Sunday, May 29, 2011

Having A Nuclear Blast

This is an entirely expected development.  The current storm may well miss the Fukushima area, but at some point this hurricane season a part of a storm will move across it.  TEPCO has been spraying the grounds of Fukushima Dai-ichi with a resin that should, if it operates as claimed, reduce the amount of radioactive material transported by the wind and rain.  It probably works okay in a normal rain, but even cyclones that are only tropical storms can bring very heavy rainfall to an area.  It won't matter if the surface is sealed when large sections of ground are washed away, as happened on Thursday night here in Vermont.

Another issue of concern is the structural integrity of the unit 4 containment building, which seems to be leaning to the right a bit.  If it is seriously compromised, a big wind gust could create a crack in the spent fuel pool.  TEPCO announced that it had started shoring up the structure on May 9, but I am unaware of further updates on that matter.  Earlier speculation that the fuel pool had drained due damage was wrong, fortunately, but it could still happen.

On top of the existing technical problems at the site is this little incident (which will probably be resolved in a few hours, but still).

The most significant development in the Fukushima crisis over the past few weeks is the revelation from TEPCO that the fuel in units 1-3 melted down shortly after the quake and (and!) they knew it, at least for unit 1.  Given that pattern of lying, and the Japanese government's servile attitude towards TEPCO, I think it's advisable to heavily discount anything they say.

Finally, this presentation by Arnie Gundersen for the Advisory Committee on Reactor Safeguards is very important for everyone to see, despite a few technical annoyances.  It wasn't until a few weeks ago when he first mentioned it that I realized that the NRC assumed that there was zero probability (0.0%) that the containment structure at a nuclear reactor could fail.  Containment isn't the reactor pressure vessel; failure is assumed for that, even if the probability is low.  Instead, it is the larger structure built around the reactor pressure vessel.  For PWRs, it is usually the entire volume of a large, circular concrete building with a domed top.  For BWRs, it is usually a substructure within a large, square building, just like the ones at Fukushima.  (There are exceptions to each, of course, and other types of reactors, but not in the US.)  Gundersen has documented several instances where there were cracks or other penetrations in the containment at US reactors.  Now, in the first real-world tests of the GE BWR Mark I containment design, there has been 100% failure.  Three out of the three units that were online at Fukushima immediately prior to the earthquake and tsunami are compromised.  Those results should cause the NRC put any action such as license renewal or power up-rates for the 23 operating Mk.I reactors in the US on hold until what happened at Fukushima is fully analyzed and any lessons extracted.  That is unlikely to happen, unfortunately.  We seem to be living in a post-fact world, where only money and power can change people's minds.  The ACRS is likely to blow off Gundersen, as they have before.

ETA: Just after posting I found a report saying cooling has been restored.

Added 2011/06/01: Shoring up the unit 4 spent fuel pool started on 05/23 according to this article.

Saturday, May 28, 2011

Completed Insanity

A while ago I started a project to redraw the counties of California.  This morning, for no reason I can discern, I suddenly had the urge to complete the project.  And I did, at least as far as I'm willing to take it.  And here's the final result: new maps of Northern, Central, and Southern California.  I also made a few exports from the GIS program I used to determine where to place the boundaries.

In these images, the old borders and county names are in black, the new borders are in red, and the new names are in blue.  In the background are major roads in light purple, and national parks in olive.
Gone are all the arbitrary lines laid down when the surveyors divided up the land.  The new boundaries mostly follow either watershed divides or major water bodies.  There are exceptions, but I tried to limit them as much as possible.  The straight lines that you can see here exist because the boundaries I drew are approximations.  If this exercise were ever to be repeated for real, almost all of them would go away.
I ended up creating 13 new counties (McCloud, Whiskeytown, Tahoe, Hayward, Livermore, Shaver, Santa Maria, San Fernando, Antelope, Mojave, Palo Verde, Coacella, and Escondido), eliminating 14 (Shasta, Tehama, Glenn, Yuba, Nevada, Placer, Yolo, Amador, Calaveras, Alpine, Contra Costa, Madera, Kings, and Santa Barbara), and renaming 1 that had its signature feature removed (Eagle, from Lassen).
I significantly reshaped nearly every existing county.  The two least changed were San Francisco and Orange.

This image shows some of the other layers I used for reference.  Watershed outlines are in blue, and population density is represented by shading from light grey to black.
None of the resulting counties are ideal, and several have significant problems. Tulare County, for instance, is larger than I would like, but there is no non-arbitrary way to divide it. McCloud is probably underpopulated (though not any more so than neighboring Modoc).  And so on.  On the other had, the most problematic counties have been resolved in one way or another.  The minimally populated Alpine County has been eliminated, with the area mostly absorbed by Tahoe.  The ridiculously large San Bernardino has been divided between five different counties (though Mojave is still bigger nine states).  And Los Angeles is now entirely south of the San Gabriel and Santa Monica Mountains.

