IAEA-384 , Fangataufa Sediment

Inorganic , Sediments

A sample of about 158 kg of sediment was collected by IAEA-MEL in July 1996 in Fangataufa Lagoon (French Polynesia), where nuclear weapon testing had been carried out. The sediment was frozen for 2 hours at -40°C, then freeze-dried with a +5°C increase in temperature per hour. Secondary drying was done over 24 hours under a pressure of 0.02 mbar at a constant temperature of +40°C. The sediment was then ground into powder, sieved at 250 µm and homogenized under nitrogen gas. The samples were then bottled in flasks under nitrogen gas, sealed with polyethylene caps and labelled with the code IAEA-384. 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: 1996-08-01

Certified values for massic activities
Radionuclide Certified value [Bq kg-1] 95% Confidence interval [Bq kg-1]
40K 6.8 6.5-7.1
60Co 2.50 2.40-2.60
155Eu 7.0 6.7–7.3
230Th 2.50 2.38–2.61
238U 35.5 33.4–36.8
238Pu 39.0 38.6–39.6
239+240Pu 107 103-110
241Am# 7.1 6.7–7.4

# The values should be corrected for in-growth from 241Pu

Information values for massic activities
Radionuclide Information value [Bq kg-1] 95% Confidence interval [Bq kg-1]
90Sr 1.7 1.5–1.9
137Cs 0.30 0.24–0.50
210Pb(210Po)$ 22 21-23
226Ra 2.4 2.0-2.9
228Ra 1.6 0.8–2.0
232Th 0.022 0.008–0.024
234U 40 35-43
235U 1.70 1.60–1.96
239Pu 98 85-105
240Pu 17.5 15.1–18.7
241Pu 55 41-69

$ 210Pb and 210Po are considered to be in equilibrium

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/126 (attached).


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