Friday, September 30, 2011

Follow-up: Is spent fuel repository space truly "scarce?"

An anonymous commenter* left a response this evening to my most recent post criticizing the BRC's chief reliance on interim storage as a waste management solution. [*While it is generally my policy to be quite liberal with anonymous commenting (and I would never demand anyone disclose their real identity without so choosing), it is perhaps helpful for responding to anonymous comments to provide some kind of pseudonym or handle. As it is, this is simply a personal preference, no more.]

Ordinarily, I would simply respond in the thread, however the commenter raised several intelligent and interesting points which are worth responding to more broadly.

Taking it piece-by-piece:
The BRC report actually does recommend a decision framework for adopting advanced future fuel cycle technologies (including reprocessing). The report says that the federal government should sponsor RD&D to develop and demonstrate these technologies, but that the federal government (and the federal corporation recommended by the BRC) should not build or operate such infrastructure. So any future closing of the fuel cycle would involve decisions made by the private sector, based upon economics of direct disposal versus recycle. There it is.
Yes, it is true the report states just that. However, as I pointed out previously, the BRC report does not address any of the incentive structure built into the current waste fee, which charges based upon electricity demand rather than final impact upon the repository. By the current policy, private operators have no incentive to reprocess until the value of spent fuel exceeds the direct cost of reprocessing in addition to fees already paid for disposal. (There is likewise the issue that the fuel is held in title by the federal government).

In this sense then, it is not per current law the province of the private market to solve. This is at the root of the reason that I point out the flawed incentive structure, however - right now, the current policy of pay-as-you-produce, per unit electricity fundamentally short-circuits decisions by the private market by forcing them to pay a fixed cost for disposal no matter what. A revised policy which rested on A) Payment at time of disposal, and B) Fees adjusted to repository-impacting factors such as volume and heat would allow for this kind of private decision-making process to take place.

In other words, right now any market for private action on spent fuel is essentially a stacked deck, which the BRC recommendations do little to address.

Further, because without further changes to the Nuclear Waste Policy Act, spent fuel is the legal responsibility of the federal government, disclaiming technological alternatives to direct disposal without modifying the legal or fee-structure process is itself a commitment to direct disposal, absent events which entail spent fuel having a commercial value above and beyond that which has already been paid over to the federal government. Again, even a policy which delays these payments until spent fuel is handed over for final disposal would help to correct this issue.

As of now, given the fact that the federal government assumes a monopoly over spent fuel, it's a bit of a mulligan to argue that the private market serves as the decision framework for spent fuel treatment alternatives.
This post states that "The overall capacity of a geologic repository is controlled chiefly by temperature" which is not really correct; the overall capacity of a repository is determined primarily by the repository's area. The post presumes that repository area will remain a scarce resource, making closing the fuel cycle necessary to use limited repository area efficiently. This is a potentially completely incorrect assumption. What is the area of bedded salt in the Permean basin that stretches from Texas to Louisiana to Kansas? What is the area of the 70% of the continental U.S. which has crystalline basement rock within 2 kilometers of the surface suitable for deep boreholes? How many ridges of volcanic tuff are there at the Nevada Test Site that have ground water over 1000 feet below the surface? How much granite, how much clay does the U.S. have?
Let's break this into two issues. Assuming fixed physical design (i.e., footprint), temperature is a limiting factor. This is not really a matter of dispute. The temperature of the drift wall and the rock between drifts is what controls the physical emplacement of waste.

Yes, one can always dig a bigger hole - or for that matter, look into alternatives such as vertical emplacement rather than the current model for horizontal emplacement. And indeed, by this logic, we conceivably aren't restricted in terms of available repository space - which is why I took care to point out that this is a regulatory limit in the context of Yucca Mountain (based upon the design itself) rather than a strictly technical one. However, the political feasibility of this approach of indefinite expansion has always been in doubt (difficulties in opening one limited-scale geologic repository notwithstanding). I am extremely pessimistic that one can simply get away with indefinite expansion of capacity at a single site, despite what is easily sufficient physical capacity to do so.

Moving on to the broader point regarding available alternative disposal sites, this is actually a point I've been wanting to address in a future follow-up about geologic disposal alternatives (i.e., alternatives to the Yucca Mountain geology). Indeed, the Permian basin salt dome formation is quite large, and was the subject of the aforementioned "Project Salt Vault," which originally tested the feasibility of salt-dome formations. (Likewise, WIPP is also on the border of this same formation).

