[Objective] To monitor the content of radionuclides in food in a area of Beijing,investigate the impact of nuclear facility on the environment and human health,and provide a basis for the improvement of sample preparation and measurement methods in food radioactivity monitoring.[Methods] 19 samples covering vegetables,meat,grain,fish,milk and tea were collected from the regions around 30 km of nuclear facility and the control regions.After vacuum freeze drying,the samples were installed into Marinelli backers.The radionuclides in samples were measured by BE 6530 type high purity germanium gamma spectrometer with low background.The analysis and evaluation were based on the Gamma spectrometry method of analyzing radionuclides in biological samples (GB/T 16145-1995) and the Limited concentrations of radioactive materials in foods (GB 14882-94).[Results] 134Cs,60Co,58Co and 238U were not detected in all samples.137Cs was detected in 8 samples with a range of (0.015-0.580) Bq/kg(or L milk).232Th 和 226Ra were detected in some samples with ranges of (0.047-4.400) Bq/kg and (0.085-2500) Bq/kg,respectively.40K was detected in all samples with a range of (45-657) Bq/kg (or L milk).The contents of 137Cs,232Th and 226Ra did not exceed the standard limits.[Conclusion] The nuclear facility did not cause radioactivity pollution on the environment of this area in 2016,and the detected samples will not cause harm to health in daily consumption.The method of Marinelli backers filled with powder samples by vacuum freeze drying can meet the requirements of monitoring,and it is suitable for environmental radioactivity level investigation.

Objective To study the activity concentration background of the radioactive noble gas 133 Xe in the atmosphere in Beijing,and to provide fundamental data for scientific assessment of air quality and effective reply of unexpected atmosphere radioactive contamination in Beijing.Methods A total of 117 noble gas xenon samples of Beijing were collected during the period from July to October,2016,and the activity concentrations of 133Xe were analyzed and measured with the Canberra BE3825 HPGe γspectrometer system.Results The activity concentrations of 133 Xe were detected in 9 out of 117 samples with the range of 0.25 ～ 5.01 mBq/m3,while no radioactive xenon 133Xe were detectable in the other samples.Conclusion The 133 Xe activity concentration background in the atmosphere of Beijing can be used as reference of radioactive contamination of air,and should be monitored constantly.

[目的]针对2011年3月11日日本福岛核事故,于2011—2013年采取相应的技术措施监测北京地区河、湖水与饮用水放射性污染水平,即该两类水中总α、总β放射性水平,确保饮用水的放射性污染水平不超过国家相关标准限值要求,为将来河、湖水的放射性水平可能发生的变化提供基础数据。[方法]制定采集计划,每年分别在枯水期和丰水期采集河、湖水和饮用水,样品的采集覆盖北京市16个区（县）,依据GB/T 5750.13—2006《生活饮用水标准检验方法》和GB 5749—2006《生活饮用水卫生标准》进行采集,采用相对比较测量法对水样总α、总β放射性进行测量分析。[结果]河、湖水样品中,总α放射性水平算术平均值范围为0.06~0.15 Bq/L,总β放射性水平平均值范围为0.20~0.25 Bq/L;饮用水样品中,总α放射性水平算术平均值范围为0.09~0.11 Bq/L,总β放射性水平平均值范围为0.08~0.10 Bq/L。[结论]2011—2013年北京地区河、湖水及饮用水在枯水期和丰水期的放射性水平均未超过国家生活饮用水卫生标准指导值。

目的 了解北京地区大气中放射性惰性气体氙(131Xem、133Xe、133Xem和135Xe)的活度浓度,加强该地区放射性污染监测.方法 采集2013年1月1日-8月16日期间北京地区大气中的176个惰性气体氙样品,使用高纯锗γ谱仪测量样品中131Xem、133Xe、133Xem和135Xe的活度浓度.结果 在所检气体样品中,1个样品检测出131Xem的活度浓度为8.82 mBq/m3,6个样品检测出133Xe的活度浓度为0.27-0.36 mBq/m3,其余样品中均未检出131Xem、133Xe、133Xem和135e.结论 监测期间,该地区大气中未发现存在明显的放射性污染,但131Xem和133Xe作为反映大气放射性污染状况的关键核素,应对其进行持续监测.

