Department of Energy (DOE) Isotope Facilities
DOE owns national laboratories that are operated by contractors. Facilities at four of the national laboratories are involved in the routine production, processing, and distribution of isotopes for Isotope Program.
Hot cells, high flux reactors, and proton accelerators are used to produce and process radioisotopes beneficial to many people, programs, and plans.
Radioisotopes are produced in several ways. Some are made in reactors in which a high flux of neutrons is used to irradiate specially made target materials that capture these neutrons and thereby make the isotopes of interest. Other radioisotopes require a source of protons to drive the nuclear reactions responsible for their production. These isotopes are produced in accelerators where the subatomic, positively charged protons are sped up (accelerated) and then used to bombard targets in order to produce the required isotopes. Whether in reactors or accelerators, a high flux of protons or neutrons is required to make the isotope of interest. Still other radioisotopes are byproducts. They are produced from the natural decay of other materials. As an example, the medically useful isotope actinium-225 results from the decay of uranium-233. In order to purify it, the actinium has to be chemically separated from the uranium.
Reactors
|
High Flux Isotope Reactor (HFIR) |
The High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory (ORNL) provides one of the world's highest steady-state neutron fluxes. This reactor is a water-cooled reactor that uses highly enriched uranium-235 as fuel. HFIR contains more than 40 target locations within the core and reflector, with fluxes ranging from 4 x 1014 to 3 x 1015 neutrons per second per square centimeter. One target position has a hydraulic tube for rapid insertion and removal of targets while the reactor is running. This minimizes downtime. Two more hydraulic tubes are planned.
The Advanced Test Reactor (ATR) at the Idaho National Laboratory (INL), regularly produces radioisotopes. The 250-megawatt ATR has 18 major locations for experimental or radiation work and is unique in being able to adjust the local power and flux at the 18 locations. This provides unusual flexibility in the production of isotopes.
Accelerators
 |
Cross sectional view of the Isotope Production Facility
at Los Alamos National Laboratory. Radioisotopes are
produced underground. From there, the isotopes are
transported vertically above ground to a hot cell
for further processing. |
Construction of the Isotope Production Facility (IPF) at LANL was completed in September 2003. This IPF consists of a beam line that directs a portion of the 100 MeV proton beam from the main accelerator at The Los Alamos Neutron Science Center (LANSCE) to the IPF target station. Irradiated targets are removed from the beam line and transported directly to a hot cell for chemical processing. Many of the isotopes scheduled for production at IPF will provide for the future advancement of nuclear medicine applications and the continuation of human clinical studies.
The Brookhaven Linac Isotope Producer (BLIP) at BNL utilizes the excess beam of a linear accelerator that injects protons into the Alternating Gradient Synchrotron. Protons with energies up to 200 MeV may be produced at this facility.
Hot Cell Facilities
 |
Hot Cell Used For
Radioisotope Production |
Isotope Program makes use of hot cell facilities a ORNL, INL, LANL, and BNL. A hot cell is a closed work area in which radioactive materials may be manipulated without exposing the operator to radiation. Some cells are dedicated to the production of a single radioisotope in order to minimize contamination. Other cells are used to process a wide range of isotopes while still others are used for storage and transfer functions. They are an integral part of radioactive isotope production and their care and maintenance are high priorities.
Stable Isotope Enrichment Unit
Experts on the separation of stable isotopes have stated that the only single technology now capable of providing the full spectrum of enriched stable isotopes is electromagnetic separation. Generally, enriched stable isotopes are used as targets for the production of radioisotopes, for example, thallium-201 for heart imaging. Also, many are used as biological tracers such as carbon-13 in breath tests for ulcers. A large inventory of research isotopes exists at ORNL sufficient to serve research demand for at least five years for most isotopes. A small modern electromagnetic separator, based on an existing design could be installed at ORNL. The new machine would produce stable isotopes that are not commercially available and whose production is deemed to be in the best interest of the Nation's researchers.
DOE plans to eliminate obsolete capability and replace it with more efficient production capability to better serve researchers and provide stable isotopes at affordable prices.
Materials and Chemical Laboratories
The Isotope Research Materials Laboratory at ORNL was established in the 1960's primarily to prepare accelerator targets from enriched stable isotopes. As customer needs and isotope applications grew and diversified, a comprehensive materials processing laboratory evolved. A wide variety of chemical, metallurgical, ceramic, and high-vacuum processing techniques are now available for stable isotopes. Furthermore, because isotope needs are very diverse, and whereas one customer might want an isotope in one form and another customer the same isotope in a different form, Isotope Program also maintains an Isotope Chemical Laboratory at Oak Ridge. There, chemical purifications and transformations are performed on stable or long-lived radioactive isotopes to meet customer needs.
Byproducts and Stockpiled Materials
The program also obtains isotopes from the processing of byproducts and stored nuclear materials from other DOE programs. In fiscal year 2005, we processed Lithium-6.
Other stockpiled materials that could be processed for sale include cesium-137, actinium-227, uranium-232, americium-241, americium-243, curium-244, and a small amount of radium-226.
Stable Isotopes in Inventory
A large inventory of research isotopes exists at ORNL sufficient to serve research demand for several years and in many cases much longer. The program is planning to purchase and install a small isotope separator that will more affordably provide stable isotopes for research. This stable isotope separator will be operated year round.
|
