The temperature dependence of the ultrasonic parameters like ultrasonic velocities and Grüneisen parameters in americium monopnictides AmY (Y: N, P, As, Sb and Bi) have been studied for longitudinal and shear wav...The temperature dependence of the ultrasonic parameters like ultrasonic velocities and Grüneisen parameters in americium monopnictides AmY (Y: N, P, As, Sb and Bi) have been studied for longitudinal and shear waves along , and crystallographic directions in the temperature range 100 K - 500 K. The second- and third- order elastic constants have also been evaluated for these monopnictides using Coulomb and Born-Mayer potential. The values of elastic constants are the highest for AmN. Hence the mechanical properties of AmN are better than other monopnictides AmP, AmAs, AmSb and AmBi. Ultrasonic velocity is found large for AmP. So the ultrasonic wave propagation will be much better than others in AmP. Obtained results are compared with available results of same type of materials.展开更多
One of the postponed problems of nuclear power (NP) is the problem of the management of long-lived radioactive waste (RAW), and, first of all, with minor actinides (MA), of which americium-241 is the most difficult. T...One of the postponed problems of nuclear power (NP) is the problem of the management of long-lived radioactive waste (RAW), and, first of all, with minor actinides (MA), of which americium-241 is the most difficult. The aim of this work is to study the efficiency of americium transmutation in a fast reactor with a heavy liquid metal coolant lead-bismuth eutectic alloy. The article presents the results of calculations of the transmutation of americium in the SVBR-100 reactor using standard uranium oxide fuel with the addition of americium-241. The obtained values of the rate of transmutation of americium are compared with similar values for the SVBR-100 reactors on MOX-fuel and in the BN-800 reactor.展开更多
The extraction behavior of bis (2,4,4-trimethylpentyl) dithiophosphinic acid (HBTMPDTP), purified from Cyanex 301, was studied for extracting Am 3+ and trivalent lanthanides (Lns). HBTMPDTP shows very high selectivity...The extraction behavior of bis (2,4,4-trimethylpentyl) dithiophosphinic acid (HBTMPDTP), purified from Cyanex 301, was studied for extracting Am 3+ and trivalent lanthanides (Lns). HBTMPDTP shows very high selectivity for Am. Separation factor (SF) of Am and Eu, SF Am/Eu ,(trace amount) reaches a high value of 5.9×10 3 and SF Am/(Pr+Nd) (macro amount) is about 2×10 3. The mathematical model for the distribution ratios and process parameters calculated for HBTMPDTP extraction was established and the calculated results were verified experimentally. In a five-stage countercurrent process, the extraction rates of Am and Lns were > 99.999% and 0.14%, respectively, to fulfill the separation requirements. The efficiency of this process was also verified in a cross-flow extraction experiment using a genuine Am-FPLns fraction. In the presence of TBP, the extraction of Am and Eu is enhanced, but their separation is reduced to some extent. A fairly good separation was achieved in a fractional extraction process using a mixture of HBTMPDTP and TBP in kerosene at low pH.展开更多
We reported the synthesis,single crystal structure,and solid-state UV-Vis-NIR spectroscopy of a new transplutonium metal-organic framework(MOFs),Am(H_(2)O)[PO[(C6H4)COO]_(3)],denoted as AmTPO(TPO=tris(4-carboxylphenyl...We reported the synthesis,single crystal structure,and solid-state UV-Vis-NIR spectroscopy of a new transplutonium metal-organic framework(MOFs),Am(H_(2)O)[PO[(C6H4)COO]_(3)],denoted as AmTPO(TPO=tris(4-carboxylphenyl)-phosphineoxide).AmTPO forms a three-dimensional metal-organic framework structure with americium dimers as the secondary building unit.Clear 5f→5f transi-tions attributed to trivalent americium was observed in the absorption spectrum of AmTPO ranging from 300 to 1200 nm.Notably,AmTPO can maintain the crystallinity with no observable structural degradation within several months after being synthesized,re-vealing a long-term radiation resistance of this structure and the potential application of MOFs as a platform for nuclear waste dis-posal.展开更多
