Nyhet | 2015-08-27 | 08:59

Detection of weak signals at a nuclear power plant

Master's thesis by Richard Wiik at Linköping University, Cognitive Science.

Supervisors at Vattenfall: Anders Tilstam and Staffan Bram.


Managing safety at a nuclear power plant is about a complex system with demanding technology under time pressure where the cost of failure is exceptionally high. Swedish nuclear power plants has over the last few years introduced Human Performance Tools to advert errors and strengthen control. Among them the Pre-job Briefing (PJB), to detect and detect weak signals. By using the Systematic Resilience Model different views of safety is taken to understand the origin of the signals that leads to a PJB, how the signal is interpreted, re-interpreted and presented. The study took place at a Swedish nuclear power plant and included five days of observations and 20 interviewees. The thematic analysis shows a similarity between mentioned origins of Pre-job Briefings and the intended use of PJB. Characteristics of a High Reliability Organisation is shown in practice by a culture of that one will to have a Pre-job Briefing is enough, that sharp end workers is used as a valuable resource for safety and a systematic support to screen jobs over time without influencing non-job related factors.

All major themes from analysis and discussion can be mapped in the Systematic Resilience Model, which strengthens its validity as a holistic model that combines different views of safety in one coherent model. It proved value as a tool to visualize affecting relations that inhibits and reinforces the use of Pre-job Briefings at the targeted plant.