Published: Jan 1969
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Neutron irradiation can cause the creep rate of a material to increase, decrease, or to remain unchanged. Each of these possible results has been observed in creep during neutron irradiation. In hep alloys increased creep rates have been observed both in Zircaloy-2 and Zr-2.5Nb at creep rates below 10-10 sec-1 at 300 C. At temperatures above 350 C in-reactor creep rates of Zr-2.5Nb are no different from those of unirradiated control tests, whereas in Zircaloy-2 the creep rate may increase, decrease, or remain the same on reactor shutdown, depending on the stress and temperature. Stress relaxation tests reported for zirconium alloys below 100 C resulted in more relaxation during neutron irradiation, suggesting faster creep rates.
In-reactor creep tests for fcc alloys Type 304 stainless steel and Hastelloy X-280 at temperatures above 500 C have resulted in little if any difference in creep rate, although the range of second-stage creep was significantly reduced. Faster in-reactor creep rates are inferred for nickel, copper, and 18-8 stainless steel through greater stress relaxation during neutron irradiation below 100 C.
creep, stress-rupture, irradiation, structural materials, creep rate, stainless steel, Hastelloy-X, Hastelloy-N, zirconium, zirconium alloys
Gilbert, E. R.
Senior research scientist, Pacific Northwest Laboratories, Battelle Memorial Institute, Richland, Washington
Harding, N. E.
Engineer, Pacific Northwest Laboratories, Battelle Memorial Institute, Richland, Washington