ML19344E476
| ML19344E476 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 08/18/1980 |
| From: | Mills L TENNESSEE VALLEY AUTHORITY |
| To: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| IEB-80-06, IEB-80-6, NUDOCS 8009020104 | |
| Download: ML19344E476 (6) | |
Text
7 7c2 TENNESSEE VALLEY,c 1N C P q;.;
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AQTHORITY CH ATTANOOGA, TENNE'55EE 37 doi 400 Chestnut Street Tower II Nk/sD@g198g,.]q Mr. J. P. O'Reilly, Director Office of Inspection and Cnforcement
,U.S. Nuclear Regulatory Commission Region II - Suite 3100 101 Marietta Street Atlanta, Georgia 30303
Dear Mr. O'Reilly:
OFFICE OF ION AND ENFORCEMENT BULLETIN 80 RII:JP 50-327 SEQUOYAH NUCLEAR PLANT UNIT 1 In response to your letter dated March 13, 1980, which transmitted IE Bulletin 80-06 on Engineered Safety Features (ESP) Reset Controls, we submitted preliminary results of our investigation for Sequoyah unit 1 on June 12, 1980, and our first progress report on July 14, 1980.
Enclosed is a table which identifies all components identified by drawing review which do not remain in their emergency mode after reset of an ESF signal. We have evaluated the impact on safety of each of these components and determined, as indicated on the tabla, that no items will require raodifications to comply with the intent of the bulletin.
We have completed testing of the ESF Actuation Systen reset controls.
The test results are under review to determine if any additional co=ponents do not remain in their emergency mode after reset of an ESF signal. We expect to submit a report covering the test results by August 29, 1980.
L Very truly yours, TENNESSEE VALLEY AUTHORITY L. M. Mil s, Ma ger Nuclear Regulation and Safety Sworn to and subscribed before is /
day of
@s1980 me AM NotargPublic
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g My Commission Expires
'/!8 L' Enclosure cc: See page 2
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8009020l04 An Equal Opportunity Employer
-2 Mr. J. P. O'Reilly, Director August 18, 1980 cc: Director, Division of Reactor Operations Inspection (Enclosure)
Office of Inspection and Enforcement
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U.S. Nuclear Regulatory Commission Washington, DC 20555 1
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e ENCLOSURE SEQUOYAll NUCLEAR PLANT UNIT 1 TABLE A-1 EQUIPMENT Wl!ICli DOES NOT REMAIN IN Tile EMERGENCY MODE AFTER RESET OF ' file ESF SIGNAL Equipment Number Function Discussion FCV-3-35A SG 1 Inlet Flow Cont V1v flypass Vlv These receive one train of reactor trip or the same train of safet FCV-3-48A SG 2 injection. A safety injection signal gives a teactor trip so the FCV-3-90A SG 3 safety injection is " scaled in" by reactor trip and both must be FCV-3-103A SG 4 reset to reopen the valve.
g FCV-3-35 SG 1 FW Inlet Flow Control Viv These receive both trains of reactor trip or safety injection. A FCV-3-48 SG 2 safety injection signal gives a reactor trip so the safety FCV-3-90 SG 3 injection is " scaled in" by reactor trip and both trains and both FCV-3-103 SG 4 signals must be reset to open the valves.
LCV-3-172 SG 3 Level Control V1v These valves are allowed to modulate when the turbine driven LCV-3-173 SG 2 auxiliary feed pump is running. Reset of an ESF signal does not LCV-3-174 SG 1 affect whether the valve can modulate.
LCV-3-175 SG 4 LIC-3-172 SG 3 Level Indicating Controller These controllers go to automatic if the handswitch is in manual LIC-3-173 SG 2 upon actuation of the following accident signals:
LIC-3-174 SG 1 LIC-3-175 SG 4 2/3 Lo-Lo Level any Steam Generator Safety Injection Blackout Loss 110th Main Feed Pumps A safety injection signal would cause loss of both main feed p,unps as would 10-10 steam generat;r IcVel and blackout. There-fore, reset of ESF signals would not change controller state since loss of both main feed pumps " seals in" the ESF signal.
Also these controllers have a "bumpless" transfer from auto to manual. This means the manual output tracks the auto output when the controller is in auto. Upon switching the controller to manual, the output is frozen at the point where the last auto output was.
If the handswitch is in auto, there is no change in operation when the ESF signals are reset.
e 2
TABLE A-1 (cont'd.)
LCV-3-148 SG 3 Level valve These interact in the following manner.
If the ils is in the manual LCV-3-156 SG 2 bypass position, the large valve closes and the small valve modulates.
LCV-3-164 SG 1 Upon rgccipt of an accident signal when the pressure is above 500 LCV-3-171 SG 4 lbs/in, the small valve closes and the large valve modulates. As in LCV-3-148A SG 3 Level Bypass Cont V1v the first set of LIC's, any accident signal results in loss of both LCV-3-156A SG 2 main feed pumps and is thus " scaled in."
LCV-3-164A.
- 1f the handswitch is in auto, there is no change in operation when the LIC-3-148*
SG 3 Controller ESF signals are reset.
LIC-3-156*
SG 2 LIC-3-164*
SG 1 LIC-3-171*
SG 4 FCO-30-122 Cask Loading Area Exhaust Damper These are initiated by a phase A containment isolation or a high FCO-30-123 radiation signal from the auxiliary building genenal exhaust vent (the normal auxiliary building ventilation discharge). 'the auxiliary building isolation signal will not reset upon resetting the containment isolation signal. The auxiliary building isolation can be reset only if the initiating signals no longer exist. This will cause the cask load area exhaust dampers to reopen provided there is not a high radiation reading in the spent fuel pit area.
