energy society - university of notre damensl/lectures/phys20051_2012/nuclear_energy... · 2012. 10....

Energy and

Society

Nuclear EnergyCan we reach for a sustainable and attainable energy Future?

Chapter 7 + handouts

Thursday September 27, 2012

The mission of the Organization for Economic Co-operation and Development (OECD) is to promote policies that will improve the economic and social well-being of people around the world.

OECD countries

Assignment for Tuesday Oct. 2, 2012

Worldwide Excitement about Nuclear Science

Nuclear Power or Nuclear Energy

“As a zero-carbon energy source, nuclear power must be part of our energy mix as we work toward energy independence and meeting the challenge of global warming.”

— Nobel physicist Steven Chu, U.S. Secretary of Energy - May 6, 2009

Complicated

Related to Nuclear Weapons…. Atoms for Peace program

Fear/Emotion

Lack of understanding/knowledge

Expensive

Radioactive Waste

http://www.maniacworld.com/Tsar-Nuclear-Explosion.html

http://www.maniacworld.com/Tsar-Nuclear-Explosion.html

"Atoms for Peace" was the title of a speech delivered by U.S. President Dwight D. Eisenhower to the UN General Assembly in

New York City on December 8, 1953.

• "It is with the book of history, and not with isolated pages, that the United States will ever wish to be identified. My country wants to be constructive, not destructive. It wants agreement, not wars, among nations. It wants itself to live in freedom, and in the confidence that the people of every other nation enjoy equally the right of choosing their own way of life."

• "To the making of these fateful decisions, the United States pledges before you--and therefore before the world--its determination to help solve the fearful atomic dilemma--to devote its entire heart and mind to find the way by which the miraculous inventiveness of man shall not be dedicated to his death, but consecrated to his life."

Isotopes for the Nation’s Future

Ani AprahamianUniversity of Notre Dame

Background

Isotopes are vital to the science and technology base of the US economy.

medicinebiologyphysicschemistryenvironmental sciencesmaterial studiesnew resource development – petrochemical, nuclear, bio-fuelshomeland security

Atoms for Peace program……1954

US Department of Energy …..Office of Nuclear Energy

Isotopes used as environmental tracers.

For example:• As-73 is needed to understand As contamination and transport.

• Na-22, Sr-87, and other solute reactive isotopes are needed to understand flowpaths for geochemical and hydrologic modeling.

• Al-26 is needed to understand the impacts of acid rain.

• Si-32 is needed for oceanographic tracing, which contributes to a better understanding of climate change and its effects.

Nuclear Physics Applications

EnergyADS systemsFusion confinementNuclear WasteNuclear Data

Life ScienceMedical DiagnosticsMedical TherapyRadiobiologyBiomedical tracers

Nuclear ForensicsHomeland SecurityRisk AssessmentsNuclear TraffickingProliferation

Material AnalysisIon Implantation Material StructureGeology & ClimateEnvironmentArt & Archaeology

Nuclear DefenseWeapon Analysis Functionality SimulationLong-Term Storage

Nuclear Imaging

Gamma CameraSPEC & PEP

Tumor mapping & visualization by radioactive isotope accumulation.

Blood flow with radiopharmaceuticals

Imaging system development

Imaging software and analysis

BrachytherapyGamma therapyNeutron therapyHeavy ion therapy

Radiation Treatment

Fission/Fusion Reactors for the Future

The Tokomak approach ITER The laser approach NIF

Magnet field confined plasma fusion Laser ignition fusion

Nuclear Energy Accelerator Driven Systems (ADS) for operating sub-critical reactors

ADS for nuclear waste management

From nuclear power plants

to nuclear pace makersBeam optics &

irradiation system development

Incineration strategies

1GeV accelerator development (~10 15 n/s)

Implantation and irradiationfrom silicon chips to solar sails

Dating real and false mummies

Material Treatment and Analysis of Artifacts

Nuclear Forensicshomeland security

Trafficking of nuclear materials & material loss assessments

Border control & radiation exposure (instrumentation)

Provenance of radioactive material by isotope composition or material structure analysis

Signature identification, Detector array developmentSensitivity analysis

Nuclear Energy Facts

Do not use Fossil Fuels

Energy from fission of Uranium

Or

New International program ITER in France….180 country international project!!

No carbon emissions to the atmosphere

CO2, SO2, CO (what renewables??)

20% of US energy needs met by nuclear power plants…most of them old!

None built over 30 yrs….

Location of Projected New Nuclear Power Reactorshttp://www.nrc.gov/reactors/new-reactors/col/new-reactor-map.html

There are currently 104 licensed to operate nuclear power plants in the United States (69 PWRs and 35 BWRs), which generate about 20% of our nation's electrical use.

Pressurized Water Reactors (PWRs)Boiling Water Reactors (BWRs)

.

E=mc2

Each fission releases more than 1 neutron

Uranium has two isotopes235 (0.7%) and 238 (99.3%)

The amount of free energy contained in nuclear fuel is millions of times the amount of free energy contained in a similar mass of chemical fuel such as gasoline, making nuclear fission a very tempting source of energy; however, the products of nuclear fission are radioactive and remain so for significant amounts of time, giving rise to a nuclear waste problem.

Concerns over nuclear waste accumulation and over the destructive potential of nuclear weapons may counterbalance the desirable qualities of fission as an energy source, and give rise to ongoing political debateover nuclear power.

