G. Timothy Jannik

Chronic irradiation of Scots pine trees (Pinus sylvestris) in the Chernobyl exclusion zone: dosimetry and radiobiological effects.

To identify effects of chronic internal and external radiation exposure for components of terrestrial ecosystems, a comprehensive study of Scots pine trees in the Chernobyl Exclusion Zone was performed. The experimental plan included over 1,100 young trees (up to 20 y old) selected from areas with varying levels of radioactive contamination. These pine trees were planted after the 1986 Chernobyl Nuclear Power Plant accident mainly to prevent radionuclide resuspension and soil erosion. For each tree, the major morphological parameters and radioactive contamination values were identified. Cytological analyses were performed for selected trees representing all dose rate ranges. A specially developed dosimetric model capable of taking into account radiation from the incorporated radionuclides in the trees was developed for the apical meristem. The calculated dose rates for the trees in the study varied within three orders of magnitude, from close to background values in the control area (about 5 mGy y−1) to approximately 7 Gy y−1 in the Red Forest area located in the immediate vicinity of the Chernobyl Nuclear Power Plant site. Dose rate/effect relationships for morphological changes and cytogenetic defects were identified, and correlations for radiation effects occurring on the morphological and cellular level were established.

RADIATION ECOLOGY ISSUES ASSOCIATED WITH MURINE RODENTS AND SHREWS IN THE CHERNOBYL EXCLUSION ZONE

This article describes major studies performed by the Chernobyl Centers International Radioecology Laboratory (Slavutich, Ukraine) on radioecology of murine rodents and shrews inhabiting the Chernobyl Exclusion Zone. The article addresses the long-term (1986–2005) and seasonal dynamics of radioactive contamination of animals and reviews interspecies differences in radionuclide accumulations and factors affecting the radionuclide accumulations. It is shown that bioavailability of radionuclides in the “soil-to-plant” chain and a trophic specialization of animals play key roles in determining their actual contamination levels. The total absorbed dose rates in small mammals significantly reduced during the years following the Chernobyl Nuclear Power Plant accident. In 1986, the absorbed dose rate reached 1.3–6.0 Gy h−1 in the central areas of the Chernobyl Exclusion Zone (the “Red Forest”). In 1988 and 1990, the total absorbed dose rates were 1.3 and 0.42 Gy h−1, respectively. In 1995, 2000, and 2005, according to the present study, the total absorbed dose rates rarely exceeded 0.00023, 0.00018, and 0.00015 Gy h−1, respectively. Contributions of individual radiation sources into the total absorbed dose are described.

RadBall™ Technology Testing in the Savannah River Site’s Health Physics Instrument Calibration Laboratory

The United Kingdoms National Nuclear Laboratory (NNL) has developed a radiation-mapping device that can locate and quantify radioactive hazards within contaminated areas of the nuclear industry. The device, known as RadBall(™), consists of a colander-like outer collimator that houses a radiation-sensitive polymer sphere. The collimator has over two hundred small holes; thus, specific areas of the polymer sphere are exposed to radiation becoming increasingly more opaque in proportion to the absorbed dose. The polymer sphere is imaged in an optical-CT scanner that produces a high resolution 3D map of optical attenuation coefficients. Subsequent analysis of the optical attenuation data provides information on the spatial distribution of sources in a given area forming a 3D characterization of the area of interest. The RadBall(™) technology has been deployed in a number of technology trials in nuclear waste reprocessing plants at Sellafield in the United Kingdom and facilities of the Savannah River National Laboratory (SRNL). This paper summarizes the tests completed at SRNL Health Physics Instrument Calibration Laboratory (HPICL).

RadBall™ Technology Testing and MCNP Modeling of the Tungsten Collimator

The United Kingdoms National Nuclear Laboratory (NNL) has developed a remote, non-electrical, radiation-mapping device known as RadBall(™), which can locate and quantify radioactive hazards within contaminated areas of the nuclear industry. RadBall(™) consists of a colander-like outer shell that houses a radiation-sensitive polymer sphere. The outer shell works to collimate radiation sources and those areas of the polymer sphere that are exposed react, becoming increasingly more opaque, in proportion to the absorbed dose. The polymer sphere is imaged in an optical-CT scanner, which produces a high resolution 3D map of optical attenuation coefficients. Subsequent analysis of the optical attenuation matrix provides information on the spatial distribution of sources in a given area forming a 3D characterization of the area of interest. RadBall(™) has no power requirements and can be positioned in tight or hard-to reach locations. The RadBall(™) technology has been deployed in a number of technology trials in nuclear waste reprocessing plants at Sellafield in the United Kingdom and facilities of the Savannah River National Laboratory (SRNL). This study focuses on the RadBall(™) testing and modeling accomplished at SRNL.

An Overview of 137Cs Contamination in a Southeastern Swamp Environment.

In the early 1960’s, an area of privately owned swamp adjacent to the Savannah River Site was contaminated by site operations. Studies conducted in 1974 estimated that approximately 925 GBq of 137Cs and 37 GBq of 60Co were deposited in the swamp. Subsequently, a series of surveys was initiated to characterize the contaminated environment. These surveys—composed of 52 monitoring locations—allow for continued monitoring at a consistent set of locations. Initial survey results indicated maximum 137Cs concentrations of 19.5 Bq g−1 in soil and 8.7 Bq g−1 in vegetation. By the 2004–2005 surveys, maximum concentrations had declined to 1–2 Bq g−1 in soil and 0.4 Bq g−1 in vegetation.

Site-specific reference person parameters and derived concentration standards for the Savannah River Site.

