Table of Content

20 May 2015 Volume 35 Issue 3

  

A study on framework of fission product source terms for PWR plants under normal operation

Liu Xinhua, Fang Lan, Zhu Zhaowen

RADIATION PROTECTION. 2015, 35(3):  129-135. 

Abstract ( 6 )   PDF (983KB) ( 0 )  

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The problems existing in the fission product source terms calculation for M310/CPR1000, EPR and AP1000 NPPs under normal operation are briefly analyzed. Based studies on the related regulations and standards, as well as operational feedback, review experiences and recent research achievements, a framework of fission product source terms estimation applicable for the PWRs in China was proposed. The proposed framework streamlines the calculation processes of fission product source term and has the requirements for deferent reactor types specified. The proposed framework can be taken as the foundation for solving the long-standing problems in the calculation of fission product source term and provide reference in source term calculation.

Study on the calibration of lung counter's efficiency and its effect from radionuclide's distribution

Xiao Yunshi, Liu Liye, Zhao Yuan, Wei Xiaofeng, Cao Qinjian, Xiong Wanchun

RADIATION PROTECTION. 2015, 35(3):  136-141. 

Abstract ( 8 )   PDF (1709KB) ( 0 )  

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Efficiency calibration is a key link in in vivo internal contamination monitoring of human body, and also is an important factor of the measurement accuracy. According to the CT images of the torso phantom, a three-dimensional voxel phantom is established. The Computational models of the HPGe detector is characterized by means of Monte Carlo transport codes, validated experimentally using point sources to verify the detector response at different energies and to further improve it with the inclusion of dead layers and inactive volumes on the crystals. A computer program is developed by Geant 4 to simulate the lung counter. By comparing on of the results of simulation and experimental results for lung counter detection efficiency of ²⁴¹Am, the differences are found as 2.47% (59.5 keV) and -8.58% (17.5 keV). Meanwhile a software was developed to solve the predicted values due to intake radionuclides by means of numerical solution of the ICRP biokinetics models. A case was studied on inhalation of class M ²⁴¹Am. It was analyzed how the other organs retentions influenced the efficiency calibration of lung counter. The results show that the whole body's efficiency is higher than the lung efficiency in the first two days and 50 days after intake ²⁴¹Am, and both efficiencies are more consistent in 3—50 days after intake ²⁴¹Am.

Analysis of public radiological risk after severe accidents for Xudapu NPP

Wang Mengxi, Zhao Bo, Liu Xinjian, Qiu Lin, Mao Yawei

RADIATION PROTECTION. 2015, 35(3):  142-145. 

Abstract ( 7 )   PDF (1074KB) ( 0 )  

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Acceptability criterion hasn't been made in China for assessment of public radiological risk incurred as a consequence of severe accidents. A methodology related to public radiological risk evaluation for NPP is presented in this paper. Besides, based on the site meteorological condition and population distribution, and the related Level 2 PSA reports, an accident consequence code system (MACCS) is used to calculate the exposure dose and risk after severe accidents for Xudapu NPP. Moreover, comparisons have been made with acceptability criterion in the USA and UK, which may serve as support for making acceptability criterion in China.

Performance study on sampling filters for sodium fluorescein method of HEPA filter field test

Chen Jianli, Wu Bo, Liang Fei, Zhang Jirong, Zhang Qun

RADIATION PROTECTION. 2015, 35(3):  146-151. 

Abstract ( 8 )   PDF (1324KB) ( 0 )  

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By the sampling requirement of sodium fluorescein method, a sampling filter performance-testing device was established using sodium fluorescein as aerosol agent. Seven glass fiber filter's resistance, background fluorescence and filtration efficiency of sampling flow rates from 0.92 to 2.75 m/s were measured, and then filter performance's influence on the purification factor was analyzed. Results show that the filtration efficiency of filter membrane has little effects on the purification factor of HEPA filter for the tested relative error of CF-A, FP5211 and GC90 are as low as 0.014%, 0.063% and 0.082% respectively. Mean while, effects of background fluorescence on system purification factor is obvious when the concentration of soaking solution is low; if the resistance were too large to limit collection of sodium fluorescein, it could increase interference of background fluorescence values. This study can provide guidance for evaluation, selection and usage of sampling filter.

Nitrogen-16 detection technology using background deducted LaBr₃:Ce scintillator

Shen Qiming, Zhang Jingbo, Liu Si, Tian Zhiheng

RADIATION PROTECTION. 2015, 35(3):  152-157. 

Abstract ( 10 )   PDF (1839KB) ( 0 )  

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Background count rate deducted LaBr₃:Ce scintillator was used to detect ¹⁶N. Results show a better detection efficiency and energy resolution of it, enabling full energy area detection thusly. An alert level of leakage was added that decreases the steam generator's threshold of leakage alarm. The function of count rate and energy spectrum integration is supplemented after alarming to display the real time leakage progress. Leakage simulation is achieved at different levels through slow and fast motion play of screen recording.

Experimental study on lowly concentrated CH₃I measurement for iodine absorber efficiency evaluation

Zhang Jirong, Li Yongguo, Wang Haiwei, Wang Tun, Han Lihong, Zhang Xueping, Zhang Qun, Zhou Sheng, Liu Xianli, Wu Bo

RADIATION PROTECTION. 2015, 35(3):  158-162. 

