Nuclear Energy Activist Toolkit #9: OpE

June 25, 2013 | 6:00 am
Dave Lochbaum
Former Contributor

Acronyms in the nuclear world are often pronounced as if they were real words. Thus, RCIC (standing for the reactor core isolation cooling system) gets pronounced as “rick see.”

OpE is not pronounced as “oh pee.” Opie was the character played by actor Ron Howard in the old Andy Griffith Show.

OpE is pronounced as “ah pee” (like the nickname Oppy for J. Robert Oppenheimer, a leading figure in the development of the atomic bombs during WWII). It stands for Operating Experience.

OpE’s prominence increased following the March 1979 partial meltdown of the Unit 2 reactor at the Three Mile Island nuclear plant in Pennsylvania. In September 1977, a nearly identical reactor—Davis-Besse in Ohio—took several steps down the same pathway taken at Three Mile Island. But the operators at Davis-Besse recognized conflicting indications caused when a valve failed to the fully open position and stopped the journey to disaster. Information about that near-miss was not shared, denying the operators at Three Mile Island the awareness and training that might have prevented a meltdown.

The nuclear industry and its regulator now have extensive OpE programs. For example, the nuclear industry has EPIX—the Equipment Performance Information eXchange database. Owners upload information about what has worked well and what has not worked well on components at their plants. This information sharing improves overall reliability by helping all follow successful paths and avoid failures.

The NRC also has extensive OpE programs. This post focuses on the NRC’s Operating Experience Smart Sample program while NEAT #10 will cover the NRC’s generic communications program.

The OpESS (I’ve neither a clue nor a care how it’s pronounced) program has its own webpage. Basically, then the NRC identifies an adverse trend from a series of recent events or discoveries, it examines these incidents more thoroughly to determine the underlying common causes. The reports generated by these OpESS evaluations supplement the industry’s information sharing efforts and also enable the NRC make adjustments to its future oversight activities.

For example, OpESS 2012/01, “High Wind Generated Missile Hazards,” resulted in guidance to assist NRC inspector determine areas to examine during two separate inspections: Inspection Procedure 71111.01, “Adverse Weather Protection,” and Inspection Procedure 7111.21, “Component Design Basis Inspection.” Between 2008 and 2011, NRC inspection identified nearly 30 violations associated with inadequate protection against potential missile hazards. The missiles of concern to the NRC aren’t any launched by North Korea or from stealth submarines but rather those that might be created by hurricanes and tornadoes. This OpESS guidance summarized the violations identified between 2008 and 2011. At the Byron nuclear plant in Illinois, for example, NRC inspectors found that the vent lines for the emergency diesel generator fuel oil storage tank were vulnerable to damage by tornado-generated missiles. The vent lines prevent a vacuum from forming inside the tank as fuel oil is transferred to the emergency diesel generators which could cause emergency diesel generator failure due to insufficient fuel supply.

OpESS 2009-02, “Negative Trend and Recurring Events Involving Feedwater Systems,” reported on the evaluation of an anomaly detected in 2008. During 2007, 37 percent of the unplanned reactor shut downs were caused by feedwater related events. Traditionally, such events only cause 15 to 25 percent of the unplanned shut downs. Feedwater is supplied to the reactor vessels of boiling water reactors and to the steam generators of pressurized water reactors to compensate for the steam leaving these components and going to the turbine/generators to make electricity. The feedwater flow input must match the steam flow output in order for the heat produced by the operating reactor core to be properly removed. This OpESS reviewed more than 200 feedwater related findings and determined that 53 percent of the problems involved improperly conducted maintenance or maintenance that should have been performed but was unjustifiably deferred. For example, the OpESS noted that capacitors in the control circuit for a backup feedwater system at the Pilgrim nuclear plant in Massachusetts had a vendor-recommended service lifetime of 7 to 10 years, but had been in use at Pilgrim for over 20 years.

OpESS 2007-03, “Crane and Heavy Lift Inspection,” provided guidance to NRC inspectors about proper control over the movement of heavy objects, like reactor vessel heads and spent fuel dry casks, at nuclear plants. This guidance covered measures intended to reduce the chances that a crane drops a heavy load as well as precautions taken to limit damage done if a load is dropped.

Bottom Line

The NRC’s OpESS program is one of many industry and NRC efforts to share good and bad experiences—the former for emulation, the latter for avoidance. While it’s impossible to count the number of problems avoided by these efforts, the declining trends in forced outages and unplanned reactor shut downs over the past three decades at least suggests they have made positive contributions.

During my year working at the NRC’s Technical Training Center, J Walsh was one of my fellow reactor technology instructors. J often observed that “x [name withheld to protect the guilty] was a fertile ground for OpE.” In other words, OpE serves a useful purpose. But when you start seeing your name pop up often in the OpE on what not to do, it’s likely time to re-evaluate what and how you’re doing things.


The UCS Nuclear Energy Activist Toolkit (NEAT) is a series of post intended to help citizens understand nuclear technology and the Nuclear Regulatory Commission’s processes for overseeing nuclear plant safety.