Beta particle. 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. Beta particles are high-energy, high-speed electrons or positrons emitted by certain types of radioactive nuclei such as potassium-40. The beta particles emitted are a form of ionizing radiation also known as beta rays. The production of beta particles is termed beta decay. Β− decay (electron emission)[edit] Beta decay. An unstable atomic nucleus with an excess of neutrons may undergo β− decay, where a neutron is converted into a proton, an electron and an electron-type antineutrino (the antiparticle of the neutrino): n → p + e− + ν e This process is mediated by the weak interaction. Beta decay commonly occurs among the neutron-rich fission byproducts produced in nuclear reactors.
Β+ decay (positron emission)[edit] p → n + e+ + ν e Interaction with other matter[edit] Uses[edit] Alpha particle. Alpha particles consist of two protons and two neutrons bound together into a particle identical to a helium nucleus. They are generally produced in the process of alpha decay, but may also be produced in other ways. Alpha particles are named after the first letter in the Greek alphabet, α.
The symbol for the alpha particle is α or α2+. Because they are identical to helium nuclei, they are also sometimes written as He2+ or 4 2He2+ indicating a Helium ion with a +2 charge (missing its two electrons). If the ion gains electrons from its environment, the alpha particle can be written as a normal (electrically neutral) Helium atom 4 2He. The nomenclature is not well defined, and thus not all high-velocity helium nuclei are considered by all authors as alpha particles.
Alpha particles, like helium nuclei, have a net spin of zero. Sources of alpha particles[edit] Alpha decay[edit] The most well-known source of alpha particles is alpha decay of heavier (> 106 u atomic weight) atoms. [edit] Plutonium. Plutonium is the heaviest primordial element by virtue of its most stable isotope, plutonium-244, whose half-life of about 80 million years is just long enough for the element to be found in trace quantities in nature.[3] Plutonium is mostly a byproduct of nuclear reactions in reactors where some of the neutrons released by the fission process convert uranium-238 nuclei into plutonium.[4] Both plutonium-239 and plutonium-241 are fissile, meaning that they can sustain a nuclear chain reaction, leading to applications in nuclear weapons and nuclear reactors.
Plutonium-240 exhibits a high rate of spontaneous fission, raising the neutron flux of any sample containing it. The presence of plutonium-240 limits a plutonium sample's usability for weapons or its quality as reactor fuel, and the percentage of plutonium-240 determines its grade (weapons grade, fuel grade, or reactor grade). Plutonium-238 has a half-life of 88 years and emits alpha particles. Characteristics Physical properties. Atomic Insights Blog. Very high temperature reactor.
Very-high-temperature reactor scheme. The very-high-temperature reactor (VHTR), or high-temperature gas-cooled reactor (HTGR), is a Generation IV reactor concept that uses a graphite-moderated nuclear reactor with a once-through uranium fuel cycle. The VHTR is a type of high-temperature reactor (HTR) that can conceptually have an outlet temperature of 1000 °C. The reactor core can be either a "prismatic block" or a "pebble-bed" core. The high temperatures enable applications such as process heat or hydrogen production via the thermochemical sulfur–iodine cycle.
Overview[edit] AVR in Germany. The VHTR is a type of high-temperature reactor that conceptually can reach higher outlet temperatures (up to 1000 °C); however, in practice the term "VHTR" is usually thought of as a gas-cooled reactor, and commonly used interchangeably with "HTGR" (high-temperature gas-cooled reactor). The Russian VHTR is also a HTGR. History[edit] Nuclear reactor design[edit] Neutron moderator[edit] Nuclear fuel[edit] Accelerating Future » A Nuclear Reactor in Every Home.
Sometime between 2020 and 2040, we will invent a practically unlimited energy source that will solve the global energy crisis. This unlimited source of energy will come from thorium . A summary of the benefits, from a recent announcement of the start of construction for a new prototype reactor: There is no danger of a melt-down like the Chernobyl reactor. It produces minimal radioactive waste. It can burn plutonium waste from traditional nuclear reactors. If nuclear reactors can be made safe and relatively cheap, how popular could they get? It depends on how cheap we’re talking about. State-of-the-art nuclear reactors, such as Westinghouse’s AP1000 , cost $1.5 billion to build and produce 1.1 gigawatts of electricity.
The AP1000 is a Generation III reactor, a new class of reactor that started coming online in 1996. That something is huge safety restrictions. The world-changing thorium reactor I am envisioning qualifies as a Generation IV reactor. Thorium reactors will be cheap. Uranium Is So Last Century — Enter Thorium, the New Green Nuke | Magazine. Photo: Thomas Hannich The thick hardbound volume was sitting on a shelf in a colleague’s office when Kirk Sorensen spotted it. A rookie NASA engineer at the Marshall Space Flight Center, Sorensen was researching nuclear-powered propulsion, and the book’s title — Fluid Fuel Reactors — jumped out at him. He picked it up and thumbed through it. Hours later, he was still reading, enchanted by the ideas but struggling with the arcane writing. “I took it home that night, but I didn’t understand all the nuclear terminology,” Sorensen says. Published in 1958 under the auspices of the Atomic Energy Commission as part of its Atoms for Peace program, Fluid Fuel Reactors is a book only an engineer could love: a dense, 978-page account of research conducted at Oak Ridge National Lab, most of it under former director Alvin Weinberg.
