Environment & Energy

NNadir

(35,057 posts) Sun Jan 19, 2025, 06:08 PM Jan 19

Something I thought should happen, hoped to happen, actually happened in 2024, some good news.

Last edited Sun Jan 19, 2025, 09:24 PM - Edit history (1)

There is only one type of existing commercial thermal nuclear reactors that can function as a breeder reactor; this is the Canadian CANDU, type reactor, which uses deuterated water (with an extremely low thermal neutron capture cross section) as a coolant. Forty-Six examples of this type of reactor exist in several countries: In Canada, in India (the second largest share after Canada), as well as in Argentina, China and Romania.

However the only nuclide that cause a CANDU to breed is the uranium isotope ²³³U isotope, which does not occur naturally in isolatable quantities on Earth: It is part of the long extinct ²⁴⁹Cf (²³⁷Np) decay chain. ²³³U however can be made synthetically by the ²³²Th[n, gamma]²³³Th reaction (²³³Th t_1/2 = 22.3 minutes) resulting in two beta decays through ²³³Pa (t_1/2 = 26.975 days) to ²³³U. (A molten salt reactor famously did this in the 1960's, but it was an experimental reactor, although while it operated, for about two years, it produced the world's largest inventory of ²³³U which is, to my knowledge, still available at ORNL.)

I have long thought that because of their very high neutron efficiency, CANDU reactors, which run on unenriched uranium, should use fuel containing some thorium, to increase their "burn-up" (the amount of energy produced per unit of mass) to very high levels. In addition, through a fuel cycle, considerable amounts of fissionable plutonium would be generated, along with fissionable ²³³U. This would make the residual fuel very valuable as after the fuel reaches a subcritical regime because of the accumulation of fission products with high neutron capture cross sections, reprocessing to remove these would leave enriched uranium (with ²³³U) that would be ready for use in other thermal reactors around the world, without the use of physical enrichment processes. This would have the effect of making the fuel useless for nuclear weapons, while increasing the rate at which we can provide new reactors with fuel without mining.

Apparently a commercial organization thought the same thing and in fact, manufactured a fuel to do precisely this which is now being tested.

To wit:

Licensing and testing progress for innovative thorium-based fuel

Days after announcing the start of accelerated irradiation testing and qualification of its patented ANEEL thorium and high-assay low-enriched uranium fuel at Idaho National Laboratory, Clean Core Thorium Energy announced it has completed the first phase of the Canadian nuclear regulator's pre-licensing review process.

ANEEL has been developed for use in pressurised heavy water reactors and Candu reactors (its name is taken from Advanced Nuclear Energy for Enriched Life). The company says it can offer significantly improved performance with existing proven heavy water reactor systems by leveraging thorium's "inherently superior" nuclear, thermal and physical properties while retaining the same external dimensions and configuration design as in currently used natural uranium fuel bundles. It can be used to replace current fuel bundles, without any significant modifications to the reactor, to reduce life-cycle operating costs and waste volumes, increase safety and accident tolerance, and result in additional proliferation resistance, the company claims.

ANEEL is the first thorium-based fuel for Candu reactors to successfully complete the first phase of the Canadian Nuclear Safety Commission (CNSC) pre-licensing process for new fuel designs, Clean Core said...

A CANDU reactor using natural uranium has a burn up of considerably less than 10 GWd/ton. (GWd = Gigawatt-days, a unit of energy that is equal to 86.4 trillion Joules.). This results in large volumes of fuel that is relatively dilute in valuable fission products and actinides like plutonium and thus more challenging to reprocess.

The ANEEL fuel can achieve burnups far higher, more than 600% higher:

...The CCTE-ANEEL-1A irradiation experiment is to begin this month and achieve burnup targets of up to 60 GWd per tonne. As each planned burn-up target is achieved, the test capsules containing irradiated ANEEL pellets will be sent to INL's Materials and Fuels Complex for destructive and non-destructive post-irradiation examination.

"Irradiating homogeneously blended thorium and uranium oxide in ATR is a first-of-a kind experiment for INL and the US DOE,", said Michael Worrall, a nuclear engineer at INL and Principal Investigator for the CCTE-ANEEL-1A experiment. "We are excited to see the potential of the ANEEL fuel technology and what the future of this technology holds."

The ATR is a pressurised water test reactor which operates at very low pressures and temperatures compared to a large commercial nuclear power plant to produce large-volume, high-flux thermal neutron irradiation in a prototype environment. The one-of-a-kind reactor can be used to study the effects of intense neutron and gamma radiation on reactor materials and fuels...

Assuming that the United States does not fall into anarchy under incompetent and ignorant leadership, this offers hope for the future and the rapid scale up of nuclear energy.

Have a nice evening.

8 replies

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Something I thought should happen, hoped to happen, actually happened in 2024, some good news. (Original Post) NNadir Jan 19 OP

Good news for us all, I hope. eppur_se_muova Jan 19 #1

It would be problematic if Canada closed the border to US refugees and imports, and decided become self sufficient. NNadir Jan 19 #2

I've given up hope for US leadership in regards to nuclear Vogon_Glory Jan 19 #3

During the Biden administration an era of US nuclear creativity... NNadir Jan 20 #4

That, good sir, was the Biden administration. I have no such faith in Individual One n/t Vogon_Glory Jan 20 #5

I know. Antinuke efforts have always thrived in ignorance. NNadir Jan 20 #6

Indian nuclear John ONeill Jan 21 #7

My recollection is that India has long considered this approach. I just checked in my files... NNadir Jan 21 #8

eppur_se_muova

(38,181 posts)

1. Good news for us all, I hope.

Reply to NNadir (Original post)

Sun Jan 19, 2025, 06:37 PM

Jan 19

Just tell tsf it's a "nuclear" and he'll approve it. Don't mention Canada.

