Two-point theory for the differential self-interrogation Feynman-alpha method

A Feynman-alpha formula has been derived in a two region domain pertaining the stochastic differential self-interrogation (DDSI) method and the differential die-away method (DDAA). Monte Carlo simulations have been used to assess the applicability of the variance to mean through determination of the physical reaction intensities of the physical processes in the two domains. More specifically, the branching processes of the neutrons in the two regions are described by the Chapman - Kolmogorov equation, including all reaction intensities for the various processes, that is used to derive a variance to mean relation for the process. The applicability of the Feynman-alpha or variance to mean formulae are assessed in DDSI and DDAA of spent fuel configurations.Comment: 15 pages, 5 figures. Submitted to EPJ Plu

NBC operation manual including the multi-position add-a-source function

This manual describes the design modifications and operating characteristics of a 200-l-drum neutron coincidence counter. The counter has six shielded banks of {sup 3}He tubes and JSR-11 shift register coincidence electronics. The modified design has a counting efficiency of 19.3%. The neutron counter measures the spontaneous-fission rate from the plutonium, and when this is combined with the plutonium isotopic ratios, we can determine the plutonium mass. The system includes the new multi-position add-a-source (AS) technique that uses a small {sup 252}Cf source to determine the drum`s matrix perturbation to the plutonium assay. The {sup 252}Cf source is measured at three positions on the exterior of the drum to obtain the spatial distribution for the matrix correction. This manual gives the performance and calibration parameters. The matrix corrections by the AS technique are accurate to a few percent for typical applications

Neutron-based measurements for nondestructive assay of minor actinides produced in nuclear power reactors

Because of their impacts on long-term storage of high-level radioactive waste and their value as nuclear fuels, measurement and accounting of the minor actinides produced in nuclear power reactors are becoming significant issues. This paper briefly reviews the commercial nuclear fuel cycle with emphasis on reprocessing plants and key measurement points therein. Neutron signatures and characteristics are compared and contrasted for special nuclear materials (SNMs) and minor actinides (MAs). The paper focuses on application of neutron-based nondestructive analysis (NDA) methods that can be extended for verification of MAs. We describe current IAEA methods for NDA of SNMs and extension of these methods to satisfy accounting requirements for MAs in reprocessing plant dissolver solutions, separated products, and high-level waste. Recommendations for further systems studies and development of measurement methods are also included

Cognitive dysfunction in naturally occurring canine idiopathic epilepsy

Globally, epilepsy is a common serious brain disorder. In addition to seizure activity, epilepsy is associated with cognitive impairments including static cognitive impairments present at onset, progressive seizure-induced impairments and co-morbid dementia. Epilepsy occurs naturally in domestic dogs but its impact on canine cognition has yet to be studied, despite canine cognitive dysfunction (CCD) recognised as a spontaneous model of dementia. Here we use data from a psychometrically validated tool, the canine cognitive dysfunction rating (CCDR) scale, to compare cognitive dysfunction in dogs diagnosed with idiopathic epilepsy (IE) with controls while accounting for age. An online cross-sectional study resulted in a sample of 4051 dogs, of which n = 286 had been diagnosed with IE. Four factors were significantly associated with a diagnosis of CCD (above the diagnostic cut-off of CCDR ≥50): (i) epilepsy diagnosis: dogs with epilepsy were at higher risk; (ii) age: older dogs were at higher risk; (iii) weight: lighter dogs (kg) were at higher risk; (iv) training history: dogs with more exposure to training activities were at lower risk. Impairments in memory were most common in dogs with IE, but progression of impairments was not observed compared to controls. A significant interaction between epilepsy and age was identified, with IE dogs exhibiting a higher risk of CCD at a young age, while control dogs followed the expected pattern of low-risk throughout middle age, with risk increasing exponentially in geriatric years. Within the IE sub-population, dogs with a history of cluster seizures and high seizure frequency had higher CCDR scores. The age of onset, nature and progression of cognitive impairment in the current IE dogs appear divergent from those classically seen in CCD. Longitudinal monitoring of cognitive function from seizure onset is required to further characterise these impairments

In-plant test and evaluation of the neutron collar for verification of PWR fuel assemblies at Resende, Brazil

The neutron-coincidence collar has been evaluated for the measurement of pressurized-water reactor (PWR) fuel assemblies at the Fabrica de Elementos Combustiveis plant in Resende, Brazil. This evaluation was part of the cooperative-bilateral-safeguards technical-exchange program between the United States and Brazil. The neutron collar measures the STVU content per unit length of full fuel assemblies using neutron interrogation and coincidence counting. The STYU content is measured in the passive mode without the AmLi neutron-interrogation source. The extended evaluation took place over a period of 6 months with both scanning and single-zone measurements. The results of the tests gave a coincidence-response standard deviation of 0.7% (sigma = 1.49% for mass) for the active case and 2.5% for the passive case in 1000-s measurement times. The length measurement in the scanning mode was accurate to 0.77%. The accuracies of different calibration methods were evaluated and compared

Treating anxiety after stroke (TASK): the feasibility phase of a novel web-enabled randomised controlled trial

TiDier template items. (DOCX 28 kb

Neutron coincidence counter for MOX fuel pins in storage trays: users' manual

The neutron coincidence counter for measurement of mixed-oxide fuel pins in storage trays is described. The special detector head has been designed so that the detectors, high-voltage junction boxes, and electronics are interchangeable with those of the high-level neutron coincidence counter system. This manual describes the system components and the operation and maintenance of the counter. The counter was developed at Los Alamos National Laboratory for in-plant inspection applications by the International Atomic Energy Agency

A Three Year Study of Special Educator Attrition: WhyThey Leave and Where They Go

With chronic and critical shortages of special education professionals evident throughout the United States, the issues of attrition and retention are on the forefront of analysis. Reasons why special education professionals in Utah left their positions were explored in a three-year study of special education attrition. The causes and patterns of attrition have been analyzed, giving valuable insight into how the loss of qualified special education professionals can be prevented. The most common reason for leaving listed by special education teachers and speech language pathologists was that they “moved out of state”. School psychologists reported “retirement” and “moved out of state” as their two most common reasons for leaving public school positions. The most common reasons for leaving listed by all special education professionals were “moved out of state”, “retired”, and “transferred to general education”. Moving and retiring are most likely not preventable, however, assisting special educators who move to obtain positions as they relocate may be an effective method of retaining them in the field of special education. Preventable attrition such as transferring to general education and changing school districts could be addressed by university faculty and school administrators to better understand why special educators transfer and what can be done to prevent the transfers. This understanding could lead to improved strategies to minimize attrition and promote retention of special education professionals

Special Education Teacher Attrition: How Many AreLeaving? Where Are They Going?

A statewide survey was conducted to determine the number of special education teachers leaving positions in Utah between February 1, 1998 and January 31, 1999. Reasons for leaving were also identified in order to infer possible retention strategies. Findings indicated at 238 special education teachers (9.3%) left their jobs during the one-year period. It was estimated that approximately 9% of this number might have been retained with corrective action. Main reasons for the preventable attrition included transfers to general education and resignations for personal reasons. In-depth research is needed to identify more specific factors underlying special education teacher attrition