Technical accuracy of the Chernobyl miniseries.

[wraper]

I only hope that these tanks can withstand the next big earthquake.

Well, they are not that bad actually. That water is processed to remove contamination but tritium (hydrogen-3 isotope) still remains. They are seriously considering starting dumping that into the sea.

[nctnico]

I only hope that these tanks can withstand the next big earthquake.

Well, they are not that bad actually. That water is processed to remove contamination but tritium (hydrogen-3 isotope) still remains. They are seriously considering starting dumping that into the sea.

Tritium isn't very dangerous to begin with because it only emits Beta radiation. Dillute it enough and it doesn't give any problems.

[wraper]

Tritium isn't very dangerous to begin with because it only emits Beta radiation. Dillute it enough and it doesn't give any problems.

But in form of water it can be ingested and deal the damage. It's the same with many other radionuclides, they are basically harmless as long as stay outside of you but once they got inside, they pose a serious danger.

[schmitt trigger]

Many years ago, the Caterpillar company used to post ads where it detailed a tough infrastructure problem, and how it had been actually solved (with the help of Caterpillar machinery, of course!).
The ad would end with the phrase: "There are no simple answers, only intelligent compromises." Or a similar wording.
Which falls right into the topic we are discussing.

There is no question that electrical energy is one of the essential pillars of modernization. As humanity evolves, the per capita energy demand is and will be increasing.
The problem is compounded by the fact that the World's population is still growing, and that population segments that previously required little or no electrical energy, are now connected to the grid.

The end result? An ever increasing electrical demand.
And from all of the very useful topics above, we can conclude that there is absolutely no energy source that is 100% issue free. So to paraphrase Caterpillar's ad, for electrical power generation and distribution there are, and there will be no simple answers, only intelligent compromises.

Which essentially means that a mix of ALL the power sources will have to be used in the foreseeable future: Coal, oil, gas, geothermal, tidal, hydro, wind, solar and of course nuclear.
How much of each? How to minimize the environmental impact? Responding to those questions my friends, is precisely the not-so-simple-answers.

[Berni]

The reason that tritium is not so bad is that organisms don't hang on to it as much as things like strontium.

The calcium that is used to build bones is not so common in our food, so the body tries to grab any that it comes across and use it to build bones. But because strontium is chemically pretty similar to calcium it goes trough the same biological mechanism and builds bones just fine too. So once it gets in it will stay there. To make things worse sea life does the same thing, concentrating the hazardous isotopes but later on get caught by fisherman that then eat them and get a large dose of these isotopes.

The form of tritium that's problematic is the one that ends up replacing hydrogen in water. Very hard to separate from normal water because it acts just like water, the body uses it just like water too so it does hang around inside of you. But the difference is that humans give off a lot of water, most of the water you consume ends up coming back out in days or weeks as humid breath, sweat. urine..etc so if you happen to consume tritium contaminated water it will simply pass back out of you and tritium levels gradually falling back to nothing after drinking normal water again for a while. Unlike the strontium that will likely stick around in your body to your grave.

One use for tritium water is tracing underground water paths. They dump some of that radioactive water into a stream or cave and then test all the water ways around the area for tiny amounts of tritium with very sensitive equipment. Of course they don't dump large amount of it in, just enough for the equipment to detect.

[nctnico]

Tritium isn't very dangerous to begin with because it only emits Beta radiation. Dillute it enough and it doesn't give any problems.

But in form of water it can be ingested and deal the damage. It's the same with many other radionuclides, they are basically harmless as long as stay outside of you but once they got inside, they pose a serious danger.

That is not correct. Tritium is only dangerous in large quantities. The limits for Tritium in drinking water aren't zero. The WHO advises a limit of 10000bq/l for drinking water.

[KaneTW]

Tritium isn't very dangerous to begin with because it only emits Beta radiation. Dillute it enough and it doesn't give any problems.

But in form of water it can be ingested and deal the damage. It's the same with many other radionuclides, they are basically harmless as long as stay outside of you but once they got inside, they pose a serious danger.

You're confusing things. Alpha radiation is only dangerous inside. Beta and gamma are dangerous both in and outside.

Tritium decays by beta emission, so it's dangerous both in and out. Of course, the total dose you receive when you ingest it is larger. That's a secondary effect.

On the other hand, Polonium-210 (to take a famous alpha decaying nuclide) is harmless outside your body but delivers a lethal radiation dose in less than a microgram when ingested or inhaled.

[wraper]

Tritium isn't very dangerous to begin with because it only emits Beta radiation. Dillute it enough and it doesn't give any problems.

But in form of water it can be ingested and deal the damage. It's the same with many other radionuclides, they are basically harmless as long as stay outside of you but once they got inside, they pose a serious danger.

You're confusing things. Alpha radiation is only dangerous inside. Beta and gamma are dangerous both in and outside.

Tritium decays by beta emission, so it's dangerous both in and out. Of course, the total dose you receive when you ingest it is larger. That's a secondary effect.

