LOAF Flashcards
How do RCS parameters respond to a Loss of All Feedwater?
Assume SBCS is available.
SGWL will lower.
SBCS will continue to maintain RCS Tc as long as the SGs have inventory.
Therefore RCS pressure and Level will remain constant.
Once dry out occurs, Tc will begin to rise.
SG pressure will begin to lower.
Letdown will respond to maintain Level and therefore pressure.
Eventually letdown cannot limit PZR level rise due to Tc rise.
Pressurizer pressure will rise as the PZR becomes solid.
PZR safeties will begin to lift.
RCS temperature will continue to rise.
Core uncovery will occur in about 1 hour after dry out.
Why are RCPs secured?
The intent of this step is to minimize heat input to the RCS.
A LOAF results in a reduction of the ability of the steam generators to remove heat from the RCS.
Heat input to the RCS is minimized by stopping all four RCPs.
Natural circulation heat removal is adequate to remove decay heat generated in the core.
What are all the available ways to restore Feed in 40EP-9ZZ06, Loss of All Feed?
SA-38 Resetting AFA-P01 SA-39 Local Operation of AFB-P01 SA-40 Local Operation of AFA-P01 SA-41 Local Operation of AFN-P01 SA-112 Manual Operation of AFA-P01 during a security event SA-43 Restarting MPs SA-44 Condensate Pumps SA-118 X-tie FP to AFW
Describe SA-40, Local Operation of AFA-P01.
Include steps in Attachment 40-A and where communications occur between the CR and the AO in the field.
a. CR directs the AO to perform attachment 40-A.
b. AO will close AFA-HV-54, open breakers to de energize governor control power, align instrumentation, and verify AFA-HV-54 is reset. He will inform the CR that AFA-P01 is ready for local operation.
c. CR will direct AO to open steam supplies to AFA-P01 (this is up on the 120’)
e. CR will determine which generator will be fed.
f. CR will direct the appropriate feed valves be opened. (Some valves are powered by PKC and therefore may be operator from control room, may even already be open due to AFAS)
g. CR will direct AO to manually open AFA-P01 until adequate feed flow is obtained.
Loss of vacuum has occurred. PBB-S04 is down powered due to a failure of NBN-X04 and the B EDG has failed. Condensate pumps are running. MFPs, AFA-P01, AFN-P01 are all unavailable. Should the crew enter LOAF and depressurize the SGs to feed the condensate pumps, or, should the crew enter the Functional Recovery procedure, power PBB-S04 from NBN-X03, and feed with AFB-P01?
Why?
The crew should GO TO the Functional Recovery Procedure and power PBB-S04.
Per the EOP Operations Expectations: The CRS should consider vital bus recovery strategies available in the FRP to restore a high pressure source of feed before using condensate pumps or FP water, if those strategies will likely rapidly restore the bus and feed water.
What is the limit and basis for the limit when establishing feed flow to a dried out SG?
1000gpm or 1x10E6 lbm/hr.
Based upon feed ring water hammer testing, steam generator design considerations, and decay heat removal ability, an appropriate guideline to an operator for re-establishing feed flow to a hot dry steam generator should be to supply as much feed flow as possible from the system being used to restore feed water and not exceed the high feed flow limit.
This guideline is intended to apply to the situation where the plant is clearly in extremis, i.e., dry out has occurred and the plant is not able to be placed on shutdown cooling.
The limit is high enough so as to not unduly hinder an operator while at the same time remains within known analyzed conditions.
Describe how SA-44, Feeding with Condensate Pumps, is performed. Write out your brief for the cool down and describe when this takes place.
a. Determine which SG will be fed (only 1!)
b. Direct an operator to perform steps 1-10 to align the feed path and start a condensate pump
c. Brief “ We will be commencing a rapid controlled depressurization of the No.1 SG to 400-450psig in order to feed using a condensate pump. We will be starting the ‘A’ HPSI pump and open 1 injection valve, start all Charging pump, and monitor for letdown to respond. OATC will be resetting MSIS and SIAS set points. BOP will track the cool down using SA-5. No.2 SG will be maintained 1140-1200 psia using ADVs. BOP will monitor SG pressures and Tc. End of brief”
d. Direct BOP to perform step 14 or 15 to depressurize the selected SG and feed with a condensate pump.
What is the limit for cool down rate when depressurizing the SG to feed with condensate pumps?
Why?
The SG is depressurized by a rapid controlled cool down.
The limit of 100F/Hr may be exceeded.
Rapid controlled cool down is defined as being able to stop the cool down as well as being able to reset MSIS and SIAS set points.
Reestablishing feed water to recover heat removal capabilities has priority over the consequences of over cooling.
