CNMT Spray

Question 1

Purpose/ function of cnmt spray? Safety design features?

Answer 1

• remove heat from ATM following LOCA - remove fission products from cnmt ATM after LOCA - deliver NaOH to ensure proper sump pH - work w/CFCU’s (1 train CS, 2 CFCU) to maintain < 47 psig following DBA - basic pH helps scrub f.p., retain in solution, minimize corrosion of carbon steel

Question 2

Describe CNMT Spray, including flowpath

Answer 2

One spray additive tank, one tank isolation (8992), two trains of spray additive isolation valves (8994A/B), two pumps, two discharge valves (9001A/B), two RHR cross connect valves (9003A/B) down stream of discharge valves, two spray ring headers Once activated, pumps start and flow through eductor that entrains NaOH into pump flow path (~35gpm NaOH/train) , Pump suction is from RWST. Pump discharges (~2466gpm/train) to spray ring header and sprays CNMT (~15 gpm/nozzle)

Question 3

Is spray header kept dry or wet? Why…and how?

Answer 3

Dry, because seismic analysis is calculated for it being dry. A drain valve in each header is left open up stream of nozzles

Question 4

Auto actuation of CS What happens….

Answer 4

Manual + SI P-signal + SI (Pcnmt > 22 psig)(2/4) Man or P-signal = spray outlet valves open + SI = pumps start, discharge valves open

Question 5

Spray additive tank design

Answer 5

Closed horizontal stainless steel tank, pressurized > 3.5 psig w/nitrogen, sized to achieve pH in recirc sump 8.0-9.5

Question 6

Describe CS…….8992

Answer 6

Norm open w/ power removed, receives open signal on P-sig or manual actuation

Question 7

Purpose CS-8994A/B

Answer 7

Spray additive outlet valves Open on manual actuation or P-signal (Pcnmt > 22psig) Allows NaOH to be allowed in CS pump eductor stream

Question 8

Purpose CS-9001A/B

Answer 8

CS pump disch. valves Open on man. + SI…..or……P-signal + SI

Question 9

When RWST reaches ~4%, and CNMT spray is still desired, how is this achieved?

Answer 9

The CS -> RHR x-connects are opened (CS-9003A/B) and RHR is split and cnmt recirc sump is source, RHR pumps are driving force, connected just upstream of spray header nozzles

Question 10

9003A/B……..what is it? Interlocks……? Why………?

Answer 10

X-connect RHR provide flow through spray nzl -Associated 8982A/B open (cnmt sump recirc valve)(don’t drain RWST to floor) -8701 or 8702 closed (don’t spray cnmt in norm cooling mode)

Question 11

Precautions and limitations for CNMT Spray

Answer 11

• don’t open 9001A/B while lined up to RWST (drain RWST to CNMT floor) - don’t fill CS system downstream of 9001A/B - wear proper PPE when handling NaOH