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On High-Fluence Irradiation Hardening of Nine RPV Surveillance Steels in the UCSB ATR-2 Experiment: Implications for Extended-Life Embrittlement Predictions

Conference ·
 [1];  [2];  [2];  [3];  [4];  [5];  [2]
  1. R&S Consulting
  2. UCSB
  3. ATI Consulting, Pinehurst, NC
  4. ORNL
  5. Electric Power Research Institute (EPRI)
+ Show Author Affiliations

Nine archival reactor pressure vessel (RPV) surveillance steels from commercial nuclear power plants were irradiated in the University of California, Santa Barbara Advanced Test Reactor 2 (ATR-2) experiment to evaluate irradiation embrittlement under low-flux surveillance capsule versus higher flux test reactor (ATR-2) conditions. The postirradiation measurements of irradiation hardening, measured as increases in yield stress (Δσy), and corresponding conversions of Δσy to Charpy V-notch 41-J transition temperature shifts (ΔTc) are compared with various embrittlement trend curve (ETC) model predictions for the nine steels. Tensile and converted shear punch and microhardness measurements of Δσy generally show a continuing increase between intermediate and high ATR-2 fluences. The Eason-Odette-Nanstad-Yamamoto and ASTM E900 ETC models underpredict embrittlement at the ATR-2 irradiation condition: irradiation temperature (Ti) of 292°C, neutron fluence (ϕt) of 1.4 × 1020 n/cm2 (E > 1 MeV), and neutron flux (ϕ) of 3.68 × 1012 n/cm2-s. On average, the French FIS and Japanese JAEC ETCs slightly overpredict the ATR-2 data. The increase in Δσy with higher fluence is primarily due to Ni-Mn-Si precipitates, which slowly evolve in both nearly copper-free and copper-bearing steels. Finally, a new Odette-Wells-Almirall-Yamamoto embrittlement model is shown that yields good predictions for the nine steels at high fluences (ϕt > 5.5 × 1019 n/cm2).

Research Organization:
Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
Sponsoring Organization:
USDOE
DOE Contract Number:
AC05-00OR22725
OSTI ID:
1997806
Resource Relation:
Conference: Radiation Embrittlement Trend Curves/Equations and Their Use for RPV Integrity Evaluations - Prague, , Czech Republic - 4/19/2022 4:00:00 AM-4/22/2022 4:00:00 AM
Country of Publication:
United States
Language:
English

References (10)

Effects of ATR-2 Irradiation to High Fluence on Nine RPV Surveillance Materials report May 2017
A universal relationship between indentation hardness and flow stress journal August 2007
The hardness of solids journal January 1970
Relationship Between Irradiation Hardening and Embrittlement of Pressure Vessel Steels preprint February 2018
A Physically Based Correlation of Irradiation-Induced Transition Temperature Shifts for RPV Steels report November 2007
Revision of the irradiation embrittlement correlation used for the EDF RPV fleet journal January 2011
Contribution of irradiation-induced defects to hardening of a low-copper reactor pressure vessel steel journal August 2018
Microstructural behavior of VVER-440 reactor pressure vessel steels under irradiation to neutron fluences beyond the design operation period journal June 2005
On the correlation between irradiation-induced microstructural features and the hardening of reactor pressure vessel steels journal November 2010
Fluence rate effects on irradiation embrittlement of model alloys journal May 2005

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