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PostPosted: Nov 30, 2014 2:52 am 
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Kurt Sellner wrote:
macpacheco wrote:
The NRC is already fully paranoid in nuclear safety matters.


I agree. The NRC is so afraid of something going wrong that they don't want to try anything new. This status quo means that nothing "unsafe" can be done, or that any current policy or practice that can be proven unsafe will be ended.

I think you got it backwards. The NRC doesn't need to prove something is unsafe. The nuclear operator must prove it is safe to the NRC satisfaction. The NRC is free to increase the demanded level of safety without proof those demands are likely to actually increase safety.

Essentially the NRC did a lot of good pre TMI. Between TMI and Chernobyl it did half good and half bad. After Chernobyl it went nuts and most of what extra it demanded wasn't helpful at all. Its the result of the NRC having total freedom to do whatever it wants to provide a perception that its increasing safety.

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PostPosted: Dec 01, 2014 11:57 pm 
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Tomswift wrote:
Waiting for higher isotopes to decay is not a practical way to get your bomb grade Plutonium.


Not for a person it won't, but for a species it would. What I'm saying is that the ban on reprocessing of spent nuclear fuel out of a concern for deterring weapons production just means that some future generation can dig up what would become weapon grade plutonium.

The only means we currently have to destroy this material is a nuclear reactor. By not destroying it now means that we are leaving weapons grade plutonium for some future generation to exploit.

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PostPosted: Dec 02, 2014 12:57 am 
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macpacheco wrote:
I think you got it backwards. The NRC doesn't need to prove something is unsafe. The nuclear operator must prove it is safe to the NRC satisfaction.


How does the NRC determine a reactors safety currently? They have a checklist. A checklist that has not changed since 1985. When approving a new reactor thy will run down their list.
- Containment dome? Check.
- Control rods? Check.
- Backup generators? Check.
- Freaking huge water supply? Check.
- Primary cooling? Check.
- Secondary cooling? Check.
- Tertiary cooling? Check.
- Hydrogen gas recombiners? Check.
- Emergency ventilation for hydrogen gasses? Check.

I've seen it several times now in presentations on MSRs, the presenter will talk about how the design has control rods only because it makes the NRC happy. It's just cheaper and easier to spend the time in engineering in control rods than it is to spend the time convincing the NRC on how they aren't needed to make it safe.

The NRC only knows solid fueled, uranium cycle, water cooled fission reactors. Give them anything else and they don't know what to do. That's been the complaint for a very long time. Because that is only what the NRC knows we are still putting three inherently incompatible things in the same place, heat, zirconium metal, and water. Not only are those three incompatible things in the same place, thanks to the NRC, we put them in the same container as enriched uranium and its fission products.

If the NRC wasn't so hung up on things like water cooling and control rods we might have seen some much safer nuclear reactors built already. I don't just mean MSRs. All kinds of reactor types are potentially much safer than what we have now. Gas core reactors. Aqueous reactors. Air cooled reactors. But we've seen none of them because the NRC has it's check list.

The NRC is preoccupied with 1985...
http://www.youtube.com/watch?v=K38xNqZvBJI

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PostPosted: Dec 02, 2014 3:16 am 
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If only the NRC only used checklists, then it’d be a fast and easy licensing process. Just take the regulator checklist and design those components in. Easy peasy.

I think the problem is much more tenacious. The NRC can ask endless complicated computer analysis of all kinds of accidents and scenarios, then take endless amounts of time to review them, and just when they decide, after many cycles of asking more and more questions that the analysis getting so detailed that it raises more questions than it answers…. And then at the end of of it all they “surprisingly” find a big error in the finite element mesh modelling and you’re back to square one…. you get the point. In stead of working together with a clear purpose in mind, the NRC and applicants simply dartle around each other and making everything more complicated than it needs to be. This is a lesson in how not to improve safety and how not to prioritize and how not to set up an effective licensing framework. The NRC is paid to analyse and naturally thinks this is its mission. To analyse and charge the hours to the applicant. Not to give off licenses. If the NRC gives off a license they stop getting money.

