Heat Sink CSF Procedures (RQ-C-4761)

Question 1

What is the primary reason to stop RCPs while in FR-H.1 (Loss of Heat Sink)

Answer 1

Extends the time to SG dry out due to removing the heat added by RCP operation

Question 2

What is a secondary reason to stop RCPs while in FR-H.1 (Loss of Heat SInk)

Answer 2

If RCPs are running it can reduce the effectiveness of bleed and feed

Question 3

For the purposes of the E-Plan, when does time zero occur during FR-H.1 (Loss of Heat Sink)

Answer 3

From the time you determine manual action from the Control Room will not be able to restore heat sink and heat sink is required

Question 4

If feed and bleed during FR-H.1 (Loss of Heat Sink) is delayed, what are the consequences

Answer 4

If feed and bleed is delayed then RCS pressure rises due to the heatup of the RCS to the point at which the SI pumps will no longer be able to inject. The longer it is delayed the less ECCS flow (feed) you’ll be able to establish.

Question 5

Why is feed and bleed not established in FR-H.1 (Loss of Heat Sink) if there are no CCPs available and SG WR levels are less than 31%

Answer 5

Without the additional inventory in the SGs feed and bleed will not be successful because RCS pressure is expected to rise above the shutoff head of the SI pumps. In this case the only success path is to establish AFW/CCPs

Question 6

During FR-H.1 (Loss of Heat Sink) what are the potential sources of feedwater in the preferred order

Answer 6

1) My AFW
2) Opposite Unit AFW
3) My MFW
4) My Condensate (will cause an SI due to one SG being depressurized)