Japan hit by 8.9 Magnitude Quake, Tsunami Warnings In Effect

[Craig P.]

Re: Japan hit by 8.9 Magnitude Quake, Tsunami Warnings In Effect

Everybody uses water, except the Russians, and Chernobyl made them wish they used water.

Huh? Chernobyl used water. It didn't make them wish they used water, it made them wish they didn't use a ****ty reactor design.

 

[Craig P.]

Re: Japan hit by 8.9 Magnitude Quake, Tsunami Warnings In Effect

Also, if they have been venting hydrogen gas, then they haven't reached the setpoints of the safety relief valves. And those are well below the Maximum Allowed Working Pressure the Rx vessel was designed for. So I doubt there was a steam explosion.

PSVs are typically set at the MAWP (with anywhere from 6% to 21% allowable overpressure in an event, depending on the design code and type of contingency). It is the maximum allowable <em>working</em> pressure, after all. The MAWP is intended to be below the failure pressure of the vessel by a substantial design margin, so you're right that any explosion would not have been within the pressure vessel.

 

[Craig P.]

Re: Japan hit by 8.9 Magnitude Quake, Tsunami Warnings In Effect

Again, Chernobyl was a completely different design. First, the control rods were graphite. When the core had a meltdown, the graphite caught fire. This exacerbated the problem. Eventually, this caused an explosion that was not contained because the reactor did not have the "last resort" containment vessel constructed of multiple feet of reinforced concrete.

The <em>moderator</em> was graphite. The control rods were something borated (though they had graphite tips, which was a serious design flaw because it meant that early in the insertion process, inserting the rods would increase rather than decrease the reaction rate, all the moreso given that it would displace water, which would poison the reaction albeit not as effectively as the control rod itself). The graphite burned after the explosions exposed it to atmosphere, but it was not involved in the explosions, which were initially a steam explosion and a secondary explosion the nature of which is still apparently a matter of debate (but, as I recall, graphite is not theorized to be one of the possible sources).

 

[Bakunin]

Re: Japan hit by 8.9 Magnitude Quake, Tsunami Warnings In Effect

The levels of radioactivity measured so far have barely exceeded the levels you get from a CT scan. Additionally, the measured levels of radioactivity do not necessarily mean the amount of radioactivity the body absorbs.

We're probably taking more radiation from the full body scanners at the airports than the Japanese are taking from the reactor problem.

 

[Kepler]

Re: Japan hit by 8.9 Magnitude Quake, Tsunami Warnings In Effect

The <em>moderator</em> was graphite. The control rods were something borated (though they had graphite tips, which was a serious design flaw because it meant that early in the insertion process, inserting the rods would increase rather than decrease the reaction rate, all the moreso given that it would displace water, which would poison the reaction albeit not as effectively as the control rod itself). The graphite burned after the explosions exposed it to atmosphere, but it was not involved in the explosions, which were initially a steam explosion and a secondary explosion the nature of which is still apparently a matter of debate (but, as I recall, graphite is not theorized to be one of the possible sources).

Craig, you obviously know what you're talking about. Could you recommend a resource for those of us who want to learn about nuclear reactors and nuclear power from the ground up, so to speak? Assume a fair number of working brain cells and a high school science background.

Self edit: this is good.

 

[Craig P.]

Re: Japan hit by 8.9 Magnitude Quake, Tsunami Warnings In Effect

Craig, you obviously know what you're talking about. Could you recommend a resource for those of us who want to learn about nuclear reactors and nuclear power from the ground up, so to speak? Assume a fair number of working brain cells and a high school science background.

Self edit: this is good.

What I know about nuclear power is what an intelligent person who learns quickly can get from various sources, particularly more in-depth articles on Chernobyl. (Wikipedia has an in-depth article at "Chernobyl disaster".)

