ML18144A693
| ML18144A693 | |
| Person / Time | |
|---|---|
| Site: | Peach Bottom  |
| Issue date: | 05/31/2018 |
| From: | Minnick S Exelon Generation Co |
| To: | Jennifer Tobin Division of Operating Reactor Licensing |
| Tobin J, NRR/DORL/LPL1, 415-2328 | |
| References | |
| Download: ML18144A693 (19) | |
Text
Peach Bottom Atomic Power Station Units 2 and 3 License Amendment Request for Expanded Actions for LEFM Flow Meter Conditions NRC Pre-Submittal Meeting May 31, 2018
Introductions
Purpose and Agenda Steve Minnick
Attendees Steve Minnick - MUR Senior Project Manager Exelon Chris Weichler - Senior Manager, Operations Exelon Michael Lewis - LEFM System Engineer Exelon David Neff - Principal Regulatory Engineer Exelon Kelly Hamm - Senior Engineer Exelon 2
Purpose Brief the NRC on a proposed PBAPS License Amendment Request to expand the number of Intermediate Power Levels from 1 to 4 when the LEFMs are not in CheckPlus (NORMAL) Mode 3
Agenda PBAPS Station Overview (Chris Weichler)
PBAPS LEFM System Overview (Mike Lewis)
LEFM License Amendment Request (Dave Neff)
Proposed Compensatory Measures (Chris Weichler)
Uncertainty Calculation Approach (Kelly Hamm)
Summary (Chris Weichler) 4
Station Overview General Electric BWR-4, Mark I Containment Containment design pressure 56 psig Began commercial operation in 1974, OLTP 3293 MWt Extended Power Uprate in 2015 to 3951 MWt 24-month operating cycle GNF2 full core Licensed for Increased Core Flow (ICF) (110%) and MELLLA+
Caldon (Cameron) CheckPlus Leading Edge Flow Meter (LEFM) currently installed on Units 2 and 3 - Three FW lines Current Licensed Thermal Power 4016 MWt w/MUR Uprate
& Intermediate Power Level for LEFM Check Mode condition 5
Background
- EPU in 2015 did not incorporate MUR based on LEFM for simplicity of the LAR and NRC review. LEFMs continued to be primary means for FW flow measurement
- MUR Uprate (1.66%) NRC approved in 2017 included one intermediate power level with one or more LEFM(s) in Check Mode 6
PBAPS LEFM System PBAPS LEFM CheckPlus Schematic Schematic Showing One Plane Check Mode Schematic Showing Two Planes CheckPlus Mode 7
PBAPS LEFM System -Modes Individual FW line LEFM Modes Operating Conditions CheckPlus (NORMAL) - Both planes of the LEFM are fully functional Check (MAINTENANCE) - One plane of LEFM is not operable and flow measurement provided by operable plane FW flow measurement accuracy CheckPlus (NORMAL) > Check (MAINTENANCE) > Venturi Inoperable Condition FAIL mode - Both planes of LEFM inoperable Flow measurement switched to Venturi (Venturi Mode) 8
Summary of License Amendment Request PBAPS proposes to expand the number of Intermediate Power Levels from 1 to 4 when the LEFMs are not in CheckPlus Mode LEFM and Venturi uncertainties based on NRC-approved Cameron Topical Report and industry-standard method for statistical based uncertainty calculations LAR will address Simple Decision Making, Conservative Plant Operation, and Uncertainty Calculation Conservatism If approved, the changes will be incorporated into a revision to the Technical Requirements Manual (TRM)
The Intermediate Power Level for each condition is based on the Total Power Uncertainty (TPU) for the LEFM conditions for each FW line 9
Proposed LEFM Expanded Actions 10 LEFM OPERATING CONDITIONS Maximum Power Level (MWt)
Current Proposed All LEFMs in CheckPlus Mode 4016 4016 One LEFM in Check Mode and Two LEFMs in CheckPlus Mode 4010 4015 Two LEFMs in Check Mode and One in CheckPlus Mode 4013 Three LEFMs in Check Mode 4010 One LEFM in Venturi Mode and other LEFMs in CheckPlus or Check Mode 3951 3982 Two or three LEFMs in Venturi Mode 3951
Reasons for Requested Change Repair Requires Shutdown to Restore LEFM to CheckPlus Mode
- LEFM spool pieces are located in High Radiation Area (3 R/hr dose rate field in steam tunnel) and acoustic transducers/cabling are inaccessible for repair
- Power reduction of 65 MWt required until shutdown if one LEFM fails to Venturi Mode and cannot be restored in 72 hrs Optimization of Available Instrumentation Accuracy
- Propose to take credit for greater accuracy of the other two LEFMs when one FW line is in Venturi Mode
- Propose to take credit for greater accuracy of the LEFMs when one or two are in the CheckPlus Mode with none in Venturi Mode
- Power reduction of 6 MWt required until shutdown if > 1 LEFMs are in Check Mode and cannot be restored in 72 hrs 11
Regulatory Screening LEFM and TPU calculation methodology is consistent with the NRC-approved methodology in Cameron Topical Report ER-157P-A, Rev 8 NRC-approved topical reports do not consider use of a FW venturi for the TPU calculations Proposed compensatory measures and Intermediate Power Levels are based on updated uncertainty analyses that are expansion to the 2017 MUR Amendment Our review concluded prior NRC approval is required per 10 CFR 50.59 12
Simple and Conservative Implementation The LAR will address
- Expanded TRM Conditions, Compensatory Actions and Completion times
- Bases for Simple Decision Making and Conservative Plant Operation, and
- Bases for and Conservatisms in TPU Calculation Approach 13
Simple Decision Making More than 15 years of procedure experience and training in responding to LEFM(s) in Check Mode, failures and restoration to CheckPlus Mode LEFMs have been in-service for Core Thermal Power calculation since 2002 LEFM status is continuously monitored with alarms in the Main Control Room Sufficient time for operators to recognize and take necessary actions when LEFM(s) change from CheckPlus Mode 14
Conservative Plant Operation FW venturi flow measurement instrument loop calibrated every refueling outage LEFM/Venturi flow comparisons are monitored daily and trended Procedures require that a venturi be calibrated to its associated LEFM using data from the 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> prior to the time the LEFM went into Check or Venturi Mode, or was removed from service If it is not possible to calibrate a venturi to its associated LEFM, Core Power is reduced to its Required Intermediate Power Level after a period of 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />, rather than after the Required Compensatory Measure Completion Time of 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> 15
MAIN CONTROL ROOM INDICATIONS PBAPB LAR for LEFM Conditions 16
Uncertainty Calculation Approach LEFM FW Flowrate uncertainties and Total Thermal Power uncertainties are calculated using the same methodology as for the MUR LAR and the Cameron Topical Report ER-157P-A, Rev 8 Venturi Flowrate measurement error was determined using ASME PTC-6 Report. Venturi measurement loop uncertainties are calculated in accordance with the approved Exelon Setpoint Methodology Total thermal power uncertainty results for a given condition from the more conservative unit are applied generically to both units Calculations use conservative values and assumptions as compared to actual plant data 17
Summary 15 years of experience with LEFM system and TRM Requirements Conservative calculations consistent with NRC-approved topical report and industry standards Operators monitor LEFM and venturi flow measurements in live time 18
Questions?
19