Construction of new nuclear power plants does not involve stringent requirements for geological disposal

 Regulating safety is a national responsibility, and many States have decided to adopt the IAEA’s standards for use in their national regulations (SSG – 14).

The problem of nuclear waste is covered in Bernard L Cohen, The Nuclear Energy Option, Plenum Press - New York and London (1990). 

Also look up Oklo, natural reactor. You can read there "...One would imagine that engineers working in the nuclear power industry could learn a thing or two from Oklo. And they certainly can, though not necessarily about reactor design. The more important lessons may be about how to handle nuclear waste. Oklo, after all, serves as a good analogue for a long-term geologic repository, which is why scientists have examined in great detail how the various products of fission have migrated away from these natural reactors over time. They have also scrutinized a similar zone of ancient nuclear fission found in exploratory boreholes drilled at a site called Bangombe, located some 35 kilometers away. The Bangombe reactor is of special interest because it was more shallowly buried than those unearthed at the Oklo and Okelobondo mines and thus has had more water moving through it in recent times. In all, the observations boost confidence that many kinds of dangerous nuclear waste can be successfully sequestered underground."

Beside the IAEA Tec Docs there have been done a lot of (lab and field) investigations on the mentioned subjects in the past especially in the US, Sweden, Germany, Belgium and Switzerland. All investigations had been related to the final nuclear waste disposal and the respective performance assessments for the sites. I checked: some reports are still available in the net, for instance from the Sandia National Laboratories (here one example, but there are more: http://prod.sandia.gov/techlib/access-control.cgi/2011/116203.pdf) and from the SKB (the Swedish lab, they have also field experimental sites). Here just one check in their online data base for plutonium: http://www.skb.com/publications/?articleId&title=plutonium&author&publication_search&type=0&language=0&start_year&end_year&orderby=bibas_date&order=desc. The German reports are not available in the net (the sites are Konrad, Morsleben, Gorleben), as well as Switzerland (the site with the perfomance assessment was Wellenberg), and Belgium (the site is Mol).

Dear Sir/Madam,

Thanks for sharing your views.

I think we can have our designs for those things which are under our control.

Nuclear Waste Repository (NWR) is gradually stressed at a particular rate (the rate of stress accumulation on NWR might vary based on several factors) – resulting from imbalances in Tectonic Stresses – occurring at a larger field-scale – which is essentially not under our control.

In other words, any NWR is exposed to “n” number of earthquakes – on a daily basis – off course, at a smaller level (say, less than magnitude 1 or 2 in Richter Scale); when these stresses keep accumulating over a very large period of time (maybe a decade or several decades), it is quite possible that the outer walls of NWR (or for that matter – even - Engineered barriers with metal canisters) might reach a yield point – and in turn – might start developing cracks – and, in turn, - it might end up with the leakage of nuclear waste from the repository {whether geosphere release will reach the biosphere (resulting from the failure of sand-bentonite barrier) or not is yet another issue}. Again, the number and the intensity of earthquakes is not under our control.

In this context, I fail to understand - whether – how come – the Deep Geological Repositories are preferred in order to isolate the (residual) long-lived radionuclides.

And also, I am not aware whether the investigations from Underground Research Laboratories (such as Grimsel and Aspo) have the means to ensure - whether - there exists thermal, mechanical and chemical stability (kind of secular stability /equilibrium)  – that prevents the degradation of canisters in the long run.

It can be recollected that we need to conduct actual field experiments (and not exactly, laboratory-scale studies) in rock in the natural stress environment and before a first release of the stress - as a recompression will not close irreversibly induced micro-fissures – as pointed out by Lars Birgersson and Ivars Neretnieks (1982).

As I understand, uncertainty and risk analysis will definitely help us to get equipped better - in the event of consequences, if any.

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Note:

For example, sixty criticality accidents have occurred in the world since 1945:

38 accidents at reactor facilities and 22 accidents at fuel processing facilities (MacLaughlin et al., 2000).

In addition, in the experimental investigations by Levchuk et al. (2009), they have found that plutonium isotope’s plume in the aquifer traversed about 10 m downstream of the radio-nuclides source, and further showed that all plutonium in the aquifer originated from the trench associated with the very near-surface disposal.

Recently, Novikov et al. (2011) have shown that radio-nuclides have penetrated to depths of up to 50 cm in 50 years in an undisturbed soil layer.

