You can't bring in a bunch of little generators and "hook them up". If you could, no one would use the gigantic generators which cost incredible sums just to transport.

ces, if you care, in the first few hours after the disaster I heard discussion, by informed TEPCO representatives, of shipping in generators, but it was dismissed because it was logistically impossible.

Realistically it'll be a long time away before we can get away from Coal. Until we do I wouldn't even consider trying to get away from Nuclear.

But there does seem to be this stigma associated with radioactivity. While watching footage of that refinery burn, I wondered how many carcinogens that put in the air. The reactor issues are troubling, but there is so much destruction there, any damage from radioactivity will probably wind up getting dwarfed by the scale of the deaths from the tsunami itself.

I believe m0002a made an important point on the 'losing face' issue by the Japanese TEPCO executives.
I suspect this played a major role in their clumsy response and unwillingness to ask for help early.
While the 'sepukku option' so dear to CES may not be a realistic solution for the TEPCO executives,
I believe they should be and I hope they will be prosecuted to the full extent of the Japanese law.

I am referring to the Fukushima I plant in the next lines, I believe it's the worst case.
The plant ran on backup batteries after the backup diesel generators were disabled by the tsunami.
These batteries maintained control functions and limited cooling for about 8 hours.
But the repair crews FAILED to connect portable generators within 8 hours, WHY?
Apparently they had backup to backup generators, but they couldn't connect them?

Now about an idea I had about providing emergency power to a nuclear plant, for the pumps which need a lot.
I believe a modified heavy-lift helicopter could be used as base for such a specialty device.
Setting a target of 10 MW of power (maybe less would be needed?), the Mi-26 with a special gear and
a generator could generate 10 MW when not flying - the power would go to the generator instead of the blades.
It has a maximum 17 MW of turbine power, and running the (old design) engines at 70% and a generator efficiency
of 90% would yield at least 10 MW of electrical power. The extra gear, generator and a lot of fuel should fit into the
20 tonnes of cargo specification of the Mi-26. If less than 10 MW of power is needed, a lesser helicopter will do.

WHY? Apparently they had backup to backup generators, but they couldn't connect them?

WHY? Apparently they had backup to backup generators, but they couldn't connect them?

The trouble, ces, with picking out heads to roll, is that that seems to satisfy the public. Whenever there is any kind of disaster, people are always looking to assign personal blame, even when the causality for the event is beyond the scope of any individual's actions. This placates the hordes calling for blood, but it usually results in only relatively shallow reforms being made when the situation could have been better handled by putting something in place that was deeper in concept.

Unfortunately the US Republican party leadership, along with their unwitting teabagger allies, has done such a good job of neutralizing any consequences to the financial industry in the US, there is almost certainly likely to be a repeat of similar (though not likely the same) financial harm to the American people in the US after we get a new generation of people in the industry (10 to 20 years), maybe even sooner if they can get a republican president elected in 2012.

I disagree with the cause and effect that you propose. Without heads rolling there will be no reform. The rolling of heads doesn't prevent reform. In many if not most situations it is a condition precedent to any meaningful reform.

You don't have to worry about heads rolling in Japan. The Japanese actually have a sense of responsibility to their country when they have done wrong, and a sense of personal responsibility for their actions. It is way too early to assess blame yet. But if anyone in Japan is found to have acted improperly during the nuclear plant crisis, they will voluntarily resign their positions (if they don't commit suicide first). But let's wait for some facts (instead of demagoguery) before that happens.

So what did the Democrats do to hold the financial industry accountable? Almost nothing, even though they had carte blanche to do whatever they wanted

As for the financial industry reforms in the U.S., that is indeed sad. That sector is so integrated with the government (Republicans more so than Democrats, it appears) that not only were no individuals punished, but few changes with any real lasting teeth were put in place.

As for the financial industry reforms in the U.S., that is indeed sad. That sector is so integrated with the government (Republicans more so than Democrats, it appears) that not only were no individuals punished, but few changes with any real lasting teeth were put in place.

