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 Post subject: Lightbridge metal fuel
PostPosted: Mar 02, 2017 5:40 pm 
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Why does Lightbridge metal fuel have much less plutonium on discharge than conventional uranium-oxide fuel?
http://www.ltbridge.com/fueltechnology/ ... technology


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PostPosted: Mar 03, 2017 12:47 am 
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Less uranium to start with? Fuel is only 50% uranium. Also, there apears to be well less than normal amounts of fuel to begin with. That suggests the fuel is WAY more than the typical 3-5% LEU. If the U238 is well less than 50% of the ceramic fuel, the Pu should be lower too, no?

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PostPosted: Mar 03, 2017 9:40 am 
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The Lightbridge fuel is on a 24 month cycle versus an 18 month cycle for each fuel shuffling. So if the fuel assemblies are in for 4 shuffling cycles, that would give the Lightbridge fuel an extra 2 years of irradiation compared to standard fuel assemblies and thus a higher burn-up. At least, that is how I read the linked article.

Jim L.


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PostPosted: Mar 08, 2017 4:58 pm 
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This is an opportunity for nuclear.

The main challenge for nuclear power plants since some years is the collapsed price for natural gas and coal. Thus since about 4 years I regularly read about commercial nuclear plants in the US to become shut down. The solution is to decrease the costs of nuclear power.

An increase of the power of existing nuclear power plants by 20% might decrease the costs of electricity as many costs remains the same doesn`t matter if the plant provides 1100 or 1300 MW.

If the reactor power is increased it requires a higher flow of water thus stronger pumps..it requires larger steam generators...a turbine set that is suitable to take more steam...a bigger generator and transformers...a bigger cooling tower. All in all components > 1 bn $ perhaps 2 bn$.

At the end it could make sense if there is a total refurbishment required for the power plant anyway to uprate it with metallic fuel by 20%.


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PostPosted: Mar 08, 2017 7:56 pm 
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HolgerNarrog wrote:
This is an opportunity for nuclear.

The main challenge for nuclear power plants since some years is the collapsed price for natural gas and coal. Thus since about 4 years I regularly read about commercial nuclear plants in the US to become shut down. The solution is to decrease the costs of nuclear power.

An increase of the power of existing nuclear power plants by 20% might decrease the costs of electricity as many costs remains the same doesn`t matter if the plant provides 1100 or 1300 MW.

If the reactor power is increased it requires a higher flow of water thus stronger pumps..it requires larger steam generators...a turbine set that is suitable to take more steam...a bigger generator and transformers...a bigger cooling tower. All in all components > 1 bn $ perhaps 2 bn$.

At the end it could make sense if there is a total refurbishment required for the power plant anyway to uprate it with metallic fuel by 20%.


Yes, uprating plants has been a sweet spot for the industry for some time. Even simple things like measurement uncertainties in flow rate etc. were an issue with old instruments, so design allowances were included for that. Now, with modern instrumentation being highly accurate, these margins have become obsolete so higher power output can be achieved.

Once you get to larger uprates it gets more and more difficult, things like simple pump scaling laws start to bite and a massive, new pump is required (that doesn't exist so has to be engineered in a FOAK). Still on the whole a pretty sweet deal to a utility if you can get the added capacity at under new-coal-fired plant cost.

What I would like to know is how do they deal with hydrogen threats to containment. Presumably this metal fuel matrix would be zirconium. So how is containment performance in a severe accident dealt with?


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PostPosted: Mar 09, 2017 11:06 am 
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Jim L. wrote:
The Lightbridge fuel is on a 24 month cycle versus an 18 month cycle for each fuel shuffling. So if the fuel assemblies are in for 4 shuffling cycles, that would give the Lightbridge fuel an extra 2 years of irradiation compared to standard fuel assemblies and thus a higher burn-up. At least, that is how I read the linked article.

Jim L.

That can be very useful - in Northern climes - as it means refuelling outages can be timed for the summer every time, when demand is lower.

Any word on when we can see lightbridge fuel elements being deployed?


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PostPosted: Mar 09, 2017 1:27 pm 
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Hi Cyril,

there are a couple further questions on this fuel...

