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Bioremediation Current Status, Prospects and Challenges
Published in Amitava Rakshit, Manoj Parihar, Binoy Sarkar, Harikesh B. Singh, Leonardo Fernandes Fraceto, Bioremediation Science From Theory to Practice, 2021
Ruby Patel, Anandkumar Naorem, Kaushik Batabyal, Sidhu Murmu
Technetium-99 is a long-lived (half-life, 2.13 × 105 years), beta-emitting radionuclide and is an important component of radioactive wastes. Under oxic conditions, technetium is present as pertechnetate ion (Tc (VII); TcO4-), which is one of the most mobile radionuclide species and less sorbed (Bondietti and Francis 1979). Bioreduction, a novel phosphor imaging technique, was used to show a reduction of the radionuclide by Shewanella putrefaciens and Geobacter metallireducens, with similar activities of Rhodobacter sphaeroides, Paracoccus denitrificans, some Pseudomonas species (Lloyd and Renshaw 2005), Escherichia coli (Lloyd et al. 1997) and a range of sulfate-reducing bacteria (Thiobacillus sp.) (Dhami 1998).
Treatment of Off-Gases from Process Operations
Published in Thomas E. Carleson, Nathan A. Chipman, Chien M. Wai, Separation Techniques in Nuclear Waste Management, 2017
Jerry D. Christian, Thomas R. Thomas
Technetium-99, again formed in significant quantities during the fission process, is of particular concern because of its long half-life (2.13 × 105 years) and its relative mobility in the environment. As indicated in Table 1, for LWR HLLW, the NRC effluent concentration limits could be met with virtually complete release of technetium. Its behavior in the solidification process is of interest because of the as-low-as-reasonably achievable (ALARA) aspects and operational considerations, given the fairly large quantities that are processed with the HLLW and the ability of technetium to volatilize at high temperatures.
Nuclear Terrorism
Published in Robert A. Burke, Counter-Terrorism for Emergency Responders, 2017
Radioactive materials have been the backbone of almost all medical advances that have occurred in the past 50 years. Nuclear technology plays a key role and often saves lives in medical clinics, hospitals, operating rooms, and pharmaceutical development. In addition to using radiation to diagnose medical problems, it is also used as a treatment for many diseases. Almost half of all Americans diagnosed each year with cancer undergo radiation therapy. Every hospital in this country has some type of radiation unit. Radioisotopes are administered to humans during medical procedures to either aid in the diagnosis of a disease or provide a treatment for a disease. This process is referred to as nuclear medicine. As a rule, radioisotopes used in medicine have very short half-lives (most times in terms of hours). They do not emit either alpha or beta radiation because these particulate radioactive materials would be deposited in the tissue of the body and cause serious damage. These isotopes are gamma emitters, which allow the medical procedure to obtain the best results. Radioisotopes used in medical procedures are usually not toxic and do not cause any pharmacological response in the patient. On the other hand, radioactive materials used for therapeutic purposes do emit alpha and beta particles as well as gamma rays. Primarily, the radioisotope technetium-99 (99Tc) is used in almost 80% of all daily diagnostic studies worldwide. Other radioisotopes used include thallium-201 (201Tl), gallium-67 (67Ga), indium-111 (111In), and iodine-123 (123I). Therapeutic procedures involve the use of the radioisotopes iodine-131 (131I), phosphorus-32 (32P), and yttrium-90 (90Y). Controls on the use, storage, and disposal of medical radioactive materials are tight. Terrorists could attempt to steal these materials for use in a nuclear dispersion device.
PHWR Reactivity Device Incremental Macroscopic Cross Sections and Reactivities for a Molybdenum-Producing Bundle and a Standard Bundle
Published in Nuclear Technology, 2022
In diagnostic nuclear medicine, a radiopharmaceutical consisting of a radioactive atom bound to a substrate molecule is administered to a patient to obtain functional information about the patient’s organs and to diagnose various medical conditions. Technetium-99 m (99mTc) is the most commonly used radionuclide in diagnostic nuclear medicine, 99mTc is produced from the radioactive decay of its parent nuclide, molybdenum-99 (99Mo). 99mTc is used in approximately 30 million procedures per year, accounting for 80% of all nuclear medicine diagnostic procedures worldwide.1 Neither 99Mo nor its daughter product, 99mTc, exist naturally. The parent nuclide, 99Mo, is most commonly produced through the fission of uranium-235 (235U) in nuclear reactors with a fission yield of 6.1% (Ref. 2). 99Mo has a half-life of ~4 days, which means that it reaches saturation activity in ~20 days, after which it needs to be harvested.3