Joint application of AI techniques, PRA and disturbance analysis methodology to problems in the maintenance and design of nuclear power plants. Final report

This final report summarizes the accomplishments of a two year research project entitled ``Joint Application of Artificial Intelligence Techniques, Probabilistic Risk Analysis, and Disturbance Analysis Methodology to Problems in the Maintenance and Design of Nuclear Power Plants. The objective of this project is to develop and apply appropriate combinations of techniques from artificial intelligence, (AI), reliability and risk analysis and disturbance analysis to well-defined programmatic problems of nuclear power plants. Reactor operations issues were added to those of design and maintenance as the project progressed

ON THE APPLICATION OF MULTIGROUP DIFFUSION THEORY TO FAST CRITICAL ASSEMBLIES

Multigroup diffusion theory predicts too high a critical mass for small, highly enriched, critical assemblies. An attempt to improve the accuracy of diffusion theory predictions for fast reactors is described. Transport cross sections were adjusted on the basis of multigroup comparison of the Lady Godiva Reactor by diffusion theory and by the asymptotic solution to the Boltzmann equation. In general, the predictions made by the adjusted cross sections were in very good agreement with experiment. The procedure described is not recommended as a panacea but indicates that modifications in elastic transport cross sections may make multigroup diffusion theory more applicable to a wide range of fast reactors. (T.R.H.

SOME PHYSICS CALCULATIONS ON THE PERFORMANCE OF LARGE FAST BREEDER POWER REACTORS

Critical mass, spectrum, breeding ratio, and coolant removal coefficients were calculated for a series of large Pu- U/sup 238/-fueled sodium- cooled fast-breeder power reactors, using a new 16-group cross-section set based in pant on recent miscroscopic cross-section measurements. The parameters studied include reactor size, plutonium isotopic content, and type of structural material. Reactors cooled with Pb - Bi eutectic and those contaiing U/sup 233/- Th fuel were examined. (auath

Safety culture evaluation and asset root cause analysis

This paper examines the role of organizational and management factors in nuclear power plant safety through the use of operating experiences. The ASSET (Assessment of Safety Significant Events Team) reports of thirteen plants (total thirty events) have been analyzed in term of twenty organizational dimensions (factors) identified by Brookhaven National Laboratory and Pennsylvania State University. For three plants detailed results are reported in this paper. The results of thirteen plants are summarized in the form of a table. The study tends to confirm that organizational and management factors play an important role in plant safety. The twenty organizational dimensions and their definitions, in general, were adequate in this study. Formalization, Safety Culture, Technical Knowledge, Training, Roles-Responsibilities and Problem Identification appear to be key organizational factors which influence the safety of nuclear power plants studied

Negative regulation of germination-arrest factor production in Pseudomonas fluorescens WH6 by a putative extracytoplasmic function sigma factor

Pseudomonas fluorescens WH6 secretes a germination-arrest factor (GAF) that we have identified previously as 4-formylaminooxyvinylglycine. GAF irreversibly inhibits germination of the seeds of numerous grassy weeds and selectively inhibits growth of the bacterial plant pathogen Erwinia amylovora. WH6-3, a mutant that has lost the ability to produce GAF, contains a Tn5 insertion in prtR, a gene that has been described previously in some strains of P. fluorescens as encoding a transmembrane regulator. As in these other pseudomonads, in WH6, prtR occurs immediately downstream of prtI, which encodes a protein homologous to extracytoplasmic function (ECF) sigma factors. These two genes have been proposed to function as a dicistronic operon. In this study, we demonstrated that deletion of prtI in WT WH6 had no effect on GAF production. However, deletion of prtI in the WH6-3 mutant overcame the effects of the Tn5 insertion in prtR and restored GAF production in the resulting double mutant. Complementation of the double prtIR mutant with prtI suppressed GAF production. This overall pattern of prtIR regulation was also observed for the activity of an AprX protease. Furthermore, reverse transcription quantitative real-time PCR analysis demonstrated that alterations in GAF production were mirrored by changes in the transcription of two putative GAF biosynthetic genes. Thus, we concluded that PrtI exerted a negative regulatory effect on GAF production, although the mechanism has not yet been determined. In addition, evidence was obtained that the transcription of prtI and prtR in WH6 may be more complex than predicted by existing models

Perspectives on Risk Perceptions

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72341/1/j.1539-6924.1981.tb01409.x.pd

What’s wrong with evolutionary biology?

There have been periodic claims that evolutionary biology needs urgent reform, and this article tries to account for the volume and persistence of this discontent. It is argued that a few inescapable properties of the field make it prone to criticisms of predictable kinds, whether or not the criticisms have any merit. For example, the variety of living things and the complexity of evolution make it easy to generate data that seem revolutionary (e.g. exceptions to well-established generalizations, or neglected factors in evolution), and lead to disappointment with existing explanatory frameworks (with their high levels of abstraction, and limited predictive power). It is then argued that special discontent stems from misunderstandings and dislike of one well-known but atypical research programme: the study of adaptive function, in the tradition of behavioural ecology. To achieve its goals, this research needs distinct tools, often including imaginary agency, and a partial description of the evolutionary process. This invites mistaken charges of narrowness and oversimplification (which come, not least, from researchers in other subfields), and these chime with anxieties about human agency and overall purpose. The article ends by discussing several ways in which calls to reform evolutionary biology actively hinder progress in the field