Biological Effects of Ionizing Radiationsrjcstaff.santarosa.edu/~lwillia2/lovon43/43ch45_s12.pdf ·...

Biological Effects of Ionizing Radiation

Radiation Dose "Dose" the amount of radioactive energy that is actually absorbed

by tissues in the body. Radiation dose unit (rad) : 1 r = 0.01 J/kg

Roentgen Equivalent Man: rem = rad x RBE

The biological effect depends on the type of radiation and body part: RBE: Relative biological effectiveness

Type of energy of radiation RBE X rays 1 Gamma rays 1 Beta rays > 30KeV 1 Beta rays < 30 KeV 1.7 Neutrons, slow 2-5 Neutrons, fast 10 (body) 30 (eyes) Alpha Rays 10-20

Other Units 1 Gray (Gy) = 1 J/kg = 100 rad 1 sievert (Sv) = 100 rem The unit of activity is the curie (Ci) 1 Ci ≡ 3.7 x 1010 decays/s (Bq)

50% mortality rate About 50% of the people exposed to a dose of 400 to 500 rem will die

Background Radiation: ~300 mrem/year •Sources are UV radiation and cosmic particles, radium, radon, potassium 40, carbon 12 present in rocks, air, and our own body cells. •Exposure to Natural Radiation induced mutations may have contributed to our evolutionary process. Most geneticists believe that humanity has reached an evolutionary peak in beneficial mutations caused by natural radiation that the species can undergo. Thus any further mutations are detrimental, causing disease and deformity.

•Although the exact percent is unknown, background radiation is thought to be responsible for a portion of all cancers and genetic disorders.

Radiation Levels • Natural sources – rocks and soil, cosmic

rays – Called background radiation – About 0.13 rem/yr

• Upper limit suggested by US government – 0.50 rem/yr – Excludes background

• Occupational – 5 rem/yr for whole-body radiation – Certain body parts can withstand higher levels – Ingestion or inhalation is most dangerous

Plutonium-239 decays by alpha emission with energy 6.02 MeV. If you inhale 1 milligram of plutonium and it effects 1.00 kg of your lung, what would be your dose in one day in rem if 50% of the energy is absorbed? What biological effect would that have on your body? Assume the lowest RBE for alpha particles.

energy #decays x Energy/decaydose = mass effected mass of lung

=

1 2 1 2

0.693 0.693# AN Ndecays Activity A N mt t M

λ= = = = =

-3 23 619

4

.693(10 )(6.022 10 / )6.02 10 /dose = (.5) (1.6 10 / )2.41x10 (239.0522 / )(1 )

g x mol x eV decay x J eVyr g mol kg

−

dose = 34.9 /J kg yr⋅

Sample Problem

1dose(rad) = 34.9 / ( ) 3490 /.01 /

radJ kg yr rad yearJ kg

⋅ =

Plutonium-239 decays by alpha emission with energy 6.02 MeV. If you inhale 1milligram of plutonium and it effects 1.00 kg of your lung, what would be your dose one day in rem if 50% of the energy is absorbed? What biological effect would that have on your body? Assume the lowest RBE for alpha particles.

Roentgen Equivalent Man: rem = rad x RBE

1dose(rad) = 34.9 / ( ) 3490 /.01 /

radJ kg yr rad yearJ kg

⋅ =

dose = 3490 / (10) 34900 /rad yr rem year=

34900 / (1 / 365 )rem year year days=

95.6 /dose rem day=

dose = 34.9 /J kg yr⋅

Sample Problem

Immediate Health Effects? Long Term Effects?

Possible latent effects (cancer)

95.6 /dose rem day=

Immediate Health Effects? Long Term Effects?

IT DEPENDS ON WHO! 95.6 /dose rem day=

Long Term Uranium Health Risk The alpha radiation of the uranium isotopes U-238, U-235, and U-234 presents a radiation hazard on ingestion or inhalation of natural uranium. The beta radiation of Th-234 and Pa-234m,

together with the weak gamma radiation emitted by all nuclides, presents an external radiation hazard.

How do we know about the Health Effects

of Nuclear

Radiation?

