TITANS OF NUCLEAR

1 - Nuclear Material Science

Bret Kugelmass: How did you get interested in the nuclear space?

Kurt Terrani: Kurt Terrani completed his undergraduate degree in materials science at Arizona State University. His interest in large systems drew him to the materials side of nuclear energy, inspired by his childhood dream of being a nuclear physicist. The nuclear industry can do a better job in outreach and education, but recently the Department of Energy Office of Nuclear Energy has started some significant activities in this area. Terrani went to UC-Berkeley for grad school where he worked with Don Olander, a member of the National Academy and the author of “The Fundamental Aspects of Nuclear Fuel Elements”. Olander analyzed and extracted basic, fundamental, transient elements out of big bodies of data for this book. Terrani enjoys making things and doing experimental work, but also the back-of-the-envelope modeling to predict experiment results. If one material is 3D printed and another material is inserted into it, a hybrid material is created after subjection to thermal mechanical treatment. The material goes up in temperature and back down, which creates stress in the material. This stress can be predicted with simple equations as well as finite element analysis.

2 - Path to Oak Ridge National Lab

Bret Kugelmass: What’s the value of doing rough order of magnitude calculations to think of things from a systems perspective?

Kurt Terrani: Looking at things from a systems perspective is a more holistic and complete perspective. People should not be divided between computational and experimental specialties; everyone should have those tools in their toolkit which will provide a more complete understanding of what is going on. Kurt Terrani joined Oak Ridge National Lab in 2010 straight out of his PhD program. He applied for neutron scattering time in 2009 while at Berkeley and was one of the first users of Spallation Neutron Source (SNS). This was one of the first beam lines that backscattering spectrometer came online. One of his advisors recommended that Terrani put his name in the hat at Oak Ridge, which he did, but Terrani didn’t think he would even consider a position. Terrani looked around at the capabilities and materials during a two-day interview and realized that Oak Ridge is the place to be for certain types of research and development.

3 - Transformational Challenge Reactor

Bret Kugelmass: What are some big things happening at Oak Ridge?

Kurt Terrani: One of the big projects currently going on at Oak Ridge National Lab is the Transformational Challenge Reactor (TCR). The vision is not to pick a reactor technology, but instead to find a new way to design, develop, deploy, and license nuclear energy systems. The technology used in the nuclear industry worldwide is late 1940’s and 50’s technology that is efficient, but uses less than a dozen materials across all the nuclear energy systems. These materials are pre-1970’s materials that mostly existed before the dawn of the nuclear era. Licensing and qualifying is being done now as it has always been done, but it’s getting more expensive. Material science has come a long way and, with phenomenal computational tools, materials can be designed for a specific function since there is a profound understanding of radiation effects in materials and incredible characterization capabilities. TCR combines massive computational power, advanced manufacturing, and advanced material science to do things differently. Advanced manufacturing can fundamentally disrupt the way things are designed and there is freedom from constraints such as geometry. When additive manufacturing is used in advanced monitoring, things like acoustic or infrared signals can be continuously monitored as it is built, providing a massive data set. This in-situ data is combined with ex-situ data in a supercomputer to find links between signatures during advanced manufacturing and final performance of conformance to a certain set of criteria.

4 - Material and Manufacturing Qualification Process

Bret Kugelmass: Has economic analysis been done on the cost drivers for nuclear components?

Kurt Terrani: Most of the money in large, gigawatt nuclear plants is in the construction of concrete and steel. Small modular reactors (SMR’s) and microreactors are much more manageable. However, the interesting, ambitious designs are limited by previously qualified components and types of manufacturing that produce their product economically since they already exist. Kurt Terrani’s passion and focus is, after 50 or 60 years, having a dozen materials available people to realistically consider in their designs and different avenues to realize the construction of their reactor systems. The Transformational Challenge Reactor (TCR) at Oak Ridge National Lab (ORNL) is a blueprint and another tool in the toolbox for realizing advanced systems in ways that were not previously possible. Post-Fukushima, ORNL went in search of advanced cladding materials to replace zirconium, since zirconium generates heat and hydrogen during accidents. The team picked out an alloy and spent a few years proving it out before it was deployed in a commercial nuclear power plant, GE’s Hatch 1 in Georgia. The goal of TCR is to advance manufacture a nuclear core and make it go critical and generate heat. The way the new blueprint will be adopted is by educating colleagues in industry, especially the regulator. Doing a complete demonstration that complies to requirements using existing rules and providing additional data showing how computational approaches were used in combination with advanced manufacturing to certify that things will function will get the conversation started to design manufacturing qualification license.

5 - Design and Demonstration of New Nuclear

Bret Kugelmass: What comes first: taking an advanced manufacturing reactor critical or proving to the regulatory body that it is safe?

