RQ-C-4871 (ELAP Events)

Question 1

During an ELAP event, why is it important to cool down the RCS in a timely manner?

Answer 1

• To maintain RCS inventory (i.e., protect RCP seals).

Question 2

During an FSG-3 event (Alternate Low Pressure Feedwater), what is the preferred source of water to feed the SGs and why?

Answer 2

• FLEX booster pump from either Lake Township OR FLEX lift pump. This pump can feed SGs that are at 290# (1st cooldown termination criteria). FP water cannot.

Question 3

What is the primary concern with depressurizing SGs less than 290# during an ELAP event?

Answer 3

• Return to criticality due to cooldown. Need time to borate.

Question 4

During an ELAP event, what is the concern regarding reflux boiling?

Answer 4

• If reflux boiling occurs, adequate cooling is maintained. However, this can lead to pockets of diluted water in the RCS cold legs that can become a problem if natural circulation is re-established.