Patent Number: 048030392
Section: summary

A portion of the disclosure of this patent document contains material which is subject to copyright protection. The copyright owner has no objection to the facsmile reporduction by anyone of the patent document or the patent disclosure, as it appears in the Patent and Trademark Office patent file or records, uut otherwise reserves all copyright rights whatsoever. BACKGROUND OF THE INVENTION 1. Field of the Invention This invention is directed to a method and apparatus for aiding an operator in executing step by step procedures during the operation of a complex process facility such as a nuclear power plant. More particularly, it involves a computer based system which incorporates monitored plant data and interactive plant operator responses to recommended actions for step by step progression through a selected procedure while simultaneously providing parallel information which allows the operator to assess other plant conditions which may require attention. 2. Prior Art The operation of a complex process facility requires the assimilation of a large amount of data, an evaluation of the status of the process and the various component systems from those data, and informed, decisive action based upon such evaluation. While much of the operation of the modern complex process facility is automatically controlled, overall supervision of the facility is always the responsibility of a human operator. Even in a highly automated facility, there are usually normal operating and maintenance, and in some instances, surveillance procedures, which require action by a human operator. Abnormal and emergency operating conditions invariably call for further intervention by the operator. Typically, the operator of the complex process facility is provided with written or "paper" procedures whereby the steps to be followed are presented in the form of verbal statements on a printed page. These paper procedures require the human who is responsible for carrying out the actions and operations described in the appropriate procedure to read the procedure text, gather specified data and filter the data through preset evaluation logic to identify recommended action steps. The paper procedures often require the human operator to simultaneously monitor other conditions affecting the status of the facility while following the current step by step procedure. In effect, this requires the operator to remember the requirement to monitor the status condition and to periodically check for data related to that condition. One type of facility in which paper procedures are used to guide the human operator in effective management of a complex process is a nuclear power plant. Extensive paper procedures are used in these facilities, especially during emergency conditions following a reactor trip. Subsequent to the accident at Three Mile Island Unit 2 in 1979, the U.S. Nuclear Regulatory Commission issued requirements which have led to a dramatic increase in both the breadth and depth of Emergency Operating Procedures (EOP) at nuclear power plants. In response to these expanded requirements, the Westinghouse Owners Group has developed written generic guidelines which have subsequently been adapted to meet the specific needs and characteristics of the various nuclear generating units represented by the Owners Group and have been issued to the generating crews of the units as Emergency Operating Procedures. These procedures contain explicit directions for the control room operations crew to implement appropriate emergency response strategies. However, the individual charged with implementing such strategies (typically a Senior Reactor Operator [SRO]) remains tied to static procedures, considering changes to plant status in serial fashion, and is potentially unable to properly develop an overview of the plant condition. Commonly owned U.S. Pat. No. 4,552,718 describes a system which generates meaningful information for the operator of a pressurized water reactor (PWR) on six critical safety functions which must be maintained or reestablished, if lost, during emergency operation. The system uses a status tree approach to generate automatically, or through manual responses by an operator, a visual indication of the current status of all six critical safety functions. The display is color coded from green, through yellow and orange, to red to indicate the degree of threat to each safety function. This system is used in conjunction with the paper procedures to alert the operator, who is absorbed in the steps of a particular emergency procedure, to the overall condition of the plant as expressed by the status of the six critical safety functions. The visual presentation also includes the title of the paper procedure to which the operator should turn to find the sequence of steps to be followed in mitigating the effects of the more serious threats to critical safety functions. While the status tree system advises the operator of any threats to the critical safety functions and suggests a procedure to be followed, the operator must still locate the recommended procedure in the paper procedures and then follow it manually step by step. The status tree system also does not keep the operator apprised of other plant conditions which the paper procedures require to be monitored, but which do not directly affect the critical safety functions. Accordingly, it is an overall object of this invention to provide a method and apparatus for aiding the operator of a complex process facility in executing plant procedures. It is a more specific object of the invention to aid the operator of a complex process facility by providing a computer based system and a method of operation which incorporate montored plant data and interactive plant operator responses to recommended actions for step by step progression through a selected procedure. It is a further object of the invention to provide such