Apparatus, system, and method for positioning movable elements in a nuclear reactor

Abstract

Disclosed is an apparatus, system, and method for monitoring the position of a control rod disposed within a nuclear reactor vessel under a radiation environment. A data processing unit disposed outside the containment structure includes a processor and a memory storing executable instructions. The reactor vessel includes a plurality of control rods proximate the control rods and a coil stack of a plurality of control rod position indicating coils. A data cabinet mounted on the reactor vessel lid within the containment structure includes an analog multiplexer and communication circuitry. The processor executes instructions to select a control rod position indicating coil via the analog multiplexer, pass signals from the control rod position indicating coils through the analog multiplexer, receive signals from the analog multiplexer via the communication circuitry, and determine the position of the control rod based on the received signals.

Description

Technical Field

[0001] Cross - reference to Related Applications This application claims the benefit and priority of U.S. Patent Application No. 17 / 155,807, filed on January 22, 2021, entitled "NUCLEAR MOVABLE ELEMENT POSITION INDICATION APPARATUS, SYSTEM, AND METHOD", which is incorporated herein by reference in its entirety under 35 U.S.C. § 119(e).

[0002] The present disclosure relates to a system for monitoring the position of movable elements within a reactor vessel, and more particularly, to a system for monitoring the position of control rods within a reactor vessel.

Background Art

[0003] Mechanical movement (insertion, extraction) of movable elements such as control rods within a reactor vessel 8 and the associated position monitoring are necessary functions in the operation of a nuclear reactor. Each instrument performing this function typically terminates with a power cable 17 and one or two position indication cables for returning signals from the instrument to a processing unit. An analog rod position indication (ARPI) system is disposed outside the containment structure, and a digital rod position indication (DRPI) system is disposed in a data cabinet within the containment structure quite far from the reactor vessel head 12. The term instrument as used in this application also includes sensors and detection devices. Known rod position indication cable systems, as shown in FIGS. 1 and 2, typically include multi - pin connector break points 10 disposed at the top of the reactor vessel head 12 and on the pool side of the reactor cavity wall 14. Additional break points 10 can also be disposed between the vessel head 12 and the cavity wall 14. The multi - pin connector break points 10 disconnect each section 16 of the interconnecting cable from the corresponding detection device 18, enabling the reactor vessel 8 to be disassembled for refueling. A typical reactor vessel 8 is equipped with such cable assemblies on the order of 100 or more.

[0004] The removal and installation of cable section 16 is generally part of the “critical path” schedule for downtime for refueling, and typically requires work by a specially trained team of technicians during the initial and final stages of the downtime for refueling to complete the task. Typically, such work takes up an entire shift. The total handling of signal cable section 16 can occupy a full day during a 30-day downtime. While disconnecting the cable also requires additional time, the cost of calibration and immersion during inspection and calibration of the ARPI system in Mode 3 is higher, requiring up to 12 hours. Due to the high cost per hour of critical path time loss, even setting aside the cost of trained personnel, this one-day period makes the cost of a single downtime for refueling very high.

[0005] Furthermore, repeated handling of signal cables increases the likelihood of damage, necessitating repair and / or replacement of the cables and / or associated hardware. Additionally, handling of signal cables must be performed in the radiation zone above the reactor vessel. Eliminating this type of work would eliminate the associated radiation exposure.

[0006] In certain nuclear power plants equipped with ARPI systems, numerous system problems (drift, interference, and numerous single-point failures) occur, resulting in hundreds of hours per operating cycle spent on ARPI system maintenance. The ARPI system is in a critical path for up to 12-18 hours during startup. While a DRPI system could solve most of the ARPI system's problems, there is no inexpensive way to upgrade the DRPI system.

[0007] Almost all nuclear power plants equipped with rod position indicators (RPIs) require the disconnection and reconnection of cables every time the plant shuts down, resulting in numerous cable connection problems. After reconnecting the cables, testing to verify their effectiveness is necessary, which is time-consuming. Furthermore, testing causes cable wear, necessitating replacement every 20-25 years. Troubleshooting the complex systems and numerous problems requires specialized technical experts (SMEs).

[0008] Currently, the electronic components of the DRPI system are located an average of approximately 100-125 feet from the reactor vessel lid 12 inside the containment vessel. This requires disconnecting and reconnecting cables every time the reactor is shut down, which is time-consuming and labor-intensive, and carries the risk of errors during reconnection. Currently, there are 29-61 rods in operating reactors and 69 rods in next-generation reactors.

[0009] Therefore, there is room for improvement in reactor rod position indicator systems used to monitor the position of control rods and other reactor conditions. [Overview of the project]

[0010] In one embodiment, the Disclosure provides a method for monitoring the position of control rods located within a reactor vessel in a radiation environment. The method includes (a) a processor located outside the containment vessel structure selecting a control rod position indicator coil located in a coil stack adjacent to a control rod located within the reactor vessel, via an analog multiplexer located in a data cabinet attached to the reactor vessel lid within the containment vessel structure; (b) a signal from the control rod position indicator coil being transmitted via the analog multiplexer; (c) a signal from the analog multiplexer being received by the processor via a communication circuit located in the data cabinet attached to the reactor vessel lid within the containment vessel structure; and (d) a signal being determined by the processor based on the received signal.

[0011] In another embodiment, the Disclosure provides a device for monitoring the position of control rods located within a reactor vessel in a radiation environment. The device includes a processor coupled to a memory for storing executable instructions, the processor being located outside the containment vessel structure, an analog multiplexer located in a data cabinet attached to the reactor vessel lid within the containment vessel structure, and a communication circuit coupled to the analog multiplexer and the processor. When an executable instruction is executed by the processor, the processor is instructed to (a) select a control rod position indicator coil located in a coil stack adjacent to a control rod located within the reactor vessel via the analog multiplexer, (b) transmit a signal from the control rod position indicator coil via the analog multiplexer, (c) receive a signal from the analog multiplexer via the communication circuit, and (d) determine the position of the control rod based on the received signal.

