ML16274A001

PWR MSIP Analysis and Measurements

ML16274A001
Person / Time
Site:	Calvert Cliffs
Issue date:	09/30/2016
From:	Benson M L, Raynaud P A, Rudland D L NRC/RES/DE
To:
David Rudland
References
Download: ML16274A001 (10)

Text

PWR MSIP Analysis and MeasurementsDavid L. Rudland, Mike Benson and Patrick RaynaudOffice of Nuclear Regulatory ResearchDivision of EngineeringU.S.NRCMeeting On Mechanical Stress Improvement Processes And The Calvert Cliffs ExperienceWednesday, September 28, 2016 2160578193 PWR MSIPIn 2007-8, RES responded to an NRR request to

-Develop criteria for evaluating the effectiveness of proposed Stress Improvement (MSIP) processes in producing compressive residual stresses and assistance in confirming appropriate changes in inspection frequency that may accompany application of effective Stress Improvementprocesses.RES developed plan, conducted numerical analyses, and conducted experiments to meet the needRES confirmed the efficacy of the MSIP approach 2 PWR MSIP Numerical StudiesResults summarized in

-Battelle report, "Evaluation of the mechanical stress improvement process (MSIP) as a mitigation strategy for primary water stress corrosion cracking in pressurized water reactors," ML092990638Investigated three geometries

-Hot Leg-Pressurizer Surge

-Pressurizer Safety Nozzle 3 PWR MSIP Numerical Studies 4All axi-symmetric analyses on pipeModelled both welds and MSIP Conducted a variety of sensitivity analysesConducted numerical flaw analyses PWR MSIP Sample Results 5Safety Nozzle GeometryHoop StressAxial Stress PWR MSIP Strain MeasurementsResults summarized in

-PNNL report, "Surge Nozzle NDE Specimen Mechanical Stress Improvement Analysis," ML111960318Pressurizer Surge NozzleSome difficulty was encountered in calculating stresses from strain due to plasticity

-Predictions were reasonable 6

PWR MSIP Strain Measurements 7Strain gage locationNumerical analysesComparison PWR MSIP UT MeasurementsResults Summarized in

-PNNL report, "Surge Nozzle NDE Specimen Mechanical Stress Improvement Analysis," ML113010152Ignalina(shop and field SS welds) and Pressurizer surge (from strain gage study)Service induced IGSCC and implanted flaws 8 PWR MSIP UT Measurement 9The INPP data displayed a significant reduction in flaw length and amplitude after MSIP application and one flaw had become transparent to ultrasound The surge line specimen showed almost no change in length or depth after MSIP -attributed to initial stress state and implanted flaw misalignment1.5 MHz, Line Scan Data after MSIP PWR MSIP Summary ReportsAssessment of MSIP:-A PNNL Report, "Assessment of the Mechanical Stress Improvement Process for Mitigating Primary Water Stress Corrosion Cracking in Nickel Alloy Butt Welds in Piping Systems Approved for Leak-Before-Break," ML13330A972

-Uses previous work to draw conclusions on efficacy of MSIP and assesses inspection intervals per CC N770 PWSCC Mitigation

-NUREG/CR-7187 -Managing PWSCC in Butt Welds by Mitigation and Inspection10