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842 records · Page 47
All sourcesNASA NTRSDOE OSTI
DOE OSTI2015

OECD NEA radioactive waste repository metadata management (RepMet) initiative (2014-2018) - 15614

The OECD/NEA Radioactive Waste Repository Metadata Management (RepMet) initiative aims to bring about a better understanding of the identification and administration of metadata - a key aspect of data management - to support national programmes in managing their radioactive waste repository data, information and records in a way that is both harmonised internationally and suitable for long-term management and use. At this point in the project, the main focus lies on 'waste packages at their storage sites ready for geological disposal' but excluding spent fuel and high level waste (HLW). Later work will deal with metadata collected on spent fuel and HLW as well as with different phases of repository development: design and construction, and operation. In order to develop metadata, RepMet members have provided lists of data items they currently collect and manage for packaged waste. The lists, albeit it non comprehensive, suggest that the number and type of data items varies importantly from organisation to organisation. At term, RepMet plans to generate a comprehensive list of such data items and their metadata. In parallel, RepMet is developing a document which examines a selected number of existing metadata standards. Because of the specialist nature of radioactive waste management, including waste processing facilities, disposal facilities and waste packages, existing metadata standards do not seem to be transferable as defined. Rather, RepMet will explore such standards to identify relevant principles for possible adaptation to the radioactive waste management community. (authors)

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DOE OSTI2016

Chute Silo ILW Project Berkeley - 16649

Magnox, a Tier 1 Site Licensed Company (SLC), is the management and operations contractor responsible for the decommissioning of twelve of the Nuclear Decommissioning Authority's (NDA) nuclear sites in the UK. Aquila Nuclear Engineering is a specialist Tier 3, turnkey engineering company based in the UK, delivering mission critical engineering solutions to Europe's nuclear and nuclear medicine industries. Berkeley Nuclear Power Station, Berkeley, England started generating electricity in 1962, ceasing operation 27 years later in 1989. The Chute Silo ILW Project at this Reactor Site had been set up to retrieve irradiated control rods and charge chutes disposed of within a subterranean vault (silo). The project involved in-silo size reduction of waste in to 30-35 waste baskets. The waste basket was then to be retrieved via a pintle grab and hoist mechanism in to a Transfer Flask (through a silo and a Transfer Flask gamma gate). The Transfer Flask was then to transit along existing crane rails, out of the silo building and over the top of an Import/Export Facility. A Ductile Cast Iron Container (DCIC) was to be imported into Import/Export Facility and inspected/prepared to receipt the waste basket from the Transfer Flask. Once filled, the DCIC was then to be sealed and exported to an on-site storage facility. Due to an issue with the Magnox Tier 2 Framework holder in delivering a cost effective and viable solution for their Chute Silo ILW Retrieval Project, Magnox took the ground breaking decision to 'self-perform'. This involved dividing the larger project into several smaller packages. Two of these packages - for the shielded Transfer Flask and the Import/Export facility - were put out for competitive tendering directly to the Tier 3 Supply Chain. The work completed by the Tier 2 Company was shared with the Tier 3's, but Magnox expressly requested the Tier 2 proposals were scrutinised and that far more cost effective, robust and simpler solutions were provided for within the Tier 3 Tenders. Aquila won both work packages and delivered them with significant and demonstrable cost savings, on time and under budget. This was achieved by the collaborative arrangements between Aquila and Magnox, the methodologies of both company's project teams and the innovation and 'fitness for purpose' of Aquila's design pragmatism. The original Tier 2 Framework holder's price to Magnox for the Chute Silo ILW Project was between UK Pounds 2-3 M. Aquila delivered the equivalent scope for under UK Pounds 1 M. Aquila's original programme was maintained despite the award of additional scope and (Magnox) delays on site. Aquila came under the original target price for each discrete phase of the project. The above was achieved because of: - the collaborative arrangements between Aquila and Magnox; - the methodologies of both company's project teams; - the design features put forward by Aquila (welcomed and adopted by Magnox). In 2014 Aquila Nuclear Engineering received formal recognition of its achievements on this project by winning an NDA Supply Chain Award for 'Best example of supplier 'going the extra mile''. Points highlighted in the award were: - improved customer focus, leading to stronger relationships - encouraging challenge and innovation - continuous suggestions for improvement - UK Pounds 1 million savings and three months programme reduction.

