Objectives To introduce fusion and fission as sources of energy To learn about nuclear fission To understand how a nuclear reactor works To learn about nuclear fusion To understand nuclear weapons To see how radiation damages human tissue

Two types of nuclear processes can produce energy A. Nuclear Energy Two types of nuclear processes can produce energy Combining 2 light nuclei to form a heavier nucleus - fusion Splitting a heavy nucleus into 2 nuclei with smaller mass numbers - fission Energy produced by conversion of mass, E = mc2 Sun converts 4 million tonnes per second Fusion and Fission POGIL

B. Nuclear Fission Each atomic fission produces 3 neutrons Releases 2.1 1013 J/mol uranium-235 (Burning methane produces 8.90 x 105 J/mol)

B. Nuclear Fission Chain reaction – self sustaining fission process caused by the production of neutrons that proceed to split other nuclei Chain Reaction Alternative CR Critical mass – mass of fissionable material required to produce a chain reaction

C. Nuclear Reactors

C. Nuclear Reactors Reactor core Nuclear Power Plants

B. Nuclear Fission Chernobyl 1 Chernobyl 2 Chernobyl 3 Nuclear Energy in the US?

D. Nuclear Fusion Process of combining two light nuclei Produces more energy per mole than fusion Powers the stars and sun

D. Nuclear Fusion Atoms lighter than Fe. Deuterium used Requires extremely high temperatures ~ 1 billion K Currently not technically possible for use as a power source – issues with confinement Used as “Hydrogen bomb” Sun’s energy captured for our use

Nuclear Binding Energy

Nuclear Weapons Fission Weapons (“Atomic Bombs”) Enriched uranium or plutonium Supercritical mass produced in bomb Limited up to 500 kilotons of TNT Twice used in warfare (Hiroshima and Nagasaki)

Nuclear Weapons Fusion Weapons (“Thermonuclear / Hydrogen Bombs”) deuterium and tritium fission bomb compresses and heats hydrogen fuel further stages of fission reactions (depleted uranium) largest so far is 57 megatons (“Tsar Bomba” - USSR) Radioactive fallout can be regulated – salted, neutron bomb

Missiles (land or submarine launch) Nuclear Weapons Delivery Gravity bombs Missiles (land or submarine launch) Multiple Independent Re-entry Vehicles “Tactical” weapons: shells, torpedoes “Now I am become Death, the destroyer of worlds” Strategy “Cold War, Arms Race” “Mutually Assured Destruction” Missile Defense Terrorist Threat WWII 1 2 3 4

Regulation UN, International Atomic Energy Agency Test Ban and Nuclear Non-Proliferation Treaties SALT’s and START’s (limitation and reduction) Still enough to destroy most human life on Earth (23,000 bombs equivalent to 150,000 Hiroshima bombs) US, Russia, China, UK, France, India, Pakistan, North Korea, Israel (?), South Africa (X) Obama (“World without nuclear weapons”) Nuclear Weapons

Factors Determining Biological Effects of Radiation E. Effects of Radiation Factors Determining Biological Effects of Radiation Energy of the radiation Penetrating ability of the radiation Ionizing ability of the radiation Cell repair, death (high dose / acute damage), incorrect repair (low dose / cancer) Chemical properties of the radiation source Strontium-90 and Radium-226 behave similarly to calcium so tend to accumulate in bones. Radioactive Iodine concentrates in the thyroid

Penetrating Ability of Radiation Alpha radiation consists of helium nuclei and is readily stopped by a sheet of paper. Beta radiation, consisting of electrons or positrons, is halted by an aluminum plate. Gamma radiation is dampened by lead

E. Effects of Radiation Rem: the quantity of ionizing radiation whose biological effect is equal to that produced by one roentgen of x-rays. Roentgen is a defined amount of ionization of dry air

U.S.Nuclear Regulatory Commission limit of 5,000 mrem/year above background for nuclear industry workers