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Nuclear events taking place in Japan.

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Ash Small

Mon Apr 04 2011, 05:12PM

Registered Member #3414 Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245

Having watched in disbelief as one 'nuclear expert' after another was interviewed on TV yesterday, saying that pouring concrete into the tunnels under reactor two would stop the leaking radioactive cooling water, and then having to wait until today to see the reports that said it had been unsuccessful, as the water pouring out of the 8 inch crack had 'washed the wet concrete away', I'm not sure whether to laugh or cry.....

Patrick

Mon Apr 04 2011, 05:20PM

Registered Member #2431 Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639

I too noticed that the article did not mention "blue flash" and no other sources make that claim that i could find. as for the neutron "beam" if it can be detected from 1.5km this is a huge freakin problem, if true.

I wonder how this measurement was taken and how a strong nuetron beam at distance could be seperated from a weak neutron source/beam at close range. (not saying it cant/wasnt done.)

I see few details on equipment in these articles/news blurbs, ususally a so called expert shooting there mouth off. I am all for independent international monitoring of these reactors if for no other reason then to eliminate the idiocy of the TEPCO drip, drip, drip of inaccurate and late news.

Nicko

Mon Apr 04 2011, 07:51PM

Registered Member #1334 Joined: Tue Feb 19 2008, 04:37PM
Location: Nr. London, UK
Posts: 615

Proud Mary wrote ...

Nicko wrote ...

Proud Mary wrote ...

Cherenkov light is created as particles move faster than the speed of light in a certain medium.

The above sentence is a tad misleading - specifically, this is only the phase velocity component of a particle in a dielectric medium exceeding the phase velocity of light in that medium.

I wrote above: ÄŒerenkov radiation is produced when beta particles travel faster than the phase velocity of light in water.

My bad! I should have re-read the whole thread rather than the end of it

Proud Mary

Mon Apr 04 2011, 09:18PM

Registered Member #543 Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992

Patrick wrote ...

I too noticed that the article did not mention "blue flash" and no other sources make that claim that i could find. as for the neutron "beam" if it can be detected from 1.5km this is a huge freakin problem, if true.

I wonder how this measurement was taken and how a strong nuetron beam at distance could be seperated from a weak neutron source/beam at close range. (not saying it cant/wasnt done.)

I have only the haziest idea about neutrons, but wouldn't a neutron spectrometer at once identify the nuclear reaction from whence they came?

Patrick

Mon Apr 04 2011, 09:51PM

Registered Member #2431 Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639

Proud Mary wrote ...

I have only the haziest idea about neutrons, but wouldn't a neutron spectrometer at once identify the nuclear reaction from whence they came?

I am still trying to figure that out, if I remember from research I did years ago, the neutrons were way more dificult to detect then ionizing emissions, as far as detector material goes. But as for identifying neutorn source, my brain is still thinking on that one, im still thinking at long range (beyond dozens of meters) spectroscopy may lose much usefulness, but this is beyond my general body of knowledge, so maybe im wrong. ill need to consult with some others on campus.

I just find that if it is detectable across 1,500 meters of atmosphere and somewhat directional, stunning.

EDIT:

if it isas little as 0.01-0.02uSv/hour then maybe this isnt so bad, but given TEPCO's past with facts and truth, well I dont know. Im just glad its not my body and limbs in the path of a flickering neutron source.

Note that some are saying this and other articles may have been mis-translated and it just means "neutron radiation detected at 1500 meters." and the "beam" part may be in error. A scintilator may be how there detecting a emission in the 0.01uSv non-ionizing quantity and still be able to seperate that from 200mSv of wild ionizing radiation plumes already present. still researching this though,.

Chris Russell

Mon Apr 04 2011, 10:29PM

... not Russel!
Registered Member #1 Joined: Thu Jan 26 2006, 12:18AM
Location: Tempe, Arizona
Posts: 1052

Patrick wrote ...

I just find that if it is detectable across 1,500 meters of atmosphere and somewhat directional, stunning.

The density of air at sea level is 1.1644 kg per cubic meter at sea level, 30C. So the neutron beam has to penetrate about 1750kg of shielding per square meter. This is approximately equivalent to penetrating 0.73 meters of concrete. Of course, we're talking about neutrons, not gamma rays, so it's not just a question of mass. That aside, though, it would seem to indicate they are detecting some rather energetic neutrons.

Patrick

Mon Apr 04 2011, 10:37PM

Registered Member #2431 Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639

Chris Russell wrote ...

Patrick wrote ...

I just find that if it is detectable across 1,500 meters of atmosphere and somewhat directional, stunning.

Yes I realize the air doesnt shield particularly well, but even if the supposed "beam" diverges only a little, then at 1,500 meters there should be much less that 1 meter, however neutrons are more effected by physical properties of materials too, and with a half life of about 15 mins or less.

[My brain is contemplating things now.]

I am also thinking if they aimed this detector at a pipe/hole opening into the reactor then this may be no big deal, indeed expected.

Proud Mary

Tue Apr 05 2011, 12:09AM

Registered Member #543 Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992

Perhaps water vapour in the air would shorten the neutron path somewhat. The site is beside the sea, and the land and the industrial ruins remaining on it are running with water, suggesting high relative humidity.

Patrick

Tue Apr 05 2011, 12:46AM

Registered Member #2431 Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639

Proud Mary wrote ...

Perhaps water vapour in the air would shorten the neutron path somewhat. The site is beside the sea, and the land and the industrial ruins remaining on it are running with water, suggesting high relative humidity.

Yes, thats a possibility, however we need to know two things to evaluate neutron emission, quantity and energy.
The supposed "0.01~0.02 uSv/Hr @1.5km" doesnt really tell us much, after 1500 meters there would be significant attentuation.

I must say I am relieved at this value, but if all the sudden TEPCO says 12 days later : "Oh wait we meant 1Sv/min, sorry. Move along everything is fine here." I will be so pissed off. I am so skeptical of the TEPCO reported info at this point.

I wonder if they were looking directly into a broken off pipe stub or whatever and maybe the reactor has flickered back to criticality (criticality localized to damaged parts of the reactor) 13 times, thus the measurement.

Ash Small

Tue Apr 05 2011, 01:45AM

Registered Member #3414 Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245

Neutrons don't just travel in one direction, they travel in all directions.

Maybe someone here can do the maths?

estimate the surface area of the detector, work out the surface area of a sphere 1.5 kM radius, and calculate the actual number of neutrons released per hour.

(This sounds like the previous figures released are for gamma radiation only)

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