RADIATION PROTECTION

The latest evaluation on exposure levels to ionizing radiation from the United Nations Scientific Committee on the Effects of Atomic Radiation

CHEN Jing

RADIATION PROTECTION. 2026, 46(4): 285-292. doi:10.27045/j.1000-8187.202604001

Abstract ( 38 )

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Since 1958,the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) has regularly and repeatedly evaluated the levels of medical, occupational, and public exposures to ionizing radiation from both natural and artificial sources, and the exposure trends over time. UNSCEAR’s evaluations provide an independent, objective and up to date scientific basis for radiation safety. Countries and international organizations draw on the UNSCEAR’s scientific evaluations for developing protection programmes, legal instruments and policies for using technologies employing ionizing radiation. This article briefly summarizes the latest UNSCEAR evaluations on medical, occupational, and public exposure to ionizing radiation, and elaborates on the importance of full participation of United Nations member states in future UNSCEAR radiation level surveys and assessments.

A study on the construction method of reporting level system forenvironmental radiation monitoring at nuclear power plants

HUANG Yanjun, JIANG Jin, CAO Zhonggang, ZHAO Feng

RADIATION PROTECTION. 2026, 46(4): 293-302. doi:10.27045/j.1000-8187.202604002

Abstract ( 28 )

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Establishing a scientific environmental radiation monitoring reporting level system is a crucial step in enhancing the effectiveness of radiation environmental regulation for nuclear power plants. This paper systematically reviews the theoretical foundations of the reporting level for environmental radiation monitoring and investigates the relevant institutional practices in countries including the United States and France, as well as Taiwan Region of China. Based on an analysis of the dose contributions from various exposure pathways to the critical group around major nuclear power plants in China, an attempt is made to allocate the total dose management objective of 0.25 mSv/a to individual pathways. Consequently, preliminary recommendations for reporting level values for key radionuclides, including ⁶⁰Co, ¹³⁷Cs, and ³H, in environmental media such as air, water, soil, and biota. Furthermore, the research constructs a closed-loop management system of “monitoring-assessment-triggering-action”, aiming to provide methodological reference and a preliminary technical scheme for improving the quantification and precision of environmental radiation quality assessment and regulation in China.

Phase transformation mechanism and long-term leaching behavior ofhydrothermally synthesized pollucite for radioactive cesium immobilization

YU Weiyue, WANG Longjiang, GU Weigang, LIU Yifei, KONG Xiangyin, GAO Chao, YAN Xiaojun, GAO Kai, LI Xiaodong

RADIATION PROTECTION. 2026, 46(4): 303-312. doi:10.27045/j.1000-8187.202604003

Abstract ( 26 )

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Safe disposal of cesium nuclides in high-level radioactive liquid waste is a critical challenge in the back-end of the nuclear fuel cycle. Pollucite possesses a unique three-dimensional cage framework and excellent chemical durability, making it an ideal mineral matrix for immobilizing radioactive cesium. In this work, high-purity pollucite crystals were successfully synthesized via a low-temperature hydrothermal method. Combined with two characterization techniques, including full-profile Rietveld refinement of X-ray powder diffraction (XRD) and micro-Raman spectroscopy, the phase transformation kinetics and microstructural evolution mechanism of pollucite were systematically investigated. The experimental results reveal that the crystallization of pollucite follows a dissolution-recrystallization mechanism. As a vital structure-directing agent, cesium ion drives the continuous dissolution of sodium-rich metastable phases, which are completely converted into pure-phase pollucite after 60 hours of reaction. Meanwhile, the variation of intrinsic characteristic peaks in the low-frequency region of Raman spectra confirms that cesium ion is successfully immobilized within the cage pores of pollucite. Furthermore, a dual kinetic reservoir model coupled with Python and PHREEQC was established. This model effectively distinguishes the initial rapid leaching behavior of unstable phases on the material surface and accurately determines the long-term intrinsic steady-state leaching rate of the solidified form, which is approximately 3.16×10^-8g·m^-2·d^-1. This study not only verifies the technical feasibility of efficiently immobilizing free cesium by a mild hydrothermal method, but also provides comprehensive spectroscopic experimental evidence and a kinetic prediction model for the long-term geological safety risk assessment of radioactive cesium solidified forms.

