Abstract: This invention teaches improved apparatus for the method of detecting a breach in cladded fuel used in a nuclear reactor. The detector apparatus is located in the primary heat exchanger which conveys part of the reactor coolant past at least three separate delayed-neutron detectors mounted in this heat exchanger. The detectors are spaced apart such that the coolant flow time from the core to each detector is different, and these differences are known. The delayed-neutron activity at the detectors is a function of the delay time after the reaction in the fuel until the coolant carrying the delayed-neutron emitter passes the respective detector. This time delay is broken down into separate components including an isotopic holdup time required for the emitter to move through the fuel from the reaction to the coolant at the breach, and two transit times required for the emitter now in the coolant to flow from the breach to the detector loop and then via the loop to the detector.

Abstract: The invention provides an apparatus and method for diagnosing breached fuel elements in a nuclear reactor. A detection system measures the activity of isotopes from the cover-gas in the reactor. A data acquisition and processing system monitors the detection system and corrects for the effects of the cover-gas clean up system on the measured activity and further calculates the derivative cure of the corrected activity as a function of time. A plotting system graphs the derivative curve, which represents the instantaneous release rate of fission gas from a breached fuel element.

Abstract: Core cover plug for a liquid metal-cooled nuclear reactor.It comprises a structure constituted in part by suspension elements fixed to the lower plate of the small rotary plug, and in part by control rod sleeve elements and a conical deflecting plate positioned directly above the core. The suspension elements, which can either be rod sleeves or rigid tie rods, support the sleeve elements by means of one or more grids constituted by intersecting vertical plates. The deflecting plate, which itself carries a group of sampling tubes, is fixed to certain sleeve elements by a connection permitting radial sliding.

Abstract: A sipping test for detecting defective sheaths in a nuclear fuel assembly is carried out by increasing the pressure of the gases within the sheaths by increasing the temperature. The fission products are released in case of sheath failure. A mixture of water and inert gas is introduced into a hood containing the fuel assembly. Gas and water are separated at the upper portion of the hood and are circulated in distinct loops for continuous detection of the water-soluble fission products and the gas-driven fission products.

Abstract: In the detection of failed fuel in liquid metal cooled nuclear reactors, a helical annular linear induction pump (5,6) electromagnetically pumps coolant in sampling pipes (4) from fuel sub-assemblies of the reactor core to a selector mechanism (9,10) which collects, in turn, the discharge from each sampling pipe (4) for supply to equipment for monitoring for the presence in the coolant of products indicative of fuel failure. The selector mechanism collects the discharge without contacting the sampling pipes (4) and the same pump (5,6) is employed to pump the selected samples via pipe 11 to the monitoring equipment. This pump may also serve to pump a proportion of the bulked sample from the non-selected sampling pipes after discharge into a vessel (7), the bulked sample being conducted through the pump via pipes (13).

Abstract: An end cap with a tag gas capsule adapted to close an end of a cladding tube of a nuclear fuel element and to introduce a tag gas into the fuel element. The end cap is fixed to the tag gas capsule to form a unitary structure. The end cap has a specific shape or description on its outer surface corresponding to information concerning the specific tag gas and the capsule, so that the description or shape of the end cap can identify the specific capsule and the tag gas contained in the capsule.

Abstract: A solid tag material which generates stable detectable, identifiable, and measurable isotopic gases on exposure to a neutron flux to be placed in a nuclear reactor component, particularly a fuel element, in order to identify the reactor component in event of its failure. Several tag materials consisting of salts which generate a multiplicity of gaseous isotopes in predetermined ratios are used to identify different reactor components.

Abstract: A method and apparatus for identifying those fuel rods (32) of a multiple-rod nuclear fuel assembly (30) which contain leaks, are described. The longitudinal position of the leak in the fuel assembly is determined by moving a first test probe (62) longitudinally along the length of the fuel assembly while drawing coolant surrounding the fuel rods into the probe and sampling the radioactive product content of such coolant. The exact position of the leaking fuel rod is then determined by using second (63) and third (64) test probes to logically subdivide the fuel rods of the fuel assembly at such longitudinal position into successively smaller groups while sampling the radioactive content of coolant surrounding the smaller rod groups, until the leaking fuel rod is isolated. A test probe configuration (60) for subdividing and isolating selective groups of the fuel rods for the coolant sampling is disclosed.

