“Deep Isolation”: The Solution to High Level Nuclear Waste?

“Deep Isolation”: The Solution to High Level Nuclear Waste?

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Guest commentary by David Middleton

Hat tip to Dr. Willie Soon

The Deep Isolation concept is a proposal by Dr. Richard Muller (of BEST “fame”) and his wife Elizabeth Muller.  The team also includes our good friend Steve Mosher.

Steve Mosher, Director for Asia/Pacific A scientist at Berkeley Earth, Moser has written and maintains several R-packages devoted to analyzing temperature and climate data with open source tools. He has recently transitioned to the consumer sector and specializes in bringing new technology to market. (Mosh… They spelled your name wrong.) Deep Isolation Team

While I didn’t see many (or any) drilling engineers in their “roster,” they do list Scott Tinker, Director of the Bureau of Economic Geology at the University of Texas as a member of their advisory board.  The Texas BEG has in the past evaluated East Texas salt domes as potential nuclear repositories.

Right after reprocessing spent nuclear fuel, geologic sequestration is the second best solution for high level nuclear waste.  This is from the Deep Isolation FAQ’s page:

Deep Isolation Technology

What is the Deep Isolation concept, in simple terms?

Rather than use large tunnels, Deep Isolation will place nuclear waste in narrow (8 to 14 inch in diameter) horizontal drillholes in rock that has been stable for tens of millions of years. No humans need to go underground. The small diameter drillholes are markedly different than the 18 to 25-foot diameter tunnels of the planned Yucca Mountain repository.

Deep Isolation drillholes will go down about a mile vertically and then gently turn horizontal. The waste would be stored in the deep horizontal section. This approach has several key benefits. First, horizontal drillholes, especially with an upward tilt and a “plumber’s trap” can prevent radioactive material from reaching the vertical portion of the borehole, and reduce dependency on man-made barriers. Second, placing the canisters in a long horizontal borehole increases the storage room without having to drill overly deep (at which point pressure can increase cost), or to have to worry about stacked canisters being crushed by their own weight.

The drilling industry has already perfected ways to place objects in deep boreholes, and retrieve them, all robotically.

For a visual summary of a Deep Isolation borehole, see Figure 3 at the end of this document.

Can you really put three miles of continuous steel liner (a “casing”) down the drillhole (1 mile of vertical access and 2 miles of horizontal storage)? How does it get around the curved section?

Doing so has become straightforward in the drilling industry. The rig set up above the drillhole is used to support the drilling system, and also to place the continuous steel casing into the hole. In the rig, 40-foot-long sections of casing are screwed together as they are lowered into the hole. The curved region that transitions from a vertical to a horizontal borehole has typically a 700-foot radius of curvature, and the steel casing flexes easily around this bend. This has been done in over 50,000 drillholes in the US in the last two decades.

Do you pick sites that are suitable for gas and oil recovery?

The ideal geology for waste isolation has no recoverable natural resources. We prefer rock that is ductile, so it is fracture resistant. Typically, this means clay-rich, and this feature makes the rock unsuitable for fracking.

Why didn’t someone think of this before?

The Yucca Mountain tunnel repository was chosen by the US government in the 1980s, due for completion in 1998, before the new drilling technologies were highly developed. When the Yucca Mountain facility ran into physical and political problems, no alternatives could be considered because the Nuclear Waste Policy Act specified that they could not be licensed.  Our solution provides an additional disposition pathway for commercial spent nuclear fuel and DOE nuclear waste inventories and should be considered as a second disposal option.

Can all that waste fit in narrow drillholes?

Spent nuclear fuel is compact, amounting to only 2 cubic meters per year for a gigawatt (thousand megawatt) reactor. Coal waste takes over a million times as much volume. One drill hole has 1000 cubic meters of space, enough for 20-reactor years of waste, assuming that we do no repackaging of the fuel assemblies. The assemblies that hold the waste fit in long narrow canisters that can be lowered into a drillhole.

What keeps the radioactivity from reaching the surface?

The Deep Isolation design relies on both engineered and geological barriers so there is built-in redundancy to the system.

The deep geology of the Deep Isolation design is a significant barrier. If there were to be any releases, they would have to get through a mile of rock, over a billion tons, including layers that have held volatiles (methane) for millions of years.

Additional engineered barriers include the ceramic pellets themselves, the metal rods that contain them, the bentonite surrounding the rods, sealed steel canisters that hold the rod assemblies, steel casing that lines the drillhole, and the cement that fills the space between the casing and the drillhole.

For geologic times, the geology is a key barrier. The geologic formations that would be used have been stable for tens of millions of years.

Why a mile deep?

