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Title: Impact of radiation embrittlement on integrity of pressure vessel supports for two PWR plants

Abstract

Recent data from the HFIR vessel surveillance program indicate a substantial radiation embrittlement rate effect at low irradiation temperatures (/approximately/120/degree/F) for A212-B, A350-LF3, A105-II, and corresponding welds. PWR vessel supports are fabricated of similar materials and are subjected to the same low temperatures and fast neutron fluxes (10/sup 8/ to 10/sup 9/ neutrons/cm/sup 2//center dot/s, E > 1.0 MeV) as those in the HFIR vessel. Thus, the embrittlement rate of these structures may be greater than previously anticipated. A study sponsored by the NRC is under way at ORNL to determine the impact of the rate effect on PWR vessel-support life expectancy. The scope includes the interpretation and application of the HFIR data, a survey of all light-water-reactor vessel support designs, and a structural and fracture-mechanics analysis of the supports for two specific PWR plants of particular interest with regard to a potential for support failure as a result of propagation of flaws. Calculations performed thus far indicate best-estimate critical flaw sizes, corresponding to 32 EFPY, of /approximately/0.2 in. for one plant and /approximately/0.4 in. for the other. These flaw sizes are small enough to be of concern. However, it appears that low-cycle fatigue is not a viable mechanism formore » creation of flaws of this size, and thus, presumably, such flaws would have to exist at the time of fabrication. 59 refs., 128 figs., 49 tabs.« less

Authors:
; ; ;
Publication Date:
Research Org.:
US Nuclear Regulatory Commission (NRC), Washington, DC (United States). Office of Nuclear Regulatory Research; Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
OSTI Identifier:
6371359
Report Number(s):
NUREG/CR-5320; ORNL/TM-10966
ON: TI89007009; TRN: 89-005899
DOE Contract Number:  
AC05-84OR21400
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS; 36 MATERIALS SCIENCE; PRESSURE VESSELS; SUPPORTS; EMBRITTLEMENT; TROJAN REACTOR; TURKEY POINT-3 REACTOR; CRACKS; DATA ANALYSIS; DEFECTS; EXPERIMENTAL DATA; FRACTURES; HFIR REACTOR; MECHANICAL PROPERTIES; NEUTRON FLUX; RADIATION EFFECTS; RECOMMENDATIONS; STRESS ANALYSIS; TEMPERATURE EFFECTS; CONTAINERS; DATA; ENRICHED URANIUM REACTORS; FAILURES; INFORMATION; IRRADIATION REACTORS; ISOTOPE PRODUCTION REACTORS; MECHANICAL STRUCTURES; NUMERICAL DATA; POWER REACTORS; PWR TYPE REACTORS; RADIATION FLUX; REACTORS; RESEARCH AND TEST REACTORS; RESEARCH REACTORS; TANK TYPE REACTORS; TEST REACTORS; THERMAL REACTORS; WATER COOLED REACTORS; WATER MODERATED REACTORS; 210200* - Power Reactors, Nonbreeding, Light-Water Moderated, Nonboiling Water Cooled; 360103 - Metals & Alloys- Mechanical Properties; 360106 - Metals & Alloys- Radiation Effects

Citation Formats

Cheverton, R. D., Pennell, W. E., Robinson, G. C., and Nanstad, R. K. Impact of radiation embrittlement on integrity of pressure vessel supports for two PWR plants. United States: N. p., 1989. Web. doi:10.2172/6371359.
Cheverton, R. D., Pennell, W. E., Robinson, G. C., & Nanstad, R. K. Impact of radiation embrittlement on integrity of pressure vessel supports for two PWR plants. United States. https://doi.org/10.2172/6371359
Cheverton, R. D., Pennell, W. E., Robinson, G. C., and Nanstad, R. K. 1989. "Impact of radiation embrittlement on integrity of pressure vessel supports for two PWR plants". United States. https://doi.org/10.2172/6371359. https://www.osti.gov/servlets/purl/6371359.
@article{osti_6371359,
title = {Impact of radiation embrittlement on integrity of pressure vessel supports for two PWR plants},
author = {Cheverton, R. D. and Pennell, W. E. and Robinson, G. C. and Nanstad, R. K.},
abstractNote = {Recent data from the HFIR vessel surveillance program indicate a substantial radiation embrittlement rate effect at low irradiation temperatures (/approximately/120/degree/F) for A212-B, A350-LF3, A105-II, and corresponding welds. PWR vessel supports are fabricated of similar materials and are subjected to the same low temperatures and fast neutron fluxes (10/sup 8/ to 10/sup 9/ neutrons/cm/sup 2//center dot/s, E > 1.0 MeV) as those in the HFIR vessel. Thus, the embrittlement rate of these structures may be greater than previously anticipated. A study sponsored by the NRC is under way at ORNL to determine the impact of the rate effect on PWR vessel-support life expectancy. The scope includes the interpretation and application of the HFIR data, a survey of all light-water-reactor vessel support designs, and a structural and fracture-mechanics analysis of the supports for two specific PWR plants of particular interest with regard to a potential for support failure as a result of propagation of flaws. Calculations performed thus far indicate best-estimate critical flaw sizes, corresponding to 32 EFPY, of /approximately/0.2 in. for one plant and /approximately/0.4 in. for the other. These flaw sizes are small enough to be of concern. However, it appears that low-cycle fatigue is not a viable mechanism for creation of flaws of this size, and thus, presumably, such flaws would have to exist at the time of fabrication. 59 refs., 128 figs., 49 tabs.},
doi = {10.2172/6371359},
url = {https://www.osti.gov/biblio/6371359}, journal = {},
number = ,
volume = ,
place = {United States},
year = {Sun Jan 01 00:00:00 EST 1989},
month = {Sun Jan 01 00:00:00 EST 1989}
}