CONTROL RODS
DOE-HDBK-1019/2-93
Reactor Theory (Nuclear Parameters)
CONTROL RODS
Most reactors contain control rods made of neutron absorbing materials that are
used to adjust the reactivity of the core. Control rods can be designed and used
for coarse control, fine control, or fast shutdowns.
EO 5.1
DESCRIBE the difference between a "grey" neutron absorbing
material and a "black" neutron absorbing material.
EO 5.2
EXPLAIN why a "grey" neutron absorbing material may be
preferable to a "black" neutron absorbing material for use in
control rods.
EO 5.3
EXPLAIN why resonance absorbers are sometimes preferred
over thermal absorbers as a control rod material.
EO 5.4
DEFINE the following terms:
a.
Integral control rod worth
b.
Differential control rod worth
EO 5.5
DESCRIBE the shape of a typical differential control rod
worth curve and explain the reason for the shape.
EO 5.6
DESCRIBE the shape of a typical integral control rod worth
curve and explain the reason for the shape.
EO 5.7
Given an integral or differential control rod worth curve,
CALCULATE the reactivity change due to a control rod
movement between two positions.
EO 5.8
Given differential control rod worth data, PLOT differential
and integral control rod worth curves.
Selection of Control Rod Materials
Rods of neutron-absorbing material are installed in most reactors to provide precise, adjustable
control of reactivity. These rods are able to be moved into or out of the reactor core and
typically contain elements such as silver, indium, cadmium, boron, or hafnium.
NP-03
Rev. 0
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