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At least 91 records · Page 5
All sourcesNASA NTRSDOE OSTI
DOE OSTI2014

Dosimetric comparison of flattened and unflattened beams for stereotactic ablative radiotherapy of stage I non-small cell lung cancer

Purpose: To compare contribution and accuracy of delivery for two flattening filter free (FFF) beams of the nominal energy 6 and 10 MV and a 6 MV flattened beam for early stage lung cancer. Methods: For each of 11 patients with stage I nonsmall cell lung cancer three volumetric modulated arc therapy plans were prepared utilizing a 6 MV flattened photon beam (X6FF) and two nonflattened beams of nominal energy 6 and 10 MV (X6FFF, X10FFF). Optimization constraints were set to produce dose distributions that meet the criteria of the RTOG-0915 protocol. The radiation schedule used for plan comparison in all patients was 50 Gy in five fractions. Dosimetric parameters of planning target volume (PTV) and organs-at-risk and delivery times were assessed and compared. All plans were subject to verification using Delta{sup 4} unit (Scandidos, Sweden) and absolutely calibrated gafchromic films in a thorax phantom. Results: All plans had a qualitatively comparable outcome. Obtained dose distributions were conformal (CI < 1.17) and exhibited a steep dose fall-off outside the PTV. The ratio of monitor units for FFF versus FF plans in the authors' study ranged from 0.95 to 1.21 and from 0.93 to 1.25 for X6FFF/X6FF and X10FFF/X6FF comparisons, respectively. The ratio systematically increased with increasing size of the PTV (up to +25% for 150 cm{sup 3} PTV). Yet the integral dose to healthy tissue did not follow this trend. Comparison of cumulative dose volume histograms for a patient's body showed that X6FFF plans exhibit improved conformity and reduced the volume of tissue that received more than 50% of the prescription dose. Parameters related to dose gradient showed statistically significant improvement. CI{sub 50%}, CI{sub 60%}, CI{sub 80%}, and CI{sub 100%} were on average reduced by 4.6% (p < 0.001), 4.6% (p = 0.002), 3.1% (p = 0.002), and 1.2% (p = 0.039), respectively. Gradient measure was on average reduced by 4.2% (p < 0.001). Due to dose reduction in the surrounding lung tissue, the V{sub 20} {sub Gy} and V{sub 12.5} {sub Gy} were reduced by 5.5% (p = 0.002) and 4.5% (p < 0.001). These dosimetric improvements in the fall-off were not observed for the X10FFF plans. Differences in sparing of normal tissues were not found to be statistically significant for either of the two FFF beams. Mean beam-on times were 111 s (2SD = 11 s) for X10FFF, 128 s (2SD = 19 s) for X6FFF, and X6FF plans required on average 269 s (2SD = 71 s). While the mean dose rate was 1555 ± 264 and 1368 ± 63 MU/min, for X10FFF and X6FFF, plans using the conventional X6FF were delivered with the constant maximum dose rate of 600 MU/min. Verification of all plans showed acceptable and comparable results for all plans in homogeneous as well as heterogeneous phantoms. Mean GS (3%, 2 mm) using the Delta{sup 4} phantom were 98.9% (2SD = 3.2%), 99.2% (2SD = 2.3%), and 99.2% (2SD = 2.3%) for X6FFF, X6FF, and X10FFF modalities. Verification using a thorax phantom showed GS > 98% in all cases. Conclusions: The use of FFF beams for stereotactic radiation therapy of nonsmall cell lung cancer patients yielded dose distributions qualitatively comparable to flattened beams and significantly reduced treatment delivery time. Utilizing the X6FFF beam improved conformity of dose distribution. On the other hand, X10FFF beam offered a slight improvement in treatment efficiency, and lower skin and peripheral dose. All effects were relatively small.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2014

SU-E-J-240: The Impact On Clinical Dose-Distributions When Using MR-Images Registered with Stereotactic CT-Images in Gamma Knife Radiosurgery

