National Academies Press: OpenBook

Medical Isotope Production Without Highly Enriched Uranium (2009)

Chapter: Appendix G: Glossary

« Previous: Appendix F: Present Value Calculation
Suggested Citation:"Appendix G: Glossary." National Research Council. 2009. Medical Isotope Production Without Highly Enriched Uranium. Washington, DC: The National Academies Press. doi: 10.17226/12569.
Page 196
Suggested Citation:"Appendix G: Glossary." National Research Council. 2009. Medical Isotope Production Without Highly Enriched Uranium. Washington, DC: The National Academies Press. doi: 10.17226/12569.
Page 197
Suggested Citation:"Appendix G: Glossary." National Research Council. 2009. Medical Isotope Production Without Highly Enriched Uranium. Washington, DC: The National Academies Press. doi: 10.17226/12569.
Page 198
Suggested Citation:"Appendix G: Glossary." National Research Council. 2009. Medical Isotope Production Without Highly Enriched Uranium. Washington, DC: The National Academies Press. doi: 10.17226/12569.
Page 199

Below is the uncorrected machine-read text of this chapter, intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text of each book. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

Appendix G Glossary 6-day curies: The number of curies present in a shipment of Mo-99 6 days after it leaves a producer’s facilities. 6-day curies per week: The number of 6-day curies supplied in a week. Barns: A unit of measure of the fission cross section; 1 barn = 1 × 10–24 cm2. Becquerel (Bq): The SI derived unit of radioactivity, one Becquerel is equal to one radioactive disintegration per second. Breakthrough: The contamination of Mo-99 in the Tc-99m eluted from the column of a technetium generator that occurs after prolonged use. Brownfield conversion: Conversion within an existing processing facility or an unused facility with hot cells. Calandria: A sealed drum-shaped vessel that contains the heavy-water moderator for the reactor. This vessel is penetrated by a series of horizontal fuel channels and vertical channels for control rods. Casting: The process of melting a metal and pouring into a mold. Cold rolling: Process in which metal sheets are rolled at room temperature to maintain the metal’s original crystalline structure. Cold testing: Testing conducted without the use of radioactive material. Curie (Ci): A unit of radioactivity, defined as 1 Ci = 3.7 × 1010 decays per second. 196

APPENDIX G 197 Direct-use material: Material that is directly usable in nuclear weapons. Such materials include highly enriched uranium (HEU) and separated plutonium. Dissolution: The process of putting a material into solution. Downblend: Dilution of HEU with depleted uranium or natural uranium to convert it into low enriched uranium (LEU). Drug master file (DMF): A document submitted to the Food and Drug Administration (FDA) by a Mo-99 producer describing the facility in which the Mo-99 is made; the production process itself, including any raw materials used in production; and product test methods, specifications, stability, and release criteria that may be used as a source of information when FDA approval is sought. Eluting: Recovering an isotope (Tc-99m) by passing a saline solution through the alumina column of the generator. Enriched uranium: Uranium with a higher concentration of the U-235 isotope than found naturally. Enrichment: Process used to increase the concentration of the uranium-235 (U-235) isotope in a material relative to U-238. Fission: Process whereby a large atomic nucleus (such as uranium) is split into two (and sometimes three) smaller nuclei. Fission cross-section: Probability that a nucleus will capture a neutron and fission, usually expressed in barns. Fission fragments: Smaller atomic fragments resulting from fission of a large nucleus. Formula quantities: Special nuclear material in strategic quantities. For HEU this quantity is greater than 5 kg. Greater-Than-Class-C waste: Radioactive waste that contains concentrations of certain radionuclides above the Class C limits in 10 CFR §61.55. Greenfield construction: Construction of new facilities for producing and/or processing Mo-99. Half-life: The time required for a quantity of radioactive material to decay to half of its initial value. High-level waste: Highly radioactive materials containing fission products and transuranic elements produced as a byproduct of the reactions that occur inside nuclear reactors. Highly enriched uranium: Uranium enriched to concentrations greater than or equal to 20 percent by weight of U-235. Hot cell: Shielded workspace for working with highly radioactive materials.

