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At least 685 records · Page 38
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Sensitivity Calculations for Systems with Polyethylene Reflector Materials Using CLUTCH

The SCALE 6.2.4 code package contains four sequences for calculating $k_{eff}$ sensitivity coefficients. Two of these sequences use deterministic transport solvers: a one-dimensional (1D) capability based on XSDRN, and a two-dimensional (2D) capability based on NEWT. These sequences are restricted to the multigroup (MG) treatment of neutron energy. The three-dimensional (3D) sequences use the KENO V.a or KENO-VI Monte Carlo transport codes and can be used to calculate sensitivity coefficients with either MG or continuous-energy (CE) transport. The 3D sensitivities are ultimately reported in an MG structure, regardless of the method used in the transport calculations. If desired, the sensitivity coefficients can be reported with very fine energy resolution from a CE calculation, but they are calculated only in the MG library structure in the MG mode. CE TSUNAMI methods are available in SCALE starting in SCALE version 6.2. Sensitivity coefficients were generated using the 3D sequences as part of the generation of the SCALE 6.2.2 Validation Report; difficulties encountered when using the CLUTCH method for thick, fissionable-material reflectors were discussed and investigated as documented in a previous paper. This paper discusses the difficulties encountered in generating accurate sensitivity coefficients using the CLUTCH technique for polyethylene reflectors for two fast spectrum benchmarks. Direct perturbation (DP) calculations were performed to confirm the accuracy of the total sensitivity coefficient for important isotopes with large sensitivities in the system. Discrepancies were detected for CLUTCH-calculated sensitivity coefficients in the reflector of a critical experiment with a radial polyethylene reflector. A simple polyethylene-reflected plutonium sphere was then used to further investigate the discrepancy. Calculations performed using the iterated fission probability (IFP) method generated accurate sensitivity coefficients in both cases. The results of this study emphasize the need to confirm CLUTCH sensitivity results with DP calculations. IFP calculations are generally less efficient but more reliable than CLUTCH calculations. Improvements to the CLUTCH methodology that retain the greater efficiency but address identified difficulties are therefore potentially useful to analysts.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2020

Materials Data on P by Materials Project

P is beta Plutonium-like structured and crystallizes in the triclinic P-1 space group. The structure is zero-dimensional and consists of six tetraphosphorus molecules. P is bonded in a 3-coordinate geometry to three equivalent P atoms. All P–P bond lengths are 2.20 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on La2C3 by Materials Project

La2C3 is Plutonium carbide structured and crystallizes in the cubic I-43d space group. The structure is three-dimensional. La3+ is bonded in a 9-coordinate geometry to nine equivalent C2- atoms. There are a spread of La–C bond distances ranging from 2.70–3.00 Å. C2- is bonded in a 5-coordinate geometry to six equivalent La3+ and one C2- atom. The C–C bond length is 1.33 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Lu2C3 by Materials Project

Lu2C3 is Plutonium carbide structured and crystallizes in the cubic I-43d space group. The structure is three-dimensional. Lu3+ is bonded in a 6-coordinate geometry to nine equivalent C2- atoms. There are a spread of Lu–C bond distances ranging from 2.44–2.75 Å. C2- is bonded to six equivalent Lu3+ and one C2- atom to form a mixture of distorted edge, corner, and face-sharing CLu6C trigonal bipyramids. The C–C bond length is 1.35 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sc2C3 by Materials Project

Sc2C3 is Plutonium carbide structured and crystallizes in the cubic I-43d space group. The structure is three-dimensional. Sc2+ is bonded in a 6-coordinate geometry to nine equivalent C+1.33- atoms. There are a spread of Sc–C bond distances ranging from 2.34–2.65 Å. C+1.33- is bonded to six equivalent Sc2+ and one C+1.33- atom to form a mixture of distorted corner, edge, and face-sharing CSc6C trigonal bipyramids. The C–C bond length is 1.34 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Y2C3 by Materials Project