NNadir

(35,057 posts)

2. It would be problematic if Canada closed the border to US refugees and imports, and decided become self sufficient.

Reply to eppur_se_muova (Reply #1)

Sun Jan 19, 2025, 06:38 PM

Jan 19

They probably can; I doubt we could do so.

Vogon_Glory

(9,666 posts)

3. I've given up hope for US leadership in regards to nuclear

Reply to NNadir (Original post)

Sun Jan 19, 2025, 07:08 PM

Jan 19

reactor technologies, but I want to believe that enough developed (and developing) countries will turn away from eithe continued reliance on fossil fuels or hopeful “solar will save us” “solutions” and allow this technology to work out.

NNadir

(35,057 posts)

4. During the Biden administration an era of US nuclear creativity...

Reply to Vogon_Glory (Reply #3)

Mon Jan 20, 2025, 09:47 AM

Jan 20

...not seen since the 1960s was underway.

There were a wide array of exciting teams working on innovative projects.

What will become of it I don't know. We're entering an anti-intellectual hell.

Vogon_Glory

(9,666 posts)

5. That, good sir, was the Biden administration. I have no such faith in Individual One n/t

Reply to NNadir (Reply #4)

Mon Jan 20, 2025, 12:24 PM

Jan 20

NNadir

(35,057 posts)

6. I know. Antinuke efforts have always thrived in ignorance.

Reply to Vogon_Glory (Reply #5)

Mon Jan 20, 2025, 12:46 PM

Jan 20

We are now in an age of the rule of ignorance.

John ONeill

(66 posts)

7. Indian nuclear

Reply to NNadir (Original post)

Tue Jan 21, 2025, 02:43 PM

Jan 21

I understand the CEO of the company developing ANEEL is of Indian origin. If the technology could be transferred to India, which has its own heavy water reactor fleet derived originally from the Candu, it would allow use of India's huge thorium deposits. Tatra Steel is supposed to be working on mass manufacture of the 220 MW version of the Indian HWPR, for combined heat and power in industry, and the US recently approved transfer of nuclear tech and materials to India, after years of banning them.

NNadir

(35,057 posts)

8. My recollection is that India has long considered this approach. I just checked in my files...

Reply to John ONeill (Reply #7)

Tue Jan 21, 2025, 06:22 PM

Jan 21

It appears from this paper, India loaded a PHWR with thorium in 1992: Surendra Mishra, R.S. Modak, S. Ganesan,
Optimization of Thorium loading in fresh core of Indian PHWR by evolutionary algorithms, Annals of Nuclear Energy,
Volume 36, Issue 7, 2009, Pages 948-955.

From the text:

Since thorium is a much stronger absorber than depleted Uranium, it causes stronger flux depressions in its vicinity. This affects the reactivity worth of the two shutdown systems. On the whole, the number and locations of Th bundles have to be chosen so that the following conditions are fulfilled:
(1)
Keff is maximum possible so that reactor can operate without fuelling for longer time leading to better fuel economy.
(2)
The operating limit on channel outlet temperature (299 °C) is obeyed.
(3)
Maximum bundle power is less than 440 KW.
(4)
The reactivity worth of each shutdown device is not less than 30 mk.
The problem of obtaining an optimum distribution of Thorium bundles which satisfies above criteria was solved successfully about two decades ago (Balakrishnan and Kakodkar, 1994) and a suitable distribution consisting of 35 Th bundles was arrived at. This pattern was subsequently loaded in the Indian PHWR at Kakrapar (KAPS-1), which went critical in September 1992. A gradient based method was used to find the solution.

My overall impression is that the Indians intend to use plutonium rather than HALEU to provide the initial reactivity. I think this a superior approach since HALEU relies on enrichment, with which I believe we should do away, since it adds expense.

I discussed my views this point, peripherally, on another website, at which I was a "guest author in 2013, with some reference to Indian CANDUs:"

On Plutonium, Nuclear War, and Nuclear Peace

Note that the 1992 experiment was conducted in a relatively small PHWR, not exactly of the CANDU design. It used natural uranium, like a CANDU, but as the text excerpted hints, reaching full power took some time because of the higher neutron capture cross section of ²³²Th compared to ²³⁸U. The longer half-life of the intermediate nuclide in the thorium case, ²³³Pa (t_1/2 = 26.975 days) as compared to the intermediate in the ²³⁸U case, ²³⁹Np (t_1/2 = 2.356 days) means that the fissionable material takes longer to accumulate in the former case, and thus longer to reach full power.

It seems to me, without any sophisticated analysis, just off the top of my head, that a ternary Th, U, Pu fuel would not suffer from this lag. My son keeps promising to get me access to publicly available neutronics programs, but the little brat hasn't done so yet. He doesn't work with that software himself, as he's in nuclear materials, not fuels, but his girlfriend and one of his best friends do. There are a few zillion examples I'd love to run, but my computational power, and time, are limited.

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