3D Covalent Organic Framework with "the" Topology.

Discovery of new topology covalent organic frameworks (COFs) is a mainstay in reticular chemistry and materials research because it not only serves as a stepwise guide to the designed construction of covalent-organic architectures but also helps to comprehend function from structural design point-of-view. Proceeding on this track, the first 3D COF, TUS-38, with the topology is constructed by reticulating a planar triangular 3-c node of D3h symmetry with a tetragonal prism 8-c node of D2h symmetry via [3 + 8] reversible imine condensation reaction. TUS-38 represents a twofold interpenetrated multidirectional pore network with a high degree of crystallinity and structural integrity. Interestingly, stemming from the nitrogen-rich s-triazine rings with electron-deficient character and ─C â• N─ linkages composing the TUS-38 framework that benefit to the charge-transfer and hence dipole-dipole electrostatic interactions between the framework and iodine in addition to exclusive topological characteristics of the exotic the net, TUS-38 achieves an exemplary capacity for iodine vapor uptake reaching 6.3 g g-1. Recyclability studies evidence that TUS-38 can be reused at least five times retaining 95% of its initial adsorption capacity; while density functional theory (DFT) calculations have heightened the understanding of the interactions between iodine molecules and the framework.

Disentangling the History of Deep Ocean Disposal for DDT and Other Industrial Waste Off Southern California.

Ocean disposal of industrial waste from technical DDT [mainly 1,1'-(2,2,2-trichloroethane-1,1-diyl)bis(4-chlorobenzene), or 4,4'-DDT] manufacture occurred historically in the Southern California Bight. However, the paucity of historical records highlights uncertainties as to the mode, location, and timing of disposal or ongoing ecological effects of these wastes. This study combines sampling, chemical analysis, and numerical modeling of deep San Pedro Basin sediments revealing substantial DDT contamination that extends at least 25 km from the mainland. These findings narrate bulk DDT waste disposal to the offshore that peaked in the 1950s, prior to the onset of formal regulations; was agnostic to later-designated disposal sites; and has experienced sluggish transformation. Our findings further indicate an attenuating secondary source for the DDT daughter product, 1-chloro-4-[2,2-dichloro-1-(4-chlorophenyl)ethenyl]benzene (4,4'-DDE), which still deposits into deep San Pedro Basin sediments. While demonstrating the severity of DDT contamination to the region, these findings further define the burial potential of DDT wastes and inform the past, present, and future contamination potential that is needed to understand and predict ecological consequences. This work also points firmly to bulk, not containerized, disposal of DDT waste and to potential alternative contents of collocated waste.

(Re)integrating radioactive materials and waste into a global sustainable development context.

The 17 Sustainable Development Goals (SDGs) of the United Nations, established in 2015, aim to achieve global sustainability by 2030 through the improvement of environmental, social, and economic parameters. However, unlike earlier concepts such as the Agenda 21 of 1992, the SDGs overlook radioactive waste management and related challenges of radiation itself. First, we investigate the historic consideration and unexplained disappearance of radioactive waste in earlier sustainability concepts. Then, we propose amending seven SDGs to address this gap. For SDGs 6 (Clean Water and Sanitation), 14 (Life Below Water), and 15 (Life on Land), new or revised indicators should monitor the release of hazardous materials. SDGs 9 (Industry, Innovation and Infrastructure), 16 (Peace, Justice and Strong Institutions), and 17 (Partnerships for the Goals) require additional targets and indicators to integrate international cooperation and social implications of nuclear facilities' operation. Redefining "hazardous waste" in SDG 12 (Responsible Consumption and Production) and "environmentally sound technologies" in SDG 17 is necessary to encompass radioactive waste. Implementing these changes demands statistical efforts, but the existing monitoring infrastructure, particularly in Europe and North America, can facilitate this. As 2030 approaches, it is crucial to reintroduce radioactive waste management into sustainability agendas, whether within the SDGs themselves or in a subsequent framework.

Putting radioactive materials on the sustainability agenda: a report from a workshop on the sustainability of human-made radioactive materials held at the safeND Research Symposium 2023.