[0012] In yet another embodiment, the Disclosure provides a system for monitoring the position of control rods located within a reactor vessel in a radiation environment. The system includes a data processing unit located outside the containment vessel structure, the data processing unit having a processor coupled to a memory for storing executable instructions; a reactor vessel located within the containment vessel structure; a plurality of control rods located within the reactor vessel; a coil stack comprising a plurality of control rod position indicator coils, the coil stack located in close proximity to the control rods located within the reactor vessel; and a data cabinet attached to the reactor vessel lid within the containment vessel structure. The data cabinet includes an analog multiplexer and a communication circuit coupled to the analog multiplexer and the processor. When an executable instruction is executed by the processor, it causes (a) to select a control rod position indicator coil located within the coil stack via the analog multiplexer; (b) to transmit a signal from the control rod position indicator coil via the analog multiplexer; (c) to receive a signal from the analog multiplexer via the communication circuit; and (d) to determine the position of the control rod based on the received signal. [Brief explanation of the drawing]

[0013] The various features and advantages of the embodiments described in this application will be explained below with reference to the attached drawings.

[0014] [Figure 1] This is a schematic diagram of a known system for monitoring the state of a reactor vessel.

[0015] [Figure 2] This is a more detailed schematic diagram of a part of the system shown in Figure 1.

[0016] [Figure 3] This disclosure describes at least one aspect of a high-level system for monitoring the position of moving elements within a reactor vessel.

[0017] [Figure 4] A block diagram of an electric circuit of a system for monitoring the position of a movable element in a reactor vessel shown in FIG. 3, according to at least one aspect of the present disclosure.

[0018] FIGS. 5A to 5C are partial views of a high-level multiplexer system divided into several sheets, according to at least one aspect of the present disclosure.

[0019] [Figure 5A] A multiplexer circuit arranged in a storage container structure is shown, according to at least one aspect of the present disclosure.

[0020] [Figure 5B] A communication circuit coupled to the multiplexer circuit shown in FIG. 5A, arranged in a storage container structure, is shown, according to at least one aspect of the present disclosure.

[0021] [Figure 5C] A computer circuit coupled to the communication circuit shown in FIG. 5B, arranged outside the storage container structure, is shown, according to at least one aspect of the present disclosure.

[0022] [Figure 6] A rectifier circuit for rectifying a coil voltage is shown, according to at least one aspect of the present disclosure.

[0023] [Figure 7] A method for monitoring the position of a control rod arranged in a reactor vessel in a radiation environment is shown, according to at least one aspect of the present disclosure.

[0024] The same reference numerals refer to corresponding parts throughout several drawings. It should be understood that the examples described in the present application show one form of various embodiments of the present invention, and such examples do not limit the scope of the present invention in any way.

Mode for Carrying Out the Invention

[0025] The applicant of this application owns the following U.S. patents, the disclosures of which are incorporated in their entirety by reference. U.S. Patent No. 10,020,081, titled "NUCLEAR CONTROL ROD POSITION INDICATION SYSTEM," filed on January 15, 2016. U.S. Patent No. 8,599,987, titled "WIRELESS TRANSMISSION OF NUCLEAR INSTRUMENTATION SIGNALS," filed on October 13, 2009. • U.S. Patent No. 3,893,090, titled "POSITION INDICATION SYSTEM," filed on January 3, 1973, and • U.S. Patent No. 3,846,771, titled "POSITION INDICATION SYSTEM," filed on January 3, 1973.

[0026] The present disclosure will be described in more detail below with reference to the accompanying drawings illustrating embodiments thereof. However, the present disclosure can be implemented in many different forms and should not be construed as being limited to the embodiments shown herein. These embodiments are provided rather for the sake of detail and completeness, so that the scope of the present disclosure will be fully conveyed to those skilled in the art. The same reference numerals refer to the same components throughout the present application.

[0027] Figure 3 shows a high-level system 100 for monitoring the position of movable elements within the reactor vessel 8, according to at least one aspect of the present disclosure. The system 100 includes electronic measurement circuits located in data cabinets A and B, which are mounted on the reactor vessel lid 12 within the containment structure. The electronic circuits located in data cabinets A and B read signals generated by sensors configured to monitor the position of movable elements within the reactor vessel 8. In the aspect shown in Figure 3, the system 100 is configured to monitor the position of control rods 102 and 104 located within the reactor vessel 8.

[0028] The system 100 shown in Figure 3 includes a reactor vessel 8 that houses the core from which control rods 102 and 104 are extended and retracted during a nuclear reaction. In a typical configuration, the control rods 102 and 104 are connected together in a spider-shaped cluster assembly and are extended and retracted into the core by a drive shaft. When actuated by the control rod drive mechanism, the drive shaft moves in a stepwise manner within the pressure housing. The positions of the control rods 102 and 104 relative to the core are determined by coil stacks 106 and 108, each coil stack comprising multiple control rod position indicator coils 110 and 112. For brevity and clarity of disclosure, Figure 3 shows only a single coil stack 106 or 108 for each control rod 102 or 104. In actual embodiments, for redundancy, each coil stack for control rods 102 or 104 consists of alternating A coils and B coils.

[0029] Therefore, a digital rod positioning system such as system 100 schematicly shown in Figure 3 includes coil stacks 106 and 108 for each control rod 102 and 104, respectively, and a digital rod positioning data processing unit 114 that receives signals from data cabinets A and B. The data processing unit 114 processes the signals received from coil stacks 106 and 108 to determine the positions of the control rods 102 and 104. Each coil stack 106 and 108 contains an independent channel of control rod positioning coils 110 and 112, which are located on a pressure housing. Each channel can contain up to 24 control rod positioning coils 110 and 112. The control rod positioning coils 110 and 112 are interleaved and arranged, for example, at intervals of 3.75 inches (9.53 cm) (6 steps). Digital rod position indicating electronics for each coil stack 106, 108 of each control rod 102, 104 are located in a redundant pair of data cabinets A, B attached to the reactor vessel lid 12.

[0030] Although the positions of control rods 102 and 104 are intended to be independently verified, the digital rod positioning system is considered to have an accuracy of within ±3.75 inches (9.53 cm, 6 steps) when both channels are functioning, and within ±7.5 inches (19.1 cm, 12 steps) when a single channel is used. Conventional analog control rod positioning systems, in contrast to conventional digital control rod positioning systems, determine the position of the control rods based on the amplitude of the AC output voltage of an electric coil stack linear variable differential transformer. The overall accuracy of a properly calibrated analog control rod positioning system is considered to be, for example, ±7.2 inches (18.3 cm) (12 steps). Neither conventional analog nor digital control rod positioning systems have the ability to determine the actual positions of control rods 102 and 104. In the DRPI system, the positions of control rods 102 and 104 are known when the DRPI transitions to each Gray code.

