Does radon remain inside solid radium?

[Philip Koeck]

When radium atoms inside solid radium turn into radon do they stay in their lattice positions at room temperature or do they diffuse/tunnel to the surface?

 

[Frabjous]

Is this really your question? I believe that uranium is the first element of the decay series (4.4 billion year half life) which produces radium (1620 year half life) so one would not expect to find large volumes in nature.

If you are interested in radon gas in nature, the term is emanation is used. The idea is that when radium decays, the radon picks up enough momentum to move tens of nm in grain material and the question is whether the radon is trapped within the original grain, trapped in another grain or released to void.

 

[Baluncore]

If the radon does not escape the grain immediately, then there will also be three alpha particles in the vicinity. One alpha was produced when radium decayed to radon, another alpha, a couple of days later when the radon decays to polonium, and then a third alpha a few minutes after that, as the polonium decays to lead.

 

[Philip Koeck]

Is this really your question? I believe that uranium is the first element of the decay series (4.4 billion year half life) which produces radium (1620 year half life) so one would not expect to find large volumes in nature.

If you are interested in radon gas in nature, the term is emanation is used. The idea is that when radium decays, the radon picks up enough momentum to move tens of nm in grain material and the question is whether the radon is trapped within the original grain, trapped in another grain or released to void.

I was thinking of a lump of radium produced in a lab.
So radon and other decay products can be trapped inside the radium, is that right?

 

[Philip Koeck]

If the radon does not escape the grain immediately, then there will also be three alpha particles in the vicinity. One alpha was produced when radium decayed to radon, another alpha, a couple of days later when the radon decays to polonium, and then a third alpha a few minutes after that, as the polonium decays to lead.

What happens to the alpha particles?
Do they just escape or do they get stuck between the radium atoms?
Would one eventually get bubbles of radon and helium inside the radium?

 

[Frabjous]

Due to radiation damage of metals in reactors, helium diffusion is a topic of study. A quick google sees discussion of helium bubbles in metals. You have reached the limits of my knowledge.

 

[DrClaude]

Moving the thread to Nuclear Engineering where it might catch the eye of some of our experts.

 

[rpp]

The quick answer is that some will escape and some will remain in the solid.

The longer answer is a lot more complicated. As others have pointed out, when radon is produced by the decay, it will impart energy on the lattice and will damage it. The radon gas (and helium) can migrate/diffuse and create small bubbles. If the radon diffuses to a surface or a crack boundary, it can escape. The shape of the radium (surface area) and cracks will all make a difference. Cracks include microscopic cracks, not just the cracks you can see. All of these processes depends on the temperature.

 

[Astronuc]

Most likely, the radon and He will form microbubbles in the lattice (radii on the order of nm), or sit in vacancies and interstitial sites in the metal crystal lattice. As rpp, the kinetics depend on temperature. Often bubbles/voids may form on grain boundaries, especially near 'triple point' intersections.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6480233/

We see microbubbles in stainless steels and Ni-alloys irradiated in thermal and fast reactors. The microbubbles are He from (n,α) reactions between fast neutrons and nuclei.

Near the surface, some He and Rn may escape. However, Ra sources are normally sealed to prevent escape of Ra and daughter (decay) products from migrating into the environment.

https://www.sciencedirect.com/topics/materials-science/helium-bubble

One can search on "Helium bubbles in irradiated stainless steels" and see what one finds.

 

[gleem]

I do not know all industrial applications but for medical uses in the treatment of cancer, radium was used by placing small metal capsules, needles, or plaques of a radium salt in or next to the tumors. These capsules had welds. Periodically they had to be tested to detect possible cracks by wiping the surface for the presence of radon decay products. The salts being powders allowed much of the radon to leave and build up in the capsules.