Hiroshima Nagasaki 70,000 60,000

John Smitherman US Navy

"We watched the Baker shot from a ship about 19 miles away from the explosion, and mist from the mushroom fell on the deck of our ship and sand fell on our deck, little pieces of metal and rocks. We tried to wash off as much of it as we could. The mushroom cloud stayed in the air for almost two days- we could see that." Smitherman later developed lymphedema, a blockage of the lymph system that causes legs and arms to swell; he had to have both legs amputated. On September 11, 1983, he died of cancer of the colon, liver, stomach, lung and spleen. He had claimed compensation for radiation damages. The Veterans Administration turned his claim down seven times. It is still pending

Uranium Miner "I used to go in and haul the rocks out, and I guess that's where I got hurt, because there was a lot of dust after they did the blasting and we went in right away." - Bernard Benally Red Rock Navajo Reservation, Arizona

Animal Testing

The black star in the middle of the picture shows the tracks made by alpha rays emitted from a particle of pllutonium-239 in the lung tissue of an ape. The alpha rays do not travel very far, but once inside the body, they can penetrate more than 10,000 cells within their range. This set of alpha tracks (magnified 500 times) occurred over a 48-hour period.

Nuclear Processing Plant Accident 1999, Tokai, Japan: Uranium Processing Plant converts enriched uranium hexafluoride (UF6) to uranium dioxide (UO2) (MOX).

A Criticality accident involved a self-sustaining chain reaction caused from handling of too large amounts of enriched uranium. The chain reaction continued for around 20 hours, before it could be stopped, releasing large amounts of gamma and neutron radiation. 1 worker died.

Chernobyl Nuclear Power Plant Disaster, April 26th, 1986

Chernobyl reactor number 4 in Ukraine was ripped apart by an explosion on 26 April 1986, and burned for 10 days. It released a massive amount of radioactivity (1018 becquerels) over Europe and the rest of the world.

Human Radiation Experiments Hundreds of Secret Experiments of

Radioactive Material on Humans by the DOE 1944-1960

Obtained by Citizens by the Freedom of Information Act

Dr. Karl Z. Morgan, the Father of Health Physics @ Oak Ridge

National Lab

“There is no safe level of radiation exposure.”

Nuclear Power

Mass per Nucleon The smaller the mass per nucleon, the greater the binding energy. Elements fission down or fuse up to Iron, the most stable element,

releasing energy by E = ∆mc2.

Fission

Fusion

Binding Energy per Nucleon The most stable atoms have the most Binding Energy per nucleon.

Radioactive Atoms mutate by fission or fusion until they have maximum Binding Energy per nucleon which occurs at Iron.

In either FISSION or FUSION, less stable atoms mutate to more stable atoms, releasing energy in the process by E = mc2.

Fission & Fusion

Compare Reactions

n + U-235 -> Ba-143 + Kr-91 + 2 n

C + O2 -> CO2

H-2 + H-3 -> He-4 + n

Chemical @ 700K

Fission @ 1000K

Fusion @ 108K

Energy Released per kg of Fuel (J/kg)

3.3 x 107

2.1 x 1012

3.4 x 1014

Light elements FUSE into larger elements, releasing energy in the process by E = mc2.

Fusion

Proton-Proton Cycle

• The proton-proton cycle is a series of three nuclear reactions believed to operate in the Sun

• Energy liberated is primarily in the form of gamma rays, positrons and neutrinos

HHHeHeHeor

eHeHeHThen

HeHHeHHH

11

11

42

32

32

42

32

11

32

21

11

21

11

11

++→+

ν++→+

γ+→+

ν++→+

+

+

Fusion Fusion requires high temperature plasmas confined long enough to

release appreciable fusion energy

Confinement Method Heating Method

Gravity

•Compression (gravity) •Fusion Reactions (such as the p-p chain)

Stars

Fusion Fusion requires high temperature plasmas confined long enough to

release appreciable fusion energy

Confinement Method Heating Method

Inertial

•Compression (implosion driven by laser or ion beams, or by X-rays from laser or ion beams) •Fusion Reactions (primarily D+T)

Laser Beam Driven Fusioin

Fusion Fusion requires high temperature plasmas confined long enough to

release appreciable fusion energy

Confinement Method Heating Method

Magnetic

Tokamak

•Electromagnetic Waves •Ohmic Heating (by electric currents) •Neutral Particle Beams (atomic hydrogen) •Compression (by magnetic fields) •Fusion Reactions (primarily D+T)

Magnetic Bottles: Tokamaks Fusion requires high temperature plasmas confined long enough to release appreciable fusion energy

Currently the largest fusion reactor is the 16 MW Joint European Torus (JET) which can sustain plasmas of a few megawatts for a few seconds. The new ITER (International Thermonuclear Experimental Reactor) fusion reactor is planned to be built in France at a cost of $16 Billion. ITER is a tokamak design. It will take 8 years to build and will run experiments for 20 years.