[0031] As used in this application, the term "control rod" generally refers to a single unit whose axial position information is individually maintained, such as a group of control rods 102, 104 physically connected in a spider-shaped cluster assembly. The number of control rods 102, 104 varies depending on the plant design. For example, a typical four-loop pressurized water reactor has 53 control rods 102, 104. Each control rod 102, 104 requires its own control rod position indicating coil set 110, 112 having one or more channels, and in the case of a digital system, further digital control rod position indicating electronics associated with each channel are required. Thus, a typical digital control rod position indicating system for a four-loop pressurized water reactor includes, in total, 53 coil stacks, each having two independent channels, and 106 digital control rod position indicating electronics.

[0032] The voltages generated by each control rod position indicator coil 110, 112, configured to monitor the position of each control rod 102, 104, are transmitted by a cable with multiple wires 116, 118, 120, 122. These voltages are passed through several layers of multiplexers and transmitted to the outside of the containment structure by a single wire 124, 126 when redundancy is ignored, or by two wires when redundancy is required. Active reactors contain 29 to 61 control rods 102, 104, while next-generation reactors contain up to 69 control rods 102, 104. Multiple control rod position indicator coils 110, 112 are stacked for each control rod 102, 104.

[0033] Figure 4 is a block diagram of a data processing unit 114 of a system 100 for monitoring the position of movable elements in a reactor vessel, as shown in Figure 3, according to at least one aspect of the present disclosure. The data processing unit 114 includes a logic processor 128 coupled to a memory 130 on which software instructions 132 are installed, an analog input circuit 134, and a digital output circuit 136. The digital output circuit 136 controls analog multiplexers 138, 140 for each data cabinet A, B. Each control rod position indicator coil 110, 112 (Figure 3) has its own binary digital control number. When the digital output circuit 136 switches to a new address, the analog input circuit 134 reads a voltage. This is repeated until all control rod position indicator coils 110 in one coil stack 106 and all control rod position indicator coils 112 in another coil stack 108 have been read. This data allows the position of all control rods 102, 104 (Figure 3) in the nuclear power plant to be determined. This process loops indefinitely. However, this loop can be modified to any combination that includes monitoring of a single coil, for example, which is useful for drop testing of control rods 102 and 104.

[0034] Referring to Figures 3 and 4, in one embodiment, the system 100 according to this disclosure is configured to monitor the positions of control rods 102 and 104 within the reactor vessel 8. In one embodiment, the system 100 for monitoring the positions of control rods 102 and 104 within the reactor vessel 8 includes electronic circuits located in data cabinets A and B, which are directly attached to the reactor vessel lid 12 within the containment structure. This eliminates the need to disconnect thick cables consisting of numerous wires 116, 118, 120, and 122 connected to the control rod position indicator coils 110 and 112 during shutdown, thereby reducing cable and connector wear and saving time and radiation exposure by eliminating the need to perform tests to verify the cables after reconnection.

[0035] In one embodiment, the system 100 replaces the conventional data cabinets A and B of the DRPI system with a modern electronic design. This allows for all instructions and additional functions to be enabled by simply equipping the data processing unit 114, located outside the containment vessel structure, with programmable software 132, thereby increasing the flexibility of the system 100. Conventional DPRI systems locate the control rods 102 and 104 using only electrical / electronic hardware. This hardware reads the voltages of the control rod position indicator coils 110 and 112, locating each control rod 102 and 104 solely by hardware, and transmitting the data to a display system. On the other hand, the system 100 according to at least one embodiment of this disclosure is configured to read all the voltages of the control rod position indicator coils 110 and 112 and input them directly into a computer / processor 128 in the data processing unit 114, which then executes instructions from the software 132 to locate the control rods 102 and 104 and perform all other DRPI functions.

[0036] System 100 according to at least one aspect of the present disclosure offers numerous advantages. For example, if the resistance of one control rod position indicator coil 110 in the coil stack 106 appears to increase over time due to physical wear or the like compared to other control rod position indicator coils 110 or connections in the coil stack 106, the processor 128 can adjust for unexpected abnormal readings by executing instructions in software 132, whereas existing hardware-only DRPI systems cannot adjust for the readings of the control rod positions 102 and 104.

[0037] Furthermore, in system 100 according to at least one aspect of this disclosure, data cabinets A and B are mounted on top of the reactor vessel lid 12. This system 100 overcomes several challenges, including physical space constraints and operation at high radiation levels. By positioning data cabinets A and B and their associated electronic circuits on top of the reactor vessel lid 12, it is no longer necessary to disconnect the DRPI stack cable, consisting of numerous wires 116, 118, 120, and 122 connected to the control rod position indicator coils 110 and 112, during shutdown. This allows nuclear power plant operators to save valuable downtime and costs and improve reliability.

[0038] Due to the high radiation environment, electronic circuits located in data cabinets A and B, such as multiplexers and other active or passive electronic components, contain radiation-resistant electronic components, which may require radiation shielding to meet the radiation and lifespan requirements of the electronic circuits. Radiation testing has shown that commercially available active electronic components, even with reasonable levels of shielding, cannot withstand use at the top of the reactor vessel lid 12. Some passive electrical components, such as capacitors, diodes, and resistors, possess the necessary level of radiation resistance without additional shielding. Therefore, the electronic circuits located in data cabinets A and B employ radiation-resistant multiplexers and other active components.

[0039] [Configuration of an electronic multiplexer] Figures 5A–5C show a high-level multiplexer system 200 divided into several sub-figures according to at least one aspect of the present disclosure. Figure 5A shows a multiplexer circuit 202 located within a containment structure. Figure 5B shows a communication circuit 204 coupled to the multiplexer circuit 202 shown in Figure 5A, the communication circuit 204 being located within the containment structure. Figure 5C shows a data processing unit 114, including a data acquisition computer system, coupled to the communication circuit 202 shown in Figure 5B, the data processing unit 114 being located outside the containment structure. The multiplexer circuit 202 is a detailed embodiment of the analog multiplexers 138 and 140 shown in Figure 4. The communication circuit 204 is housed in data cabinets A and B shown in Figures 3 and 4. The processing unit is also shown in Figures 3 and 4. In one embodiment, the high-level multiplexer system 200 may include redundant control means for redundant components. In another embodiment, the high-level multiplexer system 200 may include a single control means for primary and redundant components, as shown, for example, in Figures 5A-5C.

