Heliyon, Volume 8, Issue 11, E11758 – November 2022

Encina Gutierrez-Carazo, James Dowle, Frederic Coulon, Tracey Temple,and Melissa Ladyman

There is a trend toward the use of Insensitive High Explosives (IHE) in both military and civil applications as they are intended to be less prone to accidental detonation compared to traditional explosive fills. This has driven the development of new explosive formulations containing different chemical compounds whose behaviour once they are released into the environment is not fully understood. To date, research into the toxicity and the persistence of IHE compounds in the environment is scarce and little has been described about how they interact with, or move through soil. In this work, the transport of two IHE constituents, 2,4-dinitroanisole (DNAN) and 3-nitro-1,2,4-triazol-5-one (NTO), through two soil types (sand and sandy loam) was simulated in GoldSim using a stochastic approach. The simulation outputs were validated by comparison to results from empirical soil column experiments. Sorption of the IHE constituents to the soil was the most significant factor in predicting when the contaminants eluted from the soil column. Sensitivity analysis demonstrated that variation in the matrix water partition coefficient (Kd) had the greatest influence when used to predict the IHE compounds transport. Kd was measured empirically and, as expected, it was low in sand for NTO (0.334 L kg−1) and DNAN (0.401 L kg−1), suggesting high mobility. While in sandy loam Kd for NTO (0.242 L kg−1) was similar to one obtained in sand, it was significantly higher for DNAN (9.128 L kg−1), explaining the high retention and adsorption in the sandy loam soil. The use of stochastic modelling to estimate IHE breakthrough concentrations could enable the uncertainty inherent in environmental systems to be embedded into simulations, thus increasing their representativeness. This study is the first step toward proactive management of IHE in the environment, and may support decision making for remediation and mitigation strategies in different environments.

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Energies – September 2022

Jiri Landa and Milan Hokr

A model of contaminant transport from a repository to the biosphere is one of the major needs in the safety assessment of the geological disposal of spent nuclear fuel. This work deals with the development of a procedure that obtained characteristic data from the transport path by postprocessing the results of the 3D flow and transport models, according to the repository concept for the Czech Republic. Postprocessing was used to map the entire transport pathway, which included the smallest tracer flows; therefore, it is called the “integral method”. The results are the characteristics of the storage system, such as: transport path length, flow time, total dilution, groundwater flow, longitudinal dispersivity, porosity, etc. These acquired characteristics can be used directly in safety analyses or to narrow the selection of candidate sites. Furthermore, these parameters were used to set up a model with lumped parameters (in this case, created in the GoldSim SW environment). Even only one “Pipe” component, after being properly set up, shows almost identical results to the entire 3D model. Based on the results of the 3D model, it is possible to set up a lumped parameter model that accurately simulates the transport path and can perform further calculations of a larger number of contaminants in repeated runs, e.g., with stochastic input data, which would be very laborious (or not possible at all) with the 3D model. 

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Geophysical Research Abstracts, Vol. 9, 05821 – September 2022

John Tauxe and Paul Black, Neptune and Company; Vaclav Hanusik, VUJE Trnava, Inc.

This paper discusses the performance assessment of a low- and intermediate-level waste repository in the Slovak Republic.

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MRS Advances – January 2021

Joseph N.P. Lillington, Thomas L. Goût, Mike T. Harrison, Tajudeen M. Iwalewa and Ian Farnan

The vitrification of radioactive waste within glass and subsequent disposal within a geological disposal facility (GDF) requires a comprehensive understanding of the effect of glass dissolution on GDF performance. This paper aims to analyse the effect of both high-level and intermediate-level waste (HLW and ILW) glass dissolution source terms on radionuclide release into the geosphere just above the disposal vault (the ‘crown’). Radionuclide migration was simulated in GoldSim for HLW in either granite or clay host rocks with a bentonite buffer using carbon steel or copper canisters, whereas ILW simulations considered either granite or clay host rocks, in either bentonite buffer or cement backfill, using concrete or cast-iron canisters. Glass dissolution source terms were varied by coupling GoldSim and MATLAB to modify the initial, residual, and resumption dissolution rates of the glass or by applying the analytical GRAAL model to glass dissolution. HLW glass results indicate no preference of granite over clay host rocks for a given canister type but that a copper canister is preferable to steel. ILW results suggest that a granite–bentonite–cast-iron environment yields lowest crown activities with cast-iron preferable to concrete as the canister, bentonite preferable to cement as the buffer/backfill, and granite preferable to clay as the host rock. Varying glass dissolution source terms (initial, residual, and resumption dissolution rates) had an understood effect on radionuclide migration, although changes were arguably insignificant considering peak crown activity for both HLW and ILW.

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NORM Symposium – December 2020

K. Catlett, P. Black, R. Perona, S. Van Sickle, G. Occhiogrosso, A. Fleury

Naturally occurring radioactive material (NORM) and technologically enhanced NORM (TENORM) can be disposed of at a variety of sites, including Resource Conservation and Recovery Act (RCRA) landfills where low levels of radioactive waste are accepted. The performance of the landfill with regard to radiological operating permit requirements is often assessed using a model constructed with the residual radioactivity (RESRAD) computer program, developed by Argonne National Laboratory for the U.S. Department of Energy (DOE). RESRAD supports the evaluation of several environmental transport pathways related to a radionuclide-contaminated soil source term, but it was not conceived as a model for the evaluation of landfill radiological performance. A more comprehensive and realistic model can be developed using the GoldSim dynamic Monte Carlo modeling software. Performance Assessment (PA) computer models have been developed using GoldSim software for and by a variety of organizations, including the US Department of Energy, the U.S. Nuclear Regulatory Commission and corporate waste disposal companies. The RESRAD computer model was specifically developed for calculating soil cleanup criteria and radiological dose and cancer risk from residual radioactive material in soil. To evaluate site-specific conditions, users may select from among a number of available environmental transport and exposure pathways and modify “default” parameter values. In GoldSim, a user must construct the model “from scratch.” However, this modeling is facilitated by a number of specialized elements available in GoldSim to support a radiological mass transport model. These include elements for defining radiological decay and ingrowth, container failure and radiological release, advective and diffusive transport, and other processes. Advantages afforded by the use of RESRAD for modeling radiological dose for a RCRA landfill include ease of use and that it is commonly known. GoldSim allows for considerably more flexibility and site-specificity than RESRAD, including evaluation of potentially relevant environmental transport processes not supported in RESRAD. The probabilistic modeling capabilities of GoldSim also far exceed those of RESRAD. The pros and cons of RESRAD and GoldSim for this modeling problem are explored with a focus on identifying approaches and critical factors in identifying the appropriate platform.