This report summarizes the findings of a workshop held at the safeND Research Symposium and hosted by the German Federal Office for the Safety of Radioactive Waste Management (BASE) in Berlin in September 2023. The workshop aimed to channel perspectives from various fields of expertise to discuss key sustainability concepts in terms of radioactive waste management. Therefore, the report highlights that current sustainability concepts, such as the United Nations' Sustainable Development Goals (SDG) as well as the concept of Planetary Boundaries, neglect challenges arising from the production and storage of human-made radioactive materials. The workshop consisted of three group tasks. The first attempted at identifying the interrelations between "sustainability" and radioactive waste management. The second was to map the global nature of the challenges. The third took first steps to determine a human-made radioactive material as a potential planetary sub-boundary for "novel entities". All three groups identified valuable knowledge gaps that should be addressed by future research and concluded that radioactive waste management is underrepresented in these sustainability concepts.

Scenario development for safety assessment in deep geologic disposal of high-level radioactive waste and spent nuclear fuel: A review.

Radiation and radioactive substances result in the production of radioactive wastes which require safe management and disposal to avoid risks to human health and the environment. To ensure permanent safe disposal, the performance of a deep geological repository for radioactive waste is assessed against internationally agreed risk-based standards. Assessing postclosure safety of the future system's evolution includes screening of features, events, and processes (FEPs) relevant to the situation, their subsequent development into scenarios, and finally the development and execution of safety assessment (SA) models. Global FEP catalogs describe important natural and man-made repository system features and identify events and processes that may affect these features into the future. By combining FEPs, many of which are uncertain, different possible future system evolution scenarios are derived. Repository licensing should consider both the reference or "base" evolution as well as alternative futures that may lead to radiation release, pollution, or exposures. Scenarios are used to derive and consider both base and alternative evolutions, often through production of scenario-specific SA models and the recombination of their results into an assessment of the risk of harm. While the FEP-based scenario development process outlined here has evolved somewhat since its development in the 1980s, the fundamental ideas remain unchanged. A spectrum of common approaches is given here (e.g., bottom-up vs. top-down scenario development, probabilistic vs. bounding handling of uncertainty), related to how individual numerical models for possible futures are converted into a determination as to whether the system is safe (i.e., how aleatoric uncertainty and scenarios are integrated through bounding or Monte Carlo approaches).

Hybrid Twins Modeling of a High-Level Radioactive Waste Cell Demonstrator for Long-Term Temperature Monitoring and Forecasting.

Monitoring a deep geological repository for radioactive waste during the operational phases relies on a combination of fit-for-purpose numerical simulations and online sensor measurements, both producing complementary massive data, which can then be compared to predict reliable and integrated information (e.g., in a digital twin) reflecting the actual physical evolution of the installation over the long term (i.e., a century), the ultimate objective being to assess that the repository components/processes are effectively following the expected trajectory towards the closure phase. Data prediction involves using historical data and statistical methods to forecast future outcomes, but it faces challenges such as data quality issues, the complexity of real-world data, and the difficulty in balancing model complexity. Feature selection, overfitting, and the interpretability of complex models further contribute to the complexity. Data reconciliation involves aligning model with in situ data, but a major challenge is to create models capturing all the complexity of the real world, encompassing dynamic variables, as well as the residual and complex near-field effects on measurements (e.g., sensors coupling). This difficulty can result in residual discrepancies between simulated and real data, highlighting the challenge of accurately estimating real-world intricacies within predictive models during the reconciliation process. The paper delves into these challenges for complex and instrumented systems (multi-scale, multi-physics, and multi-media), discussing practical applications of machine and deep learning methods in the case study of thermal loading monitoring of a high-level waste (HLW) cell demonstrator (called ALC1605) implemented at Andra's underground research laboratory.

Radiological safety assessment for transportation of reactor pressure vessel during decommissioning of a nuclear power plant in Korea.

In Korea, decommissioning of nuclear power plants and transportation of the decommissioning waste are expected to expand in the near future. It is necessary to confirm that radiological risks to the public and workers are not significant through radiological safety assessment. The objective of this study is to assess the radiological safety for transportation of RPV waste, which is a major decommissioning waste with relatively high level of radioactivity. It was assumed that the waste would be transported to the Gyeongju disposal facility by land transportation. First, the source term and transportation method of the RPV waste were determined, and the external dose rates from the waste were calculated using MCNP. Then, transportation scenarios were assumed under both normal and accident conditions. Under the scenarios, radiation doses were calculated using the RADTRAN. Under normal operation scenarios without a transportation accident, assuming 40 shipments per year, the average individual doses for the public ranged from 6.56×10-6to 2.18×10-2mSv yr-1. The maximum individual doses for only a single shipment ranged from 2.43×10-6to 3.14×10-1mSv. For cargo handlers and vehicle crew members, the average doses were 2.26×101mSv yr-1and 2.95 mSv yr-1, respectively. Under transportation accident scenarios, average individual radiological risks which are product of the radiation doses and the annual accident rates ranged from 1.14×10-11to 1.61×10-10mSv yr-1by transportation route segment when considering the transportation accident rate. Average individual doses assuming transportation accident occurrence ranged from 2.62×10-4to 1.42×10-3mSv. The maximum individual dose under accident conditions was 7.99×10-2mSv. The calculated doses were below the regulatory limits in Korea. However, relatively high doses were observed for cargo handlers and vehicle crew members because of conservative assumptions. This study results can be used as basic data for the radiological safety assessment for the decommissioning waste transportation in the future.

