TPM-B - Risk Assessment Woodrow Wilson B 14:30 - 17:30
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| Chair(s): Armin Ansari
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TPM-B.1
14:30 Optimized Novel Shielding for Van Allen Belt Radiation S McDonell*, North Carolina State University
; S Hanson, North Carolina State University; R Pudelko, North Carolina State University; RB Hayes, North Carolina State University
Abstract: The increased utilization of satellites by both governments and the private sector will result an increased demand for electronics that can withstand the environment of space. Historically this has led to the use of radiation hardened electronics which are more expensive than standard commercial off the shelf (COTS) components and may be more difficult to obtain, an issue that can be exacerbated by supply chain disruptions. An alternative solution is the addition of metal oxides to conformal coats that are already used to prepare electronics in space. By utilizing NASA standard compliant conformal coating material, critical quality properties are retained sufficient to enable deployment. Modeling of these novel shielding compounds using MCNP6 found that these compounds provide improved shielding worth per mass compared to aluminum for Van Allen Belt electrons as well as a roughly equivalent shielding worth for Van Allen Belt protons.
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TPM-B.2
14:45 Estimation of the Disability-adjusted Life Years attributed by the Occupational Risk in Japan T Kimura*, Central research Institute of Electric Power Industry
; M Sasaki, Central research Institute of Electric Power Industry
Abstract: To set the occupational dose limit, the International Commission on Radiological Protection (ICRP) used the annual occupational mortality rate and the daily normal occupational life in what is usually considered to be a safe society as reference risk levels in the ICRP publications 26 and 60, respectively. Recently, disability-adjusted life years (DALYs) have been discussed as possible alternatives to radiation risk, i.e., radiation detriment, by ICRP. Thus, we have attempted to apply the DALY index to the estimation of occupational risks. DALYs of occupational accidents in Japan were estimated by industry category on the basis of the published insurance records. DALYs from 2002 to 2018 were calculated as the sum of the number of years of life lost (YLLs) and that of years lived with disability (YLDs). In the YLD calculation, the parameters that depended on the classification used, which was different from the Japanese classification, were used. Thus, the classification for the YLD’s parameters need to be corresponded to the Japanese classification. Finally, 77% of the Japanese classification was matched with the classification for the YLD’s parameters. It was found that the occupational risks attributed to the ranges of 1.8–5.0, 3.7–8.6, and 8.0–15.0 DALYs per 1000 workers for all industries, manufacturing, and construction, respectively, in 2018. The estimated DALYs reluctantly have wide range because of the lack of detailed information with regard to diseases and injuries in Japan. The detailed information will be necessary for improving the accuracy of estimated DALYs. The maximum values for all industries, manufacturing, and construction decreased with time. The minimum value for all industries decreased, but those for manufacturing and construction increased up to around 2010 and decreased after 2010. The DALY estimation and its characteristics found in this study will be helpful as a reference risk level when radiation risk is considered inclusively.
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TPM-B.3
15:00 RADIOLOGICAL ASSESSMENT OF QUANTUM SCIENCE PENDENT - A CASE STUDY Omar Y. Al-Somali*, Saudi Aramco
; Omar Y. Al-Somali
Abstract: Scalar energy pendants are widely accessible, and their sellers claim that they enhance the body’s energy flow, restore energy levels, and help maintain health and well-being. This study conducted radiological assessments of six pendants coded as QP1–QP6, including measurement of equivalent dose rates using a portable dose rate meter and software, assessment of the surface contamination, and a wipe test for removable contamination. Skin dose measurements were conducted using thermoluminescence dosimetry, and high-resolution gamma-ray spectrometry analysis was conducted. The committed effective dose (CED) of radionuclides ingested was also calculated based on the International Commission on Radiological Protection’s Publication 119 Compendium of Dose Coefficients, and the activity concentrations from the pendants were compared with the International Atomic Energy Agency (IAEA) SSG-36 report. Sample QP1 demonstrated a maximum external effective dose of 0.3 µSv/h and a contamination level of 91.0 counts per second of contact. The wipe test for removable contamination indicated no reading above the background level for any of the six pendants. Gamma spectroscopy revealed that Uranium-238 and Thorium-232 activity were highest in QP1 at 7.5 and 52.4 Bq/g and lowest in QP2 at 2.3 and 16.5 Bq/g, respectively. The identified specific activities were above the IAEA exemption limit of 1 Bq/g for naturally occurring Uranium-238 and Thorium-232. The CED calculations indicated that ingestion of these samples contributes less than 1.0 mSv/year, which can be viewed as negligible. However, the pendants showed doses several times higher than the IAEA limit of 10 µSv/year for consumer products. In conclusion, scalar energy pendants provide an unnecessary radiation dose to wearers, and regularly wearing these products may be associated with chronic receipt of low-dose-rate radiation. Other studies have recorded high dose rates and activity concentrations for these products. As a result of the current work, we advise that consumers stop wearing these pendants and that these products be banned from circulation to the public.
