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Environmental Impacts of Nuclear Technologies Bill Menke, October 19, 2005. Summary. 1 radioactivity measurment 2 Neutron chain reactions 3 Environmental Issues production storage use disposal. measurement.

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Environmental impacts of nuclear technologies bill menke october 19 2005 l.jpg
Environmental Impacts ofNuclear TechnologiesBill Menke, October 19, 2005


Summary l.jpg
Summary

1 radioactivity measurment

2 Neutron chain reactions

3 Environmental Issues

production

storage

use

disposal



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Radiation: energy-carrying particles (including light) spontaneously emitted by a radioactive atom


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Measuring Radiation spontaneously emitted by a

  • Assessing the radioactivity of a chunk of material. Activity: Count the number of disintegrations per second.

    • Becquerel (Bq): Activity expressed in disintegrations per second.

    • Curie (Ci): (An old unit) Activity expressed in equivalent grams of Radium. 1 Becquerel = 2.7 x 10-11 Curies.

  • Assessing the amount of energy absorbed by a chunk of material.

    • will depend upon both the number of particles and the energy carried by the particles emitted by the disintegrating atoms.

    • Grays (Gy), Absorption of 1 joule (J) of radiation by 1 kg of material (for example, a human body).

    • Rad (an old unit) 1 Gy = 100 rads

  • Assessing the ability of radiation to damage living tissue. Must account for the fact that not all types of radiation are equally damaging.

    • X-rays and beta particles more penetrating and more damaging than alphas or neutrons.

    • Sievert (Sv) = Grays of X-rays and beta rays + 0.10 Grays of neutrons + 0.05 Grays of alpha partcles.

    • Rem: (an old unit), 1 Sv = 100 rems.



Neutron chain reactions l.jpg
Neutron chain reactions spontaneously emitted by a


Fission of atomic nucleus by neutron bombardment l.jpg
fission of atomic nucleus spontaneously emitted by a by neutron bombardment


One neutron in three neutrons out potential for using those neutrons to induce more fissions l.jpg
one neutron in, three neutrons out spontaneously emitted by a potential for usingthose neutronsto induce more fissions


Leo szilard 1898 1964 l.jpg
Leo Szilard, 1898-1964 spontaneously emitted by a

1934: patents idea

of neutron chain

reaction

(British patent 440,023)

And nuclear reactor

(patent 630726)


More and more neutrons cause more and more fissions l.jpg
More and more neutrons spontaneously emitted by a cause more and more fissions


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I generated these images with spontaneously emitted by a the appletlectureonline.cl.msu.edu/~mmp/applist/chain/chain.htmtry it out!


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Technical Issue 1 spontaneously emitted by a

What isotopes of what elements exhibit induced fission and release

more neutrons? Only a few:

U235 + n = Ba129 + Kr93 + 3n + g

Note g = gamma rays

As well as Pu239, U233 and Th232

but only U235 and Pu239 commonly used


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Technical Issue 2 spontaneously emitted by a

Where do you get U235 and Pu239?

U235 occurs naturally, and is concentrated into ores by geological processes. But it must be separated from the much more abundant U238

by a process called gaseous diffusion separation).

Pu239 does not occur naturally, but can be

Manufactured by bombarding U238 with neutrons in a breeder reactor.


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Technical Issue 3 spontaneously emitted by a

Where do you get that first neutron?

Two sources:

natural, spontaneous decay releases it

(bad in a bomb!)

you make it in yet another nuclear reaction

(eg Po210 emits a which bombards Be to release n)


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Technical Issue 4 spontaneously emitted by a

Are the output neutron going the right speed to interact with more nuclei?

Perhaps not. You might have to slow them down by having them interact with a moderator. Deuterium, hydrogen, boron and graphite are all good moderators.


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Technical Issue 5 spontaneously emitted by a

What if too many neutrons escape from the surface of the fissionable material?

The chain-reaction ceases. This always happens if the piece of material is too small, below its critical mass. To prevent this, you can:

Surround the material with a reflector (e.g. Be)

Compress the material, to make it very dense.


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Technical Issue 6 spontaneously emitted by a

What if you want to control the rate of fission (e.g. reactor, not a bomb)?

You must absorb just enough neutrons so that the rate of fission is constant. These are the control rods in a reactor.


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Technical Issue 7 spontaneously emitted by a

What are the properties of the fission product, e.g. the Ba and Kr in

U235 + n = Ba129 + Kr93 + 3n + g

These are very radioactive, and their safe disposal presents a serious problem


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Technical Issue 8 spontaneously emitted by a

How do you get energy – kinetic energy and g - out of the chain reaction.

You let them interact with things and generate heat. Bomb: Heat builds up and everything vaporizes in an explosion. Reactor: remove heat steadily using cooling system.


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Technical Issue 9 spontaneously emitted by a

What happens when the neutrons interact with non-fissionable materials.