Y2C3 is Plutonium carbide structured and crystallizes in the cubic I-43d space group. The structure is three-dimensional. Y3+ is bonded in a 9-coordinate geometry to nine equivalent C2- atoms. There are a spread of Y–C bond distances ranging from 2.52–2.83 Å. C2- is bonded to six equivalent Y3+ and one C2- atom to form a mixture of distorted edge, face, and corner-sharing CY6C trigonal bipyramids. The C–C bond length is 1.34 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Nd2C3 by Materials Project

Nd2C3 is Plutonium carbide structured and crystallizes in the cubic I-43d space group. The structure is three-dimensional. Nd3+ is bonded in a 9-coordinate geometry to nine equivalent C2- atoms. There are a spread of Nd–C bond distances ranging from 2.64–2.94 Å. C2- is bonded to six equivalent Nd3+ and one C2- atom to form a mixture of distorted edge, corner, and face-sharing CNd6C trigonal bipyramids. The C–C bond length is 1.33 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Pu2C3 by Materials Project

Pu2C3 is Plutonium carbide structured and crystallizes in the cubic I-43d space group. The structure is three-dimensional. Pu3+ is bonded in a 6-coordinate geometry to nine equivalent C2- atoms. There are a spread of Pu–C bond distances ranging from 2.47–2.80 Å. C2- is bonded to six equivalent Pu3+ and one C2- atom to form a mixture of distorted edge, corner, and face-sharing CPu6C trigonal bipyramids. The C–C bond length is 1.39 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ce2C3 by Materials Project

Ce2C3 is Plutonium carbide structured and crystallizes in the cubic I-43d space group. The structure is three-dimensional. Ce3+ is bonded in a 6-coordinate geometry to nine equivalent C2- atoms. There are a spread of Ce–C bond distances ranging from 2.55–2.87 Å. C2- is bonded to six equivalent Ce3+ and one C2- atom to form a mixture of distorted face, edge, and corner-sharing CCe6C trigonal bipyramids. The C–C bond length is 1.37 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Dy2C3 by Materials Project

Dy2C3 is Plutonium carbide structured and crystallizes in the cubic I-43d space group. The structure is three-dimensional. Dy3+ is bonded in a 6-coordinate geometry to nine equivalent C2- atoms. There are a spread of Dy–C bond distances ranging from 2.51–2.82 Å. C2- is bonded to six equivalent Dy3+ and one C2- atom to form a mixture of distorted face, edge, and corner-sharing CDy6C trigonal bipyramids. The C–C bond length is 1.34 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on C(ClF)2 by Materials Project

CCl2F2 is gamma plutonium structured and crystallizes in the orthorhombic Fdd2 space group. The structure is zero-dimensional and consists of eight dichlorodifluoromethane molecules. C4+ is bonded in a tetrahedral geometry to two equivalent Cl1- and two equivalent F1- atoms. Both C–Cl bond lengths are 1.76 Å. Both C–F bond lengths are 1.36 Å. Cl1- is bonded in a single-bond geometry to one C4+ atom. F1- is bonded in a single-bond geometry to one C4+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ho2C3 by Materials Project

Ho2C3 is Plutonium carbide structured and crystallizes in the cubic I-43d space group. The structure is three-dimensional. Ho3+ is bonded in a 6-coordinate geometry to nine equivalent C2- atoms. There are a spread of Ho–C bond distances ranging from 2.50–2.80 Å. C2- is bonded to six equivalent Ho3+ and one C2- atom to form a mixture of distorted corner, edge, and face-sharing CHo6C trigonal bipyramids. The C–C bond length is 1.34 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on H4CN2O by Materials Project

CO(NH2)2 is gamma plutonium-like structured and crystallizes in the tetragonal P-42_1m space group. The structure is zero-dimensional and consists of two urea molecules. C4+ is bonded in a trigonal planar geometry to two equivalent N3- and one O2- atom. Both C–N bond lengths are 1.35 Å. The C–O bond length is 1.28 Å. N3- is bonded in a trigonal planar geometry to one C4+ and two H1+ atoms. Both N–H bond lengths are 1.02 Å. There are two inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one N3- atom. In the second H1+ site, H1+ is bonded in a single-bond geometry to one N3- atom. O2- is bonded in a single-bond geometry to one C4+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on InH36C12S6(IO2)3 by Materials Project

