Fukushima and Beyond

April 27, 2011 § 1 Comment

Source: Areva

This is fairly representative of the discussions at the Breakfast Forum held on April 21

The Fukushima Daiichi disaster is now classed with Chernobyl in magnitude.  It is clear that the single most significant cause of the radiation leakage was the power blackout.  The cascade of events began with the tsunami, which breached the wall.  Tsunamis are classed by the height of the wave upon shore impact.  This one was judged to be at 46 ft and the breach occurred because the seawall was designed for 19 ft.  Two previous tsunamis, in 1933 and 1896, had reportedly been substantially higher than this one.  The numbers themselves may be somewhat suspect because these measurements are not standardized, and certainly were not a century ago.  Nevertheless, the seawall appears to have been under designed.

The flooding caused what is known as a station blackout.  No power of any sort.  The primary reason for this appears to be that the backup diesel generators were in the basement, and got flooded.  The reactor had in fact been shut down well before the wave hit.  But nuclear reactors continue to generate heat after shut down, although this progressively decreases.  Cooling water is required, in the absence of which the fuel melts and releases radioactivity.  Due to extended power failure the core sustained damage.  The resulting reaction with water produced free hydrogen.  The systems designed to prevent explosion of this hydrogen did not function, in part due to the lack of power.

The power loss was the single weakest link in the chain.  The significance of this to the US situation is that spent fuel is stored in a water-cooled environment at 80 locations and these are largely already at full capacity.  This is occasioned by the policy decision to not store at Yucca Mountain.  So, while tsunami mediated flooding is not likely on the mainland, power loss due to other reasons, including sabotage, cannot be ignored.

Policy Implications:  Each new disaster increases the understanding of some aspect of the cause of catastrophic events.  Corrective actions are taken and the next one likely has a different root cause.  This does raise a question regarding the futility of attempting to prevent Black Swan or Perfect Storm (take your pick on popular descriptors) events.  The generally held belief is that these are results of combinations of very low probability events.  So further decreasing the probability of each is possibly not terribly productive.  But doing nothing in the face of calamity is simply not an option.  Besides, in the case of Macondo, certain measures have emerged which definitely will improve overall safety.  In this one, a clear finding with broad scale implications is that of the loss of cooling and the implications to back up power and other safeguards.  The applicability to spent fuel storage is direct and decidedly important.  Were it not for this incident, the public certainly would have seen the spent fuel repository debate as relegated to the cognoscenti.  Now they can be communicated to with simplicity and accuracy on the risks of distributed storage.  Maybe, just maybe, this particular ostrich will raise its head out of the sand and we will get a national plan that makes economic and environmental sense, and yet is responsive to the nuclear proliferation concerns.

The time span between major energy related incidents was 25 years in this case and 30 years for deepwater oil spills.  One cannot help but wonder whether complacency is a factor.  Certainly in the case of the Macondo spill, industry experts have acknowledged this as a factor.  One theory advanced in our Breakfast Forum was that of worker training and longevity on the job.  The Navy was cited as an organization that deals with reactors routinely but does so with a workforce that is exceedingly well-trained and with strict safeguards.  The energy industry tends to be cyclic and profit motivation is definitely in play, as repeatedly alleged with regard to BP in the Macondo incident.  Regulation, preferably self imposed by industry, could address the matter.

Of interest is the observation to date that the earthquake per se did not damage the reactor.  This despite the fact that at 9 on the Richter scale, this is one of largest ever recorded.  California can take some measure of comfort, one assumes.

Consequences to Power Production:  Germany has already reacted to withdraw the permit to extend the life of about 8 reactors, which is a reversal of an earlier decision.  Switzerland is stopping issuance of new permits.  Any country that takes measures such as these is left with few choices.  The principal one is natural gas generation.  In the case of Germany, this means increased reliance on Russian gas or LNG imports.  Also, replacing nuclear with gas creates a carbon deficit.  All previous scenarios for carbon mitigation relied heavily on nuclear as a zero carbon source.  To the extent that this is seriously compromised, the low carbon future targets are even greater jeopardy.

Wind is the leading candidate to provide a carbon credit.  It is closer than solar in achieving parity with conventional sources.  One feature in its favor is that it is highly modular; production can commence quickly even as more capacity is being added, provided the delivery infrastructure is in place.  Aside from the fact it too is buffeted by environmental and aesthetic opposition, the diurnal aspect appears to limit the total contribution in a given area.  Many believe the cap to be around 20% but credible studies supporting a particular number are not in evidence.  Also, we don’t know the extent to which new storage measures and the smart grid could ameliorate this drawback.

The nuclear option faces an interesting dilemma.  Already burdened by high capital costs and long lead time to first production, the additional risk is bound to increase the discount rate.  This will increase the investment even more.  Purely from the standpoint of economics, extending the permit life of existing reactors, albeit with improvements, will be the economically driven choice.  The irony here is that this will perpetuate older, and presumably somewhat less safe, technology.

All energy comes with a price.  It is a question of choice.  You can’t leave it, so best learn to love it.



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§ One Response to Fukushima and Beyond

  • LoboSolo says:

    Well let’s face it. In hindsight, putting a backup diesel generator in a basement when there is a possibility of a tsunami doesn’t seem like a good idea. But how big of a generator does it take to operate the cooling pumps? Why did it take so long to get a replacement? These are a few things to look at for current plants.

    Going forward, we need to move away from PWRs (Pressure Water Reactors) to MSR (Molten Salt Reactors). These are passively cooled and cannot overheat. I lean towards the LFTR (Liquid Floride Thorium Reactor).

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