ML16313A466
| ML16313A466 | |
| Person / Time | |
|---|---|
| Site: | Watts Bar  |
| Issue date: | 11/09/2016 |
| From: | Tennessee Valley Authority |
| To: | Robert Schaaf Plant Licensing Branch II |
| Schaaf R, DORL/LPLII-2, 301-415-6020 | |
| References | |
| Download: ML16313A466 (15) | |
Text
Watts Bar Nuclear Plant Unit 2 Ice Weight Technical Specification Change November 9, 2016
Agenda Watts Bar Nuclear Plant - Unit 2 Ice Weight Technical Specification Change l 2
- Introductions / Opening Remarks
- Background
- Intent
- Technical Basis
- Schedule
- Closing Remarks
Watts Bar Nuclear Plant - Unit 2 Ice Weight Technical Specification Change l 3 Opening Remarks
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Background===
Tech Spec SR 3.6.11.2 Specific to ice condenser containments Verifies sufficient ice mass to mitigate LOCA/MSLB accidents Different value for each Watts Bar unit Watts Bar Nuclear Plant - Unit 2 Ice Weight Technical Specification Change l 4 Tech Spec Required Ice Mass Unit 1 2,404,500 lbm Unit 2 2,750,700 lbm
Background (continued)
Difference Unit 1 Originally licensed with WCAP-10325-P-A, Westinghouse LOCA Mass and Energy (M&E)
Release Model for Containment Design (circa 1983)
NRC Amendment 62 dated 7/25/2006 approved the increase in the ice mass to 2,404,500 lbm due to the additional energy associated with the replacement steam generators based on WCAP-10325-P-A Adopted WCAP-17721-P-A (WCOBRA/TRAC) as Analysis of Record (AOR) in 2015 Addressed NSAL-11-5 and other methodology issues Results demonstrated containment pressure was significantly below design pressure Analysis did not require a change to the Unit 1 ice mass Unit 2 Analysis was already under staff review prior to WCAP-17721-P-A approval Licensed WCAP-10325-P-A as AOR Model was based on Unit 2 (Model D3 steam generators)
Methodology issues could be absorbed in initial ice load Simplified initial licensing of Unit 2 Watts Bar Nuclear Plant - Unit 2 Ice Weight Technical Specification Change l 5
Intent Apply the current Unit 1 (WCOBRA/TRAC) analysis documented in Engineering Report WCAP-17834-P (ML15254A564) to Unit 2 Aligns the Unit 2 Tech Spec SR 3.6.11.2 to match Unit 1 value Achieves roughly 350,000 lbm reduction in required ice weight TVA would like to apply the revised ice mass for Unit 2 during the first refueling outage in October 2017 in order to align maintenance activities for both units See proposed Tech Spec changes on following slide Watts Bar Nuclear Plant - Unit 2 Ice Weight Technical Specification Change l 6
Proposed Tech Spec Changes Revises SR 3.6.11.2 to reduce the Tech Spec required total ice mass Revises SR 3.6.11.3 to reduce the average ice weight in the sample baskets Watts Bar Nuclear Plant - Unit 2 Ice Weight Technical Specification Change l 7
Proposed Tech Spec Bases Changes Revises Bases 3.6.11 to reduce the Tech Spec required total ice mass Watts Bar Nuclear Plant - Unit 2 Ice Weight Technical Specification Change l 8
Proposed Tech Spec Bases Changes Revises SR 3.6.11.2 bases to reduce the average ice weight in the sample baskets Watts Bar Nuclear Plant - Unit 2 Ice Weight Technical Specification Change l 9
Technical Basis Westinghouse Evaluation Westinghouse performed a full-spectrum review Demonstrates that Watts Bar Unit 1 bounds Unit 2 from a LOCA M&E /
Containment Integrity perspective Unit 1 and Unit 2 share many common NSSS design features (reactor, fuel, loop configuration, containment design)
Unit 1 bounds Unit 2 for a key design feature Unit 1 replacement steam generator primary volume is larger than the Unit 2 original steam generators (approximately 1,038 ft3 total NSSS volume)
Replacement steam generators contain more stored metal energy (approximately 224,000 lb total NSSS mass)
Watts Bar Nuclear Plant - Unit 2 Ice Weight Technical Specification Change l 10
WEC LOCA M&E and Containment Integrity Evaluation Westinghouse has determined that the current Watts Bar Unit 1 AOR is bounding relative to Unit 2 Containment peak pressure is a function of containment design and mass and energy releases Evaluation has shown that the containment design is virtually identical (e.g. heat slabs, containment cooling functions)
RCS designs are virtually identical, with the exception of the steam generator design The current M&Es calculated with the model 68AXP steam generator design would bound M&Es calculated with the model D3 Results of this evaluation will be provided with TVA submittal Watts Bar Nuclear Plant - Unit 2 Ice Weight Technical Specification Change l 11
Schedule Watts Bar Nuclear Plant - Unit 2 Ice Weight Technical Specification Change l 12 Date Milestone Late Nov 2016 Westinghouse completes reconciliation analysis Mid-Dec 2016 TVA submits License Amendment Request Mid-Jan 2017 Post-Submittal follow-up discussion Sept 2017 NRC issues SER Oct 2017 Unit 2 refueling outage begins
Watts Bar Nuclear Plant - Unit 2 Ice Weight Technical Specification Change l 13 Closing Remarks
Questions?