In addition to the Rolls-Royce small modular reactor (SMR) SMR timed to coincide with the COP26 environmental conference, another type of SMR has been in the news. The natrium reactor, financed by Bill Gates’ Terrapower, announced the achievement of certain development milestones. Wyoming’s governor announced that Terrapower would build its demonstration reactor at a former coal plant site, the specific site to be announced later this year. Mr. Gates referred to a $4 billion price tag for this 345 MW facility although other sources quoted an estimated ultimate commercial cost as low as $1 billion.
Natrium, as many of our readers know, is simply the Latin word for sodium. The natrium reactor uses sodium as a moderator instead of water or heavy water as in most conventional, commercial reactors today. Sodium has several advantages over water as a reactor moderator because: 1) it can absorb more heat than water, 2) it has a higher thermodynamic efficiency vs water cooled reactors, 3) it does not need to be pressurized, 4) and it does not corrode steel piping and other components.
In its proposed configuration this sodium cooled reactor is designed with a “molten salt based energy storage” system which will permit the nominally 345 MW reactor to produce up to 550 MWs for up to five hours. The developers refer to this feature as “integrated energy storage and flexible power generation.” Also they claim this reactor is intended to be “seamlessly integrated with renewable resources.” Due to the molten salt storage feature, this is reactor can also behave like a large battery—but without the additional expense for that daily flexibility.
The disadvantages of sodium as a reactor moderator are also well known—it ignites on contact with air and moisture. This is not a mere hypothetical. Japan’s Monju sodium-cooled reactor experienced an explosion and fire of precisely this type in December 1995. “Fortunately” the leak occurred on the secondary (non-radioactive) side of the plant but the resulting fire was allegedly hot enough to melt the steel walls in the rooms in which it was ultimately contained. The other disadvantage of the sodium reactor concerns regarding nuclear proliferation. This is a “breeder” type of reactor, producing fissionable materials which could fall into the wrong hands. We should add that the only countries presently operating plants of this type are those with active nuclear weapons development programs—Russia, China, and India. (US weapons development at Savannah River and TVA facilities do not involve breeder type plants.)
There is a considerable amount of financial firepower behind the natrium project including Mr Gates’ Terrapower and GE Hitachi Nuclear that are developing the design. Warren Buffett’s PacifiCorp will provide the initial reactor site. Bechtel is the principal construction partner.
We do get the appeal of sodium SMRs. Sodium offers enormous thermodynamic efficiencies versus water in a reactor. There were literally dozens of these units operating about 40 years ago. Today only a handful remain. But the sodium reactor, being a finicky technology that could abet nuclear proliferation we think that it might only have niche commercial appeal despite the marquee names associated with it.
However, there is one truly small modular reactor design that may truly live up to its name. The NuScale reactor design, which has Fluor Corp. as its principal shareholder, is much smaller than the 300-400+ MW reactors offered by Rolls-Royce or Natrium. The NuScale reactor “modules” are up to a 77 MW reactor with the reactor core, steam generator, and pressurizer all contained in a single vessel. These modules are submerged in a below grade, water filled pool. They feature natural circulation for emergency feedwater cooling and therefore require no external emergency power for safe shutdown. This is a profoundly important safety feature.
Fluor plans to construct an initial 720 MW facility, 12 SMRs, at the government’s Idaho National Laboratory. The power customer is UAMPS (Utah Associated Municipal Power Systems). The company has already received both a Final Safety Evaluation Report and a Standard Design Approval from the US Nuclear Regulatory Commission. NuScale is promising a 36 month build time “from the first safety concrete.” NuScale estimates capitalized construction costs of $2,850 per kw versus their estimate of $5,587/kw for large reactors.
NuScale plans to have their first module operational by 2029 with the remaining Idaho units on line the following year. In addition to power generation, these reactors can be used for district heating, desalination, and other process heat applications. The company's website stated they would be “ready to provide modules to clients by 2027.” Like their competitors in the UK they are aggressively targeting international clients hoping to develop a substantial export business.
It’s difficult to gauge the appetite for new nuclear power generating facilities. Huge cost overruns have made a mockery of nuclear technology’s initial promise—too cheap to meter. Instead, it’s become too expensive to matter. But NuScale is offering nuclear power at a relatively affordable price, rapid construction, and passive safety features. This is not a “Power Point Reactor” as some have disparagingly referred to designs that are years if not decades away. If there is a demand for new base load nuclear NuScale certainly appears to lead the pack. But we might have to wait eight years to find out.
By Leonard Hyman and Bill Tilles for Oilprice.com
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