Design of double ring lock ring in extensible frequency clock generator chip

With the continuous development of computer technology and the continuous improvement of interface data rate, the clock frequency has reached the demand of several gigahertz, which makes the electromagnetic interference problem very serious. Spread spectrum clock is an effective method to reduce electromagnetic interference of digital chips. Therefore, this paper designs a double-loop phase-locked loop that can spread spectrum and has strong anti-electromagnetic noise interference ability. The designed dual-loop phase-locked loop can be used in the clock generator chip. The overall structure of the circuit consists of a main loop and a secondary loop. The main loop is an adjustable phase-locked loop circuit that can provide an output with a center frequency of 500MHz. The secondary loop can realize the spread spectrum function by charging and discharging the filter capacitor of the main loop loop, and at the same time, the spreading depth can be set by the feedback based on the frequency division. The dual-loop phase-locked loop designed in this paper has a good effect in spread spectrum and anti-electromagnetic interference noise.

Modelling and simulation of house load operation of HPR1000 NPP

In this paper, the house load operation of the unit is evaluated, taking the third-generation Nuclear Power Plant (NPP) HPR1000 as an example, considering the primary loop, the secondary loop and the entire on-site electrical power systems. The main work of this study is as following: Firstly, acceptance criteria and specific numerical requirements are set out; the simulation result should meet the relevant criteria. Secondly, the Simulink simulation model of the entire system is built in detail, which can be divided into primary loop, secondary loop and on-site electrical power system parts, with emphasis on the simulation modelling of the turbine generator unit. The component models of each part and their corresponding connection relationships of each part are shown and given. Finally, a house load operation simulation is performed, and the result is compared with the acceptance criteria to verify that whether the generator has the ability to transfer to house load operation as designed.

Long-Term Simulation of Sodium Dynamics During a Large Leakage Sodium-Water Reaction

The steam generator of the sodium-cooled reactor is the barrier between the secondary and third loops. When the heat transfer pipe breaks, the water/steam will pour into the sodium and a sodium-water reaction will occur. The pressure in the secondary loop will increase and the rupture disks will burst to reduce the pressure. For the safety analysis, the maximum pressure is limited. For the long term, the pressure pulse weakens and the fluid flow tends to a quasi-steady state several seconds or minutes after leak initiation. Therefore, it is necessary to develop a model to investigate the dynamics of the secondary loop in the long term. The continuity equation, the momentum equation and the energy equation are used to derive the sodium flow model in the secondary loop. The sodium pressure and velocity are described by the one-dimensional differential equation. The lumped parameter method is applied and the differential equations are solved by the Euler method. FORTRAN language is compiled to develop the code. Critical equipment, including the steam generator, buffer tank, pump, rupture disks, and accident discharge tank are considered in the secondary loop model. The sodium velocity and pressure responses varying with time can be obtained. Compared with the data from the safety analysis report, the tendency of the sodium velocity and pressure is consistent. It is proved that the model is reasonable and effective to simulate and analyze the actual long-term effects of sodium dynamics.

Dynamic Characteristics Analysis of NuScale in Frequency Domain

NuScale is a small nuclear reactor that relies on natural circulation. Its modular production and inherent safety can not only be used to generate electricity in some remote areas, but also provide energy for water desalination and regional heating. However, the dynamic characteristics of the NuScale are different from those of the traditional PWRs because of its passive characteristic. Therefore, it is necessary to study and analyze the system dynamic characteristics of NuScale. The NuScale PWR model is established based on MATLAB&Simulink. It includes point-reactor kinetics model with six groups delayed neutrons, coolant system and steam generator system. The model is established based on the conservation equations of mass, energy and momentum. And the correctness of the model is verified by the comparison between the steady-state calculation results and the design parameters. Transient calculation results are verified by mechanism analysis. To evaluate the dynamic characteristics of NuScale, the sine function changes with different frequencies in reactor reactivity and feedwater mass flow rate are introduced. The amplitude and phase responses of reactor power, secondary loop steam pressure, secondary loop mass flow rate, secondary loop steam temperature, and coolant average temperature are recorded. Then the Bode plot can be drawn with amplitude and phase responses in different frequencies. To evaluate the NuScale dynamic characteristics, frequency domain analysis is performed.

The Corrosion Degradation Characters of the Secondary Loop Piping in Nuclear Power Plant

Fully understanding the corrosion damage characteristics of the secondary loop pipeline plays an important role in ensuring the safe, stable and economic operation of a nuclear power plant. flow accelerated corrosion(FAC), erosion corrosion(EC), high temperature corrosion(HTC) and under insulation corrosion(UIC) are the main corrosion damage forms of secondary loop pipeline. The damage characteristics of FAC in liquid single-phase flow and vapor-liquid two-phase flow are obviously different. Under specific operating conditions, different EC damages such as flash evaporation, droplet impact, HTC erosion, cavitation corrosion, jet cutting, etc may occur. In this paper, the formation conditions, damage morphology, wall thickness distribution, thinning rate and other characteristics of corrosion damage of secondary loop pipeline in nuclear power plant are compared and analyzed. On this basis, these corrosion damages of the secondary loop pipeline in nuclear power plant could be effectively identified and targeted managed.