ML101810576
| ML101810576 | |
| Person / Time | |
|---|---|
| Site: | Point Beach  |
| Issue date: | 06/28/2010 |
| From: | Division of Operating Reactor Licensing |
| To: | Nextera Energy |
| beltz T, NRR/DORL/LPL3-1, 301-415-3049 | |
| Shared Package | |
| ml101810585 | List: |
| References | |
| TAC ME4006, TAC ME4007 | |
| Download: ML101810576 (2) | |
Text
Point Beach Nuclear Plant, Units 1 and 2 License Amendment Request to Revise the Reactor Vessel Head Drop Methodology Request for Supplemental Information to Support Acceptance Review TAC Nos. ME4006 and ME4007 In accordance with the second criterion of Section 3.1.2 of Appendix B in NRR Office Instruction, LIC-109, Guide for Performing Acceptance Reviews - Technical Staff Criteria, the staff of the Mechanical and Civil Engineering Branch (EMCB) has determined that insufficient information has been provided by the licensee with regards to their requested licensing action (RLA). These insufficiencies, which are detailed below, would result in an inappropriately large number of RAIs. However, based on the statements in the license amendment request (LAR),
the supplemental information necessary for the NRC staff to review the RLA appears readily available to the licensee. Therefore, the NRC staff considers the RLA unacceptable for review with opportunity to supplement, in accordance with LIC-109. The RLA would amend the current operating licenses at Point Beach Nuclear Plant, Units 1 and 2, to revise the current reactor vessel head drop analysis methodology.
EMCB Supplemental Information Request 1 The license amendment request submitted by Point Beach relies solely on the results of a finite element analysis (FEA) performed using the commercial FEA program, ANSYS, which demonstrated that the two bottom-mounted instrument (BMI) conduits reviewed did not rupture.
However, the licensee provided insufficient information regarding the ANSYS analyses, in order for the NRC staff to assess the validity of the analyses, as incorrect results can be produced by FEA models which have not been properly developed. The following information regarding the ANSYS analyses should be provided, in summary form, with appropriate assumptions and justifications:
Contour plots graphically summarizing the FEA results.
True stress-strain material data curves used in the FEA.
Element types used in the FEA models.
Boundary conditions utilized in the model (see Supplemental Information Request 2).
Preprocessor graphics displaying these pertinent details (locations and details of degrees of freedom (DOF), boundary conditions, mesh density, etc.).
Results of any mesh convergence studies performed to demonstrate satisfactory model responses.
Plot comparison of the spring-mass system input displacement time-histories versus the output displacement time-histories.
General information on the type of analyses performed (i.e., confirmation that inelastic analysis was performed).
EMCB Supplemental Information Request 2 No information was provided regarding the structural integrity of the BMI conduit supports.
Information should be provided regarding the behavior of these supports during the vessel head drop transient as it relates to the structural behavior of the supports during this transient.
Depending on this behavior (i.e., whether the supports fail, deform, or retain elastic behavior),
information should be provided indicating whether the finite element analyses are correctly configured to capture the boundary conditions resulting from the stability of the supports.
Additionally, a summary of the results of the stresses found in the analysis of the conduit supports, compared with the acceptance criteria for the support stresses, should be provided.