Calculated Neutron Spectra of Fast Pulsed Reactors

Flanders, T. M.; Sparks, M. H.

doi:10.1007/978-94-011-2781-3_66

Cited by 4 publications

(2 citation statements)

References 7 publications

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“…The primary reference spectrum for the facility has been the position 60.96 cm from the core centerline. This location has been documented since 1976 [4], and has been extensively re-evaluated through the years [5,6], both experimentally and by calculation. It serves as the basis for comparison to the exposure environments of other facilities and when used as the reference spectrum in national standards.…”

Section: Introductionmentioning

confidence: 99%

A Re-Evaluation of the Reference Environment at the WSMR Fast Burst Reactor

Sparks¹,

Flanders²

2016

EPJ Web of Conferences

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Abstract. This paper reviews the primary reference field at 60.96 cm from core centreline and re-examines the reference environment with improved characterizations of the reactor structure, test fixtures and also addresses some smaller issues of non-tracking calculations by monte carlo methods with various cross section set generations. We are also addressing long standing issues of absolute normalization of integral fluence based on the original characterizations of the facility diagnostic instrumentation.

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Section: Introductionmentioning

confidence: 99%

A Re-Evaluation of the Reference Environment at the WSMR Fast Burst Reactor

Sparks¹,

Flanders²

2016

EPJ Web of Conferences

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“…The exposure cell has thick concrete walls lined with gypsum and borated gypsum wall board. The free field neutron environment at any position in the cell is a combination of the slightly degraded fission spectrum leaking from the reactor and a wall-return component which ties to the fission spectrum at a few keV in energy [1][2][3].The MoLLY-G core is a cylindrical assembly consisting of six annular fuel rings made of enriched uranium-molybdenum alloy. The safety block is a large fuel element which is inserted into the central cavity of the core.…”

mentioning

confidence: 99%

Highly Perturbed Operational Test Configurations at the WSMR Fast Burst Reactor

Flanders¹,

Sparks²,

Daniel³

2016

EPJ Web of Conferences

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Abstract. The White Sands Missile Range (WSMR) MoLLY-G reactor has a long history of producing a well characterized environment for testing electronic systems/devices in fission environments. As an unmoderated, unreflected, bare critical assembly, it provides a slightly degraded fission spectrum with a 1/E tail. For radiation hardness testing of electronics, the neutron fluence is usually reported as the 1-MeV Equivalent Neutron Fluence for Silicon. In this paper, we examine additional neutron environments and characterizations ranging from low intensity neutron fields to more extreme modifications of our normal test environment. White Sands Missile Range MoLLY-G ReactorThe WSMR MoLLY-G reactor is an unmoderated, unreflected bare critical assembly. The reactor can be operated in either the steady state mode at the several kilowatt level or made super prompt critical, producing a pulse with a full-width half-maximum time of 45 microseconds or longer. The neutron spectrum leaking from the reactor is a slightly degraded fission spectrum. The reactor is operated in an exposure cell approximately 15 m by 15 m by 6.1 m high. The exposure cell has thick concrete walls lined with gypsum and borated gypsum wall board. The free field neutron environment at any position in the cell is a combination of the slightly degraded fission spectrum leaking from the reactor and a wall-return component which ties to the fission spectrum at a few keV in energy [1][2][3].The MoLLY-G core is a cylindrical assembly consisting of six annular fuel rings made of enriched uranium-molybdenum alloy. The safety block is a large fuel element which is inserted into the central cavity of the core. The fuel rings are bolted to a stainless steel support plate by three Inconel metal bolts. There is a stainless steel retaining plate at the top of the core. The power level of the core is adjusted by two control rods of the same fuel alloy which are inserted into voids in the body of the rings. A third control rod can be pneumatically driven into the core for burst operations. The core is covered by a cylindrical decoupling shield containing a 10 B loaded silastic. The decoupling shroud minimizes the effect of reactivity changes due to experiments and other environmental considerations external to the core. The core geometry is shown schematically in Fig. 1 with a typical MCNP [4] model of the core shown in Fig. 2. A more comprehensive model used for spectral characterization at experimental a Corresponding

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Investigation of Radiation Transport Modeling Trends in the WSMR Fast Burst Reactor Environments

Sparks¹,

Sallee²,

Flanders³

et al. 2007

Journal of ASTM International

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Radiation transport calculations provide the backbone for the spectrum characterization used to support experimenters at research reactors. The radiation transport calculations provide a priori neutron spectra used in least squares spectrum adjustment. In addition, calculations are often the sole source of baseline neutron spectra data when an experimental test object substantially perturbs the free-field spectrum. It is crucial that analysts provide high fidelity uncertainty quantification for the spectrum calculations. This is an investigation of systematic trends as the distance to the source is varied in calculated spectra at a fast burst facility. A comparison of ratios is designed to highlight trends in the C/E ratios that may shed light on deficiencies in the transport cross sections or sensitivities to the details of the facility modeling. Initial comparisons of the latest IRDF-2002 [1] dosimetry cross section library to the SNL RML [2] cross section library have been made and are discussed.

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Calculated Neutron Spectra of Fast Pulsed Reactors

Cited by 4 publications

References 7 publications

A Re-Evaluation of the Reference Environment at the WSMR Fast Burst Reactor

A Re-Evaluation of the Reference Environment at the WSMR Fast Burst Reactor

Highly Perturbed Operational Test Configurations at the WSMR Fast Burst Reactor

Investigation of Radiation Transport Modeling Trends in the WSMR Fast Burst Reactor Environments

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