Problems with Fusion?

Breeding it:

Breathing it:

Cost: ~ $200 million/kg Need ~ 56kg/year for the ITER

Tritium is RARE!

Tritium is RARE!

Dangerous Neutrons

DT fusion releases "fast neutrons." Fast neutrons turn everything they touch radioactive or busted. - Warren Smith

Cost of Fusion?

Budget: Fusion Energy Science: $428 Million

Average US Budget for Fusion Energy per year over past 50 years:

$250 Million x 50 years ~ $13 Billion so far

The great complexity and expense of fusion energy means that only wealthy countries

could afford it. Each machine would create a highly centralized source of enormous power (electrical and political), controlled by a few people.Unlike photovoltaic electricity and wind power that are inherently small-scale

and difficult to bring under centralized control, nuclear fusion lends itself to tight

control by powerful elites, both corporate and governmental.

- Fusion Illusions, Dr. Dittmar

The Power Source of the Future…and it always will be!

The Sun radiates 4 x 1023 kilowatts of Energy Solar Constant: 1.4kW/m2 at top of Earth’s Atmosphere US Average Power Received: 180W/m2

Heavy elements FISSION into lighter elements, releasing energy in the process by E = ∆mc2, where ∆m is the difference in mass

between the parent and products. About 250 MeV is released in this reaction in the form of kinetic energy of the products.

Nuclear Fission

Fission Described by the Liquid-Drop Model – Diagram

• (a) Approach (b) Absorption • (c) Oscillation (d) Fission

neutronsYX*UUn 23692

23592

10 ++→→+

Short History of Fission

• First observed in 1938 by Otto Hahn and Fritz Strassman following basic studies by Fermi – Bombarding uranium with neutrons produced

barium and lanthanum • Lise Meitner and Otto Frisch soon

explained what had happened – After absorbing a neutron, the uranium nucleus

had split into two nearly equal fragments – About 200 MeV of energy was released

“The Italian navigator has landed in the New World and found the natives very friendly.”

1st Nuclear Reactor 1938

Critical Mass – Chain Reaction Critical Mass: the minimum amount of fissionable material to produce self-sustained chain reaction, a condition called criticality. In a nuclear power plant, the critical chain reaction must control the neutron flux to avoid an exponential increase in fissions, going supercritical. In a nuclear bomb, you want a supercritical chain reaction.

( )1 235 141 92 10 92 56 36 03n U Ba Kr n+ → + +

Chain Reaction – Diagram

443 plants world wide (16% energy), 103 in the US (20% energy)

World Nuclear Power

Pressurized Water Reactor (PWR)

U-235 absorbs slow neutrons – they are slowed down by water – the neutrons become ‘thermalized’. Control rods absorb neutrons and moderate the chain reaction. A meltdown can happen if they fail.

The "outer building" surrounding Unit 3 of Fukushima I explodes due to the ignition of built up hydrogen gas, on March 13, 2011. This is the reactor which has the extremely dangerous plutonium-laced MOX fuel.

Basic Design of a Reactor Core

• Fuel elements consist of enriched uranium

• The moderator material helps to slow down the neutrons

• The control rods absorb neutrons

• All of these are surrounded by a radiation shield

K Values

• When K = 1, the reactor is said to be critical – The chain reaction is self-sustaining

• When K < 1, the reactor is said to be subcritical – The reaction dies out

• When K > 1, the reactor is said to be supercritical – A run-away chain reaction occurs

The reproduction constant K is defined as the average number of neutrons from each fission event that will cause

another fission event

Fissile Material of Choice U-235 & P-239

Odd number of nucleons is easier to fission U-235: 0.231 MeV more energy than U-238

Uranium: 238U is >99% in nature 235U is ~0.7% in nature. Fuels are generally enriched to at least a few percent 235U

Plutonium: 239Pu is not found in nature, it is reprocessed from nuclear power plant waste or “bred” from uranium in breeder reactors

Cooling Towers

Reactor

No green house gases are directly released in the nuclear fission reaction.

It is True...

But what about during the ENTIRE fuel cycle?

Uranium Mining

Uranium is mined as ore from open pits or deep shaft mines. High grade ores yield 10 kg uranium per tonne rock. World Nuclear Power Plants need 67,000 tonnes of natural

uranium per year – 67,000,000 tons of rock!

