Health Phys. Abstracts，Volume 122,Number 5

ImpactoftheCoarseIndoorNon-radioactiveAerosolsontheBackgroundRadonProgenies’CompensationofaContinuousAirMonitor

Gwena⊇l Hoarau1, Grégoire Dougniaux1, François Gensdarmes1, Philippe Cassette2, Gilles Ranchoux3

(1. Institut de Radioprotection et de Sreté Nucléaire (IRSN), PSN-RES, SCA, Laboratoire de physique et mérologie des aérosols (LPMA), Gif-sur-Yvette, 91192. France;2. Commissariat à l'Énergie Atomique et aux Énergies Alternatives (CEA), LIST, Laboratoire National Henri Becquerel (LNE-LNHB), Saclay, 91191, France;3. Élecricité de France (EDF), Direction des Projets Déconstruction-Déchets (DP2D), Lyon, 69006, France)

Abstract:This paper addresses the problem of false positive alarm when using a continuous air monitor (CAM) in decommissioning sites of nuclear facilities. CAMs are used to measure airborne activity and play an important role in the radiation protection of workers likely to be exposed to radioactive aerosols. Monitors usually sample aerosols on a membrane filter. Radioactive particles sampled are detected through the alpha and beta decays that they emit. These latter ionizing particles are measured online by spectrometry thanks to a Passivated Implanted Planar Silicon detector (PIPS). Alpha and beta decays, in this context, come mainly from the natural radon progeny (218Po,214Pb, and so on) and, in the case of radioactive contamination, also from artificial radionuclides such as239Pu or137Cs. The aim of the CAM is to alert the workers when the artificial airborne activity occurs, always considering the presence of a variable background due to the natural particulate airborne activity. The CAM-specific algorithm considers this background dynamically and continuously, often by using a constant parameter. However, non-radioactive aerosols are also sampled on the membrane filter. These latter make the discrimination more difficult as they lead to the deterioration of the alpha-energy spectrum. In this paper, the effect of coarse non-radioactive aerosols on the CAM response is highlighted with four aerosol size-distributions. The evolution of the background is characterized as a function of the aerosol mass sampled, with the example of a simple algorithm. Thus, in this paper, results show a positive correlation of the background with the aerosol mass sampled by the CAM. In addition, results highlight at least two different evolutionary trends according to the aerosol size distribution. An explanation of these evolutions is given by considering the penetration profile of the natural radioactive aerosols in the granular deposit above the CAM filter. The main consequence of these results is that the background could not be considered as proportional to radon progeny as it is currently used.

Keywords: aerosols; monitors; radiation; nuclear power plant; radiation; background

Health Phys. 122(5):563-574; 2022

Radon-222BrainDosimetry

Naomi H. Harley1, Edith S. Robbins2

(1.Naomi H. Harley, New York University School of Medicine, Department of Environmental Medicine, 1. Marine View Plaza, Apt. 24E, Hoboken, NJ 07030;2.Edith S. Robbins, New York University School of Medicine, Department of Cell Biology, easr@optonline.net (retired).)

Abstract:The human brain dose from radon-222 (222Rn) exposure is calculated here using222Rn tissue solubility data. A fraction of222Rn inhaled dissolves in blood and cellular fluids and circulates to brain and all organs. Radon-222 has a relatively high solubility in blood and body fluids based on human inhalation experiments. The brain dose uses calculated concentrations of222Rn in blood and cellular fluids from exhaled breath measurements following human exposure in a222Rn chamber. The annual brain dose from continuous inhalation of a concentration of 100 Bq m-3is about 450 times less than the dose to bronchial epithelium from inhalation of the same222Rn concentration. Based on the222Rn dosimetry here, it is highly unlikely that brain cancer is related to even high222Rn exposures. Any functional or neurodegenerative issues from exposure to very small doses of222Rn alpha particles are, at present, unknown.

