ML102780662
| ML102780662 | |
| Person / Time | |
|---|---|
| Site: | Point Beach  |
| Issue date: | 10/04/2010 |
| From: | Beltz T Plant Licensing Branch III |
| To: | Jim Costedio Point Beach |
| beltz T, NRR/DORL/LPL3-1, 301-415-3049 | |
| Shared Package | |
| ML102780672 | List: |
| References | |
| TAC ME4006, TAC ME4007 | |
| Download: ML102780662 (2) | |
Text
REQUESTS FOR ADDITIONAL INFORMATION POINT BEACH NUCLEAR PLANT, UNITS 1 AND 2 LICENSE NOS. DPR-24 AND DPR-27 LICENSE AMENDMENT REQUEST REACTOR VESSEL HEAD DROP ANALYSIS METHODOLOGY REVISION TAC NOS. ME4006 AND ME4007 EMCB RAI 1 As described in Section 4.3 of Enclosure 2 to Reference 2, bottom mounted instrumentation (BMI) conduits 32 and 29 are the only conduits modeled in the ANSYS analyses used to support the conclusion in this license amendment request (LAR) that the BMI conduits will maintain their structural integrity under a postulated reactor vessel head (RVH) drop. While it is recognized by the NRC staff that BMI conduits 32 and 29 geometrically bound the other conduits (i.e., they are the shortest and longest conduits, respectively), no information was provided which indicates that there would be no adverse affects on these conduits due to the structural interactions with the other 34 conduits attached to the reactor vessel. By analyzing conduits 32 and 29 individually, other interactions between the 34 conduits absent in the analyses may not be adequately accounted for in the present structural analyses.
Please provide quantitative justification which demonstrates that modeling only these two conduits, without loads resulting from possible interactions from adjacent conduits, provides a bounding structural evaluation.
EMCB RAI 2 Section 4.6 of Enclosure 2 to Reference 2 indicates that the material data used as an input to the ANSYS model used to demonstrate the structural integrity of the BMI conduits is based on true stress-strain data. The guidance found in NUREG-0612, Control of Heavy Loads at Nuclear Power Plants, and in Section 2.3.2 of Nuclear Energy Institute (NEI) Report 08-05, Industry Initiative on Control of Heavy Loads, stipulates that the use of true stress-strain data is appropriate for these analyses. However, the construction of true stress-strain curves used in these analyses can be based on a number of factors; these are also discussed in Section 2.3.2 of NEI 08-05.
Please address the following items regarding the true stress-strain curve used for the Point Beach Nuclear Plant (PBNP) RVH drop methodology LAR under consideration:
a) A temperature of 70 degrees Fahrenheit has been assumed to develop the true stress-strain data curve for the material model.
Please provide justification for the use of this temperature as it relates to actual operating parameters when the accident is assumed to occur.
b) Table 4-1 of Enclosure 2 in Reference 2 indicates that the data points used to construct the true stress-strain curve in Figure 4-6 were gathered from Reference 5 of Enclosure 2 (Westinghouse Calculation Note, CN-RCDA-04-46).
Please discuss the methodology used in this calculation to develop these data points.
This discussion should focus on the development of the material model curve and the justification for the use of this model as it relates to the guidance found in NEI 08-05.
c) Please indicate whether a dynamic increase factor (DIF) has been incorporated into the true stress-strain curve found in Figure 4-6 of Enclosure 2 to Reference 1. If a DIF has been applied to the curve, please provide technical justification for the DIF(s) applied to the curve.
d) Please confirm that the curve found in Figure 4-6 is not extrapolated further for the ANSYS analysis and that ultimate failure strain for this model is 0.26 in/in, as indicated in Table 4-1.
REFERENCES
- 1)
Letter from L. Meyer, NextEra Energy Point Beach, LLC, to NRC Document Control Desk, Point Beach Nuclear Plant, Units 1 and 2, Docket Nos. 50-266 and 50-301, Renewed License Numbers DPR-24 and DPR License Amendment Request 265 - Revision to the Reactor Vessel Head Drop Methodology, June 1, 2010 (ADAMS Accession No. ML101520200)
- 2)
Letter from L. Meyer, NextEra Energy Point Beach, LLC, to NRC Document Control Desk, Point Beach Nuclear Plant, Units 1 and 2, Docket Nos. 50-266 and 50-301, Renewed License Numbers DPR-24 and DPR License Amendment Request 265 - Revision to the Reactor Vessel Head Drop Methodology, Supplement 1, July 9, 2010. (ADAMS Accession Nos. ML102030115 (Cover Letter and Enclosure 1) and ML102030116 (Enclosure 2))