ML102440761

Draft RAIs from Srxb EPU License Amendment Request

ML102440761
Person / Time
Site:	Point Beach
Issue date:	08/31/2010
From:	Beltz T Plant Licensing Branch III
To:	Hale S Point Beach
beltz T, NRR/DORL/LPL3-1, 301-415-3049
Shared Package
ML102450184	List: ML102440754 ML102440761
References
TAC ME1044, TAC ME1045
Download: ML102440761 (2)

Text

REQUESTS FOR ADDITIONAL INFORMATION Point Beach Nuclear Plant, Units 1 and 2 Extended Power Uprate (EPU) License Amendment Request (LAR-261)

Reactor Systems Branch (SRXB) Review (TAC Nos. ME1044 and ME1045)

SRXB-1 The steam generator tube rupture (SGTR) margin-to-overfill (MTO) supplemental analysis was performed based on an assertion that operators may not be able to terminate SGTR events within 30 minutes. As asserted by the licensee, no consideration of single failures, or initial condition uncertainties is included. Decay heat values are assumed at nominal values.

In light of these better-estimate assumptions, please quantify the uncertainty associated with the predicted result for margin to overfill.

SRXB-2 If the uncertainty identified in SRXB-1, above, exceeds the SGTR MTO, then please provide information to demonstrate that the steam lines and pressure relief equipment are qualified to pass liquid water. Provide the information referenced in Requirement (3) of the NRC staff SER approving WCAP-10698 regarding the main steam lines and associated supports under water-filled conditions.

SRXB-3 Two better-estimate thermal-hydraulic analyses were described; one evaluated margin to overfill with a minimum RCS temperature and 10-percent tube plugging, while the other supplemented the dose analysis with a maximum RCS temperature and 0-percent tube plugging.

Please provide a summary statement comparing the purposes of these two analyses, and explain how the different initial condition assumptions achieved each intended purpose.

SRXB-4 In light of the extensive evaluations of post-30 minute steam generator tube rupture consequences, it is not clear that the 30 minute break flow termination time is reasonable.

Please provide additional information to confirm that this assumption is based on observed operator capability, or revise the mass release calculations to incorporate a more realistic break flow termination time. Provide the plant-specific information identified in Requirement (1) of the NRC staff SER approving WCAP-10698 regarding assurance that the necessary actions and times can be taken consistent with those assumed in the SGTR analyses.

SRXB-5 For the SGTR analyses, provide a list of systems, components and instruments that are credited for accident mitigation in the plant specific SGTR EOPs. Specify whether each component is safety grade, consistent with Requirement (4) of the NRC staff SER approving WCAP-10698.

SRXB-6 The EPU analyses represent a significant reduction in safety margin for an event that a large amount of operating experience has shown is not improbable. In light of the fact that the current licensing basis analysis included an overpower margin of nearly 100 MW, a significant conservatism which has been eliminated in the proposed EPU analyses, please justify the continued retention of the no single failure assumption.