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Proceedings of the 2018 Waste Management Symposium – March 2018

K.P. Lee, R. Andrews, N. Hasan, R. Senger, M. Kozak, A. K. Wahi, and W. Zhou

The US Department of Energy (DOE) Office of River Protection and its subcontractors performed a performance assessment for the near-surface disposal of low-level and mixed low-level waste at the Hanford Integrated Disposal Facility. Computer simulations were performed to evaluate whether or not the disposal facility would comply with the performance objectives specified by the DOE. The evaluation was performed using numerical models to simulate source term releases from vitrified and cement-based waste forms. Source term releases were subsequently transported through the facility into the natural system beneath the facility (comprised of an 85-meter thick vadose zone and thinner but highly conductive saturated zone overlying basalt) to a point of compliance 100-meters downstream the disposed waste. Due to the differing scales in the finite difference models developed for the source terms and those developed for the natural system, numerical models for source term release and natural system flow and transport were not directly coupled. Instead, the output from the source term simulations were used as input to the natural system flow and transport simulations. The decoupling of the modeled systems makes it difficult to explore synergies and investigate the impact of parameter uncertainties. In order to explore system synergies and evaluate parameter uncertainty, an integrated system model was developed using GoldSim that includes source term release models, natural system transport models, and dose calculations. This paper describes how the numerical models were used to develop abstractions that could be incorporated into the integrated system-level model that was then used to explore system synergies and parameter uncertainties.

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Nuclear Engineering and Technology – August 2017

Chih-Lung Chen, Taiwan Power Company; Tsing-Hai Wang, National Tsing Hua University

Diffusion is a crucial mechanism that regulates the migration of radioactive nuclides. In this study, an innovative numerical method was developed to simultaneously calculate the diffusion coefficient of both parent and, afterward, series daughter nuclides in a sequentially reactive through-diffusion model. Two constructed scenarios, a serial reaction (RN_1 → RN_2 → RN_3) and a parallel reaction (RN_1 → RN_2A + RN_2B), were proposed and calculated for verification. First, the accuracy of the proposed three-member reaction equations was validated using several default numerical experiments. Second, by applying the validated numerical experimental concentration variation data, the as-determined diffusion coefficient of the product nuclide was observed to be identical to the default data. The results demonstrate the validity of the proposed method. The significance of the proposed numerical method will be particularly powerful in determining the diffusion coefficients of systems with extremely thin specimens, long periods of diffusion time, and parent nuclides with fast decay constants.

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Nuclear Engineering and Design – March 2017

Seunghee Lee and Juyoul Kim, FNC Technology Co.

Great attention has been recently paid to the post-closure safety assessment of low- and intermediate-level radioactive waste (LILW) disposal facility for disused sealed radioactive sources (DSRSs) around the world. Although the amount of volume of DSRSs generated from industry, medicine and research and education organization was relatively small compared with radioactive wastes from commercial nuclear power plants, some DSRSs can pose a significant hazard to human health due to their high activities and long half-lives, if not appropriately managed and disposed. In this study, post-closure safety assessment was carried out for DSRSs generated from 1991 to 2014 in Korea in order to ensure long-term safety of near surface disposal facilities. Two kinds of disposal options were considered, i.e., engineered vault type disposal facility and rock-cavern type disposal facility. Rock-cavern type disposal facility has been under operation in Gyeongju city, republic of Korea since August 2015 and engineered vault type disposal facility will be constructed until December 2020 in the vicinity of rock-cavern disposal facility. Assessment endpoint was individual dose to the member of critical group, which was modeled by GoldSim, which has been widely used as probabilistic risk analysis software based on Monte Carlo simulation in the area of safety assessment of radioactive waste facilities.

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Proceedings of The 20th Pacific Basin Nuclear Conference. PBNC 2016. – February 2017

Hong-hui Li, China Institute for Radiation Protection

In China, “The Law on Prevention and Control for Radioactive Pollution” issued in 2003 determined that the high-level waste will be disposed in a deep central geological repository. The main work of China Institute for Radiation Protection (CNNC-mandated comprehensive research) about HLW disposal is safety assessment. In 2006–2010, the CIRP have done some of the works about safety criteria and safety requirements: public radiation protection for post-closure of repository: 0.3 mSv/a; timescale: 10,000a. The CIRP also have established SA methodology and routine. Some software about safety assessment such as AMBER, Ecolegy, GoldSim, ProFlow can be familiarly used. The main works in 2014–2017 about the safety assessment that will be done are the research of safety requirements of the EBS and host rock, the research of safety function of the EBS and host rock, establishing the safety indicators’ system of the EBS and host rock, establishing the FEPs list and the scenario analysis in the conceptual and planning stage, the near-field temperature simulation based on the conceptual design of the repository, and the safety assessment of Beishan Preliminary Repository. Some of the above-mentioned work details will be introduced in this paper.