Abstract: A method and apparatus for testing characteristics of nuclear fuel pellet interaction with nuclear reactor fuel rod cladding whereby the temperature profile within a nuclear fuel rod is more closely modeled in the test device than in the prior art discloses the use of high frequency microwave radiation to heat the fuel pellets within the cladding and using the cladding itself as a waveguide. Sensors monitor various operating parameters and a water jacket cools the test cladding.

Abstract: Disclosed is an alpha monitor usable in an automated nuclear fuel pin loading and processing unit. Fuel pins or other elongated pins are fed laterally into the alpha monitor in a singular fashion and are translated by a first roller assembly into a weld flare machining and decontamination substation not forming a part of the invention. Pins return and are lifted upwardly and transferred across to a combined pin lifting and electrode operating means which lifts the pins upwardly into a clamshell electrode assembly which is spread open by a combined pin lifting and electrode operating means. Once inserted the clamshell type electrode arrangement closes around the fuel pins so that inspection can occur. Fuel pins are inspected by charging electrodes to a negative potential and measuring the change in charge occurring when positively charged alpha particles strike the negatively charged electrodes.

Abstract: A method for identifying coated particles having defective coatings desig to retain therewithin a build-up of gaseous materials including:(a) Pulling a vacuum on the particles;(b) Backfilling the particles at atmospheric pressure with a liquid capable of wetting the exterior surface of the coated particles, said liquid being a compound which includes an element having an atomic number higher than the highest atomic number of any element in the composition which forms the exterior surface of the particle coating;(c) Drying the particles; and(d) Radiographing the particles.By television monitoring, examination of the radiographs is substantially enhanced.

Abstract: The counting system includes a portable gamma ray detector having a detecting portion electrically connected to instrumentation for analyzing the radioactivity of nuclear reactor fluids, a radiation shielded panel including a plurality of openings for receiving the detecting portion of the detector, and sample vessels for receiving a radioactive fluid located behind the panel. Samples of radioactive fluids such as reactor coolant, reactor coolant off-gas and containment air, are selectively introduced into the sample vessels. The reactor coolant is cooled, de-pressurized and de-gassed and the off-gas and the liquid are routed to separate sampling vessels. The radioactivity of the radioactive fluid contained in each sample vessel is determined by simply inserting the detecting portion of the detector into a corresponding panel opening. Radiation shielded plugs are inserted into each of unused panel openings to shield the operator against radiation.

Abstract: An apparatus for detecting the location of a failed fuel assembly among a number of in-core fuel assemblies, which utilizes a combination of a tag gas system and a selector valve system. The fuel assemblies are divided into a plurality of groups and all the fuel assemblies in the same group are tagged with the same tag gas. Coolants flowing out from the respective fuel assemblies are individually sampled by sampling pipes and led into intermediate mixers wherein the coolants are mixed. The groups of fuel assemblies are mutually connected via the sampling pipes to the intermediate mixers such that each group of fuel assemblies has the sampling pipes extending therefrom and connected to each of the intermediate mixers. The group to which the failed fuel assembly belongs is identified by the tag gas system, and the selector valve system identifies which mixed coolant from the intermediate mixers contains fission products released from the failed fuel assembly.

Abstract: A double-cylinder selector valve for detecting and locating failed nuclear fuel assemblies including a fixed outer cylinder provided on the circumferential wall surface thereof with a plurality of outer sampling holes arranged in a grid in both the longitudinal and circumferential directions, and a movable inner cylinder disposed rotatably within the fixed outer cylinder and provided on the circumferential wall surface thereof with a plurality of inner sampling holes. Each of coolant sampling pipes extending from the coolant outlets of each of a plurality of nuclear fuel assemblies is connected to one of the outer sampling holes. The inner sampling holes communicate with some of the plurality of outer sampling holes in the fixed outer cylinder at one position of the movable inner cylinder and with others of the outer sampling holes at other positions of the movable inner cylinder.

Abstract: A device is disclosed for applying a head fitted with a measuring instrument to a nuclear fuel bar, the device comprising a casing containing a drilling tip and means for stopping the drilling tip as a bore has been formed through the bar plug and an instrument, such as a pressure gauge for measuring the pressure of the released fission gases, or another instrument adapted to measure a parameter of interest.A method for applying a head containing a measuring instrument to a nuclear fuel bar is also described.

Abstract: Failed fuel detection apparatus for nuclear reactors cooled by liquid metal has a pump (11) for impelling coolant metal along sampling pipes (10) to outlet points (10a) in the pipes. A rotary collector (15) is provided to scan the outlet points with a gap between the outlet points and the collector across which coolant in the sampling pipes can be impelled. The pump (11) is preferably of the helical annular linear induction type with the pipes passing through the annulus of the pump while being wetted internally and externally by liquid metal.

