MIXED Oxide Nuclear fuel (MOX) contains both uranium and plutonium in oxidized form. It is important to calculate the nuclear decay heat due to the single thermal fission (fission due to 0.0235 eV neutron) for all fis...MIXED Oxide Nuclear fuel (MOX) contains both uranium and plutonium in oxidized form. It is important to calculate the nuclear decay heat due to the single thermal fission (fission due to 0.0235 eV neutron) for all fissile nuclei in the MOX fuels (U<sup>235</sup>, Pu<sup>239</sup>, and Pu<sup>241</sup>). These fissile nuclei are the main source of the decay heat in MOX fuel. Decay heat calculation of the weighted fissile material content in MOX fuel is also important. A numerical method was used in this work to calculate the concentrations of all fission products due to the individual thermal fission of the three fissile materials as a function of time N(t). The decay heat calculations for the three fissile materials are directly calculated using the summation method by knowing the different concentrations of fission products over time. The average decay heat of the MOX fuel in induced thermal fission is also concluded. The most influential nuclei in the decay heat were also identified. The method used has been validated by several comparisons before, but the new in this work is using the most recent Evaluated Nuclear Data Library ENDF/B-VIII.0. Calculations of decay heat show very common trends for a period of 10<sup>7</sup> sec after the fission burst of thermal fissions of individual fissile nuclei. Moreover, the code showed high capability in calculating the fission fragments inventories and decay heats due to the decay of fission fragments of 31 fissionable nuclei.展开更多
In this paper, a home-made code was designed to calculate the decay heat emitted by fission fragments as a result of successive radioactive emissions after a fission burst. The nuclear data necessary for the calculati...In this paper, a home-made code was designed to calculate the decay heat emitted by fission fragments as a result of successive radioactive emissions after a fission burst. The nuclear data necessary for the calculations was extracted from the latest version of the Evaluated Nuclear Data Library ENDF/B-VIII.0. The code can calculate the decay heat of thermal and fast neutron-induced fission reactions on the isotopes of Thorium, Protactinium, Uranium, Neptunium, Plutonium, Americium, Curium, California, Einsteinium, and Fermium. A numerical method was used in this work to calculate the decay heat of all fission fragments due to the individual thermal or fast fissions of the isotopes of the previous ten actinides. The most influential nuclei in the decay heat were also identified at different times after the fission event. Moreover, the code showed high capability in calculating the fission fragments inventories and decay heats due to the decay of fission fragments of 31 fissionable nuclei.展开更多
The natural radioactivity of 226Ra, 232Th and 40K and the fallout of 137Cs in soils and granite rocks of two regions in Yemen (Shabwah and Hadramout) were measured by using gamma-ray spectrometry (HPGe) detector. The ...The natural radioactivity of 226Ra, 232Th and 40K and the fallout of 137Cs in soils and granite rocks of two regions in Yemen (Shabwah and Hadramout) were measured by using gamma-ray spectrometry (HPGe) detector. The average values of the radionuclides 226Ra, 232Th and 40K in the soil samples are 14.34, 25.78 and 566.05 Bq/kg respectively. For rock samples, the average activity concentration for 226Ra, 232Th and 40K are 45, 106 and 1235 Bq/kg respectively. Low concentration values of 137Cs in soil and rock samples under investigation, are not radiologically important. The radium equivalent activity (Raeq) and external hazard index (Hex) of all samples are less than the limits of 370 Bq·kg-1 and unity, respectively. The average values of total absorbed dose rate due to three primordial radionuclides in soil and rock samples are 46.5 nGy/h and 138.36 nGy/h, respectively, where the absorbed average value of the granite is higher than the permitted limit. So, the local people must avoid using these granite samples as the interior decorative materials of dwelling without radioactivity control.展开更多
文摘MIXED Oxide Nuclear fuel (MOX) contains both uranium and plutonium in oxidized form. It is important to calculate the nuclear decay heat due to the single thermal fission (fission due to 0.0235 eV neutron) for all fissile nuclei in the MOX fuels (U<sup>235</sup>, Pu<sup>239</sup>, and Pu<sup>241</sup>). These fissile nuclei are the main source of the decay heat in MOX fuel. Decay heat calculation of the weighted fissile material content in MOX fuel is also important. A numerical method was used in this work to calculate the concentrations of all fission products due to the individual thermal fission of the three fissile materials as a function of time N(t). The decay heat calculations for the three fissile materials are directly calculated using the summation method by knowing the different concentrations of fission products over time. The average decay heat of the MOX fuel in induced thermal fission is also concluded. The most influential nuclei in the decay heat were also identified. The method used has been validated by several comparisons before, but the new in this work is using the most recent Evaluated Nuclear Data Library ENDF/B-VIII.0. Calculations of decay heat show very common trends for a period of 10<sup>7</sup> sec after the fission burst of thermal fissions of individual fissile nuclei. Moreover, the code showed high capability in calculating the fission fragments inventories and decay heats due to the decay of fission fragments of 31 fissionable nuclei.
文摘In this paper, a home-made code was designed to calculate the decay heat emitted by fission fragments as a result of successive radioactive emissions after a fission burst. The nuclear data necessary for the calculations was extracted from the latest version of the Evaluated Nuclear Data Library ENDF/B-VIII.0. The code can calculate the decay heat of thermal and fast neutron-induced fission reactions on the isotopes of Thorium, Protactinium, Uranium, Neptunium, Plutonium, Americium, Curium, California, Einsteinium, and Fermium. A numerical method was used in this work to calculate the decay heat of all fission fragments due to the individual thermal or fast fissions of the isotopes of the previous ten actinides. The most influential nuclei in the decay heat were also identified at different times after the fission event. Moreover, the code showed high capability in calculating the fission fragments inventories and decay heats due to the decay of fission fragments of 31 fissionable nuclei.
文摘The natural radioactivity of 226Ra, 232Th and 40K and the fallout of 137Cs in soils and granite rocks of two regions in Yemen (Shabwah and Hadramout) were measured by using gamma-ray spectrometry (HPGe) detector. The average values of the radionuclides 226Ra, 232Th and 40K in the soil samples are 14.34, 25.78 and 566.05 Bq/kg respectively. For rock samples, the average activity concentration for 226Ra, 232Th and 40K are 45, 106 and 1235 Bq/kg respectively. Low concentration values of 137Cs in soil and rock samples under investigation, are not radiologically important. The radium equivalent activity (Raeq) and external hazard index (Hex) of all samples are less than the limits of 370 Bq·kg-1 and unity, respectively. The average values of total absorbed dose rate due to three primordial radionuclides in soil and rock samples are 46.5 nGy/h and 138.36 nGy/h, respectively, where the absorbed average value of the granite is higher than the permitted limit. So, the local people must avoid using these granite samples as the interior decorative materials of dwelling without radioactivity control.
