More up-and-down operations at SNS; restart expected later this week after target change

SNS Building MarkerThe Spallation Neutron Source, one of Oak Ridge National Laboratory’s top research facilities, is expected to resume operations later this week after a pause to change a target vessel that failed on March 22.

SNS operations chief Kevin Jones provided an update Tuesday on the situation at SNS, which has experienced an elevator ride of good and bad results over the past year. High-end science is sometimes fragile or so it seems.sns1

According to Jones, the SNS systems had been operating well at high power levels until last Tuesday, when the tech-loaded target vessel reported a “leak condition” — meaning that some of the liquid mercury had breached its containment and entered the “sealed interstitial space” where the sensors are located.

There has been a history of the stainless-steel vessels failing prematurely but that wasn’t necessarily the case in this instance. After all, the SNS had operated under pretty extreme conditions in the most recent run, with a beam power of up to 1.4 megawatts — the maximum — and much longer runs at 1.3 megawatts.

Jones said the SNS ran very well at 1.3 megawatts until the leak was detected.

The target-vessel changeout began on March 23, and Jones said that process was moving ahead well.

“If all continues as such we anticipate resuming operation for users this week,” he said Tuesday.

However, because there will only be one spare vessel in reserve, the SNS management team plans to operate the SNS at reduced beam power — 850 kilowatts — for a while before ramping up to higher levels.

Although the most recent target vessels failed before officials would have liked, Jones said it had received a greater exposure to high beam power of any of the predecessors. Because of that, officials are interested in what caused the failure of the steel vessel.

Jones said the unanticipated shutdown of SNS operations will probably affect 45 experiments and 166 users from 46 research institutions.

“We will reschedule those users as soon as possible,” he said.

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About Frank Munger

Senior Writer Frank Munger covers the Dept. of Energy's Oak Ridge facilities and many related topics — nuclear weapons, nuclear waste and other things nuclear, environmental cleanup and science of all sorts. Atomic City Underground is, first and foremost, a news blog, but there's room for analysis, opinion and random thoughts that have no place else to go.