<p>The primary focus of this thesis pertains to R&D results associated with deploying tensioned</p>
<p>metastable fluid detector (TMFD) technology for monitoring of spent nuclear fuel</p>
<p>(SNF) for actinide content from their neutron emissions while under extreme photon backgrounds</p>
<p>(> 150 Gy/h), as may be expected within a hotcell. Traditional state-of-the-art</p>
<p>neutron detectors such as 3He and BF3 based systems are well-known to be dysfunctional</p>
<p>under such conditions, despite having pulse-shaped discrimination capabilities that allow</p>
<p>them to differentiate photons vs. neutrons. The aim of this thesis was to test the ‘gamma</p>
<p>blind’ ability of the centrifugally tensioned metastable fluid detector (CTMFD) based system,</p>
<p>to monitor for actinide generated neutrons despite the anticipated high intensity gamma</p>
<p>background, a goal which was successfully accomplished. Methods, designs, and experimental</p>
<p>procedures are discussed for successful neutron monitoring from an Americium-Beryllium</p>
<p>neutron source, as well as results showing no hindrance to neutron detection capability at</p>
<p>modest negative pressure states through 150 Gy (15 kRad) accumulated gamma dose.</p>
<p>A secondary focus was the ability of the TMFD based systems to perform alpha spectroscopy</p>
<p>on closely separated (<10 keV) alpha particle emissions from 239Pu and 240Pu</p>
<p>isotopes. Due to the closely spearated alpha decay energies, this feat could previously only</p>
<p>be perfromed by tedious and expensive mass-spectrometry based systems. Instead, a wet</p>
<p>chemistry apporach for detecting trace (? 10−3 Bq/mL) quantity alpha radiation with high</p>
<p>alpha energy resolution (<10 keV) was developed and validated using the CTMFD system.</p>
<p>Using this technique, mixtures containing samples of 239Pu:240Pu with activity concentrations</p>
<p>ranging in ratio from 1:0 to 0:1 were able to be identified within ±12% accuracy.</p>
<p>Lastly, successful assessments were conducted for detecting neutron emissions from a 1</p>
<p>Ci Plutonium-Beryllium source under a variety of shielded configurations using a CTMFD</p>
<p>and a 3He based Ludlum 42-49BTM detector. Concrete, lead, and water shielding materials</p>
<p>of thicknesses ranging from 0 to ?30 cm were placed as shielding material, with the</p>
<p>CTMFD configured only for fast energy neutron detection. Monte Carlo N-Particle Transport</p>
<p>(MCNP) code-based simulations were performed for derivation of the neutron energy</p>
<p>spectrum incident on the detectors to compute sensitivity estimates. At 0.6 MPa (6 bar) negative pressure, the CTMFD was determined to offer up to 7 times higher sensitivity vs the</p>
<p>Ludlum 42-49B, though further increasing the negative pressure state to 1.1 MPA (11 bar)</p>
<p>exponentially increases the sensitivity to offer 100+ times higher sensitivity for the CTMFD</p>
<p>vs the Ludlum 42-49B.</p>
| Identifer | oai:union.ndltd.org:purdue.edu/oai:figshare.com:article/22677397 |
| Date | 24 April 2023 |
| Creators | Catalin A Harabagiu (15339178) |
| Source Sets | Purdue University |
| Detected Language | English |
| Type | Text, Thesis |
| Rights | CC BY 4.0 |
| Relation | https://figshare.com/articles/thesis/ADVANCED_STUDIES_ON_GAMMA_BLINDNESS_HIGH_RESOLUTION_HYBRID_MASS_ALPHA_STPECTROSCOPY_EXTRACTION_AND_NEUTRON_DETECTION_WITH_CTMFDS/22677397 |
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