A politician asks: can thorium be profitable for Norway?

It will be profitable when done with the right reactor design. Today's PWR, BWR, designs are too expensive. E.g. Hinkley C in Britain is horrendously expensive. ThorCon (a startup company aiming to make molten salt reactors (MSR), using thorium), reckon they can make a safer reactor, within 6 years, for 20% of Hinkley C prices. ThorCon are not unique. There are a host of other startups and molten salt reactor designs: Transatomic Power, Terrestrial Energy, Seaborg Technologies, Flibe Energy, Moltex SSR, Chinese designs, the Russian MOSART, the EVOL MSFR in France, Japanese, and Czech reactors. Bill Gates TerraPower are said to be working on a molten salt reactor too.

Note:

1. There are 3 practical nuclear fuels (fissile materials): plutonium-239, uranium-235, and uranium-233 (Pu-239, U-235, U-233).
2. Uranium consists of a natural mixture of two isotopes: U-238 : U-235, in a ratio of 1000 : 7. Only U-235 is fissile. It must generally be concentrated 5 times (or more) to be used as fuel. In a reactor some of the U-238 "breeds" to Pu-239. U-235 is the only naturally occurring fissile material.
3. There is about 3½ times more thorium available in the world than uranium. Thorium can be 'bred' to make a kind of uranium not found in nature : U-233. (much like Pu-239 is bred from U-238) U-233 performs better than any other fissile material in a thermal nuclear reactor (and 99%+ of reactors are thermal). This is the reason nuclear engineers love it.
4. A molten salt reactor is a very good natural fit for thorium. Molten salt reactors are also:
   • safer - they do not use water compressed at 80 atmospheres. So the possibility of catastrophes like Chernobyl or Fukushima is eliminated.
   • more efficient - because they operate at much higher temperatures (almost 400ºC above a PWR temperature), they convert more heat to electricity
   • potentially less expensive - the intrinsic safety of a MSR allows many expensive safety boondoggles to be dispensed with.
   • for more see: Advantages of molten salt reactors

The magic of thorium is really uranium-233. Poor uranium-233 had all its limelight stolen by the thorium upstart. U-233 has excellent neutronic performance in the thermal neutron spectrum : 90.3% of neutrons hitting a U-233 atom cause fission and release the atom's energy. Only 7.7% of neutrons are wasted (captured and absorbed). The fission : capture ratio (table below) shows that U-233 is 3.1 times better than Pu-239. I'm measuring this performance in terms of fissionable atoms (and neutrons) wasted. The more that are wasted the more difficult it is for nuclear power to be sustainable. To be sustainable we must be able to breed more fissile material from thorium or uranium-238 than we use up in make energy. The couple: thorium and uranium-233 are sustainable in both the thermal and fast neutron spectra.

In practice, uranium-233 can only be made from thorium. That's why thorium is talked about. But it's really about uranium-233.

The relative performance of 3 fissile materials U-233, U235, Pu-239 under thermal neutron bombardment (aka - in a reactor) :

Thermal cross-section (barn)

	capture	fission	total	% fission	fission : capture ratio
U-233	45	531	576	92.2%	11.80
U-235	99	692	791	87.5%	6.99
Pu-239	269	1025	1294	79.2%	3.81

Now it's not so much that plutonium-239 and uranium-238 don't make a sustainable couple too. They do. But it's U-238 + Pu-239 for the fast neutron spectrum only, but thorium-232 + U-233 for either the fast or thermal neutron spectra.

"Hey, these guys had a pretty good idea. Let's go back to it."

Alvin Weinberg MSR Questions (2004). Youtube link

Dr Laurence Miller: One of the things that I considered was the choice between the liquid metal fast reactors and ...

Alvin Weinberg: [Interrupting] Excuse me. How do you increase the volume in here?

Dr Laurence Miller: You mentioned where did we go wrong. And one of your aims was the molten salt reactor and instead of that we went for the liquid metal reactor. Do you think that was a serious mistake?

Alvin Weinberg: Yes I think it was a mistake but, I guess, what I'm talking about goes much beyond the kind of reactor that we're going to build, or that will take over. Because no matter what kind of reactor you build, apprehensive members of the public, or Ralph Nader for that matter, will be able to use this confusion between phantom risk and real risk to scare people out of nuclear energy. So ... I think that that issue overrides the question of whether molten salt is better than liquid metal. I happen to think that molten salt is better than [liquid] metal.

