Abstract
The Second Target Station (STS) at the Spallation Neutron Source (SNS) will address emerging scientific challenges by providing a source of intense cold neutrons to instruments optimized for this source. The STS target will use rotating tungsten blocks and will receive 1.3 GeV proton beam pulses from the SNS accelerator at a repetition rate of 15 Hz. The facility life is planned for 40 years, and each target assembly life is expected to be approximately 10 years. An accurate strain prediction is then critical for fatigue life assessment of STS target blocks because they will be subject to approximately 108 beam pulses per lifetime. As an R&D activity, the Los Alamos Neutron Science Center (LANSCE) Weapons Neutron Research (WNR) Target 2 (Blue Room) facility was used to test the strain response of prototypical target blocks to the thermal shock of a proton pulse. The blue room was well suited for a pulsed proton beam impact test of subscale STS target blocks; the 800 MeV proton energy is approximately 60 % of the 1.3 GeV proton energy expected from the SNS accelerator to the STS. The LANSCE Proton Storage Ring (PSR) and SNS are both short-pulse proton beam sources with nominal pulse widths of 250 ns and 661 ns, respectively, so the energy deposition in the target occurs in <1 μs pulse duration. Strain measurements on the outer surface of three target blocks (bare tungsten, tantalum-clad tungsten, niobium-clad tungsten) were recorded for comparison against neutronics and structural simulations. This experiment and the supporting simulations satisfied the following primary research goals for the STS target.
| Original language | English |
|---|---|
| Article number | 171086 |
| Journal | Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment |
| Volume | 1083 |
| DOIs | |
| State | Published - Mar 2026 |
Funding
The experiment and the supporting simulations satisfied the following primary research goals for the STS target as follows.The authors thank Hao Jiang for providing sensor debonding test experience at SNS and Erica Heinrich for technical editing. The authors also wish to thank the many colleagues at ORNL who contributed to the success of this experiment: Ken Gawne—fixture design; Aaron Jacques—apparatus design and testing; Adam Kubik, Doug Kyle, Thomas Muth, Jessica Osborne—test article manufacturing and inspection; Yongjoong Lee—experiment design; Cary Long, Sydney Murray III, Robert Sangrey, Richard Schwartz, Alexander Zhukov—experiment support and testing; Thomas McManamy—analysis-scoping studies; Scott Schwahn, Kimberly Isbell—radiological measurements and testing. This research used resources of the SNS STS Project at ORNL. ORNL is managed by UT-Battelle LLC for DOE's Office of Science, the single largest supporter of basic research in the physical sciences in the United States. This work was performed, in part, at the Los Alamos Neutron Science Center (LANSCE), a National Nuclear Security Administration user facility operated for DOE by Los Alamos National Laboratory (Contract 89233218CNA000001). This research used resources of the SNS STS Project at ORNL. ORNL is managed by UT-Battelle LLC for DOE's Office of Science, the single largest supporter of basic research in the physical sciences in the United States. This work was performed, in part, at the Los Alamos Neutron Science Center (LANSCE), a National Nuclear Security Administration user facility operated for DOE by Los Alamos National Laboratory (Contract 89233218CNA000001). This manuscript has been authored by UT-Battelle, LLC, under contract DE-AC05-00OR22725 with the US Department of Energy (DOE). The US government retains and the publisher, by accepting the work for publication, acknowledges that the US government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce the submitted manuscript version of this work, or allow others to do so, for US government purposes. DOE will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan ( https://energy.gov/doe-public-access-plan ).
Keywords
- Dynamic strain response
- Fiber optic strain sensor
- Spallation neutron source
- Spallation target
- Tantalum-clad tungsten
- Thermal shock
- Thermomechanical fatigue