Kurt Terrani: That National Labs need to be pushing the boundaries. There are multiple pathways, including Department of Energy (DOE) rules and Nuclear Regulatory Commission (NRC) rules. The DOE regulatory space has a lot of computational tools available. Design and safety analysis is completed and presented to a safety analysis board who completes a review and makes a recommendation on moving forward or not. The NRC rules have flexible rules for research reactors. Labs ultimately rely on calculations and assumptions on the source term and bounding scenarios to show that the risk is minimal. Oak Ridge National Labs (ORNL) has nuclear facilities that new companies, startups, or existing companies don’t have, such as hot cells and demonstration pools that are there to be used. With his materials education and focus, Kurt Terrani advocates that that materials are key to performance. It is a problem that no more than a dozen materials are used in existing nuclear systems. His passion is understanding how to push materials to extreme levels of radiation damage and chemical evolution under extreme gradients.

1 - Fusion Energy

Bret Kugelmass: Tell me about some of the things going on here at Oak Ridge National Labs.

Phil Ferguson: Phil Ferguson is the director of fusion and materials at Oak Ridge National Labs. The ITER U.S. home is at the Oak Ridge National Labs; it is the next step in fusion energy. At this step, the alpha particles coming off of the fusion reaction heat the plasma so external energy is no longer required to keep the plasma at 100 million degrees. Once it gets to a point in which the plasma heats itself, the energy can be pulled off and it can be made into a viable electricity source. Ferguson started out at Missouri University of Science and Technology where he got his PhD. He went to Los Alamos for a summer which turned into two and a half years when they had an issue with the spallation target system. Spallation happens when a piece of the nucleus is broken off, leaving the nucleus in a very energetic or excited state. It wants to become stable as quickly as possible causing it to throw off particles, including neutrons. This timing can be used to do condensed matter physics. In order to achieve spallation, you need a particle at some significant fraction of the speed of light through the use of an accelerator.

2 - Spallation Neutron Source

Bret Kugelmass: What is thrown at the nucleus in a fusion reaction?

Phil Ferguson: Protons, charged particles that are either H-plus or H-minus, are accelerated and thrown at the nucleus to cause a fusion reaction. Plasma is the most common form of matter in the universe, except on Earth. A plasma is created and charged particles, or protons, can be pulled off from the ion source. Plasma is created by heating a gas or a mixture of particles to a certain temperature so it is no longer atoms but instead a pool of electrons and ions. A series of cavities alternate charge states, one end being positive and one end being negative. As the proton comes out, it gets pulled by the negative end and simultaneously pushed by the positive end. The fields in the mile-long accelerator are then flipped as the proton reaches the end; the timing has to be down to the microseconds or nanoseconds. A neutron-rich target, such as a heavy metal or liquid mercury, is placed at the end to cause spallation. The Spallation Neutron Source (SNS), a 1 GeV accelerator, puts that beam incident on a liquid mercury target and for every proton that goes into the target there are about 23 neutrons from the chain reaction. The low-energy component does not have any directionality, but the high-energy component goes in the forward direction. SNS has hundreds of people that study everything from the ion source, quadrupole magnets, the accelerating cavities, the target itself, and the moderators. Experiments at SNS range from fundamental properties of magnets to how drugs are absorbed in the body.

3 - Material Characterization with Neutrons and Photons

Bret Kugelmass: How are neutrons and photons used for material characterization differently?

Phil Ferguson: Neutrons and photons are complimentary. X-rays provide a very bright, intense beam that cannot be achieved with neutrons. However, neutrons can get penetration deep in the material that cannot be provided with x-rays and can get isotopic tailoring. Photons typically show the electronic structure. Neutrons allow one to look at the difference between its cross-section between hydrogen and deuterium since it is a weakly interacting particle. One scattering experiment looked at corrosion in a steam generator which had very thick steel structures. In order to seem inside the structure without destructive testing, neutrons could be used to penetrate through the thick steel wall to look for residual stress or issues in the welding process. While in grad school, Phil Ferguson worked at Los Alamos where he was exposed to the accelerator and studied there on an existing spallation source after getting his PhD. The U.S. was making a push to regain some leadership in neutron scattering and decided to build a spallation source at Oak Ridge National Labs. Ferguson was one of three who formed the initial neutronics or spallation physics team at the Oak Ridge spallation source. His team focused on the design of the target station, specifically how to get the most neutrons and still remove the heat from the target to run reliably. They decided on a liquid mercury target for the Oak Ridge Spallation Neutron Source (SNS).

4 - Fusion in Industry

Bret Kugelmass: How long did it take from concept to commissioning for the Spallation Neutron Source?

