NMSS-0010: Troxler Gauge Source Rod Weld Failures

DESCRIPTION

This issue was identified[1] by NMSS after it was reported in June 1997 that the source from a Troxler moisture density gauge broke off the source rod and was left at a temporary job site. Prior to this event, there had been

6 known disconnects and 57 additional devices with cracked welds since 1996, and NRC Information Notice

96-52[2] had been issued to alert portable gauge licensees and vendors to the potential for cracks to develop in the insertion rod of Troxler Model 3400 portable moisture density gauges. If not detected early, the cracks may propagate, eventually leading to complete failure of the insertion rod and release of the contained radioactive material.

CONCLUSION In July 1997, NMSS and representatives from the state of North Carolina met with Troxler to discuss the continuing problem of cracked and broken source rods. Between July 1997 and April 1998, the staff worked with the state of North Carolina on a Consent Order to Troxler which required Troxler to issue a customer bulletin, conduct accelerated device inspections, revise procedures, and perform additional tests. It is expected that the customer bulletin will address the problem and that Troxler will request their customers to have their

gauges inspected. The issue was given a medium priority ranking [3] and was later closed out after an NRC study showed that the gauge failure rate was low and Troxler had corrected its design.[4]