Study of an intrinsically safe infrastructure for training and research on nuclear technologies

Within European Partitioning & Transmutation research programs, infrastructures specifically dedicated to the study of fundamental reactor physics and engineering parameters of future fast-neutron-based reactors are very important, being some of these features not available in present zero-power prototypes. This presentation will illustrate the conceptual design of an Accelerator-Driven System with high safety standards, but ample flexibility for measurements. The design assumes as base option a 70MeV, 0.75mA proton cyclotron, as the one which will be installed at the INFN National Laboratory in Legnaro, Italy and a Beryllium target, with Helium gas as core coolant. Safety is guaranteed by limiting the thermal power to 200 kW, with a neutron multiplication coefficient around 0.94, loading the core with fuel containing Uranium enriched at 20% inserted in a solid-lead diffuser. The small decay heat can be passively removed by thermal radiation from the vessel. Such a system could be used to study, among others, some specific aspects of neutron diffusion in lead, beam-core coupling, target cooling and could serve as a training facility

Object-oriented modelling and simulation for the ALFRED dynamics

In this paper, a control-oriented modelling and simulation tool for the study of the Advanced Lead-cooled Fast Reactor European Demonstrator (ALFRED) plant dynamics is presented. It has been developed in order to perform design-basis transient analyses aimed at providing essential feedbacks for the system design finalization. The simulator has been meant to be modular, open and efficient. In this perspective, an object-oriented modelling approach has been adopted, by employing the reliable, tested and well documented Modelica language. Simulation of core behaviour is based on point kinetics for neutronics and one-dimensional heat transfer models for thermal-hydraulics, coherently with ALFRED specifications. An effort has been spent to model the bayonet-tube Steam Generator (SG) foreseen to be installed within the reactor vessel. The primary loop model has been built by connecting the above-mentioned components (taking into account suitable time delays) and by incorporating the cold pool, which has revealed to be fundamental for an accurate definition of the time constants characteristic of the system because of its large thermal inertia. The description of the overall plant has been finalized by connecting standard turbine, condenser and other components of the balance of plant. Afterwards, the reactor responses to three typical transient initiators have been simulated (i.e., reduction of feedwater mass flow rate, variation of the turbine admission valve coefficient and transient of overpower). Simulation outcomes confirm the strong coupling between core and SG, besides showing the characteristic time constants of the various component responses. Results of the present study constitute a starting point in the definition of plant control strategies, laying the basis for investigation and development of a model-based control-system design

Optimal implementation of dagger sampling variance-reducing techniques in Monte Carlo reliability analysis

(abstract only

Modeling and Experimental Tests on the Hydraulically Driven Control Rod Option for IRIS Reactor

Pittsburgh, PA (USA

An Object Oriented Approach to Simulation of Triga Mark II Dynamic Response

This paper deals with the development of a model for the nuclear research reactor TRIGA Mark II operating at University of Pavia. The purpose of the modeling is to reproduce the dynamic behavior of the reactor on the entire operative power range, i.e. 0÷250 kW, using the object oriented approach, implemented by the Modelica language. The main advantage is the a-causal formulation of the model, based on equations instead of statement assignment

A Zero Dimensional Model for Simulation of Triga Mark II Dynamic Response

In this paper the development of a model for the nuclear research reactor TRIGA Mark II operating at University of Pavia is presented. Purpose of the modeling is to reproduce the dynamic behavior of the reactor on the entire operative power range, i.e. 0÷250 kW. A zero dimensional approach is accounted for and the coupling between neutronics and thermal-hydraulics in natural circulation is considered

Study of a new Automatic Reactor Power Control for the TRIGA Mark II Reactor at University of Pavia

Abstract—The installation of a new Instrumentation and Control (I&C) system for the TRIGA MARK II reactor at University of Pavia has recently been completed in order to assure a safe and continuous reactor operation for the future. The intervention involved nearly the whole I&C system and required a channelby- channel component substitution. One of the most sensitive part of the intervention concerned the Automatic Reactor Power Controller (ARPC) which permits to keep the reactor at an operator-selected power level acting on the control rod devoted to the fine regulation of system reactivity. This controller installed can be set up using different control logics: currently the system is working in relay mode. The main goal of the work presented in this paper is to set up a Proportional-Integral-Derivative (PID) configuration of the new controller installed on the TRIGA reactor of Pavia so as to optimize the response to system perturbations

Development of a power plant simulator

This deliverable aims at developing a simplified MSFR power plant simulator, according to an "object-oriented" modelling approach. This simulator will allow analyzing the dynamic behavior of the overall plant, by involving the fuel circuit, the balance of plant and the electrical grid connection. The plant simulator will then allow the definition and assessment of the operation procedures for the MSFR and the main control strategies of the reactor. The deliverable consists of the code itself, the present document being dedicated to a brief description of this system code, the modeling approaches and preliminary results obtained

An intrinsically safe facility for forefront research and training on nuclear technologies — Kinetics and dynamics

In this paper the current status of the study of the dynamical behaviour of the proposed ADS is presented; it is a complex multi-physics problem which, in the present case of a very low k eff system, is conveniently analyzed because the characteristic time scales of the problem are well separated. To be more specific, time scales of the neutronic (prompt) response of the system are so short to be negligible when studying thermal, mechanical and hydraulic aspects