Plant Stability Analyses

The improved control systems are characterized against the reference control system by plant stabihty analyses. The same perturbations as analyzed for the Super LWR in Chap. 4 are chosen. In this section, the results at BOEC are introduced. Those at EOEC are very similar [31]. 

The same event is analyzed in Sects. 7.9.3 and 7.9.4. The results are shown in Fig. 7.76 [31]. The reactor power settles to the new setpoint at around 100 s with all the control systems. Since the feedwater flow rate follows the reactor power more closely with the improved control systems than the reference case, the changes in the main steam temperature are kept smaller. 

The results are shown in Fig. 7.77 [31]. With all the control systems, the pressure quickly settles to the new setpoint by regulating the turbine control valves. Since the plant response to the valve action is too fast to be affected by the feedwater controller, the peak value of the main steam temperature is almost the same for all the cases. 

The second term of (7.28) in Control system (A) tries to keep the enthalpy rise in the core equal to that in the initial condition. Since the core outlet temperature increases with the pressure when the outlet coolant enthalpy is kept constant, the main steam temperature settles to a slightly higher value than the initial one in this event. However, the difference is 0.7°C, and it does not seem to be a problem in practice. 

The results are shown in Fig. 7.78 [31]. In order to increase the main steam temperature, the power to flow rate ratio needs to be increased by decreasing the feedwater flow rate. The main steam temperature does not reach the new setpoint with control system (A) because the second term of (7.28) tries to make the flow rate follow the power. With other control systems, the main steam temperature settles to the new setpoint 

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The plant dynamics of the Super LWR were understood by plant transient analyses. Although the Super LWR is a thermal spectrum reactor, the reactor power is not very sensitive to the flow rate because the water rods with large volume fraction mitigate fluctuation of the average water density. Based on the plant transient analyses and also referring to LWRs and FPPs, the plant control system of the Super LWR was designed and tuned. Finally, the adequacy of the control system was assessed by plant stability analyses. 

The reactor power is not sensitive to the flow rate because the Super FR is a fast reactor with small reactivity feedback from coolant density. The reactor power is mainly regulated by the CRs. Therefore, the responses of the reactor power do not significantly differ with the four control systems including the reference one. Since the responses of the core and main steam pressures are very fast and determined by only the turbine control valves, they are almost the same with the four control systems. The changes in the main steam temperature obtained by the plant stability analyses are summarized in Table 7.37 [31]. The advantages and the issues of each control system are discussed below. 

The interest in periodically forced systems extends beyond performance considerations for a single reactor. Stability of structures and control characteristics of chemical plants are determined by their responses to oscillating loads. Epidemics and harvests are governed by the cycle of seasons. Bifurcation and stability analysis of periodically forced systems is especially important in the... 

Derivatization is an important aspect of plant hormone analysis as it enhances volatility of many compounds, sometimes it also improves stability, and thereby facilitates analysis by GC-MS. Derivatization can also be used to enhance HPLC separations and improve detection limits. There are numerous derivatives and derivatization procedures. Details of their application to plant hormone analysis can be found in Rivier and Crozier [1] while Knapp [68] provides more general information. 

One of the most important phases of A SW verification and verification assessment is the stability analysis (SA) assessment of digital closed-loop control systems. The requirements of control systems stability is one of the most critical for the NPP safety and must be performed carefully elaborated. Under the SA many important features should be taken into account, particularly input and internal disturbances influence, technological plants nonlinearities and parameters variations, local control systems interconnections, measurement signals corruptions by random noise and so on. 

TLRC can be used for animal, human, and plant metabolism analysis radiochemical purity and stability assessment toxicology and biochemical studies and separation, detection, and quantification of separated radioactive zones of all compound classes. Traditional film autoradiography and LSC continue to be widely used, but phosphor imaging and layer scanners are being increasingly applied. The instruments for these methods are highly automated and... 

NUREG/CR-5816, Wulff, W., et al., "BWR stability analysis with the BNL Engineering Plant Analyser," issued November 1991. 

Design procedures included laboratory tests on polymer rheology, relative permeability, shear degradation, screen factor, stability, and salinity effects. Computer simulations were performed to predict recoveries and to examine optimum polymer concentration. Field injectivity tests were conducted to examine injectivity behavior with time and to gain experience in surface handling of the polymer. Pressure-falloff tests were conducted in conjunction wiA the injectivity tests. Finally, the prqiamtion involved design of the polymer-injection plant and analysis of costs. 

Wulff, W., Cheng, H.S., Mallen, A.N., Rohatgi, U.S., 1992. BWR Stability Analysis with the BNL Engineering Plant Analyzer. Brookhaven National Laboratory Report NUREG/ CR-5816 BNL-NUREG-52312. 

Chapters 3-5 treat the plant system and behaviors. They include system components and configuration, plant heat balance, the methods of plant control system design, plant dynamics, plant startup schemes, methods of stability analysis, thermal-hydraulic analyses, and coupled neutronic and thermal-hydraulic stability analyses. 

Media Si e. Media are supplied in several size grades and the grade used varies at each plant. The finer grades improve media stability, but finer particles are more difficult to recover and the feed rate of these finer-grade slurries should be reduced by a factor of 0.5—0.75 to maintain magnetic recovery. A typical size analysis as used in various heavy-media separation plants treating coal (qv) is given in Table 4. 

Biological Samples. There were three types of biological samples obtained from workers at the plant urine, whole blood, and feces. All urine and blood samples were internally "spiked" at the factory with 1 yg/mL of a nitrosopiperidine (NPiP) standard. NPiP was used for spiking because it has a similar stability and recovery characteristic to nitrosomorpholine, and to provide a means of gauging the accuracy of the analytical methods. Due to the inability to perform homogeneous mixing on-site, the feces samples were not spiked until they were thawed upon return to the laboratory. Ethyl acetate extracts of urine samples were examined for the presence of N-nitrosodiethanolamine (NDEIA), a metabolite of NMOR, by HPLC-TEA. All samples were immediately frozen at the plant (-80°C) and kept at this temperature until analysis. 

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