Keywords:222Rn; cancer; dose assessment; inhalation

Health Phys. 122(5):575-578; 2022

ComparativeStudyofRadiation-inducedLungInjuryModelinTwoStrainsofMice

Shiying Niu, Yuehua Zhang, Changsheng Cong, Zhicheng Wu, Zhaopeng Wang, Meili Sun, Chengfang Yao, Yueying Zhang1

(1.Shandong First Medical University, College of Basic Medicine, Shandong First Medical University-Shandong Academy of Medical Sciences, Jinan, Shandong, 250000, China)

Abstract:Radiation-induced lung injury (RILI) is a common complication of radiotherapy for thoracic tumor. Its incidence rate is as high as 20%. At present, there is no effective treatment in clinical practice. However, to study the mechanism of radiation-induced lung injury, we should first establish an appropriate animal model. In a series of scientific studies on RILI, mice are the animals most often chosen by researchers. However, there are few reports on which strain of mice is more suitable as a model of RILI. In this study, Kunming (KM) and C57BL/6 strains of mice were used as research objects to find the most suitable mice to replicate the RILI model. C57BL/6 mice and KM mice were exposed to irradiation at a dose of 20 Gy. The lung tissue of C57BL/6 mice exposed to radiation showed dilation and hyperemia of capillaries, infiltration of inflammatory cells, and thickening of alveolar septum, while the lung tissue of KM mice exposed to radiation was not as obvious as that of C57BL/6 mice. After irradiation, the expression of interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) in the lung tissue of C57BL/6 mice was significantly increased, while the expression of IL-6 and TNF-α in KM mice was almost unchanged. These studies showed that C57BL/6 mice are more suitable for the model of radiation-induced lung injury because of sensitive inflammatory reaction and the pathological changes of lung tissue.

Keywords: health effects; lungs; rodent; medical radiation; radiation therapy

Health Phys. 122(5):579-585; 2022

DischargesofNuclearMedicineRadioisotopes:TheImpactofanAbatementSystem

Nathaly Barbosa1, Lorena Sandoval Castillo1, Juan Sebastián Quimbayo1

(1.Instituto Nacional de Cancerología, Calle 1 # 9-85, Bogotá, Colombia)

Abstract:Clinical uses of radiopharmaceuticals imply the administration of radioactive substances that are mainly excreted through urine. The Nuclear Medicine Department at the Instituto Nacional de Cancerología (INC-COL) in Bogota, Colombia, administers radiopharmaceuticals for diagnostics and treatment to many patients, resulting in tens of cubic meters of radioactive waste water (WW) every day. As Colombian regulatory limits for liquid radioactive discharges to the sewer system are lower than in other countries, longer WW decay times are required, even when an in-house waste water treatment plant (WWTP) is used. To fulfill the requirements for controlled disposal of radioactive discharges, a complementary abatement system was implemented to retain WW for periods as long as 360 d, and was connected to the hospital’s WWTP. These holding times can cause major changes in the WW physicochemical parameters, reaching levels higher than acceptable. In this study, we evaluate the decontamination and decay efficiency of the retention system using water quality parameters and the amount of radioactivity in the effluents stored in the tanks and the WWTP. According to the results, to maintain the physicochemical parameters below acceptable levels, biological and chemical treatment of decayed WW is necessary before discharging it into urban waste water. Using the principles of dilution, retention, and decay, an integral radioactive WW management system was implemented favoring the quality of discharges and activity levels to the sewer system, with efficiencies close to 100% for WW from discharges in diagnostic procedures ranging from 98% (131I) to 100% (177Lu) for WW from discharges in therapeutic procedures. Activity concentration assessment in medically-derived radionuclides using an in-house waste water treatment plant (WWTP) and a complementary abatement system; an in-house WWTP could be used as an abatement system for short-lived radionuclides; and a tank-based abatement system attached to the in-house WWTP showed higher efficiencies for long-lived radionuclides and adequate physicochemical parameters for the discharge to the city sewage system.

