SNS Target Systems initial operating experience

SNS October 2008 status

“…Commissioning and initial operating experience up to 300 kW have been previously reported [1,2]. For the first run cycle in FY2008 of approximately 2000 h 100% availability was achieved.…”

“…The helium refrigeration system originally had a problem with a loss of capacity with time such that the system had to be warmed up about every 3 weeks [2]. The problem was suspected to be a gravity driven instability in the heat exchanger.…”

Lead–gold eutectic: An alternative liquid target material candidate for high power spallation neutron sources

“…Further patterns were recorded as function of temperature for some of the samples using a TTK450 Anton Paar chamber. The experiments were carried 3 The boiling point of LBE is $1670°C and Lead boils at 1749°C. Because Gold shows with 2856°C, a substantial higher boiling point than Bismuth (1564°C), it is reasonable to assume that the boiling point of LGE is >1700°C.…”

“…To solve this problem, SNS in the USA [3] and JSNS in Japan [4], the only pulsed spallation facilities working with average beam powers close to 1 MW, have opted to use flowing liquid metal targets 1 [5] (a rotating solid target is also being considered for the SNS 2nd target station). This choice has the advantage of enabling the transport of the target material out of the beam interaction area and to refrigerate it elsewhere.…”

A comparison between the chemical behaviour of lead-gold and lead-bismuth eutectics towards 316L stainless steel

“…with bismuth, lead-bismuth eutectic (LBE). Currently two spallation sources operating with mercury exist in the US (SNS, ORNL, [2]) and in Japan (J-PARC, JAERI, [3]). Mercury was also considered as a possible target material for the European Spallation Source (ESS, Sweden, [4]) in the past, but has currently been dropped due to serious disposal issues, since there is no proven technology for solidification and storage of large amounts of radioactive mercury [5].…”