Purpose: Most Gamma knife treatments are based solely on MR-images. However, for fractionated treatments and to implement TPS dose calculations that require electron densities, CT image data is essential. The purpose of this work is to assess the dosimetric effects of using MR-images registered with stereotactic CT-images in Gamma knife treatments. Methods: Twelve patients treated for vestibular schwannoma with Gamma Knife Perfexion (Elekta Instruments, Sweden) were selected for this study. The prescribed doses (12 Gy to periphery) were delivered based on the conventional approach of using stereotactic MR-images only. These plans were imported into stereotactic CT-images (by registering MR-images with stereotactic CT-images using the Leksell gamma plan registration software). The dose plans, for each patient, are identical in both cases except for potential rotations and translations resulting from the registration. The impact of the registrations was assessed by an algorithm written in Matlab. The algorithm compares the dose-distributions voxel-by-voxel between the two plans, calculates the full dose coverage of the target (treated in the conventional approach) achieved by the CT-based plan, and calculates the minimum dose delivered to the target (treated in the conventional approach) achieved by the CT-based plan. Results: The mean dose difference between the plans was 0.2 Gy to 0.4 Gy (max 4.5 Gy) whereas between 89% and 97% of the target (treated in the conventional approach) received the prescribed dose, by the CT-plan. The minimum dose to the target (treated in the conventional approach) given by the CT-based plan was between 7.9 Gy and 10.7 Gy (compared to 12 Gy in the conventional treatment). Conclusion: The impact of using MR-images registered with stereotactic CT-images has successfully been compared to conventionally delivered dose plans showing significant differences between the two. Although CTimages have been implemented clinically; the effect of the registration has not been fully investigated.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2015

SU-E-J-73: Extension of a Clinical OIS/EMR/R&V System to Deliver Safe and Efficient Adaptive Plan-Of-The-Day Treatments Using a Fully Customizable Plan-Library-Based Workflow

Purpose: To extend a clinical Record and Verify (R&V) system to enable a safe and fast workflow for Plan-of-the-Day (PotD) adaptive treatments based on patient-specific plan libraries. Methods: Plan libraries for PotD adaptive treatments contain for each patient several pre-treatment generated treatment plans. They may be generated for various patient anatomies or CTV-PTV margins. For each fraction, a Cone Beam CT scan is acquired to support the selection of the plan that best fits the patient’s anatomy-of-the-day. To date, there are no commercial R&V systems that support PotD delivery strategies. Consequently, the clinical workflow requires many manual interventions. Moreover, multiple scheduled plans have a high risk of excessive dose delivery. In this work we extended a commercial R&V system (MOSAIQ) to support PotD workflows using IQ-scripting. The PotD workflow was designed after extensive risk analysis of the manual procedure, and all identified risks were incorporated as logical checks. Results: All manual PotD activities were automated. The workflow first identifies if the patient is scheduled for PotD, then performs safety checks, and continues to treatment plan selection only if no issues were found. The user selects the plan to deliver from a list of candidate plans. After plan selection, the workflow makes the treatment fields of the selected plan available for delivery by adding them to the treatment calendar. Finally, control is returned to the R&V system to commence treatment. Additional logic was added to incorporate off-line changes such as updating the plan library. After extensive testing including treatment fraction interrupts and plan-library updates during the treatment course, the workflow is running successfully in a clinical pilot, in which 35 patients have been treated since October 2014. Conclusion: We have extended a commercial R&V system for improved safety and efficiency in library-based adaptive strategies enabling a wide-spread implementation of those strategies. This work was in part funded by a research grant of Elekta AB, Stockholm, Sweden.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2015

