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MICHAEL SHORT: So as a quick review

of all the different biological effects,

we've pretty much taken it up to here.

We've explained the physical and chemical stages

of what happens when radiation interacts

with mostly bags of water with some solutes in them, better

known as organisms at dynamic equilibrium.

Everything from the sort of femptosecond level, ionization

of water almost certainly, because that's

most of what biological things are,

to the formation of many, many, many, many, many different

radiolysis byproducts eventually that end up as just a few

that we care about, the longer-lived radiolytic

byproducts that will then diffuse away

from the original damage cascades

and go on to eat something else, likely DNA or something

that you don't want to get oxidized or chemically changed.

We talked a little bit about radiolysis in reactors

and how you can actually measure it directly

which was only done really a few years ago which is pretty cool.

Just to remind you of this experiment,

there's a tiny high-pressure cell

of high-pressure, high-temperature water.

There is a foil sample with a very thin region and protons

firing through it, so that they both irradiate the sample

and induce radiolysis in the water at the same time.

And this way, you can test the effect of radiolysis

in the water here versus just plain, old, high-pressure,

high-temperature corrosion here.

And the results are pretty striking,

where you can clearly see the boundary where the proton

beam was as well as the increased thickness

of the oxide and corrosion layer formed when radiolysis

is turned on, so to speak.

We went through DNA damage, and we ended with pseudoscience.

So I want to bring up a couple--

no, we don't have time for that.

But we spent the last 15 minutes of class railing

against pseudoscience and making sure that you check your facts,

but we pointed out a number of things

wrong with some of the studies.

So aside from just that guy misreading everything

on that entire blog, of the studies that you felt

weren't very convincing, what do you remember about them?

Some of those studies were totally fine, but some of them

were not.

AUDIENCE: The ones with particularly small sample

sizes.

MICHAEL SHORT: That's what I was hoping someone would say.

Yeah, the case study of four women

who got breast cancer in the pocket

where they held their cell phones, four, right?

Or in a study of 29 humans, 11 of them got brain tumors here.

It's pretty easy to cherry pick small amounts of data.

I did want to say that just because radio frequency

photons aren't ionizing, doesn't mean they can't hurt you.

If you've ever-- no, no one's ever been inside a microwave.

I wonder if anyone's ever felt the effects

of an external microwave being by something like this,

the active denial system.

One of my favorite weapons ever, because it doesn't actually

permanently hurt anyone.

It just heats up the outer layer of your skin.

It fires these non-ionizing photons at RF frequency

and effectively makes you feel like you're on fire.

So if there's a whole mess of troops charging at you--

let's say at the DMZ from North and South Korea--

all you've got to do is turn on this thing,

and they all think they're on fire,

because their body is sending them signals that I'm on fire.

And then you turn it off, and they're OK.

So no loss of life, no permanent damage,

a lot of maybe psychological, but whatever,

you can't see that.

AUDIENCE: Active denial.

MICHAEL SHORT: Active denial system, great name for it,

isn't it?

Yeah, I think non-lethal weapons are really the way

of the future is just make it unpleasant to engage

in warfare, and people probably won't.

But then no one has to get hurt, which is nice.

But then onto the sources of data, because like Sarah said,

sample size is everything, especially when you're

trying to figure out, are small amounts of radiation

bad for you?

This simple question hasn't really

been answered suitably yet, and that's because, thank god,

we don't have enough people exposed

to small but measurable amounts of radiation

to draw meaningful conclusions from this data.

I think that's a good thing, is if we were certain about

whether small amounts of radiation,

like one millisieverts, could cause cancer,

then there would have been millions or billions of people

exposed, and so it's kind of a good thing that they weren't.

But the sources of this data, the first source

was radium dial workers, like you may have heard of,

the folks that would lick the paint brushes with glow

in the dark radium watches.

They ended up setting the first occupational limit for dose,

because they were the first large group

to be exposed to radiation in a controlled setting.

Things like uranium miners, radon breathers, better known

as us, but especially folks that smoke anything.

Medical diagnostics, so anyone that gets a medical procedure,

you can follow up with them to find out what's, let's

say, the extra incidence of cancer and figure

out, if you have a high-dose medical procedure,

does it induce secondary cancer down the line?

But like we said last time, down the line is the key here.

I'd take a whole bunch of radiation

now, if it was going to save my life now, and maybe

make it messed up in 20 years.

Because then you get 20 more years of life

or however long you get.

And then from accidents, survivors

of the atomic bombs, not just the folks at the epicenter,

but in the whole fallout regions and nearby, as well as

nearby nuclear accidents and the criticality events

like the demon core that you guys analyzed on the exam.

Luckily, there aren't a lot of those, either.

But they were pretty severe, the ones that got exposed.

And speaking of accidents, has anyone ever heard

of the Kyshtym disaster?

This is the third-worst nuclear accident

that we know of in history, after Chernobyl and Fukushima,

and worse than Three Mile Island,

because Three Mile Island was an almost accident.

There was some partial melting of the core.

There was almost no release of radioactivity.

And the definition of a nuclear accident in the public sense

is release of radioactivity.

There's actually two quantities that folks

in PRA, or Probabilistic Risk Analysis,

are most interested in.

Has anyone heard of these terms, CDF and LERF?

Core Damage Frequency and Large Early Release Frequency.

All the fancy probability fault trees and everything

goes into calculating the probability

that the core gets damaged.

So that could be an accident in one right.

Or the probability of a radioactivity release.

And that is an accident.

So if no one's ever heard of this,

there's a city in Russia--

I don't know why it says Russland, maybe came

from a different language--

called Kyshtym, where they had the Mayak

nuclear and reprocessing plant.

And there was a tank full of radioactive waste

that was exploded.

It was a chemical explosion, but full of strontium,

all sorts of other radionuclides that

blew up with about 100 tons worth of TNT,

and ended up contaminating a rather large area

with this plume called the--

I think it's called the East Chelyabinsk Radioactive Trace--

or the--

what is it?

The south-- South-something Urals Radioactive Trace.

And that area is still contaminated today,

because the disaster was covered up, or rather wasn't--

nothing was said.

These towns here, they didn't--

weren't actually towns back in 1957 when this happened.

They were just given designations,

like Chelyabinsk-40 or Chelyabinsk-65,

because the largest nearby city was Chelyabinsk,