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Chemosphere – November 2016

Jolin WC, University of Connecticut; Kaminski M, Argonne National Laboratory

Procedures for removing harmful radiation from interior and exterior surfaces of homes and businesses after a nuclear or radiological disaster may generate large volumes of radiologically contaminated waste water. Rather than releasing this waste water to potentially contaminate surrounding areas, it is preferable to treat it onsite. Retention barrels are a viable option because of their simplicity in preparation and availability of possible sorbent materials. This study investigated the use of aluminosilicate clay minerals as sorbent materials to retain (137)Cs, (85)Sr, and (152)Eu. To simulate flow within retention barrels, vermiculite was mixed with sand and used in small-scale column experiments. The GoldSim contaminate fate module was used to model breakthrough and assess the feasibility of using clay minerals as sorbent materials in retention barrels.

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Economic and Environmental Geology – August 2016

Seunghee Lee, Juyoul Kim and Sukhoon Kim, FNC Technology Co.

Disused Sealed Radioactive Sources (DSRSs) are stored temporally in the centralized storage facility of Korea Radioactive Waste Agency (KORAD) and planned to be disposed in the low- and intermediate-level radioactive waste (LILW) disposal facility in Gyeongju city. In this study, preliminary post-closure safety assessment was performed for DSRSs in order to draw up an optimum disposal plan. Two types of disposal options were considered, i.e. engineered vault type disposal and rock cavern type disposal which were planned to be constructed and operated respectively in LILW disposal facility in Gyeongju city. Assessment end-point was individual effective dose of critical group and calculated by using GoldSim code.

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Progress in Nuclear Energy – July 2016

Youn-Myoung Lee, Heui-Joo Choi, and Kyungsu Kim, Korea Atomic Energy Research Institute (KAERI)

To compare two options for disposal of spent nuclear fuels (SFs) a generic GoldSim model for deep boreholes for disposal (DBD) of SFs was developed. As a desktop study, nuclide release and transport from a DBD after the closure of a repository were roughly evaluated and compared to a KBS-3 type disposal in a less deep geological repository (DGD). An assessment result from the DBD is shown to be remarkable and seems to give a sufficient radiological safety margin, compared to the DGD, even though this study was done in a very straightforward manner. A remarkable sensitivity of the travel lengths involved in the fractured geological media around the DBD to the exposure dose rates are not observed with rather fast and short travel times for non-sorbing nuclides with long-half lives.

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Progress in Nuclear Energy – July 2016

Jongtae Jeong, Youn-Myoung Lee, Jung-Woo Kim, Dong-Keun Cho, Nak Yul Ko, and Min Hoon Baik, Korea Atomic Energy Research Institute (KAERI)

KAERI developed a reference repository system for the disposal of radioactive wastes resulting from the pyroprocessing of PWR spent nuclear fuels (A-KRS; Advanced Korean Reference Disposal System). To check the design feasibility of this system, we developed a total system performance assessment (TSPA) tool using Goldsim program and assessed the exposure dose rates for the reference scenario and three alternative scenarios such as earthquake, well intrusion, and initial defect of waste packages by using this tool. And then, we compared the exposure dose rates for each scenario with a draft supplementary safety goal, 10 mSv/yr, which was suggested by the regulatory body in Korea.

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Progress in Nuclear Energy – April 2016

Youn-Myoung Lee, Heui-Joo Choi, Korea Atomic Energy Research Institute (KAERI)

A simple and effective model and a GoldSim template program, by which a probabilistic safety assessment of a conceptual trench-type repository for low- and intermediate level radioactive waste (LILW) disposal can be carried out under various nuclide release scenarios, have been developed. To quantify the exposure dose rates due to nuclide release from the trench and transport through the various pathways possible in the near- and far-fields of the repository system under a base case and some alternative scenarios, illustrative evaluations for a comparison among the scenarios as well as a sensitivity of shortcut pathways generated due to earthquakes on the nuclide transport are made and demonstrated. To this end, by changing the conservative base case nuclide release scenario under which all portions of the cap of the trench are failed unconditionally and immediately after a closure of the repository, a total of four other alternative scenarios were separately evaluated for the total exposure dose rates to the farming exposure group and then compared to the base case results.

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Procedia Chemistry – January 2016

Heejae Ju, Inhye Hahm, Sungjune Sohn, and Il Soon Hwang, Seoul National University

We have conducted a long-term environmental assessment of a geological repository for Intermediate Level Wastes (ILW) arising from PyroGreen processes that has been developed to decontaminate all HLW from the pyrochemical partitioning of spent nuclear fuels (SNF). PyroGreen process has been designed so that final ILW can meet conservative acceptance criteria such as one established for the Waste Isolation Pilot Plant (WIPP) in U.S.A. The nuclide inventory of final vitrified PyroGreen waste is calculated using ORIGEN 2.1 based on the design decontamination factor of PyroGreen processes applied to 18,171 metric tons of PWR SNF with 45 GWD/MTU burnup. Using GoldSim model, the environmental impact of ILW upon geological disposal at an intermediate depth. Among radioactive nuclides, Ra226, Rn222 and Sn126 are identified as key contributors to radiological dose for general public. The environmental impact of PyroGreen wastes satisfies the Korean dose limit of 0.1 mSv/year with sufficiently high margin. Sensitivity studies have shown that the predicted dose can vary significantly by distribution coefficient of Ra226 and Rn222, solubility limit of Se79.

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Journal of Sustainable Development of Energy, Water and Environment Systems, Vol. 4 No. 3 – January 2016

Lucie Baborová, Dušan Vopálka, Aleš Vetešník, and Eva Hofmanová, Czech Technical University in Prague

The study deals with sorption and diffusion behaviour of strontium in Czech bentonite B75. The study is a part of a research on reactive transport of radioactive contaminants in barrier materials of a deep geological repository of radioactive waste in the Czech Republic. Series of sorption and diffusion experiments with Sr and non-activated Ca bentonite B75 produced in the Czech Republic were performed in two background solutions (CaCl2 and NaCl). On the basis of sorption batch experiments the kinetics of strontium sorption on bentonite was assessed and the sorption isotherms for various experimental conditions were obtained. As a result of performed diffusion experiments the parameters of diffusion (i.e. effective diffusion coefficient De and apparent diffusion coefficient Da) were determined. The observed discrepancies between sorption characteristics obtained from the sorption and diffusion experiments are discussed.

