Fast-Neutron Hodoscope at Treat: Development and Operation

Volpi, A. De; Pecina, R.; Daly, R. T.; Travis, D.; Stewart, R.R.; Rhodes, E. A.

doi:10.13182/nt75-1

Cited by 34 publications

(8 citation statements)

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“…The TREAT facility includes a relatively simple neutron radiography station with an L/D of 30, which is used as part of the experiment operations to evaluate the condition of experiments before and after transients. TREAT also includes a fast neutron hodoscope, which tracks fuel movements during transients through time-resolved in-situ fast neutron radiography (DeVolpi, 1975). The hodoscope and radiography stations at TREAT are currently undergoing maintenance and refurbishment upgrades to return them to operation as part of the TREAT restart program.…”

Section: Upgrading and Developing New Neutron Imaging Capabilitiesmentioning

confidence: 99%

Neutron Radiography of Irradiated Nuclear Fuel at Idaho National Laboratory

et al. 2015

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Neutron radiography of irradiated nuclear fuel provides more comprehensive information about the internal condition of irradiated nuclear fuel than any other non-destructive technique to date. Idaho National Laboratory (INL) has multiple nuclear fuels research and development programs that routinely evaluate irradiated fuels using neutron radiography. The Neutron Radiography reactor (NRAD) sits beneath a shielded hot cell facility where neutron radiography and other evaluation techniques are performed on these highly radioactive objects. The NRAD currently uses the foil-film transfer technique for imaging fuel that is time consuming but provides high spatial resolution. This paper describes the NRAD and hot cell facilities, the current neutron radiography capabilities available at INL, planned upgrades to the neutron imaging systems, and new facilities being brought online at INL related to neutron imaging.

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Section: Upgrading and Developing New Neutron Imaging Capabilitiesmentioning

confidence: 99%

Neutron Radiography of Irradiated Nuclear Fuel at Idaho National Laboratory

et al. 2015

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“…5-8), and EOC-4 (pp. [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21] identify this pin as being equivalent to the first pin to fail (channel 3) in BOC-4 of FTR. The retained fission-gas distribution in HEDL-NF-056 was estimated (see Fig.…”

Section: )mentioning

confidence: 99%

Failure of a high-power pin in a simulated $3/s TOP accident: Test E6 final report

Doerner¹,

Ståhl²,

Murphy³

et al. 1978

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14.16dle . expas r". Failure occurred 70 ms earlier than predicted inthe PSAR. 3.Postfailure fuel motion was principally upward in direction and from the center of the cluster, with no more than 10 g of total fuel loss.4. The outlet blockage was formed in stages. 5.The irradiated fuel is more mobile than fresh fuel. 6.There were no significant fuel-coolant interactions. The lower one-third of the test pin suffered only minor cladding damage and no inlet blockage was formed.It is concluded that the mechanisms that led to initial failure can be reliably applied to the FTR. Characterization of the initial fuel release in amount, location, structure (soid. liquid or foam), and rate were reasonably prototypic. Postfailure coolant dynamics. however, were not very prototypic. Although the amount of fuel swept out is probably realistic, the formation of an outlet blockage and its impact on adjacent channel hydraulics is clearly nonprototypic. 8 mm), and was previously irradiated in EBR-II to a burnup of ~4 at. %, but at a more prototypic fast fluence (4 x 1022 nvt).The major purpose of Test E6 was to identify the sequence of failure events associated with high-power fuel in a hypothetical $3/s transientoverpower (TOP) accident in the FTR. Of particular interest are the timing of events, the magnitude of any fuel or cladding thermal interactions with the coolant, the rate and total amount of fuel that is redistributed, and the propensity for cladding and fuel relocations, including the formation of blockages.A secondary objective of Test E6 was to contribute to the body of data used in verifying failure models built into the large accident-analysis codes. To this end, failure thresholds and coolant-dynamics models in such codes as SAS3A and MELT-III have been partially verified by TREAT experiments. B. Relation to FTRTwo types of accidents are identified in the FTR safety analyses: a loss of sodium-coolant flow due to a pump failure or a pipe rupture (LOF), and a TOP excursion due to the accidental insertion of reactivity. Both have been extensively analyzed by the detailed accident-analysis codes SAS 3 and MELT-III.' 4 Since many of the phenomenological models built into these codes have not been, and indeed, may never be, tested, the loop experiments provide important support to the sequence and magnitudes of postulated events.In the analysis of the TOP accident, it was postulated's that the maximum reactivity available in all the control rods was added at the maximum rate possible. It was further assumed that the plant-protection system (PPS) failed to shut the reactor down. An uncontrolled rod withdrawal in FTR produces a reactivity ramp of 6 /s to a total insertion of as much as $5 reactivity. A ramp rate of about an order of magnitude higher than this (50 /s) was chosen as the base case in the PSAR. A $3/s ramp, corresponding to the design limit of the FFTF PPS, was studied parametrically for rate-dependent effects. A power history corresponding to the $3/s PPS limit was used in Test E6.Predictions of failure ti...