Phil Ferguson: Phil Ferguson arrived at the Spallation Neutron Source (SNS) in 2000. The first beam on target was in 2006. Ferguson helped design and commission the target station and was then promoted to be over the entire target station. He moved into neutron source development, taking various steps in spallation until 2012 or 2013 when he took his current job as the Director of Fusion and Materials for Nuclear Systems at Oak Ridge National Labs. Ferguson wanted to move away from the operational side of the work and back into the source design side. In the 1980’s and 1990’s, industry was involved in fusion and there was a lot of money and effort in the technology. Through various changes, the funding in fusion in the U.S. went down significantly and a lot of the industry left fusion, making it more of a science as opposed to a strong drive towards an energy source. At the time, the decision was made that fusion was not a high priority and the technology was not ready for the rapid advancement thought to lead to a quick power source. ITER is the last big step in the physics chain which looks at how physics will change with self-heated plasma.

5 - The Fuse Cycle

Bret Kugelmass: Tell me about how the energy from one reaction helps perpetuate the next reaction in self-heating plasma.

Phil Ferguson: For fusion to take place, there must be three things: there must be enough atoms, they must be hot enough, and they must be held together long enough to fuse. To start that process requires a lot of energy. The energy to be taken away from fusion is not necessarily the heat that heats the plasma. The helium atom has a very short range and heats the plasma. A 14MeV neutron comes off with a very long range and is captured and used to make another triton. Energy is released in that process and is the majority of the energy to be captured and used for electricity. Fusion is a two-step process. The first step is creating a very intense source of neutrons. The second step is doing what’s required to close the fuse cycle to continue the reaction by fueling it and to extract energy. The boundary layer on the plasma is sometimes not stable and collapses, causing core plasma to reach out and touch the wall. Changing the magnetic field may be used to ensure the fuel does not collapse and reach out and touch the wall.

6 - Fusion Nuclear Science

Bret Kugelmass: How is the pellet system used in a fusion reaction?

Phil Ferguson: Changing the composition and size of the pellet can be combined with different techniques to impact the plasma in different ways, such as releasing energy. The plasma must be fueled, the fuel cycle must be closed, and the neutrons must be slowed to be absorbed in lithium and create tritium. The first wall is where the plasma reaches out and touches. In order to be as efficient as possible and close the fuel cycle, the first wall needs to be integrated with the first wall of the blanket. A structure material needs to be compatible with the plasma, since the wall erodes and part of the material goes into the plasma. Certain materials can poison the plasma over time and terminate the reaction. Just outside the first wall is a material stack that cools the wall and, as soon as possible, the neutrons should be absorbed into material to produce tritium. There is not a blanket concept or material that works. There is no material yet that meets all the specifications in terms of temperature operating windows, internal radiation damage, and the helium generated at these energies to build a tokamak. The Cadarache in the South of France is the ITER site, which is the big international collaboration designed to study burning plasma physics. Tokamaks are needed to optimized on the fusion nuclear science. The Chinese Fusion Engineering Test Reactor (CFETR) is a bit ahead of the U.S. Fusion Nuclear Science Facility (FNSF). The ITER track studying the physics could be combined with fusion science and technology aspects to form a demonstration reactor.

7 - Challenges in Fusion Technology

Bret Kugelmass: What are the challenges in developing fusion along with the national science approach and the challenges the more aggressive private industry faces?

Phil Ferguson: Burning plasma physics is going to be important for everyone involved in fusion. There are large instabilities called destructions; a disruption is a magnetohydrodynamic (MHD) instability in which the entire plasma, 500 MW, is lost in one location. Closing the fuel cycle is another challenge. Because of the existing fission reactors, especially the CANDU reactors, there is a significant supply of tritium but it will dwindle because it decays at 5% per year. Creating the fusion fuel source, tritium, in-house with fission reactors is an economic benefit to fusion. Everyone needs a material from which to build their device. The ones that operate deuterium-tritium (DT) fusion will have the same issues in terms of materials. Some of the private fusion ventures envision using liquid metals which interact with material. Lead lithium interacts with the structural materials, causing embrittlement or corrosion. Lead lithium creates tritium in situ, it flows and can be used as a heat removal device, and acts as a good shield. ITER is a very large, expensive facility; making the device smaller is critical. High temperature superconducting magnets produce a stronger field which increases the density of the atoms. This would allow the tokamak to be smaller while still achieving burning plasma.

8 - Innovating Magnetic Fields

Bret Kugelmass: What temperature do high temperature superconducting magnets operate at?

Phil Ferguson: High temperature superconducting magnets typically operate on hundreds of Kelvin. If liquid helium isn’t needed to cool the magnets, there is a tremendous savings in what needs to be done in cooling. REBCO is a rare-earth material that can be made in a very strong magnetic field into a very thin tape. Those tapes can be used to construct a magnet for a tokamak which could double the field size or more. Radiation can displace atoms from its lattice site and can also generate gas in a material. Fission reactors are very high displacement rate with very low gas. Fast reactors produce 10 times more gas with a high displacement rate. 14 MeV neutrons, or fusion neutrons, produce copious amounts of gas but not as many displacements per atom. The same material scientists like to apply their skills across the field, in light water, fast reactor, and fusion applications. Fusion is important because it creates an energy source that costs almost nothing and that produces a waste which is helium gas. This technology is something that should be strived for.

