RADIATION PROTECTION

Study on the migration of Pu in soil

Ni Youyi, Bu Wenting, Dong Wei, Guo Qiuju, Yang Bin, Quan Wei, Meng Ruijie

RADIATION PROTECTION. 2017, 37(1): 1-7.

Abstract ( 48 )

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The ultra-trace level of Pu (plutonium) isotopes in Chinese surface soil are mainly resulted from global fallout following the world-wide atmospheric nuclear tests last century. The vertical migration behaviors of Pu in soil were studied by field sampling and laboratory measurements using AMS (Accelerator Mass Spectrometry) and ICP-MS (Inductively Coupled Plasma Mass Spectrometry). Subsequently by fitting the vertical distribution of ^239+240Pu with the solution of convection-dispersion equation in single pulse condition, the apparent convection coefficient V in Chinese soils was found to be 0.046—0.163 cm/a, the apparent diffusion coefficient D ranged from 0.058 to 0.339 cm²/a and the migration velocity of ^239+240Pu concentration peak in soils of different areas from 0.063 to 0.187 cm/a. Based on these, the predicted ^239+240Pu concentration peak would remain in top 10 cm of the surface soil in Chongqing province after 200 years' migration. The results indicated that the organic matter content of soil would be a key factor influencing the migration behavior of Pu. Besides, other soil parameters such as porosity, soil particle size, cation exchange capacity etc. tend to have influences on the migration velocity of Pu in soils.

Discussion on doses to infant from intakes of radionuclides in public exposure

Yang Duanjie, Wang Yichuan, Fang Yuan, Chen Xiaoqiu

RADIATION PROTECTION. 2017, 37(1): 8-11.

Abstract ( 52 )

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Based on different dose coefficients and habit data for 3-month-old infant, 1-year-old infant and fetus/breast-fed infant, doses to these infant age groups from intakes of radionuclides in normal exposure situations are compared and analyzed. The results show that it is appropriate to use the dose coefficients and habit data of 1-year-old infant for evaluation of annual effective doses of <1-year-old infant age groups. Such dose calculation could represent potentially high doses of <1-year-old infant age groups.

Study of radiation field in beam injection region of BEPCⅡ

Yan Mingyang, Wu Qingbiao, Ding Yadong, Zhao Xiaoyan, Zhang Qingjiang, Li Nan, Ma Zhongjian

RADIATION PROTECTION. 2017, 37(1): 12-17.

Abstract ( 38 )

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When the beam is injected to the storage ring, the beam loss will influence the radiation field of beam injection zone and radiation protection zone. Using the beam loss monitoring (BLM) system to study the location and rate of beam loss, the results showed significant loss of beam in the injection zone and its downstream position. By the Monte Carlo simulation and experiment, the energy spectra of neutron and photon and their dose rates were obtained. When the beam is lost at the magnet,the peak of evaporation neutron spectrum is 0.9 MeV and direct emission neutron are not obvious. When the beam is lost at the vacuum tube,the peak of evaporation neutron and direct emission neutron are 4 MeV and 20 MeV, respectively. The energies of photons are mainly below 5 MeV. The dose rates of neutron and photon are at the same level. The dose rate during the injection is about two orders of magnitude higher than that without injection. The dose rate of photon in whole stage of electron positron collision experiment is about 1 000 μSv/h, which is an order of magnitude higher than neutron dose rate.

Comparative study on the application of CFD technology and SACTI model in local environmental impact simulation of natural ventilation cooling tower fog plume

Shi Xuefeng, Guo Dongpeng, Yao Rentai, Hu Jimin

RADIATION PROTECTION. 2017, 37(1): 18-26.

Abstract ( 37 )

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In this paper, the near flow field of cooling tower in a power plant in Shandong Province and the impact of fog plume lifting, drift droplets and salt deposits on local environment were simulated by applying CFD technology and SACTI model. The simulation results were consistent with the field experiment results. The SACTI model predicted that the maximum distance with drift droplets and salt deposits would occur in the range of 200 m near the cooling tower, whereas the CFD technology simulated that the maximum distance would occur around 500 m in the downwind direction. The maximum ground deposition of drift droplets and salt predicted by the SACTI model is about 3 times as much as by the CFD technology simulation, mainly because that the local circulation of cooling tower and the influence of surrounding buildings to drift deposition have been taken into account in the CFD simulation process.

Influence of inclined angle embedded pipe in shielding wall on radiation protection performance for electron irradiation accelerator

Zheng Fang, Chen Zhi, Xu Xie

RADIATION PROTECTION. 2017, 37(1): 27-33.

