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The division's objectives are to promote the advancement of knowledge and understanding of the fundamental physical phenomena characterizing nuclear reactors and other nuclear systems. The division encourages research and disseminates information through meetings and publications. Areas of technical interest include nuclear data, particle interactions and transport, reactor and nuclear systems analysis, methods, design, validation and operating experience and standards. The Wigner Award heads the awards program.
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Norway’s Halden reactor takes first step toward decommissioning
The government of Norway has granted the transfer of the Halden research reactor from the Institute for Energy Technology (IFE) to the state agency Norwegian Nuclear Decommissioning (NND). The 25-MWt Halden boiling water reactor operated from 1958 to 2018 and was used in the research of nuclear fuel, reactor internals, plant procedures and monitoring, and human factors.
Katsuyoshi Tatenuma, Yukio Hishinuma, Satoshi Tomatsuri, Kousaburo Ohashi, Yoshiharu Usui
Nuclear Technology | Volume 124 | Number 2 | November 1998 | Pages 147-164
Technical Paper | Decontamination/Decommissioning | doi.org/10.13182/NT98-A2915
Articles are hosted by Taylor and Francis Online.
A new gas-phase decontamination technology is developed based on gaseous reactions utilizing the volatile properties of the carbonyl and fluoric compounds of radioactive transition elements and actinides (corrosion products, fission products, and transuranium) on a material's surface. The feasibility of this new technology is determined by removing nonradioactive (Co, Cr, Ni, Re, Mo, Mn, Ru, and Zn) and radioactive (60Co, 63Ni, and 103Ru) nuclide transition elements as gaseous forms under high CO pressure (50 to 200 atm) and high temperature (~350°C). Experiments involving U and using fluoric gases are also performed. For radioactive nuclides existing in an oxide layer of stainless steel, pretreatment with supercritical CO2 + I2 + H2O is used to remove the oxide layer completely, and by the subsequent gaseous reaction, 95 to 99% of 60Co is removed from the layer by CO gas treatment at a pressure of 200 atm. The plasma treatment using fluorine gas results in U being removed with high efficiency (~60%) after only 5 min, even at a reduced pressure of 1 Torr and at room temperature. When the carbonyl and fluoric species generated from a nontoxic gas mixture (1 Torr) of CF4 and O2 is used, U and 60Co are removed simultaneously with high removal efficiencies of 80 and 100% for 60Co and U, respectively. The data provide evidence that chemically reactive plasma treatment is available as a gas-phase decontamination method that can be conducted using nontoxic gases under safe and mild conditions such as reduced pressure, shorter time periods, and ambient temperature. Finally, a fluoric chemical reaction can be used to remove solid U deposits by converting them to gaseous U compounds at room temperature and without using plasma treatment. The pressure of ClF3 gradually affects the higher removal efficiency of U, and the removal efficiency is >90% under the conditions of 30 min and >100 Torr. The results verify that chemical reactions involving carbonylation and fluorination reactions can be utilized for gas-phase decontamination, and the potential for this new idea for decontamination is affirmed.If gas-phase decontamination technology is further developed, it will be not only convenient but also economically advantageous because decontaminating and treating the large volume of nuclear wastes - especially nonincinerable radioactive wastes - are currently very difficult.
