Publications by authors named "John Till"

Disposal of naturally occurring radioactive material (NORM) and technologically enhanced naturally occurring radioactive material (TENORM) waste in the State of Oregon is prohibited unless it can be demonstrated that the material is nonradioactive as defined by its radionuclide content and potential for emission into the environment. It was determined that a radon flux on the surface of the waste no greater than 0.37 Bq m -2 s -1 would meet this requirement.

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Oil and natural gas fracking waste contains technologically enhanced naturally occurring radioactive material (TENORM) and has increasingly been disposed of in unpermitted landfills, causing concern among regulators and the public about potential exposures. There are numerous issues with TENORM waste, including the lack of Federal regulations on its disposal and the lack of permitted landfills capable of accepting these waste streams. This paper examines two situations in which TENORM was placed in unpermitted landfills, one in Kentucky and one in Oregon.

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Article Synopsis
  • The Santa Susana Field Laboratory (SSFL) was a research facility in California that had some leftover radioactive contamination, especially in one area.
  • In November 2018, a wildfire called the Woolsey Fire burned through the site and researchers studied how smoke and possible contaminants spread to nearby places.
  • After testing the soil in different locations, they found no dangerous levels of radioactive materials from SSFL had moved to new areas because of the fire or past activities there.
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  • Researchers study how radiation affects people's health to make safety rules and keep everyone safe.
  • The Million Person Study looks at health effects from long-term radiation exposure compared to short, intense exposure like what atomic bomb survivors experienced.
  • Many different groups of workers exposed to radiation are included in the study, and important findings about their health risks are being gathered and analyzed.
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Technologically enhanced naturally occurring radioactive material (TENORM) is gaining notoriety in the public sector, as the oil and gas industry looks for disposal locations for its slightly radioactive waste streams. Due in part to both the lack of federal regulations on the disposal of TENORM and the lack of permitted landfills that are designated for TENORM waste, occasionally it ends up being unknowingly placed in municipal landfills. It was alleged that a municipal landfill in Kentucky accepted 1.

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This paper describes how environmental measurement data were used to help quantify the spatial impact and behavior of uranium released to the environment from a uranium manufacturing facility in Apollo, PA. The Apollo facility released enriched uranium to the environment while it operated between 1957 and 1983. Historical monitoring data generated by the site, along with other independent data sources, provided a long-term record documenting the presence and behavior of uranium in the local environment.

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Existing static and kinematic models of concentric tube robots are based on the ordinary differential equations of a static Cosserat rod. In this paper, we provide the first dynamic model for concentric tube continuum robots by adapting the partial differential equations of a dynamic Cosserat rod to describe the coupled inertial dynamics of precurved concentric tubes. This generates an initial-boundary-value problem that can capture robot vibrations over time.

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Article Synopsis
  • The Apollo facility used to turn special uranium into a form for making nuclear fuel from 1957 to 1983.
  • Researchers studied how much uranium was released, how big the particles were, and how they dissolved in the air.
  • They found that most of the uranium came from vents on the roof and that it was mostly large particles, which didn't dissolve much in water.
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Background: Approximately 235,000 military personnel participated at one of 230 U.S. atmospheric nuclear weapons tests from 1945 through 1962.

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A dose-based compliance methodology was developed for Waste Control Specialists, LLC, low-level radioactive waste facility in Andrews, Texas, that allows routine environmental measurement data to be evaluated not only at the end of a year to determine regulatory compliance, but also throughout the year as new data become available, providing a continuous assessment of the facility. The first step in the methodology is a screening step to determine the potential presence of site emissions in the environment, and screening levels are established for each environmental media sampled. The screening accounts for spatial variations observed in background for soil and temporal fluctuations observed in background for air.

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  • The Apollo facility in Pennsylvania turned uranium hexafluoride into uranium oxide from 1957 to 1983 and released some uranium into the air.
  • Most of the uranium was released through roof vents, and a big analysis showed that around 27.9 GBq of uranium was emitted over these years.
  • Tests on air and soil showed that bigger uranium particles were released but dropped off quickly with distance from the facility, meaning closer areas had more uranium in the air than farther away.
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National Council on Radiation Protection and Measurements Commentary 27 examines recent epidemiologic data primarily from low-dose or low dose-rate studies of low linear-energy-transfer radiation and cancer to assess whether they support the linear no-threshold model as used in radiation protection. The commentary provides a critical review of low-dose or low dose-rate studies, most published within the last 10 y, that are applicable to current occupational, environmental, and medical radiation exposures. The strengths and weaknesses of the epidemiologic methods, dosimetry assessments, and statistical modeling of 29 epidemiologic studies of total solid cancer, leukemia, breast cancer, and thyroid cancer, as well as heritable effects and a few nonmalignant conditions, were evaluated.