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TPM-B.4
15:15 Analyzing Culture and Training and Education as Points of Synergy in the Integration of Nuclear Safety and Security in Research Reactors TA Thomas*, Purdue University
; JT Harris, Purdue University
Abstract: As health physicists, radiation protection is one of the primary responsibilities working with a research reactor. The goal is protect workers, the public, and the environment from the potential harm that comes from radiation exposure. Protection is maintained through nuclear safety and security principles. Despite both having the same goal, nuclear safety and security have often been viewed as two conflicting perspectives. To effectively achieve their respective goals of radiation protection, points of integration must be identified and utilized where these two perspectives meet and agree. A previous study analyzed the potential for synergy in a research reactor across eight criteria when integrating nuclear safety and security. The criteria were evaluated using the analytical hierarchy process (AHP)—a multi-tiered method using a pairwise comparison matrix to rate criteria within and across each tier. These results were then used in a Monte Carlo simulation that applied a beta-Program Evaluation Review Technique (PERT) distribution to determine points with the greatest potential for synergy. Culture and education/training were rated as having the greatest potential for synergy, indicating that integration of nuclear safety and security would provide the greatest benefit. Health physicists hold the keys to promoting the synergy of culture and education. Also, annual safety training is one of the requirements that must be maintained for a quality radiation safety program. This study performed a closer analysis of culture and training/education regarding what characteristics in these criteria make them stand out as the criteria with the greatest potential for synergy. The specific components of culture analyzed include policy, leadership, and individual attitudes. The specific components of training/education analyzed are frequency, delivery methods, and trainee receptivity.
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TPM-B.5
15:30 Break
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TPM-B.6
16:00 Development of a Risk Assessment Method for Integrating Nuclear Safety and Security Using Terrorism Scenarios with the PUR-1 Research Reactor J Lee*, Purdue University
; JT Harris, Purdue University
Abstract: Risk assessment is a method for identifying hazards and risk factors that have the potential to be harmful. This method enables assessing risk connected to that hazard, determining the best ways to assess that risk, and then deciding how to manage that risk in cases. Risk assessment should be performed for the entire facility to include both malicious attacks and safety accidents such as those that result in core melting. Although risk assessment is widely used in the fields of nuclear safety and radiation protection, its use in nuclear security has not advanced significantly. Because of this, the Potential Facility Risk Index (PFRI) has been developed to assess the security and safety of nuclear facilities. In this study, nuclear safety probabilistic risk assessment (PRA) techniques were used to analyze the security risk of theft and terrorism in the Purdue University reactor (PUR-1). Results were compared with those calculated by the U.S. Nuclear Regulatory Commission for other nuclear reactors. The security PRA results obtained prove a new method for integration, allowing safety accidents and security incident risks to be compared with one another. As a result, the PFRI will be able to perform integrated risk assessment for safety and security.
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TPM-B.7
16:15 Clarifying Some More Misconceptions about EPA’s Superfund Approach SA Walker*, US Environmental Protection Agency
Abstract: Cleanup levels, for radioactive contamination at U.S. Environmental Protection Agency (EPA) Superfund sites, are generally expressed in terms of risk levels (e.g., 10-4), rather than millirem or millisieverts, as a unit of measure. Although EPA and other US agencies have issued millirem based regulations under other statutory authorities, under Superfund EPA promulgated a risk range of 10-4 to 10-6 as a standard of protectiveness for all carcinogens including radionuclides. Superfund guidance recommends the use of slope factors when estimating cancer risk from radioactive contaminants, rather than dose results in millirem to cancer risk. Current slope factors are based on risk coefficients in Federal Guidance Report 13 (FGR 13). The Superfund remedial program uses 10-6 as a point of departure and establishes Preliminary Remediation Goals (PRGs) at 1 x 10-6. PRGs, not based on other environmental standards known as Applicable or Relevant and Appropriate Requirements (ARARs), are risk-based concentrations, derived from standardized equations combining exposure information assumptions with FGR 13 risk coefficients. The policy rationale and technical underpinnings for this risk management approach, is often misunderstood by radiation professionals. This presentation will help clarify some of these misunderstandings by focusing on misstatements about the Superfund approach that the author has encountered from radiation professionals. Often, they are citing the wrong EPA documents or portions of documents incorrectly, or not reading sections of the correct Superfund guidance. The examples of misconceptions in this 2023 talk will be entirely different than those in my talk at HPS 2021.
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TPM-B.8
16:30 Superfund Update: New and Revised Risk and Dose Assessment Models SA Walker*, US Environmental Protection Agency
Abstract: The EPA Superfund remedial program’s six Preliminary Remediation Goal (PRG) and Dose Compliance Concentration (DCC) internet-based calculators, for risk and dose assessment at Superfund sites, are being revised to reflect better science. The PRG, DCC, and BPRG calculators have a new Peak output option that was issued in 2020, 2022, and 2022, respectively. The Peak BDCC output option is expected to be incorporated into the BDCC calculator prior to HPS 2023, and subsequently the Peak option will be incorporated into the SPRG and SDCC calculators. The Peak option selects a cleanup level based on the time the pure parent and subsequent progeny contribute the most risk or dose. The BPRG and BDCC calculators are expected to have new default dust ingestion parameters to be released by HPS 2023. It is also expected that in 2023 there will be a release of a revision with more choices of building materials and for portions of the room to be considered contaminated when assessing fixed contamination. A new Radon Vapor Intrusion Screening Level (RVISL) calculator was finished in 2021, which is consistent with the Vapor Intrusion Screening Level (VISL) for chemical calculator that was finished in 2018. How the PRG and DCC calculators address radon that is emanating from tap water was adjusted to be consistent with aspects of the RVISL calculator. In 2023, a new Counts Per Minute (CPM) calculator is expected to be released. The CPM calculator will correlate real-time cpm survey results to concentrations that are typically expressed in pCi/g or pCi/m2(i.e., PRGs, DCCs, or environmental data).