- What is the enrichment of it ..I assume significantly higher than that of ceramic fuel.
- What is the max. power/cm of fuel rod.
- Is Lightbridge doing a spin of of the fuel of military naval reactors
- What alloy is used exactly


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PostPosted: Mar 09, 2017 7:43 pm 
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HolgerNarrog wrote:
Hi Cyril,

there are a couple further questions on this fuel...

- What is the enrichment of it ..I assume significantly higher than that of ceramic fuel.
- What is the max. power/cm of fuel rod.
- Is Lightbridge doing a spin of of the fuel of military naval reactors
- What alloy is used exactly


More questions, no answers! ; )

I guess the enrichment wouldn't be too bad, U/Zr alloys being pretty dense. They are almost certainly using high Zr fraction in the fuel, for various reasons. Hence my question about hydrogen management. I suspect DBA performance of this fuel is much better, and BDBA (SA) performance is worse. LOCA and RIA are probably sweet, but SBO and generally LOHS are probably worse compared to UO2 fuel... that is a lot of hydrogen potential there and a lower melting point fuel...


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PostPosted: Mar 11, 2017 7:07 pm 
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HolgerNarrog wrote:
Hi Cyril,

there are a couple further questions on this fuel...

- What is the enrichment of it ..I assume significantly higher than that of ceramic fuel.
- What is the max. power/cm of fuel rod.
- Is Lightbridge doing a spin of of the fuel of military naval reactors
- What alloy is used exactly
They have 3 types of fuel, each with a slightly different mixture is my guess.

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PostPosted: Mar 12, 2017 7:08 am 
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HolgerNarrog wrote:
there are a couple further questions on this fuel...
- Is Lightbridge doing a spin of of the fuel of military naval reactors
- What alloy is used exactly


This Lightbridge metallic fuel looks like a spin on maritime reactors. As far as I know, the Russian maritime reactors (ice breakers, etc.), such as the KLT-40 reactor, use a U-Zr alloy, although the enrichment is said to be high, in between 30-50%.


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PostPosted: Apr 14, 2017 12:31 pm 
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Is this fuel any better than Thor Energy's fuels that are already under testing ?
Thor Energy says 30% uprates are possible if changes are made at construction time and 15% for uprates.

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PostPosted: Nov 22, 2017 9:09 pm 
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Hi again everyone,

I don't know if the following proposal has been discussed elsewhere (if it has, I can't find it) so I'll outline it here. Let's kick it around a bit.

It invokes RGPU/Thorium burning CANDU reactors utilizing Lightbridge-type metallic fuels.

From what I've been able to gather (see the refs. below) its characteristics/advantages would include:

• Would eventually eliminate nuclear power’s uranium resource limitation (initially its reactors would generate most of their power with in-bred 233U - at equilibrium that fraction would rise to 100%)
• The scenario isn’t so “radical” that the USA’s hyperconservative NE decision makers would be totally unfamiliar with its basics and, therefore, consider it as “risky” as they apparently do anything invoking MSRs
• It represents a much better way for them to “manage” both already separated Pu and raw spent LWR fuel than does MOX-making/burning (converts a much higher fraction of a RGPU fuel loading to fission products (about 90%) & produces much less “new” TRU while doing so1
• CANDU reactors are relatively simple/cheap to make and much more flexible fuel-wise than are “advanced” LWRs -they’re “bigger” but don’t require as much expensive/exotic stuff 2
• Switching to metallic fuel bundles would likely allow them to achieve very high burn ups 3 (~160 GWd/MTHM with 4% RGPU/Th fuel (1)) which would greatly reduce the amount of spent fuel-type “waste” generated/GWe relative to MOX-fueled “advanced” LWRs
• Metallic fuel should be easier/cheaper to reprocess than oxide based fuels (much easier to dissolve – also much better suited to direct “pyroprocessing”)
• It’s also much easier to separate REE-type FP from uranium than from Pu/MA

• "The quantity and radio-toxicity of waste produced from mining thorium ore is two orders of magnitude lower than from the mining of uranium ores”4


1.https://www.researchgate.net/publicatio ... ium_burner
2. https://www.unene.ca/education/candu-textbook
3. http://ltbridge.com/wp-content/uploads/ ... v-15.1.pdf
4. http://www-pub.iaea.org/MTCD/publicatio ... 50_web.pdf (section 5.1)

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