Abstract ( 34 )

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Some large diameter ducts through the shielding wall of the electronic irradiation equipment such as the radiation cable channel, will inevitably reduce the shielding capacity of the shielding wall. In this research, target photon spectrum of 3 MeV electron irradiation accelerator was divided into two segments: below and above 1 MeV. Distribution of radiation fields near the ducts' outlet were simulated at different inclination angles of pipes using the Monte Carlo code MCNP. As angle design is closely linked to shielding wall thickness, influence on the radiation field from two ranges of energy levels with different wall thickness were also compared. The results showed that scattered radiation field at the duct outlet was almost unchanged when photons of different energies passed through the shielding wall with the angles of the pipe no less than 45°. The fields of penetrating radiation outside the wall could be ignored for photons below 1 MeV. With the increase of inclination angles, the influence was significant for photons above 1 MeV. In addition, with the increase of wall thickness, lower energy photons were attenuated rapidly and the contribution from higher energy photons took the dominant role.

Effect of polypropylene fiber on performance of solidification matrix

Fu Yulong, Li Yuxiang, Li Jiping, Zheng Zhao

RADIATION PROTECTION. 2017, 37(1): 34-38.

Abstract ( 54 )

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Polypropylene fiber was added to the original recipe of cement solidification to avoid or reduce crack of radioactive spent resin matrix due to water-absorbing swelling. The test results showed that polypropylene fiber had a positive impact on inhibiting the growth of crack and improving the brittleness of the solidification matrix. The performances of strength,resistance to soaking, and resistance to freezing and thawing were also improved. A superior combination was obtained through an experiment in the following conditions: with w/c at 0.35, volume content of wet spent resins at 40%, and volume content of polypropylene fiber at 0.2%. Utilizing this formulation, the compressive strength of solidification matrix reached up to about 20 MPa, and its leaching rate and water resistance also satisfied related national standards.

A study on decontamination technology of ultrasonic wave cerium(Ⅳ)

Liu Yi, Chen Yan, Kong Yanrong, Li Ruizhi, Nie Peng, Zhou Yidong

RADIATION PROTECTION. 2017, 37(1): 39-44.

Abstract ( 38 )

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An ultrasonic wave cerium(Ⅳ) decontamination technology for stainless steel wastes produced in decommissioning process of nuclear facilities has been investigated. Using an orthogonal experiment method, the effects on corrosion weight loss rate and decontamination factor of stainless steel have been studied in different conditions, including concentrations of HNO₃ and Ce(NH₄)₂(NO₃)₆, temperature of solution, and ultrasonic time. Results showed that temperature and Ce(NH₄)₂(NO₃)₆ concentration would be the major influence factors. A maximum corrosion rate of 8.07 μm/h was obtained with the optimal parameters of Ce(NH₄)₂(NO₃)₆ (0.15 mol/L), HNO₃ (1.0 mol/L) and 85 ℃ for the decontamination process. The corrosion behavior of coupons was observed by a scanning electron microscope (SEM), and the results showed that cavitation corrosion was caused by ultrasonic wave occurred on the surface of a decontaminated coupon. A decontamination experiment for a section of spent fuels storage tube for demonstration was conducted, and a decontamination factor of 158.8 was achieved.

Test method study on aerosol diffusiophoresis in the containment

Chen Linlin, Sun Xueting, Wei Yansong, Shi Xiaolei, Xiao Zengguang, Ji Songtao

RADIATION PROTECTION. 2017, 37(1): 45-49.

Abstract ( 44 )

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Aerosol is the main carrier of radioactive fission products releasing from severe accident. Test method of aerosol migration mechanism affected by passive containment cooling system was established and carried out with a reference of the GRACE test in the European Joint Research Centre. The test results agree with both the GRACE results and theoretical calculations, thus confirming the reliability of the method.

Tritium concentration in carrot plant after short-term exposure to HTO vapor

Shen Huifang, Yao Rentai

RADIATION PROTECTION. 2017, 37(1): 50-55.

Abstract ( 39 )

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In order to study uptake and formation of tritiated water (HTO) and organically bound tritium (OBT) in carrots following acute exposure of airborne HTO, potted carrot plants were exposed to evaporated HTO for 1h in an exposure box at four different growth stages. The concentrations of tissue free water tritium (TFWT) and OBT in top and root were measured at the end of exposure and at harvest, respectively. The results showed that in most cases, it usually takes shorter than 1 h for the TFWT concentrations in the whole carrot top to reach equilibrium with the HTO concentration in the ambient air moisture. The TFWT concentration in the carrot top and root at harvest were lower than those at the end of exposure. In the carrot top, the relative TFWT concentrations at harvest represented about 1/389—1/86 of those obtained at the end of exposure; while these values were found to be about 1/116—1/3 in the root. In the carrot top and root, the exposure at the vigorous growth period generally ended with a higher OBT concentration at the end of exposure and at harvest. The OBT concentrations in the carrot top and root at harvest were lower than those at the end of exposure. When the exposure was conducted at the fleshy root expending stage, no obvious difference was observed for the OBT concentrations in the carrot top and root between at harvest and at the end of exposure. The concentration ratios of OBT to TFWT at harvest ranged from 2.79 to 20.73 in root, it is estimated that OBT would contribute much more to the ingestion dose than TFWT does.

