ML13133A249: Difference between revisions
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Revision as of 12:51, 30 March 2018
ML13133A249 | |
Person / Time | |
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Site: | Seabrook ![]() |
Issue date: | 05/29/2013 |
From: | NextEra Energy Seabrook |
To: | Lamb J G Plant Licensing Branch 1 |
Lamb J G | |
Shared Package | |
ML13133A158 | List: |
References | |
TAC MF1491 | |
Download: ML13133A249 (24) | |
Text
Fixed Incore Detector Methodology Supplement Presentation to Nuclear Regulatory Commission May 9, 2013 2 FPL/NextEra Representatives Paul Gurney -Reactor Engineering Supervisor, Seabrook Station Michael O'Keefe -Licensing Manager, Seabrook Station Carl O'Farrill -Core Design Manager, FPL Juno Beach Glen Seeburger -Advisory Engineer, AREVA Lynchburg 3 Fixed Incore Detector Methodology Supplement Overview -Seabrook Fixed Incore Detector System (FIDS) Overview of fixed incore detectors -License Amendment Basis Initial licensing through current status - License Amendment Overview Topical report to supplement initial licensing Addresses changes to detector processing Implementation 4 Seabrook Fixed Incore Detector System Seabrook Station -4 loop Westinghouse NSSS -Rated for 3648 MWt Combination fixed and moveable incore detector system for measuring core power distribution -Use of a fixed incore detector system is unique for operating Westinghouse designed reactors 5 Seabrook Fixed Incore Detector System 58 combination fixed and moveable incore detector assemblies Mechanical and electrical connections for each assembly are located at the seal table Each original assembly contains a moveable incore detector path Replacement assemblies do not have a moveable incore detector path 6 Seabrook Fixed Incore Detector System The fixed incore detectors use a platinum emitter -For fixed incore detector applications platinum is unique Most fixed detector applications use a rhodium emitter -Platinum is largely gamma sensitive Some sensitivity to neutrons -Platinum is a long life emitter 7 Seabrook Fixed Incore Detector System 8 License Amendment Basis Initial FIDS Licensing Background -License Amendment Request (LAR) to utilize FIDS for core power distribution monitoring submitted November 1992 -Technical basis for methodology documented in topical report YAEC-1855P Seabrook Station Unit 1 Fixed Incore Detector System Analysis -Validation of FIDS methodology was good agreement between fixed and moveable flux maps obtained in cycles 1 & 2 9 License Amendment Basis NRC Issued License Amendment 27 in December 1993 Conditional acceptance of FIDS for power distribution monitoring -Additional flux maps required in cycles 3 & 4 -Required a follow-up report documenting continued consistency of results Follow-up report YAEC-1931 submitted in March of 1996 -Demonstrated continued acceptability of the FIDS methodology FIDS used for flux mapping since cycle 5, December 1995 10 License Amendment Basis Replacement FIDS -Project to replace FIDS initiated in 2006 -Platinum emitters still providing a good signal -Mechanical and electrical connections at the seal table were degrading 11 License Amendment Basis YAEC-1855P does not specifically address replacement detectors Design of a replacement FID was a like-for-like detector which met the concept of the "standard detector" "Standard detector" defined in YAEC-1855P -Detectors corrected for individual detector differences -Detector material and manufacturing differences -Original detectors - surface area ratio 12 License Amendment Basis Additional factors were necessary for replacement detectors to meet the "standard detector" -Manufacturing differences -Platinum purity differences -Pt-195 depletion 13 License Amendment Basis Gamma Correction Factor - GCF -Manufacturing and purity differences -Determined by direct measurement Platinum Depletion Factor - PDF -Accounts for aging differences between original and replacement detectors 14 License Amendment Basis Detector Replacements Extensive post-modification testing -Validate performance of replacement FIDS -Post modification testing completed before using the replacement detectors for power distribution monitoring 15 License Amendment Basis NRC Modification Inspection (Spring 2012) -Questioned the 10CFR50.59 Evaluation for the flux mapping software changes implemented for replacement detectors -A previous change (2002) to the flux mapping software was self-identified as part of this review -Change involved the neutron sensitive component of the detector signal Pt-195 16 License Amendment Basis YAEC 1855P -Neutron component of signal Assumed to be 25% of total signal -Weighted by thermal flux -Increasing measured-to-predicted signal differences observed starting in cycle 6 17 License Amendment Basis Improved prediction of the neutron component of signal Neutron Conversion Factor (NCF) -Based on Predicted gamma signal and neutron reaction rate Measured signal -Provides better estimate of neutron component of the detector signal -Implemented in Cycle 9 (2002) 18 License Amendment Basis Changes were considered input changes -GCF & PDF (for replacement detectors) -NCF (for neutron signal component) -Did not affect the power distribution processing methodology 19 License Amendment Basis Actions Taken Following Inspection -Contracted AREVA to prepare a topical report to address the changes made to the flux mapping software Initial system development by YAEC, now part of AREVA Extensive FIDS operational performance data (15 cycles) used for validation Technically robust, complete and comprehensive validation Detailed data analysis results available to facilitate NRC review 20 License Amendment Overview New COLR reference to be added to Technical Specifications -Topical Report Supplement YAEC-1855P -Replacement Detectors -Neutron conversion factor -Uncertainty Analysis 21 License Amendment Overview Replacement Detectors -Describe the methodology used to incorporate replacement detectors into flux mapping software Gamma Correction Factor Platinum Depletion Factor -"Standard Detector" Relationship to initial licensing basis 22 License Amendment Overview Neutron Conversion Factor -Basis for NCF -Relationship to initial licensing input assumption 25% of detector signal 23 License Amendment Overview Uncertainty Analysis -2 components of the current licensed uncertainty analysis potentially affected Reproducibility for replacement detectors Detector processing uncertainty -Total and integral detector processing -Failed detector analysis to support minimum requirements 24 License Amendment Overview Draft Schedule -Submit amendment - July 2013 -Request approval - May 1, 2014 Supplemental topical report to be added as a COLR reference in Technical Specification section 6.8