Current Event Notification Report for December 16, 2009
"During a review of a High-Energy Line Break (HELB) calculation, valve FBV0146 on a 3" Auxiliary Steam line, FB-093-HBD-3", was found to be kept normally open. This is not consistent with HELB analysis, which assumes flow in line FB-093-HBD-3" is restricted by an orifice plate or isolated by FBV0146. This HELB analysis classified FB-093-HBD-3" as a moderate-energy line downstream of FBV0146 as a result of line isolation.
"No orifice plate was installed, and line FB-093-HBD-3" downstream of the FBV0146 is considered a high-energy line if FBV0146 is open. A room containing line FB-093-HBD-3" downstream from FBV0146 includes several components, the most critical of which are two RCS [Reactor Coolant System] pressure transmitters in one train which are used to provide indications during post-accident conditions. This configuration is therefore outside of current HELB analysis and potentially represents a condition that significantly degrades plant safety.
