ML16253A411

Palo Verde Nuclear Generating Station Generic Letter 2004-02 - September 7, 2016

ML16253A411
Person / Time
Site:	Palo Verde
Issue date:	09/07/2016
From:	Dilorenzo M Arizona Public Service Co
To:	Office of Nuclear Reactor Regulation
Lingam S P
References
CAC MF4702, CAC MF4703, CAC MF4704, GL-04-002
Download: ML16253A411 (12)

Text

Palo Verde Nuclear Generating Station Generic Letter 2004-02 September 7, 2016 Mike Dilorenzo Department Leader Nuclear Regulatory Affairs Agenda Introductions Background Overview of Results Plant Configuration Results of Analysis Path Forward 2 Background 12/18/2013 - APS submitted Revision 2 to Supplemental Response to NRC Generic Letter 2004-02 (Option 2A) 4/15/2015 - Condition Report 15-01860 documents that APS failed to identify and evaluate Microtherm on the Reactor Vessel 6/10/2015 - Initial Public Meeting with NRC 8/26/2015 - Follow up Public Meeting with NRC 12/17/2015 - Follow up Public Meeting with NRC 4/30/2016 - Unit 1 Inspections 3 Overview of Results Palo Verde remains a "low fiber plant" Transported fiber quantities from D-ring and RPV nozzle breaks are within the amounts used in Palo Verde head loss testing Analyzed Microtherm Impact NPSH and structural limits are satisfied (based on comparative analysis) Open surface area precludes typical high headloss impact of Microtherm on fiber beds Analyzed Temp-Mat Impact Fines assumed to transport Low flow velocity / vertical flow path inhibits small & large piece transport Open surface area remains NPSH and structural limits are satisfied (based on comparative analysis) 4 5 Microtherm Locations Plant Configuration Temp-Mat Plant Configuration Original Limiting Break Location Steam Generator Hot Leg Nozzle Reactor Pressure Vessel (RPV) Hot Leg Nozzle Break Location 6 Plant Configuration 7 LOCATION Unit 1 Unit 2 Unit 3 Planned Disposition RPV (Microtherm & Temp-Mat) X X X Addendum RPV Cavity (Microtherm & Temp-Mat) X X X Addendum RPV ICIs (Temp-Mat) X X X Addendum Feedwater / SDC Lines (Nukon) Comp 2017 2016 Remove Cold Leg 1A, 1B, 2A, 2B RTD (Temp-Mat) Comp Comp 2016 Remove Crossover 10A, 1B, 2A, 2B RCP & SG Nozzles (Temp-Mat) N/A N/A 2016 Remove Cold Leg 1A, 1B, 2A, 2B RPV Elbow (Temp-Mat) N/A N/A 2016 Remove RCP Stops 1A, 1B, 2A, 2B (Temp-Mat) N/A N/A 2016 Remove Results of Analysis Debris Generation -Microtherm zone of influence (ZOI) based on robustness of encapsulation -Temp-Mat ZOI is from NEI 04-07 Safety Evaluation -RPV nozzle break debris quantity estimates account for restrained separation of pipe at RPV nozzle breaks - Utilizing information from BWR Owners Group Utility Resolution Guidance Debris Transport -RPV nozzles breaks All destroyed Microtherm is considered to transport to the strainer All Temp-Mat Fines, including from erosion, are considered to transport from Reactor Cavity to strainers Small and large Temp-Mat pieces generated in the Reactor Cavity will not transport to strainers based on turbulent kinetic energy and low flow velocity in upward vertical flow path of 24 to 42 feet (for all flow scenarios) 8 Results of Analysis (cont) Chemical Effects Load -Estimated using WCAP-16530-NP spreadsheet -Palo Verde test used higher loads than required by analysis of record -Salem U2 Test 6 (S2T6) used in comparative analyses for headloss D-ring break -Normalized load (lbm/ft2) is under 70% of test of record and less than 55% of S2T6 RPV nozzle breaks -Normalized load (lbm/ft2) is slightly under (98% of) test of record and less than 80% of S2T6 9 Results of Analysis (cont) Head Loss / NPSH -Comparative analysis with S2T6 indicates Palo Verde NPSH and structural limits are not challenged S2T6 fiber, particulate, Min-K and chemical effects loads bound Palo Verde with Microtherm debris quantities S2T6 had no open area - fully developed debris bed with a thickness of 0.3 inches Palo Verde retains open screen area Differences in approach velocities compensated by open strainer area Updated strainer structural capacity, based on ASME NF analysis and allowable stress limits, results in minimum headloss margin of 2.2 ft-water for governing break 10 Summary Analysis of both the original D-ring break location and the RPV nozzle break cases have favorable results Fiber inspection & removal will continue for the following outages -Unit 3R19 (Fall 2016) -Unit 2R20 (Spring 2017) -Unit 1R20 (Fall 2017) -Unit 3R20 (Spring 2018) -Unit 2R21 (Fall 2018) -Unit 1R21 (Spring 2019) Addendum to the Supplemental APS Response to GL 2004-02 (November 2016) 11 12 We SAFELY and efficiently generate electricity for the long term