Nuclear - Reverse Engineering
Reverse engineering saves thousands of testing hours
Equipment obsolescence is a huge challenge for nuclear plants that have been operating for decades, and electronic equipment is particularly challenging given advancements in technology over time. When it comes to replacing a nuclear plant component that is no longer commercially available, reverse engineering is a solution to keeping the component as similar as possible to the original. With advances in technology and materials, AZZ Nuclear | NLI frequently needs to re-engineer the design itself to create a functional equivalent using currently available components. This was the case with the Bailey 862 logic module, which was needed by a customer when original modules were no longer available.
The term “obsolescence” has several meanings. For example, 3-1/2” floppy disks are clearly obsolete technology, but can still be purchased by enterprising shoppers. The Bailey 862 is obsolete both in terms of technology and availability. It is one thing for the entire 862 to be obsolete, but certain components are simply no longer available, thereby eliminating the possibility of manufacturing an exact duplicate of the original 862.
There are certain sources for “hard to find” electronic components and in the case of the recent customer, it might have been possible to find all of the original components in an unused condition. But the plant needed more than 750 modules and it was unlikely that many components could be located while avoiding counterfeit, fraudulent, or substandard parts.
But even if only a few parts were obsolete, it does not make sense to manufacture a new design that uses 10 percent new technology and keeps the other 90 percent using obsolete technology. As long as the plant is forced to perform an equivalency evaluation anyway, it makes more sense to design a module that uses all new and available components, so that replacement parts can be easily obtained, or whole new modules manufactured.
The redesign of the Bailey 862 for the customer enabled several enhancements to be made. For one, smaller components allowed for the use of a single board compared with three boards on the original design. The stacking of three boards on top of one another had made troubleshooting and maintenance a nightmare for the plant. In addition, the original 862 used jumpers that were repositioned to program the module in the field. These were replaced with switches in the new design.
Testing the boards at AZZ Nuclear | NLI required four hours both before and after the burn in, which was the equivalent of three man-years of testing for the 750 boards. The customer also performed four hours of testing before installing each board. To facilitate testing, AZZ Nuclear | NLI’s Instrumentation Services also designed and built two automated test sets, reducing the test time per board from four hours to five minutes! The automated test sets reduced roughly 9,000 hours of testing down to about 190 hours. When the job was completed, the customer had replacement control modules that surpassed the obsolete parts in both performance and maintainability and saved thousands of hours of testing.