$${ } ^ { 137 } \mathrm { Cs }$$

question 15

Essay

$${ } ^ { 137 } \mathrm { Cs }$$ is a common and particularly troublesome fission fragment produced in thermal neutron reactors. The difficulty with ${ } ^ { 137 } \mathrm { Cs }$ arises because of its long half-life $( 30$ years) in the $\beta$ decay chain (Figure $6.6$ ). Calculate the time required for ${ } ^ { 137 } \mathrm { Cs }$ in nuclear reactor waste to decay to $10 ^ { - 6 }$ of its original activity.

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Definitions:

Medulla

A section of the brainstem that controls vital bodily functions such as heartbeat and breathing.

Hair Root

The part of the hair located below the surface of the epidermis.

Hair Shaft

The visible part of the hair that extends above the skin surface, made of keratin and dead skin cells.

Hair Follicle

Invagination of the epidermis into the dermis; contains the root of the hair and receives the ducts of sebaceous and apocrine glands.