Online Diagnostics of Reactivity Meter for Indian Nuclear Power Plants

An online reactivity meter is developed for use in the Indian Nuclear Power Plants (INPP). The reactivity meter is required to generate reactor trip whenever the calculated reactivity exceeds the predefined limits. The computation of reactivity is based on inverse point kinetic model of the reactor with six groups of delayed neutrons. The recursive equations representing the change in reactivity in response to change in neutron flux have been formulated and solved online for determining the reactivity at any instant using Gate Array. The online diagnostics features have been integrated with the reactivity computation to verify its correctness and healthiness of the meter. The online diagnostic scheme encompasses checking of all the major hardware components, viz. EPROM, ADC, DAC and their interfaces with the Gate Array. It also monitors the robustness of Gate Array and the correctness of the computational cycle algorithms implemented in Gate Array by incorporating suitable checks for stuck bits, improper timings, faulty logic, range crossing, etc., including floating point exceptions. Upon detecting fault(s), limited consecutive attempts towards validation of fault are performed. On confirmation of fault the reactivity computation is halted and output goes to a failsafe state.

The image system of a vortex element in a rigid sphere

It will be shown that a vortex element has the following image system in a rigid sphere immersed in incompressible fluid:(i) A transverse vortex element at the inverse point, equal in strength to minus the transverse resultant of the given vortex element, divided by the ratio of its distance from the centre to the radius of the sphere.(ii) A radial vortex element at the inverse point, equal in strength to plus the radial resultant of the given vortex element, divided by the same ratio.(iii) A uniform line vortex stretching from the inverse point to the centre of the sphere, equal and opposite in total strength to the radial vortex element at the inverse point.

V. The motion of two spheres in a fluid

In the investigation the method of images is followed, and is based on the following lemma. The “image” of a source in an infinite fluid in presence of a sphere consists of a source at the inverse point of the former, and a line sink thence to the centre of the sphere. If the original source be μ at P, the inside source = a /OP μ and the line density of the sink= — μ / a , a being the radius of the sphere. For the analogous a case of fluid within a sphere we, of course, require to have an equal source and sink somewhere within, else there must ensue motion across the boundary. In this case the analysis would give an infinite term for a single source, which, when the quantity of source and sink is zero, disappears.