Separation of the minor actinides(Am and Cm)from lanthanides in high-level liquid wastes(HLLW)is one of the most challenging chemical separation tasks known owing to their chemical similarities and is highly significa...Separation of the minor actinides(Am and Cm)from lanthanides in high-level liquid wastes(HLLW)is one of the most challenging chemical separation tasks known owing to their chemical similarities and is highly significant in nuclear fuel reprocessing plants because it could practically lead to sustainable nuclear energy by closing the nuclear fuel cycle.The solid phase extraction is proposed to be a possible strategy but all reported sorbent materials severely suffer from limited stability and/or efficiency caused by the harsh conditions of high acidity coupled with intense irradiation.Herein,a phenanthroline-based polymeric organic framework(PhenTAPB-POF)was designed and tested for the separation of trivalent americium from lanthanides for the first time.Due to its fully conjugated structure,PhenTAPB-POF exhibits previously unachieved stability under the combined extreme conditions of strong acids and high irradiation field.The americium partitioning experiment indicates that PhenTAPB-POF possesses an ultrahigh adsorption selectivity towards Am(Ⅲ)over lanthanides(e.g.,SFAm(Ⅲ)/Eu(Ⅲ)=3326)in highly acidic simulated HLLW and relatively fast adsorption kinetics in both static and dynamic experiments.Am(Ⅲ)can be almost quantitatively eluted from the PhenTAPB-POF packed-column using a concentrated nitric acid elution.The high stability and superior separation performance endow PhenTAPB-POF with the promising alternative for separating minor actinides over lanthanides from highly acidic HLLW streams.展开更多
The numerical calculations for Am multistage fractional extraction by trialkyl phosphine oxide (TRPO) were verified by a hot test. 1750L/t-U high level waste (HLW) was used as the feed to the TRPO process. The analysi...The numerical calculations for Am multistage fractional extraction by trialkyl phosphine oxide (TRPO) were verified by a hot test. 1750L/t-U high level waste (HLW) was used as the feed to the TRPO process. The analysis used the simple objective function to minimize the total waste content in the TRPO process streams. Some process parameters were optimized after other parameters were selected. The optimal process parameters for Am extraction by TRPO are: 10 stages for extraction and 2 stages for scrubbing; a flow rate ratio of 0.931 for extraction and 4.42 for scrubbing; nitric acid concentration of 1.35mol/L for the feed and 0.5mol/L for the scrubbing solution. Finally, the nitric acid and Am concentration profiles in the optimal TRPO extraction process are given.展开更多
In recent years, a great deal of interest has been focused on nitrogen-containing extractants for the separation of actinides from lanthanides. In this study, we synthesized a polyazamacrocycle-type C8-cyclen ligand c...In recent years, a great deal of interest has been focused on nitrogen-containing extractants for the separation of actinides from lanthanides. In this study, we synthesized a polyazamacrocycle-type C8-cyclen ligand comprising four tertiary alkyl amino groups, for the extraction of Am3+ and Eu3+. The C8-cyclen demonstrated a weak ability to extract and separate Am3+ and Eu3+ that increased with the increasing "softness" of the aqueous anions. The extraction behavior of Am3+ and Eu3+ indicated coordination interactions between the C8-cyclen and the Am3+ and Eu3+ ions. The suppression of Am3+ or Eu3+ extraction by acid depended on the media anions involved.展开更多
文摘The temperature dependence of the ultrasonic parameters like ultrasonic velocities and Grüneisen parameters in americium monopnictides AmY (Y: N, P, As, Sb and Bi) have been studied for longitudinal and shear waves along , and crystallographic directions in the temperature range 100 K - 500 K. The second- and third- order elastic constants have also been evaluated for these monopnictides using Coulomb and Born-Mayer potential. The values of elastic constants are the highest for AmN. Hence the mechanical properties of AmN are better than other monopnictides AmP, AmAs, AmSb and AmBi. Ultrasonic velocity is found large for AmP. So the ultrasonic wave propagation will be much better than others in AmP. Obtained results are compared with available results of same type of materials.
文摘One of the postponed problems of nuclear power (NP) is the problem of the management of long-lived radioactive waste (RAW), and, first of all, with minor actinides (MA), of which americium-241 is the most difficult. The aim of this work is to study the efficiency of americium transmutation in a fast reactor with a heavy liquid metal coolant lead-bismuth eutectic alloy. The article presents the results of calculations of the transmutation of americium in the SVBR-100 reactor using standard uranium oxide fuel with the addition of americium-241. The obtained values of the rate of transmutation of americium are compared with similar values for the SVBR-100 reactors on MOX-fuel and in the BN-800 reactor.
