Development of FPGA based reactivity meter

A FPGA based reactivity meter is being developed for PFBR for continuous real-time reactivity monitoring. The reactivity is obtained by implementing solution of inverse point kinetic equations with six groups of delayed neutrons on FPGA. The neutron signal from out-of-core ion chamber is fed to an ADC and digitized signal is used as input for computation of reactivity. The analog output of the computed reactivity is generated using an external DAC. In addition to reactivity calculation, the FPGA also has serial EPROM interface for reading parameters required for solution of point kinetic equations, ADC/DAC control logics and a local LCD display interface. The design range of reactivity is ±20 pcm and response time is less than 100 ms. The external serial EPROM stores the parameter values related to neutron lifetime, delayed neutron fraction, decay constant of delayed neutrons and sampling frequency. The local LCD displays the used parameter values and computed reactivity. VHDL coding of various modules required for this development has been completed. Integration of these modules and functionality testing for various types of signals for verification of reactivity calculations are in progress. The code is targeted to apa600 device of PA series from ACTEL. The implementation details and the tests being carried out in testing of various sub-modules are discussed in this paper. (author)