Testing of LWR Surveillance Materials from the High Fluence UCSB ATR-2 Irradiation

Journal Article · Wed Jun 15 04:00:00 EDT 2016 · Transactions of the American Nuclear Society

OSTI ID:22992155

Nanstad, Randy; Robertson, Janet; Sokolov, Mikhail L. ^[1]; Odette, G. Robert; Yamamoto, Takuya; Wells, Peter; Almirall, Nathan ^[2]; Server, William S. ^[3]; Hardin, Tim ^[4]; Wilford, Keith; Williams, Tim ^[5]

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1. Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States)
2. Materials Department, University of California, Santa Barbara CA93106 (United States)
3. ATI Consulting Black Mountain, NC 28711 (United States)
4. Electric Power Research Institute, Palo Alto, CA94304 (United States)
5. Rolls-Royce plc (United Kingdom)

The reactor pressure vessel (RPV) in a light water reactor (LWR) represents the first line of defense against a release of radiation in case of an accident. Thus, regulations that govern the operation of commercial nuclear power plants require conservative margins of fracture toughness, both during normal operation and under accident scenarios. In the unirradiated condition, the RPV has sufficient fracture toughness such that failure is implausible under any postulated condition, including pressurized thermal shock (PTS) in pressurized water reactors (PWR). In the irradiated condition, however, the fracture toughness of the RPV may be severely degraded, with the degree of toughness loss dependent on the radiation sensitivity of the materials. Of the many significant issues discussed regarding irradiation effects, the issue considered to have the most impact on the current regulatory process is that associated with effects of neutron irradiation on RPV steels at high fluence, for long irradiation times, and as affected by neutron flux. As also stated in a companion paper by Odette, et. al., the primary objective of the DOE-sponsored Light Water Reactor Sustainability (LWRS) Program RPV task is to develop robust predictions of transition temperature shifts (TTS) at high fluence (φt) to at least 10{sup 20} n/cm{sup 2} (>1 MeV) pertinent to plant operation of some pressurized water reactors (PWR) for 80 full power years. While understanding of copper-enriched precipitates (CRPs) have been fully developed, the discovery and experimental verification of 'late blooming' Mn-Ni-enriched precipitates (MNPs) with little to no copper for nucleation has stimulated research efforts to understand the evolution of these phases. The new and existing databases will be combined to support development of physically based models of TTS for high fluence-low flux (φ < 10 {sup 11}n/cm{sup 2}-s) conditions, beyond the existing surveillance database, to neutron fluences of at least 10{sup 20} n/cm{sup 2} (>1 MeV). The RPV task of the LWRS Program has worked with various organizations to obtain archival surveillance materials from commercial nuclear power plants to allow for comparisons of the irradiation-induced microstructural features from reactor surveillance materials with those from similar alloys irradiated under high flux conditions in test reactors, such as the UCSB ATR-2 experiment conducted at the Advanced Test Reactor (ATR) at the Idaho National Laboratory (INL). (authors)

• OSTI ID: 22992155
• Journal Information: Transactions of the American Nuclear Society, Journal Name: Transactions of the American Nuclear Society Journal Issue: 1 Vol. 114; ISSN 0003-018X
• Country of Publication: United States
• Language: English

Related Subjects

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS
42 ENGINEERING
FRACTURE PROPERTIES
IDAHO NATIONAL LABORATORY
INSPECTION
MANGANESE PHOSPHIDES
MEV RANGE 01-10
NEUTRON FLUX
NUCLEAR POWER PLANTS
PRECIPITATION
PRESSURE VESSELS
PWR TYPE REACTORS
RADIOSENSITIVITY
REGULATIONS
STEELS
TEST REACTORS
TRANSITION TEMPERATURE