Human factors control rooms

HFAM has 20 groups of factors instead of the 10 general failure types of the TRIPOD approach. The reason for this is that all of the 10 TRIPOD GFTs would be applied in all situations, even though the actual questions that make up the factors may vary. In the case of HFAM, it would be rare to apply all of the factors unless an entire plant was being evaluated. HFAM uses a screening process to first identify the major areas vulnerable to human error. The generic factors and appropriate job specific factors are then applied to these areas. For example, control room questions would not be applied to maintenance jobs. 

The term control panel refers to the instrumentation console in a central control room through which process information is communicated to the process worker and via which the worker changes the state of the process. This category includes display elements such as chart recorders, bar indicators, dials, and modem VDU-based systems together with control elements such as buttons, switches, track balls and mice. The control panel is the human-machine interface (see Chapter 2) that has traditionally received the most attention from human factors specialists. 

The human factors audit was part of a hazard analysis which was used to recommend the degree of automation required in blowdown situations. The results of the human factors audit were mainly in terms of major errors which could affect blowdown success likelihood, and causal factors such as procedures, training, control room design, team communications, and aspects of hardware equipment. The major emphasis of the study was on improving the human interaction with the blowdown system, whether manual or automatic. Two specific platform scenarios were investigated. One was a significant gas release in the molecular sieve module (MSM) on a relatively new platform, and the other a release in the separator module (SM) on an older generation platform. 

Kinkade, R. G., Anderson, J. (1984). Human Factors Guide for Nuclear Power Plant Control Room Development, Electric Power Research Institute NP-3659. 

The human factors literature is rich in task analysis techniques for situations and jobs requiring rule-based behavior (e.g., Kirwan and Ainsworth 1992). Some of these techniques can also be used for the analysis of cognitive tasks where weU-practiced work methods must be adapted to task variations and new circumstances. This can be achieved provided that task analysis goes beyond the recommended work methods and explores task variations that can cause failures of human performance. Hierarchical task analysis (Shepherd 1989), for instance, can be used to describe how operators set goals and plan their activities in terms of work methods, antecedent conditions, and expected feedback. When the analysis is expanded to cover not only normal situations but also task variations or changes in circumstances, it would be possible to record possible ways in which humans may fail and how they could recover from errors. Table 2 shows an analysis of a process control task where operators start up an oil refinery furnace. This is a safety-critical task because many safety systems are on manual mode, radio communications between control room and on-site personnel are intensive, side effects are not visible (e.g., accumulation of fuel in the fire box), and errors can lead to furnace explosions. 

The human factor engineering is an essential element of the control room facility design and Man-Machine Interface (MMI) design and its principles are systematically employed to ensure safe and convenient operation. Operating experience review analysis, function analysis, and task analysis are performed to provide systematic input to the MMI design. 

Given the increasing awareness of and focus on human and organization factors involved in areas such as analysis of accidents, validation and verification of new advanced control rooms, and dependable design of various work processes, it is believed that more emphasis will be put on these factors during all the development stages in different applications. 

Wood, X (2004). Control room design. Human factors for engineers. C. Sandom and R. S. Harvey. London, Institution of Electrical Engineers 203—233. 

HMI specifications and applied solutions as Piping and Instrumentation Diagrams (P ID), data formats, types of data obtained, ergonomics of control room and organizational factors directly influencing on operator performance and should be incorporated into HRA analysis. Under consideration should also be taken the performance shaping factors (PSFs), such as stress, estabUshed procedures affecting human operator performance, etc. 

The specific case study aims at analyzing the startup of a gas turbine used to drive the compressor of the butane/propane refrigeration section of an LPG storage and treatment complex. For the start up of the turbine a very specific and detailed sequence of actions is performed. The completion of actions includes tasks performed by operators from the control room as well as by on-site operators. Performance Shaping Factors (PSFs) that influence operators reliability have been identified and their quality has been rated for the specific site according to expert judgment from safety experts and on site observations from the human factor experts of the project. 

As a result of the analysis of events during the accident at the Three Mile Island nuclear plant (TMI, March 1979), the importance of human error in nuclear plants was better understood. The accident resulted from the confusion of the control room operators with inadequate instrumentation and inaccurate procedures. The most important factor was that they had to act in spite of the weaknesses in the training to respond to unexpected events. Therefore, the United States Nuclear Regulatory Commission (USNRC) called for the improvement of Emergency Operating Procedures (EOPs) and in nuclear reactor operator training. The philosophy of incident response implemented in the improved procedures was to take a symptom-based approach (operators foUow a series of yes - no questions to ensure that the reactor core remains covered and only then determine what was the cause of the problem) (USNRC, 2009). 

The main control room panels and other MCR operator interfaces are designed to provide the operator with information and controls needed to safely operate the plant in all operating modes, including startup, refuelling, safe shutdown, and maintaining the plant in a safe shutdown condition. Human factors engineering principles have been incorporated into all aspects of the SBWR MCR design. 

Generic Safety Issue (GSI) I.D.4 in NUREG-0933 (Reference 1), addresses the need for guidance on the design of control rooms to incorporate human factor considerations, and the desirability of endorsing an industry standard for future control room designs. 

The control room should utilize CRT displays and other advanced display technologies. It should be designed only after a full analysis has been made of the control tasks to be performed, and should provide means for data gathering and processing which support operator tasks and decision making. Human factors princples and criteria should be applied to work space, work environment, annunciator warning systems, panel layout and control-display integration. 

Techniques that take account of human factors, such as task analysis, should be used to develop safe, reliable and effective OPs in which account is taken of the layout of the control room, the general design of the plant, and staffing arrangements and operating experience at the plant concerned. 

After the Three Mile Island accident, the USNRC issued interim and long term requirements for improvements in control room design with respect to human factors considerations. Discussion of this matter may be found in the References. 

---