Loss of NNI / Loss ICW

Question 1

How do the power supplies for NNI operate?

Answer 1

Question 2

What major actions are taken for a loss of NNI X AC and DC?

Answer 2

Trip Rx, Close RCS Makeup Block (PZR controller fails 50%) and maintain PZR lvl using HPI block 90 - 100”, CV-1206 in override, Manually operate PZR heaters

Question 3

What major actions are taken for a loss of NNI X DC only?

Answer 3

Ensure FW demands, RX demand and diamond in manual, CV-1206 in override, Isolate RCS makeup and use HPI block to control PZR lvl 200 - 220”, bypass CV-1207 and operate heaters in manual.

Question 4

What major actions are taken for a loss of NNI X AC only?

Answer 4

Trip RX, Operate HPI block to control pzr lvl, Close CV-1206 and operate PZR heaters in manual.

Question 5

What major actions are taken for a loss of NNI Y?

Answer 5

If MFW on D/P control then take MFPs to hand.

Question 6

What are the effects for loss of NNI power supplies?

Answer 6

Loss NNI X AC & DC (Same for DC only): CV-1207 and CV-1235 fail to 50% / PZR htr auto controls fail

NNI X AC Only: CV-1207 fails closed / CV-1235 fails indetereminate / PZR htrs fail off

NNI Y: MFP DP fails low / LD flow indication unavailable

Question 7

What major actions are taken if all but one ICW pump running?

Answer 7

Place failed pump in PTL, Open all crossconnects, isolate letdown and one letdown cooler, isolate icw to SFP coolers and maintain < 2500 gpm. Secure additional loads that aren’t needed, restore LD.