In-vessel automated neutron flux detector system integrated into the control drum assembly

Abstract

A measuring device for determining the power level of the reactor core is provided, which includes an in-vessel detection assembly. The in-vessel detection assembly comprises a rotatable housing that defines a cavity and a detection element positioned at a first angular portion of the cavity within the housing. A control drum for the reactor core and a system for monitoring the reactor power level are also provided.

Description

Technical Field

[0001] Cross - reference to Related Applications This application claims the benefit and priority of U.S. Patent Application No. 18 / 164,964, filed on February 6, 2023, and titled "AUTOMATED IN - VESSEL NEUTRON FLUX DETECTOR SYSTEM EMBEDDED IN CONTROL DRUM ASSEMBLY" under 35 U.S.C. § 120, the content of which is hereby incorporated by reference in its entirety.

[0002] Advanced nuclear reactors with a smaller installation area and a low - power design compared to conventional designs can be transported to remote locations and deployed there for power generation. To operate a nuclear reactor safely, the neutron flux inside the reactor must be accurately and timely monitored to appropriately control the reactor output level. Since the neutron flux inside the reactor is directly proportional to the reactor output, in order to accurately grasp the neutron flux level and the spatial distribution of the neutron flux inside the reactor vessel, advanced nuclear reactors with relatively low power require a highly sensitive neutron flux detection system. Conventional detection devices can be inserted into the fuel assemblies of a nuclear reactor and provide measured values of the neutron flux over a range of output levels. However, incorporating a draw - out assembly into an advanced nuclear reactor would significantly increase the overall size of the reactor and compromise its portability. In the case of fixed detection devices and methods, frequent replacement and / or maintenance is required, which may reduce the operating efficiency of the nuclear reactor. Therefore, there is a need to develop alternative measurement devices and systems to optimize the operating efficiency and safety of advanced nuclear reactors without compromising their portability.

Summary of the Invention

Problems to be Solved by the Invention

[0003] The following summary is provided to facilitate understanding of some of the innovative features inherent in the aspects disclosed herein and is not intended to be a complete description. The various aspects disclosed herein will be fully understood by considering the entire specification, claims, and abstract as a single entity. [Means for solving the problem]

[0004] In various embodiments, measuring devices for determining the power level of a reactor core are disclosed. In some embodiments, the measuring device includes an in-vessel detection assembly. In some embodiments, the in-vessel detection assembly includes a housing defining a cavity inside, and a detection element. In some embodiments, the housing is configured to rotate in a fixed position, the cavity of the housing includes a first angular portion, and the rotation range of the housing includes a number of angular sectors. In some embodiments, the detection element is positioned in the first angular portion of the cavity of the housing and is configured to respond to the neutron flux when the angular displacement of the first angular portion is directed toward the first angular sector of the rotation range of the housing.

[0005] Control drums for reactor cores are disclosed in various embodiments. In some embodiments, the control drum includes a rotatable housing comprising a neutron absorber section and one or more sensing elements configured to respond to a neutron flux. In some embodiments, the rotatable housing is configured to rotate within a range of rotation comprising a number of angular sectors, and the neutron absorber section is located within a first angular portion of the rotatable housing. In some embodiments, one or more sensing elements are housed within the first angular portion of the rotatable housing.

[0006] Systems for monitoring reactor power levels are disclosed in various embodiments. In some embodiments, the system includes a plurality of in-vessel detection assemblies. In some embodiments, each in-vessel detection assembly includes a neutron flux detector that responds to the neutron flux in the source region, the neutron flux in the intermediate region, or a combination thereof, and each in-vessel detection assembly is independently configured to be rotated in a fixed position within a range of rotation by a reactor control drum drive, each range of rotation including a number of angular sectors. In some embodiments, the system is configured to independently determine the rotation of each in-vessel detection assembly based on the neutron flux level in the reactor. In some embodiments, the rotation of an in-vessel detection assembly includes aligning its neutron flux detector with one of the angular sectors of the rotation range of the in-vessel detection assembly.

[0007] These and other purposes, features, and characteristics of this disclosure, as well as the operation and function of the relevant structural elements, and the economics of assembly and manufacture of the parts, will become more apparent by considering the following description and the attached claims (all of which are part of this specification) with reference to the attached drawings. In the various drawings, similar reference numerals refer to the corresponding parts. However, it should be clearly understood that the drawings are for illustrative and explanatory purposes only and are not intended to define any limitations of the embodiments disclosed herein. [Brief explanation of the drawing]

[0008] The various embodiments described herein, along with their purposes and advantages, will be best understood by referring to the following description in conjunction with the accompanying drawings.

[0009] [Figure 1] Figure 1 shows the range of thermal output generated by a nuclear reactor, according to at least one non-limiting aspect of this disclosure.

[0010] [Figure 2]Figure 2 is a cross-sectional view of a reactor vessel according to at least one non-limiting aspect of the present disclosure.

[0011] [Figure 3] Figure 3 is a schematic cross-sectional view of a measuring device according to at least one non-limiting aspect of the present disclosure.

[0012] [Figure 4] Figure 4 is a schematic cross-sectional view of a housing according to at least one non-limiting aspect of the present disclosure.

[0013] [Figure 5] Figure 5 is a schematic view of a rotation range according to at least one non-limiting aspect of the present disclosure.

[0014] [Figure 6] Figure 6 is a perspective view of a control drum according to at least one non-limiting aspect of the present disclosure.

[0015] [Figure 7] Figure 7 is a schematic cross-sectional view of a system for monitoring the output level of a nuclear reactor core according to at least one non-limiting aspect of the present disclosure.

[0016] [Figure 8] Figure 8 is a schematic cross-sectional view of a system for monitoring the output level of a nuclear reactor core according to at least one non-limiting aspect of the present disclosure.

[0017] [Figure 9] Figure 9 is a schematic cross-sectional view of a system for monitoring the output level of a nuclear reactor core according to at least one non-limiting aspect of the present disclosure.

[0018] [Figure 10] Figure 10 is a schematic cross-sectional view of a system for monitoring the output level of a nuclear reactor core according to at least one non-limiting aspect of the present disclosure.

[0019] In the several figures, corresponding reference characters refer to corresponding parts. The illustrations described in this specification exemplify various aspects of the present disclosure in one form, and such illustrations are not to be construed as limiting the scope of the aspects disclosed herein.

Mode for Carrying Out the Invention

[0020] To provide a sufficient understanding of the compositions, functions, manufacturing, use of the compositions, and principles of the methods disclosed herein, specific aspects of the present disclosure are described. Examples of these aspects are shown in the accompanying drawings. Those skilled in the art should understand that the compositions, articles, and methods described particularly herein and illustrated in the accompanying drawings are non-limiting and exemplary examples, and the scope of various examples of the present disclosure is defined only by the claims. Features illustrated or described with respect to one exemplary aspect may be combined with features of other aspects. Such modifications and variations are included within the scope of the present disclosure.