a system and method of operation which simultaneously, while providing step by step interactive progression through a selected procedure, provide parallel information to the operator concerning other plant conditions which may require attention. It is an additional object of the invention to provide a system and method of operation which generate a permanent record of appropriate system and process conditions at the completion of each step of each procedure or at periodic intervals of time, so that the actual progress of the operator through the procedures can be reconstructed at a later time. SUMMARY OF THE INVENTION These and other objects are realized by a method and apparatus for on-line monitoring of the execution by a human operator of procedures for a complex process facility in which the steps of a selected procedure are sequentially called from storage for presentation on a visual display device as the current step to be performed by the operator. The status of a process condition addressed by the current step is automatically determined by continuous monitoring of selected process parameters for visual presentation to the operator. Where the current values of the appropriate parameters indicate that the existence of a desired condition under consideration by the current step is not verified, a visible textual statement of recommended action to be taken by the operator is selected from a library of textual statements and presented. Visual prompts are also generated to indicate to the operator the steps to take to generate an input signal responsive to the current step. If through the continuous monitoring of the appropriate process parameters a change in the status of a relevant process condition is detected during the time that any one procedure step is current, the displayed statements of conditions and of recommended operator actions and the displayed prompts for operator response are all updated to reflect this change. Thus, the operator's response is always guided by actual current conditions, rather than by those conditions that had existed when execution of the current step was first initiated. By this updating process the effects of operator actions in carrying out a procedure step are incorporated both in the logging of the conditions at the completion of the step and in the prompting of the operator's response at the end of the step. Upon receipt of the response, the next step in the procedure is selected as the current step. Thus the operator always remains in control. Textual statements of the steps are automatically visually presented along with an analysis of current conditions which are the subject of the step, and, where appropriate, suggested action to be taken, but the operator must take the action. Simultaneously with execution of the current steps of the step by step procedure, certain parameter signals representative of other continuously monitored process conditions not being addressed by the current steps are monitored electrically, and when such a parallel monitored process condition is in a state which warrants operator attention, a visual indication of this is presented along with the current step information. This visual indication can take the form of a textual statement of action required in response to the status of this other condition. Priorities are assigned to the action called for by the current step and in response to the other condition and only the prompts associated with the action having the higher priority are presented to the operator. The action called for may be to transfer to another step by step procedure. The operator can indicate his assent by generating a transfer signal which will result in the establishment of a step, usually the initial step, of the new procedure as the current step. The operator may also override the recommended transfer and return to the current step of the active procedure. The overall status of the facility, such as the status of critical safety functions in a nuclear power plant which are determined by a status tree analysis of appropriate monitored parameters, is also monitored by the parallel monitor and visually presented to the operator. When called for, a visual textual statement of a recommendation to transfer to a procedure designed to address the abnormal status of a critical safety function is visually presented with prompts that permit the operator to effect the transfer or to override the recommendation. In the preferred embodiment of the invention, statements of a preselected number of the most recently executed and the next to be executed steps, for example two of each, are visually presented to the operator along with the current step information to provide a broader picture of where he is in the procedure. According to another aspect of the invention, multiple users can execute a single procedure from separate locations. With this arrangement the actions of the multiple users are coordinated to avoid possible conflicts and eliminate the delays associated with coordination through voice communications. In a related embodiment, two or more different procedures can be executed by operators at separate locations or by a single operator at his normal work station while the parallel process monitor feature associated with the execution of each procedure monitors plant parameter data stored in common memory to warn of conflicts with the other active procedure or procedures if any should arise. The tasks associated with carrying out two or more procedures simultaneously may be carried out in separate digital computers or in one computer having sufficient capacity to perform all the tasks. The invention also provides for logging of the time of completion of each procedure step and relevant component and system status including the results of specified operator actions at the completion of each step and overall plant status as indicated by the parallel process monitor feature.