Question

Some radioactive nuclides have very short half-lives, for example, I-31 has a half-life of approximately 8 days. Pu-234, by comparison has a half-life of 24,000 years. Explain why both of these examples are dangerous, even though their half-lives are very different. Be sure to describe the different major types of radiation, and their hazards. (Radioactive Decay and Half-Life)

Answer 1

Here's what I find.

Step-by-step explanation:

Iodine-131

Iodine-131 is both a beta emitter and a gamma emitter.

`_(53)^(131)\text{I}\longrightarrow \, _(54)^(131)\text{Xe} +\, _(-1)^(0)\text{e} +\, _(0)^(0)\gamma`

About 90 % of the energy is β-radiation and 10 % is γ-radiation. Both forms are highly energetic.

The main danger is from ingestion. The iodine concentrates in thyroid gland, where the β-radiation destroys cells up to 2 mm from the tissues that absorbed it.

Both the β- and γ-radiation cause cell mutations that can later become cancerous. Small doses, such as those absorbed from the nuclear disasters in the Ukraine and Japan, can cause cancers years after the original iodine has disappeared.

Plutonium-239

Plutonium-239 is an alpha emitter.

`_(94)^(239)\text{U} \longrightarrow \, _(92)^(235)\text{Xe} + \, _(2)^(4)\text{He}`

Alpha particles cannot penetrate the skin, so external exposure isn't much of a health risk.

However, they are extremely dangerous when they are inhaled and get inside cells. They travel first to the blood or lymph system and later to the bone marrow and liver, where they cause up to 1000 times more chromosomal damage than beta or gamma rays.

It takes about 20 years for plutonium to be eliminated from the liver around 50 years for from the skeleton, so it has a long time to cause damage.