Deaf Smith county, Texas, one of the five original sites nominated for a permanent geologic repository, was also located in the Permian basin geology, which indeed is quite expansive, with many locations isolated from population centers. Other locations considered, such as Hanford feature granite in the saturated zone. The list goes on.

So, are we limited in terms of available site selection for geologic repositories? Physically, no - nor was this the problem to begin with. However, I would argue on the basis of history that we are greatly constrained politically in opening such a repository. While I welcome the BRC report's emphasis upon a consent-based process for repository siting, I am pessimistic that the NIMBY politics which mired down a site selection process originally would not make opening or expanding future sites another difficult and time-consuming process. I would thus argue that repository space thus is at a premium, not for want of accommodating geology but for lack of political will, something which appears to evolve only on the same timescales as geology itself. (Again, somewhere I'd be happy to be proven wrong.)

On the topic of boreholes - this is one area where the BRC report appeared to favor further investigation - however the one remark I can provide here is that deep borehole disposal is relatively expensive - then again, so are geologic repositories. Cost estimates seem to vary wildly based upon the assessment, with some studies indicating an array of 700 boreholes to dispose of 70,000 MTHM of waste would cost about $14 billion. Looking back to a study performed by a former colleague, it would appear that their estimate for 95 boreholes (for 10,000 cubic meters of storage, or about the equivalent of 36,000 MT of SNF) would be about $3.26 billion - still less than a tenth of the estimated cost of Yucca Mountain and about a quarter of the estimated cost of a similar geologic repository in Sweden. (Note that this study is for intermediate-depth boreholes for greater-than-class-C waste; actual requirements for intact spent fuel may vary.)
In this sense then, issues of future retrievability and ultimate technical feasibility aside, deep borehole disposal may indeed be the way to go. This begs the question (to which I have no immediate answer) why the original Nuclear Waste Policy Act and subsequent amendments were thus so committed to the strategy of centralized geologic repositories, as opposed to decentralized disposal in deep boreholes.
Will the private sector ever want to invest in building reprocessing infrastructure that could become uneconomic overnight as soon as a few square miles of new repository space are opened up?
Historically, this factor didn't seem to stop investments at West Valley and Barnwell. While West Valley was ultimately ill-fated due to initial design issues and later rendered retroactively uneconomical by changing regulations, Barnwell was clearly an attempt by the private sector to directly address spent fuel reprocessing. One can dispute whether the economics ever favored the viability of Barnwell, however clearly the private sector has been willing in the past to take on some of this infrastructure.
Further, this assumes a relative ease in developing repository capacity which again, may not be technically constrained, but certainly has yet to be demonstrated in terms of political feasibility.
If the decision to recycle spent fuel is left to the private sector, as the BRC recommends, probably the only reason any significant amount of spent fuel will get recycled in the future is because new reactor technologies will be commercialized where fissile recovered from old spent fuel will be less expensive than fissile from natural uranium. Google "denatured molten salt reactor" for a plausible example.
If the BRC recommendations are followed with no further amendment to the Nuclear Waste Policy Act (specifically with regard to the fee structure), this is likely true. And certainly, there are plenty of examples of reactor concepts which make use of recovered fissile materials, ranging from the integral fast reactor (a perennial favorite of Barry Brook over at Brave New Climate) to the EM2 small modular reactor design being proposed by General Atomics.

However, once again I believe my criticism here is still salient - how will the chain of custody of spent fuel adapt to allow for private alternatives to direct disposal? Will the federal government rebate funds for fuel diverted for recovery? Will an alternative fee be assessed for waste forms which are either more compact or cooler (thus having a lower marginal impact on the repository capacity?) These are questions which are left unanswered, ones which I believe would have significant consequences for private incentives for nuclear waste management (including recovery for reactors).

Given my own personal political preferences, I would prefer to see a system in which the private market handled spent fuel and the federal government only served in the role of steward of geologic disposal sites. However, in my opinion this requires a more fundamental re-working of the incentives built in to the Nuclear Waste Policy Act, which has yet to be proposed by the BRC.

Overall, several good and provocative points raised by the commenter - I appreciate their taking the time to present such a thought-out response, and hope this post serves to further the discussion.