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Tiny but Mighty, This Reactor's Controls Are Entirely Digital

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The U.S. Nuclear Regulatory Commission has licensed Purdue University Reactor Number One (PUR-1), which the university said is the first entirely digital nuclear reactor instrumentation and control system in the country.

The reactor and facility, originally built in 1962, could aid the widespread implementation of digital technology in both research and industry reactors.

Clive Townsend, supervisor for Purdue's reactor, said, “We’re going from the vacuum tubes and hand-soldered wires of the ’60s, to LEDs, ethernet cables and advanced electronics.”

Traditional analog consoles make it difficult to take research data accurately and quickly, the university said. A digital system allows values to be measured instantly and means that more data can be processed and analyzed. Capabilities that may be possible include predictive analytics, machine learning and artificial intelligence.

Purdue's reactor is licensed to produce up to 1 kilowatt of thermal power, roughly the energy demand of a hair dryer or a toaster. The reactor's core is 2 ft3 in volume and sits at the bottom of a 17 ft deep cooling pool of water that measures 8 ft in diameter. This allows the core to be viewed while it is operating.

Fuel conversion

The PUR-1 originally used highly enriched, or "weapons-grade," uranium as fuel. In 1982, the government began to convert civilian reactors to low-enriched uranium. Conversion of the Purdue reactor was completed in 2007.

Over the years, the NRC has been deliberate in considering and approving digital control equipment in the nation's fleet of nuclear generating stations. Many control rooms at commercial reactors continue to feature banks of analog controls, displays and switches.

Purdue developed and built the digital system along with Mirion Technologies and the Curtiss-Wright Corp. 

The digital conversion of PUR-1 began in 2012, when the U.S. Department of Energy awarded Purdue a grant through its Nuclear Energy University Program to replace reactor equipment with an upgraded instrumentation and control system. 

German components

Some of the parts included in the NRC approval are certified under the German Nuclear Safety Standards Commission (KTA), rather than domestic U.S. standards. Historically, the NRC has accepted only parts certified under domestic standards, which Purdue said are generally cost-prohibitive for use. The NRC accepted the German-certified parts through the agency’s initiative for a "risk-informed and performance-based" regulatory process.

 “The fact that the NRC is accepting a digital console for a small research reactor, with parts certified under the KTA standards, signals the regulatory body moving toward approval in a large industry reactor,” Townsend said.

The university said that its digital reactor may offer several benefits both to industry players and educational settings. As a cyberphysical test bed, collaborators and corporate partners will be able to evaluate simulations of industry reactors using Purdue’s facility as a model and apply lessons learned and best practice improvements to their own reactors.

“Testing code and simulations in smaller university facilities allows more flexibility, ease of access and quicker development cycles than would be available at larger industrial partners,” said Robert Bean, the PUR-1 facility director and an assistant professor of nuclear engineering at Purdue. “At low cost, researchers will be able to quickly evaluate their work and achieve full-scale deployment.”

Digital technology also means that Purdue can use the reactor to send live data to remote locations, helping researchers match reactor status in real time to experimental results, and students to visualize from their monitors how a reactor responds.

DW Keefer's picture

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Discussions

Bob Meinetz's picture
Bob Meinetz on Jul 26, 2019 3:20 pm GMT

DW, when I visited NuScale Power last October, among the first questions for the engineer demonstrating the simulated, all-digital control room of their 12-unit Small Modular Reactor (SMR) array had to do with security: preventing cyberthreats, safe software upgrades, preventing sabotage.

Suffice to say (and typical for U.S. nuclear engineering efforts) security and safety were their top two priorities, and the fundamentals hadn't changed. Both the strict "air wall" blocking external access, and hardened internal access, are reminiscent of those protecting Arpanet and NORAD systems in the 1970s-80s. Unsurprisingly, details were unavailable.

As their name suggests, NuScale's marketing approach involves scaling down multi-gigawatt reactor designs - lowering operating temperature and pressure, splitting generation among several modular units. Economics is one reason. Simplified, standardized construction is another.

I have to think public perception plays a part in NuScale's design, too. It's almost as if engineers are thinking: "If the public is afraid of big powerful things, let's make a bunch of smaller, less-powerful things and hook them together." Maybe it was inevitable. But that nuclear engineers, in 2019, are forced to sacrifice economies of scale at the altar of misperceptions and downright ignorance reflects a lack of public confidence in U.S. government going all the way to the top. I suppose I shouldn't be surprised by that, either.

