Chapter 3, Problem 3.42P

Interpretation Introduction

(a)

Interpretation:

The fraction of ${}^{137}\text{Cs}$ that have to decay for the level of cesium-related radioactivity of the contents, total mass of cesium (kg) represented by loss and year at which the level will be reached should be calculated.

Concept introduction:

The radioactive decay can be calculated as follows:

$N=N_0{\left(\frac{1}{2}\right)}^{t/t_{1/2}}$

Here, N is amount of subtance remain after time t, $N_o$ is initial amount of substance, t is time and $t_{1/2}$ is half life time.

The specific radioactivity per liter $S_{rL}$ can be calculated as follows:

$S_{rL}=S_r\rho$

Here, $S_r$ is specfic radioacivity and $\rho$ is concemtration.

Interpretation Introduction

(b)

Interpretation:

The concentration of ${}^{137}\text{Cs}$ in the tank (g/L) should be calculated when the waste was first stored.

Concept introduction:

The radioactive decay can be calculated as follows:

$N=N_0{\left(\frac{1}{2}\right)}^{t/t_{1/2}}$

Here, N is amount of subtance remain after time t, $N_o$ is initial amount of substance, t is time and $t_{1/2}$ is half life time.

The specific radioactivity per liter $S_{rL}$ can be calculated as follows:

$S_{rL}=S_r\rho$

Here, $S_r$ is specfic radioacivity and $\rho$ is concemtration.

Interpretation Introduction

(c)

Interpretation:

The reason for the radioactive cesium in the tank to poses a signifiicant environmental threat but not by the radioactive barium should be explained.

Concept introduction:

All the radioactive substance are harmfull for environment. The extent of harm they can cause to environment depends on their decay rate that depends on their half life time. More the decay rate or lower the half life time, less the substance is harmful to environment. Therefore, a substance with higher half life time will have low decay rate and it will be more harmful to the environment.