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“…TREAT is an air-cooled graphite-moderated thermal reactor fueled by a zircaloy-clad mixture of enriched UO 2 and graphite. A test section in the core allows for a direct line of sight to fuel elements under test from outside the reactor [1]. To monitor and characterize the test element, a means of recording images is required.…”

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confidence: 99%

“…To monitor and characterize the test element, a means of recording images is required. TREAT was developed when considerable interest was devoted to liquid-metal fast breeder reactors, and the eventual use of opaque fuel capsules and sodium coolant precluded an optical system from being used [1]. Consequently, an alternative imaging mechanism was designed in the form of the Hodoscope.…”

mentioning

confidence: 99%

“…Fast neutrons that are produced in a test fuel device, which escape the core and stream through the front-collimator slit 2020 JINST 15 P09025 and rear-collimator channels, are the primary radiation measured in the FMMS. Gamma rays have also been considered as an imaging modality, but their use was shown to have a poor signal to noise ratios to use, with signal being up to 2.5 times smaller than the background in certain conditions [1].…”

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confidence: 99%

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Optimization and characterization of a silicon photomultiplier-based ZnS(Ag) proton recoil fast neutron detector for nuclear fuel performance monitoring at TREAT

et al. 2020

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The restart of the Transient Reactor Test Facility (TREAT) at Idaho National Laboratory and consequent refurbishment of the Fuel Motion Monitoring System (FMMS), or Hodoscope, offers the opportunity to upgrade the detector system used for neutron imaging. Silicon photomultipliers (SiPMs) are a viable option for updating the Hodoscope to yield improved fuel monitoring capability. The Hodoscope uses ZnS(Ag) proton recoil scintillators (PRS) that provide good gamma-ray suppression and discrimination. Previous work showed that the Hamamatsu S13360-6075CS SiPM offers the best neutron detection and gamma-ray discrimination capability with the ZnS PRS. This work optimizes a SiPM-based detector and develops a PRS prototype for testing. Specifically, possible overvoltages for use are determined by confirming steady operation over extended measurement times. In addition, various SiPM-circuit implementations are tested to optimize the detector according to desired properties, and ultimately a PRS prototype is developed with modifiable components for versatile testing. Measurements of the neutron detection efficiency and gamma-ray rejection efficiency of SiPM-based PRS detectors and a reference PMT-based detector are also carried out. Neutron detection efficiency ranges between 1–2%, and detected gamma-ray rejection efficiency is on the order of 10−7. Use of a low-pass filter only or a low-pass filter and 50-ω shunt resistor is recommended for the SiPM-based detector, and both configurations demonstrate improved performance over the PMT-based detector.

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Fast-Neutron Hodoscope at Treat: Development and Operation

Cited by 34 publications

References 0 publications

Neutron Radiography of Irradiated Nuclear Fuel at Idaho National Laboratory

Neutron Radiography of Irradiated Nuclear Fuel at Idaho National Laboratory

Failure of a high-power pin in a simulated $3/s TOP accident: Test E6 final report

Optimization and characterization of a silicon photomultiplier-based ZnS(Ag) proton recoil fast neutron detector for nuclear fuel performance monitoring at TREAT

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