Engineer Heather Matteson at the controls of Diablo Canyon Nuclear Power Plant, Unit 1. Can you find the USB port engineers use to connect to the internet? (No you can't, because there isn't one. That's by design.)

Matt Chester's picture
Matt Chester on Jul 26, 2019 4:30 pm GMT

lack of public confidence in U.S. government going all the way to the top

...I mean, yeah that's sort of where we are, as you point out! Unfortunate for the people who have earned the trust, but an understandable position to come from

Matt Chester's picture
Matt Chester on Jul 26, 2019 4:31 pm GMT

“Testing code and simulations in smaller university facilities allows more flexibility, ease of access and quicker development cycles than would be available at larger industrial partners,” said Robert Bean, the PUR-1 facility director and an assistant professor of nuclear engineering at Purdue. “At low cost, researchers will be able to quickly evaluate their work and achieve full-scale deployment.”

Digital technology also means that Purdue can use the reactor to send live data to remote locations, helping researchers match reactor status in real time to experimental results, and students to visualize from their monitors how a reactor responds.

This is a neat application of the technology-- almost reminds me of similar digitization of some medical practices that help in research, carrying out care, and educating the next generation of professionals

David Svarrer's picture
David Svarrer on Jul 31, 2019 3:56 pm GMT

Well. 

I would like to ask ONE question: 

Given an Electro-Magnetic Pulse - which statistically will hit us, one day - and which last time - caused serious damage to electrical circuits (back then when we had telegraph wires etc.) - what happens?

What is the default mechanism, in this reactor system, if we assume that a random subset of all electronic circuits completely stops working, another random subset of circuits starts malfunctioning, yet another random subset of computer driven controls starts malfunctioning - which can include watch dog hardware - and another random subset works as it should?

I have worked with mechatronics for 37 years, mainly within IT software/hardware, and with sensors/actuators, robotics etc. - and with the width of the solar flares in mind, and the position of Earth in the orbit around the sun, there is a non-negligible risk of a powerful magnetic storm on Earth, which will or will not cause issues :-)

So - with the above scenario - what is the response by the reactor systems pure mechanical controls (those which are not at all controlled in any way by any electric circuit) in case of all prospect combinatoric scenarios of circuit malfunction?

If this is not solved, then this reactor is just like the major parts of the other ones - it is a ticking bomb :-)

 

Bob Meinetz's picture
Bob Meinetz on Aug 2, 2019 8:00 pm GMT

David, if you're familiar with mechatronics you're probably aware of EM shielding. Shielding sensitive electronics from EM pulses is not rocket science, but it is expensive. And all the control hardware at nuclear plants is shielded in nested Faraday cages, to pretty much eliminate the possibility of an EM pulse wreaking havoc.

In truth, digital control systems are far more vulnerable to disruption by an EM pulse than analog ones. Though analog systems are too heavy for use on commercial jets, they're fine for nuclear plants, which are designed to stay put for a long, long time. New reactors, like the Westinghouse AP 1000, are passively safe - they shut down without help from any external power at all.

But you're correct - we don't know for certain reactors couldn't be induced to melt down by ultra-powerful, imaginary EM pulses. Nuclear engineers don't care about protecting reactors from imaginary pulses, however - they care about protecting them from real ones.

Gary Hilberg's picture
Gary Hilberg on Aug 12, 2019 4:46 pm GMT

David - The standard plant design if for the control rods to be held out of the core by electrical magnetic means and on loss of power, the reactor is shut down.  Bob brings up the natural circulation cooling capability of the AP1000 design - i.e. it will cool itself without power.  Interestingly the founders of NuScale did the AP1000 cooling design and then applied their learnings to their SMR design for NuScale.  Natural circulation cooling for pressurized water reactors is well proven, the Trident class SSBN (first commissioned in 1981) uses the S8G reactor which routinely runs without reactor coolant pumps during normal operations.   Also the nuclear operators are continuously evaluating their response to these senarios, the risks associated with an out of control fission on our reactor fleet is small.  I would suspect that there are many hazardous processes that are much more reliant on digital controls and electricity to maintain their processes safe.   

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