Highly Accurate Nuclear Fuel Assembly Mapping System by Newton Labs to Eclipse Legacy Video Micrometer Measuring Process at Exelon Facilities

Several significant capabilities of the NM200E system, which is composed of a radiation-resistant camera head and control console, set it apart from legacy nozzle gap measurement. The accuracy of the NM200E is derived from sophisticated, Newton-developed software algorithms that compensate for the visually distorting thermal turbulence and use the core baffles as positional references. The software enables the precise global mapping of fuel assembly S-hole positions, including any degree of misalignment or nozzle rotation. The legacy video method merely gauges the relative nozzle gap variations, limiting an operator to only being able to infer the position of S-holes.

On the NM200E operator’s console the actual S-hole positions of individual nozzles are graphically superimposed upon the “ideal or design” locations. Out-of-tolerance S-holes are immediately apparent and their precise locations are digitally recorded for future reference. An overall core map is also displayed on the console which shows each of the mapped nozzles in one of three colors: green for within tolerance, yellow for within tolerance-but greater than the specified gap, and red for out-of-tolerance. In contrast, legacy video micrometer accuracy is highly dependent on operator experience and camera orientation, processes that are handled automatically and consistently by the NM200E.

The duration of the mapping process is important to Exelon managers and the NM200E features a considerably shorter mapping time compared to the legacy video process. The total mapping time for the NM200E system is two hours or less. A major factor for the speed of the NM200E system, beyond software processing time, is an expanded field of view. The NM200E registers a field view of five by four nozzles, compared to a video micrometer’s field of view that is no more than one and a half fuel nozzles wide.

“This system significantly improves the method for determining fuel assembly top nozzle positioning relative to previous processes,” said David B. Kelly, Exelon Nuclear PWR Reactor Service Manager. “It allows the operator multiple visual indications of the fuel assembly top nozzle locations. By mounting the camera head to the Refuel Machine rigid mast, we were able to improve production time and increase the accuracy of the system,” Kelly said.

“We are very pleased that this mapping product is adopted by Exelon, the team that gave us so much support and access during its development,” stated John W. Bramblet, President and CEO of Newton Labs. “In return, the accuracy and speed of the NM200E will significantly contribute toward the quality of fuel assembly placement confidence and shorter outage periods.”

The NM200E Fuel Assembly Mapping System, developed in conjunction with Exelon, is marketed worldwide by Newton Labs along with its companion product, the NM200UW Nuclear Underwater Laser Scanner.