SYSTEM FOR VESSEL NUCLEAR REACTOR CONTROL AND TWO-POSITION SWITCH OF THE PASSIVE PROTECTION OF A NUCLEAR REACTOR (NR) Russian patent published in 2005 - IPC

FIELD: control systems of nuclear reactors.

SUBSTANCE: the proposed vessel NR control system has a set of technical means for limitation of the reactivity increase rate by means of operating elements (OE) and for automatic shutdown of NR. The set has drives with motors and braces, transmitting the motion from drive motors to OE, located within the NR vessel. In this case immobile members for engagement and uncoupling with OE are installed within the NR vessel. The design ensures the possibility of OE movement by total forces, constantly acting on OE after their uncoupling only in the direction of decreasing the reactivity. Every OE is equipped at least with two drives. One of them is common for all OE or common for a group of OE. This drive moves OE in the direction of reactivity increase up to engagement with immobile members only in turn one by one after engagement of the brace of its motor with the selected OE. Other drive, individual for every OE, uncouples the OE with a given immobile member in any order in relation to other OE by uncoupling the brace of its motor with the OE engagement member with the given immobile member. The set of technical means is equipped with two-position switches, located within the NR vessel. The switches have two fixed states in dependence on the position of the control element of a switch in respect to the critical element, which corresponds to achieving the critical value of one of parameters, determining the NR safe operation limits. Braces of motors of individual drives with engagement members are equipped with controlled elements of break, for example of the type of a clutch. The controlled elements ensure the possibility of breaking the braces for OE motion in direction of reactivity decrease in the case, when the state of two-position switches corresponds to achieving the critical values of parameters, determining the limits of NR safe operation. The braces of motors of total drives with OE are equipped with breaking elements, for example, of the type of clutch. The breaking elements are located within the NR vessel joint and ensure the possibility of brace break when releasing the NR vessel joint. The control elements of two-position switches ensure possibility of motion of control elements by means of total drive after engagement of the brace of its motor with a chosen control element only in direction, ensuring OE motion in direction of reactivity decrease. As a result possibility of NR operation transition in the mode with violation of the safe operation limits is excluded for the NR diversion control, limited by 16 hours. In this case it is possible exclusion of prolonged longitudinal disturbances of the neutron field, conditioned by OE in the form of rods, being in intermediate positions after their longitudinal motion. Two-position switch of the NR passive protection has two fixed state in dependence on the switch control element position in respect to the critical position. This position corresponds to achieving the critical value of one of parameters, determining the limits of NR safe operation. In the case the control element design ensures possibility of transition of two-position switch from one fixed state into other one (operation) when achieving the critical value of the following parameters: temperature elongation of the NR fuel elements (FE) and/or NR coolant density and/or corrosion activity of NR coolant.

EFFECT: increased speed of response and sensitivity of two-position switch when achieving the critical value of FE temperature; prevention of the FE superheating during loss of coolant in NR; increased NR safety when rising the NR coolant corrosion activity.

8 cl, 1 dwg