Neutron Sciences Directorate

2025, March – The STS Project completed a DOE Office of Science Independent Project Review to assess readiness to proceed to CD-3A approval to prepare the STS construction site. The review committee recommended proceeding to the next steps in the approval process following completion of recommendations.

2024, July – Proton Power Upgrade (PPU) project beam commissioning completed and neutron production resumed. Commissioning demonstrated 1.7 MW of beam power on target at 1.3 GeV. This is a first step in demonstrating that the upgraded accelerator will be capable of meeting the needs of the Second Target Station (STS) project upon its completion.

2024, May – The Basic Energy Sciences Advisory Committee (BESAC) reported on their assessment of future user facility construction projects proposed by the Office of Basic Energy Sciences, to include the STS Project. They concluded that the facility has “the potential to be absolutely central to future world leading science”, but recommended that “the science case must be more fully developed to specify the currently inaccessible grand challenges that the new capabilities can address”.

2024, May – PPU “stub” construction was completed, enabling future construction crews to connect the STS to the beamline without significantly impacting First Target Station operations.

2024, February – After a competitive bidding process, the master agreement for construction manager/general contractor (CM/GC) services for the STS conventional facilities (CF) was awarded to Hensel Phelps (HP), headquartered in Greeley, Colorado.

2023, August – Construction began on adding a 3,000-square-foot concrete tunnel, called the “stub,” to the existing Spallation Neutron Source (SNS) tunnel. The stub, part of the PPU project at the SNS, will eventually allow the upgraded accelerator to be connected to the planned STS at SNS with minimal disruption.

2022, May – Chaired by Los Alamos National Laboratory Director Thom Mason, STS project managers met with a Project Advisory Board of world-recognized experts to obtain constructive advice designed to assist the project in successfully meeting goals.

2021, July – The STS instrument selection process was completed and the eight world-class instruments to be built during the construction phase were identified. Additionally, after a competitive bidding process, the Architecture Engineering (AE) Design contract for facilities and infrastructure for the STS was awarded to Burns & McDonnell, based in Kansas City, Missouri.

2020, November – DOE approved the project’s Critical Decision-1 (CD-1) status. The significance of CD-1 is it affirmed ORNL’s approach for the project’s conceptual designs, cost and schedule range, and general acquisition plans, while allowing the team to start on preliminary designs.

2020, January – The STS at SNS First Experiments report was issued.

2019, December – ORNL hosted the Science at the Second Target Station (STS) Workshop.

2019, October – Dedicated STS Project Office established.

2017, April – Expert’s panel reviewed and confirmed the selection of major STS technical alternatives: 15 Hz pulse repetition rate, 700 kW proton beam power, short pulse options.

2016, June – A DOE advisory committee recommended ORNL convene an expert’s panel to evaluate STS design parameters and to work with the research community to develop a compelling set of first experiments.

2016, January – Initiated STS conceptual design activities.

2015, October – Workshop organized by the SNS and High Flux Isotope Reactor (HFIR) User Group, bringing the science community together to further develop the STS science case.

2013, 2014 – Grand Challenge workshops were held across the US, collecting the science community’s input on emerging science needs that require research using neutrons. Input helped shape the science case. A technical design report describing the subsystem preconceptual design approaches was written.

2013 – A DOE advisory committee noted that the proposed STS at SNS is “absolutely central” to US leadership in science but had significant scientific/engineering challenges to resolve.

2011, 2012 – ORNL conducted a study on optimizing neutron scattering at three ORNL facilities and developed the concept for a compact source coupled to a high-brightness moderator for STS.

2009 – DOE approved CD-0, acknowledging the scientific need for a Second Target Station (STS) at SNS.

2007 – ORNL conducted a study to investigate the possibility of a Second Target Station (STS) for SNS. DOE issued the Interim Report on Facilities for the Future of Science, identifying the need for an SNS power upgrade and the STS.

2002 – The National Science Foundation commissioned a study of a Second Target Station (STS) for SNS.

1999 - Environmental Impact Statement for SNS included a Second Target Station (STS).

1996 – A DOE advisory committee recommended that SNS be designed to eventually operate at a significantly higher power and include additional target stations.