Outage FAQ and Potential Jobs - Frequently Asked Questions

1.     Why do outage lengths vary?

Actual outage length depends on the amount of work initially planned and the problems (called emergent work) found during the outage.

2.     What type of work is done during an outage?

At a minimum, a refueling outage involves replacement of about 25% to 35% of the core fuel assemblies. BWR refueling activities will take longer than PWRs because there are almost 4 times the number of fuel assemblies in the BWR. 

Any maintenance work that cannot be done when the reactor and turbine-generator are on-line must be done during an outage. This includes:

• Turbine and generator inspections and modifications  

• Circulating Water Pump, Condenser, Feedwater Pump and Heat Exchanger work

• Steam Generator Eddy Current Inspections, tube plugging and tube sleeving.  

• Reactor and reactor cooling system inspections and work on components connected to the reactor cooling system that cannot be isolated during normal operations.  

• For older BWRs, work in the drywell (since it may be inerted using nitrogen during operation).

• Electrical bus inspections, breaker and relay testing on major 4.16 and 6.9 KV buses

• Transformer inspections and doble testing

• Major safety system components that are not allowed to be taken out of service for extended periods of time during operation.

3.     What is a maintenance outage?

Maintenance outages often are those that are caused by a failure or degradation of a major component that cannot be repaired when the unit is on-line. These can take anywhere from 1 day to 3 months, depending on the component. As an example, a plant might be able to remain at over 500 F for a day to fix a minor problem with the feedwater system, but may be out of service for 3 months or more if a generator fire occurs or a generator transformer explosion occurs.

Maintenance outages cannot be predicted with reliability as can a refueling outage.

4.     Why does the interval for refueling outages vary between plants?

When a refueling outage occurs depends on an overall schedule maintained by the utility for all their plants. The schedule is based on economics. Often, you will not see outages during the summer, because the utility needs the power since demand is often highest throughout the summer. The interval depends on how much new fuel into the reactor (and how high it is enriched).

5.     What types of jobs are contract workers needed for?

Contract workers are often used in major projects - turbine overhauls, steam generator eddy current testing and repair - and modifications. Specialties needed during a given outage will vary and include welders, machinists, millwrights, crane operators.

There is usually demand for radiation protection specialist contractors at any plant during an outage.  

Contractors providing outage support

Contractor and Outage-related Websites

• Nukeworker

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