Large-Scale Commercial Reactor Segmentation is Now a Reality
Nuclear energy in the U.S. is a vital part of our power system and essential to our national security. While many people are frightened at the thought of nuclear power, it is often a very safe and effective way to generate power for things like homes and businesses. However, even safe nuclear plants sometimes need to be decommissioned, and this process requires careful skill and precision to ensure the highest levels of safety for the surrounding public and environment.
Removing and Disposing of Reactor Vessels
One of the steps that companies must undertake when they are decommissioning a nuclear power plant is to remove and dispose of the commercial reactor vessels. These vessels have a high radionuclide content, which means that they are designated as Greater Than Class C (GTCC) radioactive material. This designation means that the vessels cannot be stored in near-surface-disposal facilities, and in many cases they also cannot be disposed of as a single piece, and must be cut into smaller pieces for proper burial.
Methods for Segmentation and Cutting
There have been many methods proposed for segmenting and cutting reactor vessels, although not all of them have necessarily been used. The proposed methods include:
- Plasma arc
- Abrasive water jet
- Electrical discharge machining (EDM)
- Metal disintegration machining (MDM)
- Plasma saw
- Laser cutting
Record Segmentation Time
The first large commercial reactor vessel to be segmented for disposal was in 2008, but in 2015 EnergySolutions completed the first segmentation of this type using an oxy-propane torch connected to a robotic fixture outside the vessel, a large-scale application of thermal cutting technology. The vessel came from the Zion nuclear power plant, and the new procedure took only one month, significantly shorter than the seven months it took in the 2008 segmentation process using abrasive water jet technology.
The Zion facility was decommissioned after 20 years of use when its owners determined that its continued operation was not going to be feasible given their current financial situation.
The new procedure allowed for the safe and speedy completion of the segmentation process, which is beneficial for the environment and helps ensure the safety of those around the plant. During the process they used specialized rigging and lifting equipment, which was the result of extensive analysis and testing, and ensured that no radiation was released into the environment during the entire process.
As decommissioning continues, segmenting reactor vessels is an important and challenging task, which is why companies like EnergySolutions are constantly working on finding ways to improve the safety and efficacy, shorten the time it takes, and improve technology.