Nuclear Reactors

What is fission again? Nuclear reactors take advantage of the process of nuclear fission which splits an atom and releases a great deal of energy FP = Fission Product

Quick Review of Nuclear Plants Nuclear Fission Generates Heat Water into Steam Drives Turbine Generates Electricity

Different Types of Power Plants In the US: – Pressurized Water Reactor – Boiling Water Reactor In general, most reactors are “Generation II,” such as the Fukushima Dai-ichi reactors Modern reactors are “Generation III” which are dramatically improved and more efficient – So-called “passive” safety measures which rely solely on natural laws such as gravity

Cut-Away of “Peach Bottom”

How is Radiation Contained? The nuclear core is contained within a “3.9 to 7.9 ft thick pre-stressed, steel-reinforced, air-tight concrete dome” to prevent escape

How is Waste Material Secured? Fuel can be replaced every months Two types of waste: – Low-Grade: Refers to materials in contact with the fuel rods, directly or indirectly – High-Grade: Refers to the spent nuclear material and byproduct Secured in underground pools and depots for several years in the plants or nearby Geologists study naturally occurring fission processes to better understand how to dispose of waste material

What could go wrong? Damage to the core due to loss of cooling – Due to loss of pressure – Due to loss of coolant – Due to uncontrolled power excursion Nuclear Meltdown – Not a technical term, but refers to the melting of nuclear material and a breach in the containment vessel

Worst-case When: – “A limiting fault … that leads to the failure of heat removal within the core ” – The Emergency Core Cooling System (ECCS) fails Then the core would heat beyond it’s melting point and turn into corium causing a containment breach

Radiation in the Environment Iodine 129 and 131 are radioactive and can be absorbed by the body causing thyroid cancer Acute radiation syndrome Stunted growth and death in local wildlife Increase in mutations in humans and other animals Groundwater absorbs radionuclides

Naturally Occurring Fission First found in Oklo in Gabon, Africa by physicist Francis Perrin These reactions occurred about 2 billion years ago, and were self-sustained for some hundred thousand years Scientists are studying this process to better learn how radioactive material travels through the Earth’s crust and how to contain radioactive inert gases release 1. Nuclear reactor zones 2. Sandstone 3. Uranium ore layer 4. Granite