SU-E-J-202: Performance of the Patient QA Systems in a Hybrid MRI-Linac

Purpose: The first clinical MR-linac will soon become operational, therefore patient plan QA procedures and equipment have to become MRcompatible. Reference dosimetry is affected by the magnetic field, however, relative dosimetry using patient QA systems haven’t been investigated extensively. The purpose of this study was to examine the performance characteristics of the MR-compatible ArcCHECK and Delta4 systems in a transverse 1.5 T magnetic field. Methods: Recently MR-compatible versions of both ArcCheck (Sun Nuclear) and Delta4 (Scandidos) have been developed. To examine the performance characteristics within the magnetic field, the reproducibility, dose linearity, dose rate dependence, field size and angular dependence were evaluated on the MR-linac (8 MV FFF beam, SAD of 142 cm) and a conventional linac (Elekta, 6MV). To allow comparison of the measurements with and without magnetic field, the measurement setup for the conventional linac is adapted to mimic the setup at the MR-linac if possible (e.g. SAD, dose rate). The results from the MR-linac were benchmarked to the results from the conventional linac as being the clinical reference. Results: At the moment of writing, measurements for the Delta4 are still running. Therefore, only the results of the ArcCheck are presented in this abstract. No significant difference was observed in the reproducibility of the ArcCheck (<0.06%) between both linacs. The maximum dose response difference when measuring the dose linearity was less than 0.4% and the varying dose rate resulted in maximal dose differences of 1.0% for both linacs. Response variation for varying field sizes was <2.6% at the conventional linac, and <1.0% at the MR-linac. Angular response was similar for both linacs. Conclusion: The reproducibility, dose linearity, dose rate dependence, field size and angular dependence of the MR compatible ArcCheck were not influenced by the presence of a transverse 1.5 T magnetic field. The results for the Delta4 are about to follow. Equipment is generously provided by Sun Nuclear Corporation (Melbourne, USA) and Scandidos (Uppsala, Sweden)

60 APPLIED LIFE SCIENCES↗
DOE OSTI2015

TU-AB-303-12: Towards Inter and Intra Fraction Plan Adaptation for the MR-Linac

Purpose: To develop a new sequencer for IMRT that during treatment can account for anatomy changes provided by online and real-time MRI. This sequencer employs a novel inter and intra fraction scheme that converges to the prescribed dose without a final segment weight optimization (SWO) and enables immediate optimization and delivery of radiation adapted to the deformed anatomy. Methods: The sequencer is initially supplied with a voxel-based dose prescription and during the optimization iteratively generates segments that provide this prescribed dose. Every iteration selects the best segment for the current anatomy state, calculates the dose it will deliver, warps it back to the reference prescription grid and subtracts it from the remaining prescribed dose. This process continues until a certain percentage of dose or a number of segments has been delivered. The anatomy changes that occur during treatment require that convergence is achieved without a final SWO. This is resolved by adding the difference between the prescribed and delivered dose up to this fraction to the prescription of the subsequent fraction. This process is repeated for all fractions of the treatment. Results: Two breast cases were selected to stress test the pipeline by producing artificial inter and intra fraction anatomy deformations using a combination of incrementally applied rigid transformations. The dose convergence of the adaptive scheme over the entire treatment, relative to the prescribed dose, was on average 8.6% higher than the static plans delivered to the respective deformed anatomies and only 1.6% less than the static segment weighted plans on the static anatomy. Conclusion: This new adaptive sequencing strategy enables dose convergence without the need of SWO while adapting the plan to intermediate anatomies, which is a prerequisite for online plan adaptation. We are now testing our pipeline on prostate cases using clinical anatomy deformation data from our department. This work is financially supported by Elekta AB, Stockholm, Sweden.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2016

SU-F-J-105: Towards a Novel Treatment Planning Pipeline Delivering Pareto- Optimal Plans While Enabling Inter- and Intrafraction Plan Adaptation

