ML17192A671

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Emergency Procedure DGA-1,REvision 4, Loss of Coolant (Break Inside Drywell).
ML17192A671
Person / Time
Site: Dresden Constellation icon.png
Issue date: 01/12/1980
From:
COMMONWEALTH EDISON CO.
To:
Shared Package
ML17192A611 List:
References
DGA-1, NUDOCS 8005080487
Download: ML17192A671 (8)
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  • . LOSS OF COOLANT (BREAK INSIDE DRYWELL) e , *, ~oosoao4S"1 DGA-1 Revision 4 January 12, 1980 A. SYMPTOMS
1. 902 (3)-3 Alarms
a. DRYWELL HIGH PRESSURE I*
b. _ .TORUS LEVEL HI/LO

,.,... ~. AUTO BLOWDOWN SYSTEM DW HIGH PRESS

d. REACTOR LOW WATER LEVEL I I
2. 902(3)-4 Alarms
a. DRYWELL EQUIP SUMP HI HI LEVEL b.. DRYWELL/TORUS AP HI/LO
c. DRYWELL EQUIP SUMP HI LEVEL
d. DRYWELL EQUIP SUMP HIGH TEMP
e. TORUS LEVEL HIGH
f. TORUS LEVEL LOW
g. TORUS WATER HIGH TEMP
h. DRYWELL FLOOR DRAIN SUMP HIGH LEVEL
i. DRYWELL FLOOR DRAIN SUMP HI HI LEVEL
j. VALVE LEAK DETECTOR SYS HIGH TEMP
3. 902 (3)-5 Alarms
a. CHANNEL A(B) MAIN STEAM LINE LOW PRESS
b. CHANNEL A(B) REACTOR LO LO LEVEL
c. CHANNEL A/B REACTOR LO LEVEL
d. PRIMARY CONTAINMENT HIGH PRESSURE
e. REACTOR VESSEL LO LEVEL
4. 902 (3)-8 Alarms 125V DC GROUND APPROVED 1 of 8
  • u*.u*.s.R.
  • DGA-1 Revision 4 B. AUTOMATIC ACTIONS
1. Reactor Scram
2. Group I, II and III Isolation
3. HPCI System Auto Initiation
4. MSIV Closure at Less Than 850 psig in RUN
5. SBGT System Initiates

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6. +2 psig drywell pressure and -59" reactor vessel level starts 120 second timer for Auto Blowdown System. Auto Blowdown System will initiate when timer times out provided a LPCI or Core Spray Pump is operating.
7. Auto start of Unit 2(3) and 2/3 Diesel Generators.
8. Recirculation Pumps runback if feedwater flow is lost.
9. Recirculation Pumps trip on Low Low reactor level.
10. LPCI Pumps start.
11. Core Spray Pumps start.
12. At < 350 psig, LPCI and Core Spray Injection Valves open.
13. RBCCW Pumps and Drywell Coolers trip.
14. +48" Rx level trips HPCI turbine.
15. +55" Rx level trips RFP's.
16. > 2/3 core coverage gives permissive for opening 1501-20A(B) and 1501-38A(B) to provide torus cooling.
17. > 1 psig DW pressure and > 2/3 core coverage gives permissive for opening 1501-27A(B), 1501-28A(B), 1501-18A(B) and 1501-19A(B) to provide DW and Torus Spray.
18. High reactor pressure causes Safety/Relief Valves to open.

APPRO\IEO JAN 12'80 o.o.s.R.

2 of 8

DGA-1 Revision 4 C. IMMEDIATE ACTIONS CAUTION Any AUTO ACTIONS which should initiate must be verified, preferably by at least two independent indications. Verific~

tion means that if the AUTO ACTION does not occur, t~e action should be accomplished manually. DO NOT manually initiate a system unless the AUTO function has failed.

DO NOT block or defeat a system logic unless adequate core cooling is assured.

1. VERIFY reactor scram. Follow the Reactor Scram procedure (DGP 2-3).
2. Maintain feedwater flow to the reactor if possible. Utilize multiple level indications.
3. VERIFY HPCI START.
4. VERIFY Emergency Diesel Generators 2(3) and 2/3 START. IF normal power is lost, VERIFY diesel generators CLOSE onto Buses 23-1 (33-1) and 24-1 (34-1).

NOTE IF normal power is not available, VERIFY sequential starting of LPCI and Core Spray Pumps after diesel generators have CLOSED onto buses.

5. VERIFY LPCI and Core Spray Pumps START.
6. VERIFY that recirculation loop selection for LPCI injection occurs.

CAUTION DO NOT manually OPEN Pressure Relief Valves until it. is verified that at least one Core Spray or one LPCI Pump is running.

NOTE If no ECCS is available, this requirement rriay be satisfied with a Condensate Puap provided the APPROVED pump is capable of adding water to the vessel. JAN 12 !80 3 of 8 0.0.S.R.

!~ *. - .

DGA-1 Revision 4

7. If*high pressure systems fail to initiate or cannot maintain level, VERIFY initiation of the Auto Blowdown System.
8. VERIFY that LPCI and Core Spray injection occurs when reactor pressure decreases to 350 psig as indicated by more than one indication.

D. SUBSEQUENT ACTIONS

1. Station an additional operator to monitor and control reactor vessel level. Multiple level indications should be utilized.

This operator shall be assigned no other function.