Research on the engineering prototype of the end fittings andspent cladding drying system

CUI Kai, WAN Zhenzhi, LI Wei, XIA Guozheng

RADIATION PROTECTION. 2026, 46(4): 313-323. doi:10.27045/j.1000-8187.202604004

Abstract ( 26 )

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To meet the conditioning requirements for highly radioactive solid waste, including end fittings and spent cladding generated during spent fuel assembly reprocessing, an engineering prototype of an efficient drying system for end fittings and spent cladding was developed. Based on an analysis of the heat and mass transfer mechanisms during the drying process and a comparison of common drying schemes, the process requirements and key functions of the drying system were identified. Following the process flow of “transfer → jacking and sealing → drying → detection,” the equipment modules and system layout were designed, and the engineering prototype was constructed. Tests on automatic compact drum transfer, waste drying, and remote disassembly and assembly of key components were carried out using the prototype. The key drying operating parameters were determined as follows: supply pressure of 0.2 MPa, supply flow rate of 130 Nm³/h, and initial supply temperature of 210 ℃; after 20 min, the supply temperature was adjusted to 190 ℃ for staged temperature control. The test results show that the system operates stably and reliably and meets the design requirements. A compact drum containing approximately 70 kg of end fittings and spent cladding with 3 kg of attached water can be dried within 60 min until the exhaust gas dew point is below -26 ℃. The results provide a basis for further optimization of the drying process. The developed drying system has good prospects for engineering application and can provide a technical reference for the design of similar spent fuel assembly reprocessing equipment.

Study on the conditioning of municipal sludge by synergistic process using microwave and electron beam irradiation

WANG Hao, WEI Chaomeng, GAO Chao

RADIATION PROTECTION. 2026, 46(4): 324-331. doi:10.27045/j.1000-8187.202604005

Abstract ( 25 )

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A novel synergistic conditioning process using microwave and electron beam irradiation was proposed to solve the problems of low dewatering efficiency and easy secondary pollution in traditional municipal sludge conditioning technologies. Municipal sludge with a moisture content of 87.04% from Sijiqing Sewage Treatment Plant in Huai’an City was used as the test material. Single-factor tests and orthogonal tests were carried out to investigate the effects of microwave power, microwave time, electron beam irradiation dose and irradiation sequence on sludge dewatering performance. The performance of different conditioning methods were compared by pressure filtration tests. The results show that electron beam irradiation dose and microwave time are significant factors affecting sludge dewatering performance (P<0.05). Under the optimal conditions of microwave followed by electron beam irradiation, microwave power of 200 W, microwave time of 30 s and electron beam irradiation dose of 9 kGy, the capillary suction time and specific resistance of the sludge are significantly decreased, and the moisture content of the filter cake is as low as 49.06%. This synergistic conditioning process does not require the addition of chemical reagents and generates no secondary pollution. It exhibits better dewatering performance than traditional chemical conditioning methods and can serve as a technical reference for the deep dewatering of municipal sludge.

Experimental study on the treatment of simulated supercriticalwater oxidation effluent by reverse osmosis

WU Shenao, SHANG Chaobo, YANG Shunlong, LI Chunhui, CHEN Yinqiang, JIAO Caishan

RADIATION PROTECTION. 2026, 46(4): 332-339. doi:10.27045/j.1000-8187.202604006

Abstract ( 23 )