[0021] References herein to "various examples", "some examples", "an example", "one example", etc. mean that the particular features, structures, or characteristics described in relation to the example are included in a certain example. Thus, the expressions "in various examples", "in some examples", "in an example", "in one example", etc. used throughout this specification do not necessarily all refer to the same example. Further, the particular features, structures, or characteristics may be combined in any suitable manner in one or more examples. Accordingly, the particular features, structures, or characteristics illustrated or described with respect to one example may be combined, in whole or in part, without limitation, with the features, structures, or characteristics of one or more other examples. Such modifications and variations are included within the scope of this example.

[0022] In the following explanation, similar reference letters in some drawings refer to the same or corresponding parts. Furthermore, please understand that terms such as "front," "rear," "left," "right," "up," "down," "top," and "bottom" are for convenience only and should not be interpreted as restrictive terms.

[0023] In a nuclear reactor core, fissile fuel such as uranium-235 (sometimes referred to as "235U") interacts with the incident neutron flux to absorb neutrons of appropriate energy, and then fission into numerous light fission products and / or fission fragments, emitting prompt neutrons. These prompt neutrons are then absorbed by other nuclei and spread to other fission events. The lifetime of a prompt neutron is the period from when it is emitted by fission until it is absorbed by another nucleus.

[0024] The average number of neutrons produced in the first fission event that subsequently trigger another fission event is the neutron multiplication factor k. eff It can be quantified by k. Generally, k eff The neutron multiplication factor k is defined as the ratio of the number of neutrons in a given generation to the number of neutrons in the previous generation. eff This is a numerical representation of the reactor's k eff This may indicate the power output generated by the nuclear reactor. eff In a subcritical reactor where k < 1, an auxiliary neutron source is needed to initiate a nuclear fission reaction. In a critical reactor, k eff Since k = 1, neutrons are produced and consumed in a self-replicating chain reaction. eff In a supercritical reactor where the reaction rate is >1, the rate of neutron generation exceeds the rate of neutron consumption. If the reactor state is not adequately controlled, the excess reactivity within the supercritical reactor can rapidly increase in an uncontrollable manner.

[0025] The neutron flux generated within the reactor vessel, including the core assembly, represents the output of the reactor, such as thermal output measured in megawatts (MWt) or electrical output measured in megawatts (MWe). Generally, the region of thermal output generated by a reactor can be divided into various reactivity regions. For example, Figure 1 shows the overall region 10 of thermal output generated by a reactor according to at least one non-limiting aspect of this disclosure. The overall region 10 is divided into a source region flux 12 measured in percent thermal output and counts per second, an intermediate region flux 14 measured in amperes (amps), and a power region flux 16 measured in percent thermal output. Flux regions 12, 14, and 16 are expressed in conventionally used units, respectively. However, the flux values ​​in regions 12 and / or 14 are common to the values ​​in the overall region 10 and are shown vertically aligned in Figure 1.

[0026] In operating nuclear reactors, due to the self-amplification tendency of fissile fuel reactions, the reactor power level may hardly change even when the reactivity state transitions. Therefore, to safely meet power requirements, the reactivity region must be transitioned carefully and cautiously during the startup and / or shutdown procedures. For example, in the startup sequence of a reactor core, the reactivity may be slowly increased in the source region before transitioning to the intermediate region. Generally, to produce a constant power output, the reactor k effThe reactor is maintained in a critical state while in operation. The stability of a nuclear reactor is greatly affected by fluctuations in its operating state, so excessive changes such as moving the reactor into and / or out of the power range can cause unexpected secondary effects, such as a sudden transition from a subcritical to a supercritical state, potentially destabilizing and / or causing the reactor to run out of control, making it extremely difficult to return to a normal state. Furthermore, in the reactor core, a considerable amount of heat can continue to be generated even after shutdown due to the production of delayed neutrons, and in this case, if the reactivity is not properly monitored in a dormant reactor, the reactivity may increase unexpectedly. Therefore, it is usually necessary to accurately monitor the output of a nuclear reactor regardless of its operating state.

[0027] Reactivity control systems reduce and / or slow down neutron production by moving neutron-absorbing elements into the reactor core. For example, in conventional pressurized water reactors (PWRs), long, retractable control rods made of flammable absorbent material are inserted through the vessel wall into the fuel assembly in the core to reduce reactivity. To adjust the neutron-absorbing elements in a timely and accurate manner, reactivity control systems rely on feedback from nuclear instruments such as an out-of-core detection assembly consisting of a source-region detector, an intermediate-region detector, and / or a power-region detector, and / or an in-core detection assembly consisting of a source-region detector and / or an intermediate-region detector.

[0028] Many neutron detectors are constructed from materials with a neutron cross-section large enough to absorb and / or interact with the incident neutron flux, indirectly producing a measurable flux of charged particles and / or currents. This measurable flux is then used by the accompanying hardware to generate an observable response signal. Generally, the ability of a neutron detector to make accurate measurements is limited by its measurement sensitivity. For example, neutron detectors for measuring source-region flux and / or intermediate-region flux are typically constructed from materials with a higher neutron cross-section, i.e., higher measurement sensitivity, than power-region detectors. Therefore, the response signals produced by source-region detectors, intermediate-region detectors, and / or in-core detection assemblies may saturate when exposed to neutron fluxes larger than originally designed. Similarly, power-region detectors may not have the sensitivity necessary to respond to low-region fluxes.

[0029] Conventional in-core detection assemblies, comprising source region detectors and / or intermediate region detectors, are axially inserted into the reactor core through penetrations located at the top and / or bottom of the reactor vessel, providing measurements and / or spatial distributions of the source and / or intermediate regions within the core in both shutdown and startup conditions. However, their highly sensitive detector configurations are prone to sensitivity degradation when exposed to power region fluxes. Therefore, conventional in-core detection assemblies are withdrawn at high power levels and stored in a low-radiation field outside the core to maintain their service life.

[0030] In contrast, extracore detection assemblies are fixed outside the reactor vessel, around the core, and detect leaked neutrons that can indicate the overall reactor output. Therefore, while extracore detection assemblies have the advantage of being easy to maintain and install thanks to their location, they may lack the signal resolution of in-core detection assemblies necessary for accurately assessing the spatial power distribution. Consequently, reactivity control systems typically require one or more neutron detectors to reliably control reactor output.

[0031] As a solution to provide reliable off-grid power, advanced reactor designs are emerging that employ structures smaller in both size and power than conventional PWRs, such as microreactors. For example, the eVinci® microreactor currently under development by Westinghouse consists of a microreactor vessel integrated into a dedicated container as a single package. The space between the microreactor vessel and the container is minimized to create an assembled package with an occupied area optimized for truck transport to its final destination. A cross-sectional perspective view of a microreactor vessel 100 according to at least one non-limiting aspect of this disclosure is shown in Figure 2. The reactor vessel 100 includes a radial reflector 110, a central core 120 including a fuel assembly, and a non-instrumented control drum 130. The radial reflector 110 maximizes neutron efficiency within the vessel 100 by preventing leaked neutrons from being emitted through the vessel 100. A motion control system is also included to rotate the non-instrumented control drum 130. Thus, the micro reactor vessel 100 maintains a space-saving shape while maximizing its potential power output. Other exemplary micro reactors and their operating methods are described in detail in U.S. Patent Application No. 17 / 084,365 and U.S. Patent Application No. 18 / 057,208, each of which is owned by the applicant of this disclosure and is incorporated herein by reference in its entirety.