Uranium Miner "I used to go in and haul the rocks out, and I guess that's where I got hurt, because there was a lot of dust after they did the blasting and we went in right away." - Bernard Benally Red Rock Navajo Reservation, Arizona

Through a series of chemical leaching processes, crushed ore is transformed into a powdered concentrate called yellowcake. Most of the ore that goes into the mill exists as waste, which contains 85% of the ore's original radioactivity.

Uranium Mill Tailings The rock containing Uranium is crushed into a fine sand. After the uranium is chemically removed, the sand is stored in huge reservoirs. These left-over piles of radioactive sand are called "uranium tailings".

Uranium Mill Tailings

By 1989, some 140 million tons of mill tailings have accumulated in the United States alone, with 10 to 15 million tons added each year. Although their radiation is generally less concentrated than other types of waste, some of the isotopes in these tailings are long-lived and can be hazardous for many thousands of years.

Atlas Mines Tailing Pile

10.5 million tons of uranium mill wastes including 426 million gallons of highly-contaminated liquid. An Oak Ridge National Laboratory study shows that the steady rate of uranium tailing contaminant leakage into the Colorado River is estimated at 9,648 gallons per day.

Uranium Tailings at Elliot Lake Ontario

130 million tons radioactive for hundreds of thousands of years

Uranium Mill Sites

In-Situ Leach Mining

At an ISL site, a series of wells are drilled into the orebody. Millions of litres of strong acid or alkaline solution are then injected directly into the groundwater, stripping the uranium from the host rock and mixing it into the water. In the center of a circle of injection wells, a production well sucks most of the uranium bearing water up to the surface and pipes it into a processing plant where the uranium is recovered and the wastes are dealt with by either moving them elsewhere or pumping them back into the ground and thereby polluting the groundwater.

Nuclear Energy Institute Educational Website for Kids

In-Situ Leach Mining

Purified Yellow Cake in Aqueous Solution

converted into Uranium Hexafluoride gas UF6

Uranium Refiner, Blind River, Ontario, Canada.

Storing hexafloride (UF6) waste in cylinders requires constant monitoring because the estimated lifetime of cylinders is measured in decades, whereas the half-life of U-238 is 4.5 billion years, and UF6 is highly unstable.

Enriching Uranium Uranium: 238U is >99% in nature 235U is ~0.7% in

nature • Naturally occurring Uranium must be enriched to

~5% 235U for nuclear power plants • Enrichment methods

– Gas centrifuge (Now in Iran and formerly found in Iraq)

– Gaseous diffusion (used in USA) – Electromagnetic isotope separation – uses

strong magnetic field to deflect ions of lighter isotope farther than heavier isotope

Gaseous diffusion • Thousands of diffusion filters needed

Filter U-235 from U-238 through miles of filters

Portsmouth, Ohio, Gaseous Diffusion Plant operating around the clock, consuming in 1 day as much electricity as a city of the size of

Sacramento or Memphis, Tennessee.

CFC is a GHG The enrichment of uranium fuel for nuclear power uses 93 percent of the refrigerant chlorofluorocarbon (CFC) gas made annually in the United States. CFC compounds are also potent global warming agents 10,000 to 20,000 times more efficient heat trappers than carbon dioxide, which itself is responsible for 50 percent of the global warming phenomenon.

U-235: Converting the Gas into a Green salt and then into Metal

Uranium is shipped to Fernald from the Portsmouth plant as a gel. It is heated into gas in these three autoclave vaporizers. The gas is converted into green salt and then into metal for fuel fabrication.

Feed Materials Production Center, Fernald, Ohio.

These pellets of enriched uranium will be sealed inside 12-14 ft metal fuel rods to generate electricity in a nuclear reactor.

Nuclear Fuel Rods A typical 100 MW reactor contains 50,000 fuel rods containing more than 100 tons of uranium.

Cooling Towers

Reactor

Nuclear Power Plants Need Water – LOTS of Water.

100,000 gallons per minute are pumped to one or more Cooling Towers, consuming 28-30 million gallons of water per day. An equally huge volume of wastewater is discharged at temperatures up to 25 F hotter than the water into which it flows. Indigenous marine life suited to colder temperatures is eliminated or forced to move, disrupting delicately balanced ecosystems. Nuclear power plants discharge a significant amount of tritium as part of their routine operations; sometimes more is discharged as a result of mishaps and incidents. There have been 10 reported tritium leaks at US nuclear power plants in the last decade.

Nuclear Power Plants Need COOOOL Water!