[0040] The multiplexer circuit 202 shown in Figure 5A and the communication circuit 204 shown in Figure 5B are located in data cabinets A and B, which are positioned on top of the reactor vessel lid 12 (Figures 1 and 3) within the containment vessel structure. Both circuits 202 and 204 include radiation shielding and active components whose radiation resistance is enhanced based on the structure, for example, from 75 krad to a total ionization dose (TID) of over 125 krad.

[0041] The multiplexer circuit 202 is used to read all coil voltages to form a single output and to read the entire system at high speed. The multiplexer circuit 202 consists of a first analog multiplexer 222 and a second analog multiplexer 224. Each of the first and second analog multiplexers 222 and 224 may be, for example, a radiation-resistant 32:1 channel multiplexer. An example of a radiation-resistant 32:1 channel multiplexer integrated circuit is manufactured by Renesas / Intersil.

[0042] Analog coil voltages are transmitted over long distances outside the containment structure, but several conditions are in place to mitigate the long-distance transmission of analog coil voltages. All coil voltages are transmitted on a single wire (A / B coils and redundant components are disregarded). Any contact resistance, wire resistance, and other resistances that change over time equally affect the coil voltages throughout the entire system. The actual coil voltage read by the data acquisition system is not relevant; only the percentage relative to all other coil voltages in each DRPI stack is relevant. For example, under normally expected conditions, if the voltage with the bar is 1.60V and the voltage without the bar is 1.15V, the system will read a differential voltage of 0.45V between the coils. Even if additional wire resistance causes the voltage with the bar to be read as 1.20V and the voltage without the bar as 0.75V, the system can still detect the differential voltage between the two.

[0043] While increased resistance can reduce resolution, System 200 will still read the differential voltage correctly as long as the resistance does not approach an open circuit. Such drastic changes in resistance can occur in any system or design as a result of installation or connection problems.

[0044] All wires and cables within a nuclear power plant are potentially exposed to some degree of noise. Analog signals are generally susceptible to noise because information is transmitted using weak voltages and currents, whereas digital signals transmit information based on bit logic. In low-voltage analog transmissions, a 10mV change due to noise can cause significant fluctuations in the system. However, in System 200, the large voltage difference between the "with" and "without" states prevents such effects. Although the transmitted signal is analog, it closely resembles a 0.45V digital signal because the information only has two states ("with" or "without").

[0045] The multiplexer system 200 includes an interface circuit (not shown), a multiplexer circuit 202, a communication circuit 204, and an AC transformer (not shown), which are located within the containment structure. The data processing unit 114 includes an analog input circuit 134 and a digital output circuit 136 located outside the containment structure. In one embodiment, the circuits are implemented in a modular manner, allowing the metal housing to be modified to accommodate several sizes and configurations.

[0046] [Interface Circuit] The interface circuit performs several functions. The interface circuit includes connectors for connecting to each DRPI coil. In one embodiment, each interface circuit can be configured to connect to, for example, four DRPI stacks. This number four was chosen considering size, module compatibility, and internal wiring connectors. However, those skilled in the art will understand that each interface circuit can be configured to connect to any number of DRPI stacks (e.g., 1 to 3 or 5 or more). The interface circuit includes a 5Ω resistor that needs to be connected in series with each coil. In an embodiment containing 21 coils per coil stack, there are 21 resistors per coil stack, and therefore 84 resistors per interface card.

[0047] A connector is included, which directly supplies the 6VAC required for the coil to the interface circuit (approximately 40 amps). Two connectors (low voltage / low current) are also included, which transmit all coil position voltages from the interface circuit to the multiplexer circuit 202.

[0048] [Multiplexer circuit] Referring to Figure 5A, in one embodiment, the multiplexer circuit 202 multiplexes all coil voltages received from each DRPI coil stack and transmits them to the communication circuit 204 shown in Figure 5B. Similar to the interface circuit, in one embodiment, each multiplexer circuit 202 handles four DRPI coil stacks. Each interface circuit is connected to the multiplexer circuit 202, and all coil voltages of the four parallel-connected DRPI coil stacks are passed to it. This connection is formed by connecting a radiation-resistant ribbon cable or other radiation-resistant wire to a connector on the board.

[0049] Continuing to refer to Figure 5A, the input to the multiplexer circuit 202 is the input A / C voltage from 21 coils 210, 212, and 214. Each received coil voltage 210, 212, and 214 is applied to 21 individual A / C peak detection rectifiers 216, 218, and 220, respectively. For brevity and clarity of disclosure, coil voltage 214 represents the individual coil voltage input from coils 3-21, and each coil voltage is applied to an individual A / C peak detection rectifier 220. For robustness in terms of radiation resistance, in the example shown in Figure 5A, the A / C peak detection rectifiers 216, 218, and 220 are implemented using passive components. An example of passive A / C peak detection rectifiers 216, 218, and 220 is shown in Figure 6.

[0050] Returning to Figure 5A, each coil voltage 210, 212, and 214 rectifies a 50Hz or 60Hz AC voltage to its peak DC voltage. While a data acquisition system outside the containment structure can read the AC voltage, its high sampling rate may prevent it from reliably reading the peak voltage. Therefore, coil voltages 210, 212, and 214 rectify the AC voltage to its peak DC value. Referring also to Figure 6, an example of the passive A / C peak detection rectifier circuit 300 is representative of the passive A / C peak detection rectifiers 216, 218, and 220. The passive A / C peak detection rectifier circuit 300 includes a diode D1-1, a capacitor of appropriate size C1, and a resistor C1. It will be understood that other rectifier circuits, such as op-amp-based rectifier circuits, may be employed. However, for such op-amp-based rectifier circuits to be a viable option, they must be radiation-resistant. The simple passive A / C peak detection rectifier circuit 300 can perform adequately even in the high-radiation environment present at the top of the reactor vessel lid 12 (Figures 1 and 3).

