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3.2 Irradiation channels

Neutron activation can be obtained from nuclear re-
action weather in nuclear reactor, neutron generator,
spallation sources or neutron sealed radioactive source.
Even though out there many type of neutron sources,
within the scope of this book, this chapter discusses
about NAA devices install at TRIGA type nuclear re-
search reactor. NAA technique utilizes neutron at the
reactor core. The irradiation is done in a specific hole
within the fuel elements in the reactor core. There are
three channel available withing the TRIGA reactor to
place the sample into the irradiation holes. First chan-
nel is the central timble, the hole is located in the cen-
ter of reactor core. The sample is place into the hole of
central timble via gravity only, while taking the sample
from central timble is done by apply some mechanism
an input into the shielding box. Proper safety precau-
tion and procedure in place to conduct this job. Typical
layout of central timble with respect to the reactor ap-
paratus is shown in Figure 3.3.

Central timble is used for irradiation when large ac-
tivity is required. This is because the thermal neu-
tron flux is the highest within the central timble. Typi-
cally, central timble is used for production of industrial
or medical radioisotope, The irradiation time also us-
ally longer as compared with the other irradiation pur-
poses.

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