At the time, in 2000, Sorensen was just 25, engaged to be married and thrilled to be employed at his first serious job as a real aerospace engineer. Thorium fuel cycle. The thorium fuel cycle is a nuclear fuel cycle that uses the naturally abundant isotope of thorium, 232Th, as the fertile material. In the reactor, 232Th is transmuted into the fissile artificial uranium isotope 233U which is the nuclear fuel. Unlike natural uranium, natural thorium contains only trace amounts of fissile material (such as 231Th), which are insufficient to initiate a nuclear chain reaction. Additional fissile material or another neutron source are necessary to initiate the fuel cycle. In a thorium-fueled reactor, 232Th absorbs neutrons eventually to produce 233U. The thorium fuel cycle claims several potential advantages over a uranium fuel cycle, including thorium's greater abundance, superior physical and nuclear properties, better resistance to nuclear weapons proliferation[1][2][3] and reduced plutonium and actinide production.[3] History[edit] [edit] Fission product wastes[edit] Actinide wastes[edit] Uranium-232 contamination[edit] Advantages as a nuclear fuel[edit]
The Liquid Fluoride Thorium Reactor: What Fusion Wanted To Be. Reactor. Thorium reactors would be cheap. The primary cost in nuclear reactors traditionally is the huge safety requirements. Regarding meltdown in a thorium reactor, Rubbia writes, “Both the EA and MF can be effectively protected against military diversions and exhibit an extreme robustness against any conceivable accident, always with benign consequences. In particular the [beta]-decay heat is comparable in both cases and such that it can be passively dissipated in the environment, thus eliminating the risks of “melt-down”. Thorium reactors can breed uranium-233, which can theoretically be used for nuclear weapons.
However, denaturing thorium with its isotope, ionium, eliminates the proliferation threat. Like any nuclear reactor, thorium reactors will be hot and radioactive, necessitating shielding. Because thorium reactors will make nuclear reactors more decentralized. Even smaller reactors might be built. The primary limitation with nuclear reactors, as always, is containment of radiation. Energy from Thorium. New age nuclear. Credit: Justin Randall What if we could build a nuclear reactor that offered no possibility of a meltdown, generated its power inexpensively, created no weapons-grade by-products, and burnt up existing high-level waste as well as old nuclear weapon stockpiles?
And what if the waste produced by such a reactor was radioactive for a mere few hundred years rather than tens of thousands? It may sound too good to be true, but such a reactor is indeed possible, and a number of teams around the world are now working to make it a reality. What makes this incredible reactor so different is its fuel source: thorium. Named after Thor, the warlike Norse god of thunder, thorium could ironically prove a potent instrument of peace as well as a tool to soothe the world’s changing climate. But nuclear power comes with its own challenges. A thorium reactor is different. That may not sound like much, but small changes in the global average can mask more dramatic localised disruptions in climate. Thorium. (Updated March 2014) Thorium is more abundant in nature than uranium.It is fertile rather than fissile, and can only be used as a fuel in conjunction with a fissile material such as recycled plutonium.Thorium fuels can breed fissile uranium-233 to be used in various kinds of nuclear reactors.Molten salt reactors are well suited to thorium fuel, as normal fuel fabrication is avoided.
The use of thorium as a new primary energy source has been a tantalizing prospect for many years. Extracting its latent energy value in a cost-effective manner remains a challenge, and will require considerable R&D investment. This is occurring preeminently in China, with modest US support. Nature and sources of thorium Thorium is a naturally-occurring, slightly radioactive metal discovered in 1828 by the Swedish chemist Jons Jakob Berzelius, who named it after Thor, the Norse god of thunder. When pure, thorium is a silvery white metal that retains its lustre for several months.
Thorium as a nuclear fuel. Interactive: A Visual Guide Inside Japan's Reactors. A is for Atom (1952) - Educational Animated Film - Part 1/2. Our Friend the Atom 1 of 5 - The Fisherman and the Genie. Our Friend the Atom 5 of 5 - Harnessing the Atom. Our Friend the Atom 4 of 5 - Nuclear Reactions. Our Friend the Atom 2 of 5 - Atoms and Molecules. Our Friend the Atom 3 of 5 - What's in an Atom. Nuclear crisis: 'Chain reaction could restart' 1800 GMT, 18 March 2011 Zena Iovino, reporter Japan has raised the accident level at the Fukushima Daiichi nuclear power plant to 5 on an international scale of 7, according to the Kyodo news agency and NHK.
The partial meltdown at Three Mile Island in 1979 also ranked as a level 5. But there was some good news. The International Atomic Energy Agency (IAEA) said on Friday that the situation at reactors 1, 2 and 3 appears to remain fairly stable. The spent-fuel ponds at units 3 and 4, however, remain an important safety concern. Reliable, validated information is still lacking on water levels and temperatures at the spent fuel ponds, but the IAEA announced on Friday that prior to the earthquake, The entire fuel core of reactor unit 4 of the Fukushima Daiichi nuclear power plant had been unloaded from the reactor and placed in the spent fuel pond located in the reactor's building.
Meanwhile, the Tokyo Electric Power Company is continuing its attempts to restore electrical power to the plant. Japan's nuclear crisis: The story so far - environment - 15 March 2011. Read full article Continue reading page |1|2 With muddled media reports of the ongoing crisis, we spell out exactly what has happened up to 15 March, and what might happen next Which reactors have been hit hardest by the quake, and where are they?
Two major nuclear power plants are at the heart of the crisis, both of which were hit by the quake and the tsunami. They are on the coast halfway between Sendai, the city which bore the brunt of the tsunami, and Tokyo. The first, called Fukushima Daiichi – literally, Fukushima Number 1 – has six units, each housing its own nuclear reactor. Only the first three units were working when the quake struck. The second power plant involved, Fukushima Daini – Fukushima Number 2 – has four units, and all were working at the time of the quake. Did everything work as planned initially? As with all nuclear power stations in Japan, the reactors are fitted with quake sensors that shut them down automatically at the first sign of potentially hazardous tremors.
GCSE Bitesize: Nuclear fission. Learning Zone Class Clips - An introduction to nuclear fission - Science Video.