DOE OSTI2019
The goal of this project was to design, develop and validate a novel, spectroscopy enabled H*(10) neutron dosimetry system based on the tensioned metastable fluid detector (TMFD) sensor technology. The project team consisted of staff from Oak Ridge National Laboratory (ORNL), Purdue University (PU) and Sagamore Adams Laboratories, LLC (SAL). PU-SAL staff were tasked with the design, development, construction and testing of the H*TMFD hardware and software, along with developing the control and data acquisition software for comparison of predictions from H*TMFD against a commonly accepted and widely used industry standard system; for this project, the Li-I detector coupled to bonner spheres (LiI-BSS) system manufactured by Ludlum, Inc. was utilized as the reference (“gold”) standard – similar in terms of neutron spectroscopy enablement to another industry recognized, albeit, significantly higher cost (est. $300K) system referred to as “ROSPEC” (from BTI, Inc., which was not available for this project). ORNL staff were tasked with providing field-relevant guidance, apparatus and facilities for acquiring data against calibrated neutron sources, and comparing results of H*TMFD against LiI-BSS system predictions in a series of blind-tests conducted at ORNL. Over the course of 12 months, the PU-SAL-ORNL staff successfully accomplished the proposed technical and administrative tasks, inclusive of engaging in outreach to potential users of this technology in the DOE-wide infrastructure. The proposed tasks were successfully accomplished in timely manner; the follow-up type tasks pertaining to SBIR type Phases 2-3 were discussed and are initiated, inclusive of filing for intellectual property (IP) disclosures and possible patent filings by PU’s Office of Technology Commercialization (OTC). Two H*TMFD system architectures (see Exhibits 1 & 2 in the report) were developed and constructed for hand-portability by health-physicists (HPs) – the HP-H*TMFD, and the H*TMFD system which consists of a side-by-side mounted array of 4 TMFDs of 3 different sizes in sensitive volume (including one with borated fluid) that now simultaneously enables neutron energy spectroscopy: single bin for < 0.1 MeV, and 152 energy bins in the 0.1-15.2 MeV range; H*(10) dosimetry from ~5 μRem/h towards 10 R/h ranges. Several experiments were conducted using neutron sources in various configurations (shielded and unshielded). In direct comparison against the LiI-BSS industry standard (acquiring data for 26h each source), the H*TMFD system (acquiring data for ~6h for each source) offered H*(10) dose predictions for the most part accurate to within +/-10% for dose rates in the 100-300 μRem/h range. The LiI-BSS was impractical to use under ultra-low (~10 μRem/h) dose rate space, as also another metering device used at ORNL (Ludlum 4241L non-spectroscopy enabled) for which the lower limit is set by the manufacturer at 100 μRem/h. The enablement for efficient use in timely manner at the 10 μRem/h levels is deemed to be a strong enabling factor for H*TMFD for use in the DOE-nuclear laboratory arena. In terms of weight, the HP-H*TMFD weighs under ~5-7 lb.; the H*TMFD system weighs ~35-lb. As such, it is ~1/4 the weight of an LiI-BSS system weighing ~120 lb (LiI detector with 6 bonner spheres) and, ~1/2 the weight of ROSPEC. As a result of this activity, two involved post-doctoral student staff have now transitioned their knowledge and experiences to DOE’s Pacific Northwest National Laboratory (PNNL). A PU graduate student has also benefited from this project work which formed a principal basis for his Ph.D. dissertation work (in progress).
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