How harmful is nuclear radiation? It depends on the dose received.

[Ludwik]

How harmful is nuclear radiation? It depends on the dose received.

 

Tsunami-related Fukushina accident will probably renew debates about nuclear electricity. Such debates should be based on what is known about negative effects of nuclear radiation. Numerical data below should be useful in that context.

 

The effect of penetrating radiation on a person depends on the dose received. The common unit of dose is Sievert (Sv). Smaller doses are expressed in milliseverts (mSv) or microseveret. The old unit of dose, rem, is also used widely (1Sv=100 rem)

 

A dose of 10 Sv will most likely results in death, within a day or two.

 

5 Sv would is kill about 50% of exposed people.

 

2 Sv can also be fatal, especially without prompt treatment.

 

 

0.25 Sv = 250 mSv is the limit for emergency workers in life-saving operations.

 

0.10 Sv = 100 mSv dose is clearly linked to later cancer risks.

 

0.05 Sv = 50 mSv is the yearly limit for for radiation workers.

 

 

0.004 Sv= 4 mSv typical yearly dose due to natural radiation (cosmic rays, etc).

 

0.003 Sv= 3 mSV typical dose from mammogram

 

The one day dose, due to Fukushima accident, at a distance of 30 miles from the damaged reactors, was reported (on 3/16 and 3/17) as 0.0036 mSv. I do not have data on doses, probably very large, received by those who worked near or inside reactors. But I have no doubt that each of them was carrying an individual dosimeter. No deaths due to radiation have been reported in Japan, as far as I know. Many lives, however, were lost in Chernobyl, by those who worked to minimize damage.

 

Ludwik Kowalski (see Wikipedia)

 

Professor Emeritus

 

Montclair State University, USA

[SMF]

A few days ago Bob Park's Whatsnew newsletter brought up hormesis as something that should be paid attention to relative to low dose ionizing radiation. Here is a Wikipedia link- http://en.wikipedia.org/wiki/Radiation_hormesis. What about this? SM

[ydoaPs]

[pippo]

How harmful is nuclear radiation? It depends on the dose received.

 

Tsunami-related Fukushina accident will probably renew debates about nuclear electricity. Such debates should be based on what is known about negative effects of nuclear radiation. Numerical data below should be useful in that context.

 

The effect of penetrating radiation on a person depends on the dose received. The common unit of dose is Sievert (Sv). Smaller doses are expressed in milliseverts (mSv) or microseveret. The old unit of dose, rem, is also used widely (1Sv=100 rem)

 

A dose of 10 Sv will most likely results in death, within a day or two.

 

5 Sv would is kill about 50% of exposed people.

 

2 Sv can also be fatal, especially without prompt treatment.

 

 

0.25 Sv = 250 mSv is the limit for emergency workers in life-saving operations.

 

0.10 Sv = 100 mSv dose is clearly linked to later cancer risks.

 

0.05 Sv = 50 mSv is the yearly limit for for radiation workers.

 

 

0.004 Sv= 4 mSv typical yearly dose due to natural radiation (cosmic rays, etc).

 

0.003 Sv= 3 mSV typical dose from mammogram

 

The one day dose, due to Fukushima accident, at a distance of 30 miles from the damaged reactors, was reported (on 3/16 and 3/17) as 0.0036 mSv. I do not have data on doses, probably very large, received by those who worked near or inside reactors. But I have no doubt that each of them was carrying an individual dosimeter. No deaths due to radiation have been reported in Japan, as far as I know. Many lives, however, were lost in Chernobyl, by those who worked to minimize damage.

 

Ludwik Kowalski (see Wikipedia)

 

Professor Emeritus

 

Montclair State University, USA

 

Professor,

 

Interesting for sure. You also may have stumbled across this but at Chernobyl, like you said, many people died- actually, it was close to or exactly 70 people (I didnt get that from today's AOL news/recent CNN reporting). But of course, that reactor was much different than what we had in 3 mile island=- it was cooled by graphite- much riskier setup.

 

Russians were bent on designing plants to also manufacture weapons grade Plutonium- unlike 3 mile island. The details I forget, other than that. nobody dies at 3 mile island, as you probably are aware of.

 

We'll see what happens to the nuke program- so much progress in recent years now this.........

Edited March 23, 2011 by pippo

[ydoaPs]

The Chernobyl incident wasn't as much about reactor design as much as it was improper operation. Many of the safety protocols were disabled.

[Mr Skeptic]

The Chernobyl incident wasn't as much about reactor design as much as it was improper operation. Many of the safety protocols were disabled.

 

Aren't the newer ones more retard-proof?

[ydoaPs]

Aren't the newer ones more retard-proof?

