pushbutton, HS-2214A; and OPEN SV-3403.
.4 OPEN SV-2404, Pressurizer Vent Valve.
NOTE:
Venting of the Pressurizer to the PRT has commenced.
.5 Proceed to step 6.5.4.
6.4.3 To vent from the Pressurizer to the containment:
.1 Actuate the Train A master power pushbutton, HS-2214A.
NOTE:
ON status is indicated by a RED light; OFF status is indicated by a GREEN light.
SAN ONOFRE NUCLEAR GEN TING STATION OPERATINONSTRUCTION 501-4-33 UNIT 1 PRIMARY PLANT REVISION 0 PAGE 10 6.0 INSTRUCTIONS (Continued) 6.4.3.2 OPEN SV-3403, Pressurizer Vent Block Valve.
.3 If SV-3403 fails to open, use the Train B Block Valve by actuating the Train B master power pushbutton, HS-3216A, and OPEN SV-2403.
NOTE:
Venting of the Pressurizer to the containment has commenced.
6.4.4 Terminate venting operation by closing the vent isolation and block valves when:
.1 RCS pressure is at saturation pressure for Pressurizer temperature.
7.0 RECORDS 7.1 Completed copies of Attachment 1 and 2 shall be placed in the Outage File and transmitted to CDM.
8.0 ATTACHMENTS 8.1, RCS Gaseous Void Detection and Sizing (2 pages) 8.2, Venting Time Period (2 pages) 0618g
SAN ONOFRE NUCLEAR GENEO NG STATION OPERATINSTRUCTION 501-4-33 UNIT 1 REVISION 0 PAGE 1 OF 2 ATTACHMENT 1 RCS GASEOUS VOID DETECTION AND SIZING
- 1. Achieve a constant pressurizer level and pressure condition.
- 2.
Place the RCS wide range pressurizer pressure and the pressurizer level on trend recorders. The recorder scale should be 150 psig pressure and 10% of span for level.
- 3. Record the following parameters.
RCS Pressure
=
PSI Seal Injection Flow = __
GPM PZR Level PSI Seal Leakoff Low
=
GPM Charging Rate
=
GPM
- 4.
Isolate the RCS letdown flow, turn off all pressurizer heaters, and terminate the pressurizer spray by placing the spray control in manual and zeroing the demand signal.
Record Time:
- 5. Allow the RCS charging flow to either increase RCS pressure 100 psi or increase pressurizer level 5% of span.
- 6. Record the RCS pressure, pressurizer level and time.
RCS Pressure
=
_ __PSI Time
=_
GPM.
PZR Level
=
- 7.
Reinitiate RCS letdown flow and restore normal pressurizer pressure and level control.
- 8.
Calculate the initial and final pressurizer vapor-space volumes.
Initial Vapor Volume =
(1-PZR Level % X Total Cylindrical PZR Volume FT3 )+
(Upper Spherical Volume FT')
=
(1-PZR Level % X 1224 FT3) + (76 FT3 )
=_FT 3
Final Vapor Volume
=
(Init. Vapor Vol.) -
(A PZR Level % X Total Cylindrical Vol.)
=
(Init. Vapor Vol.) - (A PZR Level % X 1224 FT 3 )
=_FT 3
SAN ONOFRE.NUCLEAR GENEOING STATION OPERATiN*5STRUCTION S01-4-33 UNIT 1' REVISION 0 PAGE 2 OF 2 ATTACHMENT 1 RCS GASEOUS VOID DETECTION AND SIZING
- 9.
Determine the total volume charged into the RCS.
Volume Charged = (Charging + Seal Injection -
Seal Leakoff GPM) X (Time) X 1
)
7.45 GPM/FT3
=_FT 3
- 10.
Determine the expected pressurizer level change.
Expected A level
= (Charging Volume FT') X (
100%
)
Total PZR Volume FT3
= (Charging Volume FT') X (
100%
)
1300 FT3
- 11.
If the actual presurizer level change is less than the expected level change, then a gaseous void exists in the Reactor Coolant System. Perform the following step to determine the volume of the RCS void.
- 12.
The initial and final RCS gaseous void volumes can be calculated from the following equations.
Initial RCS Void =
(Initial Vapor Volume) -
(Final Vapor Volume + (Volume Charged)
(1 -
Initial Pressure)
Final Pressure
=
FT3 Final RCS Void
= (Initial RCS Void) X (Initial Pressure)
(Final Pressure)
FT3 PERFORMED BY:
DATE REVIEWED BY:
DATE Shift Supervisor
SAN ONOFRE NUCLEAR GENE ING STATION OPERATINA STRUCTION S01-4-33 UNIT 1*
REVISiON 0 PAGE 1 OF 2 ATTACHMENT 2 VENTING TIME PERIOD
- 1. Convert the containment free-volume to containment volume at standard temperature and pressure conditions.
Cont. Volume (STP) = (Cont. Volume FT') X (Cont. Pressure**) X (
492'R )
14.7 PSIA Cont. Temp*
= (1,200,000 FT') X (Cont. Pressure**) X (
492'R )
14.7 PSIA Cont. Temp*
=
_FT 3
Temperature in degrees Rankine (IF + 460)
If containment pressure has increased above 14.7 psia then use 14.7 psig as pressure for conservatism.
- 2. Determine the containment hydrogen concentration in volume percent units.
NOTE:
The containment hydrogen concentration will be insignificant if there has been no leakage from the RCS to the containment.
- 3. Calculate the maximum hydrogen volume that can be vented to the containment which will result in a containment hydrogen concentration of less than or equal to 3 volume percent.
Maximum H2 Volume =
to be Vented (3.0% -
Cont. H2 Concentration %) X (Cont. Volume [STPl) 100%
=_FT 3
- 4.
From Page 2 (RCS Pressure vs. H2 Flow Rate) determine the allowable venting period which will limit the containment hydrogen concentration to 3 volume percent.
Venting Period = Max. H2 Vented (From step 3)
H2 Flow Rate
=_
Mins.
PERFORMED BY:
DATE REVIEWED BY:
DATE Shift Supervisor