文摘The extraction behavior of bis (2,4,4-trimethylpentyl) dithiophosphinic acid (HBTMPDTP), purified from Cyanex 301, was studied for extracting Am 3+ and trivalent lanthanides (Lns). HBTMPDTP shows very high selectivity for Am. Separation factor (SF) of Am and Eu, SF Am/Eu ,(trace amount) reaches a high value of 5.9×10 3 and SF Am/(Pr+Nd) (macro amount) is about 2×10 3. The mathematical model for the distribution ratios and process parameters calculated for HBTMPDTP extraction was established and the calculated results were verified experimentally. In a five-stage countercurrent process, the extraction rates of Am and Lns were > 99.999% and 0.14%, respectively, to fulfill the separation requirements. The efficiency of this process was also verified in a cross-flow extraction experiment using a genuine Am-FPLns fraction. In the presence of TBP, the extraction of Am and Eu is enhanced, but their separation is reduced to some extent. A fairly good separation was achieved in a fractional extraction process using a mixture of HBTMPDTP and TBP in kerosene at low pH.
基金supported by grants from the National Natural Science Foundation of China(21825601,21790374,21906113,21727801)a Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)。
文摘We reported the synthesis,single crystal structure,and solid-state UV-Vis-NIR spectroscopy of a new transplutonium metal-organic framework(MOFs),Am(H_(2)O)[PO[(C6H4)COO]_(3)],denoted as AmTPO(TPO=tris(4-carboxylphenyl)-phosphineoxide).AmTPO forms a three-dimensional metal-organic framework structure with americium dimers as the secondary building unit.Clear 5f→5f transi-tions attributed to trivalent americium was observed in the absorption spectrum of AmTPO ranging from 300 to 1200 nm.Notably,AmTPO can maintain the crystallinity with no observable structural degradation within several months after being synthesized,re-vealing a long-term radiation resistance of this structure and the potential application of MOFs as a platform for nuclear waste dis-posal.
基金supported by the grants from the National Natural Science Foundation of China(Nos.21825601,21790374,and 21806117)。
文摘Separation of the minor actinides(Am and Cm)from lanthanides in high-level liquid wastes(HLLW)is one of the most challenging chemical separation tasks known owing to their chemical similarities and is highly significant in nuclear fuel reprocessing plants because it could practically lead to sustainable nuclear energy by closing the nuclear fuel cycle.The solid phase extraction is proposed to be a possible strategy but all reported sorbent materials severely suffer from limited stability and/or efficiency caused by the harsh conditions of high acidity coupled with intense irradiation.Herein,a phenanthroline-based polymeric organic framework(PhenTAPB-POF)was designed and tested for the separation of trivalent americium from lanthanides for the first time.Due to its fully conjugated structure,PhenTAPB-POF exhibits previously unachieved stability under the combined extreme conditions of strong acids and high irradiation field.The americium partitioning experiment indicates that PhenTAPB-POF possesses an ultrahigh adsorption selectivity towards Am(Ⅲ)over lanthanides(e.g.,SFAm(Ⅲ)/Eu(Ⅲ)=3326)in highly acidic simulated HLLW and relatively fast adsorption kinetics in both static and dynamic experiments.Am(Ⅲ)can be almost quantitatively eluted from the PhenTAPB-POF packed-column using a concentrated nitric acid elution.The high stability and superior separation performance endow PhenTAPB-POF with the promising alternative for separating minor actinides over lanthanides from highly acidic HLLW streams.
基金the Major Research Project of the Ninth-Five Plan(1996 2 0 0 0 ) of China!(No:96 - A18- 0 2 - 0 1)
文摘The numerical calculations for Am multistage fractional extraction by trialkyl phosphine oxide (TRPO) were verified by a hot test. 1750L/t-U high level waste (HLW) was used as the feed to the TRPO process. The analysis used the simple objective function to minimize the total waste content in the TRPO process streams. Some process parameters were optimized after other parameters were selected. The optimal process parameters for Am extraction by TRPO are: 10 stages for extraction and 2 stages for scrubbing; a flow rate ratio of 0.931 for extraction and 4.42 for scrubbing; nitric acid concentration of 1.35mol/L for the feed and 0.5mol/L for the scrubbing solution. Finally, the nitric acid and Am concentration profiles in the optimal TRPO extraction process are given.
基金supported by the National Natural Science Foundation of China(91226110)the Program for Changjiang Scholars and Innovative Research Team in University
文摘In recent years, a great deal of interest has been focused on nitrogen-containing extractants for the separation of actinides from lanthanides. In this study, we synthesized a polyazamacrocycle-type C8-cyclen ligand comprising four tertiary alkyl amino groups, for the extraction of Am3+ and Eu3+. The C8-cyclen demonstrated a weak ability to extract and separate Am3+ and Eu3+ that increased with the increasing "softness" of the aqueous anions. The extraction behavior of Am3+ and Eu3+ indicated coordination interactions between the C8-cyclen and the Am3+ and Eu3+ ions. The suppression of Am3+ or Eu3+ extraction by acid depended on the media anions involved.