[0032] Due to spatial constraints between the reactor vessel and the container, effectively managing excessive reactivity and spatial neutron flux distribution within a micro-reactor can be difficult. For example, conventional extracore equipment and control ("I&C") systems, which are solely for the axial movement of a conventional movable in-core detection assembly, can occupy a considerable amount of space from the vessel surface. Therefore, implementing a conventional movable in-core detection assembly in a micro-reactor can significantly increase the overall footprint of the container, potentially compromising the portability of the micro-reactor. Furthermore, to avoid a decrease in detector sensitivity, the conventional in-core detection assembly must be completely withdrawn from the micro-reactor vessel 100 during power operation, which increases the space requirements for the designated micro-reactor installation area.

[0033] In an attempt to circumvent the problems associated with conventional mobile in-core detection assemblies, fixed in-core detection assemblies have been developed that are less susceptible to degradation of sensitivity when exposed to power-region neutron flux, in order to provide accurate measurements during the startup and / or shutdown sequences. However, the material properties of these fixed in-core detection assemblies change irreversibly over time in neutron-rich environments. Furthermore, in the long term, fixed in-core detection assemblies may experience a decrease in sensitivity, for example, before the planned lifespan of the fuel assembly of 8 years has elapsed. Therefore, fixed in-core detection assemblies require frequent calibration, inspection, and / or replacement over the planned lifespan of the microreactor's fuel assembly in order to maintain measurement accuracy in the source region, thus complicating the operation of the microreactor.

[0034] Furthermore, the radial reflector 110 intentionally reduces the neutron field intensity surrounding the vessel 100 to a low level during power operation. Therefore, it would be practically impossible for conventional out-of-core detection assemblies to detect the neutron flux generated within the vessel 100 during startup and / or shutdown, when the neutron field intensity surrounding the vessel 100 is orders of magnitude lower than during power operation, regardless of their measurement sensitivity.

[0035] While microreactors packaged in transportable containers offer advantages over conventional reactor designs, such as smaller size, greater portability, and / or higher neutron efficiency, it can be challenging to implement instruments and devices for managing reactivity within the microreactor without increasing the overall size of the container, compromising flux measurement accuracy, and / or reducing the operating efficiency of the microreactor. Accordingly, various aspects of this disclosure provide, for example, various methods and devices for measuring neutron flux in various regions within the core of a microreactor and maintaining high measurement accuracy and / or operating efficiency over the planned lifespan of the fuel assembly.

[0036] Referring here to Figure 3, a schematic cross-sectional view of a measuring device 1000 for determining the power level of a reactor core is shown according to at least one non-limiting aspect of the present disclosure. The measuring device 1000 includes an in-vessel sensing assembly 1100 comprising a sensing element 1110 and a housing 1120. In various examples, the sensing element 1110 is configured to respond to the incident neutron flux in the source region and / or intermediate region. In some examples, the sensing element 1110 is made of a material having a thermal neutron cross-section of greater than 1 barn, greater than about 5 barns, greater than about 10 barns, greater than about 25 barns, greater than about 50 barns, greater than about 75 barns, greater than about 100 barns, or about 1000 barns. In certain examples, the detection element 1110 may include a 235U fission chamber, a boron trifluoride (BF3) ratio counter, a boron-reinforced compensated ion chamber, an uncompensated ion chamber, a vanadium and / or rhodium automated neutron detector (SPND), a solid-state neutron detector, or a combination thereof. Other configurations are also possible in this disclosure. For example, in some embodiments, the detection element 1110 may be configured to interact indirectly and / or directly with gamma rays, epithermal neutrons, and / or fast neutrons.

[0037] Figure 4 shows a schematic cross-sectional view of the housing 1120 according to at least one non-limiting aspect of the present disclosure. In various examples, the outer surface of the in-vessel detection assembly 1100 is defined by the outer wall 1122 of the housing 1120, the outer wall 1122 defining a cavity inside it. The in-vessel detection assembly 1100 is configured to fit within the cavity of a radial reflector. For example, the outer wall 1122 of the housing 1120 may be cylindrical in shape with an outer diameter slightly smaller than the diameter of the cavity of the control drum. In some examples, the housing 1120 has an outer diameter approximately the same as the control drum of the microreactor. In some examples, the housing 1120 may have a length approximately the same as the length of the cavity of the control drum. Thus, the housing 1120 may be configured to be incorporated into a microreactor vessel and / or to replace a control drum in a reactor vessel. Other configurations of the housing 1120 are also possible in the present disclosure. For example, the housing 1120 may be configured to have a hexagonal, elliptical, or lobe-shaped cross-section that fits within a circular cross-sectional shape having an outer diameter slightly smaller than the diameter of the control drum cavity, and / or a module sub-length section having a length approximately the same as the length of the module unit cell and / or reflector section of the 200MWth module reactor vessel.

[0038] Referring further to Figure 4, the cross-sectional shape of the cavity defined by the outer wall 1122 may be divided radially into two or more nested concentric radial sectors 1123. For example, if the outer wall 1122 is cylindrical, the cross-sectional shape of the cavity defined inside it may be divided radially into a radially inner sector 1123a, which is a circular region having a smaller diameter than the outer wall 1122, and a radially outer annular sector 1123b that surrounds the radially inner sector. In some examples, the cavity includes one or more radial sectors sandwiched between the radially inner sector and the radially outer sector.

[0039] Furthermore, the cross-sectional shape of the cavity defined by the outer wall 1122 is divided into two or more angular sections. For example, in the cross-sectional shape of the cylindrical outer wall 1122, the angular section 1124 is defined as the region where a circular segment defined by the central angle 1125 overlaps with one or more radial sectors 1123. A circular segment that overlaps only with the radially outer sector 1123b becomes an angular section having both a radially inner surface and a radially outer surface. In contrast, a circular segment that overlaps with the region including the radially inner sector 1123b becomes an angular section having an inner point at the center of the cavity. Since the relative positions of the angular sections 1124 relative to each other and to the housing 1120 are fixed, when the housing 1120 rotates, all the angular sections also rotate accordingly around the center of the housing 1120.

[0040] In various examples, the cavity includes a first angular portion 1124a defined by a first central angle 1125a and having a radially outer surface and a radially inner surface tangent to the outer periphery of the cavity cross-section. In some examples, the cavity includes a second angular portion 1124b defined by a second central angle 1125b that is greater than the first central angle 1124a. In certain examples, the central angle 1125a is less than 180°, less than 120°, about 90°, or about 60°. Other configurations are also possible in this disclosure. For example, in some embodiments, the cavity may be divided into quarters, sextents, octents, or any other number of angular portions of the same size, their radial portions, and / or combinations thereof.