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Mineralogical Magazine – November 2015

R. C. Walke, M. C. Thorne, J. T. Smith, and R. Kowe

Radioactive Waste Management Limited (RWM) is tasked with implementing geological disposal of the United Kingdom’s (UK) higher activity radioactive wastes. This paper describes how RWM’s biosphere modelling capability has been extended from a solely terrestrial model to allow potential contaminant releases to estuarine, coastal and marine systems around the UK to be represented. The new models aim to strike a balance between being as simple as can be justified, erring on the side of conservative estimates of potential doses, while also representing the features and processes required to reflect and distinguish UK coastal systems. Sediment dynamics (including meandering of estuaries and sediment accumulation) are explicitly represented in a simplified form that captures the accumulation and remobilization of radionuclides. Long-term transitions between biosphere systems (such as from a salt marsh to a terrestrial system) are outside the scope of the study. The models and supporting data draw on information about the UK that is representative of present-day conditions and represent potential exposures arising from both occupational and recreational habits.

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Mineralogical Magazine – November 2015

Charalampos Doulgeris, Paul Humphreys, and Simon Rout

Carbon-14 (C-14) is a key radionuclide in the assessment of a geological disposal facility (GDF) for radioactive waste. In the UK a significant proportion of the national C-14 inventory is associated with reactor-core graphite generated by the decommissioning of the UK's Magnox and AGR reactors. There are a number of uncertainties associated with the fate and transport of C-14 in a post-closure disposal environment that need to be considered when calculating the radiological impacts of C-14-containing wastes. Some of these uncertainties are associated with the distribution of C-14-containing gaseous species such as ¹⁴CH₄ and ¹⁴CO₂ between the groundwater and gaseous release pathways. As part of the C14-BIG programme, a modelling framework has been developed to investigate these uncertainties. This framework consists of a biogeochemical near-field evolution model, incorporating a graphite carbon-14 release model, which interfaces with a geosphere/biosphere model. The model highlights the potential impact of the microbial reduction of ¹⁴CO₂ to ¹⁴CH₄, through the oxidation of H₂, on C-14 transport. The modelling results could be used to inform the possible segregation of reactor graphite from other gasgenerating wastes.

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Mineralogical Magazine – November 2015

R.J. Winsley, T.D. Baldwin, T.W. Hicks, R.M. Mason, and P.N. Smith

A geological disposal facility (GDF) will include fissile materials that could, under certain conditions, lead to criticality. Demonstration of criticality safety therefore forms an important part of a GDF's safety case. Containment provided by the waste package will contribute to criticality safety during package transport and the GDF operational phase. The GDF multiple-barrier system will ensure that criticality is prevented for some time after facility closure. However, on longer post-closure timescales, conditions in the GDF will evolve and it is necessary to demonstrate: an understanding of the conditions under which criticality could occur; the likelihood of such conditions occurring; and the consequences of criticality should it occur. Work has addressed disposal of all of the UK's higher-activity wastes in three illustrative geologies. This paper, however, focuses on presenting results to support safe disposal of spent fuel, plutonium and highly-enriched uranium in higher-strength rock.

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Publication for the International Atomic Energy Agency, IAEA-CN-226-34 – June 2015

R. Stoll, J. Greeves, and J. Voss with Predicus LLC, USA; A. Keizur and A. Neir with Golder Associates Inc., USA; N. Saraeva and W. Nutt with Argonne National Laboratory, USA

An Execution Strategy Analysis (ESA) capability and tool is being developed to evaluate alternative execution strategies for future deployment of a consolidated Interim Storage Facility (ISF) using a consent-based siting process per the Administration’s Strategy for the Management and Disposal of Used Nuclear Fuel and High-Level Radioactive Waste. Application of an ESA approach not only leverages on but also goes beyond traditional project analysis tools. The ESA tool allows for on-going performance assessment of the evolving project execution plan that takes into account significant assumptions, risks, and uncertainties throughout the project lifecycle. The ESA process and tool are used to support the development of plans, budgets, and alternative execution/ implementation strategies for meeting the goals in the Strategy. The project is being applied in a dynamic probabilistic simulation model using GoldSim.

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Conference Proceedings, WM2015 Conference, Phoenix, Arizona, USA – March 2015

Bernt Haverkamp, DBE Technology GmbH and Heinz Kroeger, TÜV NORD EnSys Hannover

The Saakadze disposal facility is located about 40 km from Tbilisi and was planned and constructed during Soviet times as Radon-type surface facility to accommodate up to 600 m3 of low and intermediate level waste generated on the territory of Georgia. The disposal facility was operated from 1963 until its closure in 1995. The vast majority of waste in the Saakadze facility has been disposed of in two near surface concrete vaults with typical Radon-type dimensions, which cover layers already show significant structural damages. For the long-term calculations a mathematical model has been developed using the GoldSim simulation environment. GoldSim simulates the material transport and takes care of radioactive decay and the ingrowth of daughter nuclides.

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TOC-WP-14-4902 -FP Revision 0, Prepared for the U.S. DOE – January 2015

M. Bergeron, S. Mehta, W.J. McMahon, M. Kozak, A. Aly, M. Connelly, K. Singleton, S. Eberlein, C. Kemp, and R.D. Hildebrand

A performance assessment (PA) of a Single-Shell Tank Waste Management Area located at the U.S. Department of Energy's (DOE) Hanford Site in southeastern Washington is being conducted to fulfill permitting requirements. Uncertainty and sensitivity analyses using a system level GoldSim model is being used to help quantify the importance of key input parameters on transport behavior and dose.