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1 - Training for Navy Nuclear Submarines

Bret Kugelmass: What brought you into the nuclear space?

Larry Smith: Larry Smith’s first exposure to nuclear was in the Navy, where he became intrigued with submarines and became a part of the Navy Nuclear. His curiosity of history and World War II led him to the Naval Academy. At the Academy, he was exposed to ships, submarines, the Marines, and pilot school and ultimately chose submarine work. Smith found out his senior year that he was selected for nuclear power, which required interviews at the Naval reactors in D.C. before selection. Larry Smith spent five years active duty in the Navy, which included six months of nuclear training and six months prototype in Ballston Spa, NY where individuals would go on-shift at reactors and get qualified. Submarine officer basic school in Groton, CT was three months long and missile school in Dam Neck, VA since he was on a ballistic missile submarine. While at sea, Smith would serve with 150 guys for 90 days. 18-hour days consisted of shift or watch for 6 hours and the other 12 hours were spent catching up on personal work, doing drills to get proficient, or getting qualified. Smith became qualified engineering officer to watch, putting him in charge of the three people in the engine room. Qualified officer of the deck is in charge of the submarine when the commanding officer is not there and then goes through a review board to receive Dolphins. Submarine fuel is designed to handle quick changes in power levels.

2 - Engineering Roles at Calvert Cliffs

Bret Kugelmass: What civilian nuclear role did you decide to take on?

Larry Smith: After five years in the Navy, Larry Smith had decided he didn’t want anything to do with nuclear because of all the paperwork and red tape. He realized he missed the rigor and the discipline of the nuclear industry and decided to enter a civilian role at Calvert Cliffs as quality assurance. Smith was responsible for looking at engineering and making sure they were following requirements. His role progressed from quality assurance to engineering, starting out in design engineering and moved to license renewal. At this time in the late 90’s, the plant decided to pursue a license extension from 40 years to 60 years and Smith was asked to develop a thermal fatigue monitoring system for the plant. He then moved to core design where he learned how to deal with the codes and map the fuel to verify the right fuel is in the right location. The goal of moving the fuel around within the core is to get the most energy out of the fuel as possible; a third of the fuel is replaced every refueling outage and the other fuel is once burned fuel and twice burned fuel that is moved around. Smith then transitioned into procurement engineering where he focused on buying parts and doing equivalencies for obsolete parts. He didn’t want to be in just one aspect of engineering, instead wanting to get a rounded view of all aspects.

3 - Self-Regulation in the Nuclear Industry

Bret Kugelmass: What was the first management role you took on?

Larry Smith: Larry Smith’s first management role at Calvert Cliffs was as supervisor in systems engineering, transitioning to mechanical and civil engineering supervisor shortly thereafter to fill a need. The supervisor oversees the engineers’ work and research to make sure they are considering everything they should consider. The plant must meet the licensing requirements which were committed to the Nuclear Regulatory Commission (NRC). The nuclear industry needs to make sure processes and procedures are being followed to protect the health and safety of the public. At one point, Smith left the industry to do forensic engineering. He learned during that job that a lot of industries take out the safety functions available in equipment to make sure production goes up and to lower costs.

4 - Emergency Preparedness & Environmental Protection

Bret Kugelmass: How did you take your forensic engineering experiences and take them back into the nuclear industry?

Larry Smith: After Larry Smith’s time in forensic engineering, he realized that the nuclear industry was doing things right in keeping their workers and the public safe. Everybody has to wear their personal protective equipment (PPE) and the team focuses on understanding the why’s of behaviors and requirements. Smith is also in charge of emergency preparedness (EP) which entails making sure the plant can respond at any kind of event, such as a hurricane. The EP staff looks at if they need to have people staffed around the clock at different locations if something happens, such as a loss of off-site power or flooding. Smith supervises environmental folks at the plant as well. Calvert Cliffs has permits from the State of Maryland that must be met, including discharge, environmental stewardship, and equipment leaks. The local environmental community is very supportive of the plant and the staff works to make sure they understand what the plant is doing. The environmental group goes around to different groups on-site to make sure they understand what is required for environmental stewardship and that the correct protection measures are being taken.

5 - Nuclear Plant Drills and Inspections

Bret Kugelmass: What are the different levels of emergency preparedness?