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Reverse osmosis (RO) technology is one of the effective methods to address the inherent secondary waste volume issue in supercritical water oxidation (SCWO) treatment of radioactive organic liquid waste from nuclear power plants. To improve the metal ion rejection rate of the RO unit and further reduce waste generation, this study takes the simulated SCWO process effluent containing ions such as Li⁺, Cs⁺, Mn²⁺, Co²⁺ and Ni²⁺ as the research object, uses BW30 as the reverse osmosis membrane material, and investigates the effects of operating pressure, feed pH and feed flow rate on the metal ion rejection performance, membrane flux and volume reduction factor of the RO unit through orthogonal experiments, and analyzes the influence of residual acetic acid on the ion rejection rate. The results show that operating pressure is the dominant factor affecting the rejection of metal ions from the simulated wastewater by reverse osmosis. Under the operating conditions of feed pH 6, operating pressure 1.3 MPa and feed flow rate 1.4 L/min, excellent ion rejection and volume reduction performance can be achieved. The membrane has a rejection rate of over 98% for divalent metal ions, while the rejection effect for monovalent ions is relatively poor. Acetic acid has little effect on metal ion rejection, but its own rejection rate increases significantly with the rise of concentration. Scanning electron microscopy and atomic force microscopy characterization confirm that fouling phenomenon exists on the surface of the BW30 membrane, and attention should be paid to its long-term operation stability.

Corrosion of the reactor in the wet-oxidation of radioactive spent resin

XUE Hailong, YAN Xiaojun, GAO Zequan, WANG Zhiwei, GAO Chao, GUO Xiliang, YAN Wenfu

RADIATION PROTECTION. 2026, 46(4): 340-352. doi:10.27045/j.1000-8187.202604007

Abstract ( 30 )

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The treatment of radioactive spent resin by wet oxidation requires continuous processing of radioactive materials under strongly acidic and oxidizing conditions (dominated by hydroxyl radicals). The corrosion resistance of the reactor materials becomes a core concern in engineering applications. In this paper, the corrosion behaviors of three candidate reactor alloys, namely 316L, Incoloy 825, and Alloy 31, were systematically investigated under the wet oxidation conditions of spent resin. The corrosion degree, micromorphology, and characteristics of corrosion products of the alloys were characterized using the weight loss method combined with scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), and metallographic microscopy, and the corrosion mechanism was revealed. The results demonstrate that after 168 h of exposure, the uniform corrosion rates of 316L, Alloy 31, and Incoloy 825 were 0.022, 0.001, and 2.132 mm/a, respectively, demonstrating that the former two alloys possessed markedly superior corrosion resistance to Incoloy 825. Further enhancement of corrosion performance could be achieved by increasing the contents of chromium, molybdenum, and nitrogen in the alloy matrices. On the basis of the mandatory retirement criterion of wall thickness reduction by half, the estimated service life of Incoloy 825 was less than 2 years, whereas both Alloy 31 and 316L exceeded 40 years, thereby meeting the requirements for long-term safe service. This study provides technical support for the optimization and application expansion of materials used in wet oxidation technology for radioactive waste resins.

Study on the synthesis of a film-forming atomized fixative andradioactive aerosol control technology

CHEN Ran, CUI Chunsheng, WANG Chuangao, PANG Hongchao, LUO Zhiping, GUO Jinsen, LIN Yibo

RADIATION PROTECTION. 2026, 46(4): 353-360. doi:10.27045/j.1000-8187.202604008

Abstract ( 22 )

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To reduce the hazards of radioactive aerosols to personnel and the environment during the operation,maintenance and other activities of nuclear facilities, and to facilitate the recovery and treatment of radioactive aerosol particles, a film-forming atomized fixative was prepared via emulsion polymerization with butyl acrylate, methyl methacrylate and methacrylic acid as monomers. The fixative is used to capture and suppress radioactive aerosols, so as to mitigate the diffusion and resuspension of aerosols. Fundamental characterization and aerosol control experiments were performed. The results demonstrate that the fixative achieves a 2-hour capture efficiency of over 95% at a dosage of 300 mL/m³, with a resuspension rate of merely 0.2%. Field tests were further conducted in a reprocessing plant, showing that the control efficiency of fixative for radioactive aerosols in the first-level gas bladder reached 95% within 30 minutes during overhaul and maintenance. Accordingly, this film-forming atomized fixative exhibits excellent performance for radioactive aerosol control in nuclear facility maintenance, achieving efficient capture and significant inhibition of resuspension.

Pan Ziqiang’s birth

BAI Guang, ZHOU Mi, ZHANG Yanqi

RADIATION PROTECTION. 2026, 46(4): 361-365.

Abstract ( 14 )

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