Purpose: To develop a new IMRT treatment planning methodology suitable for the new generation of MR-linear accelerator machines. The pipeline is able to deliver Pareto-optimal plans and can be utilized for conventional treatments as well as for inter- and intrafraction plan adaptation based on real-time MR-data. Methods: A Pareto-optimal plan is generated using the automated multicriterial optimization approach Erasmus-iCycle. The resulting dose distribution is used as input to the second part of the pipeline, an iterative process which generates deliverable segments that target the latest anatomical state and gradually converges to the prescribed dose. This process continues until a certain percentage of the dose has been delivered. Under a conventional treatment, a Segment Weight Optimization (SWO) is then performed to ensure convergence to the prescribed dose. In the case of inter- and intrafraction adaptation, post-processing steps like SWO cannot be employed due to the changing anatomy. This is instead addressed by transferring the missing/excess dose to the input of the subsequent fraction. In this work, the resulting plans were delivered on a Delta4 phantom as a final Quality Assurance test. Results: A conventional static SWO IMRT plan was generated for two prostate cases. The sequencer faithfully reproduced the input dose for all volumes of interest. For the two cases the mean relative dose difference of the PTV between the ideal input and sequenced dose was 0.1% and −0.02% respectively. Both plans were delivered on a Delta4 phantom and passed the clinical Quality Assurance procedures by achieving 100% pass rate at a 3%/3mm gamma analysis. Conclusion: We have developed a new sequencing methodology capable of online plan adaptation. In this work, we extended the pipeline to support Pareto-optimal input and clinically validated that it can accurately achieve these ideal distributions, while its flexible design enables inter- and intrafraction plan adaptation. This research is financially supported by Elekta AB, Stockholm, Sweden.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2016

Multi-Pack Disposal Concepts for Spent Fuel (Revision 1)

At the initiation of the Used Fuel Disposition (UFD) R&D campaign, international geologic disposal programs and past work in the U.S. were surveyed to identify viable disposal concepts for crystalline, clay/shale, and salt host media. Concepts for disposal of commercial spent nuclear fuel (SNF) and high-level waste (HLW) from reprocessing are relatively advanced in countries such as Finland, France, and Sweden. The UFD work quickly showed that these international concepts are all “enclosed,” whereby waste packages are emplaced in direct or close contact with natural or engineered materials . Alternative “open” modes (emplacement tunnels are kept open after emplacement for extended ventilation) have been limited to the Yucca Mountain License Application Design. Thermal analysis showed that if “enclosed” concepts are constrained by peak package/buffer temperature, that waste package capacity is limited to 4 PWR assemblies (or 9 BWR) in all media except salt. This information motivated separate studies: 1) extend the peak temperature tolerance of backfill materials, which is ongoing; and 2) develop small canisters (up to 4-PWR size) that can be grouped in larger multi-pack units for convenience of storage, transportation, and possibly disposal (should the disposal concept permit larger packages). A recent result from the second line of investigation is the Task Order 18 report: Generic Design for Small Standardized Transportation, Aging and Disposal Canister Systems. This report identifies disposal concepts for the small canisters (4-PWR size) drawing heavily on previous work, and for the multi-pack (16-PWR or 36-BWR).

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2015

Actinide Solubility and Speciation in the WIPP [PowerPoint]

The presentation begins with the role and need for nuclear repositories (overall concept, international updates (Sweden, Finland, France, China), US approach and current status), then moves on to the WIPP TRU repository concept (design, current status--safety incidents of February 5 and 14, 2014, path forward), and finally considers the WIPP safety case: dissolved actinide concentrations (overall approach, oxidation state distribution and redox control, solubility of actinides, colloidal contribution and microbial effects). The following conclusions are set forth: (1) International programs are moving forward, but at a very slow and somewhat sporadic pace. (2) In the United States, the Salt repository concept, from the perspective of the long-term safety case, remains a viable option for nuclear waste management despite the current operational issues/concerns. (3) Current model/PA prediction (WIPP example) are built on redundant conservatisms. These conservatisms are being addressed in the ongoing and future research to fill existing data gaps--redox control of plutonium by Fe(0, II), thorium (analog) solubility studies in simulated brine, contribution of intrinsic and biocolloids to the mobile concentration, and clarification of microbial ecology and effects.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2015

Development of oxygen sensors for use in liquid metal

For generation IV reactor concepts, based on liquid metal cooling, there is a need for robust oxygen sensors which can be used in the core of the reactor since corrosion can only be kept sufficiently low by controlling the dissolved oxygen content in the liquid metal. A robust, ceramic membrane type sensor has been developed at IFE/Halden (Norway) and tested in an autoclave system at KTH (Sweden). The sensor has been tested in lead-bismuth at 550 deg. C and performed well. (authors)

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
DOE OSTI2017

Swedish Solution for Reconditioning, Transport, Interim Storage and Final Disposal of Failed Fuel - 17024