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DOE OSTI2018

An Industrial Perspective of Research Within the DISTINCTIVE Program - 18045

UK Engineering and Physical Sciences Research Council (EPSRC) and three industrial partners, the Nuclear Decommissioning Authority (NDA), the National Nuclear Laboratory (NNL) and Sellafield Ltd (SL) are supporting the DISTINCTIVE (Decommissioning, Immobilisation and Storage Solutions for Nuclear Waste Inventories) consortium of eleven universities to carry out research in four theme areas of importance to the UK nuclear industry: Advanced Gas-cooled Reactor (AGR), Magnox and exotic spent fuels; PuO{sub 2} and fuel residues; legacy ponds and silo wastes; and structural integrity. This paper describes the main industry challenges in each of these theme areas and some of industry led activities to address these challenges, and provides examples of where the DISTINCTIVE research output is assisting the nuclear industry in meeting these challenges. (authors)

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DOE OSTI2018

Drop Testing of a Container for the Storage, Transport and Disposal of Intermediate Level Waste - 18078

Impact tests were performed, as part of a corresponding container's substantiation, during design development of a shielded container proposed for use at Sellafield for waste retrieval from the First Generation Magnox Storage Pond (FGMSP) in the UK. The mechanical test program comprised a 9 m free drop test onto an unyielding target in a container long lid edge down orientation at ambient conditions. Further, a 0,5 m free drop test onto a punch target was performed. Here, the container was orientated with the lid downwards in a way that the punch, a mild steel bar, impacts a filter lid. The test specimen was instrumented with strain gauges and accelerometers for the drop tests. Transient strains at selected points of the inner and outer container walls, at the shielding lid, as well as at the lid bolts were measured during the container's impact. Furthermore, decelerations of the container body, container lid, and the skip were measured. The complex geometrical changes of the container due to impact were determined by optical 3d- deformation measures using the projected fringes method in combination with multi-image photogrammetry. This paper summarizes the performance of the drop tests and various drop test results in context with the design development as well as aspects regarding the associated Finite Element (FE) analyses and post-test evaluation. (authors)

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DOE OSTI2018

Systems and Tools to Facilitate Aging Management Inspections of Used Nuclear Fuel Dry Storage Systems - 18382

The Used Nuclear Fuel (UNF) dry storage systems (DSSs) are currently used at almost all the nuclear plants in the USA for the storage of their UNF as the spent fuel pools are running out of capacity to store any additional discharged fuel. Even though these DSSs are supposed to be at the reactor site for a short amount of time, they are expected to be at the reactor sites for an extended duration due to the unavailability of Interim Storage Facilities (ISF) or a permanent disposal sites like Yucca Mountain. Maintaining the integrity of the DSS canisters and storage overpacks so they can safely protect the fuel and maintain the integrity of UNF is of utmost importance during storage at reactor site ISFSI or at the ISF. Comprehensive and robust Aging Management Program (AMP) is an important aspect for DSSs to satisfy these requirements. In order to address this industry need, TN Americas have developed an enhanced NUHOMS{sup R} DSS licensed by NRC under 10 CFR Part 72 regulations and a comprehensive AMP development which includes prevention, inspection, monitoring and mitigation of any corrosion or degradation of DSS components. For DSC and HSM inspection, two remotely operating delivery systems have been developed using non-destructive examination (NDE) methods including robotic crawler and inspection ring system. This paper describes details of these developments and status of their deployment for implementation at various utility ISFSI sites. TN Americas completed the detailed design of the DSC inspection system and conducted functional tests of the inspection system on a DSC mockup and the system is ready for deployment at any NUHOMS{sup R} ISFSI site. TN Americas is committed to offer the most robust and comprehensive AMP systems, tools and services to the industry to assure the safety of the deployed DSS at the utility sites. (authors)

