Metropolis Works, Metropolis,
Illinois (MTW) is reporting a failure to follow procedure related to the installation of valves in
UF6 cylinders.
A violation of ANSI Standard N14.1 (2001) 'Uranium Hexafluoride Packaging for Transport', Section 6.14.6 was reported 26 October, 2005. This is a reportable event because it is a violation of an applicable national standard and also an action outside the licensee's procedures. ANSI N14-1 (2001) 6.14.6 states, 'No material of any kind other than the specified solder shall be used on the threads to facilitate installation {of cylinder valves into the UH6 type 48Y cylinders}.' Contrary to that standard, MTW site maintenance personnel did use Teflon spray to facilitate installation of cylinder valves into type 48Y cylinders. Use of a thread lubricant, such as Teflon, can be expected to increase the degree the valve threads are engaged for a given torque. Teflon is a fluorinated compound and is not a chemical hazard in contact with UF6.
This issue was discovered when USEC inspectors noted white residue around cylinder valves previously replaced by the licensee when those valves were later replaced by the cylinder manufacturer. Analysis of the residue showed it was Teflon. USEC notified the licensee of the finding 25 October 2005. Interviews with maintenance workers disclosed that Teflon had been used when replacing some cylinder valves. The licensee is investigating the quantity and type of cylinders that might have been subjected to Teflon during valve replacement. Notification of all customers that might have received cylinders with valves installed with Teflon is in progress.
The licensee notified NRC Region 2 (D. Hartland).
Notified R2DO (Ernstes).