Larry Smith: The Calvert Cliffs Power Plant interacts with the county agencies in Calvert County, Dorchester County, and St. Mary’s County. The plant works with the Maryland Department of Environment to do drills like there is an event and all the parties interact, which is sometimes observed by the Nuclear Regulatory Commission (NRC) and FEMA. During a drill, a simulator comes up with the drill and the data and different emergency response organizations, of which there are four on-site, get a drill each year. The scenarios encourage thinking outside the box to recover the plant or protect the health and safety of the public. There are also hostile action drills which cover a situation in which an armed force tries to attack the plant. Every power plant has a senior resident from the Nuclear Regulatory Commission (NRC) and a resident inspector on-site at all times. They are included in matrix notifications, which allows them to get into the details and see how the plant operates. Different inspectors come for various inspections during the year, but the residents have their own requirements for what they need to inspect. Having a good relationship with the NRC helps in regulatory margin and they are able to understand how things work. Larry Smith serves as station duty manager, which makes him responsible for an issue with the plant if it were to come up. Smith would get the engineering or maintenance support that the plant needed to address the issue. Nuclear energy is a clean source of power that operates all year round. The safety and the dedication of the people at a nuclear power plant helps provide as much energy as they do.

1 - Internship at Three Mile Island

Bret Kugelmass: How did you get into the nuclear space?

Dean Divittore: Dean Divittore grew up in Middletown, Pennsylvania, about three miles from Three Mile Island (TMI) Nuclear Power Plant. He got interested in nuclear power during high school and was selected as an intern for the team that owned Three Mile Island during the summer of 1983. Divittore was in 8th grade during the TMI 2 accident. When the accident happened, it was scary for the neighborhoods because they were not educated about nuclear power at the time. Following the accident, everyone was educated very well about nuclear power, the effects of radiation, and how the accident didn’t have that much effect on the environment. Divittore’s father worked in security at TMI at the time of the accident, but his family was more educated about nuclear than most families. During his internship, Divittore went through simple operations training to understand the plant and learn about each department in the plant. Three Mile Island Unit 1 was built first and TMI 2 was built after Unit 2 was already operating. They are both Babcock & Wilcox (B&W) pressurized water reactors (PWR’s). Divittore was offered a job at the plant right after graduating high school and went into radiation protection. He wanted to be involved in radiation protection to protect and educate people on-site and in the public.

2 - Radiation Protection

Bret Kugelmass: Would people who work inside a nuclear power plant receive less radiation than people who don’t work in a nuclear power plant?

Dean Divittore: In some cases, like in parts of the medical industry, people receive more radiation that workers at a nuclear power plant. Administrative limits at a nuclear power plant are set even lower than federal limits and workers don’t get much more than background radiation from other places, such as x-rays and cosmic radiation. Background radiation comes from naturally occurring things, such as uranium in the Earth and cosmic radiation from the sun. Radiation is an energy that affects cellular growth in the body, so the industry follows the LARA (low as reasonably achievable) principle so as to see no effects. Radiation cannot be seen, but can always be measured, similar to electricity. Radiation is measured using radiological instruments, such as the Geiger and ion chambers. Dean Divittore was a radiation protection technician for 14 years and a supervisor for four years. At Three Mile Island, he worked through the clean-up of Unit 2 and the outages for refueling the reactor. During an outage, a radiation protection tech supports the maintenance and operations and focuses on protecting people from radiation sources. Different areas of a plant have different levels of radiation, such as the auxiliary building which has all the supporting systems for the reactor core which has primary water going through them and therefore is radioactive. The turbine building has no reactivity in it. A pressurized water reactor (PWR) has a bioshield; concrete shields the reactor, steam generators, and recirc pumps so that the people working around those areas are shielded by the radiation sources. The radiation sources are the fuel, where it originates, steam generators, recirc pumps, and piping inside the containment building.

3 - How Water Shields Radioactivity

Bret Kugelmass: How do radioactive sources move through water and how is the water arranged to act as a shielding source?

Dean Divittore: Water is a neutron moderator. When the reactor is operating, the neutrons are absorbed in the water and the water also acts as a shield. The gamma radiation, high energy N16 gamma, is formed as part of the reaction between the neutron and water. It has a half-life in milliseconds, so when the reactor is shut down for a refueling outage, all the N16 gammas are gone within seconds. Other radioactive isotopes include cobalt-58, cobalt-60, cesium, and transuranic fuel, if there is a defect in the fuel. A fuel defect is when a fuel pin may have a defect in it that lets gases escape from the fuel pellet. This is found through chemistry sampling and gases rising in the reactor coolant system. Reactor engineers cannot determine which specific pin has a defect, but they can determine whether it is a first, second, or third burn assembly and whether it is on the outer or inner area of the core. The whole assembly may be removed from the core or the pin may be removed, reconstructed, an re-inserted.

4 - Radioactivity in the Containment Building

Bret Kugelmass: What’s a hot spot and how do they form within a controlled environment?