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Presentation, PSAM12: Probabilistic Safety Assessment & Management Conference – June 2014

David Esh and Christopher Grossman, US Nuclear Regulatory Commission

Uncertainty and sensitivity analyses are an integral part of probabilistic assessment methods used to evaluate the safety of a variety of different systems. In many cases the systems are complex, information is sparse, and resources are limited. Models are used to represent and analyze the systems. To incorporate uncertainty, the developed models are commonly probabilistic. Uncertainty and sensitivity analyses are used to focus iterative model development activities, facilitate regulatory review of the model, and enhance interpretation of the model results. A large variety of uncertainty and sensitivity analyses techniques have been developed as modeling has advanced and become more prevalent. This paper compares the practical performance of six different uncertainty and sensitivity analyses techniques over ten different test functions under different noise levels. In addition, insights from two real-world examples are developed.

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Physics and Chemistry of the Earth – April 2014

M. Felipe-Sotelo, J. Hinchliff, N.D.M. Evans, D. Read, Loughborough University; D. Drury, Golder Associates; S. Williams, Nuclear Decommissioning Authority

The function of the backfill material in a geological disposal facility (GDF) is to chemically condition the environment of the near field and thereby chemically retard the transport of the radionuclides present in the waste. This function of the backfill material is usually referred to as chemical containment. Diffusion experiments are being carried out over periods up to four years to assess the diffusion of Cs, Ni, Eu, Th, U and I (as I⁻) through Nirex Reference Vault Backfill (NRVB). This paper shows the results obtained during the first two years for experiments undertaken using ¹³⁷Cs and ¹²⁵I⁻ tracers with and without carrier. Comparison is made to tritiated water under identical experimental conditions. Migration profiles have been obtained and the relative retention of each radionuclide has been confirmed using digital autoradiography. Transport modelling using GoldSim has replicated experimental observations, producing comparable partition ratios (R_d) to those reported in the literature.

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Progress in Nuclear Energy, Vol. 67, pgs. 88-97 – August 2013

Michal Panik and Vladimir Necas of Slovak University of Technology in Bratislava

The article is focused on modeling and calculation of long-term radiation impact on inhabitants living near decommissioned nuclear installations. Models (scenarios) of various building applications were simulated using GoldSim software with Radionuclide Transport Module. Scenarios were selected according to information from the civil engineering business to cover the types of buildings most suitable for application of conditionally cleared material. The results of the calculations showed that conditional clearance represents no significant safety issue in the long-term. Calculated individual effective doses received by inhabitants did not exceed the given dose constraint (10 μSv/year) in case of any scenario evaluated. Detailed and transparent studies of the long-term impact of conditionally cleared materials are important especially for winning of public acceptance.

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Workreport 2013-25, Posiva Oy, Eurajoki, Finland – August 2013

Jose Luis Cormenzana

In Posiva Oy´s Safety Case "TURVA-2012", the repository system scenarios leading to radionuclide releases were been identified. Three potential causes of canister failure and radionuclide release were considered: (i) the presence of an initial defect in the copper shell of one canister that penetrates the shell completely, (ii) corrosion of the copper overpack, that occurs more rapidly if buffer density is reduced, e.g. by erosion, (iii) shear movement on fractures intersecting the deposition hole. All three failure modes were analysed deterministically. This report describes a probabilistic sensitivity analysis (PSA) for the "initial defect in the canister" reference model.

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Physics and Chemistry of the Earth – July 2013

Alexander Carter, Martin Kelly, and Lucy Bailey, Nuclear Decommissioning Authority

This paper presents a simplified analytical model to provide insight into the key performance measures of a generic disposal system for high level waste within a geological disposal facility. The model assumes a low solubility waste matrix within a corrosion resistant disposal container surrounded by a low permeability buffer. Radionuclides migrate from the disposal area through a porous geosphere to the biosphere and give a radiological dose to a receptor. The system of equations describing the migration is transformed into Laplace space and an approximation used to determine peak values for the radionuclide mass transfer rate entering the biosphere. Results from the model are compared with those from more detailed numerical models for key radionuclides in the UK high level waste inventory. Such an insight model can provide a valuable second line of argument to assist in confirming the results of more detailed models and build confidence in the safety case for a geological disposal facility.

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Conference Proceedings, WM2013 Conference – February 2013

B. Haverkamp, J. Krone, I. Shybetskyi

The Radioactive Waste Disposal Facility (RWDF) Buryakovka was constructed in 1986 as part of the intervention measures after the accident at Chernobyl NPP (ChNPP). Today, RWDF Buryakovka is still being operated but its maximum capacity is nearly reached. Plans for enlargement of the facility exist since more than 10 years but have not been implemented yet. A safety analysis report of the facility in its current state (SAR) and a preliminary safety analysis report (PSAR) based on the planned enlargement were prepared. For both safety analysis reports, SAR and PSAR, the assessment of the long-term safety led to results that were either within regulatory limits or within the limits allowing for a specific situational evaluation by the regulator. The repository model was built in GoldSim to carry out the long-term calculations using the Radionuclide Transport Module, which takes not only care of the transport equations describing the mass transport between the different compartments of the model but also of radioactive decay and ingrowth of daughter nuclides with time.

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Conference Proceedings, WM2013 Conference – February 2013

E. Biurrun, A. Lázaro, I. Stefanova, B. Haverkamp, A. Miralles

Due to the early decommissioning of four Water-Water Energy Reactors (WWER) 440-V230 reactors at the Nuclear Power Plant (NPP) near the city of Kozloduy in Bulgaria, large amounts of low and intermediate radioactive waste will arise much earlier than initially scheduled. In or-der to manage the radioactive waste from the early decommissioning, Bulgaria has intensified its efforts to provide a near surface disposal facility at Radiana with the required capacity. To this end, a project was launched to provide the complete technical planning including the preparation of the Intermediate Safety Assessment Report. Preliminary results of operational and long-term safety show compliance with the Bulgarian regulatory requirements. The long-term calculations carried out for the Radiana site are also a good example of how analysis of safety assessment results can be used for iterative improvements of the assessment by pointing out uncertainties and areas of future investigations to reduce such uncertainties in regard to the potential radiological impact. GoldSim was used to estimate the long-term evolution of the future repository at Radiana predicted a maximum total annual dose for members of the critical group, which is carried to approximately 80 % by C-14 for a specific ingestion pathway. Based on this result and the outcome of the sensitivity analysis, existing uncertainties were evaluated and areas for reasonable future investigations to reduce these uncertainties were identified.