The waste is placed far below aquifers, in regions in which water has had no contact with the surface for a million years or more. We will dispose in or under geologic formations that have been stable for tens of millions of years. Typically, this means a depth of about a mile, but in some locations it could be as shallow as 3000 feet, or as deep as 10,000 feet. Drilling such holes is now routine, and the drilling industry has made over 50,000 of such horizontal drillholes over the last 20 years.

[…]

Can the waste be retrieved?

Yes. The drilling industry regularly retrieves objects and monitoring instruments from boreholes, and the process is standard. Once the vertical drillhole is sealed, an expert crew could still retrieve the waste, but it would take a week or possibly longer. Doing so is sufficiently complex to offer substantial security from a terrorist attempt

[…]

Deep Isolation FAQ’s

A few thoughts on this:

Can you really put three miles of continuous steel liner (a “casing”) down the drillhole (1 mile of vertical access and 2 miles of horizontal storage)?

 

Yes.  We do this every day of the week in oil & gas drilling.

Do you pick sites that are suitable for gas and oil recovery?

The ideal geology for waste isolation has no recoverable natural resources. We prefer rock that is ductile, so it is fracture resistant. Typically, this means clay-rich, and this feature makes the rock unsuitable for fracking.

Shale is generally a clay-rich rock…

What is shale?
A strict geological definition of shale is any “laminated, indurated (consolidated) rock with > 67% clay-sized materials” (Jackson, 1997). Approximately 50% of all sedimentary rocks are classified as shale. Shales are often deposited in low-energy depositional environments where the fine-grained clay particles fall out of suspension.

Reference: Jackson, J.A. (1997). Glossary of Geology, 4th Ed. American Geological Institute

Halliburton

While “clay-sized materials” doesn’t necessarily require clay mineralogy, most of the shales that are frac’ed are fairly abundant in clay mineralogy.

Ductile shales tend to have low quartz and carbonate fractions and tend to plot more or less in the center of this ternary diagram:

“Fig. 1. Ternary diagram of all shales in database. The color represents the individual shale, and the size of the bubble represents the brittleness as determined from XRD data (computed by mineral composition).” Halliburton

If they’re planning on drilling these horizontal disposal wells in areas unsuitable for frac’ing… There’s not likely to be a lot of well data… So I’m not sure how they plan to identify ductile shale formations at depth.  I suppose they could focus on failed shale plays, where the rocks were unsuitable for frac’ing.

The Texas BEG did take a serious look at using East Texas salt domes as waste repositories (Jackson & Seni, 1984).  Salt (halite) is very ductile and generally clay-free.

Why a mile deep?

The waste is placed far below aquifers, in regions in which water has had no contact with the surface for a million years or more. We will dispose in or under geologic formations that have been stable for tens of millions of years. Typically, this means a depth of about a mile, but in some locations it could be as shallow as 3000 feet, or as deep as 10,000 feet. Drilling such holes is now routine, and the drilling industry has made over 50,000 of such horizontal drillholes over the last 20 years.

There’s no “magic” depth.  Each site would have to be evaluated in detail.

Can the waste be retrieved?

Yes. The drilling industry regularly retrieves objects and monitoring instruments from boreholes, and the process is standard. Once the vertical drillhole is sealed, an expert crew could still retrieve the waste, but it would take a week or possibly longer. Doing so is sufficiently complex to offer substantial security from a terrorist attempt.

“The drilling industry regularly retrieves objects and monitoring instruments from boreholes” that were designed to be retrieved: wireline logging instruments, drill strings, etc.  “Once the vertical drillhole is sealed,” the removal of objects designed to stay in the well are expensive and time-consuming to retrieve, if they are even retrievable.  The one drawback to this sort of disposal system is that, unlike cavernous facilities, retrieval of disposed waste is extremely difficult.  This sort of method is more suitable to permanent disposal.

Why didn’t someone think of this before?

 

Someone did think of it before…

 

SANDIA REPORT

SAND2009-4401

Unlimited Release

Printed July 2009

Deep Borehole Disposal of High-Level Radioactive Waste

Patrick V. Brady, Bill W. Arnold, Geoff A. Freeze, Peter N. Swift, Stephen J. Bauer, Joseph L.  Kanney, Robert P. Rechard, Joshua S. Stein

Prepared by

Sandia National Laboratories Albuquerque, New Mexico 87185 and Livermore, California 94550

[…]

Preliminary evaluation of deep borehole disposal of high-level radioactive waste and spent nuclear fuel indicates the potential for excellent long-term safety performance at costs competitive with mined repositories. Significant fluid flow through basementrock is prevented, in part, by low permeabilities, poorly connected transport pathways, and overburden self-sealing. Deep fluids also resist vertical movement because they are density stratified. Thermal hydrologic calculations estimate the thermal pulse from emplaced waste to be small (less than 20° C at 10 meters from the borehole, for less than a few hundred years), and to result in maximum total vertical fluid movement of ~100 m. Reducing conditions will sharply limit solubilities of most dose-critical radionuclides at depth, and high ionic strengths of deep fluids will prevent colloidal transport.

