As you may know, there is a big debate on whether SMRs will create more nuclear waste. Citizendium's Debate Guide on Nuclear Waste Management features a report from the National Academy of Sciences claiming that the waste volume will increase by "factors of 2 to 30".
Jack's rebuttal was excellent, but now the anti-nukers at skeptical science dot com are claiming what NAS really meant was not the waste from spent fuel, but the irradiated steel. That was not at all clear in my brief reading of the report. I have added a section on this issue to the Debate Page, but I think it could use a better response. Can't all this steel be recycled for new reactors? Why should any of it go to a landfill?
The problem is Cobalt-60. If there is any natural cobalt (Cobalt-59) in reactor vessel steel, it can absorb a neutron and become Co-60. Nickel ores usually contain some cobalt. Steels that use nickel as an alloy will contain some cobalt. Co-60 emits two rather nasty photons (1.2 and 1.3 MeV) when it decays.
As always with radiation, you have to do the numbers. You get the numbers down two ways.
a) Low Cobalt content. Stainless steels are now available with max cobalt content of 0.05%.
b) Time. The half-life of Co-59 is 5.3 years. In 53 years, 99.9% of the Co-59 is gone.
When you do the numbers, you may find that you need to store some steel for at most a few score years before it can be contact handled. But that assumes a rational world.
It would be nice if we could get some numbers, and say definitively that the steel from these reactors is NOT the big problem NAS is claiming. The best I can find is from a World Nuclear Association discussion of recycling decommissioned steam generators:
"each 12m long and 2.5m diameter, with mass 100 tonnes, and contained some 4g of radionuclides with about 340 GBq of activity. Exposure was 0.08 mSv/hr at one metre."
The NAS report has no numbers like this, perhaps because they don't want to reveal the triviality of their claim, or perhaps I am missing something. I know that segmentation of decommissioned reactors is done under water. Is the steel from a reactor core much more radioactive than a steam generator? Is it so bad that recycling to make new reactors would be a problem?
David, the steel they are talking about is the steel of the Reactor Pressure Vessel, core supporting steel, etc. The "core" itself is just the removable fuel assemblies which contain very little steel. After the core fuel assemblies are removed (and handled differently), what steel remains is the discussion.
By "they" I assume you mean the authors of the NAS report. The quotes are from the abstract of that report.
Most people will read this report as I did, and assume they are talking about the fuel waste. So we decided to leave Jack's rebuttal as is, and treat the non-fuel waste as a separate issue.
Wow. I didn't know the "cleanup" was still going on - and at such a huge cost, and unnecessarily. The little bit that leaks into the river will be even less significant as it is diluted by millions of gallons of water. When my wife and I took a guided raft trip down the Colorado, we were told to pee in the river. I thought that was kind of gross, but the licensed guide said "Dilution is the Solution to Pollution".
As you may know, there is a big debate on whether SMRs will create more nuclear waste. Citizendium's Debate Guide on Nuclear Waste Management features a report from the National Academy of Sciences claiming that the waste volume will increase by "factors of 2 to 30".
https://citizendium.org/wiki/Nuclear_waste_management/Debate_Guide#Increased_waste_from_Small_Modular_Reactors
Jack's rebuttal was excellent, but now the anti-nukers at skeptical science dot com are claiming what NAS really meant was not the waste from spent fuel, but the irradiated steel. That was not at all clear in my brief reading of the report. I have added a section on this issue to the Debate Page, but I think it could use a better response. Can't all this steel be recycled for new reactors? Why should any of it go to a landfill?
https://citizendium.org/wiki/Nuclear_waste_management/Debate_Guide#Non-fuel_waste
Maybe someone in the choir can write a better rebuttal, if Jack doesnn't have time.
David,
The problem is Cobalt-60. If there is any natural cobalt (Cobalt-59) in reactor vessel steel, it can absorb a neutron and become Co-60. Nickel ores usually contain some cobalt. Steels that use nickel as an alloy will contain some cobalt. Co-60 emits two rather nasty photons (1.2 and 1.3 MeV) when it decays.
As always with radiation, you have to do the numbers. You get the numbers down two ways.
a) Low Cobalt content. Stainless steels are now available with max cobalt content of 0.05%.
b) Time. The half-life of Co-59 is 5.3 years. In 53 years, 99.9% of the Co-59 is gone.
When you do the numbers, you may find that you need to store some steel for at most a few score years before it can be contact handled. But that assumes a rational world.
It would be nice if we could get some numbers, and say definitively that the steel from these reactors is NOT the big problem NAS is claiming. The best I can find is from a World Nuclear Association discussion of recycling decommissioned steam generators:
"each 12m long and 2.5m diameter, with mass 100 tonnes, and contained some 4g of radionuclides with about 340 GBq of activity. Exposure was 0.08 mSv/hr at one metre."
The NAS report has no numbers like this, perhaps because they don't want to reveal the triviality of their claim, or perhaps I am missing something. I know that segmentation of decommissioned reactors is done under water. Is the steel from a reactor core much more radioactive than a steam generator? Is it so bad that recycling to make new reactors would be a problem?
There are two aspects to this problem:
1) Computing the dose rates near the activated steel
and how it decays thru time.
2) Calculating the harm associated with those dose rates.
1) Is a straightforward exercise for a good modeler
who has access to a good reactor physics code such as Serpent.
But you are still asking for a multi-man week effort for each design.
2) The harm depends on your radiation harm model.
If it's LNT, then any damage is never repaired, the harm just builds up,
so we adopt ALARA, bury the material regardless of the dose rates.
If youre an LNTer, you can ignore the results of (1)
and just say the steel is radioactive.
Not sure what you mean by reactor segmenation.
There is very little steel in conventional fuel assemblies.
The metal is almost all zirconium which does not activate
altho the impurities in the Zr can.
David, the steel they are talking about is the steel of the Reactor Pressure Vessel, core supporting steel, etc. The "core" itself is just the removable fuel assemblies which contain very little steel. After the core fuel assemblies are removed (and handled differently), what steel remains is the discussion.
By "they" I assume you mean the authors of the NAS report. The quotes are from the abstract of that report.
Most people will read this report as I did, and assume they are talking about the fuel waste. So we decided to leave Jack's rebuttal as is, and treat the non-fuel waste as a separate issue.
https://citizendium.org/wiki/Nuclear_waste_management/Debate_Guide
By the way, speaking of Hanford, what was the story on that closure? I seem to remember something about leakage into the Columbia River drainage.
Al,
It 's a massive, half trillion dollar ripoff of the taxpayer. Pls check out
https://gordianknotbook.com/download/you-want-nuclear-waste-ill-show-you-nuclear-waste
The nuclear establishment depends on these boondoggles which depend on keeping the public petrified of radiation. Hence their support of LNT.
Wow. I didn't know the "cleanup" was still going on - and at such a huge cost, and unnecessarily. The little bit that leaks into the river will be even less significant as it is diluted by millions of gallons of water. When my wife and I took a guided raft trip down the Colorado, we were told to pee in the river. I thought that was kind of gross, but the licensed guide said "Dilution is the Solution to Pollution".