The main thing to keep in mind about how the nuclear chain reaction proceeds is that neutrons have to be moving slowly enough to be captured by a fissionable nucleus in order to sustain the reaction. Otherwise, they'll just bounce off the nucleus, and I've read that neutrons have a relatively short half-life when they're not in a nucleus.

In order to slow the neutrons down, a nuclear reactor contains something they call a moderator. In the Japanese reactors, I believe the cooling water also acts as the moderator (which means that it has negative feedback in response to loss of coolant). In Chernobyl, they used graphite as a moderator with the cooling water acting as an additional control (absorbing neutrons), meaning that he had a positive feedback in response to loss of coolant (reduction in absorption by the water leading to increased absorption by the fuel, setting off a runaway reaction).

I think the link you posted covers the situation in Japan adequately.

 

[dxmnkd316]

Re: Japan hit by 8.9 Magnitude Quake, Tsunami Warnings In Effect

The <em>moderator</em> was graphite. The control rods were something borated (though they had graphite tips, which was a serious design flaw because it meant that early in the insertion process, inserting the rods would increase rather than decrease the reaction rate, all the moreso given that it would displace water, which would poison the reaction albeit not as effectively as the control rod itself). The graphite burned after the explosions exposed it to atmosphere, but it was not involved in the explosions, which were initially a steam explosion and a secondary explosion the nature of which is still apparently a matter of debate (but, as I recall, graphite is not theorized to be one of the possible sources).

See above for my correction. Had a brain fart. It happens.

 

[Twitch Boy]

Re: Japan hit by 8.9 Magnitude Quake, Tsunami Warnings In Effect

JFC, even Michigan is selling out of potassium iodide.

People are stupid.

For cripe's sake, my multivitamin has potassium iodide in it.

 

[huskyfan]

Re: Japan hit by 8.9 Magnitude Quake, Tsunami Warnings In Effect

new fire in reactor #4

 

[mookie1995]

Re: Japan hit by 8.9 Magnitude Quake, Tsunami Warnings In Effect

JFC, even Michigan is selling out of potassium iodide.

People are stupid.

For cripe's sake, my multivitamin has potassium iodide in it.

thyroid is very important!!!! it, ah... um... it's... uh.

 

[dxmnkd316]

Re: Japan hit by 8.9 Magnitude Quake, Tsunami Warnings In Effect

http://www.technologyreview.com/blog/energy/26524/

MIT blog entry about the subject.

 

[goldy_331]

Re: Japan hit by 8.9 Magnitude Quake, Tsunami Warnings In Effect

Huh? Chernobyl used water. It didn't make them wish they used water, it made them wish they didn't use a ****ty reactor design.

Chernobyl used water as coolant, not moderator. And no secondary containment. As the Russians of that era liked to say "Ukrainians are cheaper than concrete."

 

[huskyfan]

Re: Japan hit by 8.9 Magnitude Quake, Tsunami Warnings In Effect

basically this nuclear story all boils (sorry!) down to this : the TEPCo executives are not telling what they know and even if they did tell, no one seems real sure exactly what will happen.

very very sad.

 

[DrDemento]

Re: Japan hit by 8.9 Magnitude Quake, Tsunami Warnings In Effect

JFC, even Michigan is selling out of potassium iodide.

People are stupid.

For cripe's sake, my multivitamin has potassium iodide in it.

Although it is not my specialty-I had always been taught that taking Iodides for radiation were most important for young children and pregnant women. For anyone over 20 it may not be so important. Also it is only really effective just before radiation exposure or immediately after. Taking it too late may actually be worse than not taking it since it can 'lock' radioactivity into the thyroid in some way. It used to be thought that the radiation induced thyroid cancers take 10-20 years to develop but after Chernobyl it was found that in young children the tumors can appear in as little as 5 years. Usually however the tumors more often than not fall in the curable range(approximately 75%). I wish I had more knowledge about it but my training was many years ago.

