A method for checking the functional equivalence of two pieces of software for control systems, in particular control systems based on programmable logic controllers, engineered from function block diagrams (120, 196) with a plurality of interconnected function blocks, the method comprising the following steps: a) generating a first instance of compilable source code from a first plurality of function block diagrams (70, 74, 78) by virtue of a first code generator obeying to a first set of sequentialization rules; b) parsing said first instance of source code and identifying the set of all function block I/O ports and junction points (nodes) and the set of all connections between them (arcs) of the data flow; c) using the information from step b) to reconstruct a first data flow graph (86) of said first instance of source code in the upstream direction; d) generating a second instance of compilable source code from a second plurality of function block diagrams (90, 94, 98) by virtue of the same or a second code generator obeying a second set of sequentialization rules; e) parsing said second instance of source code and identifying the set of all function block I/O ports and junction points (nodes) and the set of all connections between them (arcs) of the data flow; f) using the information from step e) to reconstruct a second data flow graph (106) of said second instance of source code in the upstream direction; g) comparing said first identified data flow graph (86) and said second identified data flow graph (106) with each other, node by node, and thereby checking if the transitive closure of input up to that node in said second instance of source code is the same as in said first instance of source code.
The invention relates to a fan arrangement (2) with a plurality of ventilators (4) which are arranged parallel to one another and are designed to generate an air flow along a common main flow direction (6), wherein • at least one flow channel (10) is paired with each ventilator (4), • each flow channel (10) is provided with a flap (14) which can be pivoted between an open position and a closed position, and • each flap (14) is constructed and arranged in the flow channel (10) so as to be supported by the air flow in the open position and so as to be brought into the closed position by a reverse flow directed opposite the air flow. The aim of the invention is to reliably prevent a flow short-circuit in the event that individual ventilators (4) malfunction and to ensure a natural draft convection in the event that all ventilators (4) malfunction. According to the invention, this is achieved in that each flap (14) is constructed so as to be brought into the open position by virtue of its inherent weight in the absence of a flow.
The invention relates to a seismic sensor unit (4) for an emergency shutdown system (2) of a nuclear power plant, comprising - at least one accelerometer (6) for at least one axis, - a trigger module (8) which processes a signal derived from a measured signal of said accelerometer (6) and generates an output signal from which a trip signal is derived. It is an objective of the present invention to provide a reliable, robust, and non- complex seismic sensor unit (4) of such a type. The proposed solution according to the invention is characterized in that said trigger module (8) comprises an analog peak-hold-circuit (18) processing an input signal (X) and generating an output signal (Y) with the following properties: - if the input signal (X) is rising and the level of the output signal (Y) is below the level of the input signal (X), the output signal (Y) increases almost in- stantly with the input signal (X), - if the level of the input signal (X) is below the level of the output signal (Y), the output signal (Y) essentially keeps the current level unless a reset condition is reached.
A circuit arrangement, in particular for a safety I&C system (4) of a nuclear power plant (6), is to keep the proven diagram-centric project-specific engineering approach known from CPU-based systems while reaping the benefits of FPGA technology. To this end, the circuit arrangement according to the invention comprises: • a generic FPGA (18) with a number of logic blocks (20), and • at least one dedicated PLD (22) which operates as an application-specific switch-matrix for said logic blocks (20).
H03K 19/177 - Logic circuits, i.e. having at least two inputs acting on one outputInverting circuits using specified components using elementary logic circuits as components arranged in matrix form
The invention is principally directed to a reduced order model, XEDOR, facilitating the prediction of and the diagnostics of pellet-clad interaction stress-corrosion-cracking failure of nuclear fuel rods. The invention more particularly relates to assessment of susceptibility to PCI failure for guidance in the design of fuel loading in nuclear reactors. The invention additionally relates to the protection against PCI failure by providing operational information to operators of a nuclear reactor during power maneuvering, including predictive calculations prior to executing power maneuvers. Additionally, the invention relates to the diagnostics of an event suggesting a possible PCI cladding failure.
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