This paper reports the brief process and results of radioxenon monitoring and analysis in Beijing following the Fukushima Daiichi nuclear power plant accident. The accident and release of volatile radionuclides were caused by 9.0 magnitude earthquake and tsunami on March 11, 2011. The maximum concentrations of 133Xe and 131mXe were in excess of 0.90 Bq.m−3 and 0.047 Bq.m−3, respectively. The activity ratio of 131mXe to 133Xe and the dynamic trend of 133Xe activity concentration were analyzed.

Objective To understand the radiation hazard factor and its level in radiopharmaceutical production sites by cyclotron,so as to provide guidance for radiation protection.Methods A cyclotron typed HM-20S and its workplace,which belonged to a hospital,were studied as the object.The classification of radiation hazard factors and grade of the workplace were confirmed according to the relative national regulations and technological standards.The related protection facilities and measures were analyzed and assessed at the same time.Results The project of radiation protection was formulated for commissioning of the radiopharmaceutical producing workplace,and the entrance compartment to hot area was devised in GMP(Good Manufacturing Practice) plan.The radiation level of outside controlled areas and focus points in the workplace were calculated.The maximum was 9.6μSv/h on the manipulation location while 222GBq of 18F was operated in the work box with 60mm Pb.The source of activated products was discovered and some protection suggestions were claimed.The concentration level of O3 in the accelerator room was much lower than the occupational limit,which restricted in the criterion,while the cyclotron with self-shielding was running.Conclusion The protection measures for both radioactive contamination and external radiation were taken into considerations sufficiently in protection designing of the radiopharmaceutical producing workplace.However,the shielding of cyclotron room and protective door also should be optimized in the project of radiation protection.

The radioactive contamination in Beijing caused by the Japanese Fukushima nuclear accident was monitored. In this research, samples of air, rainwater, surface water and vegetables in Beijing were collected and measured to estimate the radioactive contamination levels in Beijing. During the period from the 15th to the 41st day after the first emission of radioactive material (first emission) from the Japanese Fukushima nuclear power station (NPS) on 12 March 2011, obvious radioactive contamination was found in the Beijing air samples. The maximum concentration of I-131 was 5.89 mBq m(-3) in the air samples detected on the 22nd day after the first emission, and the maximum concentration of Cs-137 and Cs-134 was found on the 20th day after the first emission. Except for one sample of rainwater, no artificial radionuclides associated with Fukushima were found in surface water. The measurement results showed that there was no harm to the health of local Beijing residents.

Objective To detect radionuclide contents in soil in Beijing following the Fukushima nuclear accident,and to evaluate the levels of radioactive contamination.Methods The system of nuclear emergency monitoring was activated.High purity germanium(HPGe)γ spectrometer was used to analyse specific activities of radionuclide 226Ra,232Th,40K and 137Cs in all 28 soil samples.Results The artificial radionuclide 131I was not detected in all the samples.The artificial radionuclide 137Cs was tested in 24 samples and the highest value was 6.01 Bq/kg(the sample collected at No.200 outside the yard in Changping District).The mean specific activities of radionuclide 226Ra,232Th,40K and 137Cs were 16.76,27.12,451.12 and 1.24 Bq/kg respectively,which were lower than the levels in Beijing measured in the 1980's.Conclusion The minor amounts of 137Cs in soil mostly came from the previous nuclear event and induced no visible impact on human health.

[Objective]To analyze the results of radioactivity in the vegetables and the original milk following the Fukushima nuclear accident,and evaluate the levels of radioactive contamination in the food in Beijing Region.[Methods]The system of nuclear emergency monitoring was run,then the radioactive contamination level of vegetables and original milk of Beijing were tested by using the HPGe γ spectrometer system.[Results]Trace artificial radioactive isotope of 131I was detected in shepherd's purse samples on April 2,2011 in Tongzhou District of Beijing.The maximum detectable activity isotope of 131I in vegetables(open field) was about 3.03 Bq/kg during the period from April 2 to June 30,2011,and no artificial radionuclide was detectable in all the samples of original milk during the period.[Conclusion]The minor amounts of 131I in vegetables released from the Fukushima nuclear accident results in very low absorbed dose and induce no visible impact on human health.The maximum detectable activity of 131I in vegetables is much less than that measured in Beijing after the Chernobyl accident in 1986.