 

[dxmnkd316]

Re: Japan hit by 8.9 Magnitude Quake, Tsunami Warnings In Effect

Makes sense. I did some reading about KI tonight. I think you're dead on with the timetable. Unless you basically flood your thyroid with the nonradioactive iodine before you're exposed, it's pointless. Not sure about the "locking" of the I-131 (wish I could do superscript here) though. Not saying you're right or wrong, I just have no idea.

 

[DrDemento]

Re: Japan hit by 8.9 Magnitude Quake, Tsunami Warnings In Effect

Makes sense. I did some reading about KI tonight. I think you're dead on with the timetable. Unless you basically flood your thyroid with the nonradioactive iodine before you're exposed, it's pointless. Not sure about the "locking" of the I-131 (wish I could do superscript here) though. Not saying you're right or wrong, I just have no idea.

The possibility that exogenous Iodide could keep more of the radioactive Iodine in the thyroid is from research done a long time ago. My medical school training was in the late 60's but I still think most believe it to be the case if the Iodide is taken too late. But as i mentioned-this is not my specialty. i would be more of an expert on the skin cancers that can develop.

Just as aside-we gave one of our cats a shot of I-131 3 weeks ago in an attempt to treat a hyperacitve thyroid (most like due to a benign adenoma). The nuclear regulatory commission has so many restrictions on this procedure is is unbelievable. The cat has to be maintained in a leaded room for 96 hours and boarded. All waste material must then be collected and held for 2 weeks before disposal. And she had to be isolated from small children and pregnant women for 2 weeks. Vets do the procedure but there are darn few of them who are willing to do it because of the stringent controls and requirements. When this same shot is given in a human case-the patient is sent home the same day and just told to flush the toilet twice each time (and warned to stay home for a few days).

 

[dxmnkd316]

Re: Japan hit by 8.9 Magnitude Quake, Tsunami Warnings In Effect

For the record, Rachel Maddow has put on an absolutely brilliant show stuffed to the gills with nuclear engineers, scientists, and actual research!!! 99% of the time, I can't stand her. Tonight? Awesome!

 

[leswp1]

Re: Japan hit by 8.9 Magnitude Quake, Tsunami Warnings In Effect

The possibility that exogenous Iodide could keep more of the radioactive Iodine in the thyroid is from research done a long time ago. My medical school training was in the late 60's but I still think most believe it to be the case if the Iodide is taken too late. But as i mentioned-this is not my specialty. i would be more of an expert on the skin cancers that can develop.

Just as aside-we gave one of our cats a shot of I-131 3 weeks ago in an attempt to treat a hyperacitve thyroid (most like due to a benign adenoma). The nuclear regulatory commission has so many restrictions on this procedure is is unbelievable. The cat has to be maintained in a leaded room for 96 hours and boarded. All waste material must then be collected and held for 2 weeks before disposal. And she had to be isolated from small children and pregnant women for 2 weeks. Vets do the procedure but there are darn few of them who are willing to do it because of the stringent controls and requirements. When this same shot is given in a human case-the patient is sent home the same day and just told to flush the toilet twice each time (and warned to stay home for a few days).

Why does this not surprise me?

 

[dxmnkd316]

Re: Japan hit by 8.9 Magnitude Quake, Tsunami Warnings In Effect

The cat has to be maintained in a leaded room for 96 hours and boarded.

So, what you're saying is, you didn't know if the cat's fate until you opened the box?

(terribly sorry if this is a sore sport, the physics joke was just there on a tee and I couldn't resist)

 

[Craig P.]

Re: Japan hit by 8.9 Magnitude Quake, Tsunami Warnings In Effect

Chernobyl used water as coolant, not moderator. And no secondary containment. As the Russians of that era liked to say "Ukrainians are cheaper than concrete."

I know that, but I didn't follow that it was what he was getting at. The implication as I read it was that Chernobyl didn't use water at all, which isn't true, but your distinction would make sense.