SMR safety feature validated

A rendering of a power module for NuScale Power’s small module reactor design. Each reactor could contain up to 12 modules. Courtesy of NuScale Power

A key regulatory agency determined NuScale’s small modular reactor design eliminates the need for an electrical safety system required of every other nuclear reactor in the United States. 

Unique to commercial reactors, NuScale’s novel design features passive safety features that automatically engage in case of emergency.

The U.S. Nuclear Regulatory Commission’s determination that the SMR design doesn’t require safety related electrical systems — class 1E power — is a key step forward, NuScale spokeswoman Mariam Nabizad said.

“This is really good, exciting news for us because it validates what we put forward as part of the foundation of our safety design. It moves us closer to certification,” she said.

The NRC began in March the mandatory 40-month review of NuScale’s design, which includes up to 12 small reactors, or “power modules,” at one facility.

NuScale’s first reactor is expected to be built by 2026 at the U.S. Department of Energy desert site west of Idaho Falls. It will be operated by Utah Associated Municipal Power Systems, a consortium of western utilities that includes Idaho Falls Power.

For most reactors, the safe position for a component — such as a valve — depends on the emergency event. Subsequently, electricity is required to move the component. It’s also needed to power instrumentation alerting an operator when to take action, which makes power loss problematic.

During the 2011 Fukushima Daiichi nuclear plant disaster in Japan, the electrical grid was knocked out by an earthquake and on-site diesel generators were swamped by tsunami waters, which prevented proper reactor cool down.

NuScale SMR components have one safe position that is automatically engaged when power is lost. No operator actions are necessary.

“Loss of all power events typically are some of the most challenging events for nuclear power plants. Eliminating the need for electric power avoids this entire class of events. As a result, overall safety is significantly improved,” NuScale Chief Commercial Officer Thomas Mundy said in a statement.

Additionally, SMRs are submerged in a water pool referred to as an “ultimate heat sink.” The reactor’s small size means no additional cooling water must be pumped with electricity, Mundy said.

Class 1E safety equipment, mandated to prevent nuclear disasters, is expensive to purchase and maintain. NuScale’s SMR design doesn’t require class 1E equipment, which makes the reactor more competitive in the energy market.

“By eliminating class 1E power supply equipment, the cost to build, operate and maintain the NuScale design is significantly reduced,” Mundy said.

Reporter Kevin Trevellyan can be reached at 208-542-6762.