A. Hogenbirk

ORANGE: a Monte Carlo dose engine for radiotherapy

This study presents data for the verification of ORANGE, a fast MCNP-based dose engine for radiotherapy treatment planning. In order to verify the new algorithm, it has been benchmarked against DOSXYZ and against measurements. For the benchmarking, first calculations have been done using the ICCR-XIII benchmark. Next, calculations have been done with DOSXYZ and ORANGE in five different phantoms (one homogeneous, two with bone equivalent inserts and two with lung equivalent inserts). The calculations have been done with two mono-energetic photon beams (2 MeV and 6 MeV) and two mono-energetic electron beams (10 MeV and 20 MeV). Comparison of the calculated data (from DOSXYZ and ORANGE) against measurements was possible for a realistic 10 MV photon beam and a realistic 15 MeV electron beam in a homogeneous phantom only. For the comparison of the calculated dose distributions and dose distributions against measurements, the concept of the confidence limit (CL) has been used. This concept reduces the difference between two data sets to a single number, which gives the deviation for 90% of the dose distributions. Using this concept, it was found that ORANGE was always within the statistical bandwidth with DOSXYZ and the measurements. The ICCR-XIII benchmark showed that ORANGE is seven times faster than DOSXYZ, a result comparable with other accelerated Monte Carlo dose systems when no variance reduction is used. As shown for XVMC, using variance reduction techniques has the potential for further acceleration. Using modern computer hardware, this brings the total calculation time for a dose distribution with 1.5% (statistical) accuracy within the clinical range (less then 10 min). This means that ORANGE can be a candidate for a dose engine in radiotherapy treatment planning.

New nuclear data libraries for lead and bismuth and their impact on accelerator-driven systems design

Abstract New ENDF-6 formatted nuclear data libraries are presented for 204,206,207,208Pb and 209Bi, for incident neutrons and protons. Apart from the resonance range, which we have adopted from the best available source in existing libraries, the nuclear data evaluations are completely revised in the 0 to 20 MeV energy range and moreover extend up to 200 MeV. This collection of isotopic evaluations is created by using the nuclear model code TALYS with a consistent set of input parameters for all isotopes. The most important nuclear reaction models and parameters needed for our data files are described. We have intended to make these evaluations complete in their description of reaction channels, and use a consistent method to store the data in ENDF-6 format, which includes cross sections, angular distributions, double-differential spectra, discrete and continuum photon production cross sections, and residual production (activation) cross sections including isomers. It is shown that the data present in our libraries give an improved agreement with existing basic experimental data. Moreover, we have validated the new libraries with criticality and shielding benchmarks, where available. We present the results of neutronics calculations on subcritical accelerator-driven systems to show the impact of our new nuclear data on critical reactor parameters, such as keff, when compared with the existing ENDF/B-VI, JENDL, and JEFF libraries.

Benchmark Results for Delayed Neutron Data

We have calculated the effective delayed neutron fraction βeff for 32 benchmark configurations for which measurements have been reported. We use these results to test the delayed neutron data of JEFF‐3.0, ENDF/B‐VI.8, and JENDL‐3.3.

The Use of Molybdenum-Based Ceramic-Metal (CerMet) Fuel for the Actinide Management in LWRs

Abstract The technical and economic aspects of the use of molybdenum depleted in the isotope 95Mo (DepMo) for the transmutation of actinides in a light water reactor are discussed. DepMo has a low neutron absorption cross section and good physical and chemical properties. Therefore, DepMo is expected to be a good inert matrix in ceramic-metal fuel. The costs of the use of DepMo have been assessed, and it was concluded that these costs can be justified for the transmutation of the actinides neptunium, americium, and plutonium.

New Nuclear Data Evaluations for Ca, Sc, Fe, Ge, Pb, and Bi Isotopes

New ENDF‐6 formatted nuclear data evaluations are presented for all natural isotopes of Ca, Sc, Fe, Ge, Pb, and Bi. Apart from the resonance range and low‐energy total cross sections, which we have adopted from the best available library, the nuclear data evaluations are completely revised up to 20 MeV, and moreover are extended up to 200 MeV. This collection of isotopic evaluations, called NRG‐2003, is created with the nuclear‐model code TALYS using input parameters that deviate only slightly, or not at all, from the default values. These model‐input parameters have been tuned to the available experimental data. All evaluations presented here are thus of comparable quality: For each isotope, we use the same set of nuclear models and, equally important, the same set of ENDF‐6 formatting procedures. We have made these evaluations complete in their description of reaction channels. The data, which are stored in a compact way, include cross sections, angular distributions, double‐differential spectra, discre...