[0051] Referring primarily to Figure 5A, and also to Figure 5B, each coil voltage 210, 212, and 214, once rectified, is supplied to the 32-channel analog multiplexers 222 and 224. Each coil stack has its own multiplexer. All 21 coil voltages 210, 212, and 214 are wired to the first 21 channels of the corresponding analog multiplexers 222 and 224. The outputs 226 and 230 of each coil stack analog multiplexer 222 and 224 are supplied from the multiplexer circuit 202 to the communication circuit 204 (Figure 5B). For example, output 226 of the multiplexer circuit 202, labeled as Card#1 output, is supplied to the Card#1 input 232 of the communication circuit 204. The selector bits for each analog multiplexer 222, 224 are transmitted from the Mux Sel#1 input 244 of the communication circuit 204 and received at the multiplexer selection input 228 of the multiplexer circuit 202. In the example shown in Figure 5A, five selector bits A0, A1, A2, A3, and A4 are used to select one of 21 coil voltages 210, 212, and 214 as inputs to the analog multiplexers 222, 224.

[0052] Each multiplexer circuit 202 can handle four DRPI stacks, so the multiplexer circuit 202 contains a total of eight multiplexers. Each coil stack has its own analog multiplexer 222 and an isolated redundant multiplexer 224. It also includes redundant rectifier circuits 216, 218, and 220 for each coil voltage 210, 212, and 214 (see also the A / C peak detection rectifier circuit 300 in Figure 6), for a total of 168 rectifier circuits.

[0053] In one embodiment, multiplexers 22 and 224 may be Renesas / Intersil radiation-hardened multiplexers (part number ISL71831SEH) with a rated total ionization dose (TID) of 75 krad for low dose rates. Another suitable radiation-hardened analog multiplexer 222 and 224 is a Renesas / Intersil radiation-hardened multiplexer (part number ISL71841SEH), which has an additional feature of a rated TID of 100 krad. Analog multiplexers 222 and 224 can be implemented using any suitable radiation-hardened multiplexer, and it should be understood that the specific components described herein are non-limiting examples.

[0054] [Communication card] Referring primarily to Figure 5B, and further to Figures 5A and 5C, the communication circuit 204 is the interface between the multiplexer circuit 202 and the data processing unit 114 located outside the containment structure. All digital outputs controlling the analog multiplexers 222 and 224 of the multiplexer circuit 202 are received by the communication circuit 204 and then distributed to the multiplexer circuit 202.

[0055] Continuing to refer to Figures 5A-C, the communication circuit 204 includes three 32-channel analog multiplexers 246, 248, and 250. Two of the analog multiplexers 246 and 248 receive the output voltages from the multiplexers of each DRPI stack, such as multiplexer 222 (Figure 5A). Thus, the outputs from 64 analog multiplexers can be reduced to two. The third analog multiplexer 250 reduces the outputs from the other two analog multiplexers 246 and 248 to a single output 254, which is supplied to analog voltage input 1 of the data processing unit 114 located outside the containment structure. The third analog multiplexer 250 uses only two of the 32 input channels, but for simplification and parts availability, it uses the same integrated circuit as the others.

[0056] The selector bits A0, A1, A2, A3, and A4 of the first and second analog multiplexers 246 and 248 on the communication circuit 204 are transmitted from the data processing unit 114 and received at the Mux Sel#2 input 252. The analog multiplexer selector bits A0, A1, A2, A3, and A4 of the analog multiplexers 222 and 224 on the multiplexer circuit 202 are transmitted from the data processing unit 114 and received at the Mux Sel#1 input 256.

[0057] [Data Acquisition Computer System] Referring primarily to Figure 5C, and further to Figures 3, 5A, and 5B, the data processing unit 114 is located outside the containment structure. The data processing unit 114 includes a processor 128 coupled to a memory 130, which also includes executable software instructions 132 for calculating the positions of control rods 102 and 104 based on coil voltages 210, 212, and 214. The software instructions 132 also allow the processor 128 to control the selection of analog multiplexers 222 and 224 in the multiplexer circuit 202, and the selection of analog multiplexers 246, 248, and 250 in the communication circuit 204.

[0058] [Data cabinet placement and design] Referring to Figures 3-5C, two data cabinets A and B, each containing a transformer, interface, multiplexer circuit 202, and communication circuit 204, are mounted on the reactor vessel lid 12. In one embodiment, the individual circuits located within data cabinets A and B, such as the interface circuit, multiplexer circuit 202, and communication circuit 204, are modularized so that they can be configured in single-stack or double-stack configurations within the enclosures of data cabinets A and B. This allows the enclosures of data cabinets A and B to be of different sizes depending on the application, even while using the same electronic equipment.

[0059] Figure 7 shows a method 400 for monitoring the position of control rods located within a reactor vessel 8 in a radiation environment, according to at least one aspect of the present disclosure. This method 400 is implemented with the hardware configuration shown in Figures 3-6. An AC voltage is applied to each control rod position indicator coil 110, 112 in each coil stack 106, 108. According to this method 400, a processor 128 located outside the containment vessel structure selects a control rod position indicator coil 110 located in the coil stack 106 via an analog multiplexer 138 located in a data cabinet A attached to the reactor vessel lid 12 inside the containment vessel structure (402). The coil stack 106 is located in close proximity to the control rods 102 located within the reactor vessel 8. Signals from the control rod position indicator coils 110 are transmitted via the analog multiplexer 138 (404). Signals from the analog multiplexer 138 are received by the processor 128 via a communication circuit 204 (406). The processor 128 determines the position of the control rod 102 based on the received signal (408).

[0060] Referring further to Figure 7, according to this method 400, the processor 128 determines if there is another control rod position indicator coil 110 in the coil stack 106 (410). If there is another control rod position indicator coil 110 in the coil stack 106, this method 400 proceeds along the "yes" branch, and the processor 128 moves on to the next control rod position indicator coil 110 in the coil stack 106 (412), and repeats the functions of select 402, pass 404, transmit 406, and determine 408 until all control rod position indicator coils 110 in the coil stack 106 are selected and read. If there are no more control rod position indicator coils 110 in the coil stack 106, this method 400 proceeds along the "no" branch, and the processor 128 moves on to the next coil stack 108 (414) and repeats the functions of select 402, pass 404, transmit 406, and determine 408 until all control rod position indicator coils 110 in the coil stack 106 are selected and read.

[0061] In one embodiment, this method 400 can be repeated indefinitely to sample all coils 110, 112 within all coil stacks 106, 108 in the reactor vessel 8. In another embodiment, this method 400 can be modified to sample any combination of coils 110, 112 within coil stacks 106, 108, including monitoring of a single coil, which is useful, for example, for drop testing of control rods 102, 104. As mentioned above, there may be up to 21 control rod position indicator coils 110, 112 per coil stack 106, 108, and there may be up to 69 control rods 102, 104 in the reactor vessel 8.

