SNS target tests at the LANSCE-WNR in 2001 – Part I

Testing of mercury filled targets in an 800 MeV proton beam was conducted at the Los Alamos Neutron Science Center-Weapons Neutron Research (LANSCE-WNR) facility on two occasions in 2001. The objective for the first test campaign was to investigate if target vessel cavitation damage could occur under transient pressure conditions much like the Spallation Neutron Source (SNS) target. Such an investigation was inspired after mechanical tests conducted by a Japan Atomic Energy Research Institute (JAERI/KEK) team revealed cavitation pitting in a mercury container having comparable pressure wave intensity. The first WNR test confirmed cavitation damage with 200 proton pulses on each of two test targets. As a result, concerns arose that the lifetime of the SNS target could be seriously limited. A second test campaign was then prepared and conducted to investigate if alternate target materials or geometries could reduce or eliminate the damage. Tested materials included Stellite, Nitronic-60 as well as 316LN stainless steel (the baseline SNS target material) that was cold worked and surface hardened. Theories that the original test target geometry caused the damage were checked with tests using thick beam windows and a target with a non-axisymmetric shape. This paper describes the test program and covers target preparation, irradiation conditions, post-test decontamination and an overview of the examinations performed. J.D. Hunn covers the detailed description of the metallurgical examinations in another paper here at IWSMT-5.