In-core instrumentation system

In-core instrumentation system (IN-CORE) which is a replacement of the data acquisition and processing portion of the existing KVRK system... 

In-core instrumentation system—Senses the distribution of the nuclear flux within the core. 

The I C arehitecture is arranged in a hierarchical manner. Above the real-time data network are the systems whose purpose is to facilitate the interaction between the plant operators and the I C systems. These are the operations and control centres system and the data display and the data display and processing system (DDS). Below the real-time data network are the systems and functions that perform the protective, control and data monitoring functions. These are the PMS, the PLS, the in-core instrumentation system, the special monitoring system and the DAS. 

The special monitoring and in-core instrumentation systems do not provide any functions direcdy related to the control or protection of the plant (see subsection 2.1 of AP1000 Instrumentation and Control Defence-in-Depth and Diversity Report, Reference 6.5) and so are not discussed further in this subsection. 

The primary function of the in-core instrumentation system is to provide a three-dimensional flux map of the reactor core. This map is used to calibrate neutron detectors used by the protection and safety monitoring system, as well as to optimise core performance. A secondary function of the in-core instrumentation system is to provide the protection and safety monitoring system with the thermocouple signals necessary for the post-accident inadequate core cooling monitor. The in-core instrument assembhes house both fixed in core flux detectors and core exit thermocouples. 

Nuclear Boiler Assembly. This assembly consists of the equipment and instrumentation necessary to produce, contain, and control the steam required by the turbine-generator. The principal components of the nuclear boiler are (1) reactor vessel and internals—reactor pressure vessel, jet pumps for reactor water circulation, steam separators and dryers, and core support structure (2) reactor water recirculation system—pumps, valves, and piping used in providing and controlling core flow (3) main steam lines—main steam safety and relief valves, piping, and pipe supports from reactor pressure vessel up to and including the isolation valves outside of the primary containment barrier (4) control rod drive system—control rods, control rod drive mechanisms and hydraulic system for insertion and withdrawal of the control rods and (5) nuclear fuel and in-core instrumentation,... 

ZAT a.s., Pribram, Czech Republic. ZAT is responsible for the design, documentation, manufacturing, and installation of the module M2 systems, which are the IN-CORE, SGPS, and PCS systems. The in-core upgrade is the data processing portion only. The in-core instruments (thermocouples and neutron detectors) will not be replaced. 

Distance between the middle and upper plates of the protective tube unit is increased. This allows to increase the bending radius of the guiding channels where the in-core instrumentation elements are arranged. Owing to this upgrading all channels are brought into periphery nozzles of the upper unit that improves the reliability of the in-core measurement system and simplifies its maintenance. 

German KONVOI plants are equipped with a permanent in-core instrumentation. N4 plants have very accurate movable in-core instrumentation with long time response used to calibrate the less accurate ex-core instrumentation used in the core protection system. With the fixed in-core measurements, periodically calibrated by the very quick movable aeroball system, the on-line core surveillance and protection is far more precise and contributes to a significant increase of the safety margins. 

The instrumentation system provides all necessary information for operation of the plant, various signals for displaying, recording, controlling, protecting, annunciating, and the alarm function for the equipment and operational systems. It includes the in-core instrumentation... 

Process instrumentation system—Senses the state of the plant, when used together with the nuclear instrumentation, in-core instrumentation, and digital rod position indication system. 

All control and shutdown devices, and in-core instrumentation are located within tubes perpendicular to the fuel channels and function within the low temperature and low pressure environment of the moderator. All CANDU reactors have two completely independent reactor shutdown systems of different designs, each capable of shutting down the reactor these safety systems are in addition to the reactor regulation system. 

The fest flux test facility (FFTF) was a 400 MW(th) sodium cooled last reactor specifically designed for development and testing of fast breeder reactor fuels, materials, and components. The reactor was a loop-type plant with three parallel heat transport system loops. The plant has neither steam generators nor blanket assemblies for fissile breeding, consistent with its role as a test reactor. The FFTF was equipped with a great deal of instmmentation. Each core assembly was provided with instruments for measurement of sodium flow rates and sodium outlet temperature. Three instrument trees, one of which serves each of the three core sectors, provide outlet instrumentation for all fiiel assemblies, control and safety assemblies, and selected reflector assemblies. In addition, 8 of the 73 core positions were equipped for full in-core instrumentation. Two of these eight positions were available for closed-loop facilities. 