Theoretical study on law of radon exhalation in radioactive water containing radon

Ye Yongjun, Dai Xintao, Ding Dexin, Jiang Juntin, Li Zhi

RADIATION PROTECTION. 2017, 37(1): 56-61.

Abstract ( 44 )

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One dimensional differential equation for radon migration in the water containing radon was established using radon seepage-diffusion migration theory and the formula for calculating the concentration of radon in water and the radon exhalation rate at the water surface were derived. In addition, the variation of radon concentration in water and radon exhalation rate at the surface of water were studied when parameter changes such as radon exhalation rate from the emanation medium at the bottom of water body, radon transfer rate, radon diffusion coefficient in water and the depth of the water. The results showed that:when the other parameters remain unchanged,(1)The concentration of radon at the same depth of water and radon exhalation rate on water surface increases with the increase of radon exhalation rate from the emanation medium at the bottom of water body;(2)The concentration of radon at the same depth of water decreases and radon exhalation rate on water surface increases with the increase of radon transfer rate; Furthermore, when radon transfer rate is larger than 1×10^-6m/s, the change of radon exhalation rate on water surface is not obvious with the change of radon transfer rate;(3)The concentration of radon at the same depth of water and radon exhalation rate on water surface increases with the increase of radon diffusion coefficient in water;(4)The concentration of radon in water that close to the surface and radon exhalation rate on water surface decreases with the increase of water depth.

Investigation and analysis of environmental radioactivity for a decommissioned uranium mine in Guangxi Province

Liao Yanqing, Lu Dexiong, Peng Chong, Xu Mingfa, Ju Zhiping

RADIATION PROTECTION. 2017, 37(1): 62-66.

Abstract ( 56 )

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The impact of environmental radiation on a decommissioned uranium mine in Guangxi Province was conducted with a series of relevant analyses. The results showed that the levels of gamma absorbed dose rate, radon exhalation rate, and natural radionuclide concentrations in soil and surface water were lower than the national decommissioning management limits, suggesting the effectiveness of the decommissioning treatment.

Environmental survey and evaluation of natural radioactivity in Baotou City

Zhang Baosheng, Lv Wanting

RADIATION PROTECTION. 2017, 37(1): 67-72.

Abstract ( 57 )

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This environmental survey for natural radioactivity in Baotou City was conducted with measurement of γ absorbed dose rates in air and with measurement of ²²²Rn, ²²⁰Rn and their progenies concentrations. The average value of γ instantaneous dose rates measured in Baotou city was 62.5 nGy/h. The mean cumulative dose rate of γ ray in air was 100.7 nGy/h, which was consistent with both the γ instantaneous dose rate after subtraction of the cumulative dose rate of cosmic rays and the aerial survey value (60 nGy/h) of Baotou City in 2006. The α potential energy concentrations of the ²²²Rn and ²²⁰Rn progenies in aerosol were 12.88 and 9.55 nJ/m³, respectively, and both of them were within the range of standard limits. The annual effective dose in Baotou City was estimated to be 0.58 mSv from external exposure and 1.29 mSv from internal exposure, which are slightly higher than the national average value and the world-wide average. The effective dose from natural radioactivity in Baotou City did not exceed the regulatory limits, and thus, would not pose a threat to public health.

Analysis and dose assessment of ⁸⁵Kr released from NPP

Huang Yanjun, Guo Guiyin, Zhang Bin, Tao Yunliang, Sha Xiangdong, Chen Chaofeng, Shangguan Zhihong

RADIATION PROTECTION. 2017, 37(1): 73-79.

Abstract ( 25 )

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In this paper, the characteristics and environmental behavior of ⁸⁵Kr released from NPP are presented. The analytical methods for ⁸⁵Kr in gaseous effluents from NPP and in environmental samples (including air and water) are also investigated and summarized. Our research indicated that the most effective analytical method for ⁸⁵Kr in effluents and in low-level air and water is Liquid Scintillation Spectrometer (LSC) with a series of separation and purification procedures. Meanwhile, the atmospheric dispersion factors of ⁸⁵Kr were studied using typical release source terms for the CPR1000, AP1000, and Hualong One reactor types. The results indicated that the exposure dose to the public would be extremely small.

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