Frequency response testing at Experimental Breeder Reactor II using discrete-level periodic signals

The Experimental Breeder Reactor 2 (EBR-2) reactivity-to-power frequency-response function was measured with pseudo-random, discrete-level, periodic signals. The reactor power deviation was small with insignificant perturbation of normal operation and in-place irradiation experiments. Comparison of results with measured rod oscillator data and with theoretical predictions show good agreement. Moreover, measures of input signal quality (autocorrelation function and energy spectra) confirm the ability to enable this type of frequency response determination at EBR-2. Measurements were made with the pseudo-random binary sequence, quadratic residue binary sequence, pseudo-random ternary sequence, and the multifrequency binary sequence. 10 refs., 7 figs., 3 tabs

Dynamic analysis of the EBR-II plant with the DSNP-ND simulation package

Development and initial testing have been completed for a special version of the DSNP simulation language software package, DSNP-ND, which simulates EBR-II based on the models of the primary system components used in the NATDEMO program. Preliminary results are included for a comparison with an original NATDEMO prediction for the SHRT-45 transient. 7 refs

Risk management activities at the DOE Class A reactor facilities

The probabilistic risk assessment (PRA) and risk management group of the Association for Excellence in Reactor Operation (AERO) develops risk management initiatives and standards to improve operation and increase safety of the DOE Class A reactor facilities. Principal risk management applications that have been implemented at each facility are reviewed. The status of a program to develop guidelines for risk management programs at reactor facilities is presented

SRS K-Reactor PRA LOCA analyses using best-estimate methods

The thermal-hydraulic system computer code RELAP5/MOD2.5 was used to investigate the response of the primary cooling system during loss-of-coolant accidents (LOCAs) at the Savannah River Site (SRS) K-Reactor. In contrast to the conservative safety analyses performed to support the restart of K-Reactor, the assumptions and boundary conditions used in the analyses described in this paper were carefully selected to reflect best-estimate values wherever possible. The results of the calculations indicate that, for a small break LOCA, one functional emergency cooling system pumping source combined with one operational injection path will maintain core cooling. For a large break LOCA, one additional injection path is needed. The incorporation of these results into the latest SRS K-Reactor Probabilistic Risk Assessment (PRA) contributed significantly to the reduction in severe core melt frequency over the previous version

Plutonium removal limit for the disposition of plutonium-bearing materials

Recent changes in world politics have resulted in the United States reducing its nuclear weapons and stopping plutonium production. Prior plutonium production, dismantling warheads, and decontamination and decommissioning some facilities have produced plutonium-bearing materials which must continue to be managed. As each lot of material is processed, the processor must decide whether to remove the plutonium before discarding the material or to discard it without plutonium removal. DOE has developed a new method of making this decision, called the Plutonium Removal Limit System (PRLS). The system is based on defining a plutonium concentration above which the cost of disposing of plutonium-bearing materials will be less if plutonium is recovered and below which the cost will be less if plutonium is discarded (following suitable waste treatment). This method minimizes the overall cost to DOE for disposing of the existing inventory of plutonium-bearing materials. The method was used to analyze the plutonium-discard limit for all categories of plutonium-bearing materials currently at each site. This analysis indicated the need to standardize the way sites make the remove-versus-discard decision. For this purpose, a set of departmental plutonium removal limits was developed. DOE expects to approve implementing this new method at all facilities handling plutonium-bearing material in FY 93

Betile - Museo regionale dell'arte nuragica e dell'arte contemporanea del Mediterraneo.

Progetto finalista del concorso internazionale per il Betile, Museo regionale dell'arte nuragica e dell'arte contemporanea del Mediterraneo. In: "Sardegna: i paesaggi del futuro”, allegato al n. 899 della rivista Domus, gennaio 200

International Competition Museo Betile_Mostra Progetti Finalisti_2006

MOSTRA DEI 9 PROGETTI FINALISTI DEL CONCORSO DI PROGETTAZIONE PER LA REALIZZAZIONE DEL MUSEO DELL’ARTE NURAGICA E DELL’ARTE CONTEMPORANEA DEL MEDITERRANE

Theoretical modeling of crevice and pitting corrosion processes in relation to corrosion of radioactive waste containers

A mathematical and numerical model for evaluation of crevice and pitting corrosion in radioactive waste containers is presented. The model considers mass transport, mass transfer at the metal/solution interface, and chemical speciation in the corrosion cavity. The model is compared against experimental data obtained in artificial crevices. Excellent agreement is found between modeled and experimental values. The importance of full consideration of complex ion formation in the aqueous solution is emphasized and illustrated. 10 refs., 5 figs

PREPP (Process Experimental Pilot Plant) rotary kiln seals: Problem and resolution

The Process Experimental Pilot Plant (PREPP) is a facility designed to demonstrate processing of low level chemical and transuranic hazardous waste. The plant includes equipment for handling the incoming waste containers, shredding, incineration and cooling the waste, grouting the residue and scrubbing and filtration of the off gas. The process incinerator is a rotary kiln approximately 8-{1/2} ft diameter and 25 ft long with a rotary seal assembly at each end. Each seal assembly consists of a primary, secondary and tertiary seal, with a positive air pressure between primary and secondary seals to prevent out-leakage from the kiln. The kiln operates at 0.5 inch water negative pressure. From the very outset the kiln seals exhibited excessive drag which taxed the kiln drive capacity and excessive in-leakage which limited kiln temperature. An engineering evaluation concluded that the original seals supplied by the kiln vendor could not accommodate expansion and centerline shift of the kiln resulting from heatup of the kiln and its support system. A totally new concept kiln seal design has been generated to replace the (modified) original seals. This new seal system has been designed to provide a very tight long lasting seal which will accommodate the 1.5 inch axial shift and up to 1 inch radial movement of the kiln shell. Design lifetime of the seal is 10,000 operating hours between major maintenance services while maintaining an acceptable leak rate hot or cold, rotating or stopped. The design appears adaptable to any size kiln and is suitable for retrofit to existing kilns. A one-third scale prototype seal assembly is being built to verify the concept prior to construction of the 10 ft diameter seals for the PREPP rotary kiln. 4 figs