Moderator: I have a follow-on question from cyberspace that we got by email right before today's colloquium and its related to Dr. Miller's question. This question comes from Kirk Sorensen who is with the NASA Marshall Space Flight Center and it has to do with the molten salt breeder reactor. He would like for you to comment on the inherent safety of the molten salt reactor and how we might be able to restart a molten salt reactor programme.

Alvin Weinberg: The molten salt people, who included most famous figures nuclear energy, in particular Eugene Wigner, are all dying off and once they're dead then I suppose you can reinitiate a program on molten salt. Are molten salts inherently safer than liquid metal fuel pin reactors? I think they are, as much as anything, because you don't have supercritical amounts of uranium involved in the system. You add uranium, bit by bit, as you need it because the material is molten. But I'm much impressed with the fact that, despite molten salt reactors having in a sense been a failure in that we don't have people building molten salt reactors now, the molten salt reactor experiment, which produced seven and a half megawatts of heat was one of the most important, and I must say brilliant achievements of the Oak Ridge National Laboratory. And I hope that, after I'm gone, people will look at the dusty books that were written on molten salts and will say "Hey, these guys had a pretty good idea. Let's go back to it."

Radon is not nearly as scary as the authorities make it out to be.

Under normal circumstances, radon is not a threat to your health. No matter what the EPA tell you. There's no positive correlation between lung cancer rates and the distribution of background radiation. Radon-222 is a decay produce of radium-226, which is a decay product of uranium-238. Radon is a heavy gas which accumulates in homes and offices. According to the EPA it is a huge threat to life. In reality it is not such a big threat. It can easily be demonstrated that the effect of other background radiation on the lungs (e.g. from carbon-14 and potassium-40 decay) greatly exceeds the effect of radon-222 by about 100 to 1. So according to EPA logic there should be 100 times as much lung cancer due to potassium-40 and carbon-14 (compared to their projected radon cancers). There's not. There is no good evidence that, at the low doses found, radon-222 causes any measurable lung cancer. The EPA's worry about radon is based upon a projection of a bad mathematical model.

If anything, a map of the USA shows a negative correlation between radon concentration and lung cancer!

Perhaps better described as a positive correlation between radon concentration and no lung cancer!

For an average 70kg person:

• Your lungs weigh approximately 1.3 kg; 1.86% of your body.[1]
• We experience about 8300 Bq of radiation (mostly K-40 and C-14).[2]
• It follows, our lungs experience about 158 Bq (mostly K-40 and C-14).
• When doing mild activity, we breath about 14 litre/minute = 2.3 × 10^-4 m³
• US average radon air concentration is 37 Bq m^-3 (EPA).[4]
• It follows that a US citizen's lungs are exposed to 37 × 2.3 × 10^-4 = 0.00863 Bq radon

When accounting for the effect of that radon on the body we should assume it follows the main decay chain. That's because the other branches of the decay chain have very low probabilities. The main radon decay chain is shown below. It has 4 alphas in it [5]:

		energy (MeV)	½-life
Rn-222 → Po-218	(alpha)	5.59	3.8235 d
Po-218 → Pb-214	(alpha)	6.002	3.1 min
Pb-214 → Bi-214	(beta, gamma)	1.024	26.8 min
Bi-214 → Po-214	(beta, gamma)	3.272	19.9 min
Po-214 → Pb-210	(alpha)	7.687	164.3 µs
Pb-210 → Bi-210	(beta)	0.064	22.2 y
Bi-210 → Po-210	(beta)	1.163	5.012 d
Po-210 → Pb-206	(alpha)	5.305	138.4 d

To convert to millisievert we need to weigh the decays. I won't convert to millisievert but we will weight radon far more heavily than other natural radiation experienced in our lungs. Comparing the effect of radon with other radionuclides we experience: mostly potassium-40 and carbon-14. When converting from grays to millisievert the weighting is normally:

alpha	beta	gamma
20	1	1

Because the EPA are so worried about radon, I'll assume they must know something I don't. So I will weight it twice and also assume every decay in the main decay chain counts. The main radon decay chain is worth 86 according to normal weighting. 4 alphas, 4 betas, and 2 gammas = 20 x 4 + 4 × 1 + 2 × 1. I'll double that to 172. Let's compare the lung radiation contribution of radon with K-40 and C-14:

radon	= 172 × 0.00863	= 1.5
K-40 and C-14		= 158

The effect of K-40 and C-14 combined is about a hundred times that of radon. [even after I weighed radon twice as much as I should have!]

