B13 - Nuclear Boiler

Question 1

What pumps inject inside the shroud?

Answer 1

HPCS, LPCS, RHR A,B,C

Question 2

What pumps inject outside the shroud?

Answer 2

RHR A,B (not safety), RCIC, Feedwater

Question 3

How many signals does it take to operate MSIV or SRV?

Answer 3

For both:

1 energized to open
2 de-energized to close

Question 4

What’s the core shroud?

Answer 4

2” thick, cylindrical, stainless steel structure that surrounds the core. Provides a barrier to separate upward flow from downward flow in the annulus.
Also serves as a floodable volume in the event of an accident that would tend to drain RPV

Question 5

What is the purpose of the TOP guide?

Answer 5

provide lateral support for the upper end of the fuel bundle, neutron monitoring, instruments, and neutron sources

Question 6

What is the control rod guide tube?

Answer 6

guides lower end of the control rod during movement cylinder around velocity limiter to help prevent free fall in the event of a control rod drop. Supports and provides coolant to flow into fuel support casing.

Question 7

What is the core support plate?

Answer 7

Provides lateral support for control rod guide tubes, 28 peripheral fuel bundles, and neutron source holders.

Acts as a partition, forcing coolant into the control rod drive tubes and to proceed upwards through fuel assemblies.

Question 8

What ensures proper orientation of control rod guide tubes and fuel support casing

Answer 8

Pins protruding from upper surface of core support plate

Question 9

How fast should MSIVs close?

Why?

Answer 9

3-5 seconds because,

> 3 seconds to prevent large pressure transients
< 5 seconds to minimize dose (protect the public) and to keep inventory in the core

Question 10

Why do we have water rods in the fuel?

Answer 10

increased moderation in the fuel

Question 11

what is the purpose of the spring in the fuel?

Answer 11

Allow for expansion and keeps fuel in place

Question 12

What is cladding made of?

Answer 12

Zircaloy 2

Question 13

What is the channel made of?

Answer 13

Zircaloy 4 (lower neutron absorption)

Question 14

What’s the fuel support piece “elephant’s foot”?

Answer 14

Fuel sits on it

Forces flow through the center bundles by placing orifices in peripheral bundles

Question 15

What is natural uranium used for?

Answer 15

reflect fast neutrons back into the core,

located in the top and bottom of fuel rods

Question 16

What is gadolinium used for?

Answer 16

burnable poison to allow larger amount of fuel without adding control rods.

Allows for better flux shaping

Question 17

What is the purpose of the jet pump?

Answer 17

uses recirc flow to force circulation into the rpv.

provides 2/3 flow

Also provides for 2/3 core coverage

Question 18

what is the steam separator?

Answer 18

increases steam quality from 10-13% to 90%

Question 19

How much core flow goes through the fuel bundles?

How much bypasses?

Answer 19

90% goes through the fuel bundles

10% is bypassed

Question 20

What is the quality of steam coming out of the fuel?

Answer 20

12%

Question 21

How many safety relief valves (SRV) are on the MSL?

Answer 21

20 SRVs

Question 22

What is the purpose of the steam dryers?

Answer 22

Increase steam quality from 90% to 99.9%

Question 23

What is the safety pressure limit of the Rx vessel?

Answer 23

1325 psig