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DOE OSTI2018

Operational Aspects of an International Sub-seabed HLW Repository - 18450

The advantages of and the need for an internationally available repository for SNF and other HLW has been recognized since the 1980's. Various proposals have been pursued over the years but none have been able to overcome the hurdle of the Not-In-My-Backyard (NIMBY) syndrome. Sub-seabed disposal has no NIMBY concerns because the disposal facilities are located in sediments below approximately 4000 meters of international waters. This simple approach precisely emplaces HLW canisters using penetrators released from a ship and driven by gravity ∼50 meters into the sub-seabed ooze. The concept was actively studied and demonstrated by 200+ researchers from 10 different countries for over 12 years. Although it was found to be technically feasible and cost effective, social pressures to keep the oceans off-limits to most disposal activities resulted in termination of the coordinated international effort. By 1994 an International Maritime Organization (IMO) treaty, commonly referred to as the 'London Convention/ London Protocol' was in place banning all such activities. However, the list of banned activities has been amended as recently as 2006. The sub-seabed repository effort has been conducted on three fronts. First, previous research was evaluated to confirm the technical feasibility and identify areas requiring additional research or development. Secondly, the probability of successfully amending the London Convention/London Protocol was assessed. Third, an operational and business model was developed to ensure the private enterprise endeavor was worth pursuing from a business standpoint. The latter is the focus of this paper. (author)

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DOE OSTI2019

Solving Operational Challenges with INL's Integrated Waste Treatment Unit (IWTU) - 19003

In 2005, the THOR steam reforming fluidized-bed reactor technology was selected by the U.S. Department of Energy for treatment of sodium-bearing waste at the INL. The initial commissioning was typical, until June of 2012 when an over-pressurization event resulted in a significant release of solids. Recovery and subsequent testing systematically dealt with challenges associated with operation of three primary vessels: the denitration and mineralization reformer, the process gas filter, and the carbon reduction reformer. Additional challenges with the following ancillary systems surfaced during testing: the auger/grinder, sample system, and the approach to decontamination of the process vessels prior to outages. The major operational challenges covered fluidization issues, premature refractory failure, high-temperature gaseous filter element blinding, cementitious material formation in solids handling equipment, sampling reliability, and vessel decontamination. The purpose of this paper is to share the lessons learned during the extended commissioning of the Integrated Waste Treatment Unit. (authors)

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DOE OSTI2019

Development of the B-25 Low Level Radioactive Waste Container in Taiwan - 1900x

Chinshan Nuclear Power Plant will be permanently stopped its operation in the middle of 2019 and will be the first nuclear power plant stepping into the decommissioning phase in Taiwan. According to Nuclear Reactor Facilities Regulation Act, a nuclear facility must be dismantled in 25 years after being permanently ceased operation. In its decommissioning plan, the B -25 low level radioactive waste container was one of the proposed containers used for this decommissioning task. However, the B-25 waste container was not used or developed in Taiwan before. To meet this need, Institute of Nuclear Energy Research developed a new type of B-25 waste container and will apply to the authority for its usage license. This article provided the information of the low level radioactive waste containers have been approved in Taiwan and described the design specifications of the developed B-25 waste container. Besides, the numerical evaluation and test results were also included in this article. Based on the evaluation and test results, the developed B-25 waste container satisfied the requirements of the storage container and industrial package type 2. It is believed that the usage license would be granted soon after applying it to the authority. (authors)

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DOE OSTI2019

Unlocking the Vault - Accelerated Delivery Through the Application of Innovation and Collaboration - 19011