Nuclear power is a very dangerous way to boil water

Advantages
- The reactor vessel and associated components operate at a substantially lower pressure (about 75 times atmospheric pressure) compared to a PWR (about 158 times atmospheric pressure).
- Pressure vessel is subject to significantly less irradiation compared to a PWR, and so does not become as brittle with age.
- Operates at a lower nuclear fuel temperature.
- Fewer components due to no steam generators and no pressurizer vessel. (Older BWRs have external recirculation loops, but even this piping is eliminated in modern BWRs, such as the ABWR.)
- Lower risk (probability) of a rupture causing loss of coolant compared to a PWR, and lower risk of core damage should such a rupture occur. This is due to fewer pipes, fewer large diameter pipes, fewer welds and no steam generator tubes.
- NRC assessments of limiting fault potentials indicate if such a fault occurred, the average BWR would be less likely to sustain core damage than the average PWR due to the robustness and redundancy of the Emergency Core Cooling System (ECCS).
- Unlike PWRs, BWRs have at least a few steam-turbine driven ECCS systems that can be directly operated by steam produced after a reactor shutdown, and require no electrical power. This results in less dependence on emergency diesel generators—of which there are four—in any event.
- Measuring the water level in the pressure vessel is the same for both normal and emergency operations, which results in easy and intuitive assessment of emergency conditions.
- Can operate at lower core power density levels using natural circulation without forced flow.
- A BWR may be designed to operate using only natural circulation so that recirculation pumps are eliminated entirely. (The new ESBWR design uses natural circulation.)
- BWRs do not use boric acid to control fission burn-up, leading to less possibility of corrosion within the reactor vessel and piping. (Corrosion from boric acid must be carefully monitored in PWRs; it has been demonstrated that reactor vessel head corrosion can occur if the reactor vessel head is not properly maintained. See Davis-Besse. Since BWRs do not utilize boric acid, these contingencies are eliminated.)
- BWRs generally have N-2 redundancy on their major safety-related systems, which normally consist of four "trains" of components. This generally means that up to two of the four components of a safety system can fail and the system will still perform if called upon.
- Due to their single major vendor (GE/Hitachi), the current fleet of BWRs have predictable, uniform designs that, while not completely standardized, generally are very similar to one another. The ABWR/ESBWR designs are completely standardized. Lack of standardization remains a problem with PWRs, as, at least in the United States, there are three design families represented among the current PWR fleet (Combustion Engineering, Westinghouse, and Babcock & Wilcox), within these families, there are quite divergent designs.
- Additional families of PWRs are being introduced. For example, Mitsubishi's APWR, Areva's US-EPR, and Westinghouse's AP1000/AP600 will add diversity and complexity to an already diverse crowd, and possibly cause customers seeking stability and predictability to seek other designs, such as the BWR.
- BWRs are overrepresented in imports, if the importing nation doesn't have a nuclear navy (PWRs are favored by nuclear naval states due to their compact, high-power design used on nuclear-powered vessels; since naval reactors are generally not exported, they cause national skill to be developed in PWR design, construction, and operation), or special national aspirations (special national aspirations lead to a marked preference for the CANDU reactor type due to special features of that type). This may be due to the fact that BWRs are ideally suited for peaceful uses like power generation, process/industrial/district heating, and desalinization, due to low cost, simplicity, and safety focus, which come at the expense of larger size and slightly lower thermal efficiency.
Sweden is standardized mainly on BWRs.
Germany has a large number of BWRs, which are overrepresented in their national fleet compared to the US.
Mexico's only two reactors are BWRs.
Japan experimented with both PWRs and BWRs, but most builds as of late have been of BWRs, specifically ABWRs.
In the CEGB open competition in the early 1960s for a standard design for UK 2nd-generation power reactors, the PWR didn't even make it to the final round, which was a showdown between the BWR (preferred for its easily understood design as well as for being predictable and "boring") and the AGCR, a uniquely British design; the indigenous design won, possibly on technical merits, possibly due to the proximity of a general election.
Disadvantages
- Complex calculations for managing consumption of nuclear fuel during operation due to "two phase (water and steam) fluid flow" in the upper part of the core. This requires more instrumentation in the reactor core. The innovation of computers, however, makes this less of an issue.
- Much larger pressure vessel than for a PWR of similar power, with correspondingly higher cost. (However, the overall cost is reduced because a modern BWR has no main steam generators and associated piping.)
- Contamination of the turbine by short-lived activation products. This means that shielding and access control around the steam turbine are required during normal operations due to the radiation levels arising from the steam entering directly from the reactor core. This is a moderately minor concern, as most of the radiation flux is due to Nitrogen-16, which has a half-life measured in seconds, allowing the turbine chamber to be entered into within minutes of shutdown.
- Though the present fleet of BWRs are said to be less likely to suffer core damage from the "1 in 100,000 reactor-year" limiting fault than the present fleet of PWRs are (due to increased ECCS robustness and redundancy) there have been concerns raised about the pressure containment ability of the as-built, unmodified Mark I containment – that such may be insufficient to contain pressures generated by a limiting fault combined with complete ECCS failure that results in extremely severe core damage. In this double failure scenario, assumed to be extremely unlikely prior to the Fukushima I nuclear accidents, an unmodified Mark I containment can allow some degree of radioactive release to occur. This is supposed to be mitigated by the modification of the Mark I containment; namely, the addition of an outgas stack system that, if containment pressure exceeds critical setpoints, is supposed to allow the orderly discharge of pressurizing gases after the gases pass through activated carbon filters designed to trap radionuclides[3].
- A BWR requires active cooling for a period of several hours to several days following shutdown, depending on its power history. Full insertion of BWRs control rods safely shuts down the primary nuclear reaction. However, radioactive decay of the fission products in the fuel will continue to actively generate decay heat at a gradually decreasing rate, requiring pumping of cooling water for an initial period to prevent overheating of the fuel. If active cooling fails during this post-shutdown period, the reactor can still overheat to a temperature high enough that zirconium in the fuel cladding will react with water and steam, producing hydrogen gas. In this event there is a high danger of hydrogen explosions, threatening structural damage to the reactor and/or associated safety systems and/or the exposure of highly radioactive spent fuel rods that may be stored in the reactor building (approx 15 tons of fuel is replenished each year to maintain normal BWR operation) as happened with the Fukushima I nuclear accidents.
- Control rods are inserted from below for current BWR designs. There are two available hydraulic power sources that can drive the control rods into the core for a BWR under emergency conditions. There is a dedicated high pressure hydraulic accumulator and also the pressure inside of the reactor pressure vessel available to each control rod. Either the dedicated accumulator (one per rod) or reactor pressure is capable of fully inserting each rod. Most other reactor types use top entry control rods that are held up in the withdrawn position by electromagnets, causing them to fall into the reactor by gravity if power is lost.

