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Atomic Insights

Atomic energy technology, politics, and perceptions from a nuclear energy insider who served as a US nuclear submarine engineer officer

Pebble Bed Reactors

Atomic Show #287 – Darren Gale, VP Commercial Operations, X-Energy talks about Xe-100

November 12, 2020 By Rod Adams 2 Comments

X-Energy is the lead recipient for one of two industry groups selected to receive $80 M in Department of Energy (DOE) funding as part of a public-private partnership program to demonstrate advanced nuclear power plants on an aggressive time table.

Its primary partner in the endeavor is Energy Northwest, which currently owns and operates the Columbia Generating Station in eastern Washington. Energy Northwest will be the owner and operator of the demonstration power station, which will consist of a four-unit installation of X-Energy’s Xe-100 high temperature gas cooled reactor.

Each unit is designed to produce 80 MWe, resulting in a power station output of 320 MWe.

Advanced Reactor Demonstration Program

The award is part of the Advanced Reactor Demonstration Program, which also includes two additional development pathways with longer horizons. The $80 M in FY 2021 funds is a down payment that will provide funds for completing detailed design work and beginning the licensing process.

Future appropriations will be required to complete the projects; the funding opportunity announcement for the program included an award ceiling of $4 B to be shared among three different development pathways.

For Atomic Show #287, I spoke with Darren Gale, X-Energy’s Vice President for Commercial Operations. Darren is the company executive with direct responsibility for executing the company’s contract with the Department of Energy and delivering on the promise to design, license and construct an advanced nuclear reactor power plant.

The ADRP has an aggressive target date for beginning to deliver electricity to the grid is the end of 2027. During our conversation, Darren explained how his company is positioned to deliver on its promise.

Xe-100 Design history

We spoke about how X-Energy has been working on its high temperature pebble bed reactor design for more than a decade. X-Energy was founded in 2009 by Kam Ghaffarian, a successful entrepreneur who founded Stinger Ghaffarian Technologies (SGT) in 1984. Dr. Ghaffarian remains the owner of X-Energy, but is being joined by additional investors.

The design is mature and the company has been engaging with the NRC for several years. It expects to be able to submit a license application within the next year or two; part of the uncertainty includes determining the most appropriate and streamlined licensing pathway.

The Xe-100 is a helium-cooled, high temperature pebble bed reactor that has a number of similarities to the Chinese HTR-PM. They share a common heritage tracing back through the South African HTGR program and to the German AVR demonstration reactor.

As Darren explains, the Xe-100 includes a number of refinements in its fuel design and in its fuel handling system that enable more efficient fuel use.

Another design difference is that each Xe-100 reactor/steam generator modules are connected to its own Rankine cycle steam turbine. In the HTR-PM design, two reactor/steam generator modules feed a single larger turbine.

The 80 MWe power output selection was influenced, in part, by the availability of off-the-shelf steam turbine power plants. Unlike light water reactors, the Xe-100 will produce steam at temperatures (565 ℃) and pressures (16.5 MPa) used in modern supercritical steam systems.

Like the HTR-PM, Xe-100 reactors are continuously fueled while operating, eliminating the need to schedule refueling outages. There will still be a need to periodically shut down the reactor for inspections and steam turbine maintenance. X-Energy expects that there will be more requirements during the early years of operation while the company and the regulator gain experience and understanding of operational effects.

Eventually, though, the company expects to achieve somewhat higher than average availability than conventional reactors that require unavoidable outages for refueling.

Project location

The project will be built in eastern Washington at WNP-1, a site that was licensed for construction of a nuclear power plant in 1975. Using a site that has already been reviewed and approved for use as a nuclear plant greatly reduces the amount of time and effort required for long lead time environmental impact reviews, seismic surveys, and site pre construction surveys.

Though the original plant was never completed, certain civil structures, including a water intake system and pump house were completed before the project was cancelled. Darren explained that the existing infrastructure at the site would require refurbishment, but it enables a more rapid timeline than a greenfield.

Employment opportunities

X-Energy is in the hiring mode. The Xe-100 team head count is approximately 50. Some of the necessary tasks will be completed by contractors. But Darren expects that the permanent team will expand to include 200 or more people within the next year or two.

