The studies of thermal fission rates are relevant to novel reactors,astrophysical environments,and survival probabilities of compound superheavy nuclei.This has been conventionally studied by the Bohr-Wheeler statisti...The studies of thermal fission rates are relevant to novel reactors,astrophysical environments,and survival probabilities of compound superheavy nuclei.This has been conventionally studied by the Bohr-Wheeler statistical model that depends on phenomenological level densities and fission barriers.In this context,we propose to study the thermal fission rates based on microscopic temperature dependent nuclear energy density functional theory.The microscopic temperature dependent fission barrier heights and curvatures,and collective mass parameters can be self-consistently obtained.The fission lifetimes from low to high temperatures can be given by the imaginary free energy method in a consistent framework.Microscopic temperature dependent fission barriers play an essential role in fission studies.展开更多
To validate neutronics calculation for the blanket design of fusion-fission hybrid reactor,experiments for measuring reaction rates inside two simulating assemblies are performed.Two benchmark assemblies were develope...To validate neutronics calculation for the blanket design of fusion-fission hybrid reactor,experiments for measuring reaction rates inside two simulating assemblies are performed.Two benchmark assemblies were developed for the neutronics experiments.A D-T fusion neutron source is placed at the center of the setup.One of them consists of three layers of depleted uranium shells and two layers of polyethylene shells,and these shells are arranged alternatively.The ^(238)U capture reaction rates are measured using depleted uranium foils and an HPGe gamma spectrometer.The fission reaction rates are measured using a fission chamber coated with depleted uranium.The other assembly consists of depleted uranium and LiH shells.The tritium production rates are measured using the lithium glass scintillation detector which is placed in the LiH region of the assembly.The measured reaction rates are compared with the calculated ones predicted using MCNP code,and C/E values are obtained.展开更多
The fission rate of <sup>240</sup>Pu at its saddle point is obtained by using generalized coherentstate ansatz for large friction case. The numerical results indicate that the quasi-stationary fiss-ion rat...The fission rate of <sup>240</sup>Pu at its saddle point is obtained by using generalized coherentstate ansatz for large friction case. The numerical results indicate that the quasi-stationary fiss-ion rate approaches Kramers’ rate and the transient behaviour agrees with that given in previousstudies. Moreover, the relationship between the first eigenvalue λ<sub>1</sub> and the quasi-stationary fiss-ion rate λ<sub>qs</sub> is derived. In the case of high temperature, we also pay attention to the overshoot-ing.展开更多
文摘The studies of thermal fission rates are relevant to novel reactors,astrophysical environments,and survival probabilities of compound superheavy nuclei.This has been conventionally studied by the Bohr-Wheeler statistical model that depends on phenomenological level densities and fission barriers.In this context,we propose to study the thermal fission rates based on microscopic temperature dependent nuclear energy density functional theory.The microscopic temperature dependent fission barrier heights and curvatures,and collective mass parameters can be self-consistently obtained.The fission lifetimes from low to high temperatures can be given by the imaginary free energy method in a consistent framework.Microscopic temperature dependent fission barriers play an essential role in fission studies.
基金supported by the National Special Magnetic Confinement Fusion Energy Research (No.2010GB111002),China
文摘To validate neutronics calculation for the blanket design of fusion-fission hybrid reactor,experiments for measuring reaction rates inside two simulating assemblies are performed.Two benchmark assemblies were developed for the neutronics experiments.A D-T fusion neutron source is placed at the center of the setup.One of them consists of three layers of depleted uranium shells and two layers of polyethylene shells,and these shells are arranged alternatively.The ^(238)U capture reaction rates are measured using depleted uranium foils and an HPGe gamma spectrometer.The fission reaction rates are measured using a fission chamber coated with depleted uranium.The other assembly consists of depleted uranium and LiH shells.The tritium production rates are measured using the lithium glass scintillation detector which is placed in the LiH region of the assembly.The measured reaction rates are compared with the calculated ones predicted using MCNP code,and C/E values are obtained.
文摘The fission rate of <sup>240</sup>Pu at its saddle point is obtained by using generalized coherentstate ansatz for large friction case. The numerical results indicate that the quasi-stationary fiss-ion rate approaches Kramers’ rate and the transient behaviour agrees with that given in previousstudies. Moreover, the relationship between the first eigenvalue λ<sub>1</sub> and the quasi-stationary fiss-ion rate λ<sub>qs</sub> is derived. In the case of high temperature, we also pay attention to the overshoot-ing.
