[en] Transmutation of highly active long-lived nuclides into shorter life nuclides is a promising option for the reduction of the nuclear waste radiotoxicity. Previous irradiation experiments which were carried out on ²⁴¹Am bearing spinel targets have shown a significant volume swelling that results from helium production. As a consequence, the helium release and trapping is considered as a key parameter for fuels and targets design. In this way, HELIOS irradiation experiment aims to increase knowledge between microstructure and in pile fuel behaviour for minor actinides transmutations in heterogeneous mode: 'once through'. For this program, five pins containing either Am based cercer or cermet (solid solution) were prepared. The Cea was responsible for fabricating the pin containing Am₂Zr₂O₇ pyrochlore in a MgO matrix which was chosen for its satisfying thermal property and irradiation behaviour. Research, development and fabrication steps carried out in Cadarache and Atalante facility to achieve the compound preparation are described in this paper. The first results on the obtained pyrochlore show that the materials exhibit the expected properties. (authors)

[en] The paper presents the optimal conditions for radiochemical separation of 241Am from environmental samples.

[en] The γ spectrum of ²⁴¹Am was reinvestigated using Ge(Li) detectors. 115 photons were found in this study, 46 of them for the first time

[en] Objective: To study the influence of crosstalk phenomenon on the measurement of gross radioactivity in drinking water. Methods: The gross activity in different standard materials with different thickness and area was measured using national standard method. Results: There was no obvious change in crosstalk factor with the increase of "2"4"1Am powder amount in the measurement, whereas the larger amount of uranium used might lead to larger crosstalk factor. The different measurement channels resulted in different crosstalk factors. The influence of beta radioactivity on alpha radioactivity measurement was significant. On the contrary, the alpha-to-beta crosstalk factor was negligible. The area of sample plate imposed no significant influence on crosstalk factor. Conclusions: The gross beta activity can be corrected to decrease the influence of alpha radioactivity using powder standard samples, when simultaneous alpha and beta counting mode is applied in measurement grass radioactivity in drinking water. (authors)

[en] Phase I consisted of the primary decontamination, packaging, and shipment of all ²⁴¹Am-contaminated gloveboxes, vent system, and miscellaneous waste items located in the laboratory restricted area in the J.C. Haynes house. The primary goals of Phase I were to locate and account for a major quantity of ²⁴¹Am which was unaccounted for and to remove all radioactive materials and contamination posing an imminent hazard to public health and safety. All Phase I operations were conducted under a Quality Assurance (QA) Program Plan and QA procedures written specifically for this program. In addition, certain generic Battelle QA procedures were used for routine tasks. All operations were conducted under strict health physics supervision and procedures. Cognizant ORAU and US Nuclear Regulatory Commission (NRC) personnel were on site during the entire Phase I operation and provided support and approval in the daily operations. All staff members had participated in previous decontamination and decommissioning programs involving transuranic waste and completed Phase I in a well controlled, timely, and safe manner

[en] In the EFTTRA-T4 experiment the irradiation behaviour of a target containing americium dispersed in MgAl₂O₄ was studied. Pellets containing 10-12 wt% ²⁴¹Am were fabricated by the infiltration method. However, it was found that the americium, intended to be present as AmO_2-x, formed a compound, probably AmAlO₃, during sintering. The T4 target was irradiated in the High Flux Reactor (HFR) Petten from August 1996 to January 1998 (358.4 fpd's). Post-test burn-up calculations indicated that the ²⁴¹Am concentration is reduced to 4% of the initial value at the end of the irradiation. The fraction of the initial americium atoms that were fissioned is 28%. Non-destructive and destructive examinations of the target indicated that swelling of the target pellets occurred. This is attributed to accumulation of helium, produced by alpha decay of ²⁴²Cm that occurs in the transmutation scheme of ²⁴¹Am

No abstract available

[en] Two gamma spectra in the 1MeV region, from ²⁴¹Am decay, were recorded, four gamma peaks supporting a 989.5keV, 9/2^-[505] ²³⁷Np level

No abstract available

[en] A submerged macrophyte of the Yenisei River, Elodea canadensis, was used to study the microdistribution of the artificial radionuclide ²⁴¹Am among different components of the plant. The total amount of ²⁴¹Am added to the experimental system was 1850 ± 31 Bq/L. The total amount of ²⁴¹Am accumulated by the plants was 182 Bq per sample, or 758,333 ± 385 Bq/kg dry mass. It has been found that the major portion of ²⁴¹Am accumulated by E. canadensis, up to 85%, was bound to solid components of the cells. It is observed that the microdistribution of ²⁴¹Am within different components of the submerged plant E. canadensis was not uniform. ²⁴¹Am distribution vary depending on the age of the leaf blades, the state of the cells and morphological features of the plant stem.