Thermal conductivity of neutron-irradiated reactor graphites

✍ Scribed by R.J. Price

• Publisher: Elsevier Science
• Year: 1975
• Tongue: English
• Weight: 402 KB
• Volume: 13
• Category: Article
• ISSN: 0008-6223
• DOI: 10.1016/0008-6223(75)90232-8

✦ Synopsis

The thermal conductivity of neutron-irradiated reactor-grade graphites made from needle coke (H-327), Gilsocoke (H-328), and isotropic petroleum coke (H-451) was measured between 22 and 800°C. Irradiation temperatures were between 600 and 16OO"C, and fast neutron fluences ranged up to lO22 n/cm* (E >0,18 MeV).

Jrradiation reduces the conductivity toward a saturation level which increases with irradiation temperature. For given irradiation conditions, the reduction in conductivity is greater for the needle-coke graphites than for the isotropic graphites. The dependence of conductivity on measurement temperature is reduced by irradiation. The temperature dependence of the irradiation-induced increase in thermal resistivity is in fair agreement with that predicted from lattice dynamics theory for those vacancy loops which are small compared with phonon wave-lengths. The temoerature deuendence is not consistent with calculations which assume a temperature-independent phonon mean free' path for irradiation-induced defects.