Demand driven salt clean-up in a molten salt fast reactor - Defining a priority list

The PUREX technology based on aqueous processes is currently the leading reprocessing technology in nuclear energy systems. It seems to be the most developed and established process for light water reactor fuel and the use of solid fuel. However, demand driven development of the nuclear system opens the way to liquid fuelled reactors, and disruptive technology development through the application of an integrated fuel cycle with a direct link to reactor operation. The possibilities of this new concept for innovative reprocessing technology development are analysed, the boundary conditions are discussed, and the economic as well as the neutron physical optimization parameters of the process are elucidated. Reactor physical knowledge of the influence of different elements on the neutron economy of the reactor is required. Using an innovative study approach, an element priority list for the salt clean-up is developed, which indicates that separation of Neodymium and Caesium is desirable, as they contribute almost 50% to the loss of criticality. Separating Zirconium and Samarium in addition from the fuel salt would remove nearly 80% of the loss of criticality due to fission products. The theoretical study is followed by a qualitative discussion of the different, demand driven optimization strategies which could satisfy the conflicting interests of sustainable reactor operation, efficient chemical processing for the salt clean-up, and the related economic as well as chemical engineering consequences. A new, innovative approach of balancing the throughput through salt processing based on a low number of separation process steps is developed. Next steps for the development of an economically viable salt clean-up process are identified.

Simulation of thermal fluid dynamics in parabolic trough receiver tubes with direct steam generation using the computer code ATHLET

In the present feasibility study the system code ATHLET, which originates from nuclear engineering, is applied to a parabolic trough test facility. A model of the DISS (DIrect Solar Steam) test facility at Plataforma Solar de Almería in Spain is assembled and the results of the simulations are compared to measured data and the simulation results of the Modelica library “DissDyn”. A profound comparison between ATHLET Mod 3.0 Cycle A and the “DissDyn” library reveals the capabilities of these codes. The calculated mass and energy balance in the ATHLET simulations are in good agreement with the results of the measurements and confirm the applicability for thermodynamic simulations of DSG processes in principle. Supplementary, the capabilities of the 6-equation model with transient momentum balances in ATHLET are used to study the slip between liquid and gas phases and to investigate pressure wave oscillations after a sudden valve closure.

An analytical solution for the consideration of the effect of adjacent fuel assemblies; extension to VVER-440 type fuel assemblies

A new analytical method is described to deal with the Leakage Environmental Effect for the cross section production. The method is based on the one dimensional analytical solution of the two-group diffusion equation for two adjacent, homogenized fuel assemblies. The high quality of the results for this highly efficient method is demonstrated for square fuel assemblies. In additional tests the limiting case for the transferability of the concept to the small hexagonal VVER-440 type fuel assemblies is shown.

Development of the coupled 3D neutron kinetics/thermal-hydraulics code DYN3D-HTR for the simulation of transients in block-type HTGR

The Light Water Reactor (LWR) dynamics code DYN3D is extended and adopted for the application to block-type High Temperature Gas-Cooled Reactor (HTGR). A procedure for the cross section generation for the HTGR core calculations was developed. The modified Reactivity-Equivalent Physical Transformation (RPT) approach is applied in order to eliminate the double-heterogeneity of HTGR fuel elements in the deterministic lattice calculations. A full core analysis of the reference simplified HTGR core is performed with DYN3D using macroscopic nodal cross sections provided by HELIOS.

The SP3 transport approximation is integrated into the multi-group DYN3D code to take anisotropy of the neutron flux and heterogeneity of the core more precisely into account. The SP3 method was developed for hexagonal geometry of the graphite blocks, where the hexagons are subdivided into triangular nodes.

A 3D heat conduction module coupled with a channel-type coolant flow model is implemented into the code. It is shown that there is significant redistribution of the produced heat by heat conduction between the graphite blocks.

[Special care units for the treatment of acutely ill, cognitively impaired geriatric patients in Germany]

During recent years, specialized wards have been established in geriatric hospital departments as a consequence of the growing need of special care for acutely ill older patients, who are also cognitively impaired. However, there are neither established standards nor any commonly agreed concept of care. A written survey among 12 specialized wards in Germany revealed some characteristics of these wards: extended geriatric assessment, special education of staff including validation and gerontopsychiatric issues, and particular equipment/architecture, such as hidden doors and group rooms, and in some cases loop tracks for walking, therapeutic facilities, and 'living rooms' on the wards. There is a wide variability with respect to the designation of these wards, the number of beds, length of stay, and admission criteria. It appears from this survey that there should be an exchange of empirical experience made on these wards, and there is a need of collaborative research on its usefulness.

Identification of novel polymorphisms in intron 7 of the human p53 gene in acute myeloid leukemia and healthy donors

Screening for mutations by PCR-SSCP in exons 5 to 9 of the p53 gene in 38 bone marrow or peripheral blood specimens of patients with acute myeloid leukemia (AML) showed abnormal shifts in 9 cases. One reflected a mutation in exon 8, whereas in the other cases there were no exonic mutations identified by sequencing. As PCR primers were chosen annealing in the introns flanking the exon region, following sequencing of the encompassing introns identified 5 base substitutions at various sites in intron 7. Two of them have been described previously [1] and 3 novel polymorphisms could be identified. To determine whether these polymorphisms are linked to the pathogenesis of AML, we screened peripheral blood specimens of 26 healthy controls. We found identical base substitutions in 6 out of 26 controls. Our data suggest that these polymorphisms are not related to the pathogenesis of AML.

Cyclosporin A inhibits cytokine-induced proliferation in B-chronic lymphocytic leukemia

We investigated the effects of the immunosuppressant cyclosporin A (CsA) on proliferation of neoplastic B-cells from patients with B-chronic lymphocytic leukemia (B-CLL). Cell growth was induced in vitro by tumor necrosis factor alpha (TNF-alpha (8/16), interleukin 2 (IL-2 (9/16) or both (7/16), in 4 cases spontaneous proliferation was observed. We were able to demonstrate that CsA inhibits cytokine-induced proliferation, as measured by [3H]-thymidine incorporation, in all cases responsive to TNF-alpha or IL-2 as well as in spontaneous proliferation. CsA did not increase the fraction of trypan blue positive cells or apoptosis. Growth inhibition by CsA occurred in a dose dependent manner: 100 ng/ml CsA was the optimal concentration which blocked about 90% of cytokine induced or spontaneous proliferation. We could also demonstrate that the effect of CsA was reversible and that no blocking effect was observed when CsA was added later than 48 hours after stimulation. Cell cycle analysis using propidium iodide as a DNA stain demonstrated that CsA prohibited the progression of B-CLL cells from the G1-phase to the S-phase of the cell cycle. However, we were also able to show that TNF-alpha induced proliferation of hairy cell leukemia (HCL) was not affected by CsA. This observation indicates that the inhibitory activity of CsA seems to be restricted to only a few haematological diseases such as B-CLL.