Burnup Of Minor Actinides Transmutation In The Lead-Cooled Fast Reactor

With the development of nuclear power,the production of spent fuel is increasing.How to deal with spent fuel effectively has become one of the key factors restricting the development of nuclear power.The separation-transmutation scheme is currently considered to be the best solution to reduce long-term radioactive hazards.The separation-transmutation scheme is based on the existing post-treatment cycle scheme,separating the minor actinides(MA)and long-lived fission products from the high-level liquid waste and transforming them into short-life,stable or high value nuclides through reactor transmutation.In this paper,the transmutation characteristics and bumup of MA in lead-cooled fast reactor are studied.And the contents of the study are as follows:Three different MA loading schemes are designed in this paper.The first one i5 the mixing of MA and MOX fuel homogeneously.The second one is to make MA into transmutation rods and replace part of the fuel rods in the core.And the third one is to use MA as fuel coating.Firstly,the effects of 1 wt%MA loading on core keff,control rod integral value,neutron energy spectrum and power peak factor are studied.Then,the influence of different MA mass loading on keff of core is calculated and analyzed to determine the maximum MA mass loading of subsequent studies.Finally,the bumup of MA in the lead-cooled fast reactor is studied.In this paper,MCNP and SCALE programs are used to build and calculate the core.Calculation and analysis show that,after loading 1 wt%MA,three loading modes are all making the control rod integral value reduced.Among them,uniform mixing and MA coating modes decrease slightly,while transmutation rod modes decrease greatly.Introducing 1 wt%MA in the three loading modes will not have a significant impact on the neutron energy spectrum in the core;and compared with the loading pattern without MA,the power peak factor of the three loading modes is slightly reduced,and the power distribution has not ehanged significantly,which is a significant advantage of the transmutation MA in the lead-cooled fast reactor.The initial keff of core decreases with the increase of MA loading no matter which loading mode,and the coating way has the greatest impact on keff and the transmutation rod loading mode has the least impact because of the effect of space self-shielding effect.The bumup of MA in lead-cooled fast reactor shows,although the keff of the core decreases with the increase of MA loading at the initial stage of operation,however,238Pu,239Pu,242Am,244Am,243Cm and 245Cm which have larger fission cross-sections are produced after MA absorbing neutrons during operation,which compensate for the initial reduction of keff,thus extending the core life.The transmutation rate of MA in lead-cooled fast reactor shows,after 550 days of irradiation,the transmutation rate of mixing homogeneously and coating MA loading modes decreases with the increase of loading mass.Due to the fact that the transmutation rate of transmutation rod loading way is affected by the loading position of MA,there is no obvious regularity with the increase of loading mass.Under the same loading mass,the transmutation rate of coating loading mode is the highest.When 3 wt%MA is loaded,the total transmutation rate is still above 25%.Comparing the transmutation of different MA nuclides,the mass of 237Np,241Am and 243Am decreases with the increase of irradiation time,241 Am has the highest transmutation rate,while that of 244Cm and 245Cm increase.The increase of 245Cm is the greatest,but 245Cm has larger fission cross section and can be used as nuclear fuel.