AbstractThe U.S. Department of Energy Order 458.1 states that the compliance with the 1 mSv annual dose constraint to a member of the public may be demonstrated by calculating dose to the maximally exposed individual (MEI) or to a representative person. Historically, the MEI concept was used for dose compliance at the Savannah River Site (SRS) using adult dose coefficients and adult male usage parameters. For future compliance, SRS plans to use the representative person concept for dose estimates to members of the public. The representative person dose will be based on the reference person dose coefficients from the U.S. DOE Derived Concentration Technical Standard and on usage parameters specific to SRS for the reference and typical person. Usage parameters and dose coefficients were determined for inhalation, ingestion and external exposure pathways. The reference intake for air, water, meat, dairy, freshwater fish, saltwater invertebrates, produce (fruits and vegetables), and grains for the 95th percentile are 17.4 m3 d−1, 2.19 L d−1, 220.6 g d−1, 674 cm3 d−1, 66.4 g d−1, 23.0 g d−1, 633.4 g d−1 (448.5 g d−1and 631.7 g d−1) and 251.3 g d−1, respectively. For the 50th percentile: 13.4 m3 d−1, 0.809 L d−1, 86.4 g d−1, 187 cm3 d−1, 8.97 g d−1, 3.04 g d−1, 169.5 g d−1 (45.9 g d−1 and 145.6 g d−1), 101.3 g d−1, respectively. These parameters for the representative person were used to calculate and tabulate SRS-specific derived concentration standards (DCSs) for the pathways not included in DOE-STD‐1196‐2011.

Radioactive waste management in the Chernobyl exclusion zone: 25 years since the Chernobyl nuclear power plant accident.

Radioactive waste management is an important component of the Chernobyl Nuclear Power Plant accident mitigation and remediation activities in the so-called Chernobyl Exclusion Zone. This article describes the localization and characteristics of the radioactive waste present in the Chernobyl Exclusion Zone and summarizes the pathways and strategy for handling the radioactive waste-related problems in Ukraine and the Chernobyl Exclusion Zone and, in particular, the pathways and strategies stipulated by the National Radioactive Waste Management Program.

RISK-BASED RADIOACTIVE LIQUID EFFLUENT MONITORING REQUIREMENTS AT THE U.S. DEPARTMENT OF ENERGY'S SAVANNAH RIVER SITE

For Department of Energy (DOE) facilities, clear regulatory guidance exists for structuring radiological air emissions monitoring programs. However, there are no parallel regulations for radiological liquid effluent monitoring programs. In order to bridge this gap and to technically justify liquid effluent monitoring decisions at DOEs Savannah River Site, a graded, risk-based approach has been established to determine the monitoring and sampling criteria to be applied at each liquid discharge point.

Dose Comparisons for a Site-specific Representative Person Using the Age-dependent Dose Coefficients in Cap88-pc Version 4.

Abstract Most U.S. Department of Energy (DOE) facilities with radiological airborne releases use the U.S. Environmental Protection Agency’s (EPA) environmental dosimetry code CAP88‐PC to demonstrate compliance with regulations in 40CFR61, subpart H [National Emission Standards for Hazardous Air Pollutants: Radiological (NESHAP)]. In 2015, EPA released Version 4 of CAP88‐PC, which included significant modifications that improved usability and age-dependent dose coefficients and usage factors for six age groups (infant, 1 y, 5 y, 10 y, 15 y, and adult). However, EPA has not yet provided specific guidance on how to use these age-dependent factors. For demonstrating compliance with DOE public dose regulations, the Savannah River Site (SRS) recently changed from using the maximally exposed individual (MEI) concept (adult male) to the representative person concept (age- and gender-averaged reference person). In this study, dose comparisons are provided between the MEI and a SRS-specific representative person using the age-specific dose coefficients and usage factors in CAP88‐PC V.4. Dose comparisons also are provided for each of the six age groups using five radionuclides of interest at SRS (tritium oxide, 137Cs, 90Sr, 239Pu, and 129I). In general, the total effective dose increases about 11% for the representative person as compared to the current NESHAP MEI because of the inclusion of the more radiosensitive age groups.

OVERVIEW OF THE COOPERATION BETWEEN THE CHERNOBYL CENTERʼS INTERNATIONAL RADIOECOLOGY LABORATORY IN SLAVUTYCH, UKRAINE, AND U.S. RESEARCH CENTERS BETWEEN 2000 AND 2010

The International Radioecology Laboratory (IRL) located in Slavutych, Ukraine, was created in 1999 under the initiative of the United States Government and the Government of Ukraine in the framework of international cooperation on evaluation and minimization of consequences of the Chernobyl nuclear power plant (ChNPP) accident. Since the time the IRL was founded, it has participated in a large number of projects, including the following: 1) study of radionuclide accumulation, distribution, and migration in components of various ecological systems of the Chernobyl Exclusion Zone (ChEZ); 2) radiation dose assessments; 3) study of the effects of radiation influence on biological systems; 4) expert analysis of isotopic and quantitative composition of radioactive contaminants; 5) development of new methods and technologies intended for radioecological research; 6) evaluation of future developments and pathways for potential remediation of the ChEZ areas; 7) assistance in provision of physical protection systems for ionizing irradiation sources at Ukrainian enterprises; 8) reviews of open Russian language publications on issues associated with consequences of the ChNPP accident, radioactive waste management, radioecological monitoring, and ChNPP decommissioning; 9) conduct of training courses on problems of radioecology, radiation safety, radioecological characterization of test sites and environmental media, and research methods; 10) conduct of on-site scientific conferences and workshops on the ChEZ and radioecology problems; participation in off-site scientific conferences and meetings; and 11) preparation of scientific and popular science publications and interactions with mass media representatives. This article provides a brief overview of the major achievements resulting from this cooperation between the IRL and U.S. research centers.