The uptake and the long term behavior of Cs-137, Cs-134 and K-40 in the annual tree rings of spruce were examined. The youngest tree rings which are most active in water transport have higher activity concentrations, of K-40 and of radiocesium than the older ones. The activity concentration of Cs-137 in a water transporting tree ring can be well described as a function of the activity concentration of K-40. Furthermore a depth profile of the soil was taken and gives information, about the depth distribution of radiocesium and K-40.
In this work the transfer behavior of long living radionuclides from the Thorium decay series (Ra-228, Th-228, Th-232) as well as of K-40 and Cs-137 is studied. In a small area of middle Europe (southeast Gemany) showing an increased Thorium content of soil the activity concentrations in samples of feed plants, farm animals, farm animal products, roe deer has been determined. The concentration ratios feed-to-animal tissue and to animal products are calculated indicating a significantly enhanced transfer from feed to roe deer tissues. Determinations of the activity concentrations in fish (carp), pig (tissues), egg, milk complete this examinations. Among all studied samples which are important for human nourishing eggs and carp cause the greatest exposure by ingestion.
The uptake and the radial distribution of naturally occurring radionuclides in the tree rings of a spruce tree were examined. The activity concentrations of Pb-210 are at a constant level of about 1,7 Bq/kg dry weight (dw) in older tree rings but decrease to younger ones. We suggest that Rn-222 dissolved in the soil water is taken up in significant amounts by the tree roots and decays to Pb-210 within the wood. The activity concentrations of Ra-226 of about 2,0 Bq/kg (dw) are nearly constant over all tree rings. Ra-228 however showed a significantly different behavior. Futhermore the activity concentrations of U-, Th- and Pu-isotopes were determined. A depth profile of the soil within the root zone of the spruce gives further informations.
Authors:D. Jordan, R. Schupfner, and H. Schüttelkoff
A new method for the determination of Tc-99 in different environmental samples has been developed. The sample is carefully ashed in a muffle furnace and then fused with Na2CO3 and K2CO3. The first step is an enrichment and purification of TcO
on an anion exchange resin. The Tc is desorbed as a cationic thiourea complex, which is held on a cation exchange resin. The complex is destroyed by oxidation to TcO
with (NH4)2S2O8 in sulfuric acid. From this solution TcO
is extracted into TBP/toluene and the organic phase is mixed with a scintillation cocktail and counted in an anticoincidence shielded LSC. Tc-99m is used as a chemical yield tracer. The decontamination factors for all important fission and activation products and naturally occurring radionuclides are in the range between > 105 and > 108. The detection limit is about 5 mBq per sample at a counting time of 1000 minutes. The maximum sample amount of plants is 500 g dry weight and therefore the lowest detection limit achievable is 10 mBq/kg. Ashing and dissolution of the samples takes 24 h and 4 analyses are performed by one technician in 8 hours. The chemical yield ranges from 50 to 80%.
Authors:C. Scheuerer, R. Schupfner, and H. Schüttelkopf
This procedure to determine Ni-63 contributes to a safe and economically resonable decommissioning of nuclear power plants. Co-60, Fe-55 and Ni-63 are the most abundant long-lived radionuclides associated with contaminated piping, hardware and concrete for a period of several decades of years after shutdown, Samples are carefully ashed, leached, or dissolved by suitable mixtures of acids. The analysis starts with the absorption of Ni2+ on the chelating resin CHELEX 100. The next purification steps include an anionic exchange column and a precipitation as Ni-dimethyl-glyoxime, which is extracted into chloroform. After reextraction with sulfuric acid the solution containing Ni2+ is mixed with a scintillation cocktail and counted in an anticoincidence shielded LSC. The decontamination factors are determined for all important artificially and naturally occurring radionuclides ranging from above 104 to 109. The chemical yield adopts a value of (95±5)%. up to maximum sample amounts of 0,4 g steel, 5 g concrete and about 100 g of environmental samples the detection limits are about 5 mBq per sample or 12 mBq/g steel, 1 mBq/g concrete and 0,05 mBq/g environmental sample at a counting time of 1000 minutes.
Authors:W. König, R. Schupfner, and H. Schüttelkopf
This procedure for determining Fe-55 contributes to a safe and economically reasonable decommissioning of nuclear power plants. Co-60, Fe-55 and Ni-63 are the most abundant, long-lived radionuclides associated with contaminated piping, hardware, and concrete for several decades of years after shutdown. The analysis of Fe takes about three hours until the measurement with an anticoincidence shielded LSC Quantulus 1220 starts. The decontamination factors are ranging from greater than 105 to 109 for all important naturally and artificially occurring radionuclides except Sb. The chemical yield stays constant at a value of about 92% up to 0.1 g stable Fe in steel, concrete or other material. The detection limits (confidence level 95%) reach values of 8 mBq per sample or about 60 mBq/g steel and 1.5 mBq/g concrete at a counting time of 1000 minutes. Four to eight analyses are performed by one technician during eight hours.
Authors:R. Kandlbinder, V. Geißler, R. Schupfner, O. Wolfbeis, and B. Zinka
Bone tissues of thirteen deceased persons were analyzed to determine the activity concentration of the radionuclides 228Ra, 228Th, 232Th and 230Th. The activity ratios enable to assess the post-mortem-interval (PMI). The samples were prepared for analysis by incinerating
and pulverizing. 228Ra was directly detected by γ-spectrometry. 228Th, 230Th, 232Th were detected by α-spectrometry after radiochemical purification and electro-deposition. It is shown that the method is
principally suited to determine the PMI. A minimum of 300 g (wet weight) of human bone tissue is required for the analysis.
Counting times are in the range of one to two weeks.