Despite today's increasingly more reliable operation of nuclear power plants, failed fuel rods exist in all Swedish plants. Managing intermediate storage and sub-sequential final disposal of such rods has been a growing problem. The Swedish system for spent fuel management uses the principle of intermediate storage of the fuel in a central intermediate storage facility (CLAB) before disposal in a final repository according to the KBS-3 method. However, the intermediate storage facility does not allow storage of failed fuel and the final repository has limitations on moisture in the deposited fuel and hence failed or broken fuel rods cannot be accepted as-is. The nuclear power companies in Sweden have jointly established the Swedish Nuclear Fuel and Waste Management Co, SKB, to manage the spent fuel and the operational waste. To find a solution to transport the failed fuel to storage, SKB has established a project with the goal to have all currently failed fuel rods from all the Swedish nuclear power plants reconditioned and transported to the intermediate storage facility before the year of 2020. The project has established the acceptance criteria for reconditioned failed fuel in the final repository and evaluated a number of options for treatment, encapsulation and transportation of the failed fuel rods. Furthermore, two suppliers have developed reconditioning methods fulfilling the criteria and contracts were signed with both suppliers in May 2016. This paper outlines the details of the Swedish solution for treatment and storage of failed fuel including the technical requirements for the reconditioning method and transportability. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2015

Radioactive waste management in France: taking-up present and future challenges - 15120

The reduction of the volume and radiotoxicity of radioactive waste has been one of the key drivers for the implementation of the French nuclear program. Interactions between the nuclear industry, the administration, the competent authorities and other stakeholders including the civil society has led to a continuous evolution of the industrial facilities, practices, solutions and products to move towards waste minimization. Bringing a solution to the management of ultimate radioactive waste is clearly a requirement for the sustainable development of nuclear energy whose crucial role in the world's future energy mix has been confirmed in the past few months by several international organizations. The first question to be answered concerns the definition of radioactive waste. This notion may be seen as self-evident. It is not. For example, used fuel is considered a High Level Waste in Finland or Sweden, but a recyclable material in countries including China, France, India, Japan, Russia, and the Netherlands. In France, a definition is provided by law to clarify this notion. Indeed, the 2006 French law concerning the Sustainable Management of Radioactive Materials and Waste stipulates that 'ultimate radioactive waste shall include any radioactive waste for which no further processing is possible under current technical and economic conditions, notably by extracting their recoverable fraction or by reducing their polluting or hazardous character'. Used fuel is thus reprocessed in order to reduce the final waste volume and long term radiotoxicity, while extracting value from the recovered materials. Even if the general approach and the processes may be common for waste management, it is important to clearly make the distinction between the wastes stemming from used fuel processing or conditioning (when considered as waste), the wastes generated through the operation of nuclear power plants and fuel cycle facilities, and the waste arising from the dismantling of nuclear installations. After a brief overview of the different types of waste stemming from nuclear power generation, this paper will review solutions and processes already implemented for their safe and efficient management. It will also practically illustrate the evolution of these processes and related facilities to further gain in efficiency, notably in terms of volume reduction; the related R and D outcomes will be addressed. It will also describe the upcoming challenges in this field and the envisioned solutions to respond to them; the efficiency, the completeness and consistency of these solutions with the currently considered global framework, based on a stepwise and long term approach from waste generation to disposal, will also be analyzed. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2015

Treatment of contaminated non-iron metals for clearance - 15361

Iron based metals and concrete make up most of the structures in a nuclear power plants and most other nuclear installations. During the last few decades, a lot of effort has been put into the treatment of steel in order to allow recycling of the metal and to reduce the volume for final disposal. In addition to the iron based metals, there are also other metals in significant amounts that can be treated for recycling and waste minimisation. Aluminium, lead, titanium, brass and copper have all been treated by Studsvik in the metals treatment facility in Sweden over the years. Some of these metals like lead and aluminium causes certain concerns (for reasons not related to their radioactivity) if they were to be disposed as radioactive waste. Other as copper and titanium has a high economic value if recycled outside the nuclear industry. Studsvik experience from treatment of non-iron metals is reported in this paper. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2015

