Objective To develop the method of analyzing α-radionuclides using large area grid ionization chamber.Methods Ultrasonic dispersion and vacuum drying system was used to prepare sample source,large standard thin source and plutonium plane source were used to optimize the working condition of spectrometer,and calibrate the instrument for analyzing α emitters.The certified reference materials (GBW04127) were used to verify the accuracy of the method.Results The non-linearity of calibration curve for standard thin sources of neptunium,plutonium and americium was less than 0.2％,and the resolution were 112,84 and 106 keV,respectively.The counting efficiency was 31.2％ for the large standard thin source.The values of specific activity measured in this way were in good agreement with those of the certified reference materials.232Th,238U,230Th,234U/226Ra,210Po,222Rn and 218Po were analyzed in a uranium mineral sample,and their specific radioactivity values were 5.3,3.8,35.6,21.4,27.0,19.6 and 11.1 Bq/g,respectively.Conclusions The method can be used to analyze α spectrum quickly in low-level radioactive environmental samples.

Objective To establish a method of analyzing total uranium and 235U/238U ratio in urine using inductively coupled plasma mass spectrometry (ICP-MS) and uncertainty assessment.Methods Urine sample was digested with HNO3 and H2O2,and total uranium was determined using ICP-MS method directly.The digested urine sample was separated to concentrate uranium with tributyl phosphate (TBP) column,and 235U/238U ratio was analyzed using ICP-MS.The uncertainty was evaluated through sample pre-treatment,measurement and standard curve calculation.Results The recovery of total uranium in urine was 98.4％-102.4％,detection limit was 0.002 μg/L.The relative expanded uncertainty of total uranium concentration in urine was 0.26 (k =2).235 U/238 U ratio was 0.001 1 (k =2).Conclusions This study offers a low detection limit,good recovery and precision method for rapid determination of total uranium and 235U/238 U ratio in urine samples.It is potential used for both in occupational exposure assessment and nuclear emergency situation.The uncertainty evaluation of total uranium and 235U/238U ratio in urine are reliable.

Objective To summarize the analytical results of radioactivity in the food and drinking water nationwide following the Fukushima nuclear accident,and to evaluate its possible contamination to the public health in China.Methods According to the national standard methods and IAEA,FDA correlative references,the scheme was established on sampling and measurements in food and drinking water after the breakout of the accident.The quality control was requested on the sampling,analyses and data report.Results Trace artificial radioactive isotope of 131I was measured in spinach samples on 2 April 2011 in Beijing. Subsequently 131I was found in 10 kinds of growing leaves vegetables (open field)nationwide.The maximum detectable activity of 131I in vegetables was about 3.1 Bq/kg.Since 3 May 2011,the concentration of 131I has been below the detection limits.No artificial radionulide was detectable in all of milk,drinking water and marine products samples during March to December,2011.Conclusions The food and drinking water measurements in China following the Fukushima nuclear accident denoted that the minor amounts of 131I in vegetables might result in very low absorbed dose and induce no impact on human health.The maximum detectable activity of 131I in vegetables was close to that reported in European countries,and much less than that measured in China immediately after the Chernobyl accident in 1986.

Objective To develop a rapid and reliable method for determination of 210Po using large-area grid ionization chamber α spectrometry.Methods Samples were digested using a microwave digestion system.After preparation of sample source,the concentration of 210Po in clam was detected by large-area grid ionization chamber (φ 25 cm).209Po tracer was used to obtain the recovery.Results Large-area grid ionization chamber could achieve better counting and α spectrum resolution when the optimized thickness was 250 μg/cm2.By spiking 209Po tracer in clam,the minimum detectable activity was 9.870 × 10 4 Bq and the recovery of 210Po was 98％.Conclusions Compared with the traditional method,the developed method can avoid separation process,using less quantity of sample (0.2-0.5 g dry) and simplify the measurement process.This method may be has broad application prospects.

Objective To investigate the activity concentration of 90St in tea produced in Chinese typical regions,enrich the baseline data for 90Sr level in Chinese tea,and evaluate possible exposure doses to people.Methods Samples were carbonized,ashed,digested and leached,and then extraction chromatography method was used to separate 90Sr and 90y.After preparation of sample source,radioactivity of 90Y was measured using low-level α/β counter.Results Twenty six kinds of tea produced in 16 typical regions from 26 cities of 16 provinces were collected in 2016,and their 90Sr activity concentrations were analyzed using the separation method of di (2-ethylhexyl) phosphate (HDEHP) extraction chromatography.The results revealed that the activity concentrations in 26 kinds of tea samples ranged from 0.28 to 3.78 Bq/kg,and contributed possible exposure doses of 0.44 × 10-2-6.00 × 10-2 μSv to each people.Conclusions These doses were far less than the ICRP annual dose limit of 1 mSv for the public,suggesting less impact on people's health.

