摘要
A burnup calculation was performed to analyze the Apr`es ORIENT process, which aims to create highlyvaluable elements from fission products separated from spent nuclear fuels. The basic idea is to use nuclear transmutation induced by a neutron capture reaction followed by a β-decay, thus changing the atomic number Z of a target element in fission products by 1 unit. LWR(PWR) and FBR(MONJU) were considered as the transmutation devices. High rates of creation were obtained in some cases of platinum group metals(44Ru by FBR,46 Pd by LWR) and rare earth(64Gd by LWR,66 Dy by FBR). Therefore, systems based on LWR and FBR have their own advantages depending on target elements. Furthermore, it was found that creation rates of even Z(= Z + 1) elements from odd Z ones were higher than the opposite cases. This creation rate of an element was interpreted in terms of "average 1-group neutron capture cross section of the corresponding target element σc Z defined in this work. General trends of the creation rate of an even(odd) Z element from the corresponding odd(even) Z one were found to be proportional to the 0.78th(0.63th) power of σc Z, however with noticeable dispersion. The difference in the powers in the above analysis was explained by the difference in the number of stable isotopes caused by the even-odd effect of Z.
A burnup calculation was performed to analyze the Apres ORIENT process, which aims to create highlyvaluable elements from fission products separated from spent nuclear fuels. The basic idea is to use nuclear transmutation induced by a neutron capture reaction followed by α β- decay, thus changing the atomic number Z of a target element in fission products by 1 unit. LWR （PWR） and FBR （MONJU） were considered as the transmutation devices. High rates of creation were obtained in some cases of platinum group metals （44RH by FBR, 46Pd by LWR） and rare earth （64Gd by LWR, 66Dy by FBR）. Therefore, systems based on LWR and FBR have their own advantages depending on target elements. Furthermore, it was found that creation rates of even Z′ （= Z ＋ 1） elements from odd Z ones were higher than the opposite cases. This creation rate of an element was interpreted in terms of ＂average 1-group neutron capture cross section of the corresponding target element （σcz）″ defined in this work. General trends of the creation rate of an even （odd） Z′ element from the corresponding odd （even） Z one were found to be proportional to the 0.78th （0.63th） power of （σcz）, however with noticeable dispersion. The difference in the powers in the above analysis was explained by the difference in the number of stable isotopes caused by the even-odd effect of Z.
