CNMT Spray Flashcards
Purpose/ function of cnmt spray? Safety design features?
- 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
Describe CNMT Spray, including flowpath
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)
Is spray header kept dry or wet? Why…and how?
Dry, because seismic analysis is calculated for it being dry. A drain valve in each header is left open up stream of nozzles
Auto actuation of CS What happens….
Manual + SI P-signal + SI (Pcnmt > 22 psig)(2/4) Man or P-signal = spray outlet valves open + SI = pumps start, discharge valves open
Spray additive tank design
Closed horizontal stainless steel tank, pressurized > 3.5 psig w/nitrogen, sized to achieve pH in recirc sump 8.0-9.5
Describe CS…….8992
Norm open w/ power removed, receives open signal on P-sig or manual actuation
Purpose CS-8994A/B
Spray additive outlet valves Open on manual actuation or P-signal (Pcnmt > 22psig) Allows NaOH to be allowed in CS pump eductor stream
Purpose CS-9001A/B
CS pump disch. valves Open on man. + SI…..or……P-signal + SI
When RWST reaches ~4%, and CNMT spray is still desired, how is this achieved?
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
9003A/B……..what is it? Interlocks……? Why………?
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)
Precautions and limitations for CNMT Spray
- 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