Keywords: nuclear medicine; wastewater;131I; activity concentration; abatement system; decay

Health Phys. 122(5):586-593; 2022

TheDevelopmentandApplicationofaQuasi-dynamicFoodChainModelinChineseAgriculturalConditions

Huiling Cui, Rentai Yao, Junfang Zhang, Sha Huang, Minghua Lv, Duoxing Zhao, Qiang Wu1

(1.China Institute of Radiation Protection, Taiyuan 030006, China)

Abstract:A quasi-dynamic food chain model (Chi-FDMT) was developed to predict the consequences of nuclear accidents on the food chain through the ingestion pathway in Chinese agricultural conditions. The Chi-FDMT structure is based on ECOSYS-87, with some revised calculation processes and the adoption of new parameters; herein, it was applied to two regions in China. The model was used to estimate the spatial and temporal patterns of crop plant activity and ingestion dose in the Chinese agricultural environment at the scale of the Fukushima nuclear disaster. A comparative study between Chi-FDMT and an equilibrium model demonstrated good agreement for depositions occurring during the growth season. The parameter sensitivity analysis of Chi-FDMT indicated that the parameters of food intake and processing factor are sensitive, and the sensitivity of the transfer factors within plant and soil-plant systems are dependent on the deposition scenario.

Keywords: accidents; nuclear; food chain; nutrition pathways; transport; environmental

Health Phys. 122(5):594-606; 2022

Why“Measurand”IstheFirstScientificWordWeShouldTeachHealthPhysicists

Daniel J. Strom1, George Tabatadze1

(1.US Transuranium and Uranium Registries, College of Pharmacy and Pharmaceutical Sciences, Washington State University, 1845 Terminal Drive, Suite 201, Richland, WA 99354-4959)

Abstract:The word “measurand” means “the quantity intended to be measured”. The authors argue that health physicists should distinguish between measurands and measurement results because the former exist in the domain of theory, while the latter exist in the domain of reality in which we make measurements and observations. The authors demonstrate the importance of separating the quantities used in theory and those used in experiment, clearing up conceptual confusions in three examples of problems routinely encountered in health physics: (1) detection and quantification of radioactive material; (2) multiple definitions of “activity”, and (3) the relationship between radiation and health effects. The first example looks into probabilities of various measurement results (mi) given the measurand (μ) in comparison with the inverse problem: determining probable values of the measurand (μ) based on observed measurement results (mi). The second example addresses the distinction between measurands and measurement results given two definitions of activityAprovided by the International Commission on Radiation Units and Measurements. Additional consideration is given to use ofN+1 counts in (activity) calculations when we have observedNcounts, which results from correctly stating and solving the inverse problem. This makes our measurement uncertainties more accurate and our detection decisions more reliable. The last example emphasizes how the observational results of epidemiology, animal experiments, and other radiation biology studies are used to estimate the probability of a particular cancer in an individual—a measurand that is not otherwise accessible to direct observation. Our measurement results, and our use of those results, are more easily understood when we understand the difference between a measurand and a measurement result and can choose the best calculational approach.

Keywords: detection limits; health effects; minimum detectable activity; statistics

Health Phys. 122(5):607-613; 2022

DiscoveryofThirdPossibleIonGeneratingSourcein4πPlasmaFocusDeviceSpace

Mehdi Sohrabi1

(1.Health Physics and Dosimetry Research Laboratory Department of Energy Engineering and Physics, Amirkabir University of Technology, P.O. Box 159163-4311, Tehran, Iran)

Abstract:Discovery of a possible third source of ion generation in 4π Plasma Focus Device (PFD) space is reported. Unexpected observation of dense ion tracks, called “On Shadow Ion Tracks” (OSIT), on the “ion cathode shadows” (ICS) was discovered. These ions were formed on panorama mega-size cylindrical polycarbonate ion image detectors placed behind the cathodes in the PFD space on PFD wall, where no ion tracks are expected to exist. Such unexpected ion tracks were observed when different gases were used, in particular hydrogen, deuterium, and helium. An ICS is formed on the detector when each cathode shadows and removes all ions bombarding it from the “anode top” and “anode cathodes assembly”. Such ion tracks forming the OSITs seem to be generated not from the “anode top” and “a node cathodes assembly” but also from a third possible ion source in PFD space bombarding the detector.

