Void formation and helium effects in 9Cr-1MoVNb and 12Cr-1MoVW steels irradiated in HFIR and FFTF at 400/degree/C
Martensitic/ferritic 9Cr-1MoVNb and 12Cr-1MoVW steels doped with up to 2 wt% Ni have up to 450 appm He after HFIR irradiation to /approximately/38 dpa, but only 5 appm He after 47 dpa in FFTF. No fine He bubbles and few or no larger voids were observable in any of these steels after FFTF irradiation at 407/degree/C. By contrast, many voids were found in the undoped steels (30-90 appm He) irradiated in HFIR at 400/degree/C, while voids plus many more fine He bubbles were found in the Ni-doped steels (400-450 appm He). Irradiation in both reactors at /approximately/400/degree/C produced significant changes in the as-tempered lath/subgrain boundary, dislocation, and precipitation structures that were sensitive to alloy composition, including doping with Ni. However, for each specific alloy the irradiation-produced changes were exactly the same comparing samples irradiated in FFTF and HFIR, particularly the Ni-doped steels. Therefore, the increased void formation appears solely due to the increased helium generation found in HFIR. While the levels of void swelling are relatively low after 37-39 dpa in HFIR (0.1-0.4%), details of the microstructural evolution suggest that void nucleation is still progressing, and swelling could increase with dose. The effect of helium on void swelling remains a valid concern for fusion application that requires higher dose experiments. 15 refs., 14 figs., 8 tabs.
- Research Organization:
- Oak Ridge National Lab., TN (USA)
- DOE Contract Number:
- AC05-84OR21400
- OSTI ID:
- 6567246
- Report Number(s):
- CONF-880613-26; ON: DE89004798
- Country of Publication:
- United States
- Language:
- English
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ALLOYS
CARBON ADDITIONS
DAMAGING NEUTRON FLUENCE
DOPED MATERIALS
EMBRITTLEMENT
ENRICHED URANIUM REACTORS
EPITHERMAL REACTORS
FAST REACTORS
FERRITIC STEELS
FFTF REACTOR
FIRST WALL
HELIUM EMBRITTLEMENT
HFR REACTOR
IRON ALLOYS
IRON BASE ALLOYS
IRRADIATION REACTORS
LIQUID METAL COOLED REACTORS
MARTENSITE
MATERIALS
MATERIALS TESTING REACTORS
NEUTRON FLUENCE
PHYSICAL RADIATION EFFECTS
RADIATION EFFECTS
REACTORS
RESEARCH AND TEST REACTORS
RESEARCH REACTORS
SODIUM COOLED REACTORS
STEELS
SWELLING
TANK TYPE REACTORS
TEST REACTORS
THERMAL REACTORS
THERMONUCLEAR REACTOR MATERIALS
THERMONUCLEAR REACTOR WALLS
VOIDS
WATER COOLED REACTORS
WATER MODERATED REACTORS