TEPCO Did Not Adopt a Key Lesson Learned from the Accident at Three Mile Island

Unlike their American counterparts, not all control room operators in Japan have access to plant specific training simulators.  Instead, according to a report by NPR, they use “generic” simulators that are similar to, but not identical to their plant.  This difference may have contributed to the difficulties operators had at Fukushima Dai-ichi when responding to complex events that followed the catastrophic earthquake and tsunami on March 11, 2011.

The differences between a generic simulator and a plant-specific one are often in precisely the systems the Fukushima operators were struggling with: electrical power supplies, cooling water, and building ventilation.  These differences matter little when training for events within the design basis of the reactor, but when events stray outside the design basis, include “cascading” failures, and involve severe accident response, generic simulators can’t accurately model the events.  When training for situations that exceed the capabilities of a simulator, instructors are left with fewer, less realistic options like classroom training or “table top” walkthroughs of operator actions.

In my 20+ years as a nuclear plant senior reactor operator, instructor, and manager I spent thousands of hours on plant specific simulators as a student, instructor, and management evaluator.  I can say with certainty the differences between a generic and plant specific simulator matter greatly in the quality of training received by operators! This higher quality training results in operators with greater proficiency in dealing with plant upsets and complex events.  In fact, training on generic simulators is a practice the USA abandoned more than 20 years ago. This shift was but one of  many improvements in training for nuclear workers adopted following the 1979 accident at the Three Mile Island plant.  Today no nuclear plant can be built in the USA without it’s own plant specific simulator, and no operator can be granted a reactor operator’s license without exhaustive training and examination on a plant specific simulator.

My peers from other nations often have not agreed.  Many I have met view plant specific simulators as a costly extravagance, and they still rely on generic simulators.  In addition, generic simulators are often located at some central or distant location rather than on the plant site.  This makes simulator training less frequent and more time consuming because of the travel involved. As a result, operators get far less simulator time per year than their counterparts with local plant specific simulators.

In the USA, nuclear plant control room operators routinely spend one of every five or six weeks in full time training.  Each training week is typically composed of 20 hours of simulator time and 20 hours in the classroom, and includes both written examinations and evaluated scenarios in the simulator. If a team or individual fails to pass an evaluation they do not return to operate the plant until they have been remediated and pass a subsequent re-evaluation.  The result is more than 100 hours of training and evaluation per year on plant specific simulators for every operator.  Compare this to commercial airline pilots who typically attend only one week of simulator training per year, and you begin to get the picture of how highly trained US nuclear plant operators are.  When taking into account initial qualifications, additional training for subsequently higher levels of responsibility, and routine “continuing training”, a typical nuclear plant operator in the USA spends about one-third of their career in training!

While it is too soon to draw conclusions, I suspect the international response to the events at Fukushima Dai-ichi will include improvements in the quality and quantity of operator training, and increased access to plant specific simulators at nuclear plants around the world.   Even if official findings do not include this recommendation, nuclear utilities without plant specific simulators would be wise to consider such an investment at each nuclear plant they operate.


John Wheeler

This Week in Nuclear


Author: John Wheeler

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