CN-117248115-B - Process flow for integrally extracting strontium and americium from high-level radioactive waste liquid

Abstract

The invention relates to the technical field of nuclear chemical industry, in particular to a process flow for integrally extracting strontium and americium from high-level radioactive waste liquid. The invention uses N, N, N' -tetraoctyl-3-oxaglutaramide (TODGA) as an extractant, and provides a new liquid-liquid extraction process flow with two cycles, wherein the flow comprises strontium extraction cycle and americium extraction, and strontium and americium can be simultaneously extracted from high-level waste liquid. The process flow comprises two process links of americium extraction circulation and strontium extraction circulation, wherein the americium extraction circulation sequentially comprises three process steps of extracting americium, washing americium and back-extracting americium, and the strontium extraction circulation sequentially comprises three process steps of extracting strontium, washing strontium and back-extracting strontium.

Inventors

• WANG JIAN
• Dai Yunshui
• Chai Youqi
• HE NANLING
• NONG SHUYING
• YANG ANBO
• LI LIANSHUN
• Zhao Qiaozi
• XUE YONG
• LIU CAIBING
• MOU LING
• SHI XIUGAO

Assignees

• 中核四0四有限公司
• 中核四0四成都核技术工程设计研究院有限公司

Dates

Publication Date

20260508

Application Date

20230921

Claims (4)

1. 1. The process flow for integrally extracting strontium and americium from high-level radioactive waste liquid is characterized by comprising the following steps of: (S1) extracting the high-level radioactive waste liquid by using a TODGA-TBP-kerosene extraction system to obtain a first organic phase and a first aqueous phase; wherein the first organic phase contains americium, lanthanoid elements and part of the split elements, and the first aqueous phase contains strontium, cesium, iron, ruthenium and molybdenum elements; (S2) washing the first organic phase obtained in the step (S1) by sequentially using a high-acid solution containing oxalic acid and a low-acid solution to remove part of lanthanide and lobe impurity elements, and then back-extracting the first organic phase by using SO 3 -Ph-BTP to obtain a second organic phase and a second aqueous phase; The lanthanide is left in the second organic phase, so as to realize the extraction of the americium; (S3) extracting the first aqueous phase using a TODGA-TBP-kerosene extraction system to obtain a third organic phase comprising strontium and a third aqueous phase comprising split impurity elements; (S4) washing the third organic phase obtained in the step (S3) by using nitric acid, and then back-extracting the third organic phase by using a back-extracting agent to obtain an extract containing strontium, thereby realizing the extraction of strontium; the TODGA-TBP-kerosene extraction system is obtained by uniformly mixing TODGA, TBP and kerosene; In the step (S1), in the TODGA-TBP-kerosene extraction system, the concentration of TODGA is 0.03 mol/L-0.08 mol/L, the concentration of TBP is 0.3 mol/L-0.6 mol/L, and the volume ratio of the TODGA-TBP-kerosene extraction system to the high-level waste liquid is 1:1-1:3; In the step (S2), the volume ratio of the oxalic acid-containing high-acid solution to the first organic phase is 1:1-3:1, the volume ratio of the oxalic acid-containing low-acid solution to the first organic phase is 1:1-3:1, and the volume ratio of the SO 3 -Ph-BTP to the first organic phase is 1:1-1:1.5; In the step (S3), in the TODGA-TBP-kerosene extraction system, the concentration of TODGA is 0.2 mol/L-0.35 mol/L, the concentration of TBP is 0.4 mol/L-0.6 mol/L, and the volume ratio of the TODGA-TBP-kerosene extraction system to the first water phase is 1:1-1:3; In the step (S4), the stripping agent is selected from one of disodium ethylenediamine tetraacetate, citric acid or diethyl triamine pentaacetic acid, and the volume ratio of the stripping agent to the third organic phase is 1:1-1:3.
2. 2. The process flow for integrally extracting strontium and americium from high-level spent liquor according to claim 1, wherein in the step (S1), the high-level spent liquor is generated in a process of post-treating PUREX spent fuel, and the concentration of nitric acid is 2.5 mol/L to 4 mol/L.
3. 3. The process for integrally extracting strontium and americium from high-level waste liquid according to claim 1, wherein in the step (S2), the oxalic acid-containing high-acidity solution comprises 0.1 mol/L to 0.5 mol/L oxalic acid and 2 mol/L to 3 mol/L nitric acid; The components of the low-acidity solution are nitric acid solution with the concentration of 0.4 mol/L-0.8 mol/L; The concentration of SO 3 -Ph-BTP is 0.01 mol/L-0.05 mol/L, and the concentration of the environmental nitric acid of SO 3 -Ph-BTP is 0.2 mol/L-0.8 mol/L.
4. 4. The process for integrally extracting strontium and americium from high-level radioactive waste liquid according to claim 1, wherein in the step (S4), the concentration of nitric acid is 0.8 mol/L to 1.0mol/L; the volume ratio of the nitric acid to the third organic phase is 1:1-1:3.

