NRC agrees NuScale SMR needs no back-up power

The US nuclear regulator is satisfied that NuScale Power's small modular reactor (SMR) design can operate safely without the need for safety-related electrical systems. The reactor uses passive safety features, such as relying on convection, not pumps, to circulate water in the primary circuit.

The US nuclear regulator is satisfied that NuScale Power's small modular reactor (SMR) design can operate safely without the need for safety-related electrical systems. The reactor uses passive safety features, such as relying on convection, not pumps, to circulate water in the primary circuit.

NuScale announced yesterday that the Nuclear Regulatory Commission (NRC) had concluded that "application of NuScale Power's novel safety design approach eliminates the need for Class 1E power".

A cutaway of the NuScale SMR (Image: NuScale)

Class 1E is the regulatory standard set for the design of safety-related nuclear power plant electrical systems. Such electrical equipment and systems are classed as essential to emergency reactor shutdown, containment isolation, reactor core cooling, and containment and reactor heat removal, or otherwise are essential in preventing a significant release of radioactive material to the environment. Currently, all nuclear power plants in the USA are required to have class 1E power supplies to ensure safety.

In its newly-released Safety Evaluation Report, the NRC concluded NuScale provided a method to justify that its SMR plant electric power supplies need not be classified as Class 1E.

NuScale's self-contained SMR design houses the reactor core, pressuriser and steam generator inside a single containment vessel. A single module can generate 50 MWe (gross) of electricity and is just under 25 meters in length, 4.6 meters in diameter and weighs around 450 tonnes. A power plant could include as many as 12 NuScale modules to produce as much as 600 MWe (gross). Each NuScale Power Module incorporates simple, redundant, diverse, and independent safety features.

In December 2016, NuScale submitted the first-ever SMR Design Certification Application (DCA) to the NRC, which the latter accepted on 15 March 2017. The application consisted of nearly 12,000 pages of technical information.

Dale Atkinson, NuScale's chief operating officer and chief nuclear officer, said: "We appreciate the NRC staff's focused and thorough analysis of the safety and reliability our SMR design offers and for issuing their findings so early in our DCA review."

He added, "Our approach to safety is a first in the nuclear industry and exemplifies the inherent safety of NuScale's SMR. This validation brings us another step closer to achieving our mission of delivering scalable advanced nuclear technology to produce the electricity, process heat and clean water needed to improve the quality of life for people around the world."

Last July, the NRC concluded that the highly integrated protection system platform developed for NuScale's SMR is acceptable for use in plant safety-related instrumentation and control systems. The hybrid analog and digital logic-based system comprises the safety function, communications, equipment interface and hardwired modules. All the modules operate independently and asynchronously.

The NRC's final report approving the reactor design is expected to be completed by September 2020. Once issued, a design certification is valid for 15 years in support of a combined licence application to construct and operate a power plant.

The first commercial NuScale power plant is planned for construction on the site of the Idaho National Laboratory for Utah Associated Municipal Power Systems and operated by Energy Northwest.

Researched and written
by World Nuclear News