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Anton van der Merwe's avatar

Solar power is fantastic and it is great that it is cheap. However the intermittency problem has not been solved. While it is conceivable that storage could be provided for hours and days using batteries, it will still be very expensive and require vast increases in mining, at least with current battery technology. It is possible, but not certain, that future battery technology will solve this problem.

A much more difficult problem is seasonal storage, which is needed in areas where there is very little sunshine in winter. Here there is no affordable solution yet. It is possible that hydrogen and synthetic fuel synthesis powered by solar will solve the problem, but we do not know that yet.

Given these uncertainties, it seems rash to abandon nuclear energy just because we think it may not be necessary. If the problems above are not solved or are very expensive to solve we are doomed to continue using fossil fuels or have much lower standards of living because of higher energy costs.

It relatively trivial, at least from an economic perspective, to make nuclear energy cheaper.

All that is needed is to make the regulations governing radioactivity more rational, using widely accepted data to guide this. I am qualified to write this a medical researcher who researches and teaches mechanisms of disease, including cancer.

There are four ways that the health risks of radioactivity are exaggerated.

(1) The first way is assuming the linear no-theshold (LNT) model is correct. The risks of radioactivity are currently calculated based on data that we have for harm at high doses extrapolated down to low doses. This assumes that risk decreases in a linear way with dose and that there is no threshold dose below which there is no harm. This linear no-threshold (LNT) assumption remains unproven but is probably impossible to disprove for the simple reason that the effects are so small at these low doses that they cannot be measured in any feasible real-world study. In my view there is no point in arguing about whether the LNT model is correct or not. I think, however, we can all agree that assuming the LNT model is correct is cautious.

(2) The second way that the risks of radioactivity are exaggerated is the assumption that the dose RATE does not matter. Current regulations assume that a dose received in 1 second (eg during exposure to an atomic bomb blast) is equivalent to a dose received in 1 year. We know for a fact that this is incorrect. This is why radiotherapy for cancer is given over many weeks (dose fractionation) rather than as a single dose.

The assumption that dose rate does not matter greatly exaggerates the risk of radioactivity released from nuclear reactor accidents and nuclear waste.

(3) The third way risks are exaggerated is in the ‘safe’ levels that is set by regulators. The widely accepted value for calculating the risk of radioactivity is that exposure to 1 Sievert (Sv) increases mortality by 5.5%. The safe level for public exposure to radioactivity is 0.001 Sv/year (1 mSv/year) above background. Assuming the LNT model is correct, this dose would increases mortality by (5.5/1000)% or 0.0055%. This is so low that it is impossible to detect, which is why the LNT model can never be disproved.

For comparison, the ‘safe’ level set by regulators for exposure to the most harmful form of air pollution, PM2.5 particles, is 5-15 ug/m^3. At this level PM2.5 air pollution increases mortality by 0.7%.

This is ~130 fold higher than the estimated mortality rate at the ‘safe’ level of radioactivity. In other words, our regulations value a life lost to radioactivity at least 100 times more than a life lost to air pollution.

This favours forms of energy that produce air pollution by burning stuff, such as fossil fuels and biofueld. Given that we are desperately trying to reduce fossil fuel use to avoid catastrophic climate change, this regulatory difference is unfortunate.

(4) The fourth way the risk of radioactivity are exaggerated is how regulators are required to treat breaches of the ‘safe’ limits. They treat breaches of radioactivity ‘safe’ levels far more seriously than breaches of air-pollution ‘safe’ levels.

One example is how regulators and public health officials respond when these levels are exceeded. When radioactivity from a nuclear reactor accident exceeds the safe levels, people are often forced to evacuate the area, often permanently. In contrast when PM2.5 air-pollution exceeds safe levels evacuation is not required. At most people are advised to stay indoors. One consequence of this disparity is that those forced to move from the Fukushima exclusion zone who were placed in cities like Tokyo were placed under greater overall risk of death because of higher air pollution.

A second example is how regulators require nuclear reactors to be built with numerous redundant safety mechanisms in an attempt to ensure that they never release radioactivity that breaches the ‘safe’ level, even after the worst possible (and thus unlikely) disaster. In contrast regulators do NOT require those building or operating machines (e.g. vehicles, fireplaces) or facilities (power plants, incinerators) that produce air pollution to ensure that humans are never exposed to air pollution levels that exceeds the ‘safe’ limits. Instead the ‘safe’ limits of air pollution are set as something to comply during normal operation of these machines or facilities. There is no expectation that they be designed such that the limits will not be breached even in very unlikely accidents.

This is discrepancy is particularly strange given that, as note above, the safe limit for radioactivity is at least 100 fold more cautious than the safe limit for air pollution. Regulators should, if they were rational, be far more relaxed about breaches of radioactivity limits than about breaches of air pollution limits.

Of these 4 forms of caution, the one most often debated is the LNT assumption. This is unfortunate as it is the only one that it is likely impossible to disprove. The other 3 are more easily shown to be too cautious.

What to do?

Since the safe limits for exposure to radioactivity are incredibly cautious/conservative (see 1-3), we should treat these limit the same way we treat safe limits for air pollution. They should be limits to aim for when a nuclear reactor is operating normally and when nuclear waste storage facility operates as designed under normal circumstances. Since exceeding these limits will not create significant risks, there is no obvious need to try to ensure nuclear reactors never have accidents or that nuclear waste never leaks. We do not do this for machines/facilities producing air pollution even though the safe limits are far less conservative.

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Jason's avatar

Do we really need to decide in advance between nuclear and solar? With all of the different comparable energy jurisdictions around the world and even within North America it seems to me that we can watch and assess various real-time experiments with different mixes unfold and take our lessons accordingly. If solar + storage can out-compete nuclear, great. If not, also great (though solar-powered generation including wind is better when it comes to forestalling the waste heat problem that arises with 100x (!) energy use).

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