On the other hand, Polonium-210 (to take a famous alpha decaying nuclide) is harmless outside your body but delivers a lethal radiation dose in less than a microgram when ingested or inhaled.

Nope, it's you confusing things.

Given its low energy beta emission and corresponding short range in air (6 mm), tritium poses a health risk only when ingested, inhaled or absorbed through the skin.

[KaneTW]

Hmm. I see, it's a specific case of the beta emissions being low energy. Doesn't apply to general beta decay though.

[Berni]

Well the notion behind beta radiation being more dangerous is that these beta decays usually happen at very high energy.

The higher the energy of that shot out beta electron the farther it will get before it stops. The really high energy stuff can get deep into things before it stops so it can easily make it deep into your body from just standing next to it. Metals in general tend to be very effective at stopping beta particles, human flesh not so much.

The one that is a real bastard to stop is Gamma rays. Those are just really high energy electromagnetic waves that will basically go trough anything. Thick lead shielding is needed to keep those back. But they have so much penetrating power that they actually start becoming a bit safer again. Flesh is so bad at stopping them that most very high energy gamma rays can pass straight trough you and keep going without doing anything. For this reason X-Ray machines have the X-Ray tube behind a metal window that stops the low energy gamma rays and only lets the high energy ones come trough and hit the patient. This reduces the radiation exposure while providing a image that is just as good. And this is why they sometimes cover parts of you with a ridiculously heavy lead blanket as its the only thing that will stop those high energy rays.

[vad]

The one that is a real bastard to stop is Gamma rays. Those are just really high energy electromagnetic waves that will basically go trough anything. Thick lead shielding is needed to keep those back. But they have so much penetrating power that they actually start becoming a bit safer again. Flesh is so bad at stopping them that most very high energy gamma rays can pass straight trough you and keep going without doing anything. For this reason X-Ray machines have the X-Ray tube behind a metal window that stops the low energy gamma rays and only lets the high energy ones come trough and hit the patient. This reduces the radiation exposure while providing a image that is just as good. And this is why they sometimes cover parts of you with a ridiculously heavy lead blanket as its the only thing that will stop those high energy rays.

Gamma rays and X-rays are not the same thing. While they both are types of electromagnetic radiation (together with radio waves, infrared radiation, visible and ultraviolet light), gamma photons have more energy than X-Ray photons. The higher the energy of gamma and X-ray photons, the lower crosssection they have when interacting with normal matter (atoms). The lower the crosssection - the lower absorption rate of rays passing through matter - the higher penetration power of the rays.

So, while you can safely shield yourself from X-rays by a thin layer of lead (like they do during medical X-ray imaging), don’t expect same efficacy when shielding from gamma radiation produced during gamma decay of many isotopes. You need walls of lead as thick as 0.5-1.0 meter, to get any reasonable protection.

[KaneTW]

No, both statements are wrong.

X-rays and gamma rays can have overlapping energy ranges. Gamma rays are emitted by the nucleus whereas X-rays are emitted outside the nucleus.

The amount of shielding depends on the intensity, and half an inch of lead will attenuate 50% of 2MeV EM radiation, or 100% of <300keV (e.g. https://www.eichrom.com/wp-content/uploads/2018/01/gamma-ray-attenuation-white-paper-by-d.m.-rev-4.pdf)

Nothing needs meter thick lead walls unless you work with monstrously powerful linacs. Most labs just use ~5cm thick lead bricks.

[apis]

The most extreme form of gamma rays/x-rays radiation is cosmic rays which can have energies as high as 3*10²⁰ eV (about 50 J)! (Which is part of why it was so ridiculous that people were afraid of the high energy collisions at the LHC, cosmic rays can have many million times the energy).

[Berni]

Okay yes i do agree i shouldn't have called radiation from an xray tube gamma rays because they don't originate from radioactive decay.

But the energy level has nothing to do with it being called gamma or x rays. Tho it appears astronomers are calling ones below 100 keV X-Rays while calling the rest Gamma rays, simply for the reason that x ray tubes don't produce such high energy radiation. Yet this high energy radiation often comes from things that is not nuclear decay, but instead as antimatter annihilation, high energy colisions and other violent physics events. So technically they should be called x rays. All depends on who you ask.

In any case the result is the same sort of electromagnetic radiation and its a stubborn little bugger to stop.

And you do indeed see meters of special dense concrete around very powerful particle accelerators. There are scientists working around the place while its running, so they really want to make sure they don't let too many of those rays escape.

[vad]

X-rays and gamma rays can have overlapping energy ranges. Gamma rays are emitted by the nucleus whereas X-rays are emitted outside the nucleus.

Lol. That is a very entertaining (and completely wrong) definition of bands of electromagnetic spectrum. If physicists were to define bands by the emission source, they would have run out of letters of Greek alphabet. Even worse, in case of gamma-ray bursts, the source and the mechanism that produces the burst is unknown. Are you saying astronomers are not allowed to call gamma-ray burst the gamma-ray bursts?

