Fukushima 2 months on

[Russianwolf]

Again as a new nuclear plant supporter I learned many years ago to "never say never".

Is it possible for an accident the scale of Chornobyl to happen in the US today? Yes. Maybe not for identical causes, but to the same scale, yes.

Is that likely, no.

[Rand]

This is an interesting read about Chernobyl:

http://www.kiddofspeed.com/

[JimD]

I don't know how to deal with fear other than to offer facts. Did you know, for instance, that normally fossil plants emit more radiation than nuclear plants? There are traces of radioactive material in coal and they are released into the environment when the core is burned. Nuclear plants contain their radiation - normally. There are postulated health effects from the gases given off from burning fossil fuels. It is very possible people die from these effects too. The epa calculates deaths from poor air quality from our cars and fossil fuel burning. There just isn't a way to get the electricity our modern lives depend on without a risk to somebody. Many more coal miners die every year than have been directly killed by nuclear power.

This is a fairly good web site by the epa - decidedly not pro-nuclear - on the health effects of radiation:

http://www.epa.gov/radiation/underst...h_effects.html

This is an article saying low levels of exposure may be beneficial. This is not the assumption made when the health effects of Chernoybl are estimated to be above a few dozen people who worked in the plant during or after the incident:

http://www.21stcenturysciencetech.co...s/nuclear.html

This article pretty well summarizes the Chernoybl event and the various estimates of injuries. It is important, I think, in reading this to separate the studies of survivors from the estimates just made on the basis of estimated exposure and estimated health effect. The measurements of actual injuries in the populations are pretty modest except for thyroid cancer. That is pretty curable but also quite likely to be related to Chernoybl. Other cancers have been at normal rates, at least so far. Even in the most exposed population, the majority who were not killed quickly have not seen higher incidence of cancer. That seems to suggest a gross exageration of injuries by the mathamatical models. But I fully believe we should consider to study and things may change as these people age.

http://en.wikipedia.org/wiki/Chernobyl_disaster


But those of us who do not live near or work at a nuclear plant designed by Russia (and there is a range of Russian designs with many closer to Western plants) don't really have to worry about this kind of accident.

Jim

[MilDoc]

Let me put some of the facts re: Chernobyl simply:

1. The plant had no containment building to prevent radiation release in the event of an accident.

2. The reactor design was inherently unstable — in most reactors, when the cooling water overheats and turns to steam, power output drops; at Chernobyl, overheating water meant power rose. Not good, but not yet disastrous.

3. Then, one fateful April day, technicians purposely disabled the backup cooling system, removed most of the control rods, and switched off the power to the main cooling pumps to "see what would happen". Geez - just how stupid can you get.

What happened was that (well duh) the reactor overheated, power output shot up to a hundred times normal, and the lid blew off the core (with no containment), which then exploded again and caught fire. The exposed core burned for ten days.

Plus what has been mentioned re: graphite etc.

RE: our vast coal supplies. Each year, on average, 35 U.S. coal miners are killed and 4,000 are injured. Coal-burning power plants release close to three times as much radioactivity as nuclear plants. Not to mention noxious and global warming gases. gases.

We do need to have much better, independent backup systems, etc. NO plant should be built on fault lines etc. We need to have all reactors follow the same basic design. This allows a problem caught at one plant to be immediately be investigated at all other plants and steps taken to correct potential problems. [For those who know, is this the proposed nation wide plan for the A1000?] Off-site storage for worn fuel pellets should be normal.

What happened in Japan is somewhat reminiscent of New Orlean's hospitals. The backup generators were in the basement. Gee, you live below sea level, and you put the generators in the basement?

[JimD]

I am sure the company that markets AP1000s would love for there to be a nationwide plan but that isn't terribly American. Competition drives down prices and drives up innovation. But, as has been noted, especially for technology with significant inherent risk, there are also significant advantages to standardization.

Regardless of the design, any new nuclear plants built in this country will be built under new regulations that require a design to be approved up-front, before construction begins, and the operating license depends only on the plant being built consistent with the approved design. The operations permit is approved up-front subject only to successful inspections. This is to prevent the huge time delays on several previous generation plants waiting on their operating permit (Seabrook is often cited as an example). This process inherently increases standardization. So far, only AP1000 projects are under contruction but there are other approved designs.

Some interesting tidbits I heard yesterday, from somebody who may know a lot more about the incident because of his level in his company. The decision to use seawater cooling was made in Toyko. That is very wrong by American standards. Decisions on operation are to be made by operators. They get support from the rest of the company but are paid to make decisions. That resulted in a discussion of the inherent incompatibility fo the Japanese top down culture with nuclear safety culture. (I think that is at least partially resolvable with better procedures) The other tidbit is more speculative but the rumor is that Unit 4 lost 10 feet of water from it's spent fuel pit in the earthquake. It sloshed out. That makes sense relative to it uncovering fuel so quickly. The general belief in the discussion was that Units 5 and 6 will not operate again despite the fact that they are fine - undamaged. The further speculation is that Japan will be building some gas fired combustion turbines operating in a combined cycle and importing the gas from Russia. They need to do something to stop the rolling blackouts.

