The effect of birthrate granularity on the release-to-birth ratio for the AGR-1 in-core experiment

Scates, Dawn M.; Walter, John B.; Maki, John T.; Sterbentz, James W.; Parry, James R.

doi:10.1016/j.nucengdes.2013.11.037

Cited by 3 publications

(3 citation statements)

References 6 publications

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“…In the isotope-specific activation library, the absorption cross sections were set to zero to turn off transmutation for the isotope. With decay and transmutation turned off for the specific isotope, the change in inventory for the isotope divided by the irradiation time results in the birthrate [2].…”

Section: Birthrate Computationmentioning

confidence: 99%

“…The estimated uncertainty in R c can be determined from standard error propagation techniques to be (2) or in terms of relative errors To speed up the calculation of these ratios and to ensure accuracy, a semiautomatic processing code called FP_PostProc was developed. This program accesses the summary file of each spectral analysis to extract the required results for activity at the detector at a given time.…”

Section: Release Activity Computationmentioning

confidence: 99%

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Release-to-Birth Ratios for AGR-2 Operating Cycles 147A through 154B

Scates

2014

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The AGR-2 experiment was a fueled, multiple-capsule irradiation experiment that was irradiated from June 2010 until October 2013 in ATR in support of the Very High Temperature Reactor Technology Development Office's Fuel Development and Qualification Program. An important measure of the fuel performance of these tests is the quantification of the fission product releases over the duration of the experiment. To provide these data for the inert fission gasses, a fission product monitoring system (FPMS) was developed and implemented to monitor the individual capsule effluents for the radioactive species.The FPMS continuously measures the sweep gas from each of the 6 AGR-2 capsules to provide an indicator of fuel irradiation performance. Spectrometer detector systems measure the concentrations of various krypton and xenon isotopes in the sweep gas from each capsule. Eight-hour counting intervals are used to measure the concentrations of . These concentrations, along with gas flow data, are converted to release rates. R/B values provide indicators of initial fuel quality and fuel performance during irradiation.

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Section: Birthrate Computationmentioning

confidence: 99%

Section: Release Activity Computationmentioning

confidence: 99%

Release-to-Birth Ratios for AGR-2 Operating Cycles 147A through 154B

Scates

2014

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“…The usual measurement protocol acquires gamma-ray spectra with counting times of eight hours. This gives adequate measurement sensitivity and provides three sets of results each day which are used to compute daily capsule release activity values [3,4,5]. Transport times from each capsule to its respective FPM are estimated using capsule-specific effluent flow rates and transport volumes, the volumes through which the effluent flows between the capsule and the FPM.…”

Section: Equipment and Measurementsmentioning

confidence: 99%

Quantity of <sup>135</sup>I released from the AGR-1, AGR-2, and AGR-3/4 experiments and discovery of <sup>131</sup>I at the FPMS traps during the AGR-3/4 experiment

Scates¹

2014

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A series of three Advanced Gas Reactor (AGR) experiments have been conducted in the Advanced Test Reactor (ATR) at Idaho National Laboratory (INL). From 2006 through 2014, these experiments supported the development and qualification of the new U.S. tristructural isotropic (TRISO) particle fuel for Very High Temperature Reactors (VHTR). Each AGR experiment consisted of multiple fueled capsules, each plumbed for independent temperature control using a mix of helium and neon gases. The gas leaving a capsule was routed to individual Fission Product Monitor (FPM) detectors. For intact fuel particles, the TRISO particle coatings provide a substantial barrier to fission product release. However, particles with failed coatings, whether because of a minute percentage of initially defective particles, those which fail during irradiation, or those designed-to-fail (DTF) particles, can release fission products to the flowing gas stream. Because reactive fission product elements like iodine and cesium quickly deposit on cooler capsule components and piping structures as the effluent gas leaves the reactor core, only the noble fission gas isotopes of Kr and Xe tend to reach FPM detectors. The FPM system utilizes High Purity Germanium (HPGe) detectors coupled with a thallium activated sodium iodide NaI(Tl) scintillator. The HPGe detector provides individual isotopic information, while the NaI(Tl) scintillator is used as a gross count rate meter. During irradiation, the 135m Xe concentration reaching the FPM detectors is from both direct fission and by decay of the accumulated 135 I. About 2.5 hours after irradiation (ten 15.3 minute 135m Xe half-lives) the directly produced 135m Xe has decayed and only the longer lived 135 I remains as a source. Decay systematics dictate that 135m Xe will be in secular equilibrium with its 135 I parent, such that its production rate very nearly equals the decay rate of the parent, and its concentration in the flowing gas stream will appear to decay with the parent half-life. This equilibrium condition enables the determination of the amount of 135 I released from the fuel particles by measurement of the 135m Xe at the FPM following reactor shutdown. In this paper, the 135 I released will be reported and compared to similar releases for noble gases as well as the unexpected finding of 131 I deposition from intentional impure gas injection into capsule 11 of experiment AGR-3/4. viii ix ACKNOWLEDGMENT

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