The role of Aspo Hard Rock laboratory for the Swedish nuclear fuel and waste management's research, developing and demonstration programme for a final repository of spent nuclear fuel - 15378

The Aspo Hard Rock Laboratory (HRL), located in the Simpevarp area in the municipality of Oskarshamn in Sweden, Figure 1, constitutes an important part of the Swedish Nuclear Fuel and Waste Management (SKB) work with design and construction of a deep geological repository for final disposal of spent nuclear fuel. One of the fundamental reasons behind SKB's decision to construct an underground laboratory was to create an opportunity for research, development and demonstration in a realistic and undisturbed rock environment down to repository depth. Most of the research has concerned with processes of importance for the long-term safety of a future final repository and the capability to model the processes taking place at repository depth. Demonstration addresses the performance of the engineered barriers and practical means of constructing a repository and emplacing the canisters containing spent fuel. SKB will in the coming years more focus on using the Aspo HRL for demonstrating technology for and function of important parts of the repository system before constructing and operate the spent nuclear fuel repository in Forsmark. Aspo HRL includes both a research village with office space for 100 persons and different laboratories, e.g. Chemistry and Material Science Laboratory and Bentonite Laboratory, and an underground research laboratory to a depth of 460 m. The Aspo HRL is also open for other organisations to be used for their own projects and experiments not only related to nuclear waste management research. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2015

Separation and recovery of uranium from residues to allow disposal as VLLW - 15379

During fabrication of uranium fuel, significant amounts of uranium contaminated wastes are generated. The uranium concentration in the waste is typically 1-10% in weight. With this uranium concentration, the residues constitute long lived Low Level Waste (LL-LLW) which need to be disposed of in a repository specifically for this type of waste. Through recovery of uranium from the primary waste, the potential for reducing the concentration of uranium to such low levels that the remaining waste qualifies as Very Low Level Waste (VLLW) are significant. The remaining waste could then be disposed of in a less costly disposal than the primary waste. A method for recovery of uranium from waste has been developed and used in Sweden and includes leaching with sulphuric acid, solvent extraction and precipitation. The final result is ammonium di-uranate (ADU). The remaining waste typically has residual uranium content in the range of 100 g uranium per tonne of waste. In several countries this would permit disposal at a hazardous waste landfill site after conditional clearance. During the development process, it has been shown that for certain types of waste it's possible to reduce the uranium concentration even further. The paper gives an overview of the technology, its applications as well as advantages and limitations. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2015

Decontamination of uranium contaminated metals - 15 years of experience - 15528

Uranium contaminated waste is somewhat of a special case among radioactive waste as the uranium, if enriched, also is a valuable asset. Incineration and pyrolysis of uranium contaminated dry active waste (DAW) was covered during WM'14. Uranium contaminated metals is however somewhat different when it comes treatment and recovery of uranium. Since the late 1990's the Metals Treatment and Recycling Facility in Studsvik Sweden has treated approximately 1500 tonnes of metals contaminated by uranium. Depending on the metal, melt-decontamination may or may not be a way of salvaging metals if the pre-treatment was not enough. The only metals that currently are subject to melt decontamination are iron based materials as well as lead. Other metals such as aluminium, brass and copper must all be cleaned prior to melting. Recovery of uranium from the secondary waste is most likely economically feasible only from the first step, the pre-melting decontamination, as the slag is just that, a slag, which is molten at a high temperature, and thereafter cooled under non-controlled conditions so uranium is trapped inside in an unspecified chemical form. This paper will describes experiences and lessons learned from 15 years of treatment, including melt-decontamination, of uranium contaminated metals. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2015

Repository planning for spent nuclear fuel and high-level radioactive waste: insights from U.S.. and international programs - 15638

