Patent Number: 044217161
Section: summary

DESCRIPTION 1. Technical Field The present invention relates to fault detection apparatus for monitoring a process plant, such as a nuclear power plant, in order to make critical information available to its operator during abnormal events. 2. Background Art One of the lessons to be learned from the incident at the Three-Mile Island Nuclear Station on Mar. 28, 1979, is that nuclear power plants should be designed to provide information to the operator in an easily assimilated form in order to cope with abnormal events which have not been previously analyzed or experienced. In a report on the incident at Three-Mile Island entitled "Staff Report on the General Assessment of Feed Water Transients in PWRs Designed by B&W" dated May 1979 (NUREG-0560), the Nuclear Regulatory Commission stated: "There will always be a residium of possible but not postulated and analyzed situations. To address this, and as an attempt to extend the defense-in-depth concept, we should study ways to make the operator a more effective recovery agent for incident/accident mitigator. Such a study should look for ways to (a) prevent (inhibit) inappropriate actions, and (b) promote productive intervention. An element of the study that could serve both purposes would be an investigation of methods that would furnish the operator with correct, current, digestible information regarding prinicipal plant conditions (i.e., processes, systems, and equipment). The means by which the operator would best use this information should also be considered, however, such means should not be so rigid as to preclude expedited and improvised actions for the operators for unanticipated phenomena." A primary object of the present invention is to provide an apparatus for monitoring critical systems of a nuclear (process) plant and to provide information as to the status thereof, in summary form, to a plant operator. DISCLOSURE OF THE INVENTION Briefly, the above object is accomplished in accordance with the invention by providing an apparatus which monitors a subset of control panel inputs, the subset being those indicators or plant status which are of a critical nature during an unusual event; Displaying primary information as to whether the core is covered and likely to remain covered, including information as to the status of systems needed to cool the core and maintain core integrity; and, providing a secondary display which can be viewed selectively for more detailed information when an abnormal condition occurs, the primary display having means for prompting the operator as to which one of a number of pushbuttons to press to bring up the appropriate secondary display. In accordance with an aspect of the present invention an apparatus is provided which will make information available to the operator in the essential area of reactor core water inventory by keeping a continuous tally of all outflow and inflow to the reactor pressure vessel, and converting these flows of water level relative to the top of the reactor core. In accordance with an aspect of this invention information is provided to the operator as to whether the water level is rising or dropping, and how much time remains before the core will become uncovered if the water level continues to drop at its current rate. In accordance with an aspect of the invention, a means is provided by which the operator can obtain information as to the status of crucial systems upon request. In accordance with an aspect of the invention information is provided in a summary form to the operator, as opposed to providing information as to the status of the entire system. In accordance with an aspect of the invention, means are provided to monitor a number of reactor systems to make available critical information as to water inventory, power level status, and containment status, and to display this critical information in summary form. In accordance with an aspect of the invention, a backup system calculates the reactor vessel water level based upon an analytical model of the reactor vessel and core. The model involves inflows and outflows of water to the reactor vessel, reactor power, reactor pressure, and reactor water mass. In order to improve the model accuracy, the data is reset periodically during normal operation while the monitor is in standby mode so that the calculated water level is consistent with the actual level as indicated by the directly measured process instrumentation level meters.