As far as granite-hosted final waste disposals are concerned, current requirements are a long-term safety of approx.. 1 million years which is reasoned by the half-life period of plutonium isotopes and the granite´s apical part being located at a depth a greater than 300 m under ground with a good sealing capacity of the non-granitic roof rocks above.

The granite is the natural source rock of uranium (background appr. 4 ppm U) with hot granites reaching a level of 20 ppm U. Moreover, a lot of U-vein-types and low-grade large tonnage deposits (e.g., Namibia) are hosted by magmatic rocks of the granite suite.

I studied for more than 6 years mainly the Variscan U deposits in Europe which formed around 300 Ma ago, and underwent supergene alteration during a period of time of less than 60 Ma. During that time strong fracturing on a regional scale was overprinting the country rock around, its wall rocks and the granite themselves which display a characteristic joint pattern. There were also mantle plumes sparking basic and alkaline volcanic rocks in the period of time younger than 60 Ma. Neither the structural, nor the temperature events have affected the U-bearing granites and their U deposits. This can be proved by a meticulous U/Pb age dating, paleogeographic and terrain analyses during the recent past including the study of the U/Pb equilibrium (< 0.8 Ma).

On the other hand, there are also self-sealing capacities to be observed in the granites caused by nontronite (smectite group clay mineral) and kaolinite-group phyllosilicates) which developed along with post-granitic hydrothermal processes and per descensum supergene alteration. The immigration of meteoric and hypogene fluids is hampered despite of the strong fracturing to be observed especially in shallow granites.

By and large, where mother nature has accumulated and preserved uranium for more than 300 Ma , human beings should not try and create by hair-splitting arguments a dangerous setting which does not exist. There is no doubt that radon and radiation is harmful to men but taking into account the three important issues: Time, distance and thickness may minimize the risk of causing radiation-induced diseases.

HGD

The United States Department of Energy studied the final nuclear waste disposal problem in the 1980s. Yucca Mountain was selected by Congress from the five sites being considered, and research stopped; but as I recall, Nevada never agreed and I lost track of the issue. You might check the literature of the time.

Yes...the main issue is infiltration, monitoring and modelling.

They are relatively controllable issues. The nice thing about radioactivity is that it can be observed easily at ridiculously low level. Heavy metals? Organophosphates...they are hard to observe and control because they are not radioactive.

Half the toxic waste disposal issues (and those associated with radioactive wastes) have to do with the feared "bathtub" effect...meaning the waste disposal facility cover in a conventional landfill will eventually erode become exposed, crack and go from convex to concave, it will then theoretically leak water via infiltration into the waste and the water so introduced will have nowhere to go. Under this scenario the water will trickle in and never trickle out. Liner systems nowadays are designed with many redundant layers of plastic and clay and they are generally kept dry as long as the water all drains to the sump pumps. So...the theory of perpetual care is that everything fails and over time the lower liner system will contain so much water that it becomes a saturated mass and will eventually seep outward. The answer is to make sure there is an "inward gradient". Now...with the amount of heat made by waste nuclear material it might be tricky to make sure the system does not circulate water and that the system stays static and hopefully dry enough to minimize not only convective flow but diffusive flow.

In a granite system...just make sure it's cap is convex. Don't build it underwater....or at least not where there is an offsite gradient. Pick a stagnant hydrogeological area.

Perhaps the most unique issue for radiogenic wastes...Radioactive waste heat can be calculated and the heat capacity of the enclosing granite can be estimated to absorb enough heat to minimize any sort of thermal gradient buildup during the heating life that might lead to convective/diffusive flow in "tight" rock down any kind of chemical/thermal/hydrostatic gradient. Rock has a very high heat capacity and granite is relatively "tight". It would take a relatively high hydraulic gradient to drive fluid through it

It is not that hard to make sure the so called granite cap in the case of a nuclear waste repository is and remains convex upward...and that there are no duckponds. I worked with nuclear substances in mining exploration long enough to get a handle on fluid migration and with conventionally toxic substances for 25 years with the USEPA and constantly was amazed that nuclear waste had a theoretical 10,000 year design life but the PCB landfills I worked with never had anything more than a 100 year design life. A lot of thought can go into a 10,000 year design life. I tried to use a 10,000 year design life because I thought it was easy to accomplish with non oxidizing wastes such as PCBs, plasticizers that actually "healed" the natural tendency of plastics to stiffen and crystallize upon exposure to UV etc.