Abstract: A system for detecting grossly failed reactor fuel by detection of particulate matter as accumulated on a filter.

Abstract: A device for collecting fission gas released by a failed fuel rod which device uses a filter to pass coolant but which filter blocks fission gas bubbles which cannot pass through the filter due to the surface tension of the bubble.

Abstract: An electromagnetic pump of the helical annular linear induction type has pumped flow along paths which lie both inside and outside pipes (21) passing through the pump annulus (14). The pipes may be sampling pipes of failed fuel element detection apparatus. A number of pumps according to the invention may be arranged in cascade with selected pipes passing in series through selected combinations of pumps in the cascade so that, with an appropriate energization of selected pumps, flow along one pipe can be created while flow along other pipes is prevented.

Abstract: Device for removing cooling fluid and for locating defective fuel arrays in a nuclear reactor in operation by detection of fission products in the cooling fluid. The device consists of at least two independent locating modules (12, 14) and of sampling pipes (17, 24) associated with each of the arrays and connected to the modules. For each of the arrays of the core, there is at least one adjacent array in contact with the first array via one of its lateral faces, connected by its sampling pipe (24) to a locating module (14) which differs from the module (12) to which the first array is connected by its pipe (17). The device is particularly applicable to fast fission nuclear reactors cooled by liquid sodium.

Abstract: The nuclear reactor container of a boiling water reactor has a dry well and a pressure suppression chamber. The level of the radioactivity in the cooling water filling the pressure suppression chamber is measured by a liquid radiation monitor. An iodine monitor measures a level of the radioactivity of the iodine in the space above the surface of cooling water in the pressure suppression chamber, while a noble gas monitor measures a level of the radioactivity of noble gas in the same space. Outputs from the liquid radiation monitor, the iodine monitor and the noble gas monitor are delivered to an accident judging device which makes judgement as to occurrence of perforation of fuel rods and melt down of fuel rods in the event of a Loss Of Coolant Accident (LOCA), the result of which is displayed at a display device.

Abstract: The invention discloses the use of stable isotopes of neon and argon, that are grouped in preselected different ratios one to the other and are then sealed as tags in different cladded nuclear fuel elements to be used in a liquid metal fast breeder reactor. Failure of the cladding of any fuel element allows fission gases generated in the reaction and these tag isotopes to escape and to combine with the cover gas held in the reactor over the fuel elements. The isotopes specifically are Ne.sup.20, Ne.sup.21 and Ne.sup.22 of neon and Ar.sup.36, Ar.sup.38 and Ar.sup.40 of argon, and the cover gas is helium. Serially connected cryogenically operated charcoal beds are used to clean the cover gas and to separate out the tags. The first or cover gas cleanup bed is held between approximately 0.degree. and -25.degree. C. operable to remove the fission gases from the cover gas and tags and the second or tag recovery system bed is held between approximately -170.degree. and -185.degree. C.

Abstract: An arrangement for crimping a malleable sleeve over a hole in a punctured nuclear fuel rod in order to prevent the escape of fission gases into the external environment. The arrangement operates underwater and includes jaws for crimping the sleeve onto the fuel rod, which are operated by a hydraulic cylinder. The jaws crimp circumferential sealing ridges onto the inner surface of the sleeve, which bear against the fuel rod.

Abstract: A system for sampling material from a remote location which selectively collects a predetermined quantity of material in a valve disposed inside a container. This measured amount of material is transferred to a movable receiving carrier while the receiving carrier is in a sealed relationship with the valve to prevent leakage of the sample material outside the receiving carrier. The movable receiving carrier is transported via an elongated tubular structure to a location remote from the container.

Abstract: A method and an apparatus for detecting failure of nuclear fuel by means of a multi-handle automatic sipper, which comprises a shipper capping operation of mounting a sipper cap of the apparatus for detecting failure of nuclear fuel on the top part of fuel assemblies, an isolation operation of supplying air into the cap after completion of sipper capping operation, thereby forming an air layer, and isolating the fuel assemblies to be detected from other fuel assemblies, a soaking operation of keeping the fuel assemblies in the isolated state for a predetermined period of time, a cell water removal operation of discharging water from system, and a sampling operation of introducing a predetermined amount of cooling water in the fuel assemblies to a sample water receptacle, the operations being provided in sequence, and other operations being carried out in parallel with the aforementioned operations.

