New Mars Forums

tahanson43206

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Nuclear Battery - Manufactured RTG - Recycled - Neutron recharge

This topic is a spin off of the Nuclear Battery - Electric topic.

The topic was suggested by Calliban, who suggested a search for a material that can be repeatedly recharged to an elevated isotope that is unstable, and which releases energy according to the half-life of the material.

This battery design would produce thermal energy, as elevated isotopes release neutrons to return to more stable configurations.

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tahanson43206

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Re: Nuclear Battery - Manufactured RTG - Recycled - Neutron recharge

The opening post for this new topic was contributed by Calliban:

One option that is worth considering is putting a target of isotopically pure material into a nuclear reactor and irradiating it with neutrons.  The material will absorb neutrons becoming a higher isotope of the element.  If the product isotope is unstable it will release energy as it decays.  The energy would be in the form of beta emissions, gamma emissions and direct thermal energy as the decaying nucleus recoils.  We would want a product nucleus whose decay chain did not emit gamma rays.  Gamma is a shielding problem.

This topic is available for posts about the historical development of RTG.

In addition, detailed technical data about manufacture of RTG devices is welcome and needed.

In opening this new topic, I have limited understanding of how RTG devices are made, so contributions that help with that are welcome.

The idea of Calliban (as I understand it) is to find a material that can be bombarded with neutrons so that it assumes an elevated energy state, and then releases that stored energy over time according to the half-life of the material.  The output of such a device would (presumably) be thermal energy, which can be captured in traditional ways.

The concept that is unique to ** this ** topic is the rechargeable nature of the material.  At present, (and to the best of my knowledge which is limited) no RTG devices are renewable.  All RTG devices (that I know about) are one-time use designs, and for a probe headed to the outer limits of the Solar System, a one-time design is appropriate.

The objective of ** this ** topic is to find a material that can be re-charged by neutrons as often as needed, and for as many times as a particular application may require.  Applications include the full range, from automobile applications through railroad engines and on to ocean going vessels.

The solution found needs to be packaged so that it is safe for use by citizens in ordinary situations.

Safety is a primary concern.

RTG's sent on voyages to the outer Solar System are no danger to humans near by.

A package that emits neutrons to produce thermal energy is going to receive intense study/testing/validation before it is licensed for use in a public application.

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SpaceNut

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Re: Nuclear Battery - Manufactured RTG - Recycled - Neutron recharge

Here is another such topic To RTG or not to RTG the size is the question

tahanson43206

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Re: Nuclear Battery - Manufactured RTG - Recycled - Neutron recharge

For SpaceNut re Post #3

Thank you for showing us the link to the topic from 2017.

That was worth reading from the top.  I'm interested in RobertDyck's discussion of Potassium 40 (for example) and for the use of a magnetic field to accelerate the half lile of decay to Argon 40.

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Calliban

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Re: Nuclear Battery - Manufactured RTG - Recycled - Neutron recharge

I think much depends on what you have in mind for application.  Gamma emitting isotopes produced by neutron activation are commonly used in medicine and industry.  Irradiating Co-59 with slow neutrons produces Co-60.  This is a strong gamma emitter with a 5 year halflife that is used for weld radiography.  I don't think it has ever been used as an energy source.  Cs-137 has been used in RTGs.  It is one of the dominant fission products.  In a shielded sample of radioactive material, any energy that isn't lost as neutrinos will be converted to heat.  But the gamma rays that Cs-137 and its decay products release are valuable.  They have been used for radiography and also in irradiating facilities for sterilising equipment and extending the life of food.

Sr-90 is probably the most promising isotope for an actual battery power source.  It doesn't release gamma rays, so would not require heavy shielding.  And it is otherwise a waste product.  If we ever get nuclear reprocessing going (on Earth or Mars) most long-lived fission products will find useful applications.  This reframes the debate on nuclear waste.  If all of the isotopes have industrial uses, are they still waste?

151Sm is a low energy beta emitter with a half life of 88 years.  It is about 0.5% of fission product yield from 235U fission.  It would make an excellent pacemaker battery, as it won't need replacing in the lifetime of a patient.

