Qualifizierung des Kernmodells DYN3D im Komplex mit dem Störfallcode ATHLET als fortgeschrittenes Werkzeug für die Störfallanalyse von WWER-Reaktoren - Teil 2

Benchmark calculations for the validation of the coupled neutron kinetics/thermohydraulic code complex DYN3D-ATHLET are described. Two benchmark problems concerning hypothetical accident scenarios with leaks in the steam system for a VVER-440 type reactor and the TMI-1 PWR have been solved. The first benchmark task has been defined by FZR in the frame of the international association "Atomic Energy Research" (AER), the second exercise has been organised under the auspices of the OECD. While in the first benchmark the break of the main steam collector in the sub-critical hot zero power state of the reactor was considered, the break of one of the two main steam lines at full reactor power was assumed in the OECD benchmark. Therefore, in this exercise the mixing of the coolant from the intact and the defect loops had to be considered, while in the AER benchmark the steam collector break causes a homogeneous overcooling of the primary circuit. In the AER benchmark, each participant had to use its own macroscopic cross section libraries. In the OECD benchmark, the cross sections were given in the benchmark definition. The main task of both benchmark problems was to analyse the re-criticality of the scrammed reactor due to the overcooling. For both benchmark problems, a good agreement of the DYN3D-ATHLET solution with the results of other codes was achieved. Differences in the time of re-criticality and the height of the power peak between various solutions of the AER benchmark can be explained by the use of different cross section data. Significant differences in the thermohydraulic parameters (coolant temperature, pressure) occurred only at the late stage of the transient during the emergency injection of highly borated water. In the OECD benchmark, a broader scattering of the thermohydraulic results can be observed, while a good agreement between the various 3D reactor core calculations with given thermohydraulic boundary conditions was achieved. Reasons for the differences in the thermohydraulics were assumed in the difficult modelling of the vertical once-through steam generator with steam superheating. Sensitivity analyses which considered the influence of the nodalisation and the impact of the coolant mixing model were performed for the DYN3D-ATHLET solution of the OECD benchmark. The solution of the benchmarks essentially contributed to the qualification of the code complex DYN3D-ATHLET as an advanced tool for the accident analysis for both VVER type reactors and Western PWRs

Methodenentwicklung zur Analyse von Störfallszenarien mit Frischdampfleck und Borverdünnung mit Hilfe des Codesystems ATHLET-DYN3D - Abschlussbericht Teil 2

Es wurde ein Modell zur realistischen Beschreibung der Kühlmittelvermischung innerhalb des Reaktordruckbehälters von Druckwasserreaktoren in den gekoppelten Programmkomplex DYN3D/ATHLET implementiert. Diese Modell basiert auf dem Prinzip der linearen Superposition Dirac-Impuls-ähnlicher Störungen und kann für die Modellierung der Vermischung von Kühlmittel unterschiedlicher Temperatur und/oder unterschiedlicher Borsäurekonzentration eingesetzt werden. Der um das Vermischungsmodell erweiterte Programmkomplex DYN3D/ATHLET wurde für Analyse von Borverdünnungsstörfällen und Frischdampflecks angewandt. Für den Fall "Start der ersten Hauptkühlmittelpumpe bei Vorhandensein eines minderborierten Pfropfens im kalten Strang" zeigten die Ergebnisse der durchgeführten Parameterstudie, dass es selbst bei Annahme des maximal möglichen Pfropfenvolumens nicht zu einer Schädigung des Brennstoffes kommt. Mit den Analysen zu einem generischen Frischdampfleckszenario wurde die Anwendbarkeit des Programmkomplexes DYN3D/ATHLET auf die zweite Störfallklasse, in der die Kühlmittelvermischung eine wichtige Rollen spielt, demonstriert. Im Rahmen der Arbeiten zum Projekt wurde außerdem gezeigt, dass der Einfluss der turbulenten Schwankungen des Geschwindigkeitsfeldes innerhalb des Reaktordruckbehälters auf neutronenkinetische Parameter im Nominalbetrieb und unter Störfallbedingungen nicht zu vernachlässigen ist. A model for the realistic description of the coolant mixing inside the pressure vessel of pressurized water reactors was implemented into the coupled code complex DYN3D/ATHLET. This model is based on the linear superposition Dirac-pulse-like perturbations. The model can be applied to the mixing of coolant of different temperature and/or boron concentration. The coupled code complex DYN3D/ATHLET with the newly implemented model was applied to the analysis of boron dilution and steam line break accidents. The results of a parameter study for the case "Start-up of the first main coolant pump with a slug of lower borated water in the cold leg" have shown, that even under the conditions of the maximum slug volume there is no fuel damage. The applicability to the second class of accidents, where the coolant mixing has to be considered, was demonstrated by the analysis of a generic main steam line break scenario. Further it was shown, that the influence of turbulent fluctuations of the velocity inside the reactor pressure vessel during nominal and accident conditions on neutron-kinetic parameters cannot be neglected

