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PostPosted: Nov 22, 2009 2:58 pm 
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DV82XL wrote:
This has been the way it has been reported in the press of late for the results from INL that define it as the amount of uranium-235 remaining over the amount of uranium-235 stated with, expressed as a percentage.....

Actually, the industry has been using this definition for years, along with the regulators.
For instance, LWRs that start with 5%U235 and burn down to 1.2%U235 are said to have a fuel burnup of 76%.
The weirdest thing about this is that it completely ignores the transuranic fissiles created in the process....

One place I came across these figures is in licensing SNF storage facilities -- where typically applicants avoid crediting fuel burnup in criticality safety calcs, as this is a much more difficult case to prove to the regulator than simply assuming fresh fuel ( !!! ).
The reason is that the burnup figures are averages, so one would need to keep track of the exact burnup of each individual fuel assembly -- and be able to prove the tracking system's reliability to the regulator -- along with an accurate way of calculating the amount of transuranics in the fuel....

By contrast, in an MSR, the fuel compositon should be perfectly uniform -- at least until circulation stops & some precipitates start settling out....


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PostPosted: Nov 22, 2009 2:59 pm 
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jaro wrote:
Ida-Russkie wrote:
There is a fifth element which adds to costs that would licensing costs(teaching the NRC). Which may be listed as a sub category to liability. Any research project must get the NRC there learning the ropes.

In this domain, one aspect that regulators pay close attention to is plant decommissioning plans, at the end of plant life.
Without that first fission product containment barrier, we are likely to have far more contaminated material to dispose of....
And, unfortunately, regulators are NOT very impressed by arguments about FP-contaminated waste requiring only a few centuries of decay to become harmless....


Yes but what level of waste. I would assume a bunch of low level waste in the form of concrete. But DOE is performing a lot of D&D work and one could use data from that. One would have to set aside money from the rate payers towards the end of its life cycle. Maybe you would include a glass melter when you build it and process waste was you go. This could also process waste from the D&D activities as well.


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PostPosted: Nov 22, 2009 4:50 pm 
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jaro wrote:
Actually, the industry has been using this definition for years, along with the regulators.
For instance, LWRs that start with 5%U235 and burn down to 1.2%U235 are said to have a fuel burnup of 76%.
The weirdest thing about this is that it completely ignores the transuranic fissiles created in the process....


Which only underlines how useless a value it is. However it should not be called 'burnup' which is properly quoted in megawatt–days per metric ton of uranium metal or its equivalent (MWd/MTU) and means something altogether different.


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PostPosted: Nov 22, 2009 5:28 pm 
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That is then normally defined as %FIMA, the percentage of the initial fissile material. And this is again related to the actual energetic burn-up as there is a conversion value to MWd/tU-235, which is is related to the maximum obtainable energy production of 1tU-235.

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PostPosted: Nov 22, 2009 11:49 pm 
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This sidebar into burnup units notwithstanding, I still don't think this DBI/Century Fuels, Inc. has anything concrete to offer in the way of new or advanced technology, or anything else of interest in the field of nuclear power.


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PostPosted: Nov 23, 2009 6:41 am 
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DV82XL wrote:
This sidebar into burnup units notwithstanding, I still don't think this DBI/Century Fuels, Inc. has anything concrete to offer in the way of new or advanced technology, or anything else of interest in the field of nuclear power.


I have to agree here. They choose the most difficult fast reactor design (gas cooled), which has quite difficult safety characteristics. In addition, it has the highest construction cost of all fast reactor systems.

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PostPosted: Nov 23, 2009 11:48 am 
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Burnup is universally defined based on the initial heaving metal loading, which for uranium is a sum of U-234, U-235 and U-238. Industry uses MWd/tU where U is the total uranium, not just the U-235. At least in the US I have never heard industry use the definition put forth by Jaro. The maximum burnup (based on 200 MeV) is 938 MWd/kgU. LWR burnup is ~50 MWd/kgU or 55/938 = 5.8% on an energy basis. The other definition mentioned is % FIMA, (Fissions per Initial Metal Atom) which is the same thing but on an atom basis rather than an energy basis and includes U-238 in the definition of initial metal atoms.


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PostPosted: Nov 23, 2009 12:17 pm 
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NNadir wrote:

I fully credit what you say on one level, but I don't think that the economic costs of construction are really all that profound, at least if you consider the amortization time of a nuclear plant, which is roughly sixty years, maybe even longer.

....


The better way to look at economic costs of construction is from the perspective of efficient use of capital and resources, particularly since construction costs dominate the total cost of producing nuclear energy. The logic behind moving to a new nuclear power technology that has lower construction costs (LFTR should be around half the cost of SFRs and MHRs, and also less than ALWRs) is similar to the logic of using compact fluorescent light bulbs rather than incandescent bulbs. One gets more benefit from the same investment (or alternatively, one has more left over to invest in other social goods such as education, health care, etc.)


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PostPosted: Nov 23, 2009 9:21 pm 
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Per Peterson wrote:
NNadir wrote:

I fully credit what you say on one level, but I don't think that the economic costs of construction are really all that profound, at least if you consider the amortization time of a nuclear plant, which is roughly sixty years, maybe even longer.

....


The better way to look at economic costs of construction is from the perspective of efficient use of capital and resources, particularly since construction costs dominate the total cost of producing nuclear energy. The logic behind moving to a new nuclear power technology that has lower construction costs (LFTR should be around half the cost of SFRs and MHRs, and also less than ALWRs) is similar to the logic of using compact fluorescent light bulbs rather than incandescent bulbs. One gets more benefit from the same investment (or alternatively, one has more left over to invest in other social goods such as education, health care, etc.)


I fully credit this too. I'm certainly not calling for a static nuclear technology.

I firmly believe that the MSR reactor types should be cheaper, both from an O&M perspective and a construction perspective.

But, to use your analogy, both the compact fluorescent bulb and the LED have higher capital costs than the incandescent. Arguably, the LED is the cheapest over the long run, even though it has the highest capital cost, particularly if one includes external costs, since the compact fluorescent involves the external cost of distributing mercury.

It is generally true that either or both light bulb will save money, but only if one is willing to wait for some period of time to be repaid on the investment.

Once, with a burst that was only half sarcasm, I noted that from a purely environmental standpoint, it is not always wise, at least from an external cost perspective, to buy either kind of light bulb though, public fancy to the contrary not withstanding:

Um, My Compact Fluorescent Bulb Is Hot. (Places and Times NOT to Conserve Electricity.)

Right now the reactors available more or less “off the shelf” are PWR’s. Much as LED’s are superior to CFL’s, it may be a good idea to eventually advance to the MSR (or similar homogenous or quasi-homogenous reactor). But my feeling is that we should be building as many reactors as we can right now. We need not wait until every store is chock full of cheap LED’s to utilize CFL’s.

The perfect should not be the enemy of the good.


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