Most of the project design work is taking place at X-Energy’s Rockville headquarters, but current restrictions related to COVID-19 have required some creative uses of remote work, multiple buildings, and video conferencing. As a result of the learning that has come with that experience, X-Energy will be somewhat flexible in allowing some employees with key skills to work from remote locations.

The Xe-100 demonstration project is an exciting opportunity for advanced reactor designers and supporters to turn ideas and concepts into functioning equipment that generates real power and heat.

I hope you enjoy this episode and participate in the comment threads, especially if you have questions that are not addressed. As you will hear towards the end of the show, Darren expects to be able to return several times during the course of the construction project.

https://s3.amazonaws.com/AtomicShowFiles/atomic_20201111_287.mp3

Podcast: Play in new window | Download (Duration: 40:19 — 46.3MB)

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Filed Under: Advanced Atomic Technologies, Gas Cooled Reactors, Graphite Moderated Reactors, New Nuclear, Pebble Bed Reactors, Podcast, Small Nuclear Power Plants

Turning nuclear into a fuel dominated business

October 28, 2018 By Rod Adams 66 Comments

Cross section of TRISO fuel particle
TRISO particle – 1 mm diameter

Under our current energy paradigm, nuclear power has the reputation of needing enormous up-front capital investments. Once those investments have been made and the plants are complete, the payoff is that they have low recurring fuel costs.

Just the opposite is said of simple cycle natural gas fired combustion turbines. They require a small capital investment that can be paid off even if the plant only operates a few hundred hours per year. They don’t have an optimized fuel efficiency and they burn a fuel that can be quite expensive during the hours when the “peakers” need to run.

Those peakers are responsive and are becoming more interesting to power producers with the continued growth In variable renewable energy sources like wind and solar.

Just thinking out loud here, but what if it was possible to build really simple, much lower cost nuclear plants on the condition that they have a safety case that is built around a fuel design that is several times more pricey than conventional commercial nuclear fuel?

For more than 50 years, scientists and engineers have been working on coated particle fuels where tiny particles of fissile material in various chemical forms is surrounded by tightly adherent and durable layers of material capable of withstanding very high temperatures without releasing fission products.

In the space program, incredibly powerful and energy dense reactors have been designed and tested using coated particle fuels, but for commercial power generation, the usual path is to create large low power density reactors that are considered to be “inherently safe” because they don’t need any active cooling systems to prevent the core temperatures from exceeding the much more generous limits allowed by high temperature fuel.

Unfortunately, the development of reactors using coated particle fuels has been held back by a couple of technical choices. One has been that the reactors have been seen as a modest improvement in conventional reactors that still need to have most of the expensive equipment of a steam plant power conversion system.

Using that heat engine choice, designers must include heat exchangers that are functionally equivalent to the high cost steam generators in pressurized water reactors. Since they need heat exchangers, they naturally look toward high gas pressures in the primary coolant loop in order to increase heat transfer rates.

That path leads to systems with capital costs that are not much different from conventional nuclear plants with the added burden of using fuel that is quite a bit more expensive, especially in the early years before the manufacturing lines become cost efficient.

General Atomics achieved initial marketing success with a line of GW class high temperature reactors (HTRs) in the late 1960s and early 1970s by emphasizing that their systems were somewhat simpler and used more conventional steam turbines than the lower temperature light water reactors. They inked about 10 contracts, but none of the plants were ever built.

X-energy, URENCO and HTR-PM all are pursuing updated versions of similar designs. They are not radically reconsidering the paradigm.

It’s possible to dig back into nuclear history and find that the HTRE (high temperature reactor experiment) used modified jet engines that sucked in atmospheric air, heated it in a modestly high temperature reactor (far lower temps than coated particle fuels enable today) and exhausted that air through a turbine and jet expansion system.

The capital cost of equipment for such an air breathing system today would be quite low, but there would likely be a problem with creating and emitting Ar-41 as well as the possibility that fuel manufacturing defects might allow some small quantity of fission products to be discharged. Regulatory hurdles prevent that path from being developed anytime soon.