Yes, modern reactors are much more advanced, but you can still have significant problems should safety features be disabled. Consider the situation in Japan: even with a negative coefficient of reactivity due to temperature(which means a rise in temperature means a decrease in power) you can still have a meltdown if you don't get rid of the decay heat. Now, even with a meltdown, it's not too terrible so long as the reactor vessel isn't breached by a steam/hydrogen explosion or by the melted fuel itself. With nuclear incidents, containment and decay heat removal are pretty much everything. Contamination(spread of material that emits radiation) is a huge deal.

 

[math]D_2=D_1\frac{x_1}{x_2}[/math]

 

Where D₂ is the dose(amount of radiation you'd receive) you're trying to find at location x₂ and D₁ is the dose you know at location x₁. To see how dramatically the radiation decreases, let's use some easy numbers.

 

Let's assume that we know the dose D₁ at 1 foot away from the radiation source. We need to find the dose at 2 feet away from the radiation source.

 

[math]D_2=D_1\frac{x_1}{x_2}=D_1\frac{1}{2}[/math]

 

The radiation level already decreased by half! And that's ignoring the shielding effects of the atmosphere between the points.

 

If there is a meltdown and contamination is breached, it could send a lot of radioactive material airborne. Alpha particles and beta particles don't really do a whole lot of damage when they're on the outside of your body; they are both stopped by the layer of dead skin. However, if you inhale radioactive alpha and beta sources, then it's a bad day indeed.

[swansont]

Professor,

 

Interesting for sure. You also may have stumbled across this but at Chernobyl, like you said, many people died- actually, it was close to or exactly 70 people (I didnt get that from today's AOL news/recent CNN reporting). But of course, that reactor was much different than what we had in 3 mile island=- it was cooled by graphite- much riskier setup.

 

 

Chernobyl was cooled by water, but used graphite as a moderator.

 

The Chernobyl incident wasn't as much about reactor design as much as it was improper operation. Many of the safety protocols were disabled.

 

Some of column A and some of column B, I'd say. No containment building certainly didn't help, and the positive void coefficient of reactivity log with the ability to withdraw the control rods far enough to trigger that negative void coefficient when they were reinserted (during the scram) were arguably design flaws.

[pippo]

Chernobyl was cooled by water, but used graphite as a moderator.

 

 

 

May be so.....still, its no 3 mile island. nothing like it. They made no plutonium at 3 mile...

[swansont]

May be so.....still, its no 3 mile island. nothing like it. They made no plutonium at 3 mile...

 

Not sure how they would avoid making some plutonium. U-238 absorbs a neutron and becomes U-239, which beta decays to Np-239, which betas to Pu-239. The question is how much you make and how fast you use it up, since it's fissile.

[pippo]

Not sure how they would avoid making some plutonium. U-238 absorbs a neutron and becomes U-239, which beta decays to Np-239, which betas to Pu-239. The question is how much you make and how fast you use it up, since it's fissile.

 

Thanks, swan. Well, I am not a physicist, but that doesnt prevent /preclude us from having a discussion/opinions, I figure. I understand, (from a former DOE Secretary, oh, and theres also literature on this) chernobyl and 3 mile are like apples and oranges. You probably have a point in yes, nuclear generates plutonium, but the way I understood it, the big difference was WEAPONS grade plutonium. Also, the graphite being a key factor in the cooling mechanism, unlike 3 mile......

 

Chernobyl was really bad..............

Edited March 30, 2011 by pippo

[swansont]

Thanks, swan. Well, I am not a physicist, but that doesnt prevent /preclude us from having a discussion/opinions, I figure. I understand, (from a former DOE Secretary, oh, and theres also literature on this) chernobyl and 3 mile are like apples and oranges. You probably have a point in yes, nuclear generates plutonium, but the way I understood it, the big difference was WEAPONS grade plutonium. Also, the graphite being a key factor in the cooling mechanism, unlike 3 mile......

 

Graphite was the moderator, not the coolant.

Pu-239 is weapons-grade plutonium. The key is making it in quantity, i.e. it has to be produced faster than you lose it to fission, which to the best of my knowledge has to be by minimizing neutron losses (i.e. not sustaining criticality) to anything but absorption in U-239. You do this by using heavy water so you can use unenriched uranium as the fuel — that maximizes the fraction of U-238 in it.

 

Chernobyl was really bad..............

 

Yes, it was.

[pippo]

Graphite was the moderator, not the coolant.

Pu-239 is weapons-grade plutonium. The key is making it in quantity, i.e. it has to be produced faster than you lose it to fission, which to the best of my knowledge has to be by minimizing neutron losses (i.e. not sustaining criticality) to anything but absorption in U-239. You do this by using heavy water so you can use unenriched uranium as the fuel — that maximizes the fraction of U-238 in it.

 

 

 

Yes, it was.

 

Thanks, swan.....OK, moderator, not coolant. Still, it was the main difference in why Chernobyl was more serious than 3 mile, I understand. I learned something. Funny- thats how I remember the sec of Energy explaining it. I didnt confirm that though- just took it for scripture.

 

Still, I feel we shouldnt give up on nuclear, just cuz Japan.....oh well, we shall see....