[…]

DOE estimates that 109,300 metric tons heavy metal (MTHM) of high-level waste and spent nuclear fuel – primarily commercial spent nuclear fuel (CSNF), but also DOE spent nuclear fuel (DSNF), and high-level waste glass (HLWG) – will need to be disposed of in the US (the projected US HLW and SNF inventory is summarized in Appendix A).,Deep borehole disposal, characterization and excavation costs should scale linearly with waste inventory: small inventories require fewer boreholes; large inventories require more boreholes. Not needing a specially engineered waste package would also lower overall borehole disposal costs. Both aspects might make borehole disposal attractive for smaller national nuclear power efforts (having an inventory of 10,000 MTHM or less). In the US, the 70,000 MTHM of waste currently proposed for Yucca Mountain could be accommodated in about 600 deep boreholes (assuming each deep borehole had a 2 km long waste disposal zone that contained approximately 400 vertically stacked fuel assemblies). The remainder of the projected inventory of 109,300 MTHM could be fit into an additional 350 or so boreholes.

Because crystalline basement rocks are relatively common at 2-5 km depth (See Figure 2; also see O’Brien et al. 1979; Heiken et al. 1996), the US waste disposal burden might be shared by shipping waste to regional borehole disposal facilities. If located near existing waste inventories and production, shipping would be minimized. A disposal length of ~2km, and holes spaced 0.2km apart suggests the total projected US inventory could be disposed in several borehole fields totaling ~30 square kilometers.

Petroleum drilling costs have decreased to the point where boreholes are now routinely drilled to multi-kilometer depths. Research boreholes in Russia and Germany have been drilled to 8-12 km. The drilling costs for 950 deep boreholes to dispose of the entire 109,300 MTHM inventory, assuming a cost of $20 million per borehole (see Section 3.1), would be ~ $19 billion. Very rough estimates of other costs are $10 billion for associated site characterization, performance assessment analysis, and license application, $20 billion for disposal operations, monitoring, and decommissioning, $12 billion for ancillary program activities, and $10 billion for transportation, resulting in a total life-cycle cost for a hypothetical deep borehole disposal program of $71 billion (in 2007 dollars). Although there are significant uncertainties in the cost estimates for deep borehole disposal presented here, the estimated total life-cycle cost may be significantly lower than the estimated total cost of Yucca Mountain. Note in particular the lower construction/operation and transportation outlays that borehole disposal would allow.

This document outlines a technical and performance assessment analysis of deep borehole disposal of US HLW and SNF.

[…]

Sandia National Laboratories, 2009

Sandia.pngSandia.png

Left: Deep Borehole Disposal Schematic.  Right: Depth the Crystalline Basement Map

This is worth repeating:

The drilling costs for 950 deep boreholes to dispose of the entire 109,300 MTHM inventory, assuming a cost of $20 million per borehole (see Section 3.1), would be ~ $19 billion. Very rough estimates of other costs are $10 billion for associated site characterization, performance assessment analysis, and license application, $20 billion for disposal operations, monitoring, and decommissioning, $12 billion for ancillary program activities, and $10 billion for transportation, resulting in a total life-cycle cost for a hypothetical deep borehole disposal program of $71 billion (in 2007 dollars).

$71 billion (in 2007 dollars) to safely and permanently dispose of the entire inventory of 109,300 metric tons heavy metal (MTHM) of high-level waste and spent nuclear fuel.

That would be $84 billion in 2017 USD.

According to BP’s Statistical Review of World Energy June 2017, from 1965-2016, US nuclear generating stations produced 26,386 TWh of electricity (26.4 trillion kWh).

$84 billion divided by 26.4 trillion kWh is $0.0032/kWh… 1/3 of one penny per kWh to dispose of the entire inventory of high-level nuclear waste.

The geologic sequestration of high level nuclear waste is almost trivial.

The main difference between the Sandia proposal and Deep Isolation is that the former would have permanently disposed of the waste in vertical wellbores drilled into crystalline basement rocks below sedimentary basins (~17,000′ below the surface); whereas Deep Isolation would dispose of the waste in “retrievable” horizontal boreholes in sedimentary rocks (~5,300′ below the surface).

Conclusion

It’s nice to see the BEST folks doing something useful.  It’s an interesting concept.  I just tend to think that it makes more sense to permanently dispose of the waste in deep wells, drilled into crystalline basement rocks, rather than shale formations in sedimentary basins.

Superforest,Climate Change

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