[0041] It should be understood that the terms “radial” and “angle” as used in this disclosure with respect to the cross-sectional shape of the cavity defined by the housing refer, respectively, to any direction extending from the center of the housing in the axial plane defining the cross-section and any angle in that plane with the center of the housing as the vertex. Accordingly, the use of the terms “radial” and “angle” is not limited to circular or circular configurations, and should not be interpreted as meaning that the radial sector 1123 and angle portion 1124 in Figure 4 are limited to circular or circular configurations. For example, non-limiting embodiments of this disclosure are also possible in which the radial sector 1123 and / or angle portion 1124 include polygonal configurations. Accordingly, in such embodiments, the cavity of the housing 1120 may include heterogeneous shapes including a polygonal radial inner sector and / or radial outer sector, its angle portion, or any combination of these with a circular radial sector. Furthermore, while the radial sectors 1123 and / or angular portions 1124 described above indicate spatial relationships within a single cavity, other configurations of the housing 1120 conceivable in this disclosure may define subcavities that are physically separated within the housing. Thus, in some embodiments, the cavity of the housing 1120 may be divided into subcavities having structural members arranged according to the radial sectors 1123 and / or angular portions 1124 described above.

[0042] For the purpose of explaining the orientation of the angle portion 1124 relative to the radiation source, the angular alignment with the radiation source is based on half of the central angle 1125 of the angle portion. For example, as shown in Figure 4, the angle portion 1124 is angularly aligned with the neutron source when the midpoint of the radial outer surface of the angle portion 1124 (corresponding to half of the central angle) directly faces the incident neutron flux 500 from the neutron source.

[0043] In addition to the above, the housing 1120 is configured to be rotatable in a fixed position. For example, the ends of the housing 1120 may be configured to receive torque via a drive shaft or transmission output of a drive unit. As used herein, the expression “rotatable in a fixed position” refers to angular motion without translational and / or linear motion. Thus, the housing 1120 having this configuration is rotatable within the cavity without being dislodged from the cavity. In some examples, the housing 1120 includes an axial shaft coupler configured to work in conjunction with existing control drum drive hardware of the reactivity control system. The housing 1120 having this configuration may be driven by an existing control drum drive unit and / or motion control system once inserted into the cavity of the control drum. Thus, in some embodiments, the in-vessel detection assembly 1100 may be configured to be mounted on a control drum-based reactivity control system without requiring a dedicated I&C system.

[0044] Referring here to Figure 5, a schematic diagram of the rotation range 1102 of the housing 1120 according to at least one non-limiting aspect of the present disclosure is shown. The rotation range 1102 consists of a number of angular sectors 1104, each defined by a single central angle 1105, the sum of which represents the total angle swept by the entire rotation range of the housing 1120. In various examples, the rotation range 1102 includes a first angular sector 1104a. In some examples, the rotation range 1102 may have a span of about 180° or more, starting from the first angular sector 1104a. It may also have two or more angular sectors 1104 of equal size. In some examples, the first central angle 1105a is about 30°, about 45°, about 60°, about 90°, or about 120°. In some examples, each of the angular sectors 1104 is of equal size.

[0045] For the purpose of describing the orientation of the angular sector 1104 with respect to the radiation source, the angular alignment with the radiation source is based on half of the central angle 1105 of the sector. However, in contrast to the radial sector 1123 and angular portion 1124 described above, the rotational range 1102 and angular sector 1104 should not be interpreted as structural characteristics. Rather, the rotational range 1102 defines paths and / or numerous stationary regions that the housing 1120 or regions defined within the housing can traverse when the housing 1120 rotates. For example, as shown in Figure 5, if the first angular sector 1104a is aligned with the incident neutron flux 500, the first angular portion 1124a may be moved to a first position aligned with the first angular sector 1104a as the housing 1120 rotates appropriately. Subsequently, when the housing 1120 rotates 180° to the second angular sector 1104b, the first angular portion 1124a will be the largest deviation from the first angular sector 1104a that matches the incident neutron flux. Thus, the rotation range 1102 and the angular sector 1104 may be used as a reference to indicate the degree and / or state of rotation of the housing, and by extension, the orientation of the housing 1120 with respect to the neutron source and the inference of its orientation. Accordingly, in some embodiments, the rotation range 1102 may be configured to provide a reference point and / or set point for rotating the housing 1120 in the I&C system.

[0046] Referring here to Figures 3 and 4, the housing 1120 may be configured to interact with the incident neutron flux. For example, a portion of the housing 1120 may include a neutron absorber 1130 made of a material having high neutron absorption and / or neutron scattering cross-section. The length of the neutron absorber 1130 is configured to be approximately the same as that of the housing 1120. In various examples, the neutron absorber 1130 includes a radial outer surface 1132 and a radial inner surface 1134. In some examples, the neutron absorber 1130 is made of boron, gadolinium, beryllium oxide, graphite, or a combination thereof. In some examples, the neutron absorber 1130 comprises multiple layers. In one example, the neutron absorber comprises multiple layers. A neutron absorber 1130 having this configuration can absorb the incident neutron flux.

[0047] The neutron absorber 1130 is located within the cavity of the housing 1120. For example, the neutron absorber 1130 may be located within the first angled portion 1124a. In some examples, the neutron absorber 1130 is in direct contact with the outer wall 1122 of the housing 1120. In some examples, the neutron absorber 1130 comprises the entire region defined by the first angled portion 1124a.

[0048] When the radial outer surface 1132 of the neutron absorber 1130 is in a position where it is directly visible from the neutron source, the neutron absorber 1130 can absorb and / or dissipate the incident neutron flux from the neutron source, thereby suppressing further propagation of the neutron flux. Thus, when the in-vessel detection assembly 1100 is inserted into an existing reactor vessel, the first angle section 1124a and the neutron absorber 1130 within the first angle section 1124a can match the incident neutron flux from the fuel assembly, thereby preventing interaction between the neutron flux and surrounding structures such as the radial reflector assembly of the reactor vessel, and thereby reducing the reactivity within the reactor core. Furthermore, by rotating the housing 1120 so that the radial inner surface 1134 of the neutron absorber is exposed to the neutron source, a portion of the neutron flux generated by the neutron source can be reflected back toward the neutron source, and the remaining neutron flux will collide with and be absorbed by the radial inner surface 1134, thereby preventing the neutron flux from further propagating to the radial outer surface 1132 and / or its surrounding region. Therefore, the first angled portion 1124a may be rotated so as not to align with the neutron source in order to minimize the influence of the neutron absorber 1130 on the surrounding neutron population and / or to shield the region in contact with the radial outer surface 1132.

