Determination of the Agr-1 Capsule to FPMS Spectrometer Transport Volumes From Leadout Flow Test Data

Abstract

The AGR-1 experiment is a fueled multiple-capsule irradiation experiment being conducted in the Advanced Test Reactor (ATR) in support of the Advanced Gas Reactor (AGR) Fuel Development and Qualification Program. A flow experiment conducted during the AGR-1 irradiation provided data that included the effect of flow rate changes on the decay of a short-lived radionuclide ( 23 Ne). This data has been analyzed to determine the capsule-specific downstream transport volume through which the capsule effluents must pass before arrival at the fission product monitoring system spectrometers. These resultant transport volumes when coupled with capsule outlet flow rates determine the transport times from capsule-to-detector. In this work an analysis protocol is developed and applied in order to determine capsule-specific transport volumes to precisions of better than 7%.

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

“…At the end of each irradiation cycle the FPMS measured activities were corrected to account for decay that occurred during transport from the capsules to the detectors. Transport times were calculated from outlet gas flow rates recorded by the automated experiment data control system of the ATR and the capsule-specific volumes through which samples flow to reach the respective monitoring stations [7].…”

On0Line Fuel Failure Monitor for Fuel Testing and Monitoring of Gas Cooled Very High Temperature Reactor

“…It has a half-life (4.48 hours) that is sufficiently short to allow reaching an equilibrium concentration in the fuel, but is long enough that decay during transport from the irradiation position to the detector is not significant. The transport time is on the order of 2 to 3 minutes [14] which poses a significant challenge for the detection of the shorter lived radionuclides of interest like Kr-90, Kr-91, and Xe-139. Kr-85m also has a distinct 75.4% yield gamma-ray at 151.2 keV that occurs in a section of the gamma ray spectrum that is relatively free of any other full energy peaks.…”

“…For each capsule the flow rate of the He effluent is continuously monitored and recorded at the ATR. The decay time is determined by the volume of tubing that the fission products must pass through to get to the detector divided by the volumetric flow rate of the effluent [14]. After the release activities are calculated, they are combined with the birth activities calculated from ORIGEN as show in Eq.…”

Preliminary results of an on-Line, multi-spectrometer fission product monitoring system to support advanced gas reactor fuel testing and qualification in the advanced test reactor at the Idaho National Laboratory

“…Based on pressure drop measurements made before test train installation, three of the capsules were deemed most likely to produce leakage into the leadout and result in crosstalk if the leadout flow was too low. These capsules 1, 2, and 5 were tested in turn as follows [5].…”

“…In the capsule under test, the dominant detected species was 23Ne (half life 37.24 sec), [1] the neutron activation product of the 22Ne supplied in the capsule inlet flow. To determine the lowest leadout flow that precluded effluent from the tested capsule from entering other capsules, two pieces of data were of primary importance -the presence or absence of 23Ne in the effluent from capsules that had no Ne supplied in their inlet stream (thus the activated Ne had to come from crosstalk with the capsule under test,) and the measured outlet flow from the tested capsule (an outlet flow rate lower than the inlet flow rate indicated losses to the leadout volume rather than inlet flow from the leadout volume) [5]. These leadout flow experiments determined that a minimum leadout flow of 16 sccm of He was required to eliminate capsule crosstalk.…”