[en] This work presents the implementation of the Adjoint Sensitivity Analysis Procedure (ASAP) for the non-equilibrium, non-homogeneous two-fluid model, including boron concentration and non-condensable gases, of the RELAP5/MOD3.2 code. The end-product of this implementation is the Adjoint Sensitivity Model (ASM-REL/TF), which is derived for both the differential and discretized equations underlying the two-fluid model with non-condensable(s). The consistency requirements between these two representations are also highlighted. The validation of the ASM-REL/TF has been carried out by using sample problems involving: (i) liquid-phase only, (ii) gas-phase only, and (iii) two-phase mixture (of water and steam). Thus the 'Two-Loops with Pumps' sample problem supplied with RELAP5/MOD3.2 has been used to verify the accuracy and stability of the numerical solution of the ASM-REL/TF when only the liquid-phase is present. Furthermore, the 'Edwards Pipe' sample problem, also supplied with RELAP5/MOD3.2, has been used to verify the accuracy and stability of the numerical solution of the ASM-REL/TF when both (i.e., liquid and gas) phases are present. In addition, the accuracy and stability of the numerical solution of the ASM-REL/TF have been verified when only the gas-phase is present by using modified 'Two-Loops with Pumps' and the 'Edwards Pipe' sample problems in which the liquid and two-phase fluids, respectively, were replaced by pure steam. The results obtained for these sample problems depict typical sensitivities of junction velocities and volume-averaged pressures to perturbations in initial conditions, and indicate that the numerical solution of the ASM-REL/TF is as robust, stable, and accurate as the original RELAP5/MOD3.2 calculations. In addition, the solution of the ASM-REL/TF has been used to calculate sample sensitivities of volume-averaged pressures to variations in the pump head. (orig.)

[en] Research on the structure of short life-time isomeric states of ¹¹²In and their interaction with extranuclear fields is presented. Isomeric states have been populated in reactions ¹¹²Cd(p,n), ¹⁰⁹Ag(α,n) and ¹¹²Cd(d,2n) using the pulsated beam method. The results of the studies performed can be summarized as it follows: I. Nuclear structure. In the case of ¹¹²In, there are two isomeric states having Jsup(π)=8^-(Tsub(1/2)=2.81.μs) and Jsup(π)=6⁺(Tsub(1/2)=0.69.μs) and excitation energies of 606,0 KeV. The desintegration procedure schematically represented of the new isomeric states is: 8^-(262.7 KeV - M2) 6⁺(187.8 KeV - E2)4⁺. The magnetic momenta of the isomeric states are: π(8^-)-3.03+-0.03 m.n. μ(6⁺)-4.05+-0.04 m.n. The quadripolar electric momentum of the 8^- isomeric state is: [Q(8^-)] = 0.093 +- 0.006 b. The 8^- isomeric state stands for the minimum energy level of the multiplet generated by the [π(lgsub(9/2))ν(1hsub(11/2))] configuration. The 6⁺ isomeric state was described by a mixture of configurations resulting from coupling the lgsub(9/2) proton state with the 2dsub(5/2), 2dsub(3/2) and lgsub(7/2) neutron states. II. Population sections. In studying the relations of isomeric sections into double even isotopes sup(110-116)In, excited in (p,n) reactions, a very high population of the 8^- isomeric states is pointed out, on condition that the positive parity isomeric states were satisfactorily described in the statistical model. The anomaly observed in the population of states 8^- can be explained by the influence of the selection rule after γ upon transitions γ, which confirm the existence of the multiplet of levels generated by the [π(lgsub(9/2))ν(1hsub(11/2))] pure configuration in these nuclei. III. Examination of effects induced by irradiation defects in the InAg system. The short life-time isomeric states of ¹¹²In, excited in reaction ¹⁰⁹(α,n), were used in the study of hyperfine interactions by means of the method of angular distributions disturbed in an external magnetic field. (author)

[en] This work presents the implementation of the Adjoint Sensitivity Analysis Procedure for the nonequilibrium, nonhomogeneous two-fluid model, including boron concentration and noncondensable gases, of the RELAP5/MOD3.2 code. The end product of this implementation is the Adjoint Sensitivity Model (ASM-REL/TF), which is derived for both the differential and discretized equations underlying the two-fluid model. The consistency requirements between these two representations are also highlighted

