An 87-kg worker at a breeder reactor plant accidentally ingests 2.5 mg of dust. has a half-life of 24,100 y, decaying by alpha decay. The energy of the emitted particles is 5.2 MeV, with a quality factor of 13. We may assume that the plutonium resides in the worker’s body for 12 h, and that 95% of the emitted particles are stopped within the body. We have to calculate (a) the number of plutonium atoms ingested; (b) the number that decay during the 12 h; (c) the energy absorbed by the body; (d) the resulting physical dose in rad; and (e) the equivalent biological dose in rem.

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(a)

The number of atoms in 2.5 mg of dust will be

(b)

The half-life of is 24,100 y. Therefore, its disintegration constant will be

The decay rate of -nuclides will be

Therefore, of the -nuclides that would have decayed in 12 h will be

(c)

The energy of the emitted particles is 5.2 MeV, with a quality factor of 13 and that 95% of the emitted particles are stopped within the body. Therefore, the energy absorbed by the body will be

(d)

The strength of radiation is defined as 1 rad if of energy is absorbed by the body. Therefore, the resultant physical dose will be

(e)

As the quality factor of alpha particle radiation is 13, the equivalent biological dose will be