Characterization of the NIST seaweed Standard Reference Material.

The National Institute of Standards and Technology (NIST) Standard Reference Material (SRM) for seaweed was developed through an interlaboratory comparison with 24 participants from 16 countries. After evaluating different techniques to calculate certified values for the radionuclides, the median method was found to be the most representative technique. The certified values were provided for 13 radionuclides and information values were given for 15 more radionuclides. Results for the natural decay series showed disequilibrium in both the uranium and thorium series.

Results of the European Commission MARINA II study: part I--general information and effects of discharges by the nuclear industry.

From the collated data relevant to discharges by the nuclear industry, it results that the input of beta activity (excluding Chernobyl fallout and tritium) into the OSPAR region decreased by a factor of 4 from 1986 to 1991, reaching by this date the same level as in the early 1950s. Over the same period the discharges of the alpha activity into the OSPAR region also decreased by a factor 3, the same trend has been seen also for tritium. Since 1986 the effective dose to members of the critical group in the vicinity of Sellafield and Cap de La Hague was consistently below the ICRP and EU limit of 1 mSv per year to members of the general public. The overall radiological impact from nuclear industry on the population of the European Union from the OSPAR area has decreased from 280 manSv y(-1) in 1978 to 14 manSv y(-1) in 2000.

Results of the European Commission Marina II study: part II--effects of discharges of naturally occurring radioactive material.

Enhanced levels of naturally occurring radioactive materials (NORM) are produced through various industrial operations and may lead to discharges to the marine environment. A recent study, called MARINA II, carried out for the European Commission considered discharges of radionuclides from the NORM industries to north European marine waters and their consequences. There are two main sources that were considered in the study. The use of phosphogypsum during the production of phosphoric acid by the fertiliser industry and the pumping of oil and gas from the continental shelf in the North Sea which produces large quantities of water contaminated with enhanced levels of naturally occurring radionuclides. Discharges of alpha emitting radionuclides from these two industries have contributed significantly to the total input of alpha emitters to north European waters over the period 1981-2000 (data were not available prior to 1981). Discharges due to the use of phosphogypsum have declined since the early 1990s and are now very low. Discharges from the oil and gas industries stabilised in the second half of the 1990s and are now the major contributor to alpha discharges to the region. As most European countries do not report discharges of radioactivity with the water produced during extraction, there is considerable uncertainty in the discharges used in the study. The impact of the discharges has been estimated both in terms of the effect on non-human biota and the radiological impact for people. In the 1980s the radiation dose rates to marine biota in the region around a phosphate plant on the north-west coast of England were as high due to the discharges from the phosphate plant as those near to the Sellafield reprocessing plant due to its discharges. In recent years the additional dose to marine biota in this region due to the past NORM discharges is of the same order of magnitude as the natural background. The collective dose rate was estimated to determine the radiological impact on people. The peak collective dose rate from the NORM industries occurred in 1984 and was just over 600 manSv y(-1). The collective dose rate fell with time as discharges from the phosphate industry reduced and was estimated as under 200 manSv y(-1) in 2000.

Sample cleanup by on-line chromatography for the determination of Am in sediments and soils by alpha-spectrometry.

A novel sample cleanup procedure for the Am determination in environmental samples by alpha-spectrometry is described. The method is based on the use of three analytical chromatographic columns. TEVA-Spec. from Eichrom has been packed in an analytical chromatographic column to carry out the lanthanide/actinide separation. A CS5A mixed-bed column from Dionex was used to separate Am from lanthanide impurities and other actinides. A TCC-II column from Dionex was used to connect the TEVA to the CS5A and act as a preconcentrator column for the trivalent ions. The behavior of the columns was studied by coupling the chromatograph to an ICPMS detector. A chromatographic fraction has been used for sample preparation for alpha-spectrometric determination of 241Am. The analytical procedure has been validated with certified reference materials (sediment and soil) and was applied to sediment core samples from the Irish Sea and compared with the classical radiochemical separation of Am.

Comparison between the use of direct current glow discharge mass spectrometry and inductively coupled plasma quadrupole mass spectrometry for the analysis of trace elements in nuclear samples.

The quantitative determination of trace elements in nuclear samples by GDMS and ICP-MS is presented and compared. Spectral interferences, matrix effects, detection limits, precision and accuracy are discussed. Results for selected samples demonstrated that both techniques are complementary. The use of a multi-standard solution provides the most accurate results in ICP-MS, whereas in GDMS this is achieved by relative sensitivity factors (RSF) matrix matched. Nevertheless, the use of standard RSF allows a fast screening.