Safety Improvements In Nuclear Power

Originally Published In The Hawaii Reporter

By Michael R. Fox Ph.D., 

An unrecognized improvement in U.S. nuclear plant safety shows that the lessons of the 1979 Three Mile Island accident still are being taken seriously. Nuclear power wouldn’t be making a comeback in this country unless that was the case.

Industry-wide data compiled by the Institute of Nuclear Power Operations (INPO), a utility organization that monitors nuclear plant safety and operations, shows a dramatic improvement in nuclear plant performance over the past 30 years. Among the changes is a reduction “to nearly zero” of the average number of significant reactor events, especially unplanned reactor shutdowns.

All safety indices show improvement since post-TMI reforms took hold. For example, in 2008 the industrial accident rate dropped to only 0.13 industrial accidents per 200,000 worker-hours. Efforts to protect workers from radiation exposure and to reduce the amount of low-level nuclear waste produced from plant operations have also been successful.

Not surprisingly, the reliability of nuclear plants has risen along with the industry’s safety and operating record. In 2008, the median capacity factor of the 104 U.S. nuclear plants was 91.1 percent, meaning that plants were operating more than 90 percent of the time. That was the ninth consecutive year that the capacity factor was in the 90-percent range. By contrast, in 1979 the average capacity factor at nuclear plants was 56 percent.

The TMI accident occurred just three months after Unit 2 began operating when a valve malfunction compounded by human error in responding to the problem led to a loss of cooling water in the reactor core, exposing the uranium fuel assemblies and causing them to partially melt. One of the lessons that the accident taught us was that the signals on the control panel of a reactor needed to be improved so as to give the operators a clear picture of the state of the reactor at all times. Also, reactor operators needed better training, and weaknesses in some of the specific reactor designs had to be corrected.

Among the many changes that were made following the accident was the installation of site-specific control room simulators at every nuclear plant. The simulators are used as part of a continuous training program that INPO conducts for reactor operators. The goal is to ensure that a serious accident can never happen again.
One of the more important outcomes of the accident was the formation of INPO to conduct independent evaluations of plant operations and share reactor operating experience and lessons learned across the industry. INPO has used this data to set challenging benchmarks against which safety and plant operations can be measured. Though the results of its evaluations are not made public, INPO makes them available to plant managers. And lessons learned are shared among nuclear plant operators in this country and worldwide.

After the Chernobyl accident in 1986, the World Association of Nuclear Operators was established with a mission patterned after INPO’s. Much of the credit for establishing both organizations goes to the late William Street Lee, who was chairman and chief executive officer of Duke Power Co., headquartered in Charlotte, NC Bill Lee, as he was known by colleagues, did much to instill a culture of safety throughout the nuclear industry that continues to this day.

That attention to safety is much in evidence at the TMI plant. Though Unit 2 was lost due to the accident, TMI Unit 1 has continued to operate.
Over the past decade Unit 1 has achieved one of the highest capacity factors in the country and has held four world records for continuous operation by pressurized water reactors, including a 689-day cycle that ended in October 2005.

The improved performance of Unit 1 – and other nuclear plants around the country – has enabled electricity companies to reduce the use of fossil fuel plants, particularly plants fueled with costly natural gas. But it has been the seriousness with which companies have taken safety that’s led to the renewal of operating licenses at nuclear plants and plans for building new plants. Let’s hope nuclear power will be available to meet America’s energy needs well into the future.

Michael R. Fox, Ph.D., is a nuclear scientist and a science and energy resource for Hawaii Reporter and a science analyst for the Grassroot Institute of Hawaii, is retired and now lives in Eastern Washington. He has nearly 40 years experience in the energy field.

He has also taught chemistry and energy at the University level. His interest in the communications of science has led to several communications awards, hundreds of speeches, and many appearances on television and talk shows.

He can be reached via email at

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