A perturbation-based susbtep method for coupled depletion Monte-Carlo codes

Coupled Monte Carlo (MC) methods are becoming widely used in reactor physics analysis and design. Many research groups therefore, developed their own coupled MC depletion codes. Typically, in such coupled code systems, neutron fluxes and cross sections are provided to the depletion module by solving a static neutron transport problem. These fluxes and cross sections are representative only of a specific time-point. In reality however, both quantities would change through the depletion time interval. Recently, Generalized Perturbation Theory (GPT) equivalent method that relies on collision history approach was implemented in Serpent MC code. This method was used here to calculate the sensitivity of each nuclide and reaction cross section due to the change in concentration of every isotope in the system. The coupling method proposed in this study also uses the substep approach, which incorporates these sensitivity coefficients to account for temporal changes in cross sections. As a result, a notable improvement in time dependent cross section behavior was obtained. The method was implemented in a wrapper script that couples Serpent with an external depletion solver. The performance of this method was compared with other existing methods. The results indicate that the proposed method requires substantially less MC transport solutions to achieve the same accuracy

Development of a Knowledge Management System for Energy Driven by Public Feedback

The Nuclear Engineering Department at the University of California, Berkeley, in collaboration with the Industrial Engineering and Operations Research Department and the University of Lincoln in the United Kingdom, is proposing to create an open web platform that makes high-quality scientific data on energy sources readily available, assembles those data into metrics more suitable to the general public’s knowledge and interest (e.g. impact on the family’s budget or green house gas emission), and visually renders such information in a straightforward manner

Investigations on Repository Near-Field Thermal Modeling - Repository Science/Thermal Load Management & Design Concepts (M41UF033302) Rev.1

The various layers of material from the waste package (such as components of the engineered barrier system and the host rock surface) to a given distance within the rock wall at a given distance can be described as concentric circles with varying thermal properties (see Figure 5.1-1). The selected model approach examines the contributions of the waste package, axial waste package neighbors and lateral neighboring emplacement drifts (see Section 5.2.1 and Appendix H, Section 2). In clay and deep borehole media, the peak temperature is driven by the central waste package whereas, in granite and salt, the contribution to the temperature rise by adjacent (lateral) waste packages in drift or emplacement borehole lines is dominant at the time of the peak temperature. Mathematical models generated using Mathcad software provide insight into the effects of changing waste package spacing for six waste forms, namely UOX, MOX, co-extraction, new extraction, E-Chem ceramic and E-Chem metal in four different geologic media (granite, clay, salt and deep borehole). Each scenario includes thermal conductivity and diffusivity for each layer between the waste package and the host rock, dimensions of representative repository designs (such as waste package spacing, drift or emplacement borehole spacing, waste package dimensions and layer thickness), and decay heat curves generated from knowledge of the contents of a given waste form after 10, 50, 100 and 200 years of surface storage. Key results generated for each scenario include rock temperature at a given time calculated at a given radius from the central waste package (Section 5.2.1 and Appendix H, Section 3), the corresponding temperature at the interface of the waste package and EBS material, and at each EBS layer in between (Section 5.2.2 and Appendix H, Section 4). This information is vital to understand the implications of repository design (waste package capacity, surface storage time, waste package spacing, and emplacement drift or borehole spacing) by comparing the peak temperature to the thermal limits of the concentric layers surrounding the waste package; specifically 100 C for the bentonite buffer in granite and clay repositories, 100 C for rock wall in a clay repository and 200 C at the rock wall for a salt repository. These thermal limits are both preliminary and approximate, and serve as a means to evaluate design options rather than determining compliance for licensing situations. The thermal behavior of a salt repository is more difficult to model because it is not a concentric geometry and because the crushed salt backfill initially has a much higher thermal resistance than intact salt. Three models were investigated, namely a waste package in complete contact with crushed salt, secondly a waste package in contact with intact salt, and thirdly a waste package in contact with 75% intact and 25% crushed salt. The latter model best depicts emplacement of a waste package in the corner of an intact salt alcove and subsequently covered with crushed salt backfill to the angle of repose. The most conservative model (crushed salt) had temperatures much higher than the other models and although bounding, is too conservative to use. The most realistic model (75/25) had only a small temperature difference from the simplest (non-conservative, intact salt) model, and is the one chosen in this report (see Section 5.2.3). A trade-study investigating three key variables (surface storage time, waste package capacity and waste package spacing) is important to understand and design a repository. Waste package heat can be reduced by storing for longer periods prior to emplacement, or by reducing the number of assemblies or canisters within that waste package. Waste package spacing can be altered to optimize the thermal load without exceeding the thermal limits of the host rock or EBS components. By examining each of these variables, repository footprint (and therefore cost) can be optimized. For this report, the layout was fixed for each geologic medium based on prior published designs in the international community, but it will be varied in future work. Section 5.2.4 summarizes the conclusions based on varying two of the three parameters (storage time and waste package capacity), and the results are shown in Appendix H, Sections 5 and 6