SAN ONOFRE NUCLEAR GENERATING STATION Seawater for cooling: up to 2.4 billion gallons daily

“Once-through cooling is contributing to declining fisheries and the degradation of estuaries, bay and coastal waters. These (power) plants indiscriminately 'fish' the water in these habitats by killing the eggs, larvae and adults when water drawn from the natural environment flows through the plant.” -2005 analysis completed for the CA Energy Commission

Water Vapor is a GHG!

“The most powerful greenhouse gas in the atmosphere is water vapour... Just a rise of 1% of water vapour could raise the global average temperature of Earth's surface more then 4 degrees Celsius.” -Andrew E. Dessler, Texas A & M University -Vladimir Shaidurov, Russian Academy of Sciences The Science and Politics of Global Climate Change

After three or four years in a reactor, the pellets will become inefficient for producing electricity and the fuel rods will be removed from the reactor. After removal, the fuel rods (now called spent nuclear fuel) will be highly radioactive, requiring safe long-term disposal.

Present nuclear power plants utilise only 0.7 per cent of uranium and the remaining 99.3 per cent is the spent fuel Plutonium, which remains highly radioactive for over 10,000 years in the storage.

Nuclear Waste 250,000 tons of Spent Fuel Rods

10,000 tons made per year in US

The radioactive reactor building must also be decommissioned after 40-50 years of operation,

taken apart by remote control and similarly transported long distances and stored. GHG will be produced in the process. (The cost is paid by US taxpayers!)

Nuclear Waste Disposal Yucca Mountain, Nevada

77,000 Tons of High Level Waste

Yucca Mountain

Reprocessing the Hot Rods

THE RODS ARE FULL OF PLUTONIUM!

Plutonium:Nuclear Power By-Product •Each 1000 megawatt nuclear power plant produces 500 lbs of Pu per year. •Global production due to nuclear power plants: ~1,200 tons •Global production due to nuclear weapons: 250 tons. •5 kg in an atomic bomb!

The PROBLEM Iran, North Korea, India:

Every Nuclear Power Plant is a source for atomic weapons.

There is no “civilian” nuclear power. Nuclear Power must have military

protection because of the plutonium.

Reprocessing Plutonium • 239Pu is a waste product in nuclear power

reactors, that is intermixed with other spent reactor fuels.

• In order to become weapons grade, it must be separated out (“reprocessed”)

Reprocessing Plutonium • Spent reactor fuel is chopped up, by remote

control, behind heavy lead shielding. • Chopped-up pieces are then dissolved in boiling

nitric acid, releasing radioactive gases in the process.

• Pu is chemically separated from the acid solution, leaving large quantities of high-level radioactive liquid waste and sludge behind.

• After it has cooled down for several years, the liquid waste is solidified for ultimate disposal, while the separated Pu is fabricated into nuclear fuel or nuclear weapons.

Toxic Cities

Nuclear Processing Plant Accident 1999, Tokai, Japan: Uranium Processing Plant converts enriched uranium hexafluoride (UF6) to uranium dioxide (UO2) (MOX).

A Criticality accident involved a self-sustaining chain reaction caused from handling of too large amounts of enriched uranium. The chain reaction continued for around 20 hours, before it could be stopped, releasing large amounts of gamma and neutron radiation. 1 worker died.

1st Plutonium Factory Hanford, Washington

SuperFund Site: 35 Million Gallons of High Level Waste

A complete life-cycle analysis shows that generating electricity from nuclear power emits 20-40% of the carbon dioxide of a gas-fired system when the whole system is taken into account. Nuclear Power: The Energy Balance by Jan-Willem Storm van Leeuwen and Philip Smith, Center for Energy Conservation, Netherlands

In sum….Is nuclear power green?

High Grade Ore is a Limited Resource

Known uranium reserves will last for about fifty years at the current consumption rate. If the nuclear share is increased to 10% of the current world energy supply by construction of 1000 new nuclear power plants (more than four times the current world nuclear capacity), the reserves will last for about fourteen years. If low grade ores of less than 0.1% are used (1 kg of U per ton of rock) the energy consumed to extract the one kg of uranium will surpass the amount of energy which can be generated from that kilogram in the nuclear system.

“The main reason that no U.S. energy company has constructed one since 1973 is not public opposition, licensing, uncertainties, lack of licensed geological repository for spent fuel disposal, or proliferation risks, but rather that new commercial nuclear power plants are uneconomical because of their higher construction costs.”