[en] This work presents results that illustrate the validation of the Adjoint Sensitivity Model (ASM-REL/TF) corresponding to the two-fluid model with noncondensable(s) used in RELAP5/MOD3.2. This validation has been carried out by using sample problems involving (a) a liquid phase only, (b) a gas phase only, and (c) a two-phase mixture (of water and steam). Thus, the 'Two-Loops with Pumps' sample problem supplied with RELAP5/MOD3.2 has been used to verify the accuracy and stability of the numerical solution of the ASM-REL/TF when only the liquid phase is present. Furthermore, the 'Edwards Pipe' sample problem, also supplied with RELAP5/MOD3.2, has been used to verify the accuracy and stability of the numerical solution of the ASM-REL/TF when both (i.e., liquid and gas) phases are present. In addition, the accuracy and stability have been verified of the numerical solution of the ASM-REL/TF when only the gas phase is present by using modified 'Two-Loops with Pumps' and the 'Edwards Pipe' sample problems in which the liquid- and two-phase fluids, respectively, were replaced with pure steam. The results obtained for these sample problems depict typical sensitivities of junction velocities and volume-averaged pressures to perturbations in initial conditions and indicate that the numerical solution of the ASM-REL/TF is as robust, stable, and accurate as the original RELAP5/MOD3.2 calculations.This work also illustrates the role that sensitivities of the thermodynamic properties of water play for sensitivity analysis of thermal-hydraulic codes for light water reactors. The well-known 1993 ASME Steam Tables are used to present typical analytical and numerical results for sensitivities of the thermodynamic properties of water to the numerical parameters that appear in the mathematical formulation of these properties. Particularly highlighted are the very large sensitivities displayed by the specific isobaric fluid and gas heat capacities C_pf and C_pg, respectively; the specific fluid enthalpy h_f; the specific gas volume V_g; the volumetric expansion coefficient for gas β_g; and the isothermal coefficient for gas k_g. The dependence of β_g and k_g on the most sensitive parameters turns out to be nonlinear, while the dependence of C_pf, C_pg, h_f, and V_g on the most sensitive parameters turns out to be linear, so the respective sensitivities predict exactly the effects of variations in the respective parameters. On the other hand, the sensitivities of the specific fluid volume V_f, the volumetric expansion coefficient for fluid β_f, the specific gas enthalpy h_g, and the isothermal coefficient of compressibility for fluid k_f to the parameters that appear in their respective mathematical formulas are quite small. Finally, it is noted that such deterministically calculated sensitivities can be used to rank the respective parameters according to their importance, to assess the effects of nonlinearities and, more generally, to perform comprehensive sensitivity/uncertainty analyses of thermal-hydraulic codes that use a water substance as the working fluid

[en] Multiregion two-dimensional domains occur in many problems, including reactor core models for neutronics calculations. The geometries typically encountered in such problems are rectangular or hexagonal and typically involve interior corners at the intersections between domains (e.g., homogenized subassemblies) with distinct material properties. The analytical solution of the multigroup neutron diffusion equation (MGDE) at and around such corners has been presented in Ref. 1, where it was shown that the neutron flux for the g'th energy group has the form Φ^gr,θ = Σ_j f_jg (G;r)T_j(g;θ), where G denotes the fact that the functions f_jg depend on the material properties (i.e., diffusion coefficients and cross sections) pertaining to all of the energy groups. Although the expressions for the radial functions f_jg (G; r) were presented, the specific expressions for the angular eigenfunctions T_j (g; θ) were not presented there. This was because these angular eigenfunctions are generally applicable to all elliptical problems (i.e., problems that involve a Laplace-type operator) and not only to the MGDE. It is the purpose of this paper to present the exact expressions of these angular eigenfunctions for two of the most commonly encountered geometries in engineering (including reactor neutronics) problems, namely, three-region hexagonal and four-region rectangular geometry, respectively