The potentiometer, used for accurate determinations of voltage in standards laboratories, has various applications in biological research. One, of course, is the accurate determination of various bioelectric potentials. In addition, many instruments can be constructed about the potentiometer as a central core. Figure 5.10 illustrates the basic potentiometer circuit. The instrument consists of two batteries, a standard reference cell and a working battery. In some instrumentation systems, the working battery is replaced by a regulated power supply, and a zener diode reference source is used in place of the standard cell. The heart of the instrument is a very accurately calibrated resistance, which is called a slide wire. It is usually in the form of a helix wrapped about a solid core. In operation, switch 1 is connected to the standard cell. The key (switch 2) is tapped at intervals... 

The reactor system (the reactor vessel and integrated head package, reactor internals, fuel assemblies, rod cluster control assemblies, control rod drive mechanisms and in-core instrumentation). 

A design analysis code (COPD) was developed for the system dynamics of the cooling systems. In-core instrumentation, some process instmmentation, sodium leak detectors and steam generator water leak detectors were also developed. 

Sensitivity of chemical shift analysis is determined by the spectral resolution of the XPS system. The resolution of a typical XPS system without a monochromator is 1.0 eV. This corresponds to the intrinsic line width of Al Ka or Mg Ka radiation. The analysing system contributes only little to the overall resolution. This resolution is sufficient to determine the binding energies of most core levels within 0.1 eV. Considerable improvement of the resolution down to 0.3 eV can be achieved by use of a monochromator. The higher resolution has to be paid for by a loss in intensity which, however, is no problem in modern instruments. 

CE instrumentation is quite simple (see Chapter 3). A core instrument utilizes a high-voltage power supply (capable of voltages in excess of 30,000 V), capillaries (approximately 25—lOOpm I.D.), buffers to complete the circuit (e.g., citrate, phosphate, or acetate), and a detector (e.g., UV-visible). CE provides simplicity of method development, reliability, speed, and versatility. It is a valuable technique because it can separate compounds that have traditionally been difficult to handle by HPLC. Furthermore, it can be automated for quantitative analysis. CE can play an important role in process analytical technology (PAT). For example, an on-line CE system can completely automate the sampling, sample preparation, and analysis of proteins or other species that can be separated by CE. 

Problems witbin tbe polisher unit caused operators to respond by attempting to unblock a cboked condition using instrument air. The air was at a lower pressure than the condensate and this caused water to enter the air system. This was not a standard procedure and the commercially supplied polisher unit was not built to standards consistent with the plant. Water in the instrument air system caused several instruments to fail and ultimately initiated a turbine trip. This interrupted heat removal from the radioactive core. The heat generation within the reactor was halted automatically within a few minutes by dropping metal rods to absorb neutrons within the core. 

Indeed this has been recognized for quite some time. For example, Izquierdo et al. point out that Fe dimer is not properly described if the pseudopotential is constructed from the atomic ground state configuration, 3d 4s Instead they use the more appropriate 3d 4s It is also well known that non-linear core corrections [Louie SG, Froyen S, Cohen ML (1982) Phys Rev B 26 1738] are instrumental to recover the right magnetic momentum even in many bulk systems... 

Signals to the Plant Protection and Instrumentation System (PPIS) and the NSSS Control Subsystem (NCS) are supplied by neutron detectors. During power operation, the neutron flux levels are monitored by detectors located in wells between the reactor vessel and the concrete cavity wall. These detectors are distributed symmetrically around the reactor vessel at about the core midplane. During low power operation, starting up, shutting down, and while shut down, the neutron flux levels are monitored by source-range detectors, located in selected side reflector elements near the bottom of the active core. 

Six-control rod subassemblies made of 90% enriched B4C were used in JOYO MK-II and were located symmetrically in the third row. In 1994, one control rod was moved to the fifth row to provide a position for irradiation test assemblies with on-line instrumentation. Since then, the control rod subassemblies have been loaded asymmetrically. The JOYO cooling system has two primary sodium loops, two secondary loops and an auxiliary cooling system. The cooling system uses approximately 200 tons of sodium. In the MK-II core, sodium enters the core at 370°C at a flow rate of 1 100 tons/h/loop and exits the reactor vessel at 500°C. The maximum outlet temperature of a fuel subassembly is about 570 C. An intermediate heat exchanger (IHX) separates radioactive sodium in the primary system from non-radioactive... 

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