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TPM-B.9
16:45 Geographical Data and Methods for estimating Indoor Residential Radon Exposure H Lee*, Georgia Institute of Technology
; GA Agasthya, Oak Ridge National Laboratory; HA Hanson, Oak Ridge National Laboratory; DD Maguire, Oak Ridge National Laboratory; JS Logan, Oak Ridge National Laboratory; AJ Kapadia, Oak Ridge National Laboratory; SA Dewji, Georgia Institute of Technology
Abstract: Traditionally, radon epidemiology has been conducted using retrospective cohorts and occupational or residential exposure. Such residential exposure studies require radon concentration data from the area where the household is located. However, existing published data and widely used radon concentration prediction models are either raw data or data at the large spatial level of counties. These high spatial level data can lead to large errors in analysis with radon concentrations. Gaining stronger estimates of environmental exposure requires exposure modeling at a smaller spatial resolution.
There are large amounts of variation in geographic, building, and meteorological characteristics in regions as large as county-level, and averaging over these spatial extents can lead to errors in exposure estimates at the individual level. In this work, we survey existing methods for estimating environmental exposures at small spatial extents. The surveyed research shows that the use of homogenous and heterogenous ensembling techniques for machine learning (ML) models can lead to more robust estimates. These techniques can also be used to improve the accuracy of estimates at small spatial scales.
This smaller spatial scaled data can be utilized in linking with other data, such as PM 2.5. Although PM2.5 has recently been reported to have a synergistic effect with radon exposure, it also has high spatial variability. If these spatial data can be matched with the small spatial extent, it will allow for the analysis of potential synergistic effects between radon and other exposures.
ML-based ensemble models can predict the radon concentration data in a more granulated manner with higher accuracy when the proper information (e.g., geography, architectural, meteorological data) is provided. Exposure estimates at smaller spatial scales and increased accuracy can be used in future research to guide radon and health-related research.
This work was supported by the Office of Biological and Environmental Research’s, Biological Systems Science Division. This manuscript has been authored by UT-Battelle, LLC under Contract No. DE-AC05-00OR22725 with the U.S. Department of Energy.
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TPM-B.10
17:00 Roles and Responsibilities of the U.S. EPA in Radiological Protection A Ansari*, U.S. Environmental Protection Agency
; S DeCair, U.S. Environmental Protection Agency; J Nagata, U.S. Environmental Protection Agency; D Borrego, U.S. Environmental Protection Agency
Abstract: As authorized by U.S. Congress, the U.S. Environmental Protection Agency (EPA) is responsible for establishing generally applicable standards for the protection of human health and the environment from radioactive materials. In addition to setting legally enforceable standards, EPA issues federal guidance documents with recommendations on radiation protection and technical reports to help standardize methods for dose and risk assessment. Federal guidance recommendations and technical reports are used by federal and state agencies in developing radiation protection regulations and standards. The EPA also has responsibilities in assisting with a national response to nuclear or radiological emergencies. The EPA Radiation Protection Division works to meet this mandate by issuing federal guidance, conducting emergency preparedness and response activities, improving radiological risk communication, and coordination with domestic and international partners. This presentation will provide an overview of the radiological protection mission space of the EPA while pointing out specific examples of regulations, guidance, partnerships, products, and activities that are relevant to the field of health physics.
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TPM-B.11
17:15 The development of an equation to estimate the cost of ALARA during decontamination and decommissioning projects JA Baty*, University of Alabama at Birmingham
; E Caffrey, University of Alabama at Birmingham; C Wilson, University of Alabama at Birmingham; Al Baty
Abstract: The Linear No Threshold hypothesis is a model for estimating carcinogenic risk from doses of ionizing radiation. It assumes that any dose of radiation produces linear risk. This is used for radiation protection purposes and is the basis for radiation regulation in the United Sates and drives the ALARA principle during decontamination and decommissioning projects. There is significant controversy surrounding the use of the LNT model and its applicability, particularly at low doses. While there are many supporters of the LNT model, there are also many health physicists that argue that the use of LNT overestimates carcinogenic risk, particularly at low doses of ionizing radiation. These health physicists advocate for the use of other radiation protection models that use thresholds, below which risk is estimated to be zero. This talk will discuss a financial analysis of the use of the ALARA principle in decommissioning and decontamination projects. The goal is to formulate an equation resulting in an output of dollars/mrem saved, allowing health physicists to further examine the current cost of ALARA principles in decommission and decontamination.
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