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Sandia National Laboratories – January 2013

Teklu Hadgu, Bill W. Arnold, Joon Hyub Lee, Geoff A. Freeze, Palmer Vaughn, Peter N. Swift, Cédric J. Sallaberry

The concept of disposal of high-level radioactive waste in deep boreholes, and probabilistic performance assessment (PA) of a generic disposal system are described. A series of preliminary PA simulations, conducted to evaluate the possible migration of radionuclides to an accessible environment, are presented. The PA simulations provide estimates of radionuclide releases and mean annual radiation doses. The simulations utilized vertical fluxes from a thermal-hydrology process model. Of particular interest to the present study is an analysis of the sensitivity of borehole and surrounding rock permeability values. The analysis provides a bounding exercise of the performance of a generic deep borehole disposal system.

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Mineralogical Magazine – December 2012

R. Kowe and S. Norris

This paper gives an overview of the Nuclear Decommissioning Authority, Radioactive Waste Management Directorate approach to representing the biosphere in post-closure safety assessment studies. The assessments consider potential releases of radionuclides and chemically toxic substances from a geological disposal facility that may reach the biosphere by transport in groundwater and gas. It gives an outline of the key processes and understanding underpinning the representation of the biosphere and how the biosphere may evolve over the long timescales of relevance to post-closure safety. The current biosphere assessment approach and associated models are supported by research studies and collaboration that ensure they are consistent with international recommendations. Research studies are also commissioned to reduce uncertainty surrounding key contaminants and potential exposure pathways and to help ensure that the approach and models are adaptable and flexible enough to incorporate future developments, as the geological disposal programme moves towards site selection.

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Mineralogical Magazine – December 2012

V. Havlová, P. Vecerník, J. Najser, K. Sosna, and K. Breiter

An extensive set of porosity, ε, effective diffusion coefficient, De, and hydraulic conductivity, K, data were obtained from 45 granitic samples from the Bohemian Massif, Czech Republic. The measured dataset can be used to define parameter ranges for data to be used in safety assessment calculations for a deep (>400 m) radioactive waste repository, even though the samples originated from shallower depths (<108 m). The dataset can also be used for other purposes, such as evaluating the migration of contaminants in granitic rock (e.g. from shallow intermediate-level radioactive waste repositories and chemical waste repositories). Sample relaxation and ageing processes should be taken into account in research otherwise migration parameters might be overestimated in comparisons between lab results and those determined in situ.

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WM2012 Conference, Phoenix, Arizona, USA – February 2012

David L. Pentz, Ralph H. Stoll, John T. Greeves, R. Ian Miller, and W. Mark Nutt

The PRISM (Prioritization Risk Integration Simulation Model), a computer model was developed to support the Department of Energy’s Office of Environmental Management (DOE-EM) in its mission to clean up the environmental legacy from the Nation’s nuclear weapons materials production complex. PRISM provides a comprehensive, fully integrated planning tool that can tie together DOE-EM’s projects. It is designed to help DOE managers develop sound, risk-informed business practices and defend program decisions. It provides a better ability to understand and manage programmatic risks. The underlying concept for PRISM is that DOE-EM “owns” a portfolio of environmental legacy obligations (ELOs), and that its mission is to transform the ELOs from their current conditions to acceptable conditions, in the most effective way possible. There are many types of ELOs - - contaminated soils and groundwater plumes, disused facilities awaiting D&D, and various types of wastes waiting for processing or disposal. For a given suite of planned activities, PRISM simulates the outcomes as they play out over time, allowing for all key identified uncertainties and risk factors.

PRISM is based on the GoldSim software that is widely used for risk and performance assessment calculations. PRISM can be run in a deterministic mode, which quickly provides an estimate of the most likely results of a given plan. Alternatively, the model can be run probabilistically in a Monte Carlo mode, exploring the risks and uncertainties in the system and producing probability distributions for the different performance measures.

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WM2012 Conference – February 2012

Joon H. Lee, Bill W. Arnold, Peter N. Swift, Teklu Hadgu, Geoff Freeze, and Yifeng Wang, Sandia National Laboratories

A deep borehole repository is one of the four geologic disposal system options currently under study by the U.S. DOE to support the development of a long-term strategy for geologic disposal of commercial used nuclear fuel (UNF) and high-level radioactive waste (HLW). The immediate goal of the generic deep borehole repository study is to develop the necessary modeling tools to evaluate and improve the understanding of the repository system response and processes relevant to long-term disposal of UNF and HLW in a deep borehole. A prototype performance assessment model for a generic deep borehole repository has been developed using the approach for a mined geological repository. The preliminary results from the simplified deep borehole generic repository performance assessment indicate that soluble, non-sorbing (or weakly sorbing) fission product radionuclides, such as I-129, Se-79 and Cl-36, are the likely major dose contributors, and that the annual radiation doses to hypothetical future humans associated with those releases may be extremely small. While much work needs to be done to validate the model assumptions and parameters, these preliminary results highlight the importance of a robust seal design in assuring long-term isolation, and suggest that deep boreholes may be a viable alternative to mined repositories for disposal of both HLW and UNF.

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WM2012 Conference, Phoenix, AZ – February 2012

David L. Pentz, Ralph H. Stoll, John T . Greeves, Predicus LLC; R. Ian Miller, GoldSim Technology Group; W. Mark Nutt, Argonne National Laboratory

The PRISM (Prioritization Risk Integration Simulation Model), a computer model was developed to support the Department of Energy's Office of Environmental Management (DOE-EM) in its mission to clean up the environmental legacy from the Nation’s nuclear weapons materials production complex. PRISM provides a comprehensive, fully integrated planning tool that can tie together DOE-EM's projects. It is designed to help DOE managers develop sound, risk-informed business practices and defend program decisions. It provides a better ability to understand and manage programmatic risks.