Checklists work quite well. The Utility Requirements documents for example are basically checklists, albeit very elaborate. This works better than endless analysis or endlessly referring to nested codes and standards and then make a fuss if a component is even slightly off from the standards. Regulators that delve into endless detail or rigidly cling on to thousands of codes and norms don’t do well. Regulators that zoom out and put the end responsibility on the applicant, where it should be in my opinion, do well. This is where the NRC should be going in my opinion.


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PostPosted: Dec 04, 2014 11:37 am 
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In case this wasn't referenced:

http://www.nrc.gov/reading-rm/doc-collections/cfr/part073/part073-0055.html

Early on in the discussion transformers and power lines were mentioned. A large chain could be rigged to fault offsite power sources by being slung over the transmission lines. Reliance on the diesels would then be a necessary condition.


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PostPosted: Dec 05, 2014 3:13 am 
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Kurt Sellner wrote:
Not for a person it won't, but for a species it would. What I'm saying is that the ban on reprocessing of spent nuclear fuel out of a concern for deterring weapons production just means that some future generation can dig up what would become weapon grade plutonium.
To reduce the Pu 240 content of SNF to the levels needed to build a fission bomb would take several half lives. Even one half life is over 6,500 years, so worrying about what problems we would have with people wanting to do bad things with the then purer Pu 239 would be like a King in 3,000 BC worrying how he can keep the secrets of the production of bronze swords from his peoples enemies in AD 2014.

I don’t try and predict what society will be doing more than about one hundred years in the future, and even that is pushing it.

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PostPosted: Dec 05, 2014 7:40 am 
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Tomswift wrote:
Kurt Sellner wrote:
Not for a person it won't, but for a species it would. What I'm saying is that the ban on reprocessing of spent nuclear fuel out of a concern for deterring weapons production just means that some future generation can dig up what would become weapon grade plutonium.
To reduce the Pu 240 content of SNF to the levels needed to build a fission bomb would take several half lives. Even one half life is over 6,500 years, so worrying about what problems we would have with people wanting to do bad things with the then purer Pu 239 would be like a King in 3,000 BC worrying how he can keep the secrets of the production of bronze swords from his peoples enemies in AD 2014.

I don’t try and predict what society will be doing more than about one hundred years in the future, and even that is pushing it.


But in reality, repositories like Yucca Mountain have to prove that there won't be even a slight fraction of background radiation increase for 100,000+ years.

Both this long lived waste and long lived proliferation argument are silly at heart. Terrorist attack on a facility with fresh fission products isn't, its something to take seriously. This is where the risks of the nuclear fuel cycle really are, when things go badly with fresh fission products.


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PostPosted: Dec 06, 2014 6:08 pm 
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I agree the long lived waste problem is a red herring used by anti-nucs as a road block against nuclear power. For much the same reason LFTR must be made non viable, because it would remove the long lived waste road block. Arguments such as “corrosion” problems, unobtainium needed, it will take 20 years to develop, or someone could make bombs from its fuel are all used to delay development, and implementation.

As far as terrorist attacks on NPPs, they have a hard nut to crack. The easiest place to attack would be the spent fuel pool, but this is not easy to get into with a large enough charge of explosives to spread much material around.

Now a state sponsored attack with a few 2000 lb bunker busters on the SNF storage pools, that would do major harm.

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PostPosted: Dec 06, 2014 7:23 pm 
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Cyril R wrote:
Tomswift wrote:
Kurt Sellner wrote:
Not for a person it won't, but for a species it would. What I'm saying is that the ban on reprocessing of spent nuclear fuel out of a concern for deterring weapons production just means that some future generation can dig up what would become weapon grade plutonium.
To reduce the Pu 240 content of SNF to the levels needed to build a fission bomb would take several half lives. Even one half life is over 6,500 years, so worrying about what problems we would have with people wanting to do bad things with the then purer Pu 239 would be like a King in 3,000 BC worrying how he can keep the secrets of the production of bronze swords from his peoples enemies in AD 2014.

I don’t try and predict what society will be doing more than about one hundred years in the future, and even that is pushing it.


But in reality, repositories like Yucca Mountain have to prove that there won't be even a slight fraction of background radiation increase for 100,000+ years.

