scholarly journals Computed tomography of human joints and radioactive waste drums

Author(s):  
Harry E. Martz ◽  
G. Patrick Roberson ◽  
Karin Hollerbach ◽  
Clinton M. Logan ◽  
Elaine Ashby ◽  
...  
1990 ◽  
Vol 217 ◽  
Author(s):  
J.S. Steude ◽  
P.D. Tonner

ABSTRACTAcceptance criteria for disposal of radioactive waste drums require that the cement-solidified material in the drum contain minimal free liquid after the cement has hardened. Free liquid is to be avoided because it may corrode the drum, escape and cause environmental contamination. The DOE has requested that a nondestructive evaluation method be developed to detect free liquid in quantities in excess of 0.5% by volume. This corresponds to about 1 liter in a standard 208 liter (55 gallon) drum. In this study, the detection of volumes of free liquid in a 57 cm (2′) diameter cement-solidified drum is demonstrated using high-energy X-ray computed tomography (CT). It is shown that liquid concentrations of simulated radioactive waste inside glass tubes imbedded in cement can easily be detected, even for tubes with inner diameters less than 2 mm (0.08″). Furthermore, it is demonstrated that tubes containing water and liquid concentrations of simulated radioactive waste can be distinguished from tubes of the same size containing air. The CT images were obtained at a rate of about 6 minutes per slice on a commercially available CT system using a 9 MeV linear accelerator source.


Sensors ◽  
2021 ◽  
Vol 21 (8) ◽  
pp. 2630
Author(s):  
Luigi Cosentino ◽  
Quentin Ducasse ◽  
Martina Giuffrida ◽  
Sergio Lo Meo ◽  
Fabio Longhitano ◽  
...  

In the framework of the MICADO (Measurement and Instrumentation for Cleaning And Decommissioning Operations) European Union (EU) project, aimed at the full digitization of low- and intermediate-level radioactive waste management, a set of 32 solid state thermal neutron detectors named SiLiF has been built and characterized. MICADO encompasses a complete active and passive characterization of the radwaste drums with neutrons and gamma rays, followed by a longer-term monitoring phase. The SiLiF detectors are suitable for the monitoring of nuclear materials and can be used around radioactive waste drums possibly containing small quantities of actinides, as well as around spent fuel casks in interim storage or during transportation. Suitable polyethylene moderators can be exploited to better shape the detector response to the expected neutron spectrum, according to Monte Carlo simulations that were performed. These detectors were extensively tested with an AmBe neutron source, and the results show a quite uniform and reproducible behavior.


Author(s):  
J. A. Mason ◽  
W. Hage ◽  
R. Price ◽  
A. C. Tolchard ◽  
A. C. N. Towner

The paper describes an automated non-destructive assay (NDA) system for the measurement and characterization of radioactive waste. The Waste Characterisation System (WCS) can be adapted to measure a variety of drum sizes: 60, 220 (55 gallon) and 440 liter, the latter with a maximum weight of 1500 kg (1.5 tonnes). The NDA system includes a Tomographic Segmented Gamma Scanner (TSGS) and an active/passive neutron Differential Die-away (DDA or DDT). The system can assay a wide variety of waste types in a range of waste matrices. The assay stations are linked by a heavy duty roller conveyor which incorporates a 20 drum buffer store, a load cell (built into the conveyor), bar code readers and a dose rate measurement station. The Tomographic Segmented Gamma Scanner (TSGS) combines conventional high resolution gamma spectrometry and a tranission source to interrogate a waste drum in vertical slices (segments) as for Segmented Gamma Scanner (SGS) measurements. However, in the case of the TSGS, while the drum is rotated, it is also moved in the horizontal direction leading to an enhanced ability to correct the gamma ray energies, from the nuclides of interest, for the attenuation of the matrix. The TSGS can also be operated as a conventional SGS for the measurement of homogeneous waste drums. The DDA is a very sensitive active neutron interrogation method that uses thermalised neutrons from a pulsed source within the chamber to irradiate a waste drum. Prompt neutrons from fissile material present in the waste (e. g. 239Pu, 235U) are detected and provide a measure of the fissile content in the drum. In passive mode, the DDA determines the even Pu nuclides exhibiting significant spontaneous fission (e.g. 240Pu). Measurement accuracy depends on correction algorithms to compensate for self-shielding and matrix effects in waste drums containing hydrogenous materials. In addition, the DDA will be provided with the Fission-Fission Neutron Correlation Analysis System (FFnC) which is an absolute technique eliminating the need for matrix dependent mass calibrations, and allowing separate U and Pu determination using delayed neutron counting. The FFnC technique will be tested for the first time on the WCS. The NDA system incorporates integrated stations to determine the weight and dose rate of each drum, the former built into the conveyor the latter as part of the TