More on that 100,000-year ‘tail risk’ | FT Alphaville

More on that 100,000-year ‘tail risk’

The above is a presentation from a representative of Tokyo Electric Power on the subject of spent fuel storage at the Fukushima nuclear power plant. In November 2010, it was delivered to the IAEA.

In March 2011, it understandably went viral.

We recently noted the presentation ourselves. Reuters has now delved into the report in detail:

Fukushima Daiichi had over time been pushing the limits of the plant’s capacity to store uranium fuel on site…

The TEPCO presentation noted that the utility had taken steps to increase storage capacity for spent fuel at the plant complex beyond its original design. Those included “re-racking” the pools in the reactor buildings to increase their capacity and then building a separate large, pool outside and a separate hub of metal casks that do not need to rely on electricity.

But the only significant open space left for storage remained inside the reactor buildings, according to the document. TEPCO had the capacity to more than double the number of fuel assemblies stored in the reactors from 3,998 at the time of the quake to 8,310 assemblies.

Here’s the relevant presentation slide (click to enlarge):

(What if they had gone on to double fuel assemblies within the structure and the earthquake had hit after that point?)

Lastly, from the Tepco presentation, it’s once again not quite clear if anyone is really taking account of the full storage time needed for these fuels.

Off-site storage for Fukushima coming online in 2012 will store 20 years of fuel for 50 years. And then? You can count many fuels’ half-lives in the 10,000s of years. In fairness to Tepco, they were trying out dry storage casks that can last a while, and which survived the quake very well (they don’t need electricity). There’s still a long lead time required to build and test the casks though.


Back to tail risk

Add it all up and we have more data for our original question. Was Fukushima a black swan no one could have seen, or a tail risk that could be measured and was moreover, man-made? We would now modify the question a bit further in light of all this extra data. What here is really true tail risk, and what is the outcome of institutional path dependence that was, eventually, taken for granted?

There is a lot of habituation and path dependence surrounding Fukushima. Not just within the nuclear industry — light water reactors themselves for instance– but also when we consider alternatives to nuclear, and their own heavy costs, not to forget a very different 100,000-year problem for humanity: if fossil fuel depletes rapidly and transforms the climate, there is no way we’ll survive that long.

In that case…

It’s really a question not of whether tail risk is measurable (it is), it’s whether our brains are kitted out to comprehend or reliably bear in mind even a measured tail risk in the first place.

And in that case…

You can see why Fukushima might end up a useful case study for financial markets in general, one day soon.

Related links:
Black Swan fatigue – FT Alphaville
Japan: The nuclear backlash – FT Alphaville
More on Spent Fuel Pools at Fukushima – Union of Concerned Scientists