Nuclear energy for the third millennium
The major energy sources of today are expected to last for only a small fraction of the millennium starting three years hence. In the plans of most people, nuclear energy has been ruled out for four separate reasons: 1. The danger of radioactivity from a reactor accident or from reactor products during a long period after reactor shutdown; 2. The proposed fuels, U-235 and also Pu-239, as obtained by presently available procedures will serve only for a limited duration; 3. Energy from nuclear reactors will be more expensive than costs of present alternatives; 4. The possibility of misusing the products for military purposes is an unacceptable danger. The development described below 1 attempts to meet all four objections. Specifically, we propose a structure as an example of future reactors that is deployed two hundred meters underground in loose and dry earth. The reactor is designed to function for thirty years, delivering electrical power on demand up to a level of thousand electrical megawatts. From the time that the reactor is started to the time of its shutdown thirty years later, the functioning is to be completely automatic. This is an obviously difficult condition to fulfill. The most important factor in making it possible is to design and operate the reactor without moving mechanical parts. At the start, the reactor functions on thermal neutrons within a structure containing uranium enriched in U-235 or having an addition of plutonium. That part of the reactor is to deliver energy for approximately one year after which a neighboring portion of the reactor containing thorium has been converted into Th-233 which rather rapidly decays into fissile U-233. This part of the assembly works on fission by fast neutrons. It will heat-up if insufficient thermal energy is withdrawn from the reactor`s core, under the negative feedback action of engineered-in thermostats. Indeed, these specifically designed thermostatic units absorb neutrons if excessive reactor core heating occurs in order to decrease heat generation and to act like automatic control rods. These units will be described below. After the thorium in a given volume of the reactor`s fuel charge is depleted, an adjacent thorium-containing portion of the fuel charge will have been converted bred into fissile material and is ready to continue the reaction. A schematic representation of this concept is shown in Figure 1. Actually, the thorium `reactors` in this Figure will be merged together into a single reactor system with the nuclear fuel-burning reactions propagating down to the ultimate `reactor` U. (In practice, we consider placing the fuel-igniting charge in the middle of the reactor system`s `fuel stick` and arrange breeding regions on both sides, shown in Figure 3.) After all the thorium in the reactor`s fuel charge has been used up, the reactor is shut down by the first positive action of the operators in thirty years. The residual radioactivity will be sealed within the reactor`s core and thereafter allowed to decay in place. The initially intense radioactivity will leave the reactor products inaccessible and unusable for military purposes except if complicated, expensive and easily observed large-scale operations are performed. Having thereby avoided transportation of fission products and reprocessing significantly reduces cost and hazards.
- Research Organization:
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- Sponsoring Organization:
- USDOE Assistant Secretary for Nuclear Energy, Washington, DC (United States)
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 325423
- Report Number(s):
- UCRL-JC-129547; CONF-9710142-; ON: DE98052187; BR: YN0100000; TRN: 99:003640
- Resource Relation:
- Conference: International conference on environment and nuclear energy, Washington, DC (United States), 27-29 Oct 1997; Other Information: PBD: 1 Oct 1997
- Country of Publication:
- United States
- Language:
- English
Similar Records
DAMAGE TO MITOCHONDRIAL ELECTRON TRANSPORT AND ENERGY COUPLING BY VISIBLE LIGHT
PEBBLE BED REACTOR PROGRAM. Progress Report for June 1, 1958-May 31, 1959