This document presents the facility - recommended characterization of the neutron, prompt gamma - ray, and delayed gamma - ray radiation fields in the Annular Core Research Reactor ( ACRR ) Fueled - Ring External Cavity II (FREC - II) for the free - field environment at the core centerline. The designation for this environment is ACRR - FRECII - FF - cl. The neutron, prompt gamma - ray, and delayed gamma - ray energy spectra, uncertainties, and covariance matrices are presented as well as radial and axial neutron and gamma - ray fluence profiles within the experiment area of the cavity. Recommended constants are given to facilitate the conversion of various dosimetry readings into radiation metrics desired by experimenters. Representative pulse operations are presented with conversion examples.
The Annular Core Research Reactor (ACRR) recently underwent a multi-department effort to characterize the neutron energy leakage spectra in the reactor High Bay for multiple shielding configurations. The ACRR Operations Department identified and obtained a Rotating Neutron Spectrometer (ROSPEC) from Los Alamos National Laboratories (LANL) for obtaining neutron energy spectra. Spectra were obtained in the following facility configurations; Fuel Ringed External Cavity, Version II (FREC-II) decoupled with the standard FREC shield plug installed with the following operational permutations: the 4-inch central cavity (CC) shield plug removed in both a free-field (FF) and 44(3y (Blead-boron (LB-44) bucket neutron modifier configuration, fully shielded CC plug FF condition, neutron radiography collimator aperture settings 250:1, 125:1, and 65:1, FREC-II coupled with both the lightweight (2T1) and standard shield plug configurations. The ROSPEC spectrum results were unfolded, evaluated and weighted using the International Commission on Radiation Protection (ICRP) 103 neutron radiation weighting factors to obtain a ratio amongst the different shielding configurations at the ACRR. Results of the collected spectra confirm that the predominant neutron energy range in the High Bay area is less than or equal to 250 keV.
This document presents the facility-recommended characterization of the neutron, prompt gamma-ray, and delayed gamma-ray radiation fields in the Annular Core Research Reactor (ACRR) for the cadmium-polyethylene (CdPoly) bucket in the central cavity on the 32-inch pedestal at the core centerline. The designation for this environment is ACRR-CdPoly-CC-32-cl. The neutron, prompt gamma-ray, and delayed gamma-ray energy spectra, uncertainties, and covariance matrices are presented as well as radial and axial neutron and gamma-ray fluence profiles within the experiment area of the bucket. Recommended constants are given to facilitate the conversion of various dosimetry readings into radiation metrics desired by experimenters. Representative pulse operations are presented with conversion examples. Acknowledgements The authors wish to thank the Annular Core Research Reactor staff and the Radiation Metrology Laboratory staff for their support of this work. Also thanks to Drew Tonigan for helping field the activation experiments in ACRR, David Samuel for helping to finalize the drawings and get the parts fabricated, and Elliot Pelfrey for preparing the active dosimetry plots.
Since the 1960's, Sandia National Laboratories (SNL) has conducted radiation effects testing for the Department of Energy (DOE) and other contractors supporting the DOE. Over this time, SNL's Technical Area V (TA-V) has operated research reactor facilities whose primary mission is providing appropriate neutron radiation environments for radiation testing and qualification of electronic components and other devices. The current generation of reactors includes the Annular Core Research Reactor (ACRR), a water-moderated pool-type reactor, fueled by elements constructed from UO 2-BeO ceramic fuel pellets, and the Sandia Pulse Reactor (SPR), a bare metal fast burst reactor utilizing a uranium-molybdenum alloy fuel. The ACRR has a 9-inch inner diameter central cavity, providing a means to expose reasonably large experiments to an epithermal neutron radiation environment. The ACRR also has a 20-inch inner diameter excore cavity surrounded by U-ZrH fuel elements to accommodate larger experiments. The SPR has a 6.5-inch inner diameter cavity, providing a means to expose experiments to neutron radiation environment which approximates a fission spectrum. The SPR is operated in a large reactor room which allows for experiments to be located external to the reactor and irradiated by the neutrons which leak from the reactor. Both the ACRR and the SPR may be operated in a steady-state or pulsed mode. In pulse mode, the ACRR and SPR can attain high-power pulses on the order of 40 GW (10 ms pulse width) and ISO GW (80 μs pulse width), respectively. The ACRR can also be operated in a transient mode, allowing for tailored power profiles ranging from tens to a few hundred MW for durations of a few seconds. The reactors have also been utilized to perform reactor fuel materials testing, reactor accident phenomenology testing, investigation of reactorpumped lasers, and space reactor fuel component testing. Various tests have included effects such as melting and vaporization of materials due to fission heating and have been conducted in environments including molten sodium, hydrogen gas, mechanical shocks greater than 1000 g, and cryogenic temperatures. In addition, TA-V has performed a variety of critical assembly experiments for purposes of gathering reactor physics benchmark data for space reactor fuel, and characterization of fission product reactivity effects for transportation criticality studies. This presentation provides an overview of the various radiation effects testing and critical experiment facilities, their capabilities and radiation environments, and the wide variety of testing for which the facilities have been utilized.