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FIU Electronic Theses Dissertations, Paper S35 – November 2011

Ortez Garay, Cristian A. (Florida International University)

This is a Master's Thesis describing the methodology used to estimate mercury concentrations and risk of exceeding drinking water standards at a receptor well, located near a waste management facility at the Oak Ridge Reservation in Tennessee. GoldSim was used to evaluate the risk based on uncertainty of hydrological and soil parameters used to estimate potential mercury releases from a future containment system. Sensitivity analysis was used to determine the parameters that the model is most sensitive to. Using Monte Carlo analysis, the risk was estimated for various design periods and the overall risk of drinking water contamination was well below standard limits.

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Report prepared for U.S. Nuclear Regulatory Commission Contract No. NRC–02–07–006 – August 2011

Chris Markley et al. (U.S. Nuclear Regulatory Commission)

This document is a user guide that describes the operation and capabilities of the Scoping of Options and Analyzing Risk (SOAR) model. The SOAR model is designed to provide the U.S. Nuclear Regulatory Commission (NRC) staff timely risk and performance insights for a variety of potential high-level radioactive waste (HLW) disposal options. The SOAR model is an analytic scoping tool that the staff will use to develop an effective and efficient risk-informed, performance-based licensing program for geologic disposal of HLW.

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LLWR/ESC/R(11)10028 – May 2011

LLW Repository Ltd

The Low Level Waste Repository (LLWR) is the United Kingdom’s principal facility for the disposal of solid low-level radioactive waste. The LLWR is owned by the Nuclear Decommissioning Authority (NDA) and operated on behalf of the NDA by a Site Licence Company (SLC) – LLW Repository Ltd.

This report is one of a series of reports that present the evidence underpinning the 2011 Environmental Safety Case for the LLWR – the 2011 ESC. The objective of this report is to assess the radiological impacts to humans that may occur in the long term, as a result of disposal of solid radioactive waste at the LLWR.

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WM2011 Conference, Phoenix, AZ – March 2011

Robert Hiergesell and Glenn Taylor, Savannah River National Laboratory

An investigation was conducted to compare and evaluate contaminant transport results of two model codes, GoldSim and PORFLOW, using a simple 1-D string of elements in each code. The comparisons were made solely in terms of the ability of each code to perform contaminant transport. The purpose of the investigation was to establish a basis for, and to validate follow-on work that was conducted in which a 1-D GoldSim model developed by abstracting information from PORFLOW 2-D and 3-D unsaturated and saturated zone models and then benchmarked to produce equivalent contaminant transport results. Although prior validation and verification work has been conducted for both PORFLOW and GoldSim a direct comparison of results from both codes, when evaluating the same model domain, was conducted to confirm this work and justify the benchmarking exercises that compared 1-D to multi-dimensional models.

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WM2011 Proceedings – March 2011

Kevin G. Brown, Vanderbilt University; Frank Smith and Gregory Flach, Savannah River National Laboratory

The Cementitious Barriers Partnership (CBP) Project is a multi-disciplinary, multi-institutional collaboration supported by the United States Department of Energy (US DOE) Office of Waste Processing. The objective of the CBP project is to develop a set of tools to improve understanding and prediction of the long-term structural, hydraulic, and chemical performance of cementitious barriers used in nuclear applications. The project is focused on reducing the uncertainties of current methodologies for assessing cementitious barrier performance and increasing the consistency and transparency of the assessment process. To better characterize the uncertainties in the models used to predict barrier performance, GoldSim is used as a probabilistic framework with interfaces to external codes for specific calculations. A general dynamic-link library (DLL) interface has been developed to link GoldSim with external codes. The DLL that performs the linking function is designed to take a list of code inputs from GoldSim, create an input file for the external application, run the external code, and return a list of outputs, read from files created by the external application, back to GoldSim for analysis. Although currently used by CBP, the DLL is generic and can be used for a wide variety of external codes that need to be examined probabilistically. Use of the DLL to couple external codes to GoldSim helps enable improved risk-informed, performance-based decision-making and supports several of the strategic initiatives in the DOE Office of Environmental Management Engineering & Technology Roadmap.

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Environment Agency Report SC060055 – September 2010

A. Bond, M.J. Egan, R. Metcalfe, P.Robinson, G.Towler (Quintessa)

The primary aim of this report was to summarize and analyse existing knowledge on processes that could influence the performance of an EBS and hence the long-term safety performance of a repository. After reviewing the safety functions attributed to various barrier components by radioactive waste management programmes across the world, and identifying groups of features, events and processes (FEPs) that describe these safety functions and threats to these safety functions, calculations using GoldSim were carried out to explore the significance of each of these FEPs as controls on the performance of barrier components.

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Posiva Working Report 2010-14, Posiva Oy, Finland – March 2010

Veli-Matti Pulkkanen and Henrik Nordman

This report describes the use of GoldSim to model the near-field radionuclide transport processes in a KBS-3V type of nuclear waste repository in Finland.

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Nuclear Engineering and Technology, Vol. 42, No. 1 – February 2010

Yongsoo Hwang and Chul-Hyung Kang, Korea Atomic Energy Research Institute

This paper discusses use of GoldSim to evaluate the potential radionuclide release from a repository based on the Advanced Korean Reference Disposal System (A-KRS). Among other advantages, the development of the A-KRS promises a significant reduction of the repository area due to the removal of decay heat from a certain number of fission products such as Sr-90 and Cs-137.

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Final Report, ESTCP Project ER-200704 – January 2010

Falta, Ronald W.; Newell, Charles J.; Rao, P. Suresh C.; Liang, Hailian; Farhat, Shahla K.; Basu, Nandita

The objective of this project was to develop a new probabilistic remediation modeling program, Probabilistic Remediation Evaluation Model for chlorinated Solvents (PREMChlor), for simultaneously evaluating the effectiveness of source and plume remediation considering the uncertainties in all major parameters, thereby supporting the remediation selection process. PREMChlor was developed by linking the analytical model REMChlor to a Monte Carlo modeling package, GoldSim, via a FORTRAN Dynamic Link Library (DLL) application.