Regarding granites...it is a natural fit. Just look at the granite and see if the quartz is "smokey". Smokey quartz has undergone radiation damage. Heat it and the damage goes away. So...would heating of a granite by radioactive waste tend to do the same thing as a PCB plasticizer to a high density polyethylene sheet? Probably...but as with HDPE membranes and PCB's there is no such consideration and believe me...it was a verboten topic.

There are many kinds of granite some of which are silicified and are really water tight. It is relatively easy to test for water tightness or gas permeability etc. by simply drilling a hole and seeing if it is sufficiently dry and gas tight by determining the age of the water or gas within. If the water is super old...say 1,000,000 years the first consideration of the 10,000 year design life is likely to be met. The hydrogeology involved is not really all that hard to consider. There are, for example, many petroleum traps in the world that do not leak much....in fact they even contain natural gas and or helium gas for long periods.

I have heard lots of so called hydrogeologists claim there is no such thing as impermeable. Not so. Geological impermeability is a relative thing and there are many places where the ground is "dry" and free from infiltration under long term natural head conditions. I worked with one naturally pressurized aquifer in central illinois, the Mahomet, that had "old" water within it. Many studies by the USGS and other reputable agencies showed the overlying caprock was "tight" and could support a strong artesian gradient. However, those studies were ignored by the powers that controlled decision-making, likely because nobody trusts or even understands hydrogeology/hydrogeochemistry/isotope sysytematics etc. To save the huge sandy water reservoir withing its natural containment system, likely somebody recommended putting toxic waste landfills in "thin" glacial substrates overlying some kind of lime/dolomite/pseudokarstic area where leaks are virtually impossible to remedy...think Hanford Nuclear Waste isolation facility.

The Bathtub fear apparently won. Hydrostatics did not...and that was just from a relatively benign "toxic" constituent, polychlorinated biphenyl...that was hydrophobic and was not mobile in soils by any stretch of the imagination because of the presence of natural organic material.

Radionuclides? They can be contained but I fear nobody will believe it....even PCB's were considered too risky. Is the comparison meaningful?

NIMBY (Peter Sandman column) (psandman.com). I worked with the same agency in EPA and found this work provocative. The upshot...it's not the geology stupid.

It does seem nuts to insist that repositories are too dangerous and to insist on keeping radioactive materials in surficial temporary storage. One stupid cruise missile...and Oh what a mess. Do not keep the waste above ground. There is "tombstone" rock to be had and there are areas where groundwater flow is either negligible or non-existent.

Everyone knows perhaps one of the most famous examples of such relatively water tight material...sugarloaf in Rio, El Capitan in Yosemite. No do not put it there...just find one plug of nice uncracked rock...and granite is one of the more chemically resistant rocks. Other rock...gabbro, diorite, dunite....they do not tend to form such natural features that stick out above the countryside for 10,000 years or more....

There are many granites that have lots of natural radioactive materials that can be studied in fancy ways to determine if radon or helium escape despite being relatively radioactive in the overall scheme of things.

I indeed studied the Nevada disposal facility a bit and was truly horrified to find the whole issue of its denial seemed to hinge on the possiblity of there being a natural radioactive spring in "death valley" somewhere thousands of years in the future. The spring of concern was something like 125 miles away if I recall. 125 mile plume trails are very hard to consider real. I did it though...while chasing water soluble uraniferous material seeping out of a hot granite north of South Park all the way to a mine at the other end of South Park. That flow was entirely uncontrolled and subject to free flow and snow pack infiltration all along the way. It eventually accumulated in carbon trash at the far end of the park where it was removed...more or less.

While there were undoubtably more things at play that caused decisionmakers to end the PCB project discussed above, there is an interesting comparison. For example, there are radioactive hot springs in populated areas of Colorado that I know of personally. It was in Idaho Springs or nearby and it was considered a "spa". A health Spa! Maybe not so popular now but still, it was "Radium Hot Springs". That was its name. Indeed there are radioactive seeps all over. I encountered many myself as an exploration geologist..one of which was near Pikes Peak....it was full of fluorescent and radioactive water soluble minerals...such as Schrockingerite...and it pegged my scintillometer. Hot...but it would not fog my badge...I tried to fog it. Nope. Nobody seemed concerned at all and most likely those areas are still open.

