REACTOR VESSEL INTERNALS

Question 1

What is the primary function of the thermal shield in reactor vessel internals?

Answer 1

Limits gamma heating of the vessel and helps shield it from neutron irradiation (neutron embrittlement).

Question 2

What is the purpose of internal vent valves in reactor vessel internals?

Answer 2

Operates during cold leg break to allow core recovery by venting steam out to prevent bubble formation.

Question 3

What do guide lugs in reactor vessel internals prevent?

Answer 3

Prevents rotation of core internals and prevents shifting.

Question 4

What percentage of core bypass flow bypasses the fuel, and through what paths?

Answer 4

Approximately 6.26% bypasses fuel via inlet/outlet interfaces, core barrel/baffle plates, guide tubes, and CRA instrument tubes.

Question 5

What is NDTT, and how is DTT calculated?

Answer 5

NDTT is the Nil-Ductility Transition Temperature, raised by fast neutron embrittlement. DTT = NDTT + 60°F.

Question 6

At what temperature does the Zirc-Water reaction occur, and what does it produce?

Answer 6

At 2200°F, the Zirc-Water reaction produces hydrogen gas.

Question 7

What is the purpose of CSS and outlet nozzle gap in reactor vessel internals?

Answer 7

They contribute to bypass flow.

Question 8

What is the purpose of Tech Spec 2.1.1 for Core Outlet Pressure vs. Temperature?

Answer 8

To maintain the integrity of the fuel cladding.