Verification of the code DYN3D for calculations of neutron flux fluctuations

Insufficiently explained magnitudes and patterns of flux fluctuation observed mainly in KWU PWRs are recently investigated by various European institutions. Among the numerical tools used to investigate the\ua0neutron flux\ua0fluctuations is the time-domain reactor dynamics code\ua0DYN3D. As\ua0DYN3D\ua0and comparable codes have not been developed with the primary intention to simulate low-amplitude neutron flux fluctuations, their applicability in this field has to be verified.In order to contribute to the verification of\ua0DYN3D\ua0for the simulation of neutron flux fluctuations, two special cases of perturbations of the neutron flux (a localized absorber of variable/oscillatory strength and a travelling oscillatory perturbation) are considered with\ua0DYN3D\ua0on the one hand and with the frequency-domain neutron noise tool\ua0CORE SIM\ua0as well as analytical frequency-domain approaches, respectively, on the other hand. The obtained results are compared with respect to the distributions of the amplitude and the phase of the induced neutron flux fluctuations. The comparisons are repeated with varied amplitudes and frequencies of the perturbation.The results agree well both qualitatively and quantitatively for each of the conducted calculations. The remaining deviations between the\ua0DYN3D\ua0results and the reference results exhibit a dependence on the perturbation magnitude, which is attributed to the neglect of higher-order terms (linear theory) of the perturbed quantities in the calculation of the reference solutions

Sociocultural Competence Training in Higher Engineering Education: The Role of Gaming Simulation

The present study focuses on competency-based approach in higher engineering education. Today engineers are required to be socially, culturally and communicatively skilled and able to act in constantly changing sociocultural environment. Presently the development of engineers’ sociocultural competency is of great importance, which is seen from the criteria for accrediting engineering programs of numerous international organizations, e.g. ABET. The paper presents some methods of sociocultural competency training based on the techniques of gaming simulation. Here we describe the educational games “Intercultural communication” and “The art of presentation” for the students of Elite Education Department of National Research Tomsk Polytechnic University. The results of incorporating the gaming technologies in education contribute to the effectiveness of engineers’ sociocultural competency training. The paper ends by pointing out gaming simulation which is a cutting-edge pedagogical approach which allows students to participate in realistic scenarios and develop sociocultural competency

Emotional Processing, Interaction Process, and Outcome in Clarification-Oriented Psychotherapy for Personality Disorders: A Process-Outcome Analysis.

It is important to understand the change processes involved in psychotherapies for patients with personality disorders (PDs). One patient process that promises to be useful in relation to the outcome of psychotherapy is emotional processing. In the present process-outcome analysis, we examine this question by using a sequential model of emotional processing and by additionally taking into account a therapist's appropriate responsiveness to a patient's presentation in clarification-oriented psychotherapy (COP), a humanistic-experiential form of therapy. The present study involved 39 patients with a range of PDs undergoing COP. Session 25 was assessed as part of the working phase of each therapy by external raters in terms of emotional processing using the Classification of Affective-Meaning States (CAMS) and in terms of the overall quality of therapist-patient interaction using the Process-Content-Relationship Scale (BIBS). Treatment outcome was assessed pre- and post-therapy using the Global Severity Index (GSI) of the SCL-90-R and the BDI. Results indicate that the good outcome cases showed more self-compassion, more rejecting anger, and a higher quality of therapist-patient interaction compared to poorer outcome cases. For good outcome cases, emotional processing predicted 18% of symptom change at the end of treatment, which was not found for poor outcome cases. These results are discussed within the framework of an integrative understanding of emotional processing as an underlying mechanism of change in COP, and perhaps in other effective therapy approaches for PDs