DOE-HDBK-1019/2-93
Reactor Theory (Nuclear Parameters)
SAMARIUM AND OTHER FISSION PRODUCT POISONS
SAMARIUM AND OTHER FISSION PRODUCT POISONS
The fission product poison that has the most significant effect on reactor
operations other than xenon-135 is samarium-149.
Samarium-149 behaves
significantly different from xenon-135 due to its different nuclear properties.
EO 4.10
DESCRIBE how samarium-149 is produced and removed from
the reactor core during reactor operation.
EO 4.11
STATE
the
equation
for
equilibrium
samarium-149
concentration.
EO 4.12
DESCRIBE how equilibrium samarium-149 concentration
varies with reactor power level.
EO 4.13
DESCRIBE how samarium-149 concentration changes following
a reactor shutdown from steady-state conditions.
EO 4.14
DESCRIBE how samarium-149 concentration changes following
a reactor startup.
EO 4.15
STATE the conditions under which helium-3 will have a
significant effect on the reactivity of a reactor.
Production and Removal of Samarium-149
Samarium-149 is the second most important fission-product poison because of its high thermal
neutron absorption cross section of 4.1 x 104 barns. Samarium-149 is produced from the decay
of the neodymium-149 fission fragment as shown in the decay chain below.
149
60
Nd
b
1.72 hr
149
61
Pm
b
53.1 hr
149
62
Sm (stable)
Rev. 0
NP-03
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