A new certified reference material (CRM) for radionuclides in sea water from the Irish sea (IAEA-443) is described and the results of the certification process are presented. Ten radionuclides (3H, 40K, 90Sr, 137Cs, 234U, 235U, 238U, 238Pu, 239+240Pu and 241Am) have been certified, and information values on massic activities with 95% confidence intervals are given for four radionuclides (230Th, 232Th, 239Pu and 240Pu). Results for less frequently reported radionuclides (99Tc, 228Th, 237Np and 241Pu) are also reported. The CRM can be used for quality assurance/quality control of the analysis of radionuclides in water samples, for the development and validation of analytical methods and for training purposes. The material is available in 5 L units from IAEA (http://nucleus.iaea.org/rpst/index.htm).

A comparison of the coincidence summing correction methods is presented. Since there are several ways for computing these corrections, each method has advantages and drawbacks that could be compared. This part of the comparison was restricted to point sources. The same experimental spectra, decay scheme and photon emission intensities were used by all the participants. The results were expressed as coincidence summing correction factors for several energies of 152Eu and 134Cs, and three source-to-detector distances. They are presented and discussed.

The long-time series of 7Be activity in surface air have been studied with the wavelet analysis technique in order to find coherence between 7Be activity, theoretical production in the troposphere and climatic indices. The 7Be activity were obtained from five different locations, Angra in the tropics in Brazil, Skåne in mid-latitudes in Southern Sweden, Kiruna in Polar region in Northern Sweden, Loviisa in Southern Finland and Rovaniemi in polar region in Northern Finland. The 7Be data from the Northern hemisphere sites where tested for coherence with theoretical production of the isotope in troposphere and with the North Atlantic Oscillation index. In the Southern hemisphere separate theoretical production was calculated in order to describe local production and Southern Annular Mode was used as the climatic index. Consistent and significant coherence were found with theoretical production at Skåne, Kiruna and Loviisa at time-scales of four years or longer. At Angra and Rovaniemi sites, no coherence was detected between 7Be theoretical tropospheric production and measured activity at ground level. The coherence between 7Be data from Skåne and Angra and climatic indices is insignificant while data from Northern and Eastern Scandinavia show clear coherence with climatic indices at time-scales of four years or longer. Additionally, significant coherence was found between the cosmic ray induced production and NAO at the time band of 8–12 years whereas the coherence between cosmic ray induced production and SAM was insignificant. This feature implies that the ground level 7Be activity contain mixed information on both production and transport. This conclusion means that further evaluation through models which enable accurate realistic models that will be investigated in future studies.

An intercomparison of the methodology (alpha, beta and gamma spectrometry) used for 238U, 235U and 210Pb determination was carried out based on 38 sediment samples. The activity range of the samples varied from 10–700 Bq/kg for 210Pb, 1–35 Bq/kg for 235U and 10–800 Bq/kg for 238U. Results obtained using the three methods were not statistically different at high activity levels, but agreement between the results decreased at lower sample activity levels. For 210Pb, the smallest difference was found between alpha and gamma spectrometry. A good correlation between results from alpha and gamma spectrometry was observed over the whole activity range. In beta spectrometry, the results were slightly higher than those obtained by alpha or gamma spectrometry due to the impurity of 228Ra. In 238U analysis, good correspondence was observed between 238U determined by gamma and alpha spectrometry, particularly at higher 238U activity concentrations over 100 Bq/kg. In 235U analysis, attention needs to be paid to interference from 226Ra and its reduction.

Natural radioactivity due to the presence of 226Ra, 232Th and 40K in selected building materials (cement, sand, bricks, gypsum and ceramic) used in Egypt was measured using a gamma-ray spectrometer with an HPGe detector. The average activity concentrations observed in different building materials ranged from 10.0 +/- 1.3 to 109 +/- 6, <2 to 55.8 +/- 2.2 and 5.5 +/- 1.7 to 684 +/- 34 Bq kg(-1) for 226Ra, 232Th and 40K, respectively. Based on these, together with previously reported results, the effective doses received by the residents of different types of house within all Egyptian governorates were assessed using the WinMat computer program. The results were below 1 mSv a(-1) in all cases. The collective effective dose indoors was assessed as 15,000 man Sv and the excess effective dose due to building materials was 0.07 mSv a(-1).

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 13radionuclides and information values were given for 15 more radionuclides. Results for the natural decay series showed disequilibrium in both the uranium and thorium series.