The process of aerosol sampling and measuring of Beijing Radionuclide Station and Beijing Radionuclide Laboratory of the Comprehensive Nuclear-Test-Ban Treaty(CTBT) International Monitoring System(IMS) was described.Long time aerosol monitoring data of the station and the laboratory were analyzed through statistic method and the characteristic and rule of the concentration distribution of nuclides 7Be,137Cs and 131I were obtained.The foundation was formed for further studying the rule of the radionuclide distribution in atmosphere.

Objective To determine the radiation dose level outside of a helical tomotherapy room and formulate a reasonable protection designing project of the radiation treatment room, and to ensure that the project is worked out to provide radiation safety protection safeguard for the clinical application of TOMO facility.Methods A helical tomotherapy facility typed Tomotherapy Hi-Art of a hospital was studied as the object researched. According to performance parameters of the facility, relative technical standards such as NCRP report No.151, GBZ/T 201.2-2011 and QC rules of the AAPM Task Group No.148, the shielding and safety protection design of the tomotherapy room were confirmed. The protective effect of the room was appraised. Results The shielding design project was determined as follows: the eastern, western protective wall and ceiling of the tomotherapy room should be constructed with barites of 95 cm thickness of barites, southern wall with 70 cm barites, inner wall and external wall of the maze should be constructed with 70-30 cm and 30-70 cm of barites respectively. In addition, a protective door with 8mmPb shielding should be set at the entrance of the room. All the radiation dose levels penetrating from the room wall were calculated, and it was shown that the maximum radiation dose rate in the facility interlayer alleyway outside wall was 8.89 μGy/h, and the cable channel under ground ( 3.25 μGy/h) ranked the second. The maximum value outside of the protective door reached 1.6 μGy/h. Based on the above data, the highest annual effective dose received by the radiation workers in the treatment place was 0.27 mSv, and the relative public near the treatment room was not more than 0.03 mSv/a. Conclusion Leakage radiation should be primarily taken into consideration during radiation design for a helical tomotherapy room. Meanwhile, the relevant control protection effect of the treatment room also should be assessed in terms of the real irradiation parameters, the workload and room conditions.

Objective To assess the radiation protection and safety of Intra-operative radiotherapy(IORT) with a mobile accelerator, and to provide guidance of radiation safety for clinical application of IORT. Methods A Mobetron mobile accelerator and its working room of a hospital were determined as the research object. After the workloads of IORT and annual dose goals were confirmed, the radiation level surrounding the IORT room and the doses received by the personnel were calculated When the irradiation condition was set in the worst scenarios, In addition, the radiation shielding of IORT room were checked. Results Under the radiation protection of the IORT room being designed as the same shielding structure as the room of an ordinary X-ray diagnostic device, the dose rates were calculated as follows: 35-78 μSv/h outside east wall, 89 μSv/h outside south wall, 70-84 μSv/h outside west wall and 75-106 μSv/h outside north wall. The maximum rate of the general treatment room below the IORT room was 64 μSv/h and the dose rate of the space above the treatment room was 45 μSv/h. At the same time, it was shown that all the annual doses calculated from 5 h of cumulative beam-on time met the requirement of dose goal for the highest annual dose received by occupational radiation staff were 0.53 mSv, and the annual doses of public were lower than 0.1 mSv. The radiation safety settings including some corresponding safety facilities, available protection apparatus and effective management measures were employed to prevent operators from entering or staying in IORT room incorrectly.Conclusion The dose management goal of IORT with a mobile accelerator operated in an ordinary operating room could be achieved with infinitesimal radiotherapy workload, but the IORT spot should be fixed and the treatment room should be added with relevant shielding materials in terms of actual workload and controlling requirement of dose rate.

