Reliability Analysis and 30 Years of Operational Performance of the GHARR-1 Control Rod System

This study evaluates the 30-year operational reliability of the Ghana Research Reactor-1 (GHARR-1) control rod drive mechanism (CRDM) from its criticality on December 17, 1994, to August 7, 2025. To address a 4.93-year left-truncation period (1994–1999) when records were undocumented, a conditional reliability framework was utilized to analyze 31 subsequent failure events. Failures were categorized by physical nature (mechanical versus electrical) and maintenance logic (repairable versus non-repairable). The results indicate that the system has transitioned from its stable useful-life phase into a definitive wear-out phase. The most frequent failure mode was the inability of the control rod to move upward (n = 12), exhibiting the highest failure rate (λ = 0.4668 yr−1) and a mean time between failures of 2.14 years. While electrical failures were more prevalent (n = 22), primarily involving instrumentation drift and circuit malfunctions, mechanical failures (n = 9) such as structural wire snaps and sudden rod drops emerged predominantly during the later operational stages (at 25–30 years). The clustering of safety-critical failures in the final five years demonstrates that after 30 years, the CRDM is nearing its design-life threshold. The study concludes that standard annual maintenance is insufficient for aging miniature neutron source reactor facilities and recommends a transition toward predictive, condition-based maintenance strategies. These empirical findings provide essential benchmarks for aging management and life extension protocols for similar research reactors globally.