MCNP/MCNPX model of the annular core research reactor.

DePriest, Kendall Russell; Cooper, Philip J.; Parma, Edward J.

doi:10.2172/895071

Cited by 14 publications

(11 citation statements)

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“…The value of Q for an event is obtained by integrating the signal current (I n (t)), but the value of n requires additional passive dosimetry. Initially, the average neutron fluence was estimated using a detailed ACRR model in MCNP [2], based off of SAND report values for the LB36 environment [3,4]. The estimate of the neutron fluence was refined and/or corrected through the use of appropriate dosimetry monitor foils as shown in Fig.…”

Section: Evaluation Of Calibration Technique In Acrr Lb36 Environmentmentioning

confidence: 99%

Modeling, Calibration, and Verification of a Fission Chamber for ACRR Experimenters

Coburn

Luker

Parma

et al. 2016

EPJ Web of Conferences

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Abstract.When performing research at a reactor facility, experimenters often need to determine the neutron fluence achieved during an operation. Facilities typically provide guidance in the form of neutron fluence per megajoule (MJ) or through passive dosimetry results. After experiment completion, there is sometimes a delay of several days (or weeks) before the passive dosimetry results are available. In the interim, an experimenter does not have confirmation that the desired irradiation levels were reached. Active dosimetry may provide an estimate of neutron fluxes, but few active detectors are available that have been calibrated to measure neutron fluxes obtained inside the Annular Core Research Reactor (ACRR) central cavity environment. For past experiments at the ACRR, the neutron fluence was calculated by integrating the response of a fission chamber rate detection signal and then normalizing this integral to fluence determined from passive dosimetry. An alternative method of directly measuring neutron flux is desired; the new methodology described provides a complete neutron flux profile after a reactor pulse, utilizing fission chamber physics in combination with a compensating ion chamber to extract and convert a current signal to neutron flux as a function of time.

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Section: Evaluation Of Calibration Technique In Acrr Lb36 Environmentmentioning

confidence: 99%

Modeling, Calibration, and Verification of a Fission Chamber for ACRR Experimenters

Coburn

Luker

Parma

et al. 2016

EPJ Web of Conferences

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“…Figures 2 and 3 show the MCNP model of the ACRR [2] with the LB44 bucket and the PLG bucket, respectively, on the 32-inch (81.3 cm) pedestal in the central cavity. The FREC-II model was not included because it is neutronically decoupled (tilted back) from the ACRR for these operations.…”

Section: Neutronics Modelingmentioning

confidence: 99%

Neutron Environment Characterization of the Central Cavity in the Annular Core Research Reactor *

Parma

Naranjo

Lippert

et al. 2016

EPJ Web of Conferences

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Abstract. Characterization of the neutron environment in the central cavity of the Sandia National Laboratories' Annular Core Research Reactor (ACRR) is important in order to provide experimenters with the most accurate spectral information and maintain a high degree of fidelity in performing reactor experiments. Characterization includes both modeling and experimental efforts. Building accurate neutronic models of the ACRR and the central cavity "bucket" environments that can be used by experimenters is important in planning and designing experiments, as well as assessing the experimental results and quantifying uncertainties. Neutron fluence characterizations of two bucket environments, LB44 and PLG, are presented. These two environments are used frequently and represent two extremes in the neutron spectrum. The LB44 bucket is designed to remove the thermal component of the neutron spectrum and significantly attenuate the gamma-ray fluence. The PLG bucket is designed to enhance the thermal component of the neutron spectrum and attenuate the gamma-ray fluence. The neutron characterization for each bucket was performed by irradiating 20 different activation foil types, some of which were cadmium covered, resulting in 37 different reactions at the peak axial flux location in each bucket. The dosimetry results were used in the LSL-M2 spectrum adjustment code with a 640-energy group MCNP-generated trial spectrum, self-shielding correction factors, the SNLRML or IRDFF dosimetry cross-section library, trial spectrum uncertainty, and trial covariance matrix, to generate a least-squares adjusted neutron spectrum, spectrum uncertainty, and covariance matrix. Both environment character-izations are well documented and the environments are available for use by experimenters.

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“…[22][23][24]. Modifications to the ACRR have also been made for the previous medical isotope program and for other programs (Ref.…”

Section: Reactor Design Basismentioning

confidence: 99%

Sandia National Laboratories Medical Isotope Reactor concept.

Coats¹,

Dahl²,

Parma³

2010

Self Cite

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This report describes the Sandia National Laboratories Medical Isotope Reactor and hot cell facility concepts. The reactor proposed is designed to be capable of producing 100% of the U.S. demand for the medical isotope 99 Mo. The concept is novel in that the fuel for the reactor and the targets for the 99 Mo production are the same. There is no driver core required. The fuel pins that are in the reactor core are processed on a 7 to 21 day irradiation cycle. The fuel is low enriched uranium oxide enriched to less than 20% 235 U. The fuel pins are approximately 1 cm in diameter and 30 to 40 cm in height, clad with Zircaloy (zirconium alloy). Approximately 90 to 150 fuel pins are arranged in the core in a water pool ~30 ft deep. The reactor power level is 1 to 2 MW. The reactor concept is a simple design that is passively safe and maintains negative reactivity coefficients. The total radionuclide inventory in the reactor core is minimized since the fuel/target pins are removed and processed after 7 to 21 days. The fuel fabrication, reactor design and operation, and 99 Mo production processing use well-developed technologies that minimize the technological and licensing risks. There are no impediments that prevent this type of reactor, along with its collocated hot cell facility, from being designed, fabricated, and licensed today.4

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MCNP/MCNPX model of the annular core research reactor.

Cited by 14 publications

References 1 publication

Modeling, Calibration, and Verification of a Fission Chamber for ACRR Experimenters

Modeling, Calibration, and Verification of a Fission Chamber for ACRR Experimenters

Neutron Environment Characterization of the Central Cavity in the Annular Core Research Reactor *

Sandia National Laboratories Medical Isotope Reactor concept.

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