Resolution of Generic Safety Issues: NMSS-0019. Control Unit Failures of Classic Nucletron HDR Units ( NUREG-0933, Main Report with Supplements 1–34 )
Several control unit failures in Nucletron Classic Model HDR units occurred over the span of three years: two were reported in 1997; four in 1998; and three in 1999. These nine control unit failures indicated an ongoing problem with unexplained control unit failures. Nucletron continued to investigate the ongoing control unit failures and believes it found the root cause of the failures and subsequently developed appropriate corrective measures. Affected licensees were to be informed and any necessary additional actions were to be taken to ensure that safety was maintained.
This issue1780 was resolved with the issuance of Information Notice 99-23.1783 Additional follow-up with Nucletron on their corrective measures was deemed unnecessary following an analysis of the failures that deemed them to be of low safety significance.