The following table shows the radioactivity found in a typical adult human body of 70,000 grams (about 154 pounds)[2]:

Nuclide	Total Mass	Total Activity (Bq)
Uranium	90 µg	1.1
Thorium	30 µg	0.11
Potassium-40	17 mg	4,400
Radium	31 pg	1.1
Tritium	0.06 pg	23
Polonium	0.2 pg	37
Carbon-14	20 pg	3,840
Total:		8,302
Source: Radionuclides in the Ocean

References

1. Lungs (Wikipedia)
2. Radionuclides in the Ocean
3. Radon decay chain
4. Radon (Wikipedia)
5. Radioactive series of radium-226
6. EPA: The National Radon Action Plan
7. Mohan Doss comment on radon at 'The Conversation'

Postscript

I said "perhaps better described as a positive correlation between radon concentration and no lung cancer!". Here it is:

When "saving money" costs you two hundred fold more than you save.

I sometimes hear we can't afford to spend R&D money on MSRs. The best reply to that is we can't afford not to spend energy R&D.

85% of the world's reactors are PWRs, which operate with a thermodynamic efficiency of only 32% [only 32% of heat energy is converted to electricity]. MSRs can run at 750°C, giving a potential thermodynamic efficiency of up to 48%. Half as much again. Current power reactors make about 2370 TWh of electricity per year. The wholesale price of British electricity is about £40/MWh; making the world wholesale value of nuclear electricity about £95 billion/year. Compared to what MSRs could give we're throwing away £47 billion each year as heat which could've been made into extra electricity. All for the one time cost of £1 billion/£2 billion R&D we didn't spend to make MSRs real.

The US molten salt reactor experiment, MSRE, cost $5 million per year. Not the billions anti-nuclear power campaigners claim. Adjusted to today's money it works out at $30.52 pa., or £21.48 pa. Over 15 years that would cost Britain a total of $322 million.

Cost of R&D avoided: About half as much again as world electricity sells for, say: £47 billion (at wholesale prices)

Ref

• US Inflation Calculator says: US inflation was 511%, from 1970 to 2016

How much krypton-85 leaks into the atmosphere each year?

A recent paper estimated krypton-85 activity in a cubic metre of air at 1.31 Bq. See: Variability of atmospheric krypton-85 activity concentrations observed close to the ITCZ in the southern hemisphere.

Measurements between August 2007 and May 2010 covered three wet seasons. The mean activity concentration of krypton-85 measured during this period was 1.31±0.02Bqm^-3. A linear model fitted to the average monthly data, using month and monsoon as predictors, shows that krypton-85 activity concentration measured during the sampling period has declined by 0.01Bqm^-3 per year.

The measurement, done over 3 years found krypton-85 levels were stable. neither increasing nor decreasing by much. I'll assume that krypton-85 released in balanced by decay.

How much krypton-85 could there be in the atmosphere?

The surface density of air = 1.217 kg/m³
Total mass of the earth's atmosphere = 5.1 × 10¹⁸ kg
Let's assume 1.217 kg/m³ of surface air has a krypton-85 activity of 1.31 Bqm^-3
Let's next assume that krypton-85 activity is the same throughout the air. This will overestimate krypton-85 because its heavier than air. It's almost twice as heavy as carbon dioxide.
Proceeding with our over-estimation. Total activity of Kr-85 in all the atmosphere:
= (1.31 Bqm^-3) × (5.1 × 10¹⁸ kg) / 1.217 kg/m³
= 5.49 × 10¹⁸ Bq

The Specific Activity of krypton-85:
= 400 (Ci/g) [Ci = Curie]
= 1.48 × 10¹³ Bq/g

So our over-estimation for the amount Kr-85 in earth's atmosphere:
= (5.49 × 10¹⁸ Bq) / (1.48 × 10¹³ Bq/g)
= 3.71 × 10⁵ g
= 371 kg

How much krypton-85 is made each year

Krypton-85 is about 0.3% of fission products. Let's assume there is 400 GWe of nuclear reactor capacity on earth. That a 1GWe NPP operating over a year produces just less than 1 ton of fission products. Let's call that 400 tons fission products per year for all the world's reactors. That's works out at 1200 kg of krypton-85 made each year.