[0062] In one embodiment, this method 400 includes the step of converting the signal to a voltage and reading the voltage signal from selected control rod position indicator coils 110, 112. This method 400 further includes the step of rectifying the voltages read from each of the control rod position indicator coils 100, 112. According to this method 400, the processor 128 determines the position of the control rod 102 based on the received voltage signal (408), whereas in another embodiment, the processor 128 determines the position of the control rod 102 based on the received rectified voltage signal.

[0063] In other embodiments, the signal may be a resistance, current, or other electrical parameter associated with the control rod position indicator coils 110, 112 in each coil stack 106, 108. Thus, this method 400 includes the step of reading the resistance, current, or other electrical parameter associated with the control rod position indicator coils 110, 112 in each coil stack 106, 108, and the processor 128 determines the position of the control rods based on the received resistance, current, or other electrical parameter associated with the control rod position indicator coils 110, 112 in each coil stack 106, 108, and combinations thereof.

[0064] The method 400 further includes the step of routing signals via additional analog multiplexers in a communication circuit 204 located inside the containment structure, thereby coordinating the analog multiplexers 138, 140 with a data processing unit 114 located outside the containment structure. [Examples]

[0065] Various aspects of the subject matter described in this application are described in the following embodiments.

[0066] [Example 1] A method for monitoring the position of a control rod located in a reactor vessel in a radiation environment, comprising: (a) a step of a processor located outside the containment vessel structure to select a control rod position indicator coil located in a coil stack adjacent to the control rod located in the reactor vessel, via an analog multiplexer located in a data cabinet attached to the reactor vessel lid within the containment vessel structure; (b) a step of transmitting a signal from the control rod position indicator coil via the analog multiplexer; (c) a step of the processor receiving the signal from the analog multiplexer via a communication circuit located in a data cabinet attached to the reactor vessel lid within the containment vessel structure; and (d) a step of the processor determining the position of the control rod based on the received signal.

[0067] [Example 2] The method of Example 1, further comprising the step of determining whether there is another control rod position indicating coil in the coil stack.

[0068] [Example 3] The method of Example 2, further comprising the step of selecting a new control rod position indicator coil in the coil stack by the processor when there is another control rod position indicator coil in the coil stack, and repeating steps (b) to (d) for all control rod position indicator coils in the coil stack.

[0069] [Example 4] A method according to one or more of Examples 2 to 3, further comprising the step of selecting a new coil stack by the processor if there are no other control rod position indicator coils in the coil stack, and repeating steps (b) to (d) for all control rod position indicator coils in the new coil stack.

[0070] [Example 5] The method of Example 4, further comprising repeating steps (a) to (d) indefinitely for all coil stacks in the reactor vessel.

[0071] [Example 6] A method according to one or more of Examples 1 to 5, wherein the signal is a voltage, and further comprises the step of rectifying the voltage signal by a passive A / C peak detection rectifier circuit, wherein the passive A / C peak detection rectifier circuit is located within the containment structure.

[0072] [Example 7] The method according to any one of Examples 1 to 6, further comprising the step of controlling the routing of a signal via an additional analog multiplexer in the communication circuit.

[0073] [Example 8] A device for monitoring the position of control rods located inside a reactor vessel in a radiation environment, the device comprising a processor coupled to a memory for storing executable instructions, the processor located outside the containment vessel structure, an analog multiplexer located inside a data cabinet attached to the reactor vessel lid inside the containment vessel structure, and a communication circuit coupled to the analog multiplexer and the processor, wherein when an executable instruction is executed by the processor, the device causes the processor to (a) select a control rod position indicator coil located inside a coil stack adjacent to a control rod located inside the reactor vessel via the analog multiplexer, (b) transmit a signal from the control rod position indicator coil via the analog multiplexer, (c) receive a signal from the analog multiplexer via the communication circuit, and (d) determine the position of the control rod based on the received signal.

[0074] [Example 9] The apparatus of Example 8, wherein when the executable instruction is executed by the processor, the processor is instructed to determine whether there is another control rod position indicator coil in the coil stack.

[0075] [Example 10] The apparatus of Example 9, wherein when the executable instruction is executed by the processor, the processor is instructed to select a new control rod position indicator coil in the coil stack if there is another control rod position indicator coil in the coil stack, and to repeat steps (b) to (d) for all control rod position indicator coils in the coil stack.

[0076] [Example 11] An apparatus according to one or more of Examples 9 to 10, wherein when the executable instruction is executed by the processor, the processor selects a new coil stack if there are no other control rod position indicator coils in the coil stack, and repeats steps (b) to (d) for all control rod position indicator coils in the new coil stack.

[0077] [Example 12] The apparatus of Example 11, wherein when the executable instruction is executed by the processor, the processor causes the processor to repeat steps (a) to (d) indefinitely for all coil stacks in the reactor vessel.

[0078] [Example 13] An apparatus according to one or more of Examples 8 to 12, wherein the signal is a voltage, and further includes a passive A / C peak detection rectifier circuit for rectifying the voltage signal, the passive A / C peak detection rectifier circuit being located within the containment vessel structure.

[0079] [Example 14] The apparatus according to any one or more of Examples 8 to 13, wherein the communication circuit further includes an analog multiplexer that routes signals to the processor via the communication circuit.

[0080] [Example 15] A system for monitoring the position of control rods located inside a reactor vessel in a radiation environment, comprising: a data processing unit located outside the containment vessel structure, the data processing unit comprising a processor coupled to a memory for storing executable instructions; a reactor vessel located inside the containment vessel structure; a plurality of control rods located inside the reactor vessel; a coil stack comprising a plurality of control rod position indicator coils, the coil stack located in close proximity to the control rods located inside the reactor vessel; and a data cabinet attached to the reactor vessel lid inside the containment vessel structure, the data cabinet comprising an analog multiplexer and a communication circuit coupled to the analog multiplexer and the processor, wherein when an executable instruction is executed by the processor, the system causes the processor to (a) select a control rod position indicator coil located inside the coil stack via the analog multiplexer, (b) transmit a signal from the control rod position indicator coil via the analog multiplexer, (c) receive a signal from the analog multiplexer via the communication circuit, and (d) determine the position of the control rod based on the received signal.

