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Title: Nonlinear Ultrasonic Techniques to Monitor Radiation Damage in RPV and Internal Components

The objective of this research is to demonstrate that nonlinear ultrasonics (NLU) can be used to directly and quantitatively measure the remaining life in radiation damaged reactor pressure vessel (RPV) and internal components. Specific damage types to be monitored are irradiation embrittlement and irradiation assisted stress corrosion cracking (IASCC). Our vision is to develop a technique that allows operators to assess damage by making a limited number of NLU measurements in strategically selected critical reactor components during regularly scheduled outages. This measured data can then be used to determine the current condition of these key components, from which remaining useful life can be predicted. Methods to unambiguously characterize radiation related damage in reactor internals and RPVs remain elusive. NLU technology has demonstrated great potential to be used as a material sensor – a sensor that can continuously monitor a material’s damage state. The physical effect being monitored by NLU is the generation of higher harmonic frequencies in an initially monochromatic ultrasonic wave. The degree of nonlinearity is quantified with the acoustic nonlinearity parameter, β, which is an absolute, measurable material constant. Recent research has demonstrated that nonlinear ultrasound can be used to characterize material state and changes in microscale characteristicsmore » such as internal stress states, precipitate formation and dislocation densities. Radiation damage reduces the fracture toughness of RPV steels and internals, and can leave them susceptible to IASCC, which may in turn limit the lifetimes of some operating reactors. The ability to characterize radiation damage in the RPV and internals will enable nuclear operators to set operation time thresholds for vessels and prescribe and schedule replacement activities for core internals. Such a capability will allow a more clear definition of reactor safety margins. The research consists of three tasks: (1) materials sensing and monitoring; (2) physics-based materials and damage evolution modeling; and (3) remaining life estimation by integrating sensing, modeling and uncertainty.« less
Authors:
 [1] ;  [1] ;  [2] ;  [3] ;  [4]
  1. Georgia Inst. of Technology, Atlanta, GA (United States)
  2. Northwestern Univ., Evanston, IL (United States)
  3. Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
  4. Electric Power Research Inst. (EPRI), Knoxville, TN (United States)
Publication Date:
OSTI Identifier:
1227268
Report Number(s):
DOE/NEUP--12-3306
12-3306; TRN: US1500909
DOE Contract Number:
AC07-05ID14517
Resource Type:
Technical Report
Research Org:
Georgia Tech Research Corporation (United States)
Sponsoring Org:
USDOE Office of Nuclear Energy (NE). Nuclear Energy University Programs
Country of Publication:
United States
Language:
English
Subject:
21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS; REACTOR INTERNALS; SERVICE LIFE; NONLINEAR PROBLEMS; PRESSURE VESSELS; STEELS; ULTRASONIC WAVES; CRACKS; DISLOCATIONS; PHYSICAL RADIATION EFFECTS; STRESS CORROSION; FRACTURE PROPERTIES; REACTOR SAFETY; RESIDUAL STRESSES; IRRADIATION; PRECIPITATION; SCHEDULES; SIMULATION; EMBRITTLEMENT; TIME DEPENDENCE; MONITORING; OUTAGES; HARMONICS