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| Start date | Reporting criterion | Title | Event description | System | LER | |
|---|---|---|---|---|---|---|
| ENS 49781 | 31 January 2014 05:00:00 | 10 CFR 50.55(e) 10 CFR 21.21(a)(2), Interim Report for Comply or Defect in Component | Part 21/50.55 - Ap1000 Updated Reactor Coolant Pump Locked Rotor Analysis | The following was received via facsimile: The purpose of this letter is to provide the Commission with the prescribed interim report as required per 10 CFR 21.21(a)(2) of a deviation identified by Westinghouse Electric Company LLC. This also will serve as an interim report under 10 CFR 50.55 (3)(ii) to the extent applicable. A postulated reactor coolant pump (RCP) locked rotor (LR) transient has been explicitly analyzed for the AP1000 steam generator (SG) structural design, as documented in the latest AP1000 Design Control Document (DCD), Revision 19. This includes the calculation of LR hydrodynamic forces (HF) on the SG using the BANG UP code. This activity was performed based upon the unique features of the AP1000 design. However, the other AP1000 reactor coolant system (RCS) structural component analyses have not considered the locked rotor transient for hydrodynamic forces, even though a determination has been made that the effects of these loads could be more bounding than the limiting design-basis loss of coolant accident (LOCA) hydrodynamic forces (based on the BANG UP calculation of pressure pulsations through the RCS). Westinghouse has not yet completed its evaluation as to whether there is a reportable condition as defined in 10 CFR 21 (or 10 CFR 50.55 to the extent applicable) if the deviation is left uncorrected. Westinghouse expects to complete this evaluation by September 30, 2014. We will inform the staff if there are any changes to this schedule, prior to that date. | Steam Generator Reactor Coolant System | |
| ENS 49083 | 31 May 2013 04:00:00 | 10 CFR 21.21(a)(2), Interim Report for Comply or Defect in Component | Part-21 Interim Report - Incorrect Pressurizer Support Loads for Ap1000 | The deviation being evaluated is an identified inconsistency between the applied design loads for the AP1000 plant pressurizer support columns and embedments and the calculated actual loads. As a result, certified for construction drawings have been delivered to customers of the AP 1000 plant new build projects with an incorrect pressurizer support column embedment design configuration. The planned changes to the embedments to correct this deviation for the pressurizer support columns will be reflected on revised certified for construction drawings but do not require changes to the current licensing basis. The certified for construction drawings have been delivered to U.S. AP1000 plant new build customers, V.C. Summer Units 2 and 3, and A.W. Vogtle Units 3 and 4. |