Tc-99 is a beta emitter with a halflife of 211,000 years.  It is about 6% of fission product yield.  Technetium is an excellent corrosion inhibitor.  Half life is too long to be useful as an energy source.  Pd-107 has a yield of 1.25% and a halflufe of 6.5Myr.  It could have uses as a catalyst and as a corrosion resistant coating for chemical plant.  The production of nitric acid is carried out in stainless steel vessels, which experience life limiting corrosion.  Pd-107 coatings would extend its life significantly.  Pd-107 couod also be used as coating for nuclear reactor fuel and internals.  Corrosion is a life limiting issue for light water reactors.  A corrosion resistant coating just a few atoms thick, could extend life by decades.

Last edited by Calliban (2023-12-22 12:42:21)

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"Plan and prepare for every possibility, and you will never act. It is nobler to have courage as we stumble into half the things we fear than to analyse every possible obstacle and begin nothing. Great things are achieved by embracing great dangers."

SpaceNut

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Re: Nuclear Battery - Manufactured RTG - Recycled - Neutron recharge

An element that needs to be restored to a charge state requiring a collider does not seem all that particle since that is quite a bit of infrastructure.

tahanson43206

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Re: Nuclear Battery - Manufactured RTG - Recycled - Neutron recharge

For SpaceNut re #6 ....

Your vision of how a nuclear "battery" might be recharged is interesting and worth development.  Please describe how you might use an accelerator (linear or circular) to "re-charge" a collection of atoms to a higher atomic energy?

***
For Calliban ... your suggestion to study Potassium 40 and Argon 40 is appreciated ...

https://radioactivity.eu.com/phenomenon/potassium_40

The paper at the link above goes into some depth, in reviewing the properties of Potassium 40 that make it so useful for geological dating.

Stable nuclei sit at the bottom of a so-called ‘valley of stability’, a concept that helps determine whether a nucleus is radioactive or not. Potassium 40 should be at the bottom of this valley and should be the most stable of the nuclei containing 40 nucleons. Its mass energy (or internal energy), however, is actually greater than either of its neighbours – calcium 40 and argon 40. This difference is enough to make potassium 40 unstable. The reason for this is that protons, like neutrons, like to exist in pairs in a nucleus. Potassium 40 contains odd numbers of both – 19 protons and 21 neutrons. As a result it has one bachelor proton and one bachelor neutron. In both argon 40 and calcium 40, however, the number of protons and neutrons are even, granting them that extra stability.

The very slow decay of potassium 40 into argon are highly useful for dating rocks, such as lava, whose age is between a million and a billion years. The decay of potassium into argon produces a gaseous atom which is trapped at the time of the crystallization of lava. The atom can escape when the lava is still liquid, but not after solidification. At that moment, the rock contains a certain amount of potassium but no argon. With time and the potassium 40 disintegrations, the gaseous argon atoms accumulate very slowly in the lava where they are trapped. Measuring the amount of argon 40 formed since the solidification of the lava allows for an accurate measure of the rock age.

ChatGPT(4) found a reference to a physicist named "Rolf" who (apparently) showed that half-life of a particular substance can be reduced by chilling the substance to near absolute zero.  This observation is reported but apparently there is skepticism about the work.  Apparently the consensus in the scientific community it that the random quantum events cannot be influenced by external factors. However, recently I found a reference indicating that the rate of decay in at least one case case can be accelerated by use of a magnetic field.

The ability to control the release of energy from a system would be helpful.

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Calliban

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Re: Nuclear Battery - Manufactured RTG - Recycled - Neutron recharge

Pottasium-40 has a half life of 1.2 billion years.  It will not be useful as a battery material because power per unit mass is miniscule.  The most useful materials are those with half lives between a few years to several decades.  Also beneficial are low gamma emissions.

Carbon-14 has been discussed as a potential nuclear battery material.  The idea was to make it into synthetic diamonds, rendering it environmentally inert due to the inability of diamond carbon to enter the food chain.  The problem is that C-14 has a halflife over 5000 years.  The decay rate and specific power is low.  But if we needed an energy source to provide heat and power to a long lived interstellar probe during a coast phase, then this would be a contender.

