Jet streams could carry radioactivity from Japan to the US

towards the US.

ers-b...

The numbers on the wiki pgae I'm lookng at say 450 mG of K and 53 micro-grams of K40.

George H.

ide quoted text -

Speaking of reactor waste, have I already posted this link?

Thanks, Rich

It has always seemed to me that it's stupid to bury long- term dangerous waste in a layer of stuff that is plastic, soluble and corrosive. I think the real reason they want to store waste in salt mines is that it is cheap to dig holes in salt.

Jeroen Belleman

Unfortunately, where fuel cycle radionucleides are concerned the average radiation level doesn't really hack it. If it really is a smooth average dose then fair enough but if there is particulate alpha emitting material in the smoke then as hotspots in the lungs it can do a great deal of harm. Sheep in parts of Wales are still not safe to eat because of Chernobyl it turns out highland plants and moss sequester caesium and it stays biologically available for a very long time.

We can already measure to sub ppq for most inorganic species (provided that the solvent is pure enough) and important organic ones. How else do you think they make modern semiconductors and the processing reagents? I helped a group in Japan that first pushed the detection limits beyond ppq (10^-15) in the 1990's and had to apply to IUPAC for a novel designation for the next scale down 10^18. The standard pattern breaks down because parts per quadrillion has already used ppq so the quintillion was poorly named. No-one expected it to be a problem.

Today some measurements are routinely done sub to ppq detection limits. You need the right kit and it isn't cheap but it is routine now. It was bleeding edge in the 1990's. There are even lab services that will do it for you with a periodic table of detection limits (for a price):

They are not prepared to handle radionucleides. The kit will but you need a much more expensive glove box version to handle open sources.

We were banned from demonstrating uranium and lead in tapwater to VIPs after a customer (the local water company) complained about it.

It is amusing to note that older adults are generally not fit for human consumption due to accumulated doses of organochlorines DDT etc.

Regards, Martin Brown

How much lead was released into the soil by the ruined cars' batteries?

l.

ove 10.

"Idiocracy"

-- Cheers, James Arthur

towards the US.

Naaaah! LA Basin, so the next big one plus tsunami will carry it out to sea :-) ...Jim Thompson

towards the US.

FWIW--

They don't like the way your teeth look. ;-)

Shouldn't that be "pushed in"? AIUI pulling the control rods allows the neutrons to sustain the reaction? Or is my info too old?

the US.

Reasonably managed nuclear power is safe. Coal mines kill more people, and coal plants put more radiation into the air, than nukes do. Oil rig workers die every year. The TMI meltdown was stupid and expensive, but didn't kill anyone.

Energy is dangerous.

Putting a nuke at sea level, in a tsunami zone, is sort of crazy. A

Note we

Used fuel rods should be reprocessed into new fuel rods. That would burn more isotopes and make more energy, and greatly reduce the volume of stuff that has to be sequestered for 100K years or whatever.

The US won't do this for illogical reasons.

John

allows

It's been a while since I took a nuclear course, but for Uranium you have to slow the neutrons down so they can be absorbed. I thought that was the control rods job. They 'moderate' the neutrons, so they can be absorbed by the next Uranium atom they run into. But I very well could have my terms mixed up.

George H.

towards the US.

" The US won't do this for illogical reasons."

Becasue the public is terrified of anything nuclear. The medical community got rid of the N in NMR, and we're stuck with MRI.

Of course the expense of a new nuclear power plant today is what makes it impractical.

George H.

No, you're correct. Even the original Chicago Pile was constructed so that removing neutron-absorbing control rods would add reactivity to the core (fewer neutrons absorbed -> more fissions).

I do seem to recall some designs (or at least Gedankenexperiments) where some control rods acted as neutron moderators rather than absorbers, so that inserting those rods would add reactivity by increasing the thermal neutron flux in their vicinity.

It is the newly formed and hot daughter fragments of uranium fission which are excessively neutron rich and have to sort themselves out by radioactive decay. The first few decay steps are fairly energetic and moderately fast with half lives mostly of hours and days. A rough rule of thumb for fallout after the first hour is that for every 7x increase in time the fallout level decays by a factor of 10. This crude rule doesn't apply when the reactor is still leaking fresh hot material.

You are correct. In the earliest designs the control rods were arranged so that they would passively gravity feed and there was a guy employed to scram the reactor if anything ever went wrong.

He was apocrophally designated the Safety Control Rod Axe Man. Hence to SCRAM a reactor for an emergency shutdown.

Slowing the thermal neutrons down is the job of the moderator which in the first generation were graphite cores and D2O has been used. Modern designs can use light water.

Control rods contain powerful neutron absorbers like boron and take the reactor gain down breaking the sustainability of the fission reaction.

Regards, Martin Brown

Is this the same "event" shown on NHK English broadcast.

The cabinet minister reported 400 mSv/hr, but the specialists present on the same press conference said in a polite way that the minister had mixed millisieverts and microsieverts.

The specialist then listed measurements in the 0.4-6 mSv/hr range. Thus, at least this "400 mSv/hr" reading is not very plausible.

And most news anchors are cluelessly leaving out the "/hr" part, rendering the measurement meaningless.

m?

rods allows

Thanks Martin, I figured someone could straighten it out. Doesn't Cadmium like to 'suck up' neutrons too?

George H.

I do not know about the GE PWR reactor designs used in Japan, but at least the ASEA Atom PWRs have the control rod mechanism below the core and in order to perform a SCRAM (shutdown) the control rods are actually shout into the core from below with pneumatics.

This might cause some ambiguity in terminology.

Correction: The plants that have problems in Japan are all Boiling Water Reactors (BWR) built by GE or licensed by Toshiba and Hitachi.

The Asea Atom constructions are also BWRs.

d towards the US.

Because they are doing it all wrong. Huge nuclear plants are unfixable/unmovable. Nuclear submarines are easily lost at sea. However, I wouldn't mine driving a nuclear automobile, as long as someone would handle decommissioning it.