RADIATION PROTECTION BULLETIN

Detection of Abnormal Radioactivity by Gamma Spectrum Block Counting Method in Environmental Monitoring

Niu Yunlong, Yang Weigeng, Wang Jiajun

RADIATION PROTECTION BULLETIN. 2020, 40(2): 1-5.

Abstract ( 53 )

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The block counting method is employed to explore whether a sodium iodide (NAI) detector can detect abnormal radioactivity is environmental monitoring, and to determine the specific value of early warning value. Four kinds of radioactive sources, ⁴⁰K, ¹³³Ba, ²⁴¹Am and ⁶⁰Co, were used for the experiment. The results show that it is feasible to use the method to detect abnormal radioactivity. The early warning value should be set to be greater than the mean value of background count plus 1-1.5 times the standard deviation of background count.

Experimental Study on Safety Effects of Redox Decontamination on Charging Pumps in Nuclear Power Plants

Cui Xiangqian, Zhang Xuefeng, Duan Congkai

RADIATION PROTECTION BULLETIN. 2020, 40(2): 6-11.

Abstract ( 63 )

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Taking martensitic stainless steel and austenitic stainless steel, the main materials of charging pumps in nuclear power plants, as study objects, we respectively tested the effects of solution concentration, reaction temperature and time on corrosion in the oxidation and reduction stages of a REDOX decontamination process. The corrosion of both materials in the whole process was then evaluated. A practical decontamination operation on a charging pump was also carried out in a nuclear power plant. With 0.25% potassium permanganate + 0.25% sodium hydroxide solution as the oxidant and 0.25% oxalic acid + 0.25% citric acid mixture as the reductant, under the effect of ultrasonic, we had them reacted at 70 ℃ for 4 h and 2 h respectively. It showes the steel sample surface is mainly of uniform corrosion, with an average corrosion amount of less than 1.5 g/m², which meets the requirements of relevant standards. At the same time, the radioactivity on the surface of the charging pump can be effectively removed. The formula and process can be applied to the decontamination of charging pumps in nuclear power plants.

Uncertainty Analysis of Environmental Cumulative Dose Measured by Thermoluminescence Method

Zhang Dechun, Gong Yudong, Li Le

RADIATION PROTECTION BULLETIN. 2020, 40(2): 12-16.

Abstract ( 78 )

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By analyzing the factors that may affect the measurement results in the process of environmental cumulative dose measurement by thermoluminescence (TLD) method, the uncertainty components of each link were evaluated. It shows that among the uncertainty components involved, the main considerations are class A caused by measurement repeatability, class B caused by scale factor, and Class A caused by TLD lofting process. In addition, the uncertainty caused by TLD slice screening and cosmic ray response is also large.

Monitoring of Radiation Environment around Urban Radioactive Waste Storage in Shanxi Province (2016-2019)

Wang Haiyong

RADIATION PROTECTION BULLETIN. 2020, 40(2): 17-21.

Abstract ( 73 )

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The urban radioactive waste storage in Shanxi Province is used to hold solid radioactive wastes and spent sources from nuclear technology utilization operations in the area. From 2016 to 2019, its stock of sources increased by nearly 1,000. The ambient radiation environment was monitored during the same period, with respect to gamma dose rate, alpha and beta surface contamination levels, total beta aerosol level, total alpha and beta levels in water, and gamma nuclide levels in soil. The results showed that the radiation level was within the natural background and no appreciable change was observed.

Comparison of Radioactive Surface Contamination Measurements in IAEA Global Laboratories

Dai Jiacheng, Chen Zhidong

RADIATION PROTECTION BULLETIN. 2020, 40(2): 22-26.

Abstract ( 74 )

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In order to improve radiation monitoring capabilities around the world, the International Atomic Energy Agency (IAEA) has organized a comparison project of laboratory radioactive surface contamination measurements. According to the requirements of IAEA, we developed a scheme with self-made three layer auxiliary brackets used. The measurement results obtained were evaluated as “ACCEPTABLE” in the IAEA comparison report. Based on the results of this comparison, several issues that should be paid attention to in the measurement of radioactive surface contamination are put forward.

Analysis of Abnormal Fluctuations of Radiation Monitoring Data in a Nuclear Power Plant

Li Jing, Chen Ligang

RADIATION PROTECTION BULLETIN. 2020, 40(2): 27-31.

Abstract ( 298 )

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The radiation and weather monitoring system (KRS system) of nuclear power plants is used to monitor whether there are abnormal changes of the environmental gamma dose rate in the plant and its surroundings. From the time and frequency of occurrence, and the trend of fluctuations, through analysis and experimental verification, we confirmed that dose rate data fluctuations of the AS4 sub-sites of the KRS system in a nuclear power plant are caused by radiographic inspection activities in 3MX and 4MX workshops.

Improvement and Application of Grading in Radiation Works of a PWR Nuclear Power Plant

Zhu Yuanli, Zhang Zhiqiang, Ma Laishan

RADIATION PROTECTION BULLETIN. 2020, 40(2): 32-34.

Abstract ( 87 )

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The improvement of radioactive work classification standards and its practical application in a PWR nuclear power plant is introduced. It is proved that the improved standards are reasonable, and effective for controlling the collective dose and other radiation risks.

Practice of Radioactive Solid Waste Minimization in a Nuclear Power Plant

Jiang Lei, Wang Zhao, Luo Jinsong

RADIATION PROTECTION BULLETIN. 2020, 40(2): 35-39.

Abstract ( 89 )

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The practical experience of radioactive solid waste minimization in a nuclear power plant is introduced, such as filter-element upgrade, online decontamination, sorted collection of waste, multi-filter-element support, and control of overhaul waste. By analyzing the volume of radioactive solid waste production over the years since its operation, the achievements of the nuclear power plant in waste minimization are confirmed.

Application of Gamma Spectrometry in Emergency Monitoring of Uranium-Containing Radioactive Wastewater

Liu Yuhang, Huang Ying, Du Yuanyuan, Gu Chuan, Chen Han

RADIATION PROTECTION BULLETIN. 2020, 40(2): 40-44.

Abstract ( 115 )

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Total alpha and gamma spectrum analysis were performed on a sample of uranium-containing radioactive wastewater, and the feasibility of measuring uranium-containing radioactive wastewater by gamma spectrometry was verified. It shows that, with this method, the efficiency can be effectively improved for the emergency monitoring of total radioactivity in uranium-containing radioactive wastewater. The selection of monitoring equipment suitable for the nuclides in the sample to be tested can effectively shorten the measurement time and improve the measurement accuracy.

Correction of Background Subtraction for TLD Personal Dose Monitoring in Nuclear Power Plants

Zhou Tienan, Wang Li, Jin Tian, Shi Xunwu, Xu Minghua, Gong Lei, Dai Shengqian

RADIATION PROTECTION BULLETIN. 2020, 40(2): 45-48.

Abstract ( 79 )

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The methods of background subtraction for thermoluminescence (TLD) personal dose monitoring commonly used in nuclear power plants are presented. TLD monitoring in NPPs has the characteristics of a large number of measurements, a large number of uses, and a long time-consuming measurement/annealing. The current subtraction method commonly used ignores the background differences caused by the scale of measurements and differet annealing times, which have a great impact on the accuracy of monitoring results. In response to the above problems, we attempt to use the cumulative time background to perform subtraction, for each dosimeter's reading and annealing time, to eliminate the dose error caused by these differences, so as to improve the accuracy of personal dose monitoring of occupational external exposure in nuclear power plants.

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