History

Univ. of Chicago…Enrico FermiManhattan Project….Oppenheimer ledAtoms for Peace- 1953

President Eisenhower to United Nations1954 –Atomic Energy Act

Periodic Table of the Elements

The Nuclear ChartProton: 2 up, 1 down quark

Neutron: 2 down, one up quark

Gluons: quark antiquark

Chart of Nuclides

Atomic Number = number of protonsAtomic Mass = number of protons + number of neutronsWhat is Atomic Weight?

Where is the Energy coming from??????

Splitting the Uranium Atom: Uranium is the principle element used in nuclear reactors and in certain types of atomic bombs. The specific isotope used is 235U. When a stray neutron strikes a 235U nucleus,it is at first absorbed into it. This creates 236U. 236U is unstable and this causes the atom to fission.

•235U + 1 neutron 2 neutrons + 92Kr + 142Ba + ENERGY •235U + 1 neutron 2 neutrons + 92Sr + 140Xe + ENERGY

Radioactivity

Americium -241: Used in many smoke detectors for homes and business...Cadmium -109: Used to analyze metal alloys for checking stock, sorting scrap. Calcium - 47: Important aid to biomedical researchers studying the cell function and bone formation of mammals. Californium - 252: Used to inspect airline luggage for hidden explosives...to gauge the moisture content of soil in the road construction and building industries...and to measurethe moisture of materials stored in silos. Carbon - 14: Helps in research to ensure that potential new drugs are metabolized without forming harmful by-products. Cesium - 137: Used to treat cancers...Chromium - 51: Used in research in red blood cell survival studies. Cobalt - 57: Used in nuclear medicine to help physicians interpret diagnosis scans of patients' organs, and to diagnose pernicious anemia. Cobalt - 60 : Used to sterilize surgical instruments...spices/fruitsCopper - 67: cancer

Radioactivity

Alpha decayBeta decayElectron captureGamma Decay

Half-life

very shortvery long- longer than age of earth….billions of yrs14C 5730 yrs

Alpha Decay

Beta Decay

Gamma Decay

Number ofhalf-lives

elapsed

Fractionremaining

Percentageremaining

0 1/1 100

1 1/2 50

2 1/4 25

3 1/8 12 .5

4 1/16 6 .25

5 1/32 3 .125

6 1/64 1 .563

7 1/128 0 .781

... ... ...

n 1/2n 100(1/2n)

Half-lives are very often used to describe quantities undergoing exponential decay—for example radioactive decay—where the half-life is constant over the whole life of the decay.

A quantity is said to be subject to exponential decayif it decreases at a rate proportional to its value. Symbolically,

this can be expressed as the following differential equation, where N is the quantity and λ is a positive number called the decay constant.

The solution to this equation is:

Here N(t) is the quantity at time t, and N0 = N(0) is the initial quantity, i.e. the quantity at time t = 0.

Half-life:time required for the decaying quantity to fall to one half of its initial value

This time is called the half-life, and often denoted by the symbol t1 / 2. The half-life can be written in terms of the decay constant, or the mean lifetime, as:

Example: 14C…..0.693/5730 yrs =1.21 x10-4 /yr

Example: How old is an object whose 14C content is 10% of what it is in living organisms today?

.

or l=ln2/t 1/2

Environmental and safety aspects of nuclear energy

Not in My Back YuccaWhat are our alternatives for storing radioactive waste?By Brendan I. KoernerPosted Tuesday, April 15, 2008, at 8:11 AM ET

Environmental Statement on NuclearEnergy and Global WarmingJune 2005

Too expensive – power plants…Too dangerous- terrorist groupsToo polluting- radioactive waste

Thorium: Is It the Better Nuclear Fuel?

What is special about thorium?

(1) Weapons-grade fissionable material (uranium233) is harder to retrieve safely and clandestinely from the thorium reactor than plutonium is from the uranium breeder reactor.

(2) Thorium produces 10 to 10,000 times less long-lived radioactive waste than uranium or plutonium reactors.

(3) Thorium comes out of the ground as a 100% pure, usable isotope, which does not require enrichment, whereas natural uranium contains only 0.7% fissionable U235.

(4) Because thorium does not sustain chain reaction, fission stops by default if we stop priming it, and a runaway chain reaction accident is improbable.

Here is the thorium sequence in the Rubbia reactor: A neutron is captured by

90Th232, which makes it 90Th233.

90Th232 + 0n1 -> 90Th233 [1]

Thorium-233 spontaneously emits a beta particle (an electron from the nucleus, see p 173), leaving behind one additional proton, and one fewer neutron. ("...Nuclear Energy" p134) This is called "beta decay."

90Th233 -> 91Pa233 + ß [2]

The element with 91 protons is Protactinium (Pa). The isotope 91PA233 also undergoes beta decay,

91Pa233 -> 92U233 + ß [3]

The U233 isotope that is produced in step [3] is fissionable, but has fewer neutrons than its heavier cousin, Uranium-235, and its fission releases only 2 neutrons, not 3.

92U233 + 0n

1 -> fission fragments + 20n1 [4]

Fusion Energy (how the sun gets its energy)

In a fusion reaction, two light atomic nuclei fuse together to form heavier ones, as is shown in the figure. The fusion process releases a large amount of energy, which is the energy source of the sun and the stars.

Proton + neutron=deuterium

Proton + 2 neutrons=tritium

D+ T= 4He +n + 17.6 MeV2H+ 3H=4He

Fusion energy

Fusion Inside the Stars

• Fusion in the core of stars is reached when the density and temperature are high enough. There are different fusion cycles that occur in different phases of the life of a star. These different cycles make the different elements we know. The first fusion cycle is the fusion of hydrogen into Helium. This is the stage that our Sun is in.

The long-term objective of fusion research is to harness the nuclear energy provided by the fusion of light atoms to help meet mankind´s future energy needs.