The present invention relates to a method for extending the lifespan of rhodium measuring devices. To this end, the method comprises the steps of: measuring current signals, expressed in amperes, which are induced by electrons emitted as a result of rhodium, in each rhodium measuring device, undergoing beta decay as a result of absorbing neutrons (S10); on the basis of the current signals, and by using a CECOR program, calculating, for each rhodium burnup, respective positional output values of the individual rhodium measuring devices (S20); calculating, for each rhodium burnup, an optimal output value for all positions (S30); determining a W′ correction constant, or a change in an exponent of an approximate expression of the sensitivity of the rhodium measuring devices (S40); calculating, for each rhodium burnup, respective positional output values of the individual rhodium measuring devices, and checking same by carrying out a comparative analysis between same and the respective positional output values of the rhodium measuring devices, calculated in S20 (S50); and extending the lifespan of usage of the rhodium measuring devices by applying the W′ correction constant, or the exponent of the approximate expression of sensitivity, at the time point when ⅔ or more of the rhodium in the rhodium measuring devices is burned up (S60).

The present invention relates to a top nozzle and a nuclear reactor in which an in-core instrument, which is supposed to be inserted through a top head of a nuclear reactor, is inserted through a guide pin for an upper core plate. In a nuclear reactor including guide pins for aligning a top nozzle for a nuclear fuel assembly with an upper core plate of a nuclear reactor, a guide hole (210) is axially formed through the guide pins (200) and in-core instruments (10) are inserted through the guide holes (210).

Illustrative embodiments provide a nuclear fission reactor, that includes a reactor vessel, a nuclear fission fuel element capable of generating a gaseous fission product, a valve body defining a plenum for receiving the gaseous fission product, and a valve in operative communication with the plenum for controllably venting the gaseous fission product from the plenum.

A sensor system for a fuel rod including a fuel pellet stack, the sensor system including a wireless interrogator disposed outside the fuel rod and a passive sensor component disposed within the fuel rod. The passive sensor component includes a receiver structured to receive an interrogation signal and output an excitation signal in response to receiving the interrogation signal, a reference transmitter structured to output a reference signal to the reference receiver in response to the excitation signal, a sensing transmitter structured to output a sensing signal to the sensing receiver in response to the excitation signal, and a core at least partially disposed within the sensing transmitter and coupled to move in conjunction with expansion or contraction of the fuel pellet stack, to move based on changes in pressure within the fuel rod, or to change temperature based on temperature changes within the fuel rod.

An optical fiber-based gamma-ray calorimeter (OFBGC) sensor array which uses a thermal mass with a low thermal conductivity is provided. Advantages of the OFBGC sensor array include: 1) the number of sensors in the OFBGC sensor array is adjustable and limited only by the spatial resolution of the OFBGC sensors, within the OFBGC sensor array, and 2) the OFBGC sensor design is simpler to build than a conventional optical fiber-based gamma thermometer (OFBGT) sensor array. One purpose of the OFBGC is to determine the power distribution in nuclear reactors.

The present disclosure relates to a method for monitoring failure of coated particles in fuel elements in a core of a pebble-bed high-temperature gas-cooled reactor, which is related to the technical field of nuclear reactor engineering and includes the following steps: S11, calculating an inventory of a short-lived noble gas fission nuclide; S12, obtaining a ratio of a release rate to a birth rate of the short-lived noble gas fission nuclide based on a temperature of the fuel elements using a Booth diffusion and release model; S13, deriving a theoretical expression for an activity concentration of the short-lived noble gas fission nuclide in a primary circuit using a migration model of the nuclide in the primary circuit; S14, obtaining an experimental measurement value of the activity concentration of the short-lived noble gas fission nuclide in the primary circuit at a sampling moment by gas sampling; S15, optimally calculating a failure fraction of the coated particles in the fuel elements and a share of uranium contamination in the matrix graphite in the core based on the theoretical expression and the experimental measurement value. The present disclosure can provide key parameters for the performance and status of the fuel elements in the core, which are required for radiation safety studies, source term calculations and accident analysis of the pebble-bed high-temperature gas-cooled reactor.

A detector for generating an electrical current that is proportional to a flux of neutrons includes a neutron sensitive emitter, a conductive collector, an insulator between the neutron-sensitive emitter and the collector, an electrical connection to the neutron sensitive emitter, and an electrical connection to the conductive collector. The neutron sensitive emitter includes an emitter material with no more than 2 stable isotopes, and which upon impact by a neutron having an energy of from 100 keV to 1000 keV will generate electrons in proportion to the flux of neutrons in less than 10 minutes, and any generated electrons not generated in less than 10 minutes will be generated in no less than 30 days. A method of detecting neutrons generated by a nuclear reactor is also disclosed.

A defective fuel bundle location system for use with a heavy water moderated nuclear fission reactor having a fueling machine, including a test tool defining an internal volume, the test tool being configured to be received within both the fueling machine and a corresponding fuel channel of the reactor, and a test container defining an internal volume, wherein the test container is configured to be received within the internal volume of the test tool and the internal volume of the test container is configured to receive primary fluid from the reactor when the test tool is disposed within the corresponding fuel channel of the reactor.

A defective fuel bundle location system for use with a heavy water moderated nuclear fission reactor having a fueling machine, including a test tool defining an internal volume, the test tool being configured to be received within both the fueling machine and a corresponding fuel channel of the reactor, and a test container defining an internal volume, wherein the test container is configured to be received within the internal volume of the test tool and the internal volume of the test container is configured to receive primary fluid from the reactor when the test tool is disposed within the corresponding fuel channel of the reactor.

A nuclear system. The nuclear system includes a fuel rod for use in a nuclear reactor. The fuel rod includes a cladding comprising an interior region, unspent fuel pellets housed in the interior region of the cladding, and a resonant electrical circuit supported within the interior region of the cladding. The resonant electrical circuit is configured to receive an excitation pulse through the cladding, and responsive to the received excitation pulse, generate a response pulse in the form of a magnetic field signal that is structured to travel wirelessly from the interior region and through the cladding. The nuclear system also includes a receiver positioned outside of the cladding and within the nuclear reactor. The receiver is configured to receive the response pulse and generate an output based on the received response pulse.