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Proceedings of the 12th International Conference on Environmental Remediation And Radioactive Waste Management ICEM 2009 – October 2009

Yongsoo Hwang and Ian Miller

This paper describes an integrated model developed by the Korean Atomic Energy Research Institute (KAERI) to simulate options for managing spent nuclear fuel (SNF) in South Korea.

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Progress in Nuclear Energy Volume 51, Issues 6-7, pgs. 746-759 – August 2009

Youn-Myong Lee and Yongsoo Hwang, Korea Atomic Energy Research Institute

This article describes a GoldSim model of a hypothetical high level waste repository in South Korea, and describes the model's response to three hypothetical situations (groundwater intrusion, earthquake and accidental human intrusion).

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Scientific Basis for Nuclear Waste Management XXXII, MRS Proceedings, Volume 1124 – October 2008

Karen Pinkston, David W. Esh, Christopher J. Grossman

This paper discusses a GoldSim model built by the U.S. Nuclear Regulatory Commission (NRC) to assess the potential impacts of disposal of large quantities of depleted uranium in a near-surface disposal facility.

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Transactions of the Korean Nuclear Society Autmn Meeting, PyeongChang, Korea – October 2007

Youn-Myoung Lee and Yongsoo Hwang, Korea Atomic Energy Research Institute

To demonstrate the performance of a repository, GoldSim was used to examine the dose exposure rate to people due to long-term nuclide releases from a high-level waste repository and the results are compared to that of a similar model built in AMBER. The GoldSim model integrates the results of complex nuclide transport models through engineered barriers and geological fractured rock media surrounding an HLW repository site for a consecutive transport through a biosphere.

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Proceedings of the 11th International Conference on Environmental Remediation and Radioactive Waste Management (ICEM) – September 2007

R. Kahnt and T. Metschies

Uranium mining and milling continuing from the early 1960s until 1990 close to the town of Seelingstädt in Eastern Germany resulted in 4 large tailings impoundments. Leakage from these tailings impoundments enters the underlying aquifers and is discharged into surface water streams. High concentration of salts, uranium and several heavy metals are released from the tailings. A compartment model representing the tailings impoundments and the surrounding aquifers for the calculation of contaminant release and transport was set up using GoldSim. This compartment model describes the time dependent hydraulic conditions within the tailings and the surrounding aquifers taking into account hydraulic and geotechnical processes influencing the hydraulic properties of the tailings material. A simple geochemical approach taking into account sorption processes as well as retardation by applying a kd-approach was also implemented. The model was used to predict the effect of various remediation scenarios in a fast and traceable way.

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Czechoslovak Journal of Physics, Volume 56, D623-D628 – December 2006

D. Vopálka, Czech Technical University in Prague; D. Lukin and A. Vokál, Nuclear Research Institute Rez

This paper describes GoldSim modeling techniques for several different processes that occur in a deep geologic repository for the storage of nuclear waste.

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Conference Proceedings, WM'05 Conference, Tucson, AZ. – March 2005

B. Haverkamp, E. Biurrun, with DBE TECHNOLOGY GmbH, and M. Kucerka with Radioactive Waste Repository Authority, Czech Republic

The Richard Repository, situated at the outskirts of Litoměřice in the North of Czech Republic, has served as a repository for low and intermediate level institutional radioactive waste since the mid nineteen-sixties. Up to now, some 25,000 waste packages and thereby a significant activity of about 1015 Bq have been disposed of. Richard, originally a limestone mine excavated into a hill close to the Elbe River, was later used for military production leaving a number of wellconditioned underground cavities.In order to quantify the radiological consequences of the changed closure concept, the 2002 SA has been adapted to acknowledge the differences in the source term resulting from the changed technical concept. Also the previously deterministic model has been exchanged by a computer model that also allows probabilistic calculations using the GoldSim

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Proceedings of the NUCEF2005 Symposium – February 2005

Osvaldo Pensado and Sitakanta Mohanty, Southwest Research Institute; Takeshi Kanno and Yoshikatsu Tochigi, Ishikawajima-Harima Heavy Industries Co., Ltd.

This paper and website describes a project to build a GoldSim model for a hypothetical high-level waste repository in Japan.

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Los Alamos Science, Number 29, pgs. 56-69 – January 2005

Greg Valentine, Los Alamos National Laboratory

This article describes the process of volcanological risk assessment, including describing how this is modeled, using GoldSim, within the Yucca Mountain Total System Performance Assessment.

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Wired Magazine – November 2004

David Ewing Duncan

This Wired Magazine article provides a general overview of the Yucca Mountain project including a discussion of how GoldSim is used to try quantify the performance of the repository into the distant future.

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Proceedings of the 2003 Waste Management Symposium – February 2003

Jhon Carilli, U. S. Department of Energy, National Nuclear Security Administration Nevada Site Office. Bruce Crowe, Los Alamos National Laboratory; Paul Black, John Tauxe, Tom Stockton, and Kate Catlett, Neptune and Company; Vefa Yucel, Bechtel Nevada

This paper describes performance assessment activity for low-level waste facilities at the Nevada Test Site.

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Proceedings of the 2002 Materials Research Society Fall Meeting – October 2002

David Esh, Anna Bradford, Kristina Banovac, and Jennifer Davis, US Nuclear Regulatory Commission

This paper discusses a performance assessment model of closure of a radioactive waste tank developed by the Nuclear Regulatory Commission, using GoldSim, to independently verify results from a Department of Energy assessment of the same project.

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Proceedings of the American Geophysical Union, Spring Meeting – May 2002

Los Alamos National Laboratory

This paper describes a GoldSim model developed to assist in characterizing, monitoring and possible remediation activities for an ecosystem contaminated by outfalls from high explosive production sites at the Los Alamos National Laboratory.

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