Next major decision anticipated for second target station at SNS

The next decision about the second target station at the Spallation Neutron Source could be made later this year or in the first quarter of next year, U.S. Energy Secretary Dan Brouillette told a House subcommittee on Thursday. The next decision would include an alternative selection and a cost range.

The $1.4 billion SNS is located on Chestnut Ridge at Oak Ridge National Laboratory. It provides neutrons for research.

The second target station has been part of SNS plans for many years. It’s one of two upgrades being pursued at SNS. The other is a proton power upgrade, which is expected to double the power of SNS’s proton beam from 1.4 megawatts to 2.8 megawatts.

The second target station has a current estimated cost range of $800 million to $1.5 billion. The U.S. Department of Energy said the second target was needed more than a decade ago, in January 2009. The second target station would use a narrow proton beam and a compact, rotating, water-cooled tungsten target. It is expected to fill gaps in materials research that require the combined use of intense, cold (longer wavelength) neutrons and instruments that can help analyze complex materials. It could have up to 22 experimental beamlines.

The second target station would produce neutrons in a much smaller volume than those reaching the first SNS target, the mercury target. It would receive 10 proton pulses per second, while the existing target station will receive 50 pulses per second, according to a January 2015 technical report. A 60-hertz pulse stream is currently delivered to the first target station.

In 2017, Oak Ridge Today reported that the second target station project could include about 380,000 square feet of new construction, mostly on a 12-acre site on the east end of the SNS campus, and it would support about 300 permanent staff and visiting users. The Chestnut Ridge campus would then include about 1.1 million square feet of space and roughly 900 people.

Work under way now or expected in the next fiscal year includes planning, research and development, and engineering activities, according to the U.S. Department of Energy’s budget request for fiscal year 2021.

U.S. Representative Chuck Fleischmann, a Tennessee Republican whose district includes Oak Ridge, asked Brouillette about the second target station during a DOE budget hearing with the House Energy and Water Development Subcommittee on Thursday.

“I am very excited about the plans for the construction of the Second Target Station at the Spallation Neutron Source,” said Fleischmann, a subcommittee member.

Specifically, Fleischmann wanted to know when critical decision 1, or CD-1, might be issued. CD-1—the second step in a five-step process that DOE uses to manage projects—includes a cost range and the selection of an alternative.

Brouillette said CD-1 is anticipated toward the end of this year or possibly in the first quarter of next year.

Congress included $37 million in fiscal year 2020, the current fiscal year, for the second target station and $60 million for the proton power upgrade. The Trump administration has proposed reductions, compared to current spending, in the next fiscal year, which starts October 1. Under the president’s budget request, funding for the second target station could drop to $2 million in fiscal year 2021, and spending for the proton power upgrade could fall to $8 million.

But it’s not clear that Congress will approve the requested decreases. In several areas studied by Oak Ridge Today, legislators have been providing more money for DOE activities than what the Trump administration has been requesting. Under the U.S. Constitution, Congress has the authority to appropriate federal funding.

Fleischmann said the second target station is critical to maintaining U.S. leadership in neutron science. Besides doubling the capacity of SNS, it will provide new capabilities and allow researchers to study the structure and dynamics of materials from polymers to proteins to catalysts, Fleischmann said.

The proton power upgrade that would double the power at SNS has a current cost estimate range of between $184 million and $320 million. Work under way on that project or planned in the next fiscal year includes research and development, engineering, preliminary and final design, testing, fabrication, and procurement.

SNS generates neutrons by propelling protons down a linear accelerator. When the protons collide with a liquid mercury target, they create a “spall” of neutrons that are corralled into beam lines linked to surrounding research instruments.

The Spallation Neutron Source started operating in 2006. It provides the most intense pulsed neutron beams in the world for scientific research and industrial development. It’s one of two neutron sources at ORNL. The other is the High Flux Isotope Reactor, or HFIR. The second target station at SNS would be a third neutron source.