RELAP5 code development and assessment at the Savannah River Site

Over the past year, the focus of RELAP5 use at the Savannah River Site has been on code applications to reactor accidents having a direct bearing on setting power limits, with a lesser emphasis on code development. In the applications task, RELAP5/MOD2.5 has been used to predict the thermal-hydraulic system response to large break loss of coolant accidents and to provide boundary conditions for a detailed fuel assembly code. This paper describes the significant phenomena affecting the ability of RELAP5 to perform the system calculations, the benchmarking work completed to validate the application of RELAP5 to Savannah River Site reactors, and the results of the system calculations. This paper will also describe the code and model development effort and will describe briefly certain significant gains

Two-Scale Kirchhoff Theory: Comparison of Experimental Observations With Theoretical Prediction

We introduce a non-perturbative two scale Kirchhoff theory, in the context of light scattering by a rough surface. This is a two scale theory which considers the roughness both in the wavelength scale (small scale) and in the scales much larger than the wavelength of the incident light (large scale). The theory can precisely explain the small peaks which appear at certain scattering angles. These peaks can not be explained by one scale theories. The theory was assessed by calculating the light scattering profiles using the Atomic Force Microscope (AFM) images, as well as surface profilometer scans of a rough surface, and comparing the results with experiments. The theory is in good agreement with the experimental results.Comment: 6 pages, 8 figure

The effect of baseline metabolic rate on pulmonary O₂ uptake kinetics during very heavy intensity exercise in boys and men

addresses: Children's Health and Exercise Research Centre, College of Life and Environmental Sciences, University of Exeter, UK.Copyright © 2012 Elsevier. NOTICE: this is the author’s version of a work that was accepted for publication in Respiratory Physiology and Neurobiology. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Respiratory Physiology and Neurobiology, 2012, 180 (2-3), pp. 223 – 229 DOI: 10.1016/j.resp.2011.11.013This study tested the hypothesis that pulmonary VO₂ kinetics would be slowed during 'work-to-work' exercise in adults but not in children. Eight boys (mean age=12.5 ± 0.5 years) and nine men completed very heavy step transitions initiated from either 'unloaded' pedalling (U→VH) or unloaded-to-moderate cycling (i.e. U→M to M→VH). The phase II τ was significantly (p<0.05) lengthened in M→VH compared to U→M and U→VH in boys (30 ± 5 vs. 19 ± 5 vs. 21 ± 5 s) and men (49 ± 14 vs. 30 ± 5 vs. 34 ± 8 s). In U→VH, a greater relative VO₂ slow component temporally coincided with an increased linear iEMG slope in men compared boys (VO₂ slow component: 16 ± 3 vs. 11 ± 4%; iEMG slope: 0.19 ± 0.24 vs. -0.06 ± 0.14%, p<0.05). These results suggest that an age-linked modulation of VO₂ kinetics might be influenced by alterations in muscle fibre recruitment following the onset of exercise

Aerobic Function and Muscle Deoxygenation Dynamics during Ramp Exercise in Children

PURPOSE:To characterise changes in deoxyhemoglobin ([HHb]) response dynamics in boys and girls during ramp incremental exercise to investigate whether the reduced peak oxygen uptake (peakV˙O2) in girls is associated with a poorer matching of muscle O2 delivery to muscle O2 utilisation, as evidenced by a more rapid increase in [HHb].METHODS:52 children (31 boys, 9.9 ± 0.6 years, 1.38 ± 0.07 m, 31.70 ± 5.78 kg) completed ramp incremental exercise on a cycle ergometer during which pulmonary gas exchange and muscle oxygenation parameters were measured.RESULTS:When muscle [HHb] was expressed against absolute work rate and V˙O2, girls had an earlier change in [HHb] as evidenced by the lower c/d parameter (Girls: 54 ± 20 W vs Boys: 67 ± 19 W, P=0.023; Girls: 0.82 ± 0.28 L·min vs. Boys: 0.95 ± 0.19 L·min, P=0.055) and plateau (Girls: 85 ± 12 W vs. Boys: 99 ± 18 W, P=0.031; Girls: 1.02 ± 0.25 L·min vs. Boys: 1.22 ± 0.28 L·min, P=0.014). However, when expressed against relative work-rate or V˙O2, there were no sex differences in [HHb] response dynamics (all P&#62;0.20). Significant correlations were observed between absolute and fat-free mass normalised peak V˙O2 and the HHb c/d and plateau parameters when expressed against absolute work-rate or V˙O2. Furthermore, when entered into a multiple regression model, the [HHb] plateau against absolute V˙O2 contributed 12% of the variance in peak V˙O2 after adjusting for fat-free mass, gas exchange threshold, and body fatness (model R =0.81, P&#60;0.001).CONCLUSION:The sex-difference in peak V˙O2 in 9-10 year old children is, in part, related to sex-specific changes in muscle O2 extraction dynamics during incremental exercise

Synergism/complementarity of recombinant adenoviral vectors and other vaccination platforms during induction of protective immunity against malaria