Objective To ascertain the concentrations of uranium in drinking water around nuclear power plants.Methods A total of 106 water samples were collected from June 2009 to March 2010 in Jiangsu,Zhejiang,Liaoning and Shandong provinces.Inductively coupled plasma-msgs spectrometry(ICPMS)was applied to determine uranium content in local water source and drinking water.The detection limit of U was 0.8 ng/L.The recovery was 100.9%.Results The uranium concentrations in all samples were less than 15μg/L which was the limit given by World Health Organization(WHO).Conclusions The concentration of uranium in water sources was as follows:Liaoning>Shandong>Jiangsu>Zhejiang.The concentration of uranium in drinking water W88 maximal in Shandong Province and minimal in Zhejiang Province.

Objective To establish an effective and reliable method for analysis of uhratrace uranium in multi-stage atmospheric particles providing the monitoring and evaluation of the content of radioactive uranium in the atmosphere.Methods A large volume six-stage-impactor sampler of atmosphere particles was used to collect aerosol samples,and uhratrace uranium in particles was digested using microwave and measured by inductively coupled plasma mass spectrometry.The filter material,digestion conditions and microwave digestion system had been optimized.Results The background of uranium level on the cellulose filter was the lowest,and the samples were digested by using HNO3-HCI (aqua regia)-H2O2 solution.Reference material SRM2783 was used to validate the accuracy of the method,and the relative error of the 238U was 7％,The detection limit of the method was 2 × 10-4ng/m3.The aerosol actual samples were analyzed using the established method.The mass concentrations of uranium in PM2.5 was in the range of 0.023-0.065 ng/m3.Conclusions The established method was effective and reliable to monitor the concentration level of ultratrace uranium in multi-stage atmospheric particles.

Objective To ascertain the uranium isotopic ratios in surface water samples around nuclear power plants.Methods Water samples were collected in Jiangsu,Shandong and Zhejiang provinces.An efficient separation procedure for the trace uranium concentrated from surface water by tributyl phosphate (TBP) was used.Inductively coupled plasma mass spectrometry (ICP-MS) was applied to determination of low abundance uranium isotopes.Results The 234 U/238 U isotope ratio varied from 4.575 × 10-5to 7.752 × 10-5 and 235U/238U from 7.273 × 10-3 to 7.639 × 10-3.Conclusions The 234U is enriched in the surface water.

Objective To ascertain the uranium concentrations and uranium isotopic ratios in drinking water in Xilingol League,the Inner Mongolia Autonomous Region.Methods Drinking water samples were collected in Xilingol League,the Inner Mongolia Autonomous.Region inductively coupled plasma mass spectrometry (ICP-MS) was applied to determine the concentration of uranium and uranium isotope abundance.Results The uranium concentrations in all samples were in the range of 2.73-18.9μg/L,with an average of 8.20 μg/L.Tbe234U/238U isotope ratio varied from 7.513 × 10-5to 3.003 × 10-4 and235U/238U from 7.196 × 10-3 to 7.391 × 10-3.The relative standard deviation (RSD) was less than 0.5％ for234U/238U and 0.2％ for235 U/238U.Conclusions The uranium concentration in samples collected from Dongwuqi was high than 15 μg/L,whih is the limit given by World Health Organization (WHO).The uranium in drinking water originates from the natural environment.The234U is enriched in drinking water.

Objective To establish a porcine model of penetrating-suture pancreaticojejunostomy.Methods Ten domestic pigs were selected,and after general anesthesia they underwent laparotomy and the pancreas was visualized.Then the pancreas was dissected at the level of superior mesenteric vascular,and the proximal pancreatic stump was sewed up.The anastomosis between the distal pancreatic stump and the intestinal wall adopted penetrating-suture pancreaticojejunostomy; the digestive tract was reconstructed by Roux-en-Y.Results The anastomosis with penetrating-suture pancreaticojejunostomy was successful in ten domestic pigs.The mean pancreatic stump diameter was 2.5 cm,and the mean pancreatic duct diameter was 1.5 mm,the mean time for operation was 1.0 ～ 2.5 h,and the average time of pancreaticojejunostomy was 8 minutes.The mean blood loss was 25 ml.After operation,diarrhea occurred in 2 pigs and wound infection occurred in 1 pig,and all were cured with appropriate management.No pig died intra-operatively,and no pancreatic fistula or death occurred after operation.Conclusions A porcine model of penetrating-suture pancreaticojejunostomy is successfully established.