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To monitor radioactivity and its emissions in retired nuclear facilities, this study established an analytical method for 63 Ni and 55 Fe in mixed soil samples from a decommissioning reactor. After ashing at 400 °C for 4 hours, the sample was dissolved in a mixture of concentrated hydrochloric acid, nitric acid, and hydrofluoric acid, and then heated to dryness and dissolved in 9 mol/L hydrochloric acid. Subsequently, 63Ni and 63Fe were separated and purified using sodium hydroxide precipitation, anon exchange chromatography, and nickel specific rein extraction, and then measured by the liquid scintillation method. The results showed that the final stable recovery rates of Ni and Fe were 98.8% and 95.8%, respectively. The minimum detection limit and minimum detectable activity for 63Ni and 55Fe were 208 (counting) and 0.041 Bq,208 (counting) and 0.144 Bq, respectively. The actual activity concentrations of 63Ni and 55Fe in the samples were 76.9 Bq/g and 30.4 Bq/g, respectively. The recovery simulation experiment was conducted using standard soil substances, achieving a recovery of over 95%. Experiments were conducted on the separation of Ni and Fe from various elements using alkali precipitation and anon exchange chromatography, respectively. Among them, the sodium hydroxide precipitation method effectively coprecipitated Ni and Fe, and removed most of Re,Sr, and all Cs at pH value between 8.7 and 11.1. The decontamination factors for Co,Fe, and Zn in the nickel fraction of anion exchange chromatography were all above 660, wide the decontamination factors for Co,Eu,Mn,Ni, Sr,Zn, and Zr in the iron fraction were all above 2 000. This work also investigated the purification effects of DMG precipitation method and nickel specific resin method on Ni, respectively. The recovery of Ni by DMG precipitation method was 87.14%, and the recovery of Ni by nickel resin method was close to 100% when the nickel interference element ratio was above 10:1. Moreover, the purification effect of interference elements such as Ba, Eu, Fe, Mn, and Sr was the best. Therefore, before using nickel resin, other methods such as alkali precipitation and ion exchange resin should be used for preliminary separation. This method is simple to operate and has a high recovery, which can meet the needs of monitoring 63Ni and 55Fe in retired nuclear facilities. [ABSTRACT FROM AUTHOR]

The measurement of 55Fe and 63Ni is of great significance for the monitoring of liquid effluents from nuclear power plant. In this paper, a combined analysis method of 55Fe and 63Ni in liquid effluent sample is established. 55Fe and 63Ni are enriched by precipitation of iron hydroxide and nickel hydroxide and separated by TRU resin and nickel resin, then measured by low-level liquid scintillation spectrometer. Also the relevant measurement conditions are analyzed and studied. When the amount of sample is 1.0 L and the measurement time is 60 min, the detection lower limit of this method is 0.06 Bq/L for 55Fe and 0.02 Bq/L for 63Ni, which meets the analysis requirements of 55Fe and 63Ni in liquid effluents of nuclear power plant.

BackgroundThe energy deposition behavior of β particles in transducer material is an important issue in the simulation of a betavoltaic battery, which is usually performed by Monte Carlo software Casino and MCNP (Monte Carlo N Particle Transport Code). However, it is difficult to simulate the continuous energy spectrum of β particles by Casino software. The commercial software MCNP is subject to many restrictions on its copyright, it is very necessary to study the energy deposition of β particles in transducer materials based on the universal open-source Monte Carlo program Geant4 (GEometry ANd Tracking, version 4).PurposeThis study aims to develop a model based on Geant4 to study the energy deposition of β particles in betavoltaic battery transducer materials.MethodsBased on the framework of Geant4 software, a general simulation model of energy deposition behavior was developed. The continuous β spectrum, the self-absorption of radioactive source, and the backscattering of β particles on the source-transducer interface were taken into account completely in this model for the Monte-Carlo simulation study, and the computation results were compared with that of Casino software.ResultsSimulation comparison results show that this simulation model can accurately simulate the energy deposition behavior of β particles in the transducer materials of betavoltaic battery.ConclusionsSimulation model proposed in this study can be used to study the energy deposition of β particles in the transducer materials with advantages of convenient application, open software and easy extension to other source-transducer combinations.