Abstract: A rhodium self-powered detector, a fission chamber, and appropriate electronic circuitry for combining the output of the self-powered detector and the fission chamber are disclosed in combination wherein the combined output of the self-powered detector and the fission chamber is always proportional to the local reactor power level or neutron flux density in a nuclear reactor.

Abstract: A universal logic card is disclosed which contains both pre-programmed functional circuitry for actuating channel logic and dedicated test circuitry for system controller test and for constant and looping interrogation of the pre-programmed channel logic in absence of self-test system controller test. The disclosed card resides as a channel in a self-test system for a nuclear power plant supplementing the nuclear reaction protection system. The card is pre-programmed in digital logic to act equivalent to an analog circuit during actual plant operation. Additionally, the card responds to system controlled surveillance of the nuclear protection system. In system controlled surveillance, a central microprocessor serially addresses system circuit cards such as the one disclosed and loads these cards at predetermined input points with test commands. The addressed cards are thereafter simultaneously activated by a system-wide command.

Abstract: A fission chamber detector system for monitoring neutron flux density in a nuclear reactor includes a preamplifier and signal conditioning unit for amplifying and conditioning neutron signal pulses produced by fission chamber detectors located adjacent the reactor core. The preamplifier and signal conditioning unit are located outside of the containment vessel for the reactor. The amplifier and signal conditioning unit amplify and condition the neutron signal pulses to provide signals that can be transmitted by twisted shielded pairs to a remotely located signal processing unit. The preamplifiers include an input stage that enables the preamplifiers to be controlled remotely to either pass or inhibit neutron signal pulses to an amplifier stage from the fission chambers, and to pass test signals to the amplifier stage.

Abstract: A logic safety system is disclosed having four redundant channels with each channel constituted by a logic circuit for controlling the triggering of a protective action, a logic alarm circuit connected to the control circuit and a logic inhibition circuit which makes it impossible to simultaneously inhibit several alarm circuits. Any attempt at inhibiting the alarm circuit of a second channel while an alarm circuit of a first channel is already inhibited will result in the automatic appearance of a protective action control signal at the output of the second channel regardless of the signal received at the input of the alarm circuit of the second channel.

Abstract: A self-test system for a nuclear power plant, nuclear reactor protection system is disclosed. Nuclear protection systems are the electronic controls, typically including circuit cards, located intermediate between sensors (as for detecting core overheat) and a control (as for providing rod injection to shut down a reactor). Constant surveillance of the nuclear system protection system is provided by a microprocessor that serially addresses protection system circuit cards and loads them at pre-determined input points with test commands. The addressed cards are thereafter simultaneously activated by a system-wide command. The test command is a pulse which is so short in duration that its affect is transparent to the system and cannot cause overall system operation. The pulse passes through the actuating electrical components to verify, on the real actuating path, the operating integrity of the system.

Abstract: The invention relates to a method for testing fuel element tubes by ultrasonic energy. For testing, each tube becomes disposed in the space between a transmit transducer and a receive transducer. The echo signals falling within a predetermined time interval are evaluated. Since the distance between the transducers may vary as the transducers move through the space between fuel element tubes, the transmitted signal reaching the receive transducer without passing through the tube may be confused with the revolving echo signal. Therefore, this invention discloses an arrangement for cyclically controlling the setting of the time gate before each such tube is in position between the transducers. To this end, the ultrasonic transit time of signals between the transmit transducer and the receive transducer is measured in the gap between the last tested tube and the next to be tested tube.

Abstract: A method and apparatus for determining the subcriticality of masses of uranium by directing epithermal neutrons toward said mass, isolating said material from external thermal neutrons, and measuring the ratio of thermal and epithermal neutrons to epithermal neutrons which enables the establishment of a subcriticality value representative of the mass of uranium.

Abstract: Direct power shape monitoring in parallel with precision power monitoring is effected by use of gamma sensors in the fuel core and signal processing that includes compensation for slow signal response and takes advantage of a substantially direct relationship of sensor signal to linear power generation rate. Continuous readout from the direct power shape monitor is available during readout interruptions in the precision monitor.