Dean Divittore: The most common hot spot forms in low flow areas where corrosion builds up, creating cobalt-58 or cobalt-60. The area will get signage to identify the hot spot location and it is mitigated through shielding and flushing. Shielding, such as with a lead blanket, could be used until it is able to be flushed. Hot spots are flushed with hydrolasers during shutdowns. When people need to go inside the containment building, they will get a briefing about the expected conditions. A radiation protection technician will accompany them into containment and they wear a protective suit for contamination. Contamination is when the radioactivity escapes the system, maybe from a small leak in a valve, becomes airborne, and settles on the floor. After being a radiation protection supervisor at Three Mile Island (TMI), Dean Divittore went into work management where he scheduled and planned work as the plant was online and through outages. Divittore also worked for nuclear oversight, went back into radiation protection as a radiological engineering, became the radiological engineering manager, and then the radiation protection manager. He was responsible for all the programs in radiation protection, including field operations, technical support, and radiological engineering. Some challenges of the job include how to do some portions of the work, including leak identification inside the containment unit during operation with the use of robots, cameras, and drones.

5 - Innovation’s Impact on Radiation Protection

Bret Kugelmass: Are there other radiation protection management techniques or mechanisms?

Dean Divittore: The fleet has an innovation team that came up with a new way to survey things in the plant. Live cameras all over the plant allow people to see what’s going on in other areas, such as the auxiliary building. The innovation team combined best practices from all the sites to create one program that all sites now use. Touch screens bring up a map of the plant and plots radiation across different areas. The plant also has a 360-degree scanned image of different areas, which are useful for planning work. Other smart procedures include a radiation protection technician taking out their procedure for an air sample on an iPad, input the sample readings, and the program will calculate the air activity. This process saves time and saves dose for the individual. The energy level of a gamma ray determines at what distance the ray drops off and the level of shielding required. The distance at which a person is safe is also dependent on the geometry of the ray source.

6 - Benefits of Nuclear Power

Bret Kugelmass: How did you end up at Calvert Cliffs?

Dean Divittore: Dean Divittore served as radiation protection manager (RPM) at Three Mile Island for eight years and was ready for something new, leading him to another site in Exelon’s fleet, Calvert Cliffs. Calvert Cliffs is more challenging because there are two units, compared to Three Mile Island’s single unit in operation. Three Mile Island Unit 1 is due to be shut down in October 2019, but they are looking at legislature that could help them stay open. Divitorre considers himself an advocate for nuclear power. Nuclear plants bring very stable power to the grid, compared to other energy sources that may fluctuate a lot. It’s important for people to have power and shutting down nuclear power plants could have impacts on your access to power.

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.

1 - Profile of a Navy Nuclear Electrician

Bret Kugelmass: What was it like growing up in New Jersey?

Nicholas Cahill: Nicholas Cahill grew up in a densely populated area in New Jersey where all the towns connected to each other with no gaps in between. He had an interest in computer science in middle and high school, leading him to join the Navy to learn more about computer science. Once in, he realized there were multiple fields he could go into related to computer science and he was offered an opportunity to work in the nuclear part of the Navy. Cahill had to take the ASVAB test when he entered the Navy which decided which jobs he would qualify for. The nuclear field has multiple rates, such as an electrician, an electronics technician, or a mechanics; Cahill became an electrician. Navy technology was a little dated, but was a tried and true reliable analog system. Cahill served on the U.S.S. Louisiana ballistic missile submarine out of King’s Bay, Georgia. As an electrician on a six-hour watch, he would monitor equipment and listen for early signs of failure or look for temperature indications. This included continuous monitoring of electrical power production and shifting the plant operations around for maintenance. The six-hour watch shift was followed by a six-hour maintenance shift and a six-hour sleep shift before starting the next 18-hour day.

2 - Criticality Analysis of Fuel Storage

Bret Kugelmass: Why did you decide to stay in nuclear after spending nine years in the Navy?

Nicholas Cahill: After spending nine years in the nuclear Navy, Nicholas Cahill became an advocate for the technology as he learned more about its carbon-free impact on climate change. Nuclear energy is the safest energy production method due to its energy density and the actual repercussions of minor issues on-site are low impact. While in the Navy, Cahill spent three years in upstate New York teaching nuclear operators in the Navy how to operate a fully functional nuclear engine room. He taught them how to work, stand watch, and make trends. In parallel with his job function with the Navy, Cahill got to attend Rensselaer Polytechnic Institute (RPI) where he received his nuclear engineering degree. An opportunity came out with Constellation Energy and Cahill transitioned from a Navy operator into a civilian nuclear engineer. His duties were split between reactor engineering and fuel or safety analysis. Criticality analysis looks as the process of getting the fuel assembly from the new fuel storage area to spent fuel and back into the core. In the original spent fuel pool, fuel was separated by more space to avoid criticality. More fuels can pack closer together is neutron absorbers, such as boron, are placed in between and in the water. He works with a lot of software tools to assist with criticality analysis of fuel storage and they make sure he is executing safe actions.

3 - How Reactor Engineers Support Operations

Bret Kugelmass: How did you switch from the Constellation group to the Exelon group?

