Exelon goes first with PBMR

“Okay, We’ll go first.” I heard Exelon’s new advertising slogan for the first time on February 1, 2001. I felt the secret thrill that comes from recognizing an allusion that one is pretty sure very few people “get”. I had a strong desire to say “Yeah” and pump my fist.

You see, I had just attended a meeting at which Exelon employees had taken the first official step in the process of becoming the first company to build a new nuclear power plant in the United States in several decades. On Wednesday, January 31, at a public meeting held in a cramped conference room, Exelon gave a focused presentation to the NRC to discuss their plan for licensing the Pebble Bed Modular Reactor, a 110 MWe plant that has been designed by a team led by Eskom, the South African utility.

Though the leader of the project was careful to state that Exelon has not made the final decision to build a power plant, the speakers made it clear that the project would proceed unless there is a fundamental design flaw found during the next eight months. They also provided the audience with a clue about why this project was different from other design efforts during the past ten years that had not successfully led to new construction in the United States.

Here are some basic facts about the PBMR that make it significantly different from previous designs. In fact, the characteristics of the plant are so different from conventional nuclear plants that the machine qualifies as the “new new thing” in the vocabulary of high tech investors.

The PBMR is a 110 MWe closed cycle gas turbine. The coolant and working fluid is inert helium. The plant is designed to be continuously refueled, eliminating the need for periodic shutdowns except for equipment maintenance. With a clean, chemically inert working fluid, the projected maintenance interval is about six years.

The fuel elements closely resemble the eight ball in a game of billiards; they are the same size, shape and color, but they are not a shiny and do not have a number painted on them. These deceptively simple balls conceal the key to this revolutionary machine.

Inside the balls is a fuel structure that allows them to withstand temperatures in excess of 1600 degrees Celsius without releasing any fission products and temperatures in excess of 2500 degrees Celsius without structural failure. (Detailed design information about the fuel can be found at www.pbmr.co.za.)

With their high temperature capability, the balls (AKA pebbles) not only allow a gas turbine heat engine to replace a more complex and less efficient steam plant, but they also enable the PBMR team to stand behind a claim they have designed an inherently safe plant that cannot release dangerous radiation to the environment no matter what unplanned events occur.

Through actual physical tests, rather than computer simulations, the project leaders plan to prove that their machine can withstand a complete loss of cooling without a reactor scram and without any action on the part of an operator or an automatic system to restore cooling.

That is a revolutionary assertion that will enable serious cost reduction by eliminating a lot of complex systems and components. Exelon counts about 40 systems in this design compared to more than 120 for a “simplified” pressurized water design.

There will also be costs saved in site planning; Exelon and her partners state that the planning zone around the reactor will be 400 meters. Beyond that range, there will be no need for emergency response team involvement or to plan evacuation routes. Exelon already owns a number of sites large enough to contain that kind of planning zone without involving any neighbors.

The staff of a PBMR will more closely resemble the staff of a conventional gas turbine than it will the staff of an existing nuclear plant. The legions of engineers constantly redesigning and relicensing the plant will be gone as will a large number of people needed to operate and maintain the steam plant, the emergency systems and to coordinate with local governments. The refueling planners will likewise be replaced by a small cadre of people who work on the continuous refueling system.

Unlike the Integral Fast Reactor, the Advanced Boiling Water Reactor, the PIUS, and the AP-600, all of which were solid nuclear plant designs that never found a market, the PBMR has been designed from the beginning by a company that wants what a well designed nuclear reactor can produce, i.e. cost-effective power. Exelon made it quite clear that they intend to build this as a “merchant” power plant. For those not conversant with the lingo, that means that they do not intend to put this plant into the rate base, they intend to take the risk that their costs will be repaid by selling power at the market price. My analysis tells me that they have the potential for a financial home run on their hands.

At both Eskom and Exelon the project has an identifiable leader with a history of success. Both leaders developed their nuclear and leadership skills underwater. Eskom’s PBMR point man is David Nicholls, a former British submarine commanding officer while Exelon’s CEO is Corbin McNeill, a 1962 graduate of the U. S. Naval Academy and the former Commanding Officer of the USS Tautog SSN 639, a Sturgeon class submarine.

It was refreshing to hear employees of an electric company speak of their CEO in the kind of language normally used for an entrepreneur like Bill Gates. When discussing the aggressive, but achievable schedule for licensing and building PBMR’s, the presenters at the meeting told everyone that they were learning to operate on “Corbin time” and that “Corbin would have preferred” an even shorter path to completion.

I have a great deal of optimism for the eventual success of this project. All the ingredients are there for a system that has a revolutionary impact on a major industry.