IAEA-385

A sample of about 250 kg of sediment was collected from the Irish Sea (54.3°N, 3.7°W) by the Centre for Environment, Fisheries and Aquaculture Science (CEFAS), Lowestoft, U.K., in 1995. The sediment, which was sent to IAEA-MEL for processing, was frozen for 2 hours at -40°C, and then freeze-dried with a +5°C/h temperature increase rate. Secondary drying was performed over 24 hours under 0.02 mbar pressure at a constant temperature of +40°C. The sediment was then ground into powder, sieved through a 250 µm mesh and homogenized by mixing in a nitrogen atmosphere. The samples were bottled in polyethylene flasks under nitrogen gas, sealed with polyethylene caps and labeled with the code IAEA-385. The bottles containing 100 g of sediment powder each were sterilized according to ISO standards at 25 kGy in an irradiation facility.

Reference date for decay correction: 2019-01-01

Certified values for massic activities (based on dry mass)

*The uncertainty is expressed as an expanded uncertainty using a coverage factor k = 2 estimated in accordance with
the JCGM 100:2008 'Evaluation of measurement data - Guide to the expression of uncertainty in measurement' [1] and
ISO Guide 35 [2].
¤Radium-226 values should be corrected for ingrowth from Th-230.
#Radium-228 values should be corrected for ingrowth from Th-232.
•Americium-241 values should be corrected for ingrowth from Pu-241.

The values listed above were established on the basis of statistically valid results submitted by laboratories which had participated in an international interlaboratory comparison organized by the IAEA Marine Environment Laboratories, Monaco. The details concerning the criteria for qualification as a certified or information value may be found in the report IAEA/AL/151 (attached).