If there's a takeaway from this effort, it's that it is a good example of how poorly governed America currently is. There's no reason for the counties of California to exist as they do. They are artifacts of a situation where a literate, industrial culture invaded the lands of a number of pre-literate cultures that had been decimated by disease and warfare. If we better governed, somebody would have identified obvious problems like the size of San Bernardino, and organized society to resolve them. But for many reasons, nobody has done so.  That should cause us all to worry a bit.

Monday, May 23, 2011

This Time I Can Pronounce It

Unlike the last one, I can pronounce Grímsvötn, which is the volcano currently erupting in Iceland.

Friday, May 13, 2011

Generation Next

A few posts back I mentioned that the United States Department of Energy had come up with the concept of "generations" of nuclear reactors in order to help explain its current strategy.  The DOE is attempting to move forward on two different tracks: building Generation III reactors, which are supposedly improved designs of the light water reactors that were built in the 1970s and 1980s, and conducting research and development into what are hoped to be substantially better reactors to be built starting in the 2020s.  The progress on new Gen-III reactors was slow even before the Fukushima Dai-ichi crisis, mostly due to rapid cost escalation.  Reactor licensing by the Nuclear Regulatory Commission, which is an independent agency (from the DoE, but perhaps not from the nuclear industry), has also been slower than expected.  The crisis in Japan is likely to delay new Gen-III reactors further, and possibly derail the whole program.

Unlike the Gen-III effort, which is concerned mostly with domestic issues of implementation, the Generation IV program is an international effort.  Right now it's too early to say whether or not the Gen-IV program is on track - despite having been around for over a decade by now - because a lot of what participants are doing is basic materials research.  The effort is also somewhat diffuse, as countries are really coordinating work more than they are working together.  That's probably natural, as funding for the research is still being provided by member countries.  And finally, it's hard to talk about the status of the effort as the latest GIF annual report hasn't been issued, and the DoE's status page is simply out of date.

The most important achievement of the GIF so far has been to select six conceptual designs for further research.  (Note: most of the early GIF documents are no longer available from government websites, but some have been mirrored here.)  At least 94 different concepts were submitted for review in early 2001.  A number of meetings were then held to classify and evaluate the concepts.  The result was a report which laid out the rational for selecting six proposals to be investigated further.  Those concepts are: the gas-cooled fast reactor (GFR),  the lead-cooled fast reactor (LFR), the molten-salt reactor (MSR), the sodium-cooled fast reactor (SFR), the super-critical water-cooled reactor (SCWR), and the very-high temperature reactor (VHTR).  If some of those reactor types sound familiar, that's because they've been built before without much success.  But the evaluation team evidently though they were worth a second look.  Each of the concepts has a few options for implementation outlined in the report.

You may have noticed that three of the reactors have "fast" in their name, which is a reference to the energy of the neutrons that cause the self-sustaining nuclear reaction in a reactor core.  The main advantage of fast neutron reactors is that they are able to "breed" large amounts of new fissionable elements during operation, which could potentially eliminate any uranium shortages for thousands or hundreds of thousands of years.  With some configuration changes, fast reactors are also able to "burn" spent fuel from existing thermal neutron reactors.  If successfully implemented on large scale, this feature would drastically reduced the amount of high-level waste that needs to be stored in expensive geological repositories.  Of the other three, one is a standard thermal neutron reactor, one is a thermal neutron reactor capable of breeding at a low rate, and the other can be configured either to have either thermal or epithermal neutrons.

Below is my short summary of each concept.  There are, of course, better summaries elsewhere, but I've added a bit of editorializing that (ahem) you just can't find elsewhere.

Sodium-cooled Fast Reactor - The SFR concept has been previously implemented the most number of times out of the six concepts.  It is a fast neutron reactor that uses liquid sodium as the coolant in the primary and secondary cooling loops.  In the past these reactors have been called liquid metal fast reactors (LMFR) or just fast breeder reactors (FBR).  To date, a total of 20 SFRs have been built and operated, though only four are operating now.  Of those still in use, only one produces electricity.  The rest exist for research purposes.  In addition to being able to breed more fissile material, the SFR has the advantage of providing high outlet temperature without requiring the high pressures found in LWRs.  The main disadvantage is that sodium is flammable when exposed to air, and explosive when in contact with water.  Most SFRs have used water in the tertiary coolant loop to generate steam for turbines, and water ingress into the secondary coolant loop has been a major problem.  Some newer proposals use carbon dioxide in the tertiary loop to avoid the problem of sodium's volatility.  My take on this concept is that it useful mainly for breeding in a nuclear power "ecosystem" that includes lots of non-breeder reactors.  The difficulties encountered during implementation so far have made the SFR non-economic for electricity generation when compared to LWRs.  I think that further research should be done on this concept, but focused on efficient breeding and ease of loading and unloading the fertile material.

