CONDITION MONITORING | DIGITAL METERING
One size fits all metering
Why has the Nuclear Power Industry failed to embrace and benefit from the digital revolution? Despite the obvious benefits it offers like higher reliability, accuracy, efficiency, and return on investment, nuclear operators have resisted adopting digital metering. Could that be about to change?
FOR OVER 60 YEARS THE entire world has embraced the digital technology revolution and has been steadily reaping the financial, efficiency and reliability benefits. Everyone except the nuclear power industry, that is. One example of this reluctance to adopt digital
OTEK Corporation Dr Otto P. Fest
technology comes from the continued use of analog metering. The inaccuracy, unreliability and limited life expectancy of this obsolete approach forces the industry to operate at below-optimum profitability. It’s a decision costing millions of dollars to all involved, from consumers to investors. The high cost and quantity of spare Class 1E meters held in emergency inventory was, and is, unaffordable, especially for a company owning 20 or more I&C rooms and simulators. Every Class 1E analog meter in the control room must have a spare Class 1E meter in inventory for emergency use. The problem is augmented by the inevitable high cost of replacement analog meters due to both their increasing obsolescence and low demand caused by the technical evolution to digital technologies. In other words, as the famous scientist Charles Darwin said, “Evolve or Perish”. What are the options for the industry to eliminate the millions of dollars wasted in spares while also increasing reliability, efficiency and ROI but without making any gross changes to existing installations?
Solving the spares inventory challenge One solution is to copy D’Arsonval’s “one movement” Analog meter design of 1856, but as a completely digital version. This approach nonetheless avoids going through expensive NRC cyber -security compliance to NEI08-09 by developing a “one movement-one signal and power” universal display and adapter plates to convert existing panel cut-outs to accept any display. The universal display also requires a new universal input/output signal, control and power circuit to convert all inputs & outputs to the “one movement” requirement of all displays. This solution delivers the most important outcome by eliminating the need for multiple same “movement” spare meters with different scale plates, colors, text, and calibration by developing a new printing technique. Instead of the conventional approach, a self-adhesive scale plate sticks to the front of the filter and can be field replaceable. It allows the same meter to be used for any and all process signals, power or outputs and can be printed to suit. Because of its simplicity and the fact that no changes to
the existing panel, wiring, signal, power or operators are required, the universal scale device is fully “plug and play” and as a result was christened the PNP. Plug and Play (PNP) is a stand-alone direct replacement
for obsolete analog and digital meters requiring no changes to existing installation, panel cut-out, signals, wiring or operator training while improving efficiency due to higher accuracy and resolution and a better human/machine interface. At the same time, it eliminates the multimillion dollar “spares” inventory to a mere ~$25,000-worth of “one for all” spares and replaceable “sticky” scale plates.
Above: Control rooms present particular challenges for spares inventory Photo credit: Ratthawut Konkham/
Shutterstock.com
30 | August 2022 |
www.neimagazine.com
Counting the cost of analog spares For NPP A: there are a total of around 640 obsolete analog meters. Of these about 445 are VMI9222 and around 180 are VMI9223. Assuming that of the 625 VMI meters there are around 400 Class 1E and some 225 CG, with about 20 different input signals and around 250 different scale plates, three different power inputs, two different control outputs, and in the spares inventory one each of every “unique” Class 1E meter. The total spares catalogue runs to approximately 300 meters at a present cost of some $10,000 each or around $3m of spares inventory. About 20 obsolete analog meters are replaced at the plant every year, so it’s possible that all the 640 analogs will be replaced within the NPP’s current licence period. Will the present supplier have enough old meters to rebuild to
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