2. Refer to Procedure to Assure Adequate Core Cooling (DGA-19),

if any of the following conditions occur:

a. Reactor water level indications are continuing to decrease with ECCS operating.
b. Reactor water level is sustained at a level below the top of the active fuel as indicated by available level indications.
c. Reactor water level indication is unavailable.
d. Less than design flow is indicated on Feedwater or ECC Systems when design flow is required.
3. IF desired and IF level approaches the high trip setpoints for Feedwater and/or HPCI, take manual control of these systems to maintain level and to prevent trips of Feed-wa ter and HPCI Systems.
4. VERIFY that Group II Isolation occurred.
5. If level decreased to +8", VERIFY that Group III Isolation occurred.
6. IF a Group* I Isolation signal was received, VERIFY that Group I Isolation occurred.
7. EVACUATE the Reactor Building.
8. IF torus level reaches high level or Condensate Storage Tank reaches low level, VERIFY automatic transfer of HPCI suction.
9. VERIFY that SBGT Syst_em is operating.
10. IF the Main Condenser is still available, control pressure and cooldown using the Main Condenser.

CAUTION If opened manually for pressure control, Pressure Relief Valves should be rotated to distribute JAN l ) 'F11ri

- v.)

heat uniformly to the torus.

4 of 8 D.0.S.R.

DGA-1 Revision 4

11. IF the Main Condenser is unavailable:
a. IF only high pressure systems are required to maintain level and vessel pressure increases above normal operating, as indicated by more than one instrument, DEPRESSURIZE using the Isolation Condenser or one or more Pressure Relief Valves.
b. IF low pressure systems are required to maintain level and vessel pressure increases above the shutoff head of the low pressure systems as indicated by more than one indication, DEPRESSURIZE the vessel using the Isolation Condenser or one or more Pressure Relief Valves.
12. MONITOR containment pressure and temperature. CHECK multiple indications.
13. IF Relief Valves have been actuated, continually MONITOR and RECORD torus water temperature every 5 minutes. RECORD data on Figure 1 and file it in the operating surveillance files.
14. If the torus temperature reaches 120°F during isolation conditions, DEPRESSURIZE the reactor to below 150 psig at normal cooldown rates.

CAUTION VERIFY 2/3 core coverage before initiating containment cooling."

15. IF possible, SPRAY the torus airspace when the drywell pressure exceeds 2.0 psig.
16. IF the drywell pressure reaches and remains greater than 25 psig, INITIATE Drywell Spray.
17. Commence containment cooling as necessary to maintain torus water temperature less than 170°F.
18. Notify the Shift Supervisor of systems started manually.
19. Refer to "Post Accident Venting of Primary Containment" (DOP 1600-15).
20. START a Reactor Building Closed Cooling Water Pump.
21. When DW pressure has decreased below 2 psig, START Drywell Cooler Fans.

APPROVED JAN 12 '80 5 of 8 D.O.S.R.

DGA-1 Revision 4 CAUTION Determine the radiological condition of the drywell and reactor coolant before resetting an isolation.

22. PLACE all air operated valves associated with an isolation in the CLOSED position prior to resetting an isolation. Failure

. to do this may cause the valve to open automatically when the isolation is reset.

23. If the Relief Valves are actuated and torus temperature reaches 160°F or greater while the reactor pressure is above 150 psig, an external visual exam of the torus must be conducted before resuming power operation.

E. DISCUSSION This procedure assumes a loss of coolant a_t rates large enough to cause a reactor scram and/or initiation of the Primary Con-tainment Isolation System on high drywell pressure. Losses of coolant at lesser rates are covered by the Loss of Coolant (Slow Leak) procedure (DGA-2).

The goal of IMMEDIATE actions is to reduce the loss of primary inventory as quickly as possible. IMMEDIATE operator actions include verification of automatic actions and taking manual action to initiate an automatic function whenever multiple indi-cations exist that automatic actions did not occur when required.

On any automatic initiation of a safety function, the operator should assume a true initiating event has occurred until other-wise confirmed by two or more independent process indications.

Automatic controls should not be placed in Manual mode, unless

1) misoperation in Automatic mode is confirmed by at least two independent process parameter indications; or 2) core cooling is assured. If any system is switched from Automatic to Manual mode, then frequent checks of the controlled parameter must be made.

The indicated water level, where provided by YARWAY instrumentation utilizing reference legs in the drywell, is dependent upon drywell temperature. Very large increases in drywell temperature (an increase from 135°F to 340°F) could result in a level inaccuracy (as much as 14 inches) with indicated level being higher than actual level. During rapid r~actor depressurization (with Auto Blowdown for example), and particularly below 500 psig, the

'. operator should utilize GEMAC level indicators to give backup information on vess~l wa.ter level. The operator should not turn off any ECCS unless there is sufficient confirming infor-mation from GEMAC level instruments that vessel water level has been restored. The operator should not rely on the Yarways if erratic behavior, indicative of reference leg flashing, has occurred until the Yarway readings are on scale and in reasonable agreement with GEMAC instruments.

APPROVED 6 of 8 JAN 12'80

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DGA-1 Revision 4 The goal of the SUBSEQUENT actions is to bring the plant to a stable condition, where the vessel water level is steady or cycling.

within a satisfactory range, and containment cooling has been established. Other objectives include limiting the release of off-site radiation by maintai~ing the integrity of the primary and secondary containments and maintaining torus temperature below 170°F to prevent excessive loads to the pool boundary and structures during safety/relief valve discharges.

When manual operation of systems placed in manual is no longer needed, restore the system to Automatic/Standby mode, if possible.

Any Emergency Core Cooling System should not be shut off unless there are multiple confirming process indications that the core.

and containment are in a safe, stable condition.

APPROVED JAN 12 '80 7 of 8 D.0.S.R.

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APPROVED e . _

  • DGA-1 Revision 4 JAN 12'80 FIGURE l 0.0.S.R .. Torus Temperature and Time Temperature was taken Time Temp. Time Temp. Time Temp. '

Time . Temperature I I I  :

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