But all of krypton-85 does not leak into the atmosphere. Most of it is in sealed casks. The amount that leaks must be about the same as the amount that decays.

t_½(Kr-85) = 10.7 years
λ(Kr-85) = 0.693 / 10.7 years = 0.064766355 years^-1

How much Kr-85 is left after 1 year:

Fractional proportion at time t = N(t) / N(0) = e^{-λ t}
= e^{-0.064766355 years¯¹ × 1 years}
= e^-0.064766355
= 0.93728643

How much Kr-85 leaks?:

= 371 kg × (1 - 0.93728643)
= 23.27 kg

Note: Estimating the amount of fission products made/year

This depends upon the total capacity of all the world's nuclear reactors. There are:

• 435 commercial nuclear power reactors operable in 31 countries, with about 375 GWe of total capacity.
• 180 nuclear reactors power some 140 ships and submarines.
• 240 research reactors

I'll assume an average of 50Me per research and/or sea vessel reactor. So 420 × 50 = 21 GWe of small reactors. Let's round that to 400 GWe capacity for all reactors.

How green anti-nukes closed a power plant delivering 620 megawatts of non-carbon electricity

Vermont Yankee was an electricity generating nuclear power plant, located in the town of Vernon, Vermont, USA. It generated 620 megawatts (MWe) of non-carbon electricity at full power. In 2008, the plant provided 71.8% of all electricity generated within Vermont, amounting to 35% of Vermont's electricity consumption.

1. In May 2009, Vermont created the first statewide renewable energy feed-in law.
2. Entergy requested a new state "certificate of public good" (CPG), but the Vermont legislature voted in February 2010 against renewed permission to operate.
3. In 2011, the Vermont Electric Cooperative utility rejected a contract to buy Vermont Yankee power at below market rates:

   The board of directors at the Vermont Electric Cooperative, the third biggest power distribution company in the state, voted nine to one to reject a 20-year offer from Entergy to buy power from the 39-year old nuclear plant at below market prices.

   Their decision follows the lead previously set by Green Mountain Power and Central Vermont Public Service:

   "I really think today was a referendum on Entergy's relationship with the state of Vermont. In fact, we as a management team got a clear message not to speak with Entergy again"

   -- Dave Hallquist VEC CEO
4. On 29 December 2014, Vermont Yankee owner Entergy ceased the plant's operations.
5. Now the renewables advocates admit they can't provide renewable energy because the laws of physics just aren't right for the universe they live in.

   "Unless we get cost-effective storage, we can’t meet those goals — it’s a law of physics. The reason is because we’re trying to meet 100 percent of our annual energy needs with these projects that produce only 15 percent of the time. So you end up having to build six times the amount, and you end up having more generation than load, so there’s nothing you can do about it. We can’t meet our goals with the current physics."

   -- Dave Hallquist, CEO of VEC Vermont Electric Cooperative

The Hinkley Point deal is prohibitively expensive

So say the Guardian, again, today. It's not "prohibitively expensive" but it is "too expensive". Hinkley Point deal is too expensive is the common doxa, among both nukes, anti-nukes, and neutrals. The question of expense has interested me for sometime. Why so expensive, what can be done about that?

The AREVA EPR is the only modern reactor design currently approved by our regulator: Office of Nuclear Regulation (ONR). If we want a reactor right now, this is the only one we can build. Had we more choice, we could build nuclear power plants for much less than this. Probably about half the price. [KEPCO build their APR1400 reactors in UAE for £3¼ billion each] So why don't we? Given the EPR design is the only one with a current UK GDA, the obvious question to ask is: what's holding up the UK GDA process? The obvious answer is often: lack of resources. But what resources?

Government framed the UK nuclear reactor regulatory process to discourage vendors from applying for reactor approval and spent no effort encouraging vendors to apply to get reactors approved. In effect, that's how current regulation works in the UK. There was no design nor malice in this, just the habit government have of copying what seems to work elsewhere. UK government, basically, copied the US model (how US funds their NRC : Nuclear Regulatory Commission). NRC funding works reasonably well in the USA because it's a big country. US electricity demand is 11 times UK's. Because US population is 5 times ours, and per capita electricity use just over twice ours. After a US reactor GDA application is approved, the reactor vendor has reasonable confidence that many will be built. That allows Americans to justify the up front costs of gaining NRC approval. Not so in the UK. A vendor trying to build reactors here can't expect many of their reactors to be built here at all. The market for new builds is just not that large.