The Pile Fuel Cladding Silo (PFCS) at Sellafield was built in 1949/50 to receive and store fuel cladding from reprocessing of Windscale Pile fuel; it has been used to store this material and other waste from the UK nuclear programme ever since. The Silo is unsuitable for indefinite storage; this along with uncertainty in the make-up and condition of the inventory combine to rank the facility alongside the most hazardous in Western Europe. Sellafield Ltd, began working with its supply chain partners Bechtel Cavendish Nuclear Solutions (BCNS - a joint venture between Bechtel Inc and Cavendish Nuclear Ltd) in 2012, to execute a suite of projects to create an access route to the waste and a capability to retrieve waste from the silo for the first time ever. However, the challenge of providing this capability, while maintaining ongoing safe storage of the waste, and underpinning future performance of both the silo and the waste packages for many hundreds of years, proved to be too much for traditional Sellafield Ltd delivery models. With both cost and schedule forecasts doubling from initial estimates, a new approach was clearly required. The team recognised that success would require all of the experience and expertise of each organisation working together to a common goal. Therefore, significant effort was expended to build a collaborative team environment into which an innovative approach to both the engineering of what was provided and the delivery methods for doing it could be launched. Focussing on collaborative culture in which innovation and fit for purpose thinking were encouraged has completely rebuilt stakeholder confidence. The project is now almost complete; 17 months ahead of schedule and British Pounds 100 m less than the approved cost. (authors)

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DOE OSTI2019

Challenges of SLOWPOKE-2 HEU Irradiated Fuel Transportation from Canada to USA - 19123(2)

The SLOWPOKE-2 (Safe Low-Power Kritical Experiment) was designed by AECL (Atomic Energy of Canada Limited) in the late 1960's. The core consists of HEU (highly enriched uranium) fuel with an enrichment of 93%. The fuel cage typically has approximately 300 fuel pins assembled in a triangular pitch between the two plates. The fuel pins are made from uranium-aluminum alloy cladded with aluminum. The SLOWPOKE-2 reactor is rated at a nominal 20 kW. with varying neutron flux, maximum being 1 E12 n/cm{sup 2}/s. The mass of the fuel cage is 5.06 kg. The life of the core can be extended by adding layers of beryllium reflector. The transportation flask for the irradiated fuel is a Type B(U)F. The shipment classification is UN3328 Class 7. To date, 4 SLOWPOKE-2 reactors have been decommissioned. The fuel from all these reactors was transported to the U.S. The CNSC (Canadian Nuclear Safety Commission) joint Canada-United States guide for approval of Type B(U) and fissile material transportation packages (RD-364) satisfies the requirements stipulated in International Atomic energy Agency (IAEA) TS-R-1 1996 edition (revised) and is acceptable to the DOT (Department of Transportation) and NRC (Nuclear Regulatory Commission) for complying with U.S. code of federal regulations 10 CFR Part 71. The export license is issued by the CNSC. The transportation licence is issued by CNSC after approval from TC (Transport Canada) and also by DOT after approval from NRC. The final home of the HEU SLOWPOKE-2 irradiated fuel is in Savannah River Site of DOE (Department of Energy). The transportation licence requires that the Type B(U)F flask is structurally sound in case of a crash. The US DOT provides a CAC (Competent Authority Certificate) which describes the irradiated fuel specifications that can be transported in the designated flask. The U.S. DOT also requires a leak test certification in accordance with ANSI N14.5-2014 to verify a leakage rate not to exceed 1 E-7 std-cm{sup 3}/s. As most SLOWPOKE-2 facilities are not located on the existing approved routes for nuclear fuel transportation, a route survey needs to be performed and submitted to the NRC. The route survey report is assessed by the NRC and issues a route approval for the transportation of the fissile material. This technical paper will discuss the detailed processes required to obtain approvals in order to transport the HEU SLOWPOKE-2 irradiated fuel from Canada to U.S. based upon recent experiences of decommissioning SLOWPOKE-2 reactors in Canada. It will provide details on the requirements of various regulators in Canada and the U.S. that govern and regulate this shipment including transportation, safety and security. It will also present lessons learned from previous experiences that can be utilized for best practice on other similar projects. (authors)

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DOE OSTI2019

Contamination Control: Challenges and Innovative Design Solutions utilized at Chalk River Laboratories - 19263