The lack of immunogenicity of most malaria antigens and the complex immune responses required for achieving protective immunity against this infectious disease have traditionally hampered the development of an efficient human malaria vaccine. The current boom in development of recombinant viral vectors and their use in prime-boost protocols that result in enhanced immune outcomes have increased the number of malaria vaccine candidates that access pre-clinical and clinical trials. In the frontline, adenoviruses and poxviruses seem to be giving the best immunization results in experimental animals and their mutual combination, or their combination with recombinant proteins (formulated in adjuvants and given in sequence or being given as protein/virus admixtures), has been shown to reach unprecedented levels of anti-malaria immunity that predictably will be somehow reproduced in the human setting. However, all this optimism was previously seen in the malaria vaccine development field without many real applicable results to date. We describe here the current state-of-the-art in the field of recombinant adenovirus research for malaria vaccine development, in particular referring to their use in combination with other immunogens in heterologous prime-boost protocols, while trying to simultaneously show our contributions and point of view on this subject

Generating and repairing genetically programmed DNA breaks during immunoglobulin class switch recombination

Adaptive immune responses require the generation of a diverse repertoire of immunoglobulins (Igs) that can recognize and neutralize a seemingly infinite number of antigens. V(D)J recombination creates the primary Ig repertoire, which subsequently is modified by somatic hypermutation (SHM) and class switch recombination (CSR). SHM promotes Ig affinity maturation whereas CSR alters the effector function of the Ig. Both SHM and CSR require activation-induced cytidine deaminase (AID) to produce dU:dG mismatches in the Ig locus that are transformed into untemplated mutations in variable coding segments during SHM or DNA double-strand breaks (DSBs) in switch regions during CSR. Within the Ig locus, DNA repair pathways are diverted from their canonical role in maintaining genomic integrity to permit AID-directed mutation and deletion of gene coding segments. Recently identified proteins, genes, and regulatory networks have provided new insights into the temporally and spatially coordinated molecular interactions that control the formation and repair of DSBs within the Ig locus. Unravelling the genetic program that allows B cells to selectively alter the Ig coding regions while protecting non-Ig genes from DNA damage advances our understanding of the molecular processes that maintain genomic integrity as well as humoral immunity

Muscle Oxygen Changes following Sprint Interval Cycling Training in Elite Field Hockey Players

This study examined the effects of Sprint Interval Cycling (SIT) on muscle oxygenation kinetics and performance during the 30-15 intermittent fitness test (IFT). Twenty-five women hockey players of Olympic standard were randomly selected into an experimental group (EXP) and a control group (CON). The EXP group performed six additional SIT sessions over six weeks in addition to their normal training program. To explore the potential training-induced change, EXP subjects additionally completed 5 x 30s maximal intensity cycle testing before and after training. During these tests near-infrared spectroscopy (NIRS) measured parameters; oxyhaemoglobin + oxymyoglobin (HbO2+ MbO2), tissue deoxyhaemoglobin + deoxymyoglobin (HHb+HMb), total tissue haemoglobin (tHb) and tissue oxygenation (TSI %) were taken. In the EXP group (5.34±0.14 to 5.50±0.14m.s-1) but not the CON group (pre = 5.37± 0.27 to 5.39±0.30m.s-1) significant changes were seen in the 30-15IFTperformance. EXP group also displayed significant post-training increases during the sprint cycling: ΔTSI (-7.59±0.91 to -12.16±2.70%); ΔHHb+HMb (35.68±6.67 to 69.44 ±26.48μM.cm); and ΔHbO2+ MbO2 (-74.29±13.82 to -109.36±22.61μM.cm). No significant differences were seen in ΔtHb (-45.81±15.23 to -42.93±16.24). NIRS is able to detect positive peripheral muscle oxygenation changes when used during a SIT protocol which has been shown to be an effective training modality within elite athletes

Computational Analysis of the SRS Phase III Salt Disposition Alternatives

Completion of the Phase III evaluation and comparison of salt disposition alternatives was supported with enhanced computer models and analysis for each case on the ''short list'' of four options. SPEEDUP(TM) models and special purpose models describing mass and energy balances and flow rates were developed and used to predict performance and production characteristics for each of the options. Results from the computational analysis were a key part of the input used to select a primary and an alternate salt disposition alternative

SRS supplemental safety system injection (gas pressurizer) test

An evaluation and validation of an existing version of the RELAP5 thermal hydraulics computer code was undertaken for the purpose of certification for use in the new production reactor - heavy water reactor (NPR-HWR) program. This version of the code was RELAP5/MOD3 Version 5q, designated for the purposes of the NPR-HWR program as RELAP5/NPR Version 0. As part of the evaluation and assessment, test data from theSRS Supplemental Safety System Injection (Gas Pressurizer) was used to verify and assess the ability of RELAP5/NPR Version 0 to perform thermal-hydraulic model analysis using the test data. Specifically, the assessment determines RELAP5/NPR Version 0 capability in modeling sudden depressurization phenomena. Two RELAP5/NPR Version 0 components (pipe and accumulator) were used to compare calculated pressure and temperature against test data. The code deficiencies are a temperature clamp in the accumulator component prevents the gas temperature from going below [minus]9[degrees]F, and RELAP5 accumulator and pipe components wall-to-fluid heat transfer correlation and interfacial vapor heat transfer correlation need substantial improvement. Only the code pipe component calculated pressures and temperatures within the specified 10 percent accuracy