10.7 Medical Applications and Biological Effects of Nuclear Radiation

Radiation propagates in all directions from its source, much as electromagnetic radiation from a light bulb. Is activity concept more analogous to power, intensity, or brightness?

Isotopes that emit $\alpha$ radiation are relatively safe outside the body and exceptionally hazardous inside. Explain why.

Find the radiation dose in Gy for: (a) A 10-mSv fluoroscopic X-ray series. (b) 50 mSv of skin exposure by an $\alpha$ emitter. (c) 160 mSv of $\beta^{-}$ and $\gamma$ rays from the $^{40} \text{K}$ in your body.

In the 1980s, the term picowave was used to describe food irradiation in order to overcome public resistance by playing on the well-known safety of microwave radiation. Find the energy in MeV of a photon having a wavelength of a picometer.

One half the $\gamma$ rays from $^{99 \text{m}} \text{T} \text{c}$ are absorbed by a 0.170-mm-thick lead shielding. Half of the $\gamma$ rays that pass through the first layer of lead are absorbed in a second layer of equal thickness. What thickness of lead will absorb all but one in 1000 of these $\gamma$ rays?

A plumber at a nuclear power plant receives a whole-body dose of 30 mSv in 15 minutes while repairing a crucial valve. Find the radiation-induced yearly risk of death from cancer and the chance of genetic defect from this maximum allowable exposure.

The wiki-phony site states that the atomic mass of chlorine is 40 g/mol. Check this result. Hint: The two, most common stable isotopes of chlorine are: $_{17}^{35} \text{Cl}$ and $_{17}^{37} \text{Cl}$. (The abundance of Cl-35 is $75.8 \%$, and the abundance of Cl-37 is $24.2 \%$.)

A nuclear physicist finds $1.0 \mu g$ of $^{236} \text{U}$ in a piece of uranium ore (T_1/2 = $2.348 \times 10^{7} \text{y}$). (a) Use the decay law to determine how much $^{236} \text{U}$ would had to have been on Earth when it formed $4.543 \times 10^{9} \text{y}$ ago for $1.0 \mu g$ to be left today. (b) What is unreasonable about this result? (c) How is this unreasonable result resolved?

According to your lab partner, a 2.00-cm-thick sodium-iodide crystal absorbs all but $10 \%$ of rays from a radioactive source and a 4.00-cm piece of the same material absorbs all but $5 \% ?$ Is this result reasonable?

The ceramic glaze on a red-orange “Fiestaware” plate is $\text{U}_{2} \text{O}_{3}$ and contains 50.0 grams of $^{238} \text{U}$, but very little $^{235} \text{U}$. (a) What is the activity of the plate? (b) Calculate the total energy that will be released by the $^{238} \text{U}$ decay. (c) If energy is worth 12.0 cents per $\text{kW} \cdot \text{h}$, what is the monetary value of the energy emitted? (These brightly-colored ceramic plates went out of production some 30 years ago, but are still…

A piece of wood from an ancient Egyptian tomb is tested for its carbon-14 activity. It is found to have an activity per gram of carbon of $A = 10 \text{decay}/\text{min} \cdot \text{g}$. What is the age of the wood?

The Galileo space probe was launched on its long journey past Venus and Earth in 1989, with an ultimate goal of Jupiter. Its power source is 11.0 kg of $^{238} \text{Pu} ,$ a by-product of nuclear weapons plutonium production. Electrical energy is generated thermoelectrically from the heat produced when the 5.59-MeV $\alpha$ particles emitted in each decay crash to a halt inside the plutonium and its shielding. The half-li…

Engineers are frequently called on to inspect and, if necessary, repair equipment in nuclear power plants. Suppose that the city lights go out. After inspecting the nuclear reactor, you find a leaky pipe that leads from the steam generator to turbine chamber. (a) How do the pressure readings for the turbine chamber and steam condenser compare? (b) Why is the nuclear reactor not generating electric…

For the reaction, $n + ^{3} \text{He} \rightarrow ^{4} \text{He} + \gamma$, find the amount of energy transfers to $^{4} \text{H} \text{e}$ and $\gamma$ (on the right side of the equation). Assume the reactants are initially at rest. (Hint: Use conservation of momentum principle.)