Dramatic loss of microbial viability in bentonite exposed to heat and gamma radiation: implications for deep geological repository.

Bentonite is an integral part of the engineered barrier system (EBS) in deep geological repositories (DGR) for nuclear waste, but its indigenous microorganisms may jeopardize long-term EBS integrity. To predict microbial activity in DGRs, it is essential to understand microbial reactions to the early hot phase of DGR evolution. Two bentonites (BCV and MX-80) with varied bentonite/water ratios and saturation levels (compacted to 1600 kg.m- 3 dry density/powder/suspension), were subjected to heat (90-150 °C) and irradiation (0.4 Gy.h- 1) in the long-term experiments (up to 18 months). Molecular-genetic, microscopic, and cultivation-based techniques assessed microbial survivability. Exposure to 90 °C and 150 °C notably diminished microbial viability, irrespective of bentonite form, with negligible impacts from irradiation or sample type compared to temperature. Bentonite powder samples exhibited microbial recovery after 90 °C heating for up to 6 months but not 12 months in most cases; exposure to 150 °C had an even stronger effect. Further long-term experiments at additional temperatures combined with the mathematical prediction of temperature evolution in DGR are recommended to validate the possible evolution and spatial distribution of microbially depleted zones in bentonite buffer around the waste canisters and refine predictions of microbial effects over time in the DGR.

Extremophilic microbial metabolism and radioactive waste disposal.

Decades of nuclear activities have left a legacy of hazardous radioactive waste, which must be isolated from the biosphere for over 100,000 years. The preferred option for safe waste disposal is a deep subsurface geological disposal facility (GDF). Due to the very long geological timescales required, and the complexity of materials to be disposed of (including a wide range of nutrients and electron donors/acceptors) microbial activity will likely play a pivotal role in the safe operation of these mega-facilities. A GDF environment provides many metabolic challenges to microbes that may inhabit the facility, including high temperature, pressure, radiation, alkalinity, and salinity, depending on the specific disposal concept employed. However, as our understanding of the boundaries of life is continuously challenged and expanded by the discovery of novel extremophiles in Earth's most inhospitable environments, it is becoming clear that microorganisms must be considered in GDF safety cases to ensure accurate predictions of long-term performance. This review explores extremophilic adaptations and how this knowledge can be applied to challenge our current assumptions on microbial activity in GDF environments. We conclude that regardless of concept, a GDF will consist of multiple extremes and it is of high importance to understand the limits of polyextremophiles under realistic environmental conditions.

Mechanism of Cs Immobilization within a Sodalite Framework: The Role of Alkaline Cations and the Si/Al Ratio.

Conditioning of radioactive waste generated from the operation of medical institutions, nuclear cycle facilities, and nuclear facilities is important for the safety of the environment. One of the most hazardous radionuclides is radioactive cesium. There is a need for more effective solutions to contain radionuclides, especially cesium (Cs+). Geopolymers are promising inorganic materials that can provide a large active surface area with adjustable porosity and binding capacity. The existence of nanosized zeolite-like structures in aluminosilicate gels was shown earlier. These structures are candidates for immobilizing radioactive cesium (Cs+). However, the mechanisms of their interactions with the aluminosilicate framework related to radionuclide immobilization have not been well studied. In this work, the influence of alkaline cations (Na+ or K+) and the aluminosilicate framework structure on the binding capacity and mechanism of interaction of geopolymers with Cs+ is explored in the example of a sodalite framework. The local structure of the water molecules and alkaline ions in the equilibrium state and its behavior when the Si/Al ratio was changed were studied by DFT.

Advances in the management of radioactive wastes and radionuclide contamination in environmental compartments: a review.