With a modest increase in complexity and capital equipment, a mechanically identical system could use nitrogen gas separated from air. Because the gas isn’t air, it would need a closed system where a low pressure, moderate temperature heat exchanger performs the function of returning turbine exhaust back to atmospheric conditions for injection into the compressor.

This ultimately simple Brayton Cycle gas turbine would use fuel that might cost several times more per unit of heavy metal than conventional nuclear plants, but its initial investment should approach the cost of the combustion turbines that would be the heart of the system. Sure, there are costs associated with the piping systems, but those would likely be on a similar order of magnitude as the fossil fuel system pipes that would not be needed.

With dramatically lower capital costs and higher fuel costs, the total system cost allotment would be a complete departure from the conventional nuclear paradigm. No longer would equipment suppliers and financial providers be able to capture 50-75% of the total revenues, with personnel costs capturing 30-40% and the fuel supplier pulling up the rear with 5-20% of the revenue. Instead, financial costs could be far lower. Equipment costs would drop dramatically. Personnel costs per unit of output would fall.

The obvious result is that the fuel suppliers, the people who produce the fuel that is so capable that it is the safety case and safety boundary, would gain the lion’s share of revenue from product sales.

That situation has proven itself in the energy market. Customers and other stakeholders don’t necessarily like the fact that fuels people walk off with most of the money, but it has meant that fuel suppliers have adequate capital to both invest in new technologies and adequate incentives to promote the benefits of high energy use.

There is a massive amount of capital in the hydrocarbon fuel business. There is also a great deal of intellectual capital, some of which is scientific and technical, but some of which is business development and marketing.

In the early days of nuclear energy, the hydrocarbon giants dipped their toes in the business. They couldn’t figure out how to make as much money in nuclear as they were used to making, so they quickly exited.

Perhaps this early Sunday morning essay will help stimulate them to reconsider their decision to abandon the business without figuring out how to make it a fuels business that could answer a lot of their future challenges.

Note: I have more details about the paradigm shift described above, but I think I’ll hold them closely for now.

Filed Under: Adams Engines, Advanced Atomic Technologies, Business of atomic energy, Economics, Gas Cooled Reactors, Graphite Moderated Reactors, Pebble Bed Reactors, Smaller reactors

Fission heated gas turbines address MIT Future of Nuclear challenges. Easier, straighter, less costly path

September 20, 2018 By Rod Adams 57 Comments

Addressing Recommendations of MIT Future of Nuclear Energy In a Carbon Constrained World The Massachusetts Institute of Technology (MIT) is a world renowned institution that has produced thousands of highly educated engineers and scientists. It is generously supported by foundations, corporations and governments. In 2003, the MIT Energy Initiative, began publishing a series of reports […]

Filed Under: Advanced Atomic Technologies, Gas Cooled Reactors, Graphite Moderated Reactors, New Nuclear, Pebble Bed Reactors, Small Nuclear Power Plants, Smaller reactors

History and promise of high temperature gas cooled reactors

January 16, 2017 By Guest Author

By: Diarmuid Foley A small modular nuclear reactor to replace coal plants could be on the market within 5 years. In 2014, the Generation IV international forum[1] confirmed the Very High Temperature Reactor (VHTR) as one of 6 promising reactor technologies that should be pursued in order to develop advanced reactors suitable for deployment in […]

Filed Under: Advanced Atomic Technologies, Atomic history, Gas Cooled Reactors, Pebble Bed Reactors, Reactors, Small Nuclear Power Plants, Smaller reactors

Will China convert existing coal plants to nuclear using HTR-PM reactors?

