[en] The Final Safety Analysis Report (FSAR) for a plutonium facility as required by DOE Orders 5480.23 and 5480.22 has recently been completed and approved. The facility processes and stores radionuclides such as Pu-238, Pu-239, enriched uranium, and to a lesser degree other actinides. This facility produces heat sources. DOE Order 5480.23 and DOE-STD-3009-94 require analysis of different types of accidents (operational accidents such as fires, explosions, spills, criticality events, and natural phenomena such as earthquakes). The accidents that were analyzed quantitatively, or the Evaluation Basis Accidents (EBAs), were selected based on a multi-step screening process that utilizes extensively the Hazards Analysis (HA) performed for the facility. In the HA, specific accident scenarios, with estimated frequency and consequences, were developed for each identified hazard associated with facility operations and activities. Analysis of the EBAs and comparison of their consequences to the evaluation guidelines established the safety envelope for the facility and identified the safety-class structures, systems, and components. This paper discusses the analysis of the fire EBA. This fire accident was analyzed in relatively great detail in the FSAR because of its potential off-site consequences are more severe compared to other events. In the following, a description of the scenario is first given, followed by a brief summary of the methodology for calculating the source term. Finally, the author discuss how a key parameter affecting the source term, the leakpath factor, was determined, which is the focus of this paper

No abstract available

[en] This paper summarizes the results of an assessment of our TRAC-PF1/MOD3 Mark-22 prototype fuel assembly model against single-assembly data obtained from the ''A'' Tank single-assembly tests that were performed at the Savannah River Laboratory. We felt the data characterize prototypic assembly behavior over a range of air-water flow conditions of interest for loss-of-coolant accident (LOCA) calculations. This study was part of a benchmarking effort performed to evaluate and validate a multiple-assembly, full-plant model that is being developed by Los Alamos National Laboratory to study various aspects of the Savannah River plant operating conditions, including LOCA transients, using TRAC-PF1/MOD3 Version 1.10. The results of this benchmarking effort demonstrate that TRAC-PF1/MOD3 is capable pf calculating plenum conditions and assembly flows during conditions thought to be typical of the Emergency Cooling System (ECS) phase of a LOCA. 10 refs., 12 fig

[en] AIM: To report two new, useful computed tomography (CT) signs of the hypovolaemic shock complex (HSC) in adults admitted after blunt abdominal trauma: the halo sign (ring of fluid around a collapsed intra-hepatic inferior vena cava (IVC)), and peripancreatic retroperitoneal fluid. MATERIALS AND METHODS: CT images of 498 consecutive patients admitted after blunt abdominal trauma were reviewed, of which 27 had CT signs of the HSC. The CT images of these 27 patients were analysed. A control group of 101 patients examined using CT for suspected blunt abdominal trauma who did not have the HSC were chosen for comparison. RESULTS: The most common features involved the vascular compartment: diminished IVC diameter (n=27), a positive halo sign (n=21); diminished anteroposterior diameter of the aorta (n=13); and abnormal vascular enhancement (n=10). Peripancreatic retroperitoneal fluid in the absence of pancreatic injury, pancreatitis or pancreatic disease was observed in eight patients. Hollow visceral abnormalities included: diffuse increased mucosal enhancement of both the small and large bowel (n=19); diffuse thickening of the small bowel wall (n=11); and small bowel dilatation (n=7). Solid visceral abnormalities included both decreased and or increased enhancement. Several concomitant intra- and extra-abdominal injuries were also identified. CONCLUSION: In the setting of blunt abdominal trauma, early abdominal CT can show diffuse abnormalities due to the HSC, which occasionally may alert clinicians of unsuspected shock. Recognition of these signs as distinguished from injured viscera is important in order to avoid unnecessary laparotomy. Two new signs are described: the halo sign and peripancreatic retroperitoneal fluid

[en] Bound-continuum processes of the type A(+B→A+B⁺+e or (AB)⁺+e, known as Penning and associative ionization, respectively, are considered. The derivation of the partial-wave Schroedinger equation through the Feshbach projection-operator formalism is reviewed. The potential-energy operator for the general case is then examined carefully and found to be not only collision-energy dependent but also nonlocal. Strict locality is obtained only in the limit of infinite collision energy. Nonlocality due to bound-continuum interaction increases in importance as the collision energy is reduced, and in certain dynamical situations for associative ionization it is found to be predominant. Thus, the common procedure of reducing the bound-continuum interaction to an imaginary local potential becomes suspect and the general validity of the attendant Franck-Condon approximation of vertical electronic transitions is also called into question. Two limiting situations: the high-energy (E→infinity) and the low-energy (E→0) limits: are examined. In the former case, the local potential is isolated and the nonlocal part given explicitly to lowest order; in the latter, the predominant nonlocal part is given explicitly for the case of associative ionization

