Scarpitta Salvatore C, Miltenberger Robert P, Gaschott Robert, Carte Nina
Brookhaven National Laboratory, Upton, NY 11973, USA.
Health Phys. 2003 Apr;84(4):492-501. doi: 10.1097/00004032-200304000-00009.
A 5-inch-diameter Frisch Grid gas-proportional ionization chamber was utilized at Brookhaven National Laboratory (BNL) to rapidly characterize and quantify alpha-emitting actinides in unprocessed water, soil, air-filter, urine, and solid matrices. Instrument calibrations for the various matrices were performed by spiking representative samples with National Institute of Standards and Technology traceable isotopes of 230Th, 232U, 236Pu, and 243Am. Detection efficiencies were typically 15-20% for solid matrices (soil, concrete, filters, dry urine) and 45% for mass-less water samples. Instrument background over a 512-channel alpha-energy range of 3-8 MeV is very low at 0.01 cps. At optimum efficiency, minimum detectable levels of 0.56 mBq Kg(-1), 74 mBq L(-1) and 14.8 mBq filter(-1) were achievable for 40 x 10(-6) Kg soil, 1 x 10(-3) L tap water (or urine), and 4.5 cm diameter air-filter samples, respectively, each counted for 60 min. Data and spectra are presented showing the quality of results obtained using untreated samples obtained from the BNL Graphite Research Reactor Decommissioning Project. These samples contained Bq to MBq per gram amounts of (239,240)Pu, 241Am, and/or (234,235/238)U (as well as other beta/gamma emitters). Data and spectra are also presented for a very finely pulverized and homogeneous U.S. DOE/RESL soil reference standard (spiked with 239Pu, 241Am, and 233U) that was used to assess precision, accuracy, and reproducibility. Although this technique has its limitations, the advantages are (1) minimal sample preparation, (2) no separation chemistry required, (3) no chemical or hazardous waste generated, and (4) ability to immediately characterize and quantify alpha-emitting nuclides in most matrices. The benefits of this technique to the BNL/DOE Project Managers were rapid (1-2 d) turn-around times coupled with significant cost savings, as compared to commercial off-site analyses.
布鲁克海文国家实验室（BNL）使用了一个直径5英寸的弗里施网格气体正比电离室，来快速表征和量化未处理的水、土壤、空气过滤器、尿液及固体基质中的α发射锕系元素。通过向代表性样品中加入美国国家标准与技术研究院可溯源的230Th、232U、236Pu和243Am同位素，对各种基质进行仪器校准。固体基质（土壤、混凝土、过滤器、干尿液）的探测效率通常为15 - 20%，无质量水样的探测效率为45%。在3 - 8 MeV的512通道α能量范围内，仪器本底非常低，为0.01 cps。在最佳效率下，对于40×10(-6) Kg土壤、1×10(-3) L自来水（或尿液）和直径4.5 cm的空气过滤器样品，分别计数60分钟，最低可探测水平分别为0.56 mBq Kg(-1)、74 mBq L(-1)和14.8 mBq过滤器(-1)。给出了数据和能谱，展示了使用从BNL石墨研究反应堆退役项目获得的未处理样品所得到的结果质量。这些样品每克含有Bq到MBq数量的(239,240)Pu、241Am和/或(234,235/238)U（以及其他β/γ发射体）。还给出了用于评估精密度、准确度和重现性的非常细磨且均匀的美国能源部/RESL土壤参考标准（加入了239Pu、241Am和233U）的数据和能谱。尽管该技术有其局限性，但优点是：（1）样品制备最少；（2）无需分离化学；（3）不产生化学或有害废物；（4）能够立即表征和量化大多数基质中的α发射核素。与商业场外分析相比，该技术对BNL/DOE项目经理的好处是周转时间快（1 - 2天）且成本显著节省。
