1 - 01:25

Q: Why did you enter the field of chemical engineering?

A: Marilyn Kray grew up in Pittsburgh and received her bachelor’s degree of chemical engineering at Carnegie Mellon University. Kray originally thought she would enter the oil and gas industry, but the oil crisis happened while she was in school. After graduation in 1983, she joined the Nuclear Regulatory Commission (NRC), which was in the post-Three Mile Island accident recovery phase. Exelon’s biggest representation of technical experience is in mechanical and electrical engineering, following by chemical engineering, then nuclear engineering. All systems must work together in the plant to provide power generation.

2 - 06:00

Q: What were some of your first jobs at the Nuclear Regulatory Commission (NRC)?

A: Marilyn Kray’s first project at the Nuclear Regulatory Commission (NRC) was Beaver Valley, located outside of Pittsburgh, which was originally owned and operated by Duquesne Light. Kray started out working at the NRC headquarters out of Washington, D.C. and reviewed design, calculations, and supporting analyses. Kray then moved to NRC’s Region 1 Northeast office to inspect the physical construction to verify it is being built according to the approved design. As a region-based inspection, Kray traveled to all different plants within the region and performed specialty inspections, as opposed to a resident inspector which reports to one specific power plant. After five years at the NRC, Kray joined Philadelphia Electric (PECO), a predecessor company to Exelon, during the Peach Bottom outage.

3 - 11:34

Q: What kind of power plant is Peach Bottom?

A: Marilyn Kray joined the recovery team at Peach Bottom, a boiling water reactor that came online in the mid-1970’s. The role of the recovery team was to determine what was needed to get the plant started up again, by overcoming physical and cultural issues. Today’s industry has more of a respectful appreciation of the regulators, as they share common goals, but at the time that Kray joined, the industry had a more negative view of the regulator. Kray became involved in the refueling outage approach, when efficient refueling outages did not exist. Outage duration must be minimized due to lost income from power generation and increased cost of additional personnel and organization on-site. Kray was able to improve outage duration from 60 days down to 30 days. PECO had a joint venture with British Energy, at a time in which plants were decommissioning and some plants had many more years of life left than the NRC would allow. The joint venture purchased Three Mile Island Unit 1, the non-accident unit, Clinton Power Station, and Oyster Creek.

4 - 22:43

Q: As the markets and businesses changed around nuclear, what roles did you take on?

A: As the nuclear markets and businesses changed, Marilyn Kray took part in non-traditional nuclear roles. Kray took part in AmerGen; if the nuclear plants had not been purchased at the right price, they would have been shut down. Kray also worked with Entergy and started a joint venture called New Start Energy Development, which was a consortium of plants looking to license the existing fleet. A new process with the Nuclear Regulatory Commission (NRC) changed the way plants were licensed. Part 50, original licensing procedure, requires information about plant to be built provided to the NRC, which approves building to start but allows changes to be made during the construction process. This optimizes the balance between flexibility and certainty, however one risk is getting an approved design to build, but not being able to provide an approved emergency plan to receive the license, which happened at Shoreham Nuclear Plant. Part 52, a combined construction and operational license, requires a lot more information submitted to NRC before allowed to start construction, which expedities construction if what was requested is built, but changes coming from the design team are more difficult and time consuming to get approved through NRC.

5 - 33:33

Q: How do nuclear education efforts go towards other utilities?

A: Marilyn Kray sees opportunities with smaller-scale nuclear plants to be run by utilities that do not have existing experience with nuclear plants. Small modular reactors (SMR’s) can be sited at many different places and operators trained more quickly. Some customers look for Exelon to operate these nuclear plants temporarily or indefinitely or to bridge the gap for the customer to ultimately operate on their own by embedding teams and completing additional cultural training focused on safety and decision-making. This provides a holistic view to plant operation. Exelon is able to provide subject matter experts and an atmosphere in which information and lessons learned are shared.

6 - 40:20

Q: What is your matrix of evaluation for new nuclear designs and how do you rate them internally?

A: Technology readiness and maintainability are two main factors that Marilyn Kray and her team at Exelon when considering and evaluating new nuclear designs. Access within the plant for refueling and replacing equipment can have a significant impact on maintainability. Most vendors have advisory boards that actively seek feedback from Exelon and other utilities during the design phase to integrate lessons learned. NuScale, Holtec, and General Electric Hitachi are among some of the projects pursuing light water small modular reactors (SMR’s). The main competition for this technology is combined-cycle power, not other nuclear plants. Funding for SMR’s could open possibilities for single investors to buy the output power from the plant, as opposed to traditionally entering a regulated market in which a public utility purchases the output power. Marilyn Kray is preparing to serve as President for the American Nuclear Society (ANS).

7 - 50:43

Q: Why is nuclear technology so important?

A: Marilyn Kray sees a global need for electricity, and nuclear is a resource that can be used in a safe manner in a way that is complementary to other utilities. Nuclear takes the lead with respect to reliability and environmental benefits, while other utilities may take the lead with respect to cost and other factors.

7-10 Bullets
- How different engineering disciplines collaborate to make a nuclear plant operate - Role of the Nuclear Regulatory Commission during design and construction of nuclear plants - How the culture between utilities and regulators in the nuclear industry has evolved over time - What it takes to prepare and execute a nuclear plant refueling outage plan - Licensing options for existing and newly designed nuclear plants during design, construction, and operation - How traditional utilities and investors are getting involved with new nuclear technology - Education efforts supported and funded by the American Nuclear Society