Jim

[leehljp]

. . . The decision to use seawater cooling was made in Toyko. That is very wrong by American standards. Decisions on operation are to be made by operators. They get support from the rest of the company but are paid to make decisions. That resulted in a discussion of the inherent incompatibility fo the Japanese top down culture with nuclear safety culture. (I think that is at least partially resolvable with better procedures)

Considering the weight and seriousness of that decision, That would be a major paradigm shift for their culture.

They need to do something to stop the rolling blackouts.
Jim

Our organization has an office near middle of Tokyo but recently moved to the outskirts of Tokyo in order to rent out the central Tokyo office building at a high rental rate. This rolling blackout has forced them to move back into the center of town. For those familiar, within the general area of the central loop line (Yamanote-sen) there is no rolling blackout. This is to make sure that the "government" and National broadcasting (NHK) can continue to function 24 hours.

For our organization, the problem is that being on the outskirts, the train/subway lines there are affected and some workers get caught in these blackouts and can't make it to work or back home for hours at a time. Most of the personnel are located closer to the center of town, so they would not be affected.

[LCHIEN]

standardization is also why we have several plants just like Fukushima Daiichi in the US right now.

But I agree that standardized reactor plans are a good idea overall, assuming the standardized design is excellent and there's ways to evolve improvements.

Picking the excellent design is always an issue, there's not a chance for the marketplace to work it out considering the time and costliness of each design, nor is trial and error evolution an option for Nuke plants. Committees tend to come up with compromises to satisfy differing opinions and philosphies so they aren't always the best.

Who annointed the AP1000 the best?

[Russianwolf]

standardization is also why we have several plants just like Fukushima Daiichi in the US right now.

But I agree that standardized reactor plans are a good idea overall, assuming the standardized design is excellent and there's ways to evolve improvements.

Picking the excellent design is always an issue, there's not a chance for the marketplace to work it out considering the time and costliness of each design, nor is trial and error evolution an option for Nuke plants. Committees tend to come up with compromises to satisfy differing opinions and philosphies so they aren't always the best.

Who annointed the AP1000 the best?

And there is no way that these private companies building them approach these designs with a "cost is no object" frame of mind.

[BobSch]

I'm not sure I'd have the guts these guys have

Retirees volunteer to work in plant.

http://www.dw-world.de/dw/article/0,...-asia-5133-rdf

[BigguyZ]

Retirees volunteer to work in plant.

http://www.dw-world.de/dw/article/0,...-asia-5133-rdf

That's pretty crazy. I'm sure you'd get a similar response here, but it's still cool to see people who are retired put the younger generation before themselves. That kind of selflessness is becoming more and more rare these days.

[Russianwolf]

That's pretty crazy. I'm sure you'd get a similar response here, but it's still cool to see people who are retired put the younger generation before themselves. That kind of selflessness is becoming more and more rare these days.

I did get a kick out of the article calling them middle-aged.

[BigguyZ]

Here's a question that I'm sure someone knows the answer to? What about breeder reactors? I've heard they use the spent fuel from the main reactors and reduce the amount of nuclear waste considerably. I also heard that the US doesn't allow for them, but France does.

How much of that is true/ correct? Are there negatives to using the breeder reactors?

[leehljp]

I did get a kick out of the article calling them middle-aged.

I was at a meeting last week in VA in which the 60's age group was referred to (in jest) as the "new middle age".

[MilDoc]

Question for those who know:

Reactor rods heat to 500+ degrees when uncovered, despite the graphite "scram" rods. Why?

Would one single rod in isolation also continue to radiate that high a temperature?

If so, just how is a nuclear plant refueled? Are the rods continuously cooled before and during insertion?

[LCHIEN]

Mildoc, my understanding is that fuel rods are warm because the the materials inside decay and release neutrons.

When in the presence of other fissile fuel rods the neutrons bombard other materials and cause more fission and emissions in a cascade to where more neutrons are being created in chain reactions.

Inserting graphite rods absorbs neutrons and slows the reactions down to simple decay rather than chain reactions.

After having been run the fuel rods have a number of fissile products created which have both long and short half lives... these continue to decay; the short half life stuff breaks down quickly but releases more heat (which is why the reactors need cooling after shut down).

After some time the rods are cooler but will always continue to emit heat.

At the end of their lives the "spent" fuel rods are removed but still contain a significant fraction of the original fissile material and this will also stay warm... that's why they keep them in the cooling ponds for 5 years. After 5 years they have decayed more and can be removed to dry storage casks which have air cooling but do not require water cooling. They will remain warm for a very long time...

I think The rods are removed with hoists at the top of the vessel after the reactor is shut down for a sufficient time to be in "cold shutdown". They'll still be hot but not so hot as to oxidize the zirconium housings.

look here:
http://www.nucleartourist.com/operation/refuel1.htm

they say BWR reactors are refueled every 12-14 months and replace about 25-40% of the rods each time. A rod may have a useful life of 3-5 years.
I imagine its a lengthy process.