Both this long lived waste and long lived proliferation argument are silly at heart. Terrorist attack on a facility with fresh fission products isn't, its something to take seriously. This is where the risks of the nuclear fuel cycle really are, when things go badly with fresh fission products.

The more I think about yucca, the more I reach the conclusion we should leave SNF at the reactor site and use Yucca money to have one big fuel reprocessing facility. Perhaps let fuel cool for 30 years before moving to the reprocessing site (lower radioactivity), and initially wait 60 years to allow enough $$$ to be pooled up to pay for the reprocessing site. Focus on scale and costs. The problem with reprocessing in the USA is the old adage privatize profit, socialize loss. If we had a society that didn't reject nuclear power, we could easily justify paying the extra costs to reprocess, like they do in UK, France, Japan and Russia (plus those countries that want to reprocess but that can't because they're stuck with contract with the USA that prevents them).

Even better. Reprocess fuel using pyro reprocessing, add some plutonium and startup DMSRs with that. Perhaps even have a large DMSR reactor site fairly close to the reprocessing plant.

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PostPosted: Dec 09, 2014 2:43 am 
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Cyril R wrote:
If only the NRC only used checklists, then it’d be a fast and easy licensing process. Just take the regulator checklist and design those components in. Easy peasy.

I think the problem is much more tenacious. <snip>


Yes, I agree that the process is more than just a checklist. It's more like checklists nested upon checklists. My point is that the NRC is not equipped to license anything too far from the norm of what they licensed in the past. The NRC is also insufficiently motivated to care about licensing anything other than what they've licensed before.

My other point is that the NRC appears to have a rather backwards approach to deterring terror attacks on nuclear sites. They seem focused on building higher and thicker walls to keep the terrorists out than where I believe they should place their focus, on destroying the material so that they have nothing to steal.

I remember reading about neutron destruction of nuclear waste a very long time ago. This is not something new. I've also seen many point out on this forum that neutrons are very expensive and should not be spent lightly. There should be some happy medium here. Can't we spend some of our neutrons on destroying radioactive waste and still have enough to produce the energy we need?

Perhaps it's my cynicism but I have to wonder about the logic behind some of the NRC policies as well as the DOE. It seems like if they are protecting their existence more than anything else. If they actually start to license reactors then the problems of nuclear waste, energy shortages, and so on might actually be solved. Then what will they do?

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PostPosted: Dec 10, 2014 9:31 am 
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Fissile material theft isn't a major concern at all. It is more to do with the inherent risks of fresh fission products, and you can't destroy those. Any facility that has large amounts of fresh fission products needs extensive physical barriers, in my opinion. With LWRs having concrete containments, the thickness needed to hold pressure with reinforced concrete is so large already, you get the physical protection sort of "for free". And inside the containment we have the biological shield to protect workers and non nuclear equipment in the plant. The thickness needed again is so large, you get more "free" physical protection versus missiles and the like. MSRs also should have thick concrete or similar shields. If we are allowed to have the biological shield as our events shield, then the building over that can be a lightweight steel building for example - resistant to high winds and storms but not missiles. This should be a cheap and compact way to make a nuclear plant.


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PostPosted: Dec 11, 2014 7:58 pm 
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Kurt Sellner wrote:
I remember reading about neutron destruction of nuclear waste a very long time ago. This is not something new. I've also seen many point out on this forum that neutrons are very expensive and should not be spent lightly. There should be some happy medium here. Can't we spend some of our neutrons on destroying radioactive waste and still have enough to produce the energy we need?

Using neutrons to transmute radioactive fission products is worthless and very expensive.
First you would need to separate the waste by elements.

Any element with a significant fraction of its isotopes that will become radioactive when it gets an extra neutron is automatically ruled out. Not only would you spend enormous amounts of money on the neutrons but you may actually increase the radioactive waste problem.
Any element that has only short lived fission products is best simply left alone and given a bit of time to settle down.
Finally any element with high yield will require too many resources (at least until fusion becomes commonplace) and should not be considered.

By this time you are down to about one fission product to consider, iodine. But iodine's radioactivity is so low that you almost can't get sick from it even if all the iodine you take in is from a reactor.

So, no transmutation using neutrons is not something to entertain at all.


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