Tuesday, March 15, 2011

Capacity Focus, 5: Japan -- from earthquakes and tsunamis to nuclear emergencies; significance for us

A few weeks ago, after months of meaning to discuss the matter, I raised the issue in this blog of passive-safe nuclear energy technologies as an option for the Caribbean (based on pebble bed and molten salt Thorium reactors). 

I did not anticipate how timely that first post in this series would be.

But the unfolding tragedy in Japan (cf earlier remarks here) has now put nuclear energy technologies and safety issues into the centre of focus.And, though I am busy with several other issues on and offline and have just got back DSL access overnight after my net access went down on the weekend due to an upgrade by the phone company, I have been approached [as a physicist] to comment on the situation.

I also think nuclear energy sufficiently important in developing a sustainable and desirable future that does not look like a modified version of C19 [which would imply a population collapse of several billions . . . ] that we need some background on it and on the specific concerns and balances of risks and hazards.

Russia Today has a useful round up news video from a couple of days back, that bridges from the earlier quake-tsunami story to the developing nuclear crisis at Fukushima No 1 and other sites that has apparently cost Japan ~ 20% or so of its [CORRECTION: nuclear] electricity generating capacity -- this will have severe economic impact there and globally -- quite well:

It is also worth excerpting the lead to the Wikipedia article on the disaster, as it provides a "crowd-source" news summary that is actually excellent:



>>The 2011 Sendai earthquake and tsunami (東北地方太平洋沖地震 Tōhoku Chihō Taiheiyō-oki Jishin[8]?, literally "Tōhoku region Pacific Ocean offshore earthquake"[FN 1])a 9.0 MW megathrust earthquake off the coast of Japan that occurred at 14:46 JST (05:46 UTC) on Friday 11 March 2011.[2][3][5][11][12] The epicenter was reported to be 130 kilometers (81 mi) off the east coast of the Oshika Peninsula, Tōhoku, with the hypocenter at a depth of 32 km (20 mi).[13][14] 

The earthquake triggered tsunami warnings and evacuations along Japan's Pacific coast and in at least 20 countries, including the entire Pacific coast of North America and South America.[15][16][17] The earthquake created extremely destructive tsunami waves of up to 10 meters (33 ft) that struck Japan minutes after the quake, in some cases travelling up to 10 km (6 mi) inland,[18] with smaller waves after several hours in many other countries.[12]

The Japanese National Police Agency has officially confirmed 3,373[6][7] deaths, 1,897[6][7] injuries, and 6,746[6][7] people missing across sixteen prefectures, but estimated numbers are far higher, ranging from thousands to tens of thousands dead or missing.[19] 

The earthquake and tsunami caused extensive and severe damage in Japan, including heavy damage to roads and railways as well as fires in many areas, and a dam collapse. Around 4.4 million households in northeastern Japan were left without electricity and 1.4 million without water.[20] Many electrical generators were taken down, and at least three nuclear reactors partially melted down,[21][22] which prompted evacuations of the affected areas,[23] and a state of emergency was established. Three reactors believed to have partially melted down have experienced a chemical explosion extensively damaging their buildings, and the integrity of the inner core-containment vessel of one compromised and some dangerously radioactive release from the plant has occurred.[20][24][25] Residents within a 20 km (12 mi) radius of the Fukushima I Nuclear Power Plant and a 10 km (6.2 mi) radius of the Fukushima II Nuclear Power Plant were evacuated. Early estimates from AIR Worldwide place insured losses from the earthquake and tsunami at US$14.5 to $34.6 billion.[26] Chief economist for Japan at Credit Suisse, Hiromichi Shirakawa, said in a note to clients that the estimated economic loss may be around $171–183 billion[27] just to the region which was hit by the quake and tsunami. The Bank of Japan offered a combined ¥15 trillion (US$183 billion) to the banking system on 14 March 2011[27] to normalize market conditions.

The estimates of the Sendai earthquake's magnitude made it the strongest known earthquake to hit Japan, and the fourth strongest earthquake in the world overall since modern record-keeping began in 1900.[28][29][30] Japanese Prime Minister Naoto Kan said that "in the 65 years after the end of World War II, this is the toughest and the most difficult crisis for Japan."[31] The earthquake moved Honshu 2.4 m (7.9 ft) east and shifted the Earth on its axis by almost 10 cm (3.9 in).[32] [NB: We so often have occasion to criticise the problems at Wikipedia, that when it does a good job like this, it is doubly important to say so, and use that in rating how and where sources like Wikipedia can be useful.]>>

A quake that moves the entire island of Honshu -- comparable to Cuba, say -- bodily by nearly eight feet and shifts the earth's axis of rotation four inches, is not to be underestimated. Neither are telephone-pole high walls of water moving up to six miles inland, at perhaps 30 miles per hour.

However, the nuclear disaster at Fukushima is the emerging focus of global attention, and it is where we need to now turn. 