They can be absorbed, causing these materials to transmute into other isotopes, some of which are radioactive. E.g. cobalt, a trace element in steel:

Co59 + n = Co60

Co60 = Ni60 + b + g

(half life of CO60 is 5.27 years)


Environmental issues associated with nuclear fission l.jpg
Environmental Issues Associated with Nuclear Fission spontaneously emitted by a

Production

Storage

Use

Disposal


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Production of fissile materials spontaneously emitted by a

Production of fissile materials

Mining Uranium and Concentrating the Ore

Concentrating U235

Breeding Pu239


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Mining uranium spontaneously emitted by a

Key Lake mine, Saskatchewan, Canada


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Mining uranium spontaneously emitted by a

global distribution of uranium deposits


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What’s in the Ore ? spontaneously emitted by a

Ore can be up to 25% uranium oxide. The other 75%, in the form of ground up rock (tailings), needs to be disposed of.

Uranium is only mildly radioactive. But the ore contains significant Radon (a gas) and radium (a solid) that are more radioactive.


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Among uranium miners hired after 1950, whose all-cause Standardized mortality ratios was 1.5, 28 percent would experience premature death from lung diseases or injury in a lifetime of uranium mining. On average, each miner lost 1.5 yr of potential life due to mining-related lung cancer, or almost 3 months of life for each year employed in uranium mining.


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This wall of uranium tailings, visible behind the trees, is Standardized mortality ratios was 1.5, 28 percent would experience premature death from lung diseases or injury in a lifetime of uranium mining. On average, each miner lost 1.5 yr of potential life due to mining-related lung cancer, or almost 3 months of life for each year employed in uranium mining. radioactive waste from the Stanrock mill near Elliot Lake, Ontario.


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In 1975, St. Mary's School in Port Hope, Ontario, Canada was evacuated because of high radon levels in the cafeteria. It was soon learned that large volumes of radioactive wastes from uranium refining operations had been used as construction material in the school and all over town. Hundreds of buildings were found to be contaminated


Enriching uranium separating the u 235 from the u 238 l.jpg
Enriching uranium evacuated because of high radon levels in the cafeteria. It was soon learned that large volumes of radioactive wastes from uranium refining operations had been used as construction material in the school and all over town. Hundreds of buildings were found to be contaminated (separating the U235 from the U238)


Process uf 6 gas passed through a cascade of centrifuges l.jpg
Process: UF evacuated because of high radon levels in the cafeteria. It was soon learned that large volumes of radioactive wastes from uranium refining operations had been used as construction material in the school and all over town. Hundreds of buildings were found to be contaminated 6 gas passed througha cascade of centrifuges


Creating pu requires reactor l.jpg
Creating Pu: requires reactor evacuated because of high radon levels in the cafeteria. It was soon learned that large volumes of radioactive wastes from uranium refining operations had been used as construction material in the school and all over town. Hundreds of buildings were found to be contaminated

French Super Phenix Breeder Reactor


Then chemical separation of pu from reactor fuel l.jpg
then chemical separation of Pu from reactor fuel evacuated because of high radon levels in the cafeteria. It was soon learned that large volumes of radioactive wastes from uranium refining operations had been used as construction material in the school and all over town. Hundreds of buildings were found to be contaminated

Sellafield Plant (UK)


Legacy problems lots of leftovers from manhattan project and other military weapons projects l.jpg
Legacy problems – lots of leftovers evacuated because of high radon levels in the cafeteria. It was soon learned that large volumes of radioactive wastes from uranium refining operations had been used as construction material in the school and all over town. Hundreds of buildings were found to be contaminated from Manhattan Project and other military weapons projects


Problems l.jpg
Problems evacuated because of high radon levels in the cafeteria. It was soon learned that large volumes of radioactive wastes from uranium refining operations had been used as construction material in the school and all over town. Hundreds of buildings were found to be contaminated

  • Safely shipping of highly-radioactive spent reactor fuel to reprocessing plant

  • Accidental release of radioactive materials during chemical processing

  • Disposal of unwanted, but very radioactive by-products


Storage l.jpg
Storage evacuated because of high radon levels in the cafeteria. It was soon learned that large volumes of radioactive wastes from uranium refining operations had been used as construction material in the school and all over town. Hundreds of buildings were found to be contaminated

  • Here we focus mainly

    • Storage of weapons

    • Storage of spent nuclear fuel rods


Storage49 l.jpg
Storage evacuated because of high radon levels in the cafeteria. It was soon learned that large volumes of radioactive wastes from uranium refining operations had been used as construction material in the school and all over town. Hundreds of buildings were found to be contaminated

1997 Global Fissile Material Inventories (tonnes)

HEU = highly enriched uranium


Military stockpiles of pu by country tonnes l.jpg
Military stockpiles of Pu by country evacuated because of high radon levels in the cafeteria. It was soon learned that large volumes of radioactive wastes from uranium refining operations had been used as construction material in the school and all over town. Hundreds of buildings were found to be contaminated (tonnes)


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A 1 GW commercial reactor contains 75 tonnes of low-enriched uranium.About 1/3 of the fuel is replaced every 18 months.

Indian Point, about 35 miles north of Manhattan


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Current Storage at Indian Point uranium.

1500 tons spent fuel, stored immersed in “swimming pools” of water, where

Shrot-lived radionucleides decay away

Storage pool at a Canadian reactor



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Commericial Reactor Usage uranium.

About 20% of US

electricity generated

By nuclear plants


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