[0081] [Example 16] The system of Example 15, wherein when the executable instruction is executed by the processor, the processor determines whether there is another control rod position indicator coil in the coil stack.

[0082] [Example 17] A system of Example 16, wherein when the executable instruction is executed by the processor, the processor is instructed to select a new control rod position indicator coil in the coil stack if there is another control rod position indicator coil in the coil stack, and to repeat steps (b) to (d) for all control rod position indicator coils in the coil stack.

[0083] [Example 18] A system according to one or more of Examples 16 to 17, wherein when the executable instruction is executed by the processor, the processor is instructed to select a new coil stack if there are no other control rod position indicator coils in the coil stack, and to repeat steps (b) to (d) for all control rod position indicator coils in the new coil stack.

[0084] [Example 19] The system of Example 18, wherein when the executable instruction is executed by the processor, the processor causes the processor to repeat steps (a) to (d) indefinitely for all coil stacks in the reactor vessel.

[0085] [Example 20] A system according to one or more of Examples 15 to 19, wherein the signal is a voltage, and further includes a passive A / C peak detection rectifier circuit for rectifying the voltage signal, wherein the passive A / C peak detection rectifier circuit is located within the containment structure.

[0086] [Example 21] The system according to any one or more of Examples 15 to 20, wherein the communication circuit further includes an analog multiplexer that routes signals to the processor via the communication circuit.

[0087] While specific aspects of this disclosure have been described in detail, those skilled in the art will be able to develop various modifications and alternatives to these detailed embodiments in light of the teachings of the entire disclosure. Therefore, the specific configurations disclosed herein are for illustrative purposes only and do not limit the scope of this disclosure, which encompasses the entire scope of the appended claims and all its equivalents.

[0088] A person skilled in the art will understand that, generally, the terms used in this application, particularly in the attached claims (e.g., the main body of the attached claims), are intended to be "open" terms (for example, the term "including" should be interpreted as "including but not limited to," the term "having" as "having at least," and the term "includes" as "include but not limited to"). Furthermore, a person skilled in the art will understand that if the number of matters introduced in a claim is intended to be specific, such intention is explicitly stated in the claim, and if such statement is not present, such intention is not present. For example, to aid understanding, the attached claims may use the introductory phrases "at least one" and "one or more" to introduce the matters to be claimed. However, the use of such phrases should not be interpreted as suggesting that any particular claim containing such introduced claims is limited to claims containing only one such item, even if the indefinite article "a" or "an" is included in the same claim along with an introductory phrase such as "one or more" or "at least one" (for example, "a" and / or "an" should generally be interpreted as meaning "at least one" or "one or more"). The same applies when introducing claims using the definite article.

[0089] Furthermore, even when a specific number of recitations introduced in a claim is explicitly stated, it will be understood by those skilled in the art that such a statement should generally be interpreted to mean at least that number (for example, when "two recitations" is stated without other modifiers, it generally means at least two recitations, or two or more recitations). In addition, in cases where a conventional expression similar to "at least one of A, B, and C" is used, such a construction is usually intended to mean that those skilled in the art will understand the conventional expression (for example, "a system having at least one of A, B, and C" includes, but is not limited to, systems having only A, only B, only C, both A and B, both A and C, both B and C, and / or all of A, B and C). Furthermore, in instances where conventional expressions similar to "at least one of A, B, or C" are used, such constructions are usually intended to be understood in a way that a person skilled in the art would understand the conventional expression (for example, "a system having at least one of A, B, or C" includes, but is not limited to, systems having only A, only B, only C, both A and B, both A and C, both B and C, and / or all of A, B and C). In general, disjunctive words and / or phrases representing two or more selective terms, wherever they appear in the specification, claims, or drawings, should be understood to intend the possibility of including one of those terms, either of those terms, or both of those terms, unless the context interprets them to mean something else. For example, the phrase "A or B" would generally be understood to include the possibilities of "A," "B," or "A and B."

[0090] Those skilled in the art will understand that, with respect to the attached claims, the actions described herein may generally be performed in any order. Furthermore, while the flowcharts of the various actions are shown in sequence, it will be understood that the various actions may be performed in an order different from that illustrated, or may be performed simultaneously. Examples of such alternative orderings may include repetition, interruption, suspension, reordering, augmentation, preliminary, additional, simultaneous, reverse, or other orderings, unless the context requires otherwise. Moreover, terms such as "responsive to," "related to," and other past tense adjectives are not intended to exclude the general forms to which they apply, unless the context requires otherwise.

[0091] It is worth noting that references to “one aspect,” “an aspect,” “an exemplification,” and “one exemplification” mean that the specific features, structures, or properties described in relation to that aspect are included in at least one aspect. Therefore, the phrases “in one aspect,” “in an aspect,” “in an exemplification,” and “in one exemplification,” which appear in various places throughout this application, do not necessarily all refer to the same aspect. Furthermore, specific features, structures, or properties can be combined in any suitable manner in one or more aspects.

[0092] Any patent application, patent, non-patent publication, or other disclosure material referenced in this Application and / or listed in any application data sheet is incorporated by reference to the extent that the incorporated material does not contradict this Application. To that extent, disclosures expressly stated in this Application shall take precedence over any material incorporated by reference that contradicts them. Any existing definitions, views, or other disclosures contained in this Application that contradict them or any part thereof are incorporated by reference, but only to the extent that the incorporated material does not contradict the existing disclosures.

[0093] The words "comprise" and its derivatives (e.g., "comprises," "comprising"), "have" and its derivatives (e.g., "has," "having"), "include" and its derivatives (e.g., "includes," "including"), and "contain" and its derivatives (e.g., "contains," "containing") are non-restrictive linking verbs. That is, a system that "possesses," "possesses," "possesses," or "contains" one or more elements has, but is not limited to having only, those one or more elements. Similarly, an element of a system, device, or apparatus that "possesses," "possesses," or "contains" one or more features has, but is not limited to having only, those one or more features.

[0094] In summary, we have described the many advantages that can be obtained by adopting the concepts described herein. The above descriptions relating to one or more forms are presented for illustrative and explanatory purposes and are not intended to exhaustively or restrictively represent the exact forms disclosed. Modifications or alterations are possible in light of the above teachings. The one or more forms have been selected and described to illustrate the principle and practical applications, thereby making various forms, along with various modifications, available to those skilled in the art for use in specific conceivable applications. The overall scope is intended to be defined by the claims presented with this application.