CNL has operated research reactors at the Chalk River Laboratories (CRL) site since 1947, generating a variety of spent nuclear fuel wastes produced by irradiating metallic uranium and other prototype fuels. This legacy waste has been stored in below-grade, vertical cylindrical steel and concrete structures known as Tile Holes. Ongoing monitoring of the legacy waste has identified moisture resulting from incomplete drying prior to emplacement, surface water and humidity. The undesirable storage conditions result in corrosion of both the legacy waste and the storage containers. Continued storage in these conditions may result in further degradation of the storage container and contamination of the surrounding environment. In 2004, the Fuel Packaging and Storage (FPS) Project was initiated, with the objective to develop a complete system to safely retrieve legacy waste from these Tile Holes as well as provide a stable storage environment until a final long-term management plan is established. Contamination control during retrieval, transfer and repackaging operations is critical for personnel and environmental safety. The significant challenges with retrieval of the legacy waste from the Tile Holes includes management of loose collateral liquid and solids that will be brought into the system, with the retrieved waste container. During the retrieval, transfer and repackaging operation, the challenge was to: 1) Prevent an environmental release by potentially transferring these contaminants onto the external surface of the Tile Hole Array; 2) Prevent an environmental release and ensure personnel safety while transporting the legacy waste; 3) Control release of contaminants into the new clean storage container while preventing contamination of the packaging equipment. To address the first source of contamination, a debris guide liner capable of interfacing with multiple Tile Hole configurations was integrated within the Retrieval Flask to limit contamination of the flask interior and to direct collateral liquids and solids back into the Tile Hole. The system uses a multi-function sealed Shield Gate and Drip Tray to retain and prevent the contaminants from escaping while transferring the legacy waste. This gate, along with a thin walled, Disposable Debris Guide Liner (DDGL) is an innovative solution developed to control the flow characteristics of the residual waste and to contain the waste to protect the internal components of the repackaging equipment. The development of the complete solution was further challenged as the DDGL must not tear or rip and must compact inside the new storage containers for a range of legacy waste storage containers. (authors)

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DOE OSTI2019

Career Development through Discreet Simulation Modeling - 19009

The cleanup mission of the Department of Energy (DOE) Office of River Protection (ORP) at the Hanford Site is to immobilize 212,000 m3 (56 million gallons) of nuclear waste, currently stored in 177 underground tanks, at the Waste Treatment and Immobilization Plant (WTP) and associated supplemental treatment facilities. Waste transfers to and from the WTP utilize the intricate Hanford Waste Feed Delivery (WFD) system, a network composed of: double-shell tanks (DSTs), single shell tanks (SSTs), the effluent treatment facility (ETF), a large number of pumps, valves, and leak detectors, and thousands of feet of underground transfer lines. This equipment must be prepared to safely and reliably transfer waste to the WTP. This study used discrete event simulation modeling to explore the behavior of the waste transfer system to identify areas of improvement. Two models and their subsequent results are presented: the Effluent Treatment Facility and the next-to-be-retrieved single-shell tanks (A/AX Farms). This study focused on identifying throughput bottlenecks, operational constraints, choke-point analysis, and redundancy in equipment, process design, and operational strategy. Analysis performed on the ETF OR Model indicated that the existing facility operation strategy will not result in a sufficient throughput to prevent WTP melter idling. Furthermore, in the absence of equipment failures, the facility was still shown to be unable to reach the required throughput to prevent melter idling. It is concluded that ETF system maintenance events are currently the main bottlenecks in the ETF facility. Analysis performed on the SST (A/AX) OR model indicate that the main drivers of the retrieval schedule are the hard retrieval start dates for each SST tank. In addition, it was concluded that operating the ventilation trains in parallel results in 15 times less retrieval interruptions and shortens the retrieval durations. (authors)