Further, from geological perspective, the suitable host being crystalline hard rock such as granite, which contains fractures that exist either due to natural conditions or resulting from repository construction activities, and such fractures could potentially form pathways for eventual radio-nuclide release to the biosphere (Silveira and Alvim, 2011).

Reference:

ISH Journal of Hydraulic Engineering, 2015, Vol. 21, No. 2, 162–176

http://dx.doi.org/10.1080/09715010.2014.984249

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Thanks for your time.

Suresh Kumar.

http://www.doe.iitm.ac.in/gskumar/

Dear Suresh,

regarding the issue of deep repository site: in the end of the day, this is a political decision. It depends from the fact if the nuclear waste shall be recoverable or not. In Germany this decision is not taken yet. Regarding the geological setting our government restarted from zero the discussion of the type of host rock after Fukushima. Before was the decision that we will have the final nuclear disposal site in salt rock. Other countries would like to have a repository in salt rock, but they do not have this geological formation. Sweden only has granite, Belgium has clay. For the moment Germany is constructing a repository in a former iron mine (shaft Konrad), which will be allocated for low level waste. In parallel was even started a discussion about potential disposal in deep drillings with the scope to spread the risk and to keep the waste recoverable. In our performance assessments the repository must be safe for 1 million years. Even we had passed 30 years of extensive nuclear disposal research we are more or less back to the beginning. The problem is not solved.

Also the testing methods are not appropiate, infact they can not be. Here was developed a method for the permeability measurement based on in-situ gas migration tests. Of course is not possible to find exact solutions in the lab, but the question is: how to do reliable experiments in low permeable rock and to receive reliable results in a manageable period ?

I did several projects in the basic evaluation of potential nuclear repository sites and I was involved in a lot of uranium mining remediation activities (as uranium is used to produce the nuclear fuel sticks) and my personal opinion is that nuclear power should not be used, because the environmental risk and damage of the whole production and waste disposal chain is not manageable in practice. 30 years of research didn't change anything in this conclusion.

Best regards,

Petra

Thanks Dr. Petra for sharing your views.

Yes………..it happens to be a political decision at the end of the day…………

And, I completely agree with your views……

But, keeping aside, the political aspects,

let me try to focus on the field-scale hydro-geology........

Well, salt rock is a better option as it is “generally” believed that it is not associated with the mobile fluid; and, it is assumed to be nearly impermeable (that is, we assume that the salt rock is characterized by zero permeability); and above all, it is supposed to be stable geologically.

But, we should also remember that the salt rock exhibits “plasticity” as you know.

That is, it might form – a kind of pore network – under a tiny deformation – and, as a result of which – it will form a network of connected pathways – for the effective fluid mobility – and in turn, the salt rock might develop a significant permeability (off course, how significant, we do not know OR it might at least act as a Leaky Aquifer) - which is against the principle of – what is believed widely – as on date. In turn, this will significantly influence the resulting radiation dose rate, in the event of consequences, if any.

In addition, old mines are susceptible to salt dissolution. On the other hand, containers are susceptible to corrosion and/or damages in the long run.

In essence, we do not have control over – (a) the physics – that is, the exact external and internal pressures that will be acting on / over / sides of the salt rock – over a period of interest; (b) the chemistry – that is, the type of chemical reactions – that might be occurring between the salt rock and the surrounding connate water; and finally (b) the mathematics – that is, the water in the vicinity of salt rock – is somehow – waiting to attack the rock and eventually find its way within the salt rock by some complex mathematics………..and the story goes on……………..

Thanks again for sharing your practical experiences and enlightening me.

Suresh Kumar.

Heat from buried waste mobilizes groundwaters, initiating convective overturn that destroys site integrity.  I was with State of Nevada Yucca Mountain Project University of Nevada, Reno Nevada found burial ruinous.  .

Article Closing yucca mountain: Litigation associated with attempts ...

There is no such thing as a dry rock.  Surfaces of minerals coat with fluids.  Fluids range from vanishingly small in salt domes to significant near surface.  Heated sediments on descending plates sweat out soluble matter.  Dickson and Hsu 2000 paper in Vol. 29, p. 103-109 J Geodynamics describe mechanisms.

Dickson, F. W. and Hsu, K. H., 2000, Disequilibrium reactions in Earth's gravitational field, J. Geodynamics, v. 29, p. 103-109.