For decades, the United States and other nations with nuclear programs have been planning for permanent disposition of spent nuclear fuel and high-level waste, to address the increasingly difficult problem of storing these materials for the long term. These plans are complicated by issues ranging from technological factors to regulatory approaches and public concerns about health and environmental protection. In its 2012 report, the Blue Ribbon Commission (BRC) on America's Nuclear Future identified a number of recommendations for creating a safe, long-term solution to the nation's problem of managing and disposing of its spent fuel and high-level radioactive waste. These include a recommendation that the U.S. Environmental Protection Agency (EPA) revise its standards for a high-level waste repository. The EPA is currently reviewing and synthesizing literature relevant to such standards, including: (1) existing national and international standards and guidelines for repositories; and (2) benefits and barriers to such standards, including limitations related to current technologies, as well as siting, licensing, and construction processes. This paper highlights findings of this literature review and synthesis. More than 90 countries, from Albania to Vietnam and Yemen, were identified as potential sources of relevant information based on existing nuclear programs or consideration of such programs to address future energy needs. Pursuant to the BRC recommendations, the U.S. Department of Energy (DOE) has compiled extensive information resources relevant to spent fuel and radioactive waste repositories in the Centralized Used Fuel Resource and Information Exchange (CURIE) database developed by Oak Ridge National Laboratory. Further valuable sources of information include annual proceedings of recent Waste Management Symposia, which provide insights into recent trends and progress across various national and international programs. Recent literature from a number of countries, including the United States and Canada, and the United Kingdom, Finland, Sweden, France, Germany, and other countries in Western Europe, as well as other regions including Australia, indicates that consent-based siting has emerged as a dominant theme. In addition to effective siting processes, key program needs identified in the literature include regulatory standards and performance context, as well as reliable technologies and engineered systems, such as for deep drilling and assured safe containment of these radioactive materials extending into the very long term. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2015

The root causes of siting failures in nuclear waste management - 15652

For many decades, the global nuclear industry and associated governments have attempted to establish new facilities for the storage and disposal of nuclear wastes. Success has been rare (France, Sweden and Finland being the examples) and remains elusive for many programs despite attempts to change the selection process in some cases. Success has been aided by local and national consent in the few cases that are proceeding. A small study of several countries lack of success is examined to determine the dominant reasons for such failures. The goal of the study is to inform the planning process for efforts to site new facilities by feeding back some lessons learned from past failed efforts. This limited review of international experience indicates that there is no simple approach available for siting deep geologic disposal or even centralized storage facilities. A number of countries have tried multiple times to find an acceptable site. Two studies [1, 2] clearly indicate that there must be adequate assurance of social as well as technical acceptability for successfully siting such facilities. It is evident that even though the technology and science may be proven, it is the politics and public engagement in siting processes that dominate the failures. However, the detailed reasons within each effort present a richer set of lessons. This paper will summarize the findings and present them such that they can be used to inform future siting efforts by a nation. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2016

Importance of Upfront Preparatory Works for Vessel Internals Segmentation Projects - 16096

For more than thirty years, Westinghouse has been involved in reactor internals segmentation activities in the U.S. and Europe. Westinghouse completed in 2015 the segmentation of the reactor vessel and reactor vessel internals at the Jose Cabrera nuclear power plant in Spain and a similar project is on-going at Chooz A in France. Four more major reactor internals segmentation projects have been recently awarded in Sweden (Barsebaeck 1-2) and in Germany. (Philippsburg 1 and Neckarwestheim 1). For all reactor dismantling projects, it is essential that all activities are thoroughly planned and discussed upfront together with the customer. Detailed planning is crucial for achieving a successful project. One key activity in the preparation phase is the 'Segmentation and Packaging Plan' that documents the sequential steps required to segment, separate, and package each individual component, based on an activation analysis and component characterization study. Detailed procedures and specialized rigging equipment have to be developed to provide safeguards for preventing certain identified risks. The preparatory work can include some plant civil structure modifications for making the segmentation work easier and safer. Some original plant equipment is sometimes not suitable enough and need to be replaced. Before going to the site, testing and qualification are performed on full scale mock-ups in a specially designed pool for segmentation purposes. The mockup testing is an important step in order to verify the function of the equipment and minimize risk on site. This paper is describing the typical activities needed for preparing the reactor internals segmentation activities using under water mechanical cutting techniques. It will provide experiences and lessons learned that Westinghouse has collected from its recent projects and that will be applied for the new awarded projects. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