Materials Selection for the HFIR Cold Neutron Source

Farrell, K.

Oak Ridge National Laboratory (United States)

关键词: Cold Neutrons;    Aluminium;    Alloys;    Thermal Conductivity;    08 Hydrogen;   

DOI  :  10.2172/786477
RP-ID  :  ORNL/TM-1999/208
RP-ID  :  AC05-00OR22725
RP-ID  :  786477

美国|英语

来源: UNT Digital Library

【 摘 要 】

In year 2002 the High Flux Isotope Reactor (HFIR) will be fitted with a source of cold neutrons to upgrade and expand its existing neutron scattering facilities. The in-reactor components of the new source consist of a moderator vessel containing supercritical hydrogen gas moderator at a temperature of 20K and pressure of 15 bar, and a surrounding vacuum vessel. They will be installed in an enlarged beam tube located at the site of the present horizontal beam tube, HB-4; which terminates within the reactor's beryllium reflector. These components must withstand exceptional service conditions. This report describes the reasons and factors underlying the choice of 6061-T6 aluminum alloy for construction of the in-reactor components. The overwhelming considerations are the need to minimize generation of nuclear heat and to remove that heat through the flowing moderator, and to achieve a minimum service life of about 8 years coincident with the replacement schedule for the beryllium reflector. 6061-T6 aluminum alloy offers the best combination of low nuclear heating, high thermal conductivity, good fabricability, compatibility with hydrogen, superior cryogenic properties, and a well-established history of satisfactory performance in nuclear environments. These features are documented herein. An assessment is given of the expected performance of each component of the cold source.