Duke Energy offers the following response:
1) At the nuclear site we have moved away from Thoriated tungsten electrodes (EWTh-2 is the AWS classification) (I would stay away from calling it Weld Rod as that may get misconstrued). However, for critical welds that receive volumetric inspection we may allow the welder to use EWTh-2, since most welders prefer them over the alternative we originally selected. Our original selection was 2% Ceriated tungsten (EWCe-2) and they were not liked by the welders. We have proven this in a blind weld test were two welders selected the Ceriated tungsten as the worst when comparing 2% Ceriated, 1.5% Lanthanated, and 2% Thoriated on similar base materials and welding parameters. After the blind test we had good feedback with the 2% Lanthanated (EWLa-2). Therefore, we are moving towards EWLa-2 and away from EWCe-2. For an alternative to Thoriated electrodes I would recommend the EWLa-2. With all that said. If the tungsten grinders provided have adequate filtration for the dust, Thoriated tungsten should not be an issue. We chose to err on the side of conservatism and have been phased out EWTh-2 electrodes and using them for only special applications. If welders have confidence with EWLa-2 we may eventually never allow the use of EWTh-2. We are not at that point yet. 2) My contact information is below. Nicholas I. Mohr Engineer III NGD Welding Engineer Nuclear Technical Services Materials and NDE Services Phone: 704-382-2973 Fax: 704-382-3797 Cell: 614-325-0532 [email protected]<mailto:[email protected]> Graham Johnson, CHP General Office Radiation Protection From: [email protected] [mailto:[email protected]] On Behalf Of [email protected] Sent: Tuesday, November 16, 2010 11:50 AM To: [email protected] Subject: Powernet: WELD ROD TH232 CONTRIBUTES TO DETECTABLE ALPHA- DOES YOUR SITE USE LANTHANUM RODS? LaSalle is requesting the following information: 1. Does your site use lanthanum rods for welding? 1. Any other information such as site contact, application, etc., if available. Background; We had some Th-232 alpha issues in our spring outage related to grinding weld rod/tips. Out of that came the following action; RP to benchmark industry to see if other stations use lanthanum weld rod (lanthanum rods do not contain natural alpha emitter isotopes but provide as good a weld). From benchmark, determine if such rods should be considered for use at LaSalle. These type of rods are much more expensive than the regular weld rods. Thanks, EdWolfe ExelonNuclear LaSalleStation SeniorALARA Analyst *Telephone:815.415.2521 *Email:[email protected] *Fax: 815.415.4018 On-sitepager: 815.415.2521 Off-sitepager: 815.983.0811 ************************************************** This e-mail and any of its attachments may contain Exelon Corporation proprietary information, which is privileged, confidential, or subject to copyright belonging to the Exelon Corporation family of Companies. This e-mail is intended solely for the use of the individual or entity to which it is addressed. If you are not the intended recipient of this e-mail, you are hereby notified that any dissemination, distribution, copying, or action taken in relation to the contents of and attachments to this e-mail is strictly prohibited and may be unlawful. If you have received this e-mail in error, please notify the sender immediately and permanently delete the original and any copy of this e-mail and any printout. Thank You. **************************************************