[0049] Referring to Figures 3 and 4, the detection element 1110 is mounted on the housing 1120. For example, the detection element 1110 may be mounted on a portion of the housing 1120 defined by an angled portion 1124. In various examples, the detection element 1110 is located within the first angled portion 1124a. In some examples, the detection element 1110 is flush with the outer surface of the housing 1120 and / or embedded slightly below the outer surface of the housing 1120. Thus, by rotating the housing 1120, the distance and / or position of the detection element 1110 with respect to a reference point outside the housing 1120 can be controlled. Furthermore, the detection element 1110 may be positioned along the length of the housing 1120, if desired. For example, the axial position of the detection element 1110 may be such that it matches the neutron flux expected when the in-vessel detection assembly 1100 is inserted into the cavity of the radial reflector. Other configurations are also possible in this disclosure. For example, in another embodiment, the in-vessel detection assembly 1100 may comprise a plurality of detection elements arranged at various axial and / or angular positions and / or independently configured to respond to the neutron flux in the source region and / or the neutron flux in the intermediate region.

[0050] In examples where the neutron absorber 1130 is positioned in the first angular section 1124a, the detection element 1110 may be mounted on the neutron absorber 1130. For example, the detection element 1110 may be flush with the radial outermost surface of the first angular section 1124a and / or the radial outer surface 1132 of the neutron absorber 1130, and / or embedded immediately inside it. In some examples, the detection element 1110 is embedded in a recess extending radially inward from the outer wall 1122 of the housing 1120 toward and / or into the radial outer surface 1132 of the neutron absorber 1130. The detection element 1110 having this configuration is conditionally capable of interacting with the incident neutron flux. For example, when the housing 1120 is rotated so that the first angled section 1124a and the detection element 1110 within the first angled section 1124a are aligned with the neutron source, the incident neutron flux from the neutron source can interact with and / or collide with the detection element 1110 without having to overcome a large obstacle. When the housing 1120 is rotated sufficiently so that the first angled section 1124a is away from the neutron source, the radial inner surface 1134 of the neutron absorber 1130 becomes directly visible to the neutron source, preventing and / or suppressing the incident neutron flux from the neutron source from further propagating toward the radial outer surface 1132 and / or the detection element 1110. Accordingly, the in-vessel detection assembly 1100 may be configured to conditionally allow and / or block interaction between the detection element 1110 and the incident neutron flux based on the rotational state of the housing 1120 within the reactor vessel and / or the position of the detection element 1110, which may be provided by existing equipment and control systems for the control drum. Thus, in some embodiments, the in-vessel detection assembly 1100 may be configured to provide multiple operating modes independently of axial position without requiring a dedicated control system and / or mechanism when inserted into the vessel of the reactor core, thereby avoiding operational and / or transportation problems associated with conventional pull-out detection assemblies.

[0051] Furthermore, the neutron absorber 1130 may have a maximum thickness of at least 500 microns, at least 1 millimeter, at least 1 centimeter, or about 5 centimeters. In some examples, the neutron absorber 1130 has a uniform thickness. In certain examples, the neutron absorber 1130 may extend over the entire axial length of the housing 1120. Other configurations are also possible in this disclosure. For example, in some embodiments, the thickness of the neutron absorber 1130 may vary and / or decrease symmetrically toward the edges of the neutron absorber.

[0052] The thickness and / or composition of the portion of the neutron absorber 1130 that supports the detection element 1110 (defined as the radial distance between the detection element 1110 and the radial inner surface 1134) may be configured to maximize the neutron shielding effect on the detection element 1110 and / or minimize the reduction in sensitivity of the detection element 110 when appropriately oriented with respect to the neutron source as described above. For example, the ratio of the thickness of the portion of the neutron absorber 1130 that radially supports the detection element 1110 to the thickness of the detection element 1110 may be greater than approximately 20:1, approximately 15:1, approximately 10:1, approximately 9:1, approximately 8:1, approximately 7:1, approximately 6:1, approximately 5:1, approximately 4:1, approximately 3:1, approximately 2:1, or approximately 1:1. In some examples, the portion of the neutron absorber 1130 supporting the detection element 1110 is made of a material having an average thermal neutron cross-section of at least 10 burners, at least 15 burners, at least 20 burners, at least 30 burners, at least 50 burners, at least 100 burners, at least 500 burners, approximately 1000 burners, or approximately 100,000 burners. In certain examples, the neutron absorber 1130 may comprise one or more layers of boron-10 based material and / or gadolinium-157 based material. The neutron absorber 1130 having this configuration can protect the detection element 1110 from unnecessary exposure to high-power neutron fluxes (e.g., neutrons in the power region of a 3 MWe and / or 15 MWt reactor operating at full power up to 120% or a small modular reactor with power up to 200 MWt) for more than eight years, thereby reducing the frequency of calibration, inspection, and / or replacement of the detection element 1110 due to excessive exposure of the detection element to high-power neutron radiation. Accordingly, in some embodiments, the in-vessel detection assembly 1100 may be configured to remain in a static standby state to protect the detection element 1110 within the reactor vessel at high power over the planned service life of the nuclear fuel assembly, thereby facilitating low-power measurements necessary for safely controlling the core as the reactor transitions to startup and / or shutdown states, while maintaining the measurement sensitivity of the detection element 1110 in the source region and / or intermediate region.Therefore, the in-vessel detection assembly 1100 may be configured to extend the service life of the detection element 1110, thereby providing advantages such as safety, reliability, and / or operating efficiency when the measuring device 1000 is implemented in a reactor such as a micro reactor.

[0053] Figure 6 shows a perspective view of a control drum 2100 for a reactor core according to at least one non-limiting aspect of the present disclosure. The control drum 2100 includes a rotatable housing 2120 comprising a neutron absorber section 2130 and one or more sensing elements 2110 configured to respond to a neutron flux. The rotatable housing 2120 and each sensing element 2110 of the control drum 2100 are similar in many respects to other housings and sensing elements described elsewhere in the present disclosure (these descriptions are not repeated here for the sake of brevity). In various examples, the rotatable housing 2120 is configured to have a cylindrical cross-sectional shape comprising two or more angular sections and a radially outer sector, each defined by a single central angle. The radially outer surface of the neutron absorber section faces away from the radial center of the rotatable housing, and the radially inner surface faces inward. In some examples, the control drum includes multiple sensing elements.

[0054] The rotatable housing 2120 and the neutron absorber section 2130 may be configured similarly to the housing 1120 and neutron absorber 1130 described above. Thus, the rotatable housing 2120 may be configured to rotate over a range of rotation defined by a number of angular sectors while remaining within the cavity of the control drum. The neutron absorber section 2130 may be located within a first angular portion of the rotatable housing, which has a region of circular sectors overlapping radially outer sectors. The first angular portion of the rotatable housing is configured to house one or more detection elements.

[0055] Furthermore, the rotatable housing 2120 may be configured to be mounted in the cavity of an existing control drum of the microreactor and may be configured to be driven by the microreactor's control drum motion control system. Additionally, the neutron absorber section 2130 may be configured to absorb a significant amount of power-region neutrons generated by the microreactor's fuel assembly. For example, the neutron absorber section 2130 may be made of a material with a high neutron cross-section, such as a boron-10-based material, and may have a thickness of at least 1 millimeter. In some examples, the neutron absorber section 2130 includes a first angular section having a central angle of about 120° or less, about 90° or less, or about 60°. The rotatable housing 2120 having this configuration may be positioned along the outer circumference of the microreactor vessel and rotated by an existing drive system for the control drum so that the radial outer surface of the first angular section and / or the neutron absorber section aligns with the central fuel assembly of the microreactor core, thereby absorbing a significant amount of power-region neutrons. Subsequently, by rotating the rotatable housing so that the radial outer surface of the neutron absorber section faces the outer periphery of the reactor vessel, furthest from the central fuel assembly, less interaction with neutrons occurs, and therefore the reactivity within the core does not decrease significantly.