The amount of shielding depends on the intensity, and half an inch of lead will attenuate 50% of 2MeV EM radiation

Intensity of radiation is not the same as the wavelength / energy of individual photons. One hairy guy got Nobel Prize in Physics for his 1905 paper on this topic.

PS. And to attenuate 2 MeV gamma rays by the factor of million you would need 0.25m thick lead wall. For higher energies and higher attenuation - the wall has to be even thicker. So what’s your point here?

[Kleinstein]

The original definition of x-ray and gamma ray is indeed from the source (electrons vs nucleus). However gamma ray is sometimes also used for just EM radiation with very high energy (e.g. > 100 keV).  Many gamma ray sources are relatively high energy (e.g. 100-500 keV range), however there are also low energy ones. AFAIK there is even one example know with gamma rays in the near IR spectrum.

Tritium is special in that it emits very low energy beta radiation.  So it is stopped as easy as the usual alpha radiation. In addition the activity measured in Becquerel does not care about the energy, but just decays. So a lot less (e.g. 10-100 times) energy released from tritium than most other isotopes at the same level of activity.  This results in different (higher) activity limits for tritium in many cases.

Other isotopes sending out beta radiation often also emit gamma radiation - there are very few pure beta emitters.  For the reactor the Cs137 is such a combined beta and gamma emitter. The danger if ingested is more due to the beta radiation, but when checking for contamination one usually measures the gammer emissions. Also externally (e.g. now at Fukushima) the gamma part could well be the more problematic part.

[vad]

The original definition of x-ray and gamma ray is indeed from the source (electrons vs nucleus)

That’s an old archaic definition.  Over the past century great many sources of high energy photons have been discovered that don’t fall into this simplistic electron vs nucleus source pattern: annihilation of particle-antiparticle pair (other than electron-positron pair), high energy collisions in particle accelerators (other than collisions of electrons or nucleus), gamma-ray bursts, x-rays emitted by matter that surrounds and is ejected from neighborhood of black holes, etc. Defining bands by wavelength is a proper way of describing EM spectrum.

[apis]

I think gamma radiation just means em-radiation (originally at least). People categorised radiation as alpha, beta and gamma, where alpha is helium ions, beta is electrons and gamma is em waves, based on how it behaved (electric charge for one thing). (Now we also know of neutron radiation, but it's not called delta radiation). Later people understood that there's a whole range of phenomena that are all just em-waves of different wavelengths.

[jmelson]

The most extreme form of gamma rays/x-rays is cosmic rays which can have energies as high as 3*10²⁰ eV (about 50 J)! (Which is part of why it was so ridiculous that people were afraid of the high energy collisions at the LHC, cosmic rays can have many million times the energy).

Cosmic rays are ions (atomic nuclei) at very high energy, apparently coming from supernova and similar violent galactic events.  When these hit the atmosphere, they produce showers of charged particles and gamma rays that rain down on the surface.

So, while a cosmic ray SHOWER does PRODUCE gamma rays, the "cosmic ray" itself is not a gamma ray.  Yes, being pedantic.

Jon

[jmelson]

Nothing needs meter thick lead walls unless you work with monstrously powerful linacs. Most labs just use ~5cm thick lead bricks.

Well, also particle accelerators can produce protons and neutrons.  These can penetrate remarkable amounts of shielding.
I work occasionally at some particle accelerators.  Most have at least 1 m of shielding, and I think it is mostly for the Proton/Neutron problem.
One facility (HIMAC in Chiba, Japan) had over 2 M thick walls, and they also had beam stops inside the vaults that were about 2 m thick, with steel plates plus concrete, in ADDITION to the shield wall.  Then, they'd place a chunk of aluminum right where the beam came out as it would degrade the neutrons a bit better, I think.  The HIMAC was used during the day for cancer therapy, and generally ran Carbon ions at 1 GeV.

We did have a situation at the Notre Dame tandem linac when running protons at about 10 MeV where they went through the shield wall and caused alarms to go off in the next vault.  That was going through at least 1 m of concrete.

Jon

[KaneTW]

Accelerated protons and neutrons are a wholly different beast and yeah, those penetrate pretty far I believe.

[nctnico]

That is not what they taught me in physics class. Protons and neutrons are very large particles and therefore have a limited penetrating ability.

[KaneTW]

They don't, at normal speeds. At significant fractions of c they just poke a hole. (https://indico.gsi.de/event/6912/material/slides/)

[Berni]

That's a very interesting PDF.

Never seen it explained what happened if something gets in the way of a particle accelerator beam. I did expect it to do some damage but i didn't think it would near instantly drill and cut trough things so quickly and destructively like some sort of fictional giant laser in movies.

[borjam]

That's a very interesting PDF.

Never seen it explained what happened if something gets in the way of a particle accelerator beam. I did expect it to do some damage but i didn't think it would near instantly drill and cut trough things so quickly and destructively like some sort of fictional giant laser in movies.

https://en.wikipedia.org/wiki/Anatoli_Bugorski