Precourse ILT RCPs

Question 1

What are the two purposes of the RCPs?

Answer 1

1. Circulate flow through the core to prevent DNB
2. Heat up the RCS from cold shutdown to NOT

Question 2

What is the purpose of the first RCP seal?

Answer 2

-Forms the main pump seal
-Seal type: film riding face seal; not impacted by pump rotation

Question 3

What are the interlocks required to start an RCP?

Answer 3

Both LSIVs open (for CL bypass can be open)
CC to oil coolers
At least 1 RCFC running
>275 psid across #1 seal
Loose parts monitoring system operating
RCP bearing temps trending on computer
Seal injection water established

Question 4

What are the flow rates through each RCP seal?

Answer 4

1 seal 3 gpm

#2 seal 3 gph
#3 seal 400 cc/hr

Question 5

Where does the #1 RCP seal leakoff discharge to?

Answer 5

The VCT

Question 6

Where does the #2 RCP seal discharge leak off to?

Answer 6

to the RCDT

Question 7

Where does the #3 RCP seal leak off go to?

Answer 7

To the Containment floor drain sump

Question 8

What is the purpose of the RCP thermal barrier?

Answer 8

Limits heat transfer from RCS to pump internals
Labyrinth seals restrict upward RCS flow during loss of seal injction

Question 9

What is the purpose of the thermal barrier heat exchanger?

Answer 9

On a loss of seal injection, it cools the RCS going up to the seals
It is cooled by CC

Question 10

What is the purpose of the Flywheel?

Answer 10

Flywheel provides pump coast down time to ensure DNBR is not exceeded on a RX trip with loss of power
Extends coastdown flow for 10 seconds as pump trips

Question 11

What is the purpose of the anti rotation device?

Answer 11

Prevents reverse rotation which could cause high starting currents, disengages at ~70 rpm

Question 12

What conditions require a manual trip of an RCP?

Answer 12

No shaft rotation within 2 seconds
<200 psid across #1 seal
#1 seal leak off flow <0.2 gpm
Motor bearing temperature >195F without CC
Lower bearing temp >225F
#1 seal leak off temp >235F
>700 amps for >35sec
Vibs >0.31 in./sec
Loss of all seal cooling

Question 13

What is the source of water for the #1 RCP seal?

Answer 13

CV

Question 14

What is the source of water for the #2 RCP seal?

Answer 14

CV

Question 15

What is the source of water for the #3 RCP seal?

Answer 15

PW standpipe

Question 16

What happens on a loss of seal injection?

Answer 16

CC cools hot RCS via thermal barrier
pump may continue to operate IF: seal outlet <235F AND lower radial bearing <225F
Seal assumed to last 1 minute with no CC and no seal water injection
IF seal outlet temp >235F OR lower radial bearing >225F limit RCS cooldown to <50 F/min

Question 17

What are the effects of changes in leak off path back pressure?

Answer 17

backpressure for #1 seal is 15-20 psig from the VCT. If backpressure rises, it will cause a rise in leakage through the #2 seal