H.P. Chou

Evaluation of surveillance test interval from risk viewpoint

The paper presents the application of the probabilistic risk assessment (PRA) technique for surveillance test interval (STI) evaluation. Assessment was performed for the reactor protection system (RPS) and based upon the living PRA model of the Taipowers Maanshan power plant. A fault tree was developed and analyzed to find the most proper subsystem for test interval relaxation. Comparisons were made for generic data and plant specific data sets; approaches of staggered test versus sequential test were also compared. Sensitivity studies were made to evaluate the uncertainty of human error and common cause failure factors. Event tree analyses were made to calculate core melt down frequencies for test induced transients and anticipated transient without scram (ATWS) events and to evaluate the effect of STI relaxation. Results indicated that an extension of three times of the current RPS test interval has no significant risk impact for the Maanshan plant.

A fast single slope ADC with vernier delay line technique

The paper presents a 9-bit single slope analog to digital converter (ADC) using a two-level veriner delay line (VDL) technique. The amplitude to time conversion architecture is aim to reduce the errors due to comparator delays and input offset. Results indicated that the comparator timing error has been reduced to less than 10 ps and the offset voltage is less than 1%. The time conversion part has the maximum sampling rate of 50Msps and the time resolution of 19.5ps with the differential non-linearity (DNL) within ±0.5 LSB, and the integral non-linearity (INL) within -0.22 and 0.56 LSB. The ADC has a sampling rate of 5 Msps and is realized with the CMOS 0.18um 1P6M technology.

A High Precision Peak Detect Sample and Hold Circuit

The paper presents a high precision peak detect sample and hold (PDSH) circuit for nuclear radiation spectroscopy. A small compensation current source is applied to reduce the measuring error and improve the resolution. For nuclear pulses with the peak value ranging from 0.1 to 1 volts with a frequency about 100 kHz, test results showed that voltage drop is 2.16muV/mus and the voltage error is less than 0.5 mV.

Construction and evaluation of fault detection network for signal validation

The authors present a methodology which performs evaluation and construction of a sensor failure detection network for nuclear power plant signal validation. The network is arranged in a fault-tree structure which consists of sensors, mathematical models for sensor relations, and decision/estimators derived from parity relations. The evaluation scheme performs a logic state analysis to categorize critical signals and the associated sensors. The construction scheme cooperates with the evaluation scheme to build a detection network automatically using a rule-based algorithm. The package is implemented on a microcomputer and is demonstrated for the nuclear steam supply of a PWR (pressurized water reactor) plant.<<ETX>>

A time-to-digital converter using vernier delay line with time amplification technique

The paper presents a vernier delay line (VDL) type of time to digital converter (TDC) using time amplification technique. The proposed time amplifier (TA) architecture is aim to provide larger input range and higher gain. Simulation results indicated that the maximum deviation between ideal and actual TA transfer curve has been reduced to about 30ps, and the input range and gain are 160ps and 16 respectively. The TDC has maximum sampling rate of about 50Msps when using 200MHz reference clock and the time resolution of 39ps with the differential non-linearity (DNL) within −0.6 and 1 LSB, and the integral non-linearity (INL) within −1.4 and 1 LSB. The TDC is realized using the CMOS 0.18um 1P6M technology.

Nuclear pulse height measurement using FPGA techniques

The present work is to use FPGAs as a digital processor for pulse height measurement. A digital periodic triangle signal is generated by an up-down counter with a positive edge trigger and followed by a synthesizable digital to analog converter (DAC) to generate pulse height information directly. The present pulse height processor is further connected to a personal digital assistant (PDA) to use as a portable spectrometer for field use as a simple nuclide identification tool.

Investigation of data communication systems in lungmen nuclear power plant project

This paper presents an engineering insight of the data communication systems (DCSs) in the Lungmen Nuclear Power Plant Project (LMNPP), in which multiplexing network techniques and software application are used extensively for plant protection, control, and monitoring. The failure modes and effects resulting from using fiber-optical cables for data transmission present potential safety concerns. Issues on coordination and interfaces among the various designers and manufacturers of the instrumentation and control (I&C) systems are evaluated. Furthermore, the network real-time performance, including data flow response time, network data link volume, and loading analysis in normal operation, transient, emergency conditions are studied. The results with specific recommendations and precaution measures are identified.

A FPGA based data acquisition system for research reactor operational monitoring

In this paper, the analysis of digitizing the Campbell channel in wide range neutron monitoring (WRNM) system is introduced first and a digital neutron monitoring system of Campbell channel in Tsing Hua Open-Pool Reactor (THOR) is presented. A field programmable gate array (FPGA) based system for data acquisition and digital signal processing on amplified neutron power signal at THOR will be described. The designed system provides real time data collection and instantaneous signal processing to reduce fluctuation for reactor power, period and reactivity calculation. By further digital signal processing techniques and calibration, the online measuring system is established for experiments at THOR. Finally, for real-time monitoring in THOR, the prototype of digital monitoring system is carried out by shortening the execution time of the current data acquisition system. Compared with the existing analog system, the digital system has a wider dynamic range, less noise in low power range, and a comparable system response time.

Time amplification using closed-loop differential amplifier

This paper describes a new time amplifier (TA) architecture based on differential difference amplifier (DDA) in unity gain buffer configuration. The proposed TA is aim to improve the gain, input range, and capability to control the timing gain. Simulation results indicated that the peak deviation between ideal and actual TA transfer curve has been reduced to about 7ps, and the maximum input range and gain are 60ps and 20, respectively. The TA is also applied to a 9-bit two-stage vernier delay line (VDL) TDC. The TDC has sampling rate of about 8Msps, and the time resolution of 3ps with differential non-linearity (DNL) within -0.5 and 0.9 LSB, and integral non-linearity (INL) within -0.8 and 1 LSB. Both the TA and TDC are implemented using TSMC CMOS 0.18um 1P6M technology.

A digital neutron monitoring system for Tsing Hua Open-Pool Reactor (tHOR)

In this paper, the analysis of digitizing the Campbell channel in wide range neutron monitoring (WRNM) system is introduced and a prototype digital neutron monitoring system of Campbell channel in Tsing Hua Open-Pool Reactor (THOR) is presented. The prototype system consists of a digital oscilloscope along with a portable computer for data acquisition and analysis. The Campbell waveform data is acquired from the preamplifier output of Chin-Shan Nuclear Power Plant (Chin-Shan NPP) and THOR. Various sampling conditions are investigated to obtain an optimal sampling frequency. The measurement result shows good agreement with the present calibrated power data.