Abstract: A fission chamber detector system for monitoring neutron flux density in a nuclear reactor utilizes a unique coaxial cable carried through a flexible metal hose to provide sufficient signal quality to allow a preamplifier and signal conditioning unit for amplifying and conditioning neutron signal pulses produced by the fission chambers to be far enough away from the fission chambers as to be located outside of the containment vessel for the reactor. Reactor power and rate-of-reactor-power-change signals produced for overlapping power ranges from a countrate circuit and a mean square voltage circuit are aligned by a voltage controlled switch and a slave switch without causing spurious transients in the rate-of-change signals. Power signal indications are provided over 12 decades.

Abstract: A preamplifier for a wide range neutron flux monitoring system is disclosed. The preamplifier contains first to fifth amplifiers and a selection switch. The first amplifier for high frequency band amplification has a low input impedance circuit. The second amplifier for low frequency band amplification has a high input impedance circuit. Either of the first and second amplifiers can provide a path for the neutron flux level signal derived from a detector according to the frequency of the neutron flux level signal. The third amplifier (pulse amplifier) amplifies the output signal of the first amplifier and transfers the amplified signal to a pulse signal counting system. The lower frequency band Campbell signal is applied to the Campbelling system, through the second amplifier, the fourth amplifier (low frequency band Campbelling amplifier), and the selection switch.

Abstract: A trip system comprises groups of three switches, each group being responsive to a single trip initiating event and each switch switching a different phase of a three phase power supply. Three trip actuators are each connected between different pairs of switches. Malfunction of a single switch in any group will not cause a trip to occur while concurrent operation of two or more switches in any group will cause a trip.

Abstract: Each parameter of the processes of the nuclear reactor and of the components of a power supply which convert the thermal energy generated by the reactor into electrical power is monitored by a set of four like sensors. One each of the unlike sensors which monitor the different parameters is contained in a reactor-trip logic channel. Each such unlike sensor is referred to here as a "local sensor". Each channel is interlocked with the other three channels and receives the signals sensed by the other three sensors, herein called "remote sensors". Each channel also includes means for processing the signals from the local and remote sensors. The apparatus also includes means for tripping the reactor to deenergize or trip the control rod drive and insert the control rods fully into the core so that the reactor stops supplying power. The apparatus normally operates on a "two out of four" configuration. This assumes that all sensors are in normal operating condition.

Abstract: The redundant signals from the sensor assemblies measuring the process parameters of a nuclear reactor power supply are transmitted each in its turn to a protection system which operates to actuate the protection apparatus for signals indicating off-process conditions. Each sensor assembly includes a number of like sensors measuring the same parameters. The protection system has a number of separate protection units, each unit receiving the process signals from the like sensors of each assembly in its turn. The sets of process signals derived from the sensor parameter assemblies are each in its turn transmitted from the protection system to the control system which impresses control signals on the reactor or its components to counteract the tendency for conditions to drift off-normal status requiring operation of the protection system. A parameter signal selector is interposed between the protection system and the control system.

Abstract: A control system for coupling redundant logic channels while maintaining electrical and physical isolation between channels. The separate redundant logic channels each include an electro-optic modulator, which are connected by fiber optic links, with system condition sensors generating signals which are applied to the electro-optic modulators to control the light transmission characteristics of the electro-optic medium in response to a predetermined system condition. A light source is connected by input fiber optics to the logic channels, and output fiber optics connect the logic channels to a light detector.

Abstract: In a neutron detector of the type comprising an ionization chamber provided with anode and cathode electrodes for detecting neutron flux injected into the ionization chamber, and a cable including a central conductor connected to the anode or cathode electrode and the outer conductor connected to the cathode or anode electrode there are provided an intermediate insulated annular conductor arranged between the inner and outer conductors of the cable, and upper and lower insulated annular conductors disposed between the anode and cathode electrodes for supporting one of them. The upper and lower insulated annular conductors are electrically interconnected and the upper insulated annular conductor is connected to the intermediate annular conductor of the cable.