Nuclear Power Plant Operations

Operation of a Nuclear Power Plant

This section describes the people who operate the plants, what they do, and how they are trained and qualified. More will be added.

A power plant is staffed around the clock. Each unit has a supervisor, control room operators, and auxiliary operators who operate the equipment. At Multi-unit stations there may be a shift manager responsible for the entire site. While the unit is operating, some activities the operators perform include testing safety-significant emergency equipment, support maintenance activities, perform minor maintenance, and process radioactive liquids and gases. During a refueling outage, conducted every 1 to 2 years, the operators will manipulate the fuel and transfer new fuel into the reactor and remove old fuel from the reactor.

Courtesy Seattle Times

This photo shows a boiling water reactor core during a refueling. The core can be seen through ~ 25-40 feet of water.

A fuel handling device or crane operated from above is used to:

attach to the fuel assembly
extract the fuel from the reactor, and
transfer the spent fuel assembly to the storage pool area.

Licensed operators usually perform this activity.

Generally the shift manager and shift supervisors are licensed by the national regulatory agency at a higher level than the control room operators. In the United States the license required is a Senior Reactor Operator's license. To receive this license, the person must demonstrate decision making, accident assessment, supervisory, and team management abilities in a simulator examination. Shift management and supervisory personnel have many years of experience either in an operational or engineering capacity at that station or other stations before they can even take the exam. Written and oral examinations are also required.

The control room operators are licensed at the Reactor Operator level. There is usually one operator who controls the turbine, generator, circulating water and related systems (usually in the same area on the control board). A second operator controls the reactor, reactor cooling and related systems, and the emergency systems (usually in a different area of the control board).

The knowledge, skill, and ability requirements for reactor operators have been specified by the NRC in their NUREG/CR documents - 1122 for PWR and 1123 for BWR. NUREG/CR-1021 describes the examination process and requirements.

Photo by J.A. Gonyeau

This photo shows several licensed operators participating in simulator training.

Simulators prepare operators for activities that they rarely perform (e.g. plant startups, shutdowns, and emergencies). Simulators also reduce the number of times that a power plant's power must be changed.

Ideally, a power plant should run at the maximum allowed power level from one refueling to the next.

The licensed operations personnel must go through ongoing requalification training throughout the year to demonstrate their competence. Included in this training is periodic emergency drill training on a full scope simulator of the control room. This simulator looks just like the control panels with gauges, alarms, controls that function just like the real plant. The simulator is driven by a computer.

For those who are interested in engineering and wondered if there is really an application for differential equations-there is. The simulator design engineers model all the major plant systems so that what the operators see on the simulator is what would be expected if similar events happened in the plant.

The NRC rules govern the use of simulators and the expected fidelity in ability to correctly represent the reference plant performance. In Germany, Ralph Reuhl (training manager of the Biblis plant) has developed a website which describes SIMULA-C, a simplified personal computer-based PWR simulation training tool which enables trainees to understand the dynamic plant behaviour of a PWR plant before using a full scope simulator. In the US, Micro-Simulation Technology has developed a number of PC-based simulation packages, including - Personal Computer Transient Analyzer Advanced Boiling Water Reactor Advanced Reactor Simulators Spent Fuel Pool Accident Simulator. Today, most nuclear plant control room simulators are driven by PC-based programs.