Several anthropogenic activities produce radioactive materials into the environment. According to reports, exposure to high concentrations of radioactive elements such as potassium (40K), uranium (238U and 235U), and thorium (232Th) poses serious health concerns. The scarcity of reviews addressing the occurrence/sources, distribution, and remedial solutions of radioactive contamination in the ecosystems has fueled data collection for this bibliometric survey. In rivers and potable water, reports show that several parts of Europe and Asia have recorded radionuclide concentrations much higher than the permissible level of 1 Bq/L. According to various investigations, activity concentrations of gamma-emitting radioactive elements discovered in soils are higher than the global average crustal values, especially around mining activities. Adsorption technique is the most prevalent remedial method for decontaminating radiochemically polluted sites. However, there is a need to investigate integrated approaches/combination techniques. Although complete radionuclide decontamination utilizing the various technologies is feasible, future research should focus on cost-effectiveness, waste minimization, sustainability, and rapid radionuclide decontamination. Radioactive materials can be harnessed as fuel for nuclear power generation to meet worldwide energy demand. However, proper infrastructure must be put in place to prevent catastrophic disasters.

Removal of cobalt and strontium by adsorption using Brewer's spent grain formed by pyrolysis.

One byproduct of brewing beer is Brewer's spent grain (BSG), which is reused in animal feed. However, BSG has valuable potential for other products such as biochar because of its high protein and fiber content. Radioactive waste is one of the biggest concerns in Korea because of the permanent shutdown of the Gori nuclear power plant. In this study, we aimed to use BSG-850, a biochar originating from BSG after pyrolysis at 850 °C, for the adsorption of cobalt (Co) and strontium (Sr), which are two radionuclides that contribute to radioactive waste. The adsorption capacity of Co and Sr was reinforced with increased temperature which are 3.304, 4.659, 5.516 mg/g (Co) and 1.462, 2.54, 3.036 mg/g (Sr) at 298, 308, and 318 K, respectively. The reusability of BSG-850 capacity was 75.3, 47.8, 43.6, 36.2% and 93.6, 84.2, 57.2, and 32.7% after 1, 2, 3, and 4 cycles, for Co and Sr, respectively. In the presence of other competitive ions, the adsorption capacity decreased. The adsorption capacity and properties of BSG-origin biochar for Co and Sr were confirmed and BSG can be a desirable option for solving radioactive waste issue.

Survivability and proliferation of microorganisms in bentonite with implication to radioactive waste geological disposal: strong effect of temperature and negligible effect of pressure.

As bentonite hosts a diverse spectrum of indigenous microorganisms with the potential to influence the long-term stability of deep geological repositories, it is essential to understand the factors influencing microbial activity under repository conditions. Here, we focus on two factors, i.e., temperature and swelling pressure, using a suspension of Cerny Vrch bentonite to boost microbial activity and evaluate microbial response. Suspensions were exposed either to different pressures (10, 12 and 15 MPa; to simulate the effect of swelling pressure) or elevated temperatures (60, 70, 80 and 90 °C; to simulate the effect of cannister heating) for four weeks. Each treatment was followed by a period of anaerobic incubation at atmospheric pressure/laboratory temperature to assess microbial recovery after treatment. Microbial load and community structure were then estimated using molecular-genetic methods, with presence of living cells confirmed through microscopic analysis. Our study demonstrated that discrete application of pressure did not influence on overall microbial activity or proliferation, implying that pressure evolution during bentonite swelling is not the critical factor responsible for microbial suppression in saturated bentonites. However, pressure treatment caused significant shifts in microbial community structure. We also demonstrated that microbial activity decreased with increasing temperature, and that heat treatment strongly influenced bentonite microbial community structure, with several thermophilic taxa identified. A temperature of 90 °C proved to be limiting for microbial activity and proliferation in all bentonite suspensions. Our study emphasizes the crucial role of a deep understanding of microbial activity under repository-relevant conditions in identifying possible strategies to mitigate the microbial potential within the deep geological repository and increase its long-term stability and safety.

Removal of CrO42-, a Nonradioactive Surrogate of 99TcO4-, Using LDH-Mo3S13 Nanosheets.