FCO-31A-17 Spreading Room Supply Fan These dampers close and fans stop in the event of a control room FCO-31A-102 isolation. This isolation can be initiated by a safety injection FCO-31A-103 Toilet and Locker Room Exhaust Fan or by the presence of chlorine, smoke, or high radiation levels in the FCO-31A-104 fresh air supply duct and by manual initiation from the main control FCO-31A-105A room. The control room isolation signal seals in and will not reset B, D Main Cont. G Spread Rm Fresh Air Isol upon the reset of the SI signal. Opening of the fresh air supply and Damp exhaust paths will occur upon resetting the control room isolation FCO-31A-106A, signal. This signal can only be reset, however, if the initiating 8, D signal no longer exists.
FCO-5.1A-238 Smoke Removal Fan Circuit FCV-74-16 RilR lleat Exchanger A Outlet Flow Cont These are self-regulating valves which use an analog signal to (ilCV-606) control flow from the RilR heat exchangers. The flow valve is preset TCV-74-28 B
by adjustment of the flow contre lcr in the main control room. Upon (llCV-607) initiation of safety injection, the analog control signal is bypassed and the valve goes to the full open position. This will permit full RilR flow to the.RCS after RCS pressure has dropped below the shutoff heat of the RiiR pumps.
With RCS pressure above the pump shutoff heat, lillR flow is recirculated through the minimum flow bypass line; no flow is delivered to the reactor coolant system.
Followi safety injection signal, the valvas will return to tgi gset of gig ow cont L.
e 3
TABLE A-1 (cont'd.)
mode.
Presently, we feel that this control scheme ensures adequate equipment control and no modification is necessary.
llowever, we are reevaluating operational conditions where SI reset might occur during this mode of operation to determine if other control schemes would enhance equipment control.
FCV-1-51 Aux Feed Pump Turb Trip G Throttle V1v This valve does not return to original state upon reset of ESF Signal.
FCV-1-52 Aux Feed (Pump Turb Speed Cont In the flow control mode, this valve regulates the flow from the turbine driven auxiliary feedwater pump.
In the manual speed mode c it regulates the turbine speed and allows it to be ramped up or
-down.
If the control room handswitch is in the auto position, an SI signal has no effect on the valve.
If the handswitch is in the ACC reset or manual mode, an SI signal will force the valve to the auto (flow control) mode.
If the SI signal is then reset, the valve remains in the position it was in just prior to the reset.
The valve does not return to its original position.
PCV-65-81 Shield Bldg Vent Isol Viv, Train A Resetting the ESF signal to these valves will not cause the valves FCV-65-86 Cntmnt Annulus Isol V1v, Train A to change from the position initiated by the ESF signal.
PCV-65-83 Shield Bldg Vent Isol Viv, Train B PCV-65-87 CNTknt Annulus Isol J1v, Train B FCV-43-55 Steam Gen No. 1 Bd Isol Viv The sample lines come off the steam generator blowdown line at FCV-43-58 No. 2 a point between the two blowdown isolation valves. The blowdown FCV-43-61 No. 3 sample valves isolate on a phase A containment isolation signal FCV-43-64 No. 4 or if the auxiliary feedwater system starts, the blowdown valves isolate on a phase A containment' isolation.
Phase A containment isolation is caused by either manual initiation or by an SI signal.
Since an SI signal also starts the auxiliary feedwater system, resetting a containment isolation which was initiated by an SI will not cause the sample isolation valves to open. Therefore, the sample isolation valves will open on the reset of a containment isolation signal only if the signal was manually initiated. This line could then provide a flow path of liquid from inside containment only if the inboard blowdown isolation valve is manually opened.
R::ctor Upper Compartment Cooler Fan Rige, tor Lower Compartment Cooler Fan Upon initiation of containment phase B isolation, the cooling water Control Rod Drive Mechanism Cooler Fan supply to the coolers is isolated and the fans are tripped.
Following reset of the isolation signal, the fans are allowed to restart. Restart of the fans after isolation signal reset and the resulting circulation and mixing of containment air in the upper and lower compartment spaces will not degrade plant safety performance.
e TABLE A-J (cont'd.)
4 Shutdown Bd Room A Pressurizing Fan Phase A containment isolation trips the pressurizing fans and initiates auxiliary building isolation which starts the auxiliary building emergency gas treatment system. The ABEGTS maintains a slight negative pressure in the building to prevent leakage of unfiltered air to the outside. Reset of the contain-ment isolation signal will allow restart of the low capacity shutdown board room pressurizing fans; however, auxiliary building s
i isolation and ABEGTS operation is not changed by phase A isolation reset.
Fan restart will maintain the pressure in the board rooms slightly above the pressure in the surrounding area of the auxiliary building.
Penntration Room Cooler Fans Elevations 714, 669, 690 Space Coolers for Fans Upon reset of ESF signal, these coolers and fans are secured; Sptnt Fuel Pit Pumps Space Coolers however, thermostats in the affected areas will restart the units EGTS Room Coolers if the temperature in the space exceeds a preddtermined setpoint.
Turbine Driven AFW and Boric Acid Space Coolers Pipa Chase Cooler Fans Auxiliary Building General Supply and Exhaust Fan On reset of ESF signal, this fan will restart; however, isolation Elevation 714 valves downstream of the fans (which do not reset) prevent ofrflow.
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