November 21, 2016 By Rod Adams

It would be a huge benefit to the earth’s atmosphere if China, India, Brazil and the US could reduce direct coal burning while still making use of much of the capital that they have invested in building coal fired power plants. It would make an even larger difference in reducing air pollution in the areas […]

Filed Under: Advanced Atomic Technologies, ANS Winter 2016, Climate change, Gas Cooled Reactors, Graphite Moderated Reactors, New Nuclear, Pebble Bed Reactors

Atomic Show #248 – Dr. Pete Pappano, VP Fuel Production X-Energy

November 20, 2015 By Rod Adams 2 Comments

On Thursday, November 19, 2015, I interviewed Dr. Pete Pappano, vice president of fuel development for X-Energy. As described in X-Energy introduced its company and first product to Virginia chapter of ANS, X-Energy is a start-up company based in Maryland that is developing a modular high temperature gas cooled reactor. Each module will produce 50 […]

Filed Under: Gas Cooled Reactors, Pebble Bed Reactors, Podcast

X-Energy introduced its company and first product to Virginia chapter of ANS

October 30, 2015 By Rod Adams 48 Comments

On Tuesday, October 27, three leaders from X-Energy spoke to the Virginia ANS chapter about their company and the Xe-100, the high temperature, pebble bed gas reactor power system that they are designing. During the presentation, meeting attendees learned that X-Energy is an early phase start-up with a total staff of a few dozen people, […]

Filed Under: Advanced Atomic Technologies, Atomic Entrepreneurs, Gas Cooled Reactors, Graphite Moderated Reactors, New Nuclear, Pebble Bed Reactors, Small Nuclear Power Plants, Smaller reactors

Using portable nuclear generators to break petroleum logistical dependence circa 1963

October 27, 2015 By Rod Adams

Note: The initial version of this post was written based on an incorrect interpretation of the Roman numeral date stamp at the end of the video. The film was made in 1963, not 1968. The post was revised after a commenter provided the correct production date. End note. I have a theory about why the […]

Filed Under: Adams Engines, Advanced Atomic Technologies, Atomic Entrepreneurs, Gas Cooled Reactors, Pebble Bed Reactors, Small Nuclear Power Plants, Smaller reactors

HTR-PM – Nuclear-heated gas producing superheated steam

June 27, 2014 By Rod Adams

The first HTR-PM (High Temperature Reactor – Pebble Module), one of the more intriguing nuclear plant designs, is currently under construction on the coast of the Shidao Bay near Weihai, China. This system uses evolutionary engineering design principles that give it a high probability of success, assuming that the developers and financial supporters maintain their […]

Filed Under: Advanced Atomic Technologies, Gas Cooled Reactors, Graphite Moderated Reactors, International nuclear, New Nuclear, Pebble Bed Reactors, Small Nuclear Power Plants, Smaller reactors

Fission is an elegant way to heat a gas

June 26, 2014 By Rod Adams

What if it was possible to combine the low capital cost, reliability, and responsive operations of simple cycle combustion gas turbines with the low fuel cost and zero-emission capability of an actinide (uranium, thorium, or plutonium) fuel source? Machines like that could disrupt a few business models while giving the world’s economy a powerful new […]

Filed Under: Adams Engines, Advanced Atomic Technologies, Gas Cooled Reactors, Graphite Moderated Reactors, Pebble Bed Reactors, Small Nuclear Power Plants, Smaller reactors

Advances in high temperature nuclear reactor fuel – TRISO integrity at 1800 C!

September 26, 2013 By Rod Adams

The Idaho National Laboratory released the following exciting news on September 25, 2013. IDAHO FALLS — A safer and more efficient nuclear fuel is on the horizon. A team of researchers at the U.S. Department of Energy’s Idaho National Laboratory (INL) and Oak Ridge National Laboratory (ORNL) have reached a new milestone with tristructural-isotropic (TRISO) […]

Filed Under: Advanced Atomic Technologies, Fuel Comparisons, Gas Cooled Reactors, Graphite Moderated Reactors, Pebble Bed Reactors

Pebble bed reactor safety demonstration test – ABC video from 2007

November 20, 2011 By Rod Adams

I spent about 15 years trying (unsuccessfully) to get a small modular reactor company off the ground. Our concept was based on an adaptation of the successful German pebble bed demonstration reactor called the AVR. In 2003, Tsinghua University in China completed the construction of the HTR-10, which was essentially a direct copy of the […]

Filed Under: Gas Cooled Reactors, Graphite Moderated Reactors, New Nuclear, Pebble Bed Reactors, Small Nuclear Power Plants, Smaller reactors

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