Natural Resources Defense Council Issue Paper on Commercial Nuclear Power

The Energy Policy Act of 2005

•$14 billion in tax dollars, taxpayer-backed loans, and tax credits to build 6 new nuclear reactors. •$2 billion line item to compensate nuclear corporations for any delay •Price Anderson Act caps the industry’s liability at $15 billion

Three Mile Island: April 1979 Nuclear Power became unpopular after Three Mile Island when an accident caused the fuel rods to partially melt.

Three Mile Island: April 1979 13–17 million curies of radioactive iodine excaped in air 2.4–13 million cures of Xenon and Krypton (gamma emitters)

Chernobyl Nuclear Power Plant Disaster, April 26th, 1986

Chernobyl reactor number 4 in Ukraine was ripped apart by an explosion on 26 April 1986, and burned for 10 days. It released a massive amount of radioactivity (1018 becquerels) over Europe and the rest of the world.

Chernobyl released 50-80 million curies of radioactivity into the atmosphere

Average Background Radiation in Europe: 0.3 kBq/m2

1 Curie = 10 Billion Bq

•Evacuation of more than a thousand square miles

•400 times more radiation released than Hiroshima Bomb

•350,000 people dislocated

•Exclusion Zone is a permanent Ghost Town.

Local Effects

Chernobyl Now

The New Shelter

•600,000 exposed to high levels of radiation •6 million people exposed to low levels •56 deaths to date •4,000 cases of thyroid cancer to date •2 million officially classified as victims •Increased rates of birth defects •Hundreds of Billions of dollars in costs to date •9,000-90,000 cancer induced deaths will occur (Depending on who you’re talking to….)

Chernobyl Consequences

Our scientific power has outrun our spiritual power. We have guided missiles and unguided men. -Martin Luther King, Jr.

Nuclear Weapons

Hiroshima Nagasaki 70,000 60,000

August 6 August 9

Warheads, Bombs Missiles

Who has nuclear weapons?

US (1800)

Russia (2700) UK (55.5)

France (91.5)

China(400)

Israel (?)

All numbers in Mtons India(?)

Pakistan(?)

Thermonuclear

Fission

12,000 (Russia) 9,400 (USA) 300 (France) 240 (China) 225 (UK) 90 (Pakistan) 80 (India) 80 (Israel) 10 (N. Korea)

1945-now:Total US Cost: 7.5 Trillion Current Wordwide Cost: 1 Trillion/decade Peak of Cold War: Over 65,000 weapons. Kill factor ~ 20

One megaton (MT) is the explosive power of a million tons of TNT.

1 MT = 1000 kT = 106 tons = 109 kg = 1012 g

= 1,000,000,000,000 g

1 MT = 1015 calories

Total yield of all explosive bombs used in all warfare in the history of the world = 10 MT!

World Arsenal Nuclear Weapons: ~ 5,000 MT!

2053 Nuclear Bomb Tests 1945-1998

About 200 different radioactive substances are formed from a nuclear bomb explosion. Millions of curies of radioactivity in the form of dust and debris get carried into the upper atmosphere by the mushroom cloud. Jet stream winds can carry fallout from bomb blasts around the world within a few months. Atomic Tests released approximately

9 million curies of Sr-90. 1 Ci ≡ 3.7 x 1010 decays/s (Bq)

Picture taken by the US Defense Nuclear Agency in 1980, shows a huge dome, over top of a crater left by one of the 43 nuclear blasts on the island, capping off radioactive debris from nuclear tests over Runit Island in Enewetak in the Marshall Islands. A US study has found that the number of cancers caused by hydrogen bomb testing in the Marshall Islands is set to double, more than half a century after the tests were conducted in the tiny Pacific nation.

http://www.ctbto.org/specials/1945-1998-by-isao-hashimoto/

Nuclear Holocaust

Cities burn Ground bursts

Massive amounts of smoke Massive amounts of dust

Sunlight absorbed Sunlight reflected

Very little sunlight reaches the ground

Rapid, large surface temperature drops

“Nuclear Winter”

Nuclear Weapons Holocaust

http://www.fas.org/main/content.jsp?formAction=297&contentId=367

Current nuclear "overkill" ratio is at least 20.

Bulletin of the Atomic Scientists

Slide 0

We scientists recognize our inescapable responsibility to carry to our fellow citizens an understanding of atomic energy and its implication for society. In this lies our only security and our only hope - we believe that an informed citizenry will act for life and not for death. - Albert Einstein, January 22, 1947

If Not US, Who?