讨论了实验室检测中经常遇到的怎样给出生活用品中"不含放射性"的结论的难题,介绍了检测工作的科学性、严谨性,放射性核素衰变的种类及特性,放射性的通用物理探测方法,推荐了一套使用通用物理探测仪器逐步排除样品的放射性污染,以及如何给出生活用品中"没有放射性"的结论。

Objective To enhance the protective management and to design a feasible shielding project by measuring the real radiation level of Intra-operative radiotherapy (IORT) with a mobile accelerator (accelerator) in / outside the operating room. Methods A Mobetron mobile accelerator and the operating room were selected as the research object. Under the condition of simulating IORT with 1000cGy / min of 12MeV electron beam,the radiation level both from the IORT operating room and from its peripheral place were obtained by the test tools including LiF(Mg,Cu,P) thermoluminescent dosimeters(TLDs) ,an environmental dose rate meter typed 6150-AD. Results (1 ) The radiation level and dose distribution in the IORT operating room. In the Z = 75 plane(couch plane) ,an exposure value of approximately 40. 8 ～ 62. 8mGy / h at 100cm in the front of the unit and a value of approximately 0. 13 ～ 11. 2mGy / h at 100cm at the back of the accelerator were measured,while a value of approximately 2. 05 ～ 6. 35mGy / h at 300cm in the front of the device and at the lateral of the unit. (2) The radiation safety setting of the IORT operating room and the radiation level outside the room. The IORT operating room and its preparing rooms were regarded as controlled area and all doors of the site were interlocked with beam on. Under the circumstance of the above radiation state set,there were maximum of 9. 0μGy / h in the aisle (which is separated by the preparing rooms) outside east wall and 19. 5μGy / h in the controlling room outside north wall of the operating room. At the same time,24. 2,14. 5 and 23. 0μGy / h were shown as the maximum value from clean hall outside west wall,the place outside south wall and under the floor correspondingly. Conclusion The radiation resulted from IORT accelerator operation was belong to mixed scatter radiation of bremsstrahlung in the operating room. It is desirable that an IORT operating room should be located at an appropriate immovable place and the shielding design plan should be determined and optimized on the basis of practical radiation level.

目的提出大气放射性气溶胶连续监测大流量空气采样中所遇问题(如滤膜堵塞、滤膜吸水及空气中颗粒物对探测效率的影响)的解决办法。方法通过对连续监测取得的数据进行分析,通过实验模拟滤膜堵塞情况,并通过实际工作验证。结果获得具有连续代表性的样品,并且获取到有效监测结果数据的天数占全年天数的比例逐年上升,2003～2006年分别为71%,86%,94%,96%。结论通过采取综合手段,能够减小不利气候因素对采样连续代表性的影响,获得理想的数据有效率。应通过对探测效率进行修正而减小空气中颗粒物含量对探测效率的影响。

It describes the situation of continuous monitoring of radioactive aerosol in atmosphere in Beijing using large volume air sampler,describes calculation of Minimum Detectable Activity(MDA) and Minimum Detectable Concentration(MDC) of radionuclide in continuous monitoring of aerosol in Atmosphere,and analyzes MDAs and MDCs of several typical man made radionuclide.

为掌握北京市2001-2008年放射性职业人员受外照射个人剂量监测的基本状况,以制定有效的个人剂量监测方案,巩固和促进本地区个人剂量监测工作的发展,使用LiF(Mg,Cu,P)热释光剂量计(TLD)定期监测,建立本市Access个人剂量数据库并使用TLPs软件进行处理分析,依据国家有关法律法规和技术标准进行评价.监测结果表明,本市绝大多数放射性职业人员的个人剂量水平较低,相应的辐射工作环境是安全的.提示,在放射防护实践中应加强重点工种人员的个人剂量监测与防护,同时应强化相关法规的落实和人员培训.

In order to test the γ shielding effect of PET special working-boxes to 18F,the conversion formula using calculate formula of γ point-source absorbed dose rate and substitute 137Cs for 18F is deduced.Only the absorbed dose rate of 137Cs sealed source is measured at the reference point,the absorbed dose rate of 18F can also be calculated at the same preference point according to the convetsion formula.The shielding effect of PET special working-boxes to 18F can be evaluated by means of these calculated data.These calculate data using this conversion formula is basically accordant with the measured data at site.

Abstrcat This paper describes the work that Beijing Municipal Center for Disease Prevention and Control participate the intercomparison of measurement for radio nuclides in construction materials organized by Chinese Center for Disease Control and Prevention. The construction material samples were measured by High Pure Germinium γ spectrometer. Results reported by our laboratory agree well with the reference values from Institute of Radiation Protection and Nuclear Safety, Chinese Center for Disease Control and Provention. This work verified our laboratory' ability for measuring radio nuclides in construction materials.