Acronyms used:

LNT stands for Linear No Threshold: cancer risk is directly proportional to dose, that doses are cumulative over time (rate doesn‘t matter), and that there is no threshold or safe dose. This contradicts studies that we have about people who received enough CUMULATIVE doses of radiation that they would be dead if it was at the same time.

ALARA: Radiation should be As Low As Reasonably Achievable. In practice this means that any cost reduction simply means freed money that you're now required to spend on safety.

Yeah, that's utterly stupid. We need to define a value per life saved and apply it across the board to safety regulations. Any safety regulation that comes in cheaper than that is required, no safety regulation that comes in more expensive than that is required. There should be no singling out of industries. All such regulations must include a reasonable description of how it can be done for that cost--which can be challenged in court. Likewise, outside groups can challenge proposals which have been rejected by showing there's a cheaper way to do it. (And this would include companies that stand to benefit. A company that comes up with a cheap enough way to implement a safety measure can get it mandated. While this could cause a monopoly situation they can't exploit it because if they make it too expensive the rule goes away.)

> is that the regulators use the wrong threat model for radiation (LNT)

Nuclear fans like to complain about the LNT, but I don't think they're really thinking this through.

In a nuclear accident, most of the population exposure will be a minor increase spread across a vast population. At those doses, we basically cannot check whether LNT is true or not -- the small cancer incidence it predicts is statistically invisible against all the other causes of cancer.

So foes of LNT want to say "we can't show LNT is correct", which is fine, but then they say "so we must assume the actual effect is smaller, perhaps zero", which is not fine. The evidence doesn't support that second step, and this is not a court of criminal law where radiation must be presumed innocent unless found guilty beyond a reasonable doubt. One might very well argue that one should take a precautionary approach, which is to assume that low level radiation has the worst effect it could have that is not ruled out by evidence. This would imply even larger threat than under LNT.

We know the mechanism by which radiation causes damage: Particles knock into DNA, changing its structure. This causes mutations, and once too many of those accumulate, you get cancer, or your cells just stop working and you die.

This would suggest that the risk should be linear with radiation dose. But cells have DNA repair mechanisms. If a person receives a very large dose in a short amount of time, it makes sense that the repair systems might be too overwhelmed to fix all the damage that has occurred. Of course, the repair system isn't perfect, and some small fraction of damage will be permanent. This suggests that LNT should be true for small doses, but the harmfulness of radiation per particle should increase at larger doses.

A few consequences if that's true:

Depending on how the constant coefficient is determined, a fully linear health risk model will tend to overestimate risk at low dose rates, but underestimate at high dose rates.

This also suggests that radiation concentrated in a particular spot on the body is particularly dangerous. The cells in that location will be bearing the brunt of the radiation dose, so their repair systems are more likely to fail. So inhaling a bit of plutonium dust means you're in for a worse time than absorbing an equivalent dose spread out over your body.

Of course, whatever health risk model we choose, it should also be applied to the regulation of coal plants, since they put radioactive isotopes into the atmosphere as a part of their regular operation.

It's also possible that repair mechanisms can be induced, with the body making more repair enzymes under higher damage load. If so, this would imply the danger from a single particle would be higher at low doses where less induction has occurred. This is radiation hormesis, but of a kind that means LNT could be underestimating the danger of very low doses of radiation.

You could be right, maybe there's a hormetic valley somewhere in the risk curve. I think it still has to be linear close to the background radiation level, and grow faster than linear as one approaches the lethal level, though.

Isn't it true that the proportionality coefficient for LNT was calculated using cancer rates for atomic bomb survivors? The dose for them would be very rapid, and there would be little time for enzymes to be produced. This would explain why such a valley didn't show up in that particular set of data.

LNT has been checked as far down as the statistics lets it be checked (including with animal experiments). Those doses are much higher than the doses I was talking about, the doses that actually matter for nuclear accidents. It's conceivable that the slope of the effect/dose curve at very low doses could be very steep. The results at those higher doses wouldn't be able to tell.

This is great, thank you!

Setting a firm limit on radiation release ahead of time, rather than one based on economics like ALARA just seems like it would be far safer. The other examples also seem like they are bad regulations that don't help safety or construction either. Would be great to see if they could result in more efficient construction.

Another way of setting a limit on radiation would be: 1/10 as much as an average coal plant per kWh. Current nuclear plants are already below this, because coal plants release a fair bit of radioactive material into the air, from trace elements like thorium in coal.

When regulations prevent deploying something 10x safer than the currently deployed alternatives, they're not making us safer.

Nuclear plants may be below this in normal operation, but what matters is the dose in accident scenarios. That's what drives things like containment buildings, which are large and expensive.

It looks like private enterprise is maybe incompatible with Nuclear Power then. I find this to be pleasing, and we should simply side step private enterprise and build public plants.

How did you get that from the linked article? Or are you just shooting from the hip based on bias?