Abstract: This invention teaches improved apparatus for the method of detecting a breach in cladded fuel used in a nuclear reactor. The detector apparatus uses a separate bypass loop for conveying part of the reactor coolant away from the core, and at least three separate delayed-neutron detectors mounted proximate this detector loop. The detectors are spaced apart so that the coolant flow time from the core to each detector is different, and these differences are known. The delayed-neutron activity at the detectors is a function of the dealy time after the reaction in the fuel until the coolant carrying the delayed-neutron emitter passes the respective detector. This time delay is broken down into separate components including an isotopic holdup time required for the emitter to move through the fuel from the reaction to the coolant at the breach, and two transit times required for the emitter now in the coolant to flow from the breach to the detector loop and then via the loop to the detector.

Abstract: Nuclear fuel elements or slugs are removed from the nuclear reactor cores and subjected to inspection, according to the invention, by introducing a plurality of such elements into a submerged inspection vessel which is then closed, the liquid driven out by compressed air and deionized water (deionate) circulated through the inspection vessel at a constant rate. A portion of the deionized water is branched from the circulating stream at a constant rate and the activity of at least one fission-product nuclide is determined continuously to plot the activity versus temperature, thereby signaling a possible defect in the shell of a fuel element. In addition, ultrasonic vibration is applied in the inspection vessel to the fuel elements so that deposits on the exterior thereof are released into the deionate whose circulating path includes a filter and an ion-exchange column for removal of such deposits.

Abstract: The present invention relates to a standard fission product emission device, for detecting failed fuel elements in a nuclear reactor of the type cooled by pressurized water, said reactor comprising a pressure-resistant vessel and a core constituted by fuel element assemblies, wherein said device comprises a hollow rod, adapted to be inserted into said vessel and defining a chamber divided into a first chamber and a second chamber located at the end of the rod by a constriction creating a first drop in pressure, said second chamber comprising on its wall a deposit or a metal plate of radioactive material and communicating with the vessel of the reactor, when said device is in position, by a nozzle creating a second drop in pressure greater than the one created by said constriction, a first tube disposed in said rod and opening out at the end of the first chamber remote from the second chamber, said first tube being adapted to be connected to a source of pressurized water at a pressure greater than that of the

Abstract: A sample chamber has the noble gases of effluent first pumped through it from a nuclear process. A quantifying detector of noble gases in the effluent has a predetermined range. A control system is actuated by the detector at the setpoint of a predetermined count rate to terminate the flow of the effluent from the first pump to the sample chamber. A second pump is connected to the chamber to evacuate the chamber upon termination of the first flow into the chamber. A restricted passage is connected between the chamber and the effluent with which to draw the effluent through the chamber by the second pump for so long as the quantity of noble gases in the effluent is above the predetermined setpoint.

Abstract: A failed element detection and location system for use in a nuclear reactor, for example, a liquid metal fast breeder reactor (LMFBR), which utilizes a large number of fuel pins in an active core and which circulates a continuous stream of liquid metal heat exchanging fluid such as liquid sodium past the pins is disclosed herein. This system first collects a combined sample of the fluid just as the latter passes through at least a selected group of containers, each housing a plurality of the fuel pins. This combined sample is detected for the presence or absence of a predetermined contaminant, specifically neutrons, resulting from the failure (break) in one or more of the fuel pins. In the event that the contaminant is detected in the combined sample, individual samples of fluid are collected, one at a time, as the fluid just passes through the selected group of containers.

Abstract: Fuel can failures are located by measuring the age of a faulty fuel element. The method consists in determining the ratio between two fission products constituted by two stable gaseous isotopes of xenon having different kinetics of formation of available gas as a function of the burn-up of the fuel elements.

Abstract: An apparatus for detecting failure of the nuclear fuel rod has an outer cap and 16 (sixteen) inner caps. In checking for any faulty fuel rods, the outer cap is placed to cover the upper ends of 16 (sixteen) fuel assemblies mounted in the reactor core, while the inner caps in the outer cap are disposed on corresponding one of the fuel assemblies. To the outer cap are attached 4 (four) air supplying hoses. The inner caps receive corresponding one of 16 sampling tubes attached to the outer cap, and coolant sampling hoses are connected to the sampling tubes. A bundle member is fixed to the center of the upper surface of the outer cap. The four air supplying hoses and 16 coolant sampling hoses are fixed to the bundle member. The bundle member has a handle attached thereto.