[0056] Each of the one or more detection elements 2110 may be configured similarly to the detection element 1110 described above. Thus, each of the one or more detection elements 2110 may be configured to respond to the neutron flux in the source region and / or the neutron flux in the intermediate region. In some examples, each of the one or more detection elements 2110 may be mounted on the neutron absorber section 2130 and / or distributed along the length of the neutron absorber section 2130. Thus, each of the one or more detection elements 2110 may be configured to measure the axial power distribution in the core and / or vessel of a running or shut-down microreactor when the first angular portion of the rotatable housing 2120 is in a first position facing the central fuel assembly.

[0057] Furthermore, each of the one or more detection elements 2110 may be embedded flush with the interior of the outer surface of the neutron absorber section 2130 so as not to hinder the rotation of the rotatable housing 2120 within the cavity of the control drum. Thus, the rotatable housing 2120 can be easily rotated to and / or from a second position, in which the detection elements 2110 are oriented away from the central fuel assembly, and the radial inner surface of the neutron absorber section 2130 can prevent the power-region neutron flux from being transmitted from the central fuel assembly to the detection elements 2110. In some embodiments, a control drum 2100 having this configuration can, in a first mode, reduce the reactivity of the core to expose the detection elements to free neutrons, and in a second mode, protect the detection elements from severe high-power conditions without substantially reducing the reactivity of the core. Thus, in some embodiments, the control drum 2100 may be configured to maintain the source-region and / or intermediate-region measurement sensitivity of the detection element 2110 during high-power reactor operation conditions while controlling the reactivity of the micro-reactor core over the planned service life of the nuclear fuel assembly in the core, thereby enabling reliable low-power measurements necessary for safely controlling the micro-reactor core during startup and / or shutdown transitions without significantly redesigning existing equipment and control systems for the control drum.

[0058] Referring now to Figure 7, a cross-sectional view of a system 3000 for monitoring the power level of the core 4100 of a reactor vessel 4000 according to at least one non-limiting aspect of the present disclosure. In various examples, the system 3000 includes a plurality of in-vessel detection assemblies 3100. The plurality of in-vessel detection assemblies 3100 are inserted into the cavity 4112 of a neutron reflector assembly 4110 configured to surround the central fuel assembly 4120. In some examples, the system 3000 may include a plurality of out-of-core detection assemblies 3200. In certain examples, the reactor vessel 4000 is a micro-reactor vessel.

[0059] Each of the in-vessel detection assemblies 3100 is similar in many respects to other in-vessel detection assemblies described elsewhere in this disclosure, and for brevity, the descriptions of these in-vessel detection assemblies will not be repeated. In various examples, each of the detection assemblies 3100 includes a neutron flux detector 3110, which is independently configured to rotate in a fixed position within a rotation range. Each neutron flux detector 3110 may be configured similarly to the detection element 1110 described above. Thus, each neutron flux detector 3110 may be configured to respond to the neutron flux in the source region, the neutron flux in the intermediate region, or a combination thereof. In some examples, the system 3000 includes at least one in-vessel detection assembly 3100a having a neutron flux detector for the source region, and at least one in-vessel detection assembly 3100b having a neutron flux detector for the intermediate region. Furthermore, the system 3000 may include a plurality of out-of-core detection assemblies 3200. Each of the out-of-core detection assemblies is configured to respond to the flux in the upper intermediate region and / or the flux in the power region and is located outside the reactor vessel 4000. In a particular example, the system 3000 includes at least three in-core detection assemblies 3100a, at least three in-core detection assemblies 3100b, at least three out-of-core detection assemblies 3200a configured to detect the neutron flux in the upper intermediate region, and at least three out-of-core detection assemblies 3200b for detecting the neutron flux in the power region. A system 3000 having this configuration can provide accurate measurements at all power levels and in the overlapping region between them. Thus, in some embodiments, the system 3000 is configured to measure the reactivity of the core from complete shutdown up to 100% reactor power, up to 120% reactor power, or up to accident state power levels.

[0060] Each of the in-vessel detection assemblies 3100 may be configured similarly to the in-vessel detection assemblies 1100 and / or control drums 2100 described above. In various examples, each of the in-vessel detection assemblies 3100 is configured to rotate independently in a fixed position within a rotation range, each rotation range being defined by a number of angular sectors. Furthermore, the first angular sector of each rotation range is oriented toward the incident neutron flux from the reactor core. In some examples, each of the in-vessel detection assemblies 3100 includes a neutron absorber 3130. Each of the neutron flux detection units 3110 may be embedded in the radially outer surface of the neutron absorber 3130. In certain examples, each of the neutron absorbers 3130 is configured to have a neutron cross-section similar to that of a non-instrumented control drum. Thus, in some embodiments, each of the in-vessel detection assemblies 3100 may be configured as an instrumented control drum. Therefore, each in-vessel detection assembly 3100 having this configuration can replace an existing non-instrumented control drum in a micro-reactor to reliably measure the neutron flux in the source region and / or the intermediate region while maintaining the neutron absorption capacity of the non-instrumented control drum.

[0061] To enable reliable measurements during control sequences without compromising control responsiveness or requiring a dedicated I&C system, the system 3000 described above may be integrated into an existing core reactivity control system, including a non-instrumented control drum 4130. For example, Figures 7 to 10 show various operating modes of the system 3000 according to at least one non-limiting aspect of the present disclosure. When the reactor 4000 is shut down, reactivity must be kept to a minimum by orienting the available neutron absorbers 3130 inward toward the central fuel assembly 4120, as shown in Figure 7, for example, thereby maintaining a subcritical reactor state.

[0062] Figure 8 shows the source region startup state of system 3000. As the non-instrumented control drum 4130 begins to rotate away from the central fuel assembly 4120, the reactivity of the core 4100 increases, supplying the core with neutron flux from the source region. The in-vessel detection assembly 3100a remains facing inward to obtain the measurement sensitivity necessary to reliably detect neutrons from the source region. During low-power startup, the intermediate-level in-vessel detection assembly 3100b also faces inward, but its neutron detection section does not have neutron sensitivity to neutrons from the source region and therefore does not substantially contribute to neutron measurement.

[0063] Figure 9 shows the intermediate region activation state of system 3000. As the non-instrumented control drum 4130 continues to rotate away from the central fuel assembly 4120, the reactivity of the core 4100 increases from the source region activation state to the intermediate region power level. The in-vessel detection assembly 3100a for the source region rotates away from the central fuel assembly 4120, protecting the vulnerable neutron detector from damage by intermediate region neutrons. The in-vessel detection assembly 3100b for the intermediate region remains facing inward to obtain the measurement sensitivity necessary to reliably detect intermediate region neutrons. Furthermore, the out-of-core assembly 3200a begins to detect intermediate neutrons.