[en] A dynamical theory of spontaneous emission of molecular collision systems is presented. The theory makes use of specific nuclear trajectories in the time-dependent Schroedinger equation, and hence can be described as semiclassical. Transitions between electronic states are considered. The description of the radiative interaction is effected by photon-dressed electronic states (electronic-field representation) in both the diabatic and adiabatic representations with respect to the field interaction Hamiltonian. In the diabatic representation, one has to deal with two coupled differential--integral equations [Eqs.(21)], whereas in the adiabatic representation, only one [Eq.(75)] is required. The solutions to these equations are sought for using perturbative--interative procedures. It is then found that the diabatic representation, coupled with the stationary-phase approximation, allows an intuitive and pictorial interpretation of the nuclear dynamics involved, but is incapable of providing a tractable computational scheme valid for all frequency regimes. Indeed the stationary-phase approximation is in general only suitable for line-wing regions. The adiabatic representation, on the other hand, yields a unified line-shape expression. The nuclear dynamics in this representation, however, involves motion on complex and nonlocal potentials. An attempt has been made to reconcile this complicated dynamics with the more intuitive approach of a product of Landau-Zener transition probabilities, and also the generalization (to the case involving a quasicontinuum of avoided crossings) of the Miller-George technique of the analytic continuation of classical mechanics

[en] A semiclassical approach based on the propagation of classical trajectories on potential surfaces analytically continued in to the complex plane, together with a discretization procedure, has been developed for the problem of collisional ionization. Based on Franck-Condon considerations the formalism is reduced to that of the two-state approximation. Preionization loss and tunnelling beyond turning points have not been considered. Calculated partial ionization cross sections for the Ar-He system show good agreement with a fully quantum mechanical treatment. (Auth.)

[en] Computations are carried out for the ¹S(6s²)-¹P(6s,6p) coherent laser excitation of ¹³⁷Ba and ¹³⁸Ba in a magnetic field. Results are presented for both the steady-state and time-dependent excited-state populations of the Zeeman-split magnetic sublevels. The quantum-statistical Liouville-equation approach (for the reduced density matrix) is compared to the rate-equations approach. Significant differences are found between these, due to the interference between strongly overlapping lines (especially for ¹³⁷Ba). The time-evolution profiles indicate that the ¹³⁷Ba transient time is much longer than that of ¹³⁸Ba

[en] According to expert estimate, the nuclear power installed capacity in the Pacific Basin region may reach 20 GWe by the year 2010. Facing a phenomenal growth in nuclear power development in the region, the development of high quality nuclear human resources for 'nuclear power ready' developing countries in the Pacific Basin is an important issue at this time. This paper recommends a timely and cost-effective functional training model to the Pacific Basin countries. The model utilizes high quality simulation executed on low cost and readily available PCs to deliver desktop simulator based training programs, as an efficient and economical complement to full scope simulators, which may not be available for initial training until five years after the NPP project has started. The objective is to ensure the goals of self-reliance and the transfer of necessary NPP knowledge at the onset of the project, to build up a technological infrastructure in areas vital for subsequent technical support of the NPP in design, commissioning, and operator training: comprehension of control systems; familiarization of plant responses to accident conditions; man machine interface (MMI) functions and interactions; early guide to commissioning and operating procedures; presentation to safety reviewers, etc. An example of this model is demonstrated with the use of the (1) CANDU 9 (CANada Deuterium Uranium 900 MW Pressurized Heavy Water Reactor) desktop nuclear simulator and (2) CASSIM (CASsiopeia SIMulation development system). (author)

[en] Purpose: To assess the 3D dosimetric accuracy when using a mail-in service for square and stereotactic fields in a clinical environment. Methods: The 3D dosimetry mail-in service (3DDaaS), offered by Modus QA (London, ON), was used to measure dose distributions from a 6 MV beam of a Varian Clinac. Plastic jars filled with radiosensitive ClearView™ gel were received, CT scanned (for registration and density information), irradiated, and then mailed back to the manufacturer for optical CT readout. Three square field irradiations (2×2, 4×4, and 10×10 cm"2) were performed with jars immobilized in a water tank, and a composite small-field stereotactic delivery was performed using an in-air holder. Dosimetric properties of the gel were quantified within the 25–50 Gy dose range using 3D optical attenuation (OA) distributions provided by the manufacturer. OA was normalized to 100% at the position of isocenter, which received 40Gy. Percentage depth dose, profiles, and 3D gamma distributions (3%/1mm criteria) were calculated to quantify feasibility for relative dosimetry. Results: Mean CT-measured density in the central (3×3×3) cm"3 gel region was 40 ± 3 HU, indicating good homogeneity and near-water-equivalence. Measured and calculated central axis doses agreed to within ±3% in the 25–50 Gy dose range. For the square field irradiations, dose profiles agreed to within 1mm. Gamma analysis of the composite irradiation yielded 99.8%, 91.4%, and 79.1% passing rates for regions receiving at least 10, 5, and 2 Gy, respectively, indicating feasibility for use in high-dose regions. Absolute response varied by up to 16% between jars, indicating limitations for absolute dosimetry under the mail-in conditions. Conclusion: 3DDaaS is a novel near-water-equivalent dosimetry system accurate to within 3% dose and 1mm 3D spatial resolution, and is straightforward to use in a clinical setting. Future investigations are warranted to improve dosimeter response in low-dose regions. The authors would like to thank ModusQA (London, ON) for providing the gels and optical readouts used this work. This work was partially funded by NIH P01CA059827.