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Background: The United States (U.S.) conducted 230 above-ground atmospheric nuclear weapons tests between 1945 and 1962 involving over 250,000 military personnel.

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Background: This article summarizes the methodology, results, and challenges of the reconstruction of red bone marrow and male breast doses for a 1982-person sub-cohort of ∼114,270 U.S. military veterans who participated in eight atmospheric nuclear weapons tests between 1945 and 1962.

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Purpose: Scientific Committee 6-9 was established by the National Council on Radiation Protection and Measurements (NCRP), charged to provide guidance in the derivation of organ doses and their uncertainty, and produced a report, NCRP Report No. 178, Deriving Organ Doses and their Uncertainty for Epidemiologic Studies with a focus on the Million Person Study of Low-Dose Radiation Health Effects (MPS). This review summarizes the conclusions and recommendations of NCRP Report No.

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With the increased use of 3-dimensional dental imaging and cone beam computed tomography in dentistry, dental practitioners should understand and effectively communicate the associated radiation doses and risks to patients. This article will explain dose and risk of cone beam computed tomography technology, drawing on 3 decades of experience in communicating human health risk to the public from radiation exposure in the environment. This report provides examples of dose and risk metrics and comparisons to help providers understand the risk to their patients and to effectively communicate that risk.

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Background: Accurate dosimetry is key to deriving the dose response from radiation exposure in an epidemiological study. It becomes increasingly important to estimate dose as accurately as possible when evaluating low dose and low dose rate as the calculation of excess relative risk per Gray (ERR/Gy) is very sensitive to the number of excess cancers observed, and this can lead to significant errors if the dosimetry is of poor quality. By including an analysis of the dosimetry, we gain a far better appreciation of the robustness of the work from the standpoint of its value in supporting the shape of the dose response curve at low doses and low dose rates.

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Both red bone marrow and male breast doses with associated uncertainty have been reconstructed for a 1,982-person subset of a cohort of 114, 270 military personnel (referred to as "atomic veterans") who participated in U.S. atmospheric nuclear weapons testing from 1945 to 1962.

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Health effects following low doses of ionizing radiation are uncertain. Military veterans at the Nevada test site (NTS) during the SMOKY atmospheric nuclear weapons test in 1957 were reported to be at increased risk for leukemia in 1979, but this increase was not evaluated with respect to radiation dose. The SMOKY test was one of 30 tests in 1957 within the PLUMBBOB test series.

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In this paper, we present the design, construction, and control of a six-degree-of-freedom (DOF), 12 mm diameter, parallel continuum manipulator with a 2-DOF, cable-driven grasper. This work is a proof-of-concept first step towards miniaturization of this type of manipulator design to provide increased dexterity and stability in confined-space surgical applications, particularly for endoscopic procedures. Our robotic system consists of six superelastic NiTi (Nitinol) tubes in a standard Stewart-Gough configuration and an end effector with 180 degree motion of its two jaws.

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Radiation dose reconstruction systems for large-scale epidemiological studies are sophisticated both in providing estimates of dose and in representing dosimetry uncertainty. For example, a computer program was used by the Hanford Thyroid Disease Study to provide 100 realizations of possible dose to study participants. The variation in realizations reflected the range of possible dose for each cohort member consistent with the data on dose determinates in the cohort.

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Article Synopsis
  • The Million Worker Study (MWS) investigates the cancer risk associated with long-term radiation exposure among one million U.S. radiation workers and veterans, differing from studies on atomic bomb survivors who experienced immediate exposure.
  • The study aims to evaluate not only cancer mortality but also other health outcomes like cardiovascular and cerebrovascular diseases, highlighting the importance of accurately estimating radiation doses absorbed by specific organs over a 70-year span.
  • A scientific committee is working on a comprehensive report on organ dose assessment, focusing on uncertainty analysis and applying guidelines to improve the accuracy of the study's dosimetry methods.
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The suitability of a new facility in terms of potential impacts from routine and accidental releases is typically evaluated using conservative models and assumptions to assure dose standards are not exceeded. However, overly conservative dose estimates that exceed target doses can result in unnecessary and costly facility design changes. This paper examines one such case involving the U.

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