[0064] Figure 10 shows the reactor core 4100 at full power. All neutron measurements at full power are performed by the out-of-core assembly 3200. The in-core detection assembly 3100 and the non-instrumented control drum 4130 are all facing outwards, minimizing neutron absorption, which allows the central fuel assembly 4120 to supply neutrons in the power range. Furthermore, the in-vessel detection assembly 3100 in this orientation is protected from the harsh power range neutrons, so it maintains measurement sensitivity even while inside the reactor core 4100, and can reliably perform measurements when the power must then begin to decrease. In addition, since the temperature inside the reactor vessel 4000 decreases with distance from the central fuel assembly 4120, at full power, the neutron detectors of the in-core detection assemblies 3100a and 3100b are each located in the coldest region of the reactor vessel 4000. Accordingly, in some embodiments, the system 3000 may be configured to protect the neutron detector of the in-core detection assembly from exposure to high-temperature and power-range neutrons, thereby providing the advantage of extending the service life of the in-core detection assembly 3100.

[0065] Various aspects of this disclosure include, but are not limited to, those listed in the following numbered sections.

[0066] Item 1 - Measuring device for determining the power level of a reactor core. The measuring device comprises an in-vessel detection assembly. The in-vessel detection assembly comprises a housing that defines a cavity, the housing is configured to rotate in a fixed position, the cavity of the housing comprises a first angular portion, and the rotation range of the housing comprises a number of angular sectors. The in-vessel detection assembly further comprises a detection element located in the first angular portion of the cavity of the housing, the detection element is configured to respond to the neutron flux when the angular displacement of the first angular portion is directed toward the first angular sector of the rotation range.

[0067] Item 2 - The measuring device according to Item 1, wherein the in-vessel detection assembly is configured to remain within the reactor core cavity for the planned lifetime of the reactor core fuel assembly.

[0068] Item 3 - A reactor is a micro reactor, and the measuring device is as described in any one of items 1 or 2.

[0069] Item 4 - An in-vessel detection assembly is a measuring device according to any one of items 1 to 3, configured to remain in the reactor core cavity for approximately 8 years or more.

[0070] Item 5 - A measuring device according to any one of items 1 to 4, wherein the rotation range of the housing is approximately 180 degrees or more.

[0071] Item 6 - The measuring device according to any one of items 1 to 5, wherein the detection element is embedded in the housing.

[0072] Item 7 - The measuring apparatus according to any one of items 1 to 6, wherein the housing comprises a neutron absorber, the neutron absorber being located within a first angular portion of the housing.

[0073] Item 8 - The measuring apparatus according to Item 7, wherein the detection element is attached to a neutron absorber.

[0074] Item 9 - The measuring device according to any one of items 7 to 8, wherein the detection element is embedded in the radially outermost part of the neutron absorber.

[0075] Item 10 - The measuring apparatus according to any one of items 1 to 9, wherein the detection element is configured to respond to the neutron flux in the source region, the neutron flux in the intermediate region, or a combination thereof.

[0076] Item 11 - The measuring apparatus according to any one of items 1 to 10, wherein the in-vessel detection assembly is configured to protect the detection element from neutron flux when the housing is rotated such that a first angular portion of the cavity of the housing aligns with a second angular sector of the rotation range.

[0077] Item 12 - The measuring device according to any one of items 1 to 11, wherein the housing is configured to be rotated by a drive for the control drum of a nuclear reactor.

[0078] Section 13 - Control drum of a reactor core. The control drum comprises a rotatable housing having a neutron absorber section and one or more sensing elements configured to respond to a neutron flux. The rotatable housing is configured to rotate within a range of rotation consisting of a number of angular sectors, and the neutron absorber section is located within a first angular sector of the rotatable housing. One or more sensing elements are housed within the first angular sector of the rotatable housing.

[0079] Item 14-1 or more detection elements are mounted on a neutron absorber section, as described in Item 13.

[0080] Item 5 - The control drum according to any one of items 13 to 14, comprising a plurality of detection elements distributed axially along the length of the neutron absorber section.

[0081] Item 16- A control drum according to any one of items 13 to 15, wherein one or more detection elements are embedded in the outer surface of the neutron absorber section.

[0082] Item 17- The control drum according to item 16, wherein one or more detection elements are flush with the outer surface of the neutron absorber section.

[0083] Section 18 - A system for monitoring the power level of a nuclear reactor, comprising a plurality of in-vessel detection assemblies. Each in-vessel detection assembly comprises a neutron flux detector that responds to the neutron flux of the source region, the neutron flux of the intermediate region, or a combination thereof. Each in-vessel detection assembly is independently configured to rotate in a fixed position over a rotation range by a reactor control drum drive, each rotation range comprising a number of angular sectors. The system is configured to independently determine the rotation of each in-vessel detection assembly based on the neutron flux level in the reactor, the rotation of an in-vessel detection assembly comprising aligning its neutron flux detector with one of the angular sectors of the rotation range of the in-vessel detection assembly.

[0084] Item 19 - The system according to Item 18, comprising at least one in-vessel detection assembly having a neutron flux detection unit for a source region, and at least one in-vessel detection assembly having a neutron flux detection unit for an intermediate region.

[0085] Item 20 - The system according to any one of items 18-19, wherein each of the multiple in-vessel detection assemblies is configured as an instrumentation control drum, each in-vessel detection assembly comprises a neutron absorber, and each of the neutron flux detectors is embedded in the radially outer surface of the neutron absorber.

[0086] This specification describes various features and characteristics to provide an understanding of the configuration, structure, manufacture, function, and / or operation of the disclosure, including the methods and systems disclosed herein. It will be understood that these various features and characteristics of the disclosure described herein may be appropriately combined, whether or not such combinations of features and characteristics are explicitly described herein. The inventors and applicants expressly intend that such combinations of features and characteristics fall within the scope of the disclosure described herein. Therefore, the claims can be amended to describe any combination of features and characteristics explicitly or essentially described herein, or features and characteristics explicitly or essentially supported herein. Furthermore, the applicant has the right to amend the claims to affirmatively disallow features and characteristics that may exist in the prior art, even if such features and characteristics are not explicitly described herein. Therefore, any such amendments shall not add new matter to the specification or claims and shall conform to the requirements of specification, sufficiency of specification, and additional matter.

[0087] Those skilled in the art will understand that, with respect to the attached claims, the operations described herein may generally be performed in any order. Furthermore, while various operation flows are shown sequentially, it should be understood that these various operations may be performed in an order other than that illustrated, or may be performed simultaneously. Examples of such alternative orders include, unless otherwise specified in the context, repetition, interleaving, interruption, reordering, incremental, preparation, supplementation, simultaneous, reverse, or other variant orders. Additionally, words such as "depending on," "related to," and other past tense adjectives are not usually intended to exclude such variants unless otherwise specified in the context.