Abstract ( 5 )   PDF (931KB) ( 0 )  

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To overcome the defect of being radioactive operation, CH¹²⁷₃I was tentatively used in iodine absorber performance evaluation. The difficulty for the research is about the analytical method for CH¹²⁷₃I. This paper recommends that CH¹²⁷₃I is analyzed by GC. The results show that the limit deterministic concentration is low, the injected CH¹²⁷₃I is only 2% relative to the designed adsorbed capacity. The imported biggest amount of stable CH¹²⁷₃I will not greatly damage the performance of iodine absorbers to absorb radioactive CH¹³¹₃I in nuclear facilities. It is feasible when CH¹²⁷₃I is absorbed by chromatograph-grade ethanol, then analyzed by GC.

Water filter element used in radioactive water treatment systems of domestic Nuclear Power Plant

Kong Haixia, Shi Yingxia, Hou Jianrong, Hu Bo, Qiao Taifei, Chen Jianli, Li Yanzhang

RADIATION PROTECTION. 2015, 35(3):  163-169. 

Abstract ( 5 )   PDF (1028KB) ( 0 )  

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In the radioactive water treatment systems of Nuclear Power Plant, water filter elements are very important devices to ensure the plant stable operation, which are used to remove corrosion products in colloidal form in water and suspended solid particles. Through massive literature survey, this paper summarizes the specification size of water filter element, filtration rating, performance requirement, performance verification method, application information, and the development condition in the country. With the rapid development of the Nuclear Power Plant, the development and localization process of radioactive water filter element should be speeded up in China.

Experimental verification on statistical method of nuclear power plant effluent emissions in low level radionuclide

Zhang Yanxia, Li Jin, Li Hongyu, Han Shanbiao, Yuan Zhilun

RADIATION PROTECTION. 2015, 35(3):  170-175. 

Abstract ( 7 )   PDF (927KB) ( 0 )  

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As stipulated in China's national standard, measuring items lower than the detection limit in effluent radioactive emission statistics should be submitted to experimental analysis for reasonable estimation. To those truly unable to be estimated, use 1/2 of the detection limit value for emission statistics. Existing running NPPs abide by the standard all. Regarding the low-level radionuclide estimation, the state's nuclear and radiation relevant departments have organized NPPs for specific experimental studies to bring down detection limit. Experimental results show. When the detection limit is down to 1/20—1/2 of conventional limit, radionuclides not detected conventionally is still not detected; detection rate of a small amount of low level radionuclides detected in routine monitoring increases lightly. The detection values were slightly higher than the detection limit.

Discussion of radioactive iodine hazard estimation and protection caused by fuel defect for VVER unit

Li Zhonghua, Xie Jiangshan, Sun Kaibing, Wang Zhibing

RADIATION PROTECTION. 2015, 35(3):  176-179. 

Abstract ( 6 )   PDF (1282KB) ( 0 )  

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There is probability of fuel rods damage in PWR during operation. If the fuel rods damaged, the fission gases such as radioiodine will be released to the air of building, increasing the risk of internal exposure to personnel. According to the estimation of iodine hazard due to fuel rods damage for VVER unit, one damaged fuel rod can lead to air contamination of radioiodine as high as 84DAC. With reference to the practical NPP, radioiodine hazard control and protection measures such as the primary circuit purification, control of iodine releasing and diffusing to the air, air purification and personal protection are discussed, and some suggestions for similar situations are proposed.

Measurement of ²²²Rn and its decay daughters in uranium mines

Meng Dan, Xi Pingping, Ma Yinghao, Shen Fu, Fu Cuiming, Zhang Zhilong

RADIATION PROTECTION. 2015, 35(3):  180-187. 

Abstract ( 8 )   PDF (1456KB) ( 0 )  

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The paper stresses the importance of measuring radon decay daughters in radiation dose evaluations. The measurement methods including alpha spectrometry and gross alpha counting, are introduced and are used to measure the radon and its decay productions in a uranium mine then. The dose estimations and evaluations are performed based on the measurement data of radon and its daughters. It can be seen, though measurement data is limited, that the radiation doses from the radon decay productions should be paid due attention for the radon (particularly, its decay daughters) monitoring in uranium mines.

Methodology study on radon monitoring using activated charcoal canister under high humidity conditions

Mei Aihua, Liu Xiaosong, Qiu Shoukang

RADIATION PROTECTION. 2015, 35(3):  188-192. 

Abstract ( 5 )   PDF (1311KB) ( 0 )  

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To address the notable effects of humidity on radon measurement using activated charcoal canister, diffusion barrier and activated charcoal with high adsorption coefficient were adopted to develop an activiated charcoal canister sampleradapted for hight hunidity conditions. Under an ambient humidity of 95% and a sampling time of 2—5 days, the sensitivity and error of the radon measurements comply with the requirements of “Code for Indoor Environmental Pollution Control of Civil Building Engineering” (GB 50325). Providing with a sampling time of 72 h, the sampler's lower limit of radon detection is 10 Bq/m³.