Investigations on Repository Near-Field Thermal Modeling - Repository Science/Thermal Load Management & Design Concepts (M41UF033302)

The various layers of material from the waste package (such as components of the engineered barrier system and the host rock surface) to a given distance within the rock wall at a given distance can be described as concentric circles with varying thermal properties (see Figure 5.1-1). The selected model approach examines the contributions of the waste package, axial waste package neighbors and lateral neighboring emplacement drifts (see Section 5.2.1 and Appendix H, Section 2). In clay and deep borehole media, the peak temperature is driven by the central waste package whereas, in granite and salt, the contribution to the temperature rise by adjacent (lateral) waste packages in drift or emplacement borehole lines is dominant at the time of the peak temperature. Mathematical models generated using Mathcad software provide insight into the effects of changing waste package spacing for six waste forms, namely UOX, MOX, co-extraction, new extraction, E-Chem ceramic and E-Chem metal in four different geologic media (granite, clay, salt and deep borehole). Each scenario includes thermal conductivity and diffusivity for each layer between the waste package and the host rock, dimensions of representative repository designs (such as waste package spacing, drift or emplacement borehole spacing, waste package dimensions and layer thickness), and decay heat curves generated from knowledge of the contents of a given waste form after 10, 50, 100 and 200 years of surface storage. Key results generated for each scenario include rock temperature at a given time calculated at a given radius from the central waste package (Section 5.2.1 and Appendix H, Section 3), the corresponding temperature at the interface of the waste package and EBS material, and at each EBS layer in between (Section 5.2.2 and Appendix H, Section 4). This information is vital to understand the implications of repository design (waste package capacity, surface storage time, waste package spacing, and emplacement drift or borehole spacing) by comparing the peak temperature to the thermal limits of the concentric layers surrounding the waste package; specifically 100 C for the bentonite buffer in granite and clay repositories, 100 C for rock wall in a clay repository and 200 C at the rock wall for a salt repository. These thermal limits are both preliminary and approximate, and serve as a means to evaluate design options rather than determining compliance for licensing situations. The thermal behavior of a salt repository is more difficult to model because it is not a concentric geometry and because the crushed salt backfill initially has a much higher thermal resistance than intact salt. Three models were investigated, namely a waste package in complete contact with crushed salt, secondly a waste package in contact with intact salt, and thirdly a waste package in contact with 75% intact and 25% crushed salt. The latter model best depicts emplacement of a waste package in the corner of an intact salt alcove and subsequently covered with crushed salt backfill to the angle of repose. The most conservative model (crushed salt) had temperatures much higher than the other models and although bounding, is too conservative to use. The most realistic model (75/25) had only a small temperature difference from the simplest (non-conservative, intact salt) model, and is the one chosen in this report (see Section 5.2.3). A trade-study investigating three key variables (surface storage time, waste package capacity and waste package spacing) is important to understand and design a repository. Waste package heat can be reduced by storing for longer periods prior to emplacement, or by reducing the number of assemblies or canisters within that waste package. Waste package spacing can be altered to optimize the thermal load without exceeding the thermal limits of the host rock or EBS components. By examining each of these variables, repository footprint (and therefore cost) can be optimized. For this report, the layout was fixed for each geologic medium based on prior published designs in the international community, but it will be varied in future work. Section 5.2.4 summarizes the conclusions based on varying two of the three parameters (storage time and waste package capacity), and the results are shown in Appendix H, Sections 5 and 6