Keywords: plasma focus device; discovery; polycarbonate detector; ion generation

Health Phys. 122(5):614-617; 2022

RadiologicalHEPAFilter10-yearLifetimeEvaluationinResearchFacilities

J. Matthew Barnett1, Mary Bliss1, Kobe R. Schrank1,2, Hunter Z. Edwards1, David M. Brown1,3, Kent M. McDonald1, Scott K. Cooley1

(1.Pacific Northwest National Laboratory, PO Box 999, MSIN J2-25, Richland, WA 99352;2. Presently at Packaging Corporation of America, 31831 West Highway 12, Wallula, WA 99363;3. Retired, 6450 24th Ave NW, Apt 527, Seattle, WA 98107)

Abstract:High-efficiency particulate air (HEPA) filters are widely employed by nuclear facilities to remove radiological particulate matter from their effluent exhaust streams. The purpose of this study is to evaluate the relationships between the 10-y HEPA filter lifetime deployment and its other performance indicators. This 10-y-long endeavor to collect and analyze data regarding the service life of HEPA filters at the Pacific Northwest National Laboratory began in 2010. A set of HEPA filters was selected, and the filters have been surveyed and analyzed at least annually to verify compliance with permit conditions. The study suggests the frequency of filter replacement should be based on the actual operational requirements, such as fume hood face velocity and/or efficiency test results, instead of on the prescribed filter “age limit” of 10 y from the date of manufacture (e.g., birth date) when operating under dry conditions. The study has now been completed, and over the past decade, all the HEPA filters have been replaced due to either technical issues as listed in this report or the previously recommended filter “age limit” of 10 y as prescribed by the oversight bodies. Experimentally determined failure rates are also determined from the data set and can be used to estimate the chances of HEPA filters surviving 15, 20, or even 30 y.

Keywords: HEPA filter; airborne emissions; lifetime; regulatory compliance; standards and guidelines

Health Phys. 122(5):618-624; 2022

ADescriptionofICNIRP’SIndependent,BestPracticeSystemofGuidanceontheProtectionofPeopleandtheEnvironmentfromExposuretoNon-IonizingRadiation

(International Commission on Non-Ionizing Radiation Protection (ICNIRP)The International Commission on Non-Ionizing Radiation Protection (ICNIRP) collaborators are listed in the Acknowledgement section))

Abstract:In this statement, the International Commission on Non-Ionizing Radiation Protection (ICNIRP) presents its structure, its activities, and general approach to providing guidance on NIR protection. The statement highlights ICNIRP’s independence and presents the principle and requirements of no commercial or other vested interests. ICNIRP’s funding arrangements and collaboration with other advisory bodies and radiation protection authorities are also described. The statement also presents the types of guidance documents that are produced by ICNIRP and the general approach in assessing scientific evidence.

Keywords: International Commission on Non-Ionizing Radiation Protection (ICNIRP); radiation; non-ionizing; radiation safety; safety standards

Health Phys. 122(5):625-628; 2022

QuantificationofaFacilityRadiologicalSecurityRiskIndexWithaGraphicalUserInterfaceTool

Shraddha Rane, Jason T. Harris1

(1.School of Health Sciences, Purdue University, 550 Stadium Mall Drive, West Lafayette, IN 47907)

Abstract:Healthcare facilities around the world routinely use radioactive sources to diagnose and treat illness. To effectively manage the security of radioactive sources, these facilities need to understand the risk, which is comprised of threat, vulnerability, and consequences. The threat component of risk requires knowledge of potential adversaries and understanding their capabilities and intentions. To help articulate the multiple layers of threat and support better informed decisions, the research developed a risk-based methodology to evaluate radiological security at the facility level. The methodology is applied to a radiological dispersal device (RDD) incident from three radionuclides of concern:137Cs,60Co, and192Ir. The results of the research have led to the creation of a potential facility risk index (PFRI). The PFRI is mathematically represented as the exponential product of the maximum expected utility among the threat groups, the sum of geographic vulnerability and cultural vulnerability, and net consequences. The PFRI is a novel risk index that quantifies the facility risk on a scale of 1 to 10, 1 being “very low risk” and 10 being “very high risk”. A MATLAB-based graphical user interface (GUI) tool was also developed to enable the radiological facility (i.e., healthcare facility) staff to conduct self-assessments and manage their most valuable assets. The PFRI methodology is a useful starting point for any healthcare facility risk assessment and is a valuable input for decision makers considering potential investments in security upgrades.

Keywords: operational topics;137Cs; emergencies; radiological; radiation risk

Health Phys. 122(5):632-644; 2022