I do however doubt that the Japenese installations have the level of redundancy that BWRs elsewhere have.

You don't have to worry about heads rolling in Japan. The Japanese actually have a sense of responsibility to their country when they have done wrong, and a sense of personal responsibility for their actions. It is way too early to assess blame yet. But if anyone in Japan is found to have acted improperly during the nuclear plant crisis, they will voluntarily resign their positions (if they don't commit suicide first). But let's wait for some facts (instead of demagoguery) before that happens.

You may remember TEPCO got in trouble for falsifying test data around 10 years ago. The resulting investigation found false reporting was endemic for decades. Technicians were LITERALLY photocopying test data from other days and this included at Fukushima which was temporarily closed when the scandal came out.

They have also previously had numerous non-nuclear accidents involving ancillary plant that has not been correctly maintained or inspected and some workers have died in these accidents. I would not be confident in the state of their diesel generators and pumps given these issues.

Getting emergency power in has been made difficult because of the tsunami damage but no external resource should be being depended upon in such an instance anyway, that shows a lack of planning.

1. Dr. Michio Kaku on Japanese Reactor disaster on Mar 12, 2011 - fairly laid back with a thorough explanation of the situation
http://www.youtube.com/watch?v=ySPe0rQaPx4

It is an American joke

Boron is a good idea. Good enough that in the UK we were building boron bead injection systems into reactors at the same time that Fukushima was being built. This operates as a last line of defence in a Trip and writes off the reactor. Control rods and gas injection come before that.

Burying a reactor is a good approach to stopping it but is not a long term approach. With Chenobyl they used remote control bulldozers to pile earth and hurridly cast concrete blocks to assemble around the core however this exists entirely as a compression structure and rests on top of the damaged pressure vessel. The blocks are not held together at all and any internal collapse could result in a 2nd Chenobyl accident. To this end a permanent tomb is still being built.

In the case of Fukushima you would have to deal with the short term issues prior to entombment as otherwise you would have a big pile of sand sitting on top of a fragile structure that still had an out of control reaction in the middle of it.