Am241 is also a contender for long lived nuclear batteries.
https://en.m.wikipedia.org/wiki/Americium-241

Decay energy is 5.486MeV and half life is 432 years.  Most of the energy is associated with alpha emission with only 50KeV being yielded by gamma.  This makes handling straight forward.  If we need a battery that will function reliably for 500 years, this would do the job.  It is one of the leading minor actinide wastes produced by slow neutron reactors.  But in a closed fuel cycle, we have the option of finding uses for all of these things.  Am-241 could replace 238Pu as a radiothermal energy source.  We would need about 5x more of it per unit power, because half life is 5x longer.  But it won't do much to increase the mass of a space probe.  For Kuiper belt or Oort cloud missions, this could be a low cost material that would enable a mass produced generic probe to be launched to multiple targets.

Last edited by Calliban (2023-12-23 10:09:23)

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"Plan and prepare for every possibility, and you will never act. It is nobler to have courage as we stumble into half the things we fear than to analyse every possible obstacle and begin nothing. Great things are achieved by embracing great dangers."

tahanson43206

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Re: Nuclear Battery - Manufactured RTG - Recycled - Neutron recharge

For Calliban re #8

Thank you for another substantial contribution to this topic!

A question to be answered (eventually) is what controls the rate of decay of various materials.

It appears that physicists are good at observing half life properties of various materials, but not so good at explaining why a particular atom decays when it does. The hand waving seems to involve "quantum uncertainty" and the Uncertainty Principle is trotted out as the "explanation"

Potassium 40 might make a useful storage medium if the half life could be controlled.

Your other examples are definitely interesting for practical application without managing the decay process.

***

Please keep looking for candidates with half lives a  bit closer to the goal of 1 Mw for 20 years.  A half life of 100 years would yield a reasonable performance for 20 years, at which point the power pod could be swapped and the unit recharged to full capacity and set back out in the field.

On the other hand, if half life can be adjusted, then the range of candidate materials would increase.

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tahanson43206

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Re: Nuclear Battery - Manufactured RTG - Recycled - Neutron recharge

For All ...

This post by SpaceNut shows what this topic is about:
https://newmars.com/forums/viewtopic.ph … 98#p217498

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edit by spacenut

Right now, we have just a material that is giving off heat and while if we get it hot enough to circulate a working media, that will become what can be an electric generator once couple to the heat source.

here is the RTG battery internal. design

Of course, the structure is dependent on temperature that you are striving for.

here is how NASA generates power on mars
https://mars.nasa.gov/internal_resources/788/

tahanson43206

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Re: Nuclear Battery - Manufactured RTG - Recycled - Neutron recharge

To clarify a bit, this topic is about heat delivered to a thermocouple as a traditional way of obtaining electric current from nuclear activity.

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tahanson43206

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Re: Nuclear Battery - Manufactured RTG - Recycled - Neutron recharge

With BARD's contribution, ChatGPT(4) went back to work and it came up with a business plan that looks plausible to my uneducated eye.

For Calliban ... please evaluate the proposal at the bottom of this transcript:
https://docs.google.com/document/d/1545 … sp=sharing

There are many (many!) technical issues to be solved, but what I am looking for here is the top-level feasibility of the concept.

We seem to have a concept with a common material as input, and a highly valued material as output, with steady power production as the immediately salable commodity to offer to the public.

This topic is open to all. However, I would appreciate serious and thoughtful contributions.

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tahanson43206

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Re: Nuclear Battery - Manufactured RTG - Recycled - Neutron recharge

Calliban has added a helpful post to the Ni-63 >> Cu-63 topic...

Assuming that my calculations are accurate, 1 gram of Ni-63 has decay power of 8.5mW.  To produce 1MW of power, the battery would need to contain some 118 tonnes of Ni-63.  That much Ni-63 would be very costly and physically difficult to manufacture.  I would suggest that you think of applications with microwatt to watt power levels.  That might have uses in compact devices that need to function independently of human intervention for long periods of time.

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tahanson43206

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Re: Nuclear Battery - Manufactured RTG - Recycled - Neutron recharge

ChatGPT4 calculated the output of a Ni-63 storage device at 87% after 20 years.

I found an online calculator that verified that estimate:

home / math / half-life calculator
Half-Life Calculator
The following tools can generate any one of the values from the other three in the half-life formula for a substance undergoing decay to decrease by half.

Half-Life Calculator
Result
quantity remains, Nt = 87.055056329612

quantity remains
Nt    initial quantity
N0    time
t    half-life
t1/2

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