ML17192A674
| ML17192A674 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 01/26/1980 |
| From: | COMMONWEALTH EDISON CO. |
| To: | |
| Shared Package | |
| ML17192A611 | List: |
| References | |
| DGA-4, NUDOCS 8005080497 | |
| Download: ML17192A674 (4) | |
Text
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- f 9 soososo4-11 DGA-4 Revision 2 January 26, 1980 HIGH REACTOR WATER LEVEL A.
SYMPTOMS
- 1.
Alarms.
- a.
Rx Vessel High Level, Panel 902(3)-5.
- b.
Turb. EHC Remote Manual Device, Panel 902(3)-7.
- c.
RFP Auto Trip, Panel 902(3)-6.
- 2.
Feedwater flow greate.r than steam flow with reactor vessel level above normal.
- 3.
Flow On Light on Panel 902(3)-S.
- 4.
Condensate deminerallzer high dp.
B..
A(TTOM.ATIC ACTIONS
- 1.
Reactor feed pump trip at +55 inches.
- 2.
Turbine trip at +SS inches and auxiliary power transfers.
- 3.
Reactor scram if turbine first stage pressure greater than 45%.
- 4.
If the HPCI Turbine is operating, it will trip at +48 inches.
C.
IMMEDIATE OPERATOR ACTIONS NOTE LOCAL MANUAL control of Feedwater Regulating Valves. may be attempted at any time.
Th~. pace of the tran-sient will be th~ determining factor.
- 1.
IF Feedwater Regulating Valve has
- a.
Failed in AlTTO - :(1)
Take ~NlTAL control and establish normal water level using more than one level indication.
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(2)
IF valve does not respond in MANUAL and level is con-tinuing to increase attempt to throttle flow with FRV Isolation Valve.
CAlTTION IF reactor scrams or. feedwater controls must be abandoned, ensure the Level Set-point is returned to normal.
NOTE In lieu of the following step, it is possible to adjust recirculation flow until water level settles out at a constant level within the operating range.
However, consideration must be given to operating power level, fuel limits, etc. before performing such a maneuver *. This consideration is especially important for high or increasing level.
- b.
Locked Out -
(1)
RAISE Level Setpoint to match level.
(2). Attempt to RESET.
(3)
IF valve resets, restore Level Setpoint and level to normal.
(4)
IF valve does not reset, restore Level Setpoint to normal and
.attempt to throttle flow with FRV Isolation Valve.
,.* r.*:,
- c.
Failed OPEN -
(1) 'PLACE the other Feedwater Regulating Valve in service.
(2) Take MANlTAL control of the operable
- Feedwater Regulating Valve and atteapt to restore level.
(3) Isolate the failed Feedwater Regulating
- Valve.
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i:Zevision Z
- 2., e e **~*
- IF RFP's are in RtTNODT and reactor water level is above normal and increasing, CHECK that the Feedwater Control System RESETS to *the,. Level Control mode.
CAUTION IF ~ter level increases above the range of the narrow range level instruments, MANUALLY SCRAM the reactor.
Drain the HPCI steam supply and Main Steam supply lines before starting up.
- 3.
VERIFY RFP's and Main Turbine TRIPS when level reaches +55".
- 4.
DE-SELECT Standby RFP and VERIFY Standby RFP is TRIPPED.
- 5.
IF reactor is scrammed by Turbine Trip or MANUALLY, follow the Scram procedure (DGP 2-3).
D.
SVBSEQllENT OPERATOR 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.
IF level control was regained by throttling the FRV Isolation Valve, attempt to TRANSFER control to the other Feedwater Regulating Valve.
- 3.
IF neither Feedwater Regulating Valve responds in AllTO, take LOCAL MANUAL control of the valve in service.
E.
DISCUSSION High water level in the reactor vessel during power operation can result in major damage to the Main Turbine, the HPCI Turbine, Main Steam line piping and reactor vessel.
High water level can result from the following conditions:
-1.
Norm.al startup and shutdown operation.
- 2.
Feedwater regulator valve failures.
- 3.
Reactor feedwater pump' "RtTNOlTT".
- 4.
. Vessel depressurization during relief valve operation or under break condi ti.ans.
3 of 4 APPP'JVtD JAN 26 !80 0.0.S.f?..
IJGA-l:i Revis ion 2,*.
This procedure dea,ls with. feedwater regulating valve failures or reactor feedwater pump "RUNOllT" *. High water level may be a normal expectation during:'. startup or when shutdown.
Any high levels that occur as a result of vessel depressurization is covered by other procedutes.
- IF a high RFP Trip occurs*, as soon as the water level has lowered, the Standby RFP ~ill.AlTTO start unless the Control Switch. _is placed in the TRIPPED position and allowed to return to the NORMAL AFTER TRIP position.
A RFP may then be started in a normal manner when desired.
Following many transients, such as a RFP Trip and virtually any.reactor scram from power, reactor water level will de-crease rapidly and normally cause the level* control system to go.to a RllNOlTT or Flow~Control mode.
The Operator must maintain water level within the limits of his narrow range indication.
On a reactor scram, an automatic setdown of reactor water
- level setpoint to one-hal~ of its original value (approximately 15 inches) takes place.
An alarm, F.W. LEVEL SETPOINT AUTO -
RUNBACK, will actuate on Panel 902(3)-5.
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