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DOE OSTI2014

Waste Management Analyses for Spent Structures at SNS - Paper 106

The Spallation Neutron Source (SNS) in Oak Ridge, Tennessee, is an accelerator driven neutron scattering facility for materials research. Presently, the SNS operates at 1.2 megawatt (MW) proton beam power incident on a mercury target with a proton beam energy of 1 GeV and 60 Hz repetition rate. The SNS consists of an accelerator facility, target facility, and a world-class suite of neutron scattering instruments supporting material, life-science and fundamental physics research. According to the SNS operations plan, some components are replaced when they reach their end-of-life due to radiation induced material damage or burn-up, or because of mechanical failure. During operation, these components, especially those in proximity to the target, are exposed to a radiation environment and build up significant activity during their service lifetime. All these components must be safely removed, placed in a container/package for storage, and ultimately transported offsite for disposal. An accurate estimate of the radionuclide inventory is performed assuming realistic irradiation history and decay time in order to classify a spent component. On the basis of a calculated radionuclide inventory, the spent component is classified, and an appropriate cask/package for transport and storage is suggested. After the choice for the container is made, radiation transport calculations are performed for the facility component placed inside the container, to ensure that the container is compliant with waste management regulations. When necessary, additional shielding is added. For each spent component before it goes out of the SNS site, supporting documentation is produced with a radionuclide inventory prediction, dose rate analyses and, if required, additional shielding. A dose rate analyses for the exposure prediction of personnel during components change out are performed as well. Most of the effort is concentrated on the target facility components such as target, proton beam window (PBW) and core vessel insert (CVI) plugs because of severe radiation conditions. Additionally, analyses are performed for the accelerator facility components, which are removed from the facility. Activation analyses and residual dose rates analyses are performed to support safe handling of SNS spent components at the SNS site and during transport to the waste disposal site. On the basis of the calculated radionuclide inventories, spent components characterized and classified with respect to waste management guidelines, and activity-based determinations are made regarding appropriate packaging for transport. (authors)

61 RADIATION PROTECTION AND DOSIMETRY↗
DOE OSTI2015

MONK10: Burnup credit capability - 14596

MONK{sup R} is a Monte Carlo code for nuclear criticality and reactor physics analyses. It has a proven track record of application to the whole of the nuclear fuel cycle and is well established in the UK criticality community. Furthermore it is increasingly being used for reactor physics analysis (as described at ICNC 2011), which makes it an ideal tool for burn-up credit (BUC) calculations. Throughout the paper, example calculations based on a PWR are presented to illustrate the capabilities of the MONK10 code. In order to account for the spatial dependence of material burn-up it has in the past been necessary to design models with multiple regions and materials specifically to allow material burn-up to vary spatially. This is very labour intensive and difficult to change at a later stage. A new code version, MONK10, was released last year which includes the facility to allow a burn-up (BU) mesh to be superimposed on an existing model in order to account for the spatial dependence of the burn-up. This facility is used to consider the effect of radial position of a fuel element in a PWR core on BUC. Additionally, a thermal hydraulics (TH) mesh can be used to specify region dependent temperature. This, coupled with the fact that MONK10 also incorporates an on-the-fly Doppler broadening methodology facilitates the modelling of spatially dependent temperatures for the different components. A TH mesh is used to superimpose a temperature profile on a PWR based model and the effect of this on BUC is considered. The burn-up modelling in MONK has been benchmarked against the ANSWERS WIMS deterministic reactor physics code. Once the burn-up calculation has been completed and the depleted fuel compositions determined the spent fuel compositions can be transferred into a model of a storage facility or transport flask in order to perform burn-up credit analysis. The initial model is usually described as the donor model and the latter model as the receiver model. This transfer is carried out using the COWL option which allows the specification of a material in the receiver model based on the material's composition in a given BU mesh cell from the donor model. This allows compositions and densities to be transferred and also allows user specified adjustments to be made. For example, this could include omitting the fission products in order to estimate their contribution to burn-up credit and provide an actinide-only analysis. The effect of excluding appropriate nuclides is presented. An example of how the ANSWERS SPRUCE code can be used to quantify uncertainty in a BUC calculation is also presented. (authors)

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