RADIATION PROTECTION

The on-site monitoring method of directional dose equivalent rate$\dot{H}$′(0.07) in the β-γ mixed field of nuclear facilities

WEI Yingjing, ZHANG Qiang, LI Houwen, TANG Zhihui, SHANG Jie, LIU Liye

RADIATION PROTECTION. 2019, 39(1): 1-6.

Abstract ( 134 )

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The field monitoring method of directional dose equivalent rate $\dot{H}$′(3) in β-γ mixed field in nuclear facilities is introduced. Based on the developed directional dose equivalent rate meter of ZF-D300 , its response characteristics to gamma rays and beta rays in γ standard radiation field, β standard radiation field and combined β-γ standard radiation field are given. Combined with the data of ambient dose equivalent rate meters, beta spectrometer and gamma spectrometer, the data processing method for measuring $\dot{H}$′(3) in β-γ mixed field is given. In the standard β-γ radiation field established in the laboratory, the difference of the $\dot{H}$′(3) values measured by the extrapolation ionization chamber of the standard instrument and this data processing method is less than 1%. During the outage of a nuclear power plant, the method of monitoring $\dot{H}$′(3) in the β-γ mixed field is applied.

Development of a directional dose equivalent rate monitorbased on thin plastic scintillation detector

WEI Yingjing, FANG Dengfu, SUN Xun, WANG Yong, CHEN Li, ZHANG Qingli

RADIATION PROTECTION. 2019, 39(1): 7-12.

Abstract ( 149 )

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Based on the thin plastic scintillation detector,MC simulation was used to optimize the probe combination structure of directional dose equivalent rate monitor. A directional dose equivalent rate instrument for monitoring weak penetration radiation was developed. In the range of 10 μSv/h to 100 mSv/h, the relative inherent error is less than ±6%. In the beta radiation field of ⁸⁵Kr, the angle response of -60° to 60° is better than that of ±40%. The average energy of beta radiation is in the range of 60 keV to 800 keV,and the energy response varies from -24% to 49%. The coefficient of variation is less than 2%. The experimental results show that the radiation performance of the directional dose equivalent rate instrument meets the requirements of GB/T 4835.1—2012.

Risk assessment of respiratory exposure from uraniummine dust after using masks

YE Yongjun, WU Wenhao, LI Zhi, YIN Ansong, DING Dexin

RADIATION PROTECTION. 2019, 39(1): 13-18.

Abstract ( 110 )

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A large number of long-lived α radioactive nuclides exist in uranium dust. Their contribution to uranium mine worker dose can not be ignored. The monitoring data of diameter and concentration of uranium dust particles after filtering with two commonly used masks were studied using the respiratory exposure risk evaluation model of uranium dust particles. The respiratory exposure dose and risk index were calculated for workers in a southern uranium mine. The results showed that: 1) Blind drift, stope and the main ventilation mashine room were the main places with more respiratory exposure dose than other places in uranium mine. 2) The respiratory exposure dose after using gauze mask and KN95 mask were 0.14-2.01 mSv/a and 0.03-0.53 mSv/a,respectively. The respiratory exposure dose and risk index for workers wearing KN95 masks was significantly lower than those wearing gauze mask. 3) When uranium grade was between 0.01% to 1% and uranium dust mass concentration was between 0.01 to 0.2 mg/m³,the workers’ respiratory exposure dose and risk index caused by the uranium ore dust particles were both increased with the increase of mass concentration of uranium dust.

Advantages and feasibility analysis of the use ofenriched boron in PWR nuclear power plants

FANG Lan, LIU Xinhua, XU Chunyan, FU Pengtao, LEI Qiang, GAN Xueying

RADIATION PROTECTION. 2019, 39(1): 19-26.