Fukushima No 1, with reactor buildings 4, 3, 2, 1 in the left middle of the picture:

Josef Oehmen has written an excellent summary, now hosted by MIT's Nuclear Engineering Dept. Excerpting:
The plants at Fukushima are Boiling Water Reactors (BWR for short). A BWR produces electricity by boiling water, and spinning a a turbine with that steam. The nuclear fuel heats water, the water boils and creates steam, the steam then drives turbines that create the electricity, and the steam is then cooled and condensed back to water, and the water returns to be heated by the nuclear fuel.
The reactor operates at about 285 °C.
The nuclear fuel is uranium oxide. Uranium oxide is a ceramic with a very high melting point of about 2800 °C. The fuel is manufactured in pellets (cylinders that are about 1 cm tall and 1 com in diameter). These pellets are then put into a long tube made of Zircaloy (an alloy of zirconium) with a failure temperature of 1200 °C (caused by the auto-catalytic oxidation of water), and sealed tight. This tube is called a fuel rod. These fuel rods are then put together to form assemblies, of which several hundred make up the reactor core.
The solid fuel pellet (a ceramic oxide matrix) is the first barrier that retains many of the radioactive fission products produced by the fission process.  The Zircaloy casing is the second barrier to release that separates the radioactive fuel from the rest of the reactor.
The core is then placed in the pressure vessel . . . designed to withstand the high pressures that may occur during an accident. The pressure vessel is the third barrier to radioactive material release.
The entire primary loop of the nuclear reactor – the pressure vessel, pipes, and pumps that contain the coolant (water) – are housed in the containment structure.  This structure is the fourth barrier to radioactive material release . . . The containment structure is a hermetically (air tight) sealed, very thick structure made of steel and concrete. This structure is designed, built and tested for one single purpose: To contain, indefinitely, a complete core meltdown . . .
David C. Synnott/Katana0182 at Wikipedia has provided a helpful illustration, under CCA:

Oehmen summarises what went wrong:
The earthquake that hit Japan was [about five] times more powerful than the worst earthquake the nuclear power plant was built for [8.2 vs 8.9]  . . . .

 Within seconds after the earthquake started, the control rods had [automatically] been inserted into the core and the nuclear chain reaction stopped. At this point, the cooling system has to carry away the residual heat, about 7% of the full power heat load under normal operating conditions.
The earthquake destroyed the external power supply of the nuclear reactor . . . For the first hour, the first set of multiple emergency diesel power generators started and provided the electricity that was needed. However, when the tsunami arrived (a very rare and larger than anticipated tsunami) it flooded the diesel generators, causing them to fail . . . . the reactor operators switched to emergency battery power . . . .

After 8 hours, the batteries ran out, and the residual heat could not be carried away any more.  At this point the plant operators begin to follow emergency procedures that are in place for a “loss of cooling event” . . . . 
[M]obile generators were transported to the site and some power was restored . . . . more water was boiling off and being vented than was being added to the reactor, thus decreasing the cooling ability of the remaining cooling systems. At some stage during this venting process, the water level may have dropped below the top of the fuel rods.  Regardless, the temperature of some of the fuel rod cladding exceeded 1200 °C, initiating a reaction between the Zircaloy and water. This oxidizing reaction produces hydrogen gas, which mixes with the gas-steam mixture being vented.
Very hot hydrogen gas hitting the atmosphere triggered explosions, and these have done more damage, and as was summarised by Wikipedia, there has apparently been some "meltdown." As a part of all of this, some radioactive materials have been vented, and some have apparently been released by/due to the explosive events. Evacuations have been ordered, and Japan is facing loss of some 20% of its [correction: NUCLEAR] power generation capacity. For the number 2 or 3 economy in the world, as China seems to have just overtaken.

The quickest restoration of some capacity is oil and natural gas fired plants, which will put further pressure on global fossil fuel supplies and refinery capacity. In addition, plans to build more nuke plants all around the world probably just went on hold. That is, blending in the already dangerous instabilities in the Middle East, we can expect sharpish rises in energy prices in coming weeks and months.

All of this immediately implies a further round of price rises in fuels, including gasoline and diesel; further putting pressure on economies. And, since the cost of food is strongly driven by energy prices, food and other prices -- predictably -- are going to go up again. (This, on top of the threatening situation with Iran in the Middle East, and the wave of uprisings and protests across that always turbulent zone.)

None of this is good news for the Caribbean in a time of already harsh economic difficulties.

But, we must brace for it.

In addition, the events underscore the issues of risk/crisis management and disaster mitigation. The Japanese plainly planned for worst reasonable cases, but their defences in depth were overwhelmed by a much bigger disaster than they planned for. They have been reduced to pouring seawater into the reactors and adding boric acid to ensure the nuclear reaction is damped down. I suspect, that is going to add to damages, and will stretch out recovery times for reactors that will be recoverable.

Already, people are reacting to a nuclear accident. But, we must put this in context: global dependence on oil has meant arming radicals and other unstable regimes in the Middle East, it has forced the expenditure of trillions over the years on entire naval fleets, and is tied to all the questions on fossil fuel dependency and environmental as well as economic impacts.  Most renewables are unreliable and not available in relevant quantities on economic terms. The big exception, hydro, is very site dependent, and requires massive dams and inundations of large swaths of land, with their own environmental impacts.

And, in places like Montserrat, Nevis, Dominica, St Lucia etc, where geothermal energy is a possibility, that needs to be explored as economic development priority number one.

For, one thing is certain: oil fuel technology is simply not a long term economically sustainable basis for electrical energy, in an era where stable, reliable, economically affordable electricity is a prime basis for economic survival, much less prosperity.

That means our region -- not just policy wonks, politicians and Electric Utility managers and engineers, EVERYBODY --  needs to think through the options and possibilities, balancing risks of each major energy and development alternative, very carefully. Then, we need to build and act on a sound consensus on ways to a sustainable energy future, with a balance of technologies that we can afford, and that can sustain a viable economic base for a thriving region.

One thing is certain: there are no easy options or magic cures, only intelligent, prudent choices on trade-offs and balances of risks. END


F/N: Daily Mail has an excellent summary here, with pictures and diagrams with explanations. For example:

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