Removal of chromate (CrO42-) and pertechnetate (TcO4-) from the Hanford Low Activity Waste (LAW) is beneficial as it impacts the cost, life cycle, operational complexity of the Waste Treatment and Immobilization Plant (WTP), and integrity of vitrified glass for nuclear waste disposal. Here, we report the application of [MoIV3S13]2- intercalated layer double hydroxides (LDH-Mo3S13) for the removal of CrO42- as a surrogate for TcO4-, from ppm to ppb levels from water and a simulated LAW off-gas condensate of Hanford's WTP. LDH-Mo3S13 removes CrO42- from the LAW condensate stream, having a pH of 7.5, from ppm (∼9.086 × 104 ppb of Cr6+) to below 1 ppb levels with distribution constant (Kd) values of up to ∼107 mL/g. Analysis of postadsorbed solids indicates that CrO42- removal mainly proceeds by reduction of Cr6+ to Cr3+. This study sets the first example of a metal sulfide intercalated LDH for the removal of CrO42-, as relevant to TcO4-, from the simulated off-gas condensate streams of Hanford's LAW melter which contains highly concentrated competitive anions, namely F-, Cl-, CO32-, NO3-, BO33-, NO2-, SO42-, and B4O72-. LDH-Mo3S13's remarkable removal efficiency makes it a promising sorbent to remediate CrO42-/TcO4- from surface water and an off-gas condensate of nuclear waste.

A Scintillator Array Table with Spectroscopic Features.

In the framework of radioactive material handling, such as in radwaste sorting and segregation operations, the availability of a simple tool to quickly detect and locate gamma radiation spots can be quite convenient. Additional spectroscopic features, even with moderate energy resolutions, could provide a useful benefit. As a proof of principle for such a tool, we developed a gamma detector prototype featuring an array of 10 × 10 CsI(Tl) scintillators (1 × 1 × 1 cm3) providing readouts by means of a corresponding array of 6 × 6 mm2 silicon photo multipliers (SiPM). Such a detector table could be easily incorporated into a work desk for quick scanning of possibly radioactive objects. The proposed detector has a good counting efficiency and energy resolution, while the simulations and tests show interesting hot-spot localization capabilities.

Evaluation of thermal plasma process for treatment disposal of solid radioactive waste.

The management of radioactive waste is a worldwide activity based on the guidelines of the International Atomic Energy Agency (IAEA), and all stages of management require scientifically proven methods for possible deployment. The management of radioactive waste is a huge challenge due to the high risk in the collection, gathering, transport, handling, and storage. In this study, a thermal plasma treatment process was evaluated for its efficiency to process solid radioactive waste. Experiments were carried out with the application of stable isotopes of Lead, Iodine, Cobalt, and Cesium. After the thermal plasma treatments, the slag and the residual gas were analyzed to verify the influence of process time and discharge power on the efficiency of the process. The treatment for 25 min and 10 kW was sufficient to reduce the mass by 50% of the slag. When the applied power was increased to 15 kW, an expressive reduction in the treatment time (10 min) was able to promote the same mass reduction. The results indicated that the treatment of radioactive waste by thermal plasma is a promising method to manage and reduce the mass and volume for the final disposal.

Insight into the role of temperature, time and pH in the effective zirconium retention using clay minerals.

The use of zirconium in chemical industries generates a potential risk of Zr contamination in the environment, with particular concern for the decommissioning of uranium-graphite reactors. Among the natural adsorbents employed for the treatment of nuclear waste, clay minerals showed a very high affinity adsorption for radionuclides, but the influence of the chemical composition, pressure, temperature and time reaction have not yet been analysed on deep. Thus, the objective of this research is to explore several experimental conditions for an actual prediction of the behaviour of zirconium immobilization by clay minerals. The results have shown that factors such as zirconium cation nature (Zr4+ or ZrO2+), temperature, time and pH influence the extent of zirconium immobilization by clay minerals and the zirconium phases generated. At moderate conditions, zirconium tectosilicates are formed and evolve to zircon at high temperature and a longer time reaction.

Removal of Cs-137 Radionuclide by Resorcinol-Formaldehyde Ion-Exchange Resins from Solutions Simulating Real Liquid Radioactive Waste.

The efficiency of the removal of Cs-137 radionuclides with porous and non-porous resorcinol−formaldehyde resins from alkaline solutions simulating the composition of real liquid radioactive waste (LRW) streams has been evaluated. Resins were synthesized through the polycondensation of resorcinol and formaldehyde in an alkaline medium at a molar ratio of 1.8/2.2 and a temperature of 210 °C. The Cs-137 distribution coefficients on RFRs in alkaline solutions simulating LRW were above 103 mL/g under static sorption conditions. In a model solution with pH 11, the full dynamic sorption capacity of non-porous RFR was 0.178 mmol/g. The values of the full dynamic sorption capacities of porous RFRs were 0.274 and 1.035 mmol/g for resins obtained with calcium carbonate and toluene as templates, respectively. When the sizes of RFR beads increased two-fold, the volume until 5% cesium breakthrough decreased by 20−40%. The most pronounced beneficial effect of the RFR's porosity was observed at flow rates from 25 to 50 BV/h. It was shown that the negative effect of metal cations on Cs-137 uptake increases in the following order: Na+ < Mg2+ < Ca2+ < K+. The number of bed volumes of LRW-simulating solution decontaminated with RFRs until 5% cesium breakthrough was above 450; that is higher than the value of known commercially available analogs. The latter shows that the developed RFRs are promising for application in technological schemes of alkaline LRW processing.