No abstract available

[en] This work illustrates the use of the Adjoint Sensitivity Analysis Procedure (ASAP) for the non-equilibrium, non-homogeneous two-fluid model, including boron concentration and non-condensable gases, of the RELAP5/MOD3.2 code. The end-product of applying the ASAP is the Adjoint Sensitivity Model, denoted as ASM-REL/TF, corresponding to the two-fluid flow model in RELAP5/MOD3.2. Typical sensitivities for RELAP5/MOD3.2 parameters are presented by using the 'Two-Loops with Pumps' sample problem supplied with RELAP5/MOD3.2, for both the liquid- and the gas-phase segments of the ASM-REL/TF. (author)

[en] Full text: The design of a new planned FZK experimental facility, Helium Loop Karlsruhe (HELOKA) is presented in this paper. This facility will be dedicated to the testing of various components for nuclear fusion facilities: ITER Test Blanket Module (TBM), ITER Test Divertor Module (TDM), IFMIF High Flux Test Module (HFTM). The design of HELOKA has been elaborated in close co-operation with the future potential users. Based on their requirements, HELOKA is planned to be composed of three sub-loops: HELOKA-Low Pressure for IFMIF/HFTM, HELOKA-High Pressure for TBM and HELOKA-High Pressure for TDM and DEMO with different pressure- and temperature profiles. The facility would be worldwide unique and will offer the opportunity to investigate problems of helium cooling covering a variety of applications in different areas thus offering the possibility of a wide range of co-operations. (author)

[en] This paper presents the thermo-hydrodynamic model used to simulate the behaviour of the HELOKA (Helium Loop Karlsruhe) facility and describes the mechanism used to control various loop parameters. This test facility, which is under construction at the Forschungszentrum Karlsruhe (FZK), is designed for testing of various components for nuclear fusion such as the Helium-Cooled Pebble Bed blanket (HCPB) and the heliumcooled- divertor for the DEMO power reactor. Besides the individual testing of the blanket and divertor modules, the understanding of the behaviour of their cooling systems in conditions relevant for ITER operation is mandatory. An important aspect in the operation of these cooling loops is the accurate control, via feedback, of the flow parameters at the inlet of the test module. Understanding heat transfer and fluid flow phenomena during normal and transient operation of HELOKA is essential to ensure the adequacy of safety features. Systems analysis codes, such as RELAP5-3D, are suited to this task. However, the application of these models to HELOKA design must be later validated by experimental measurements, while the basic physical models have been proven for light water reactors. The control of the test section inlet parameters is one of the most important issues. In particular, the start-up phase, when the test section temperature is increased from ambient temperature up to 300 C, requires special attention. As a first step, the HELOKA open loop thermal transient was computed using the RELAP model. The data obtained have been used for the identification of the power-temperature transfer function needed to compute the parameters of the feedback controller (PID) using MATLAB and SIMULINK. An accurate control of the temperature during the start-up and flat top phases is achieved solely by controlling the heater power. The adopted solution reduces the harmonic distortions when operating at reduced power while keeping the investment cost low. This control has been implemented back into the RELAP model of HELOKA. Qualitatively, RELAP5-3D's predictions agree closely with those of the other system codes. Quantitatively, RELAP5-3D computes slightly higher temperature oscillations at the inlet of the TBM than the other system analysis. (orig.)

[en] The properties of short-lived isomeric states in ¹¹⁹Sb and ¹¹²In, populated in the reactions ¹¹⁸Sn(d,n), ¹¹⁹Sn(d,2n), ¹¹²Cd(d,2n) and ¹⁰⁹Ag(α,n), have been investigated by pulsed beam γ-ray spectroscopy and TDPAD method. A new 19/2 - 136 ns isomeric state has been identified at 2553.3 keV in ¹¹⁹Sb and the intruder configuration [π(1g_9/2^-1)·ν(1h_11/2 2d_3/2)7^-] 19/2^- has been assigned to it on the basis of the measured g-factor, g_exp=+0.331(6). Experimental information concerning the decay scheme of the short-lived isomeric states in ¹¹²In has been obtained. A new 6.32 keV M1 transition has been observed in this decay scheme and a mixed E1+5%M2 multipolarity has been assigned to the known 263 keV isomeric transition.(authors)