Energy Return on Investment - Fuel Recycle

This report provides a methodology and requisite data to assess the potential Energy Return On Investment (EROI) for nuclear fuel cycle alternatives, and applies that methodology to a limited set of used fuel recycle scenarios. This paper is based on a study by Lawrence Livermore National Laboratory and a parallel evaluation by AREVA Federal Services LLC, both of which were sponsored by the DOE Fuel Cycle Technologies (FCT) Program. The focus of the LLNL effort was to develop a methodology that can be used by the FCT program for such analysis that is consistent with the broader energy modeling community, and the focus of the AREVA effort was to bring industrial experience and operational data into the analysis. This cooperative effort successfully combined expertise from the energy modeling community with expertise from the nuclear industry. Energy Return on Investment is one of many figures of merit on which investment in a new energy facility or process may be judged. EROI is the ratio of the energy delivered by a facility divided by the energy used to construct, operate and decommission that facility. While EROI is not the only criterion used to make an investment decision, it has been shown that, in technologically advanced societies, energy supplies must exceed a minimum EROI. Furthermore, technological history shows a trend towards higher EROI energy supplies. EROI calculations have been performed for many components of energy technology: oil wells, wind turbines, photovoltaic modules, biofuels, and nuclear reactors. This report represents the first standalone EROI analysis of nuclear fuel reprocessing (or recycling) facilities

Quantum efficiency measurement system for large area CsI photodetectors

A proximity focusing freon/CsI RICH detector has been built for kaon physics at Thomas Jefferson National Accelerator Facility (TJNAF or Jefferson Lab), Hall A. The Cherenkov photons are detected by a UV photosensitive CsI film which has been obtained by vacuum evaporation. A dedicated evaporation facility for large area photocathodes has been built for this task. A measuring system has been built to allow the evaluation of the absolute quantum efficiency (QE) just after the evaporation. The evaporation facility is described here, as well as the quantum efficiency measurement device. Results of the QE on-line measurements, for the first time on large area photocathodes, are reported

Extra-osseous osteochondroma-like soft tissue mass of the patello-femoral space

BACKGROUND: Extraskeletal cartilaginous tumors are uncommon. Osteochondromas usually arise from the metaphyseal region of the growing skeleton. CASE PRESENTATION: A 53 year old man presented with a three years history of anterior knee pain and inability to flex his knee more than 90°. Clinical examination and imaging studies revealed a nodular calcific mass in the anterior portion of the knee, displacing the medial portion of the patellar tendon. Following excision, histopathology confirmed the diagnosis of extra-osseous osteochondroma-like soft tissue mass, with no recurrence 24 months after surgery. CONCLUSION: An integrated clinical-pathologic diagnosis helps to clarify the nature of extraskeletal cartilaginous tumors that can arise at unusual anatomic site. Complete local surgical excision is the management of choice

Performance and results of the RICH detector for kaon physics in Hall A at Jefferson Lab

Abstract A proximity focusing RICH detector has been constructed for the hadron High Resolution Spectrometer (HRS) of Jefferson Lab Experimental Hall-A. This detector is intended to provide excellent hadron identification up to a momentum of 2.5 GeV / c . The RICH uses a 15 mm thick liquid perfluorohexane radiator in proximity focusing geometry to produce Cherenkov photons traversing a 100 mm thick proximity gap filled with pure methane and converted into electrons by a thin film of CsI deposited on the cathode plane of a MWPC. The detector has been successfully employed in the fixed target, high luminosity and high resolution hypernuclear spectroscopy experiment. With its use as a kaon identifier in the 2 GeV / c region, the very large contribution from pions and protons to the hypernuclear spectrum was reduced to a negligible level. The basic parameters and the resulting performance obtained during the experiment are reported in this paper

Spectroscopy of Lambda-9Li by electroproduction

In the absence of accurate data on the free two-body hyperon-nucleon interaction, the spectra of hypernuclei can provide information on the details of the effective hyperon-nucleon interaction. Electroproduction of the hypernucleus Lambda-9Li has been studied for the first time with sub-MeV energy resolution in Hall A at Jefferson Lab on a 9Be target. In order to increase the counting rate and to provide unambiguous kaon identification, two superconducting septum magnets and a Ring Imaging CHerenkov detector (RICH) were added to the Hall A standard equipment. The cross section to low-lying states of Lambda-9Li is concentrated within 3 MeV of the ground state and can be fitted with four peaks. The positions of the doublets agree with theory while a disagreement could exist with respect to the relative strengths of the peaks in the doublets. A Lambda separation energy of 8.36 +- 0.08 (stat.) +- 0.08 (syst.) MeV was measured, in agreement with an earlier experiment.Comment: 14 pages, 8 figure