Abstract ( 380 )

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Natural boron is widely used for chemical compensation control of reactivity in PWR. Research shows enriched boron, as an alternative of natural boron, can optimize the primary loop hydrochemistry and therefore reduce the materials corrosion risk of primary loop structure and core deposition risk. It reduces the occupational exposure dose as well. This paper analyzes the advantages and feasibility of using enriched boron in PWR. It introduces the practical application of enriched boron in both domestic and overseas PWRs. Finally, suggestions are proposed on the application of enriched boron for HPR1000 and domestic operating PWRs.

Comparative study on the radon ventilation in hydropowerunderground engineering based on calculationof ventilation volume and radon exhalation rate

CHEN Gang, HU Penghua, LI Xianjie, REN Jianjun, KANG Jianqiao

RADIATION PROTECTION. 2019, 39(1): 27-32.

Abstract ( 131 )

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Taking a hydropower underground engineering project as an example, the air volume of radon reduction had been calculated according to the ventilation volume and radon emanation quantity. The result showed that the air flow could be reviewed according to the radon emanation quantity when the increment of underground radon concentration was greater than 200 Bq/(m³·h). Otherwise, the air flow could be reviewed on the basis of the ventilation volume. This method provided technical supports for the design of underground hydropower engineering.

Experimental study on dynamic mixing characteristics of thereaction type coating decontaminant

ZHANG Kun, HE Zeyin, TANG Weiyi, CAO Xingwei, HUANG Xiaming, LI Xiang

RADIATION PROTECTION. 2019, 39(1): 33-39.

Abstract ( 79 )

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Background: As one of the important techniques, coating decontamination technology can effectively deal with radioactive residues of nuclear accident. Decontaminating materials and its operating machines are important parts of coating decontamination technology. There are, however, some problems in the process of spraying decontaminating materials, such as the decontaminant inhomogeneouslly mixed and hard-to-peel the coating. Purpose: The well designed dynamic mixer can solve the issue of the decontaminant inhomogeneous-mixing. Methods: A new dynamic mixer is developed. The testing system of the dynamic hybrid characteristics of the decontaminating materials is set up to verify the rationality of the designed dynamic mixer. The tests of the mixing uniformity of the decontaminant, the film formation time, the stripping characteristics of the decontaminant, the microstructure and tensile strength of the coating are carried out. Results: The decontaminant material is evenly mixed. The mechanical property of the material film and the stripping characteristics meet the application requirements. Conclusions: The new designed dynamic mixer has good performance. The results of the study could provide important technical support for the improvement design of the decontamination vehicle.

Study on limit condition for operation in technical specifications ofthe radioactive specific activity in coolant of nuclear power plant

FU Yaru, PAN Nan, MEI Qiliang, LI Huaibin, MAO Lanfang

RADIATION PROTECTION. 2019, 39(1): 40-44.

Abstract ( 146 )

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The background and meaning of the limits formulation were revealed based on the study of the specific activity limits of primary coolant in Westinghouse standard specifications. This is helpful for the in-depth understanding and follow-up implementation of the relevant operation provisions. Through the comparison between AP1000 power plant specifications and Westinghouse standard specifications, it is found that the total specific radioactivity limit in AP1000 power plant specifications is replaced by the dose equivalent of ¹³³Xe specific activity limit in AP1000 power plant specifications. The dose equivalent of ¹³¹I and ¹³³Xe specific activity limit are calculated based on the design basis of 0.25% fuel cladding defect. The source terms used in shielding design, waste treatment system design and accident radioactive consequence analysis are consistent. Finally, combined with the requirements of domestic regulations and standards, some suggestions were given on adjusting the iodine spike specific activity limits and dose equivalent of ¹³¹I and ¹³³Xe specific activity limit according to the source terms of 0.25% fuel cladding defect.

Study on limiting condition for operation of the radioactivespecific activity of reactor coolant

WANG Lin, ZHANG Kuo, MAO Huan, XIONG Wenbin, FU Xiaohua

RADIATION PROTECTION. 2019, 39(1): 45-50.