Nicholas Cahill: Constellation Energy merged with Exelon, becoming the largest nuclear generation company in the nation. Nicholas Cahill stayed at Calvert Cliffs during the transition. He pulled more out of the safety analysis side, doing less design-type work in reactor engineering and now more operational support, such as moving fuel and maneuvering power levels. Certain plants in the industry will have to change power to follow load based on the economics of electrical energy production. Calvert Cliffs may maneuver power for maintenance items, which could be planned or caused by unexpected conditions related to the Chesapeake Bay. A reactor engineer helps the plant move through the maintenance evolution, specifically what is going on in the core. They may tell the operators how to maneuver the plant in certain control rods or diluting the reactor coolant system to change power, while keeping an eye on peaking factors. Operations has surveillances performed based on technical specifications which specify the frequency between surveillances, depending on the parameter. Some parameters monitored are core tilt and axial shape index. Reactor engineers make sure the plant is not producing too much power in one portion of the core based on technical specifications.

4 - Maintaining Reactor Power and Water Chemistry

Bret Kugelmass: What’s the process of receiving data on power production and making adjustments?

Nicholas Cahill: Boiling water reactors (BWR’s) are able to insert individual control rods which come up from the bottom, compared to pressurized water reactors (PWR’s) like at Calvert Cliffs in which control rods come into the top. BWR’s have more of a challenge in shaping their power. Calvert Cliffs will typically run with all of the control rods out so it doesn’t have to be shaped as much. Reactivity is controlled with boron in the water; the amount of boron can be reduced by putting neutron absorber in the fuel itself. When the plant is operating at 100% power, which is normal operation at Calvert Cliffs, a boron level is maintained. As nuclear fuel is burned out, the boron is diluted with water to bring power back up. The rate that fuel burns is pretty constant, but the changing in boron depends on burning of neutron absorbers as well. Minimizing the water put into the core is important because it becomes wastewater that has to be cleaned up and takes multiple steps to process. Nicholas Cahill participates in a reactivity management program which looks at issues on-site and opportunities to improve either the procedure process or human performance. This is used to identify what challenges the plant is having. He is also part of an industry working group that has multiple different technologies from the PWR world and shares issues and improvements. Cahill advocates for nuclear energy, and science in general, in the community by going around to schools to promote STEM education.

5 - Carbon-Free Base Load Power

Bret Kugelmass: Why is nuclear energy important?

Nicholas Cahill: Nuclear energy is one of the safest ways to have a base load generator. The country is bridging from being a heavy carbon producing electricity generator to having carbon-free and sustainable energy sources, nuclear is the base load energy producer needed to make it to the future of sustainable energy. Exelon has a huge part in solar, wind, and geothermal power as well, but nuclear energy will be the base load for the meantime.

1 - Mechanical Engineering on Submarine Builds

Bret Kugelmass: Where did you grow up?

Kevin Dougherty: Kevin Dougherty was born in Maryland and grew up all along the East Coast. His high school physics teacher recognized his talent for mechanical things and pushed him towards engineering. Dougherty received his mechanical engineering degree at Rensselaer Polytechnic Institute (RPI) in upstate New York. While he didn’t have any interaction with the nuclear program or nuclear engineering students at RPI, Dougherty took a job offer from Electric Boat, a submarine builder for the Navy. He started out working as a mechanical engineer on heat exchangers in the early 2000’s in Groton, Connecticut. Later, Dougherty got recruited into the shift test engineer program, which made him the responsible individual qualified on all the nuclear aspects of the submarine during a build. He spent two years in class to learn everything about the nuclear side of the submarine. Dougherty worked on the build for the first Virginia-class submarine, which involved a lot of growing pains.

2 - System Engineering at Calvert Cliffs

Bret Kugelmass: How are submarines built?

Kevin Dougherty: Submarine builds start in the warehouse, where a lot of the testing happens, including making the reactor critical. It is then placed into a dry dock, eventually flooded with water, and floated away. When a reactor goes critical for the first time, engineers verify that the predicted design calculations meet what is being seen in the field. Power levels are watched and when temperature changes, the reactor power should change appropriately. Kevin Dougherty worked for Electric Boat in Groton, CT from 2001 to 2007. At that time, he got transferred to the Naval Yard in Washington, D.C. where all the design engineers for the Navy work. Doughtery acted as a liaison between people back at Electric Boat and the people in the Navy. He liked the industrial side of the work more than the office side, so around 2007, Kevin Dougherty applied to be an engineer at Calvert Cliffs in system engineering, which is now strategic engineering. His responsibility was to own one of the systems on the plant and make sure it is healthy and working properly. The three main systems are primary systems, which touch the reactor, secondary systems, which are generation or cooling specific, and electrical subsystems. Dougherty had prior primary systems experience from being a shift test engineer at Electric Boat, so he chose primary systems and he owned the reactor coolant system for three and a half years. A lot of the reactor coolant system management is outage planning and potential design improvements. Dougherty spent a lot of time digging into the root cause of relief valve failure. The Part 21 process through the Institute of Nuclear Power Operators (INPO) and the Nuclear Regulatory Commission (NRC) is used to share known issues throughout the industry.