Electricity requirement of UK / US

	Average demand (GW)	Per capita use (kWh)	Population
US	463	13,010	320 million
UK	42	5,958	64 million

UK Government framed legislation such that a large fee, probably about £40 million, is charged up front for reactor approval. This is large enough to discourage vendors putting their designs forward for GDA validation. That, and the 5-year approval period. The UK GDA process began in 2007 with 4 competing designs: the AREVA EPR (PWR), the Toshiba-Westinghouse AP1000 (PWR), the GE-Hitachi ESBWR (BWR) and the AECL ACR1000 (Candu). The ESBWR and the Candu designs were withdrawn, leaving only 2. The AP1000 application was later suspended because the submission was not in S.I. units. That left only 1 reactor: EPR. Our system of taxing vendors beforehand led directly to GE-Hitachi pulling their ESBWR design out of the approval process despite spending £20 million on British approval. It partly led to AECL (Candu) not really trying. That might not be so bad in a world with lots of vendor competition. There are only about 7 such vendors in the world: AREVA (France), KEPCO (South Korea), Westinghouse (USA-Japan), GE-Hitachi (Japan), Rosatom (Russia), CANDU (Canada), Various Chinese. Some argue we should not consider Russian and Chinese designs due to security issues. CANDU reactors have positive voids, so many will not want them due to safety issues. That narrows the field down to 4 nuclear reactor vendors! So what other reactors could reasonably have been submitted for UK GDA? KEPCO have perfectly good designs they build at low cost (e.g. the APR1400 in UAE), but they've never been encouraged to apply for a GDA. That despite Britain and South Korea signing a special free trade deal in 2012. AREVA understood that their EPR design was too expensive at a very early stage: nearly 20 years ago. That's why they increased it's capacity from an initial 1100 MWe to 1650 MWe - to mitigate the expense by trying to gain an advantage in scale: in theory the cost of building and running 2 giant reactors being lower than 3 large reactors. It never panned out that way. Yet AREVA always had other designs it could've submitted for UK GDA. They had the KERENA and ATMEA1 designs too (since 2009 and 2007 respectively).

A better system would've seen the approval fee mostly paid for by a tiny tax on nuclear power, with an up front fee of, say 10% of approval costs. That would force immediate costs on the vendor of ~ £4 million. I think that would've encouraged KEPCO to apply for a GDA on a purely speculative basis. Imagine that it costs £40 million to approve a reactor for UK use. 10 different reactor approvals would cost £0.4 billion. A lot of money. The argument goes: the tax payer shouldn't have to cough up this money. Yet over a 35 year period, during which the Hinkley C contract for difference (CfD) applies, the electricity bill payer will cough up about £35 billion more than they would otherwise pay had their electricity been sourced at the current electricity wholesale price. We pay a tax anyhow. It's just that we're paying a tax at least 50 times larger than need be. Not quite: nearly all new nuclear power plants will need some kind of CfD but we could reasonably expect the difference in CfD and wholesale price to be half what it is for the EPR. So, instead of paying £35 billion more over 35 years, we'd pay £20 billion more over 35 years for a different reactor design.

1. Guardian Live: should we say yes to nuclear power?
2. KEPCO are building their APR1400 reactors in UAE for £3¼ billion each
3. The costs of UK GDA for the AREVA EPR were said to be £35 million in 2012
4. In 2007, GE-Hitachi Nuclear Energy Submitted ESBWR to UK Regulators for Generic Design Assessment (GDA)
5. CfD: contract for difference. A CfD means that the customer pays more for electricity than they would were they paying the market price. It allows new electricity capacity suppliers to recoup their capital costs. Think of it like a mortgage. You buy the house now, live there but it takes you 25+ years to repay the cost.
6. The saga of Hinkley Point C: Europe’s key nuclear decision
7. vendor: I'm using the term vendor here to mean `nuclear power plant design and construction company`
8. GDA = Generic Design Approval. This is like a licence and safety certificate allowing one to build several nuclear reactors in one country.