Ep. 104 - Trace Heffner, Calvert Cliffs Nuclear Plant
1 - Entry-Level Reactor Engineer Duties
Bret Kugelmass: How did you get into the nuclear space?
Trace Heffner: Trace Heffner attended Penn State, initially undecided about which path of engineering he’d like to pursue. As he progressed through school, he gravitated towards careers in which he would be challenged, eventually choosing nuclear engineering over aerospace. The first nuclear class he took, Nuclear 301, was intense because it provided practical, baseline knowledge on quantum physics. Shortly after receiving his Bachelor’s in nuclear engineering, Heffner got a call for an interview from the reactor engineering manager at Calvert Cliffs. He accepted the offer and started at Calvert Cliffs in mid-July 2016. Exelon is very proceduralized and has a process for everything, including training, mentorship, and qualifications. The first year of training includes classroom training to learn about things specific to the plant, industry, and position as well as one-on-one training with the mentors. Heffner shadowed his mentor as he performed monthly tasks, such as reactivity maneuvers, and would perform it the next time with mentor oversight.
2 - Fuel Assembly Storage & Movement
Bret Kugelmass: What various aspects does your role as a reactor engineer entail?
Trace Heffner: A reactor engineering is involved with anything related to the fuel, including developing fuel movement plans. All plants in the U.S. maintain their spent fuel on-site because there is currently no geological repository. Interim spent fuel storage is on-site dry storage that houses the fuel after it leaves the spent fuel pool. Once fuel is discharged from the reactor permanently, it will spend 10 years in the spent fuel pool before being put into a cask and moved to dry storage. When fuel is first received, it goes to a new fuel storage vault for new fuel receipt. From there, fuel goes to the reactor core, then to the spent fuel pool, which can hold around 2,000 fuel assemblies, and finally to dry storage. The locations that fuel is discharged to is strategically selected to minimize the movement that has to take place between discharge and move to dry storage. Water is used as the shield and cooling until it is moved to dry storage, where air starts to cool. Assemblies are moved with very large cranes and crawlers. The loading campaign, when canisters are loaded up, typically happens at Calvert Cliffs in the July timeframe and requires a lot of teamwork and communication.
3 - Radioactive Material Management
Bret Kugelmass: What is startup testing?
Trace Heffner: Startup testing occurs during the startup of the reactor. Whenever the reactor is shutdown for refueling, about one third of the fuel is replaced and all the assemblies are in new locations inside the core. Because of that movement, there is a possibility that the predictions that the vendors and operators have performed may not be exactly as expected. This testing validates whether the predictions run before the cycle will be accurate for another cycle. Nuclear specific parameters are measured to make sure the plant will meet the license for things like shut down margin and see how the core will respond to temperature. The Updated Final Safety Analysis Report (UFSAR) is a licensing or legal document the plan has to follow in operation. During shut down, significantly less heat is produced so not as much coolant flow is required. The special nuclear material custodian (SNMC) is a person who is liable for maintaining cognizance of all the things the Nuclear Regulatory Commission (NRC) sees as special nuclear material (SNM), which are things that contain specific isotopes of plutonium and uranium including fuel and sources that radiation protection uses for calibrating equipment and detectors. Trace Heffner is the spent fuel pool coordinator for non-special nuclear material, which includes keeping track of all the other irradiated things that don’t qualify as special nuclear material but still have doses that need to be tracked, such as filters. All the water in the reactor coolant system and spent fuel pool is filtered, causing low-dose radiation particles and contaminants to accumulate in the filters. They are stored underwater and eventually shipped off-site in large shielded containers during the clean-up campaign.
4 - Intellectually Challenging Reactor Planning
Bret Kugelmass: What aspects of your job do you find intellectually challenging?
Trace Heffner: As a reactor engineer, Trace Heffner finds multiple aspects of his role intellectually challenging. Planning for refueling outages is massive because there is a lot of fuel that is about to be moved and it is complicated to coordinate storage in the spent fuel pool. Development of a reactivity maneuver plan or a maintenance evolution, like a coast down, requires modeling of complex evolutions. Coast down is a function of economics to get the most out of the fuel. Heffner feels that he has matured as a professional very quickly in the nuclear industry and he appreciates the teamwork and effective communication at Calvert Cliffs. He is also the site lead for NAYGN (North American Young Generation in Nuclear). NAYGN works towards four pillars: professional development, public information, community service, and social networking. A big focus in the industry is knowledge transfer between generations.