On April 6, for our Zoom noon meeting, Douglas Hunter (CEO and General Manager of Utah Associated Municipal Power Systems – “UAMPS”) gave us a fast-paced and data-packed presentation on projects currently underway at his joint-action agency. Although he started with a review of the energy mix of his organization and their overarching goals for the future, he spent much of his time talking about their current efforts toward developing and deploying a small modular nuclear reactor system.
UAMPS, an organization of some 50 electric utilities across seven western states, operates in an environment where there is a broad range of current power sources (including coal, natural gas, and hydroelectric), and where bringing anything new on line requires long lead times, but where the Intergovernmental Panel on Climate Change (IPCC) tells us that we have only a few years to make changes in our energy systems to avoid environmental catastrophe. Any changes must be made within a framework of resource criteria: reliable (integrated portfolio, ease of dispatchability, and low outage rate), economical (levelized cost of energy), and clean (following both government regulations and social acceptability). The evolving energy mix must loose carbon-based resources (with the possible exception of natural gas over the short to medium term). This transition is being aided by significant increases in efficiency for consumer products and businesses. He figures that the transition to carbon-free electricity, including renewables, harvesting of waste heat, hydro pumped storage, and hydrogen combustion (either alone or combined with methane) will still require some nuclear power.
The remainder of the presentation focused on their Carbon Free Power Project, their ongoing effort to develop and get approval for small modular nuclear reactors. Types of nuclear reactors include cooling by light water (either boiling or pressurized), liquid sodium, or gas. All of the approximately 100 nuclear reactors currently operating in the US (and the two that are currently under construction) are cooled by boiling light water and all were constructed on-site with heavy-duty safety redundancies as required by the Nuclear Regulatory Commission (NRC).
In contrast, their Carbon Free Power Project is focused on a pressurized light water design (the NuScale Power design), a design that allows manufacture in a central factory of individual modules that can then be transported to a power-plant site. Their current plans call for installation of six modules at a site at Idaho National Laboratory, the combination capable of generating 462 megawatts (MW) total, up and running by November, 2030. Each module will be 80’ tall and 15’ in diameter and the whole project is designed to produce carbon-free power for less than $58 per MWhour (financing is designed such that, if they can’t reach that metric, they get their sunk costs back). Each module includes the reactor vessel, steam generators, pressurizer, and containment in one package. The nuclear core is near the bottom of the module. Reactor heat is absorbed by pressurized water in a closed circuit such that this primary hot water, lower in density, “floats” upward to the heat exchanger, where the heat is transferred to a secondary water system for generating the electricity. The now cooler primary water sinks, in a separate part of the system, back to the nuclear core to start the cycle over again. The rate of the nuclear reaction is controlled by rods that are pulled upward from the reactor core. In the event of a power or other catastrophic failure, the rods are automatically dropped back into the nuclear core, immediately stopping the reaction. The six modules will be housed below ground level in a concrete structure (designed to protect the modules from outside, not to contain any nuclear episode; the containment vessel is part of the module structure). The concrete structure will be filled with water at ambient temperature and pressure such that, in the event of a catastrophic failure and following the automatic insertion of the control rods, heating and evaporation of that water will cool the modules to low levels in 30 days. The simplicity and passive nature of this system and the lack of any need for external power enhances the safety of the system. This system has already been licensed by the NRC and allows an evacuation zone at the fence line of the site, not the 10 mile radius required for currently operating designs.
The design calls for cooling of the secondary water (after it generates electricity) by air or dry cooling, thereby saving large amounts of water. The modular design, small size of modules, and multiple modules at each site allow for efficient load-following strategies such that they can power up in 27 minutes and power down in 8 minutes. Used fuel (in the absence of any future approval for recycling fuel) will be stored on site, first in the water of the reactor building, then in steel containers with concrete shells for up to 100 years, both systems already approved for use. Used fuel is the property of the NRC, which pays rent for the storage space.
All of this is dependent on NRC licensing which is currently a lengthy process but may be speeded up as a result of the factory-based process for construction, vs. the current on-site process for conventional reactors.
Another attractive feature of this design is that the technology is ideal for deployment at retiring coal power plants. In that case, the land, water, and transmission facilities are already in place and, of the displaced workforce, only 15% are estimated to require any new formal educational certification/degrees.
Questions:
Will any modifications to the grid be required? “The Grid” is not really one thing; pieces of it are scattered all over the country with various levels of interconnectedness. The biggest weakness is a terrorist attack. The recent Federal infrastructure bill should allow for enhancing and improving the current system as well as building new parts. The grid is “studied” every three minutes to allow for rapid adjustments as needed; any departure from 60 herz (cycles per second), currently resulting mostly from load issues but, with transition to a larger variety of resources, ultimately from variation in both load and resource availability.
Further clarification of waste issues? For light-water reactors, some 93 – 95% of the uranium is still left at “depletion” so replacement is required every two years. Liquid sodium reactors, potentially more efficient, require more concentrated fuel, currently only available from Russia. Although there is much debate about nuclear waste, currently all of the waste is stored at the reactor sites. The fuel is pellets so any lost pieces may be quickly recovered. Historically, coal is much more deadly than is uranium.
Any government support or subsidy? The DOE has provided some $1.4B, some 23% of the cost of the project, front-loaded to encourage development of the design. Similar grants have been provided to other design groups. Although support or focus tends to vary from administration to administration, the DOE is able to move money around to match changes. That said, although the administration moves the money around, congress actually has to appropriate the money.
How does the cost per MWh compare with coal or gas? Compared with other non-carbon sources of power, the price is similar. The $58 per MW metric against which this project is working is comparable to a combined-cycle plant. The carbon cost for nuclear is zero whereas coal produces about one ton of carbon per MWh, gas about ½ ton per MWh. Coal cost, going forward, is just maintenance since the coal plants are nominally paid off. Nuclear plants can supplement renewable sources of electricity.
Will there be any problems associated with the transition to electric vehicles? Although this is independent of nuclear vs. other power sources, the current installed system has transformers designed to produce 100 amp service whereas transition to all electric vehicles will require retrofitting or replacing transformers to 200 – 500 amps. As a parallel issue, Mr. Hunter pointed out that commercial vehicles may be more likely to use hydrogen with fuel cells to power electric motors to the wheels – still electric vehicles, but with a different source for energy.