Methodological developments and practice in characterisation of unconventional and legacy waste.

Radioactive waste management requires planned and systematic actions to provide confidence that the entire system, processes and final products will satisfy given requirements for quality. The characterisation process is dependent on setting clear characterisation objectives and gathering the right information to underpin the decisions that need to be taken to manage the waste safely. This paper reviews experience of characterisation of waste generated from past nuclear activities that were not conducted in compliance consistent with current criteria, or from unexpected situations that were not planned for. This experience shows that the development of a reliable and efficient characterisation and categorisation methodology is a common challenge for such wastes, referred to here as unconventional and legacy (UL) waste. Through the activites of the Nuclear Energy Agency Expert Group on the Characterisation of Unconventional and Legacy Waste, consideration has been given to widely used waste stream characterisation procedures and methods that were originally developed primarily for application in conventional decommissioning work. Although they provide a substantial basis for characterisation, there are various additional factors that commonly need to be taken into account in the case of UL waste. By analysing the challenges and lessons learned from a variety of case studies and other international experience, it has been possible to identify opportunities for adaptations and enhancements to these characterisation methologies, and these are set out and explained. The need for integration of waste characterisation with other aspects of strategic planning for UL waste management is discussed, including characterisation to address any non-radiological hazards. The analysed case studies have also highlighted the importance of developing a robust legislative and regulatory framework in parallel with an appropriate waste infrastructure to treat, store and dispose of UL waste. Finally, the basic features of a UL waste characterisation roadmap are presented, including the interactions within a wider UL waste management programme and key areas for further consideration and possible development. It is anticipated such work can be supported by continued international cooperation.

Approaches to the definition of potentially exposed groups and potentially exposed populations of biota in the context of solid radioactive waste.

A methodology for addressing the biosphere in safety assessments for solid radioactive waste disposal was developed through theme 1 of the IAEA coordinated research project on BIOsphere Modelling and ASSessment (BIOMASS) that ran from 1996 to 2001. This methodology provided guidance on how the biosphere can be addressed in safety assessments for disposal of solid radioactive waste. Since the methodology was developed, it has proven useful and has been widely referenced in assessments in a diversity of contexts encompassing both near-surface and deep geological disposal of solid radioactive waste. The principles that could be adopted for defining potentially exposed groups (PEGs) were an important aspect in the original BIOMASS methodology as the endpoint of an assessment usually includes the evaluation of individual dose or risk to human health. Identification of PEGs and definition of their characteristics are usually made to be consistent with the biosphere system description being developed, acknowledging that due to inherent uncertainties in projecting future human behaviour, the biosphere models adopted for assessing safety of a disposal system can only be illustrative. Since the publication of the original BIOMASS methodology, consideration has been extended to include potentially exposed populations of biota (PEPs), in the context of dose assessment and protection of the environment. Considering the need for the development of transfer pathways from a source term to an end point (for either PEGs or PEPs), the exposure modes that may occur and those to be assessed quantitatively should be identified. Within an expert working group (WG6) of the second phase of the IAEA coordinated project Modelling and Data for Radiological Impact Assessments (MODARIA II), the experience of participating organisations has been collected on topics associated with the definition of PEGs and PEPs using a questionnaire. The objective of the questionnaire was to review the current status and on-going discussions on the handling of issues related to definitions of PEGs and PEPs as an input to the development of biosphere models for assessing radiological impacts on human health and the environment. The answers received to the questionnaire provided a clear overview of the progress that has been made since the original BIOMASS methodology was published, together with the lessons learned from the application of that methodology in the development of safety cases. This paper summarises the questionnaire responses in five subject areas: (1) environment of the PEGs and its evolution; (2) linking the choice of PEGs to these environments; (3) food habits and consumption rates; (4) populations of non-human biota (PEPs) and (5) national and international regulations and guidance. We illustrate how the results of the questionnaire have been used to enhance the original BIOMASS methodology (IAEA Enhanced BIOMASS Methodology Report in press).