Abstract ( 167 )

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Through the comparative analysis of the limiting condition for operation of the radioactive specific activity of reactor coolant in technical specifications of domestic and abroad, the study is focused on acceptance criteria of SGTR radiation accident consequences,and the main changes of different versions of national standard GB 6249. The measures to control CPR1000 NPP reactor coolant radioactive specific activity under different operation modes and potential application of the United States NPP technical specifications were discussed and suggestions were proposed.

Introduction to new environmental standard “Radiochemicalanalysis of plutonium in water and soil samples (HJ 814—2016)”

XIAO Jun, WANG Hongfeng, WANG Lili, CHEN Qianyuan

RADIATION PROTECTION. 2019, 39(1): 51-55.

Abstract ( 150 )

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The process of formulation and revision of the new environmental standard “Radiochemical analysis of plutonium in water and soil samples” is introduced in this paper. The implementation status and problems of the original related standards are analyzed. Main revisions of this standard are interpreted. The revised standard mainly includes the added application of tracer, the steps of sample pretreatment and analysis, requirements for blank experiment, and the instructions for the use of sample quantities and chemical yield indicators.

Study on the main changes of IAEA regulations for the safe transport ofradioactive material (2018 version) and its applicability to revise GB 11806

CAO Fangfang, PAN Yuting, HONG Zhe, ZHANG Liang, ZHANG Min

RADIATION PROTECTION. 2019, 39(1): 56-60.

Abstract ( 257 )

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GB 11806—2004 is technically equivalent to the IAEA Regulations for the Safe Transport of Radioactive Material (2003 Edition). Since then IAEA has revised the regulations several times, and the technical contents of the revised editions of 2012 and 2018 had changed a lot. Some of changes have major impact on the implementation of transport in related industries. This article briefly described the important changes of the latest version of the regulation (2018 version), and analyzed the changes and its applicability in order to revise and understand GB 11806 better.

Minimization practice and management of radioactivewastes in a uranium enrichment plant

XIAO Jianhua, ZHANG Xiaowen, YANG Rong, DU Renkai, ZHANG De

RADIATION PROTECTION. 2019, 39(1): 61-66.

Abstract ( 178 )

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The management status and minimization practice of radioactive wastes containing uranium in a uranium enrichment plant are introduced. Categorized collection, centralized disposal, and reduction of volume and amount of radioactive wastes are their basic requirements. Radioactive contaminated pipes and valves were cleaned with a mixed solution of 5% Na₂CO₃, 30% H₂O₂, and fresh water and reused in this plant to ensure that α surface contamination levels are less than 0.4 Bq/cm². By means of reutilization of rust removal solution and pressure test water and optimization of container cleaning process, the average amount of liquid waste produced by a single vessel was reduced by about 35%, these measures minimized the produced amount of liquid wastes containing uranium from origins. By changing the treatment process of small containers from wet process to dry process, the amount of produced waste water was reduced by 90%. The liquid waste produced from rust removal solution was also reduced by about 80% when it was reused for 5 times in a large container cleaning process. Increasing recycle ratio of adsorption tail liquid can reduce discharge amount of wastewater. Their wastewater treatment process was improved by adopting a calcium salt combined precipitation method. The average annual amount of dreg precipitate was reduced by 20%. The qualified rate of wastewater treatment was greatly improved. Some advices and measures are provided.

Study on the phenomenon of “stigmatization” ofnuclear projects and its countermeasures

ZHANG Zhenhua, ZHU Li, ZHANG Bo, CHEN Fangqiang

RADIATION PROTECTION. 2019, 39(1): 67-74.

Abstract ( 183 )

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Nuclear power is safe, clean and efficient. While social magnification of the risk of nuclear projects occurs due to the specialty and lack of knowledge about nuclear energy by public. The phenomenon of “stigmatization” is aggravated by the “not in my back yard”.After analysis of basic data of nuclear safety and radiation protection and comparison of risks between nuclear energy with others, suggestions are given, such as to expand the field and improve the forms of nuclear science popularization education at various levels, to establish a long-term nuclear science popularization education mechanism, to adjust the benefit distribution of nuclear projects reasonably and strengthen the capacity building of information dissemination platform.

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