Lead-cooled Fast Reactor - This concept is another liquid metal-cooled fast reactor, like the SFR.  To date no LFRs have been built, but a closely related design using lead-bismuth eutectic as a coolant was built by the Soviet Union to power some of its submarines.  It was not very successful, though that may have had more to do with the Soviet Union's military culture than the design itself.  As with the SFR, the main advantage of this concept is high outlet temperatures at low primary loop pressures.  Unlike sodium, liquid lead is not explosive when in contact with water, which eliminates the need for an intermediate loop.  However, it is highly corrosive to most steels, and activation products (created when neutrons interact with elements in the coolant) remain radioactive for a long time.  It also solidifies at a relatively high temperature, which makes handling difficult.  And it is very heavy.  The best application of this concept seems to be for very small nuclear reactors, on the order of  20-200 MWt, that can be shipped whole to a site and returned to a factory for processing.  I think further research on this concept should be done only for small reactors.

Very-High Temperature Reactor - The VHTR is gas-cooled thermal neutron reactor that uses helium in the primary cooling circuit.  It has previously been implemented a total of eight times, but only two examples are currently operating.  There are also a number of carbon dioxide-cooled reactors operating, but that gas can't meet the requirements of the VHTR program.  The main attraction of this type of reactor is a very high outlet temperature, which is useful for generating hydrogen from water and for supplying heat for other industrial processes.  The main disadvantage is very high temperatures in the core, which many materials can withstand, but not in combination with high radiation.  Another important disadvantage is a once-through fuel cycle, which would leave lots of hot fuel elements that would have to be dealt with for hundreds or thousands of years.  Helium is also somewhat tricky to contain, and expensive.  My take on this type of reactor is that it was selected when there was still a lot of buzz about using hydrogen to fuel motor vehicles.  The reasoning behind the so-called hydrogen economy no longer makes sense, as batteries have improved significantly and people have come to recognize the difficulties of using hydrogen in that way.  I think this concept should be dropped.  Unfortunately, the DOE has made the VHTR the first Gen-IV reactor it plans to build.  The Next Generation Nuclear Plant (NGNP) program will start soliciting design proposals from vendors late this year or in 2012.

Gas-cooled Fast Reactor - The GFR is a logical next step from the VHTR, combining both high temperatures and the ability to breed more fissile material.  However, it is not as effective at breeding as either the SFR, and it has the same disadvantages as the VHTR.  No examples have ever been built.  I think this concept should be dropped.

Super-Critical Water Reactor - This concept is the next logical step from existing PWRs and BWRs.  It would use light water at pressures above the critical point, beyond which water behaves like both a gas and a liquid.  It would have only one coolant loop, like a BWR.  The steam handling devices at the top of a BWR pressure vessel would be eliminated, allowing control rods to be inserted from the top as in a PWR.  There are coal-fired power plants that use super-critical water already in operation, so the balance-of-plant (BOP) for the SCWR should almost be off-the-shelf.  However, it is unknown if a reactor pressure vessel can safely operate at the extreme pressures needed.  This concept can either operate as a thermal neutron reactor, or an epithermal neutron reactor.  The later has allows for a low level of breeding, but makes loss of coolant accidents (LOCAs) potentially more dangerous.  Canada is working on a subtype of this reactor that would leverage its experience with heavy water reactors.  Because of its high degree of similarity to existing reactors, I think research on this concept should be continued, with a focus on answering questions about the safety of the pressure vessel as soon as possible. *

Molten Salt Reactor - The MSR is a concept quite unlike any of the others above in that it would not use solid fuel elements.  Instead, the fissile material would be dissolved in the coolant, which is a mixture of fluoride salts (salt is used here in the technical sense, not in reference to standard table salt).  The nuclear chain reaction would only take place in the reactor core, where the combination a large mass of the fuel-salt fluid and a graphite moderator would bring the mixture to criticality.  The hot salt would then be cooled by a secondary loop of salt, which would in turn transfer the heat to a gas or water tertiary loop.  The concept could operate as a thermal neutron breeder, producing enough new fissile material to fuel itself for years.  The concept is another that would provide high outlet temperatures at low pressures.  Despite it's exotic nature, an example of this reactor was built and operated briefly in the 1950s, and another was built and operated in the 1960s for several years.  The biggest disadvantages of this concept are that the salts are corrosive, and processing the salt to remove certain fission byproducts currently is expensive.  I think an increased pace of research into the MSR is warranted, as it has a number of positive aspects not found in any of the other reactor concepts.

