Thermo Fisher Scientific Radiation Monitor: Electronic Channel Design Correction by NES

NES recently completed a successful project to correct a significant design issue in newly reverse-engineered radiation monitors. The reverse engineering and initial construction of the monitors were performed by another vendor, but NES was called in when the units failed to function properly after installation.

During the customer's refueling outage, they discovered that the monitors would stop working after a testing circuit was activated. This issue required immediate attention to ensure the plant could complete the outage and resume operations. NES’s skilled engineers and technicians swiftly mobilized to investigate the problem. After a thorough evaluation of the circuit, the issue was traced to an undersized switching transistor in one of the modules. It was found that whenever a switch on the front panel was pressed, the transistor would draw excessive current, causing it to fail. 

Upon further analysis, NES determined that the reverse-engineered design had significantly undersized the transistor. NES quickly sourced a suitable replacement and performed extensive testing with the new component. During testing, a secondary issue was uncovered: a solenoid remained energized after the switch was released, contrary to the original design's intent, leading to the failure of the replacement transistor. This problem was traced to a misconfigured capacitor in the reverse-engineered design.

To fully resolve these issues, NES designed, built, and tested a custom daughterboard that included the necessary circuitry to correct both design flaws in the module. Additionally, at the customer's request, NES incorporated a calibration potentiometer that had been omitted in the reverse-engineered version.

Despite the intense time constraints of the refueling outage, NES committed the necessary resources and worked through weekends to deliver a solution that met the customer's aggressive schedule.

NES’s commitment to quality and rapid response ensured that the plant could get back online without delay.