So...it seems once the media focusses on something like the Nuclear Waste hydrology that isn't somehow perfect there is no real way to erase it. That spring I found actually seeped through South Park and popped to the surface near Hartsel where radium was once again at the surface. Nobody was panicky and likely the public health service knows about it by now...40 years later. I know because I drilled some of it...as a radium anomaly upstream of a known uranium mine active at the time...Tallahassee Creek.

Here I attach a small report done to monitor groundwater. It is a mere example of what can be done. The perfect is not the enemy of the good.

The blue bubbles are azurite stain bubbles. They indicate the granite was impermeable to what was probably gaseous copper carbonate. The rock is very impermeable...so much so that gas bubbles got stuck and became gas bubble fossils.

Steve Johnson got right into the problem. His take-home - do not leave the radioactive waste on the surface. It has to go underground. Also there are granites and granites. Some granites are fractured and allow water to circulate. Before any underground reservoir is constructed there must be a groundwater hydrology study. And finally - storage of radioactive waste is a task for the next 10,000 to 1 million years. How long has our civilisation existed? How long will it exist? Is the creation of this waste a very irresponsible act?

You may find some useful literature in searches on the Vaalputs low level nuclear waste site in Namaqualand, South Africa. Studies on the low level waste site which is hosted in calcrete focussed on the extremely low rate of historical erosion in the area as indicated by remnant ca. 100 Ma volcanic cones nearby, combined with arid conditions and studies which suggested that much of the groundwater was fossil with limited recharge.

When gneiss is heated it does not break, because it formed under high temperature/pressure conditions. On the other hand when granite is heated it breaks up, because it formed under lower T and P conditions.

The Pomaki people in Northern Greece (ancient tribe who provided the archers in the expedition of Alexander the Great) use slabs of gneiss to cook their bread in outside ovens today.

Therefore, gneiss would be preferable place to store nuclear waste.

The question “Is granite suitable for High-Level Waste Disposal Facility?“ I would reply with a clear „No!“ Why? Natural uranium is distributed more or less, for example, in granite at the ppm level. Of course, there are some rare exceptions. However, nobody knows precisely the behavior of vast amounts of high active fission products in any deposit. Noteworthy is also the amount of high nuclear waste. That is at the moment 380000 t, which increases by 10000 t per year. What happens in a container over million years? Do not forget that the half-life time for U-238 is 4.46 billion years. Also, this stuff must be safely deposited.

What has happened in the last 1000000 years? How safe are all long-time forecasts? No scientist in this world can give a clear and indisputable answer!

Can you answer the question: In which manner change the temperature in such a container with high-level waste? That is a significant difference from the uranium in a natural deposit.

What happens if the temperature of the container increase? At which temperature start the water movement in the granite – mowing to the hot container?

Dear Shoaib

I suggest to review literature first on the possible solution to your problem.

Regards

Ijaz

Lots of studies available from Finns and Swedes who have underground laboratories in rocks not unlike those of Namaqualand. Finns may soon start disposing... in gneiss ...under the sea!!

BTW: the low level radioactive waste that arrives to Vaalputs is NOT disposed in calcrete but in the clay bearing sediments of the Vaalputs Formation. Calcrete occurs as near surface duricrust or impregnations in the regolith (weathered Vaalputs Formation).

My answer is simple: no!

All those who want to know more about the response of nuclear waste and fission products to natural processes in a hydrological system should have a look to the uranium deposits at Mounana in the Haut-Ogooué Province of Gabon where 15 natural reactors were active 2 billion years ago. They are hosted in a claystone-sandstone sequence but the natural processes leading to a modification of the isotope ratios as well as the hydrothermal temperature regime can be studied there. A direct transfer to the remaining contenders salt and clay among the potential host rocks for a final waste disposal should be done with caution. We used during U exploration the so-called Oklo Effect to characterize the impact of hydraulic systems on high-grade uranium ore deposits such as the unconformity-related deposits in Canada and Australia which come close to final waste deposits.

