TECHNICAL | DEEP DISPOSAL


LOOKING VERY DEEP FOR DISPOSAL


Conventional thinking suggests nuclear waste should be disposed of in deep geological repositories not much more than a few hundred metres below ground. Deep directional drilling techniques pioneered and now mastered by the oil and gas industry offer are alternative solution. By Dr. Henry Crichlow, founder and CEO of NuclearSAFE Technology LLC


Nuclear power may be the new green, except for one considerable problem. The nuclear power industry struggles to get rid of its toxic waste. As recently stated, “deep geological repositories (DGR) are the globally preferred and scientifically proven solution to store high level waste”. However, this hinges on how you define ‘deep.’ Current DGR sites are really mislabeled as they are planned to be a mere 60m to 800m below ground level. In terms of high-level waste, that is totally inadequate. To be truly effective, DGRs must be significantly deeper. Since the 1970s, several countries have sought to


manage the disposal of nuclear waste. In spite of those efforts, the waste product is still here and accumulating with no solution in sight. However, today there is an alternative solution. A deep horizontal wellbore disposal system drilled in a closed geological formation, 3000m or more below the surface.


Below, figure 1:


Current state of nuclear waste disposal proposals


TIME TO DIG DEEP All current ‘deep’ repository plans or efforts are in fact near surface storage and aim to dispose of high-level waste in shallow surface tunnels or mines. Many are so shallow they are actually in the existing water table. Although alternative solutions have been available and known in the public domain since the late 1990s,


NOT TO SCALE


600m


Near surface water table


SuperLAT™ rig


Canada 600m


the agencies responsible for current designs appear fully committed to blindly following each other, each spending billions of dollars over several decades developing ‘one-shot’ DGR systems. In such systems, a flaw or mistake discovered at any point in this process will mean a total loss, with all the years and dollars invested being wasted. With no shortage of time and money invested, what is missing is innovation. Nothing has changed in the waste technology since the efforts to establish the Yucca Mountain repository in the US more than 40 years ago, a shuttered site properly emblematic of the current DGR ‘solution.’ As the long-running issues faced at Yucca Mountain


demonstrate, near-surface repositories may be of questionable merit. Developers anticipate that by installing bentonite ‘backfill’ or titanium ‘umbrellas’, that these add-ons may guarantee some protective longevity, all at extreme costs and risks. However, any man-made protection exposed to water will be unable to withstand corrosion for the amount of time necessary. Luckily, an alternative solution already exists: disposal in deep horizontal wellbores, drilled and completed below 3000m deep in solid rock zones. This is a better solution for many reasons. The deep horizontal disposal repository in closed geological formations reaches far below any known water table. This disposal operation is also possible today. And it is much less expensive. For these reasons, it is a superior alternative to the current near surface DGR systems.


Ground level


France 500m


Japan 300m


Sweden/Finland 400m


Yucca Mt. USA 0m


(surface)


5,000m below


the surface SuperLAT™ 5,000m deep


1,000 waste capsules in 4,000m lateral


Eiffel Tower


DEEP HORIZONTAL WELLBORES - BUILT-IN REDUNDANCY Firstly, wellbore repository systems are drilled vertically downward to at least 3000m below the surface, far deeper than existing DGR systems. Next, the wellbores are turned, extending horizontally for at least 5000m laterally. The lateral section can then be reamed out to the desired wellbore diameter. As shown in Figure 2, this innovative drilling operation provides a continuous closed communicative pathway, from the surface, inside multiple durable steel casings which are lined externally with a robust cement annuli. While a novel application, the design is a modification


of oilfield downhole tools that have been in use for many years. This engineering approach is the core of


44 | July 2023


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