Description

Process flow for integrally extracting strontium and americium from high-level radioactive waste liquid Technical Field The invention relates to the technical field of nuclear chemical industry, in particular to a process flow for integrally extracting strontium and americium from high-level radioactive waste liquid. Background After the spent fuel is treated by the PUREX process, a highly radioactive and highly acidic high-emission waste liquid (HLLW) is produced, and the spent fuel has complex components and contains minor actinides (americium, curium and the like) and splinters (strontium, cesium, lanthanoid, zirconium, molybdenum, palladium, iron and the like). However, some radionuclides in the elements contained in the high-level radioactive waste liquid have high application value and can be used in the fields of military, medical treatment and the like. Strontium-90 (90 Sr) is a nuclear species of pure beta-emitter, whose decay daughter yttrium-90 is an important source of radiation for medical treatment. Meanwhile, strontium-90 is a high-heat nuclide which is used as a heat source of a nuclear battery and is used as a nuclear battery energy source in deep sea exploration and severe environment areas. Americium-241/243 is an alpha source and may be used in thickness gauges, level gauges, thermometers, ion smoke detectors, and artificial elemental target materials. The extraction of strontium-90 and americium-241/243 from high level radioactive waste solutions is a precondition for fully utilizing the economic value thereof. However, the difficulty in separating and extracting strontium and americium from the high-level waste liquid is very high due to the complex components of the high-level waste liquid. Americium extraction studies are currently the technology of interest in many countries, france using DMDBTDMA or DMDOHEMA as the extractant, developing DIAMEX extraction schemes, usa using T2EHDGA to extract lanthanides and actinides, and then DTPA lanthanides and actinides to obtain americium products, japan, india and usa studies on the use of N, N' -tetraoctyl-3-oxaglutaramide (TODGA) as the extractant to obtain americium. The technical research on strontium extraction mainly focuses on the extraction separation of crown ether type extractant and bisamide pod ether type extractant. Although there is currently a great deal of research related to the extraction of strontium and americium, most of the technologies remain only in the basic research stage and have not been successfully industrialized. In order to realize the extraction of strontium and americium, a process which is simple in process, easy to obtain reagents and high in industrial feasibility is designed, the extraction of strontium and americium is realized in the same process, the complexity of the reagents is reduced, the engineering difficulty is reduced, and the method has important significance for the current extraction of strontium and americium. Disclosure of Invention In order to solve the problems, the invention aims to provide a process flow for integrally extracting strontium and americium from high-level radioactive waste liquid. The invention uses N, N, N' -tetraoctyl-3-oxaglutaramide (TODGA) as an extractant, and provides a new liquid-liquid extraction process flow with two cycles, wherein the flow comprises strontium extraction cycle and americium extraction, and strontium and americium can be simultaneously extracted from high-level waste liquid. The process flow comprises two process links of americium extraction circulation and strontium extraction circulation, wherein the americium extraction circulation sequentially comprises three process steps of extracting americium, washing americium and back-extracting americium, and the strontium extraction circulation sequentially comprises three process steps of extracting strontium, washing strontium and back-extracting strontium. The aim of the invention can be achieved by the following technical scheme: the invention provides a process flow for integrally extracting strontium and americium from high-level radioactive waste liquid, which comprises the following steps: (S1) extracting the high-level radioactive waste liquid by using a TODGA-TBP-kerosene extraction system to obtain a first organic phase and a first aqueous phase; wherein the first organic phase contains americium, lanthanoid elements and part of the split elements, and the first aqueous phase contains strontium, cesium, iron, ruthenium and molybdenum elements; (S2) washing the first organic phase obtained in the step (S1) by sequentially using a high-acid solution containing oxalic acid and a low-acid solution to remove part of lanthanide and lobe impurity elements, and then back-extracting the first organic phase by using SO 3 -Ph-BTP to obtain a second organic phase and a second aqueous phase; The lanthanide is left in the second organic phase, so as to realize the extraction of the americium; (S3) ext