3 - Calvert Cliffs Plant Operation

Bret Kugelmass: How does an operating system going outside the normal operation?

Kevin Dougherty: For a reactor coolant system (RCS), the goal is to never have the system go outside the normal operating pressures. There is one normal system in which it would open, which is if the grid power goes down. The RCS is pressurized at all times and the steam side, which goes to the turbine and condensers, is where most of the energy is released. Two different automated systems relieve that energy on a planned trip: turbine bypass valves, which bypass the turbine and put steam straight into the condenser, and atmospheric dump valves, which relieve pressure straight to the atmosphere. Main steam safety valves can also relieve full power if needed during an unexpected accident situation. Kevin Dougherty got his MBA from Georgetown during his time at Calvert Cliffs. He currently serves as a shift manager. He was recruited into a two-and-a-half year class to become a licensed operator eight years ago. Operators need to know what all the switches and indicators in the control mean and understand the impacts of any action taken. Dougherty got qualified to be a senior reactor operator (SRO), which is one of the control room supervisors. The integrated plant knowledge of how everything affects each other was mind-blowing to Dougherty. He also learned how sensitive the plant is to the non-nuclear environmental side of things. The plant cares about the wildlife on-site and impacts to the Chesapeake Bay.

4 - Execution of a Reactor Outage

Bret Kugelmass: Tell me about the relationship between the environment and the plant.

Kevin Dougherty: Calvert Cliffs is a good environmental neighbor. As a shift manager and leader, Kevin Dougherty puts the message out to the site that the team cares about the environment and people around them. He wants his people to be ready to go and have a good questioning attitude, but not be robots. Their head has to be one hundred percent on task, because the consequences of not being focused in nuclear power are big. Calvert Cliffs does one outage a year; each unit comes down once every two years to refuel. The outages range from 20-30 day process depending on how much maintenance is being done. These maintenance operations are usually big capital improvements to extend the life of the plant, such as upgrading turbine blades or installing a new digital control system. A lot of inspections are also done on equipment during outages, as well as pump replacements. During an outage, Kevin Dougherty stands shift manager, but his first role is nuclear safety. The focus is on keeping the workers safe, keeping the plant safe, and keeping the public around the plant safe. The plant is maneuvered around to make sure maintenance technicians can go in to repair or replace things.

5 - Daily Operations at Calvert Cliffs

Bret Kugelmass: Is there a stand-up at the beginning of the shift during an outage?

Kevin Dougherty: Every day, Kevin Dougherty does a morning briefing with the site where all the managers across the site are in one room to get everyone aligned on priorities and operations. Managers then go to their people to communicate the plan for the day and make sure everyone is focused. During the outage, the morning meeting is similar, but more stressful. Calvert Cliffs is on 12-hour shifts and Dougherty works a rotating day/night schedule on a five week cycle. During shift turnover, an official checklist is completed and shift managers pass on informal turnover notes that go to all shift managers. Every shift, a leadership report is also completed to evaluate how a team is performing from a holistic standpoint, not just technically. Supervisors go to the field to help their teams, but also observing for behaviors wanted in the field. The nuclear industry was ahead in terms of organizational rigor due to the potential consequences. The Institute of Nuclear Power Operators (INPO) was formed after the Three Mile Island accident. INPO was set up so that the best practices from 100 nuclear power plants could be shared with each other, even with competing companies. INPO has accelerated nuclear performance to get to a place of organizational rigor. Kevin Dougherty received his MBA from Georgetown a couple years ago, a degree he pursued out of curiosity to understand more than just the technical side of nuclear power. He has been able to share the financial side of why decisions are made with his team and how it ties into the day-to-day operation.

6 - Decision-Making as a Team

Bret Kugelmass: In your time at Calvert Cliffs, have there been problems that came up that the team had to put their heads together to solve?

Kevin Dougherty: Earlier this year, Calvert Cliffs had an electrical subsystem which was getting intermittent grounds on one of the DC buses. The team was able to narrow it to one of transformers which helps put power down the line. The decision-making process to either isolate the ground or leave the ground in required input from a lot of different people. They were 99.9% sure what would happen if they isolated that ground, but there was a 0.1% chance that they were wrong and something would potentially trip off. The consequences of the ground getting worse were greater than the 0.1% change of tripping something. A 15-page document was written detailing the decision-making process. The ground came back in the middle of the night while Kevin Dougherty was training a new shift manager. The pre-work done ahead of time prepared this new manager to make the decision easily. Dougherty is very proud of the work done at Calvert Cliffs. They are currently focusing on how to decrease cost while maintaining operational and safety excellence to ensure long-term operation.