1 - Path to Nuclear Through Robotics
Bret Kugelmass: Where did you grow up?
Craig Ranson: Craig Ranson grew up in Central Virginia and his father was on the construction team for North Anna Stations 1 and 2, providing his earliest exposure to nuclear. He later received his degree in Electrical Engineering from Virginia Tech, following his passion for robotics. Ranson interned for B&W Nuclear Services working on steam generator inspections and robotics and controls. The heat exchangers in industry at the time were showing signs of cracking and degradation. One way to mitigate the degradation was to take small metal balls and pound the surface of the tube, putting the tube in compression, called cavitation peening. His first job was designing and testing coils that would see the balls flowing properly. In the early 1990’s, Framatome acquired the commercial nuclear business of B&W Nuclear Services. Nuclear power plants have a stable supply of fuel that services the reactor for a long period of time, but eventually the fuel needs to be replenished. Plants bring in specialty capability to perform special inspections and special component repairs during outages in addition to refueling. Craig Ranson started out as a controls engineers and had the opportunity to travel and take his robotics to the field.
2 - Maintenance and Services for Reactor Equipment
Bret Kugelmass: What are inspection probes used for?
Craig Ranson: Inspection probes can be used to confirm the integrity of the tubular material in steam generators. Corrosion is an issue in generators, but also loose parts that wear the tubes. The industry is on a required inspection regimen for the reactor vessel and reactor vessel internals. The internals include mechanical pieces that hold the fuel and control rods, comprised of a lot of metal, bolts, and welds. The reactor vessel closure head also needs to be inspected because it keeps the pressure of a reactor vessel in place. When Craig Ranson got involved in field deployments, he had some leadership opportunities which led to the opportunity to run a whole engineering organization. Being in management is about motivating the team to get to an end goal, not as much about an individual engineering talent. Ranson saw the company focus more on innovation as industry shifted its needs. Framatome had to innovate and invest in new capabilities, such as being able to replace complete steam generators. For there to be a degradation mechanism on these types of metals, three things must be in play: a caustic environment, a component that is susceptible to cracking, and component must be in tension. Framatome looked at the possibility of taking one factor out of the equation: changing the surface state of the material.
3 - Training and Preparation for Reactor Work
Bret Kugelmass: Can you do something to the surface of the material to change its structural properties?
Craig Ranson: The molecules of the metal are in tension or in compression. Putting it in compression prevents cracking from occurring. High pressure water was used to create cavitation bubbles which hits the surface of the metal at a very high velocity. A customer might have a specific problem or issues, such as replacing a fitting on top of the reactor internals. Framatome was going to use specialty trained SCUBA divers to perform the task. One of the biggest concerns was heat stress and multiple divers were needed to prevent having a heat stress situation. The residual temperature in the water is a little over 100 degrees Fahrenheit. Framatome used the training center in Lynchburg, VA to perform some tests beforehand. They heated the water, put the divers in the pool with different tools, and had them do the testing. Framatome determined they needed to double the number of divers needed to perform the task. Craig Ranson wanted the workforce to come out from the training center fully trained on the conditions and mock-ups. Framatome has multiple mock-ups, including half a reactor vessel that is set up as a pressurized water reactor (PWR) and half set up as a boiling water reactor (BWR) and two fuel handling machines. Fuel handling machines are large cranes that traverse across the pool, retrieve a bundle of fuel underwater, and traverse the fuel to a transfer system which transfers it to the spent fuel building.
4 - Defueling and Refueling Process
Bret Kugelmass: What is the division of responsibilities between the plant operators and the services companies?
Craig Ranson: Services companies have specific responsibilities to go in and work under the overall control of the plant to do specific activities. There are many pre-meetings and challenges between both the plant operators and services companies to ensure both parties are ready to go forward with the activities. The sequence of activities is reviewed, including anticipated challenges how they will be mitigated. Potential pitfalls include physical obstacles not seen on the drawings, schedule conflicts, or any number of things. The process is a controlled, well-oiled machine when it comes to pre-planning. One of the activities Craig Ranson and Framatome supports is reactor defueling and refueling. They bring the senior reactor operators (SRO) to Lynchburg and train together how to remove the fuel. In the 80’s and 90’s, the outages could last as long as 90 days. A typical outage in the U.S. nowadays is between 20-30 days. Pre-planning and innovation, such as robotics and inspection techniques, allows the outage window to be much shorter.
5 - Innovation in the Nuclear Space
Bret Kugelmass: What are some remaining challenges that you would like to see new technologies come to the forefront to solve?
Craig Ranson: There are good technologies that need to be used more fully, such as cavitation peening. Craig Ranson would also like to see utilities get aggressive with mitigating materials and lengthening the maintenance period on the nuclear plants. Framatome sends information out to plants about the latest techniques through trade journals, social media, trade shows, and industry conferences. Different stakeholders, such as engineering directors, CNO’s, and business folks, look at different opportunities and the benefits and costs. The ability to use global positioning systems (GPS) could be used to improve quality in terms of knowing locations on a certain component. There are different repair and inspection techniques which could speed up the quality process of implementing the outage process that have not been discovered yet. Craig Ranson enjoys solving customer problems at the fundamental level. The ninety-nine nuclear plants in the U.S. bring a value to the economy. The industry has seen tough times, but Ranson cannot see a domestic or global economy without nuclear.