Claims

1. A method for monitoring the position of control rods placed inside a reactor vessel in a radiation environment, (a) A processor located outside the containment vessel structure transmits a coil address signal via a digital output circuit to an analog multiplexer located in a data cabinet attached to the reactor vessel lid within the containment vessel structure, thereby selecting a control rod position indicator coil located in close proximity to the control rods located within the reactor vessel and within the coil stack; (b) The step of passing the analog signal from the control rod position indicator coil via the analog multiplexer, (c) The processor receives the analog signal from the analog multiplexer via an analog input circuit, via a communication circuit located in the data cabinet attached to the reactor vessel lid within the containment structure, (d) A method comprising the step of the processor determining the position of the control rod based on the received analog signal.

2. The method of claim 1, further comprising the step of determining whether there is another control rod position indicating coil in the coil stack.

3. The method according to claim 2, If there is another control rod position indicator coil in the coil stack, the further step includes selecting a new control rod position indicator coil in the coil stack by the processor via the digital output circuit, A method characterized by repeating steps (b) to (d) for all control rod position indicator coils in the coil stack.

4. The method according to claim 2, If there are no more control rod position indicator coils in the coil stack, the processor selects a new coil stack via the digital output circuit. A method characterized by repeating steps (b) to (d) for all control rod position indicator coils in the new coil stack.

5. The method of claim 4, further comprising repeating steps (a) to (d) indefinitely for all coil stacks in the reactor vessel.

6. The method according to claim 1, further comprising the step of rectifying the voltage signal by a passive A / C peak detection rectifier circuit, wherein the passive A / C peak detection rectifier circuit is located within the containment structure.

7. The method of claim 1, further comprising the step of routing signals via an additional analog multiplexer in the communication circuit.

8. A device for monitoring the position of control rods placed inside a reactor vessel in a radiation environment, the device is A data processing unit including an analog input circuit, a digital output circuit, and a processor located outside the containment structure, coupled to a memory for storing executable instructions, An analog multiplexer located in a data cabinet attached to the reactor vessel lid within the containment vessel structure, The analog multiplexer includes a communication circuit that couples the analog input circuit and the digital output circuit, A device that, when the executable instruction is executed by the processor, causes the processor to perform the following actions: (a) Transmitting a coil address signal to the analog multiplexer via the digital output circuit and the communication circuit to select a control rod position indicator coil located in a coil stack adjacent to a control rod located in the reactor vessel. (b) Transferring the analog signal from the control rod position indicator coil via the analog multiplexer. (c) Receiving the analog signal from the analog multiplexer via the analog input circuit and the communication circuit. (d) Determining the position of the control rod based on the received analog signal.

9. The apparatus of claim 8, wherein when the executable instruction is executed by the processor, the processor is instructed to determine whether there is another control rod position indicator coil in the coil stack.

10. The apparatus according to claim 9, wherein when the executable instruction is executed by the processor, the processor: If there is another control rod position indicator coil in the coil stack, a new control rod position indicator coil in the coil stack is selected via the digital output circuit. A device that causes steps (b) to (d) to be repeated for all control rod position indicator coils in the coil stack.

11. The apparatus according to claim 9, wherein when the executable instruction is executed by the processor, the processor: If there are no other control rod position indicator coils in the coil stack, a new coil stack is selected via the digital output circuit. A device that repeats steps (b) to (d) for all control rod position indicator coils in the new coil stack.

12. The apparatus of claim 11, wherein, once the executable instruction is executed by the processor, the processor causes the processor to repeat steps (a) to (d) indefinitely for all coil stacks in the reactor vessel.

13. The apparatus according to claim 8, wherein the analog signal is a voltage, and further includes a passive A / C peak detection rectifier circuit for rectifying the voltage signal, the passive A / C peak detection rectifier circuit being located within the containment structure.

14. The apparatus of claim 8, wherein the communication circuit further includes an analog multiplexer that routes signals to the data processing unit via the communication circuit.

15. A system for monitoring the position of control rods placed inside a reactor vessel in a radiation environment, the system is: A data processing unit located outside the containment vessel structure, comprising a processor coupled with an analog input circuit, a digital output circuit, and a memory for storing executable instructions, The reactor vessel, which is placed within the containment vessel structure, Multiple control rods arranged within the reactor vessel, A coil stack comprising a plurality of control rod position indicator coils, wherein the coil stack is positioned in close proximity to the control rods located within the reactor vessel, This includes a data cabinet attached to the reactor vessel lid within the containment vessel structure, and the data cabinet is Analog multiplexer and The analog multiplexer includes a communication circuit that couples the analog input circuit and the digital output circuit, A system that, when the executable instruction is executed by the processor, causes the processor to do the following: (a) Transmitting the coil address signal to the analog multiplexer via the digital output circuit and the communication circuit to select the control rod position indicator coil located within the coil stack. (b) Transferring the analog signal from the control rod position indicator coil via the analog multiplexer. (c) Receiving the analog signal from the analog multiplexer via the analog input circuit and the communication circuit. (d) Determining the position of the control rod based on the received analog signal.

16. The system of claim 15, wherein when the executable instruction is executed by the processor, the processor is instructed to determine whether there is another control rod position indicator coil in the coil stack.

17. The system according to claim 16, wherein when the executable instruction is executed by the processor, the processor: If there is another control rod position indicator coil in the coil stack, a new control rod position indicator coil in the coil stack is selected via the digital output circuit. A system that repeats steps (b) to (d) for all control rod position indicator coils in the coil stack.

18. The system according to claim 16, wherein when the executable instruction is executed by the processor, the processor: If there are no other control rod position indicator coils in the coil stack, a new coil stack is selected via the digital output circuit. A system that repeats steps (b) to (d) for all control rod position indicator coils in the new coil stack.

19. The system of claim 18, wherein when the executable instruction is executed by the processor, the processor causes the processor to repeat steps (a) to (d) indefinitely for all coil stacks in the reactor vessel.

20. The system according to claim 15, wherein the analog signal is a voltage, and further includes a passive A / C peak detection rectifier circuit for rectifying the voltage signal, the passive A / C peak detection rectifier circuit being located within the containment structure.

21. The system according to claim 15, wherein the communication circuit further includes an analog multiplexer that routes signals to the data processing unit via the communication circuit.

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