(CH3)12In(SO)6(I)3 is beta Plutonium-derived structured and crystallizes in the trigonal R-3 space group. The structure is zero-dimensional and consists of nine hydriodic acid molecules, thirty-six methane molecules, and three In(SO)6 clusters. In each In(SO)6 cluster, In3+ is bonded in an octahedral geometry to six equivalent O2- atoms. All In–O bond lengths are 2.19 Å. S2- is bonded in a distorted single-bond geometry to one O2- atom. The S–O bond length is 1.56 Å. O2- is bonded in a bent 120 degrees geometry to one In3+ and one S2- atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Rb2O3 by Materials Project

Rb2O3 is Plutonium carbide structured and crystallizes in the cubic I-43d space group. The structure is three-dimensional. Rb is bonded in a 6-coordinate geometry to nine equivalent O atoms. There are a spread of Rb–O bond distances ranging from 2.85–3.18 Å. O is bonded to six equivalent Rb and one O atom to form a mixture of distorted corner, edge, and face-sharing ORb6O pentagonal bipyramids. The O–O bond length is 1.41 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on U2C3 by Materials Project

U2C3 is Plutonium carbide structured and crystallizes in the cubic I-43d space group. The structure is three-dimensional. U6+ is bonded in a 6-coordinate geometry to six equivalent C4- atoms. There are three shorter (2.44 Å) and three longer (2.53 Å) U–C bond lengths. C4- is bonded to four equivalent U6+ and one C4- atom to form a mixture of distorted edge and corner-sharing CU4C trigonal bipyramids. The C–C bond length is 1.44 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on S(ClO)2 by Materials Project

SO2Cl2 is gamma plutonium structured and crystallizes in the orthorhombic Fdd2 space group. The structure is zero-dimensional and consists of eight sulfuryl chloride molecules. S6+ is bonded in a distorted tetrahedral geometry to two equivalent O2- and two equivalent Cl1- atoms. Both S–O bond lengths are 1.43 Å. Both S–Cl bond lengths are 2.03 Å. O2- is bonded in a single-bond geometry to one S6+ atom. Cl1- is bonded in a single-bond geometry to one S6+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Te7Pd20 by Materials Project

Pd20Te7 is beta Plutonium-derived structured and crystallizes in the trigonal R-3 space group. The structure is three-dimensional. there are four inequivalent Pd sites. In the first Pd site, Pd is bonded in a 2-coordinate geometry to three Pd and three equivalent Te atoms. There are two shorter (2.89 Å) and one longer (2.98 Å) Pd–Pd bond lengths. There are a spread of Pd–Te bond distances ranging from 2.67–2.88 Å. In the second Pd site, Pd is bonded in a 10-coordinate geometry to seven Pd and three equivalent Te atoms. There are one shorter (2.73 Å) and three longer (2.95 Å) Pd–Pd bond lengths. All Pd–Te bond lengths are 2.69 Å. In the third Pd site, Pd is bonded in a 3-coordinate geometry to five Pd and three Te atoms. There are a spread of Pd–Pd bond distances ranging from 2.89–2.97 Å. There are a spread of Pd–Te bond distances ranging from 2.70–2.93 Å. In the fourth Pd site, Pd is bonded in a 12-coordinate geometry to eight Pd and four Te atoms. Both Pd–Pd bond lengths are 3.12 Å. There are a spread of Pd–Te bond distances ranging from 2.71–2.90 Å. There are two inequivalent Te sites. In the first Te site, Te is bonded in a cuboctahedral geometry to twelve Pd atoms. In the second Te site, Te is bonded in a 9-coordinate geometry to nine Pd atoms.

36 MATERIALS SCIENCE↗