[0088] The inventions described herein may have, consist of, or essentially consist of the various features and properties described herein. The words “to have” (and any form of “to have,” such as “has” or “is equipped”), “to possess” (and any form of “has,” such as “has” or “is possess”), “to include” (and any form of “include,” such as “has” or “is containing”), and “to contain” (and any form of “contains,” such as “contains” or “is containing”) are open-ended linking verbs. Thus, a method or system that “has,” “has,” “includes,” or “contains” one or more features and / or properties has, but is not limited to having only, such one or more features and / or properties. Similarly, an element of a composition, coating, or process that “has,” “includes,” or “contains” one or more features and / or properties has, but is not limited to having only, one or more features and / or properties, and may have other features and / or properties.

[0089] As used herein, including in the claims, the grammatical articles “a,” “an,” and “the” are intended to include “at least one” or “one or more” unless otherwise specified. Thus, in this specification, articles are used to refer to one or more (i.e., “at least one”) grammatical objects of the article. For example, “a component” means one or more components and therefore can be one or more components that may be employed or used in the implementation of the compositions, coatings, and processes described. However, it should be understood that the absence of the phrase “at least one” or “one or more” in its usage does not imply that the objects of the grammatical articles “a,” “an,” and “the” are limited to one. Furthermore, the use of singular nouns includes plural forms, and the use of plural nouns includes singular forms.

[0090] In this specification, unless otherwise specified, all numerical parameters should be understood to be preceded and modified in all cases by the word “approximately.” In this case, the numerical parameters have inherent variability characteristic of the underlying measurement technique used to determine the numerical value of the parameter. Not to the effect of limiting the application of the doctrine of equivalents to the claims, each of the numerical parameters described herein should be interpreted using ordinary rounding techniques, taking into account at least the number of significant figures reported.

[0091] Numerical ranges described herein include all subranges encompassed within the described range. For example, the range "1 to 10" includes all subranges (and inclusive) between the stated minimum value "1" and the stated maximum value "10," i.e., all subranges where the minimum value is 1 or greater and the maximum value is 10 or less. Furthermore, all ranges described herein include their endpoints. For example, the range "1 to 10" includes endpoints 1 and 10. The maximum numerical limit described herein is intended to include all subranges encompassed therein, and the minimum numerical limit described herein is intended to include all upper numerical limits encompassed therein. Accordingly, the applicant has the right to amend this specification, including the claims, to explicitly describe any subranges encompassed within an explicitly described range. All such ranges are essentially described herein.

[0092] In this specification, when used particularly in relation to layers, “on top of,” “above,” “across,” and variations thereof (e.g., “applied on top,” “formed on top,” “deposited on top,” “placed on top,” “located on top,” etc.) mean that they are applied, formed, deposited, placed on, or positioned on the surface of a substrate, but not necessarily in contact with the surface of the substrate. For example, a layer “applied” on a substrate does not preclude the presence of another layer or other layer of the same or different composition between the applied layer and the substrate. Similarly, a second layer “applied” on a first layer does not preclude the presence of another layer or other layer of the same or different composition between the applied second layer and the applied first layer.

[0093] While specific examples of this disclosure have been set forth above for illustrative purposes, it will be apparent to those skilled in the art that numerous modifications of the details of this disclosure can be made without departing from the disclosures defined in the attached claims.

Claims

1. A measuring device for determining the power level of the reactor core, The measuring device includes a container detection assembly, The in-container detection assembly is A housing that defines the cavity, The housing is configured to be rotatable in a fixed position, The cavity of the housing is provided with a first angled portion, The rotation range of the housing is composed of a number of angular sectors, and the housing and The housing comprises a detection element positioned in the first angular portion of the cavity of the housing, configured to respond to a neutron flux when the angular displacement of the first angular portion is directed toward the first angular sector of the rotation range. Measuring device.

2. The in-vessel detection assembly is configured to remain within the reactor core cavity for the entire planned lifespan of the reactor core fuel assembly. The measuring device according to claim 1.

3. The aforementioned reactor is a micro reactor. The measuring device according to claim 2.

4. The in-vessel detection assembly is configured to remain in the cavity of the reactor core for approximately eight years or more. The measuring device according to claim 2.

5. The rotation range of the housing is approximately 180 degrees or more. The measuring device according to claim 1.

6. The detection element is embedded in the housing. The measuring device according to claim 1.

7. The housing is equipped with a neutron absorber, The neutron absorber is positioned in the first angular portion of the housing. The measuring device according to claim 1.

8. The detection element is attached to the neutron absorber. The measuring device according to claim 7.

9. The detection element is embedded in the radially outermost part of the neutron absorber. The measuring device according to claim 7.

10. The detection element is configured to respond to the neutron flux in the source region, the neutron flux in the intermediate region, or a combination thereof. The measuring device according to claim 1.

11. The in-vessel detection assembly is configured to protect the detection element from neutron flux when the housing is rotated such that the first angular portion of the cavity of the housing aligns with the second angular sector of the rotation range. The measuring device according to claim 1.

12. The housing is configured to be rotated by a drive device for the control drum of the reactor. The measuring device according to claim 1.

13. It is a control drum for the reactor core, The control drum is A rotatable housing comprising a neutron absorber section, The rotatable housing is configured to rotate within a range of rotation that consists of a number of angular sectors. The neutron absorber section is located at a first angular portion of the rotatable housing, and the rotatable housing is located at the first angular portion of the rotatable housing. The system comprises one or more detection elements configured to respond to a neutron flux and housed in the first angular portion of the rotatable housing, Control drum.

14. The one or more detection elements are attached to the neutron absorber section. The control drum according to claim 13.

15. The control drum comprises a plurality of detection elements distributed axially along the length of the neutron absorber section. The control drum according to claim 14.

16. The one or more detection elements are embedded in the outer surface of the neutron absorber section. The control drum according to claim 13.

17. The one or more detection elements are flush with the outer surface of the neutron absorber section. The control drum according to claim 16.

18. A system for monitoring the output level of a nuclear reactor, The system comprises a plurality of in-container detection assemblies, Each of the above-mentioned in-container detection assemblies includes a neutron flux detection unit that responds to the neutron flux in the source region, the neutron flux in the intermediate region, or a combination thereof. Each of the in-vessel detection assemblies is independently configured to be rotated in a fixed position over a rotational range by the reactor's control drum drive, and each rotational range comprises a number of angular sectors. The system is configured to independently identify the rotation of each of the in-vessel detection assemblies based on the neutron flux level in the reactor. The rotation of the in-container detection assembly includes aligning its neutron flux detection unit with one of the angular sectors of the rotation range of the in-container detection assembly. system.

19. The system comprises at least one in-vessel detection assembly equipped with a neutron flux detection unit for the source region, and at least one in-vessel detection assembly equipped with a neutron flux detection unit for the intermediate region. The system according to claim 18.

20. Each of the multiple container-based detection assemblies is configured as an instrumentation control drum, Each in-vessel detection assembly is equipped with a neutron absorber. Each of the neutron flux detection units is embedded in the radially outer surface of the neutron absorber. The system according to claim 18.

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