198 APPENDIX G Hot rolling: Heating metal above its recrystalization temperature before rolling it to form sheets. Isomeric transition: Radioactive decay process in which the nucleus of a metastable isotope has an elevated energy state and releases this energy by emitting a gamma ray. Large-scale producer: Producers of Mo-99 who supply more than 1000 6-day curies of Mo-99 per week to the market on a routine basis. Low enriched uranium: Uranium enriched to concentrations less than 20 percent by weight of U-235. Medical isotopes: Class of radioactive isotopes (radioisotopes) that have unstable nuclei and emit radiation. This radiation is used for medical imaging and treatment. Neutron capture: Process involving the capture of neutrons by an atomic nucleus to form a heavier nucleus. Neutron flux: Measure of the intensity of neutron radiation, defined as the number of neutrons crossing a unit area of a square centimeter in one second (neutrons/cm2-s). New drug application (NDA): A written application to the Food and Drug Administration seeking approval to sell a pharmaceutical in the United States. Perfusion: Delivery of arterial blood to biological tissue. Perfusion reserve: Capacity of flow through a blood vessel system in an organ under a stress or stimulus. Regional producers: Producers who supply Mo-99 for indigenous or regional use in less than large-scale quantities. Significant quantity: Approximate quantity of material from which the possibility of manufacturing a nuclear explosive device (i.e., a device that can achieve a prompt critical mass) cannot be excluded. Special nuclear materials: Fissile material or material that is capable of sustaining a chain reaction of nuclear fission. It includes plutonium and uranium enriched in the isotopes U-233 or U-235. Stenosis: Abnormal narrowing of a blood vessel. Supplemental new drug application (sNDA): Additional written documenta­ tion submitted for approval by the FDA when a producer makes major changes to the process or raw materials it uses to make a pharmaceutical.

APPENDIX G 199 Target: Material containing U-235 that is designed to be irradiated in a nuclear reactor. Target cladding: Target encapsulation of aluminum or stainless steel that serves to protect the chemically reactive uranium metal or alloy and to contain the fission products produced during irradiation. Target meat: Uranium-bearing material in the target. Tc-99m kits: Chemicals (e.g., pharmaceutical agent, chelating compound, and saline solution) used to formulate a radiopharmaceutical to which Tc-99m is added. Technetium generator: Device used to store Mo-99 and extract its decay product Tc-99m. Technetium generator curies: Calibrated quantity of Mo-99 based on the number of curies that are contained in the generator on the day of or day after its delivery to the radiopharmacy, hospital, or clinic. Thermal neutron: Low-energy neutron of about 0.025 electron volts at room temperature. Tracer testing: Evaluation of the separations methods and processing of targets using very small amounts of radioactive material.

Next: Appendix H: Acronyms »
Medical Isotope Production Without Highly Enriched Uranium Get This Book
 Medical Isotope Production Without Highly Enriched Uranium
Buy Paperback | $65.00 Buy Ebook | $54.99
MyNAP members save 10% online.
Login or Register to save!
Download Free PDF

This book is the product of a congressionally mandated study to examine the feasibility of eliminating the use of highly enriched uranium (HEU2) in reactor fuel, reactor targets, and medical isotope production facilities. The book focuses primarily on the use of HEU for the production of the medical isotope molybdenum-99 (Mo-99), whose decay product, technetium-99m3 (Tc-99m), is used in the majority of medical diagnostic imaging procedures in the United States, and secondarily on the use of HEU for research and test reactor fuel.

The supply of Mo-99 in the U.S. is likely to be unreliable until newer production sources come online. The reliability of the current supply system is an important medical isotope concern; this book concludes that achieving a cost difference of less than 10 percent in facilities that will need to convert from HEU- to LEU-based Mo-99 production is much less important than is reliability of supply.


  1. ×

    Welcome to OpenBook!

    You're looking at OpenBook,'s online reading room since 1999. Based on feedback from you, our users, we've made some improvements that make it easier than ever to read thousands of publications on our website.

    Do you want to take a quick tour of the OpenBook's features?

    No Thanks Take a Tour »
  2. ×

    Show this book's table of contents, where you can jump to any chapter by name.

    « Back Next »
  3. ×

    ...or use these buttons to go back to the previous chapter or skip to the next one.

    « Back Next »
  4. ×

    Jump up to the previous page or down to the next one. Also, you can type in a page number and press Enter to go directly to that page in the book.

    « Back Next »
  5. ×

    To search the entire text of this book, type in your search term here and press Enter.

    « Back Next »
  6. ×

    Share a link to this book page on your preferred social network or via email.

    « Back Next »
  7. ×

    View our suggested citation for this chapter.

    « Back Next »
  8. ×

    Ready to take your reading offline? Click here to buy this book in print or download it as a free PDF, if available.

    « Back Next »
Stay Connected!