Why do we sideline this natural reactor and its fission products ?

HGD

Ah, the 1950s... crazy times.... we bought a mineral water in Torino that came at a premium because it was ... radioactive! The label had a picture of a miner digging for uRANIUM..

granites are not the only hot crystalline rocks with uranium: once I found a mountain in Namaqualand made of of charnockitic granulite with up to 50 ppm uranium and 400 ppm thorium... and the same region sheep grazed in days of old at the foot of a dyke of monazite with 10 percent thorium and uranium along with it...

MA

My answer is yes...do not leave it above ground in relatively insecure storage. Next thing you know some nut is going to aim a conventional missile at the storage area and use it as hostage.

Who might that be? Where would that ever happen?

I think there is way too much concern about nuclear waste storage, especially now that fossil fuels are supposedly leading us to oblivion. I spent 25 years or so trying to dispose of PCB waste and the main problem was that decisionmaking had to be made by relatively uninformed administrators. Nowadays decisionmaking is never allowed because the administrators still plea they are uninformed.

Is it true...wisdom is finite but stupidity isn't?

PCB (polychlorinated biphenyl) disposal is relatively easy by comparison and still it is the source of tremendous opposition. So the Nevada disposal site is a no go? It is because...what...infiltration when the climate turns wet and the generation of a plume that could go all the way to Death Valley and pop up as a radioactive hot spring?

OK...how about this...5 guys stood under a nuclear blast 18,000 ft up in the 50's and live till they are in their 80's or 90's. All sorts of this and that but these guys were 18,000 ft from ground zero and did OK! Yes yes...there are many cases where folks got compensation...OK already.

Now we are all going to go ape because we (meaning the many who oppose any nuclear anything) think there might be a problem what... 10,000 years in the future at a place 40 miles away in Death Valley?

OK...I'm game...prove me wrong. Waste storage in barrels is somehow safe for the time being and we don't know if granite is?

Five Men Agree To Stand Directly Under An Exploding Nuclear Bomb : Krulwich Wonders... : NPR

Wfm_area51_map_en.png (1382×980) (wikimedia.org)

Steve Johnson, you are quite right, leaving high level radioactive waste on the surface must be far worse than putting it underground in granite. But neither place is a great idea for something that will remain toxic and hot for tens of thousands of years. Ten thousand years is longer than all of the civilisations that have existed on Earth. Our short term use of electricity leaves a huge legacy for the future.

And you are right about the bureaucrats/politicians who will not make a decision, because whatever decision they make will be unpopular. In Australia we only have one small research reactor and our politicians will not make a decision about where to store even the low level radioactive waste.

Sorry, this post is not exactly research, but it does relate to the original question, and does involve input from scientists.

The Uranium Rare Earth Elements-rich mineral Davidite in the mineralized shear zones of the Tete (Mozambique) seems to have kept its hazardous elements tightly locked in ... I suggest that somebody should go there and study the colloids-mediated-dispersion of the actinides in the groundwater like it was done in Gabon (Oklo) and Brazil (Pocos da Caldas). The advantage of the Mozambiquian uranium ore is that it would would provide a fairly close a natural analogue of ANSTO's Synrock (compound of three titanate minerals).

It could be, but it depends on the overall geological/ geochemical situation of the individual site and the disposal concept. Typically, granite as well as other crystalline host rocks are fractured and are rather permeable for water (much more than salt or clay rock). So, the safety of the facility depends on the technical barriers employed to encapsulate the waste (container, buffer), whereas in clay and salt the host rock itself is the main barrier. Multiple projects in crystalline rock are on the way worldwide, several others are under investigation. After decades of research and intensive safety assessments, Finland and Sweden have selected and licensed sites for the disposal of nuclear waste in granite rock. Some other countries favour clay rock (e.g., France, Switzerland) or investigate options to use salt rock instead.

An underground storage facility for nuclear waste has been prepared many years ago in Central Canada, but has not been used yet. It is a km and a half deep in granite. When the local residents were asked whether it should be used for storage, they voted NO. Maybe if they were told it would bring millions of $ to the community, they would have voted YES.