There is one hybrid of these concepts to note, the molten salt-cooled reactor.  This reactor would use a core similar to the VHTR but use a molten salt in the primary cooling circuit.  I think the concept may be useful an intermediate step towards a fluid-fueled MSR, but only as a research reactor, not as a commercial design.

If resources were more plentiful, funding research into all of the six reactor concepts would be worthwhile.  There are commonalities between them all, and scientific research is certainly more productive than blowing up wedding parties in Central Asia.  But in the current budgetary environment, I think the focus should be on the SFR, SCWR, and MSR concepts, with a limited additional amount directed towards small LFRs.

* Added 2011/05/14: I should add that I think the answer to the question will be no, a safe RPV can't be created for a SCWR.

Tuesday, May 10, 2011

Don't Ever Believe the Hype

Elsewhere at some point(s) since the start of the Fukushima Dai-ichi crisis, I have made statements indicating that the nuclear regulatory infrastructure of Japan and France were something this country should emulate.  I was wrong, and very wrong in the case of Japan.  Stoneleigh, one of the semi-pseudonymous proprietors of The Automatic Earth, a doomer-ish economy-oriented blog, has put together an excellent, detailed post on the culture of the Japanese nuclear industry.  It is not flattering.  And, in retrospect, it is not surprising, either.  Japan's yin-yang of cohesiveness and crushing conformity are well know, as are the troubles at the MONJU experimental sodium-cooled fast reactor.  Some of the other incidents I was not aware of, but I nonetheless should have been more cynical about Japan's nuclear industry.

As with Japan, the French nuclear industry doesn't look so wonderful when examined in detail.  Mycle Schneider, an independent consultant on nuclear policy, has authored a report entitled Nuclear Power in France: Beyond the Myth.  In it he details the opaque and undemocratic nature of the nuclear power establishment in France.  Fortunately for France and its neighbors, this has not resulted in a catastrophic accident like Fukushima, perhaps because the flip side of the arrogance of the elites that run the French program is in internal culture of technocratic excellence.  But the lack of clear information does make monitoring the program difficult.  The information deficit also makes an accurate tally of subsidies and costs impossible.  While I disagree with some of Schneider's energy accounting, he does make a good argument that EdF, the monopoly electricity generator, has overbuilt nuclear generating capacity.   This has distorted electricity pricing in France and neighboring countries.

If forced to pick between the two, given the available information, I would definitely choose the French nuclear power program over the Japanese one.  I would also choose the American program over the Japanese.  In a comparison between the American program and the French one, I think I would favor the French one... slightly.  The US is more open than France, but the profit motive drives the numerous operators to a far greater degree than in France, which has led to a number of close calls.  Ominously, the US regulatory structure is looking more and more like the Japanese one, with private companies able to dominate the relevant government agencies.  This is a disturbing development.  Of course, no regulatory framework is perfect, just as no nuclear plant is foolproof.  The technology requires constant vigilance.  The open question in the US is whether the NRC can re-assert itself to make sure safety is put before profit.

Sunday, May 8, 2011

Mo' Money, Mo' Money, Mo' Money

The NYT has a good article on the NRC up.  Here's a passage that I want to highlight:
In 2008, for example, workers at the Oconee plant in South Carolina discovered that a crucial line in the cooling system at Reactor Unit 1 was blocked by a broken gasket. The workers fixed it and the reactor was restarted.
But the two N.R.C. inspectors assigned full time to Oconee quickly began asking why Duke Energy, the operator, wasn’t also inspecting corresponding valves and lines at the plant’s other two reactors. Duke said the clogging was isolated and a blocked line could be bypassed in a pinch.
In February 2010, when the company finally agreed to look at the other two reactors, it discovered that the lines there had the same problem and that the bypass option would never have worked.
I think this is a good illustration of why the current ownership model of nuclear power plants is problematic.  In this situation, the NRC identified a safety issue in one reactor that could have been generic to all three of the B&W L-loop PWRs at Oconee Nuclear Station.  (It also could have been generic to all L-loop plants, of which there are seven operating.  Were the other four inspected?)  But the owner of the power plant successfully fought off inspection of the other two reactors for two years.

Why did Duke try to stop further inspections?  Because shutdowns might have been required (and ultimately were).  A reactor that is shut down doesn't make money, and making money is the sole purpose of private corporations in the US.  The senior management of a profitable company gets rewarded on a yearly basis, which is a much shorter time scale from when corner-cutting might result in an accident large or small.  But the impact of a large accident at a nuclear power plant is potentially very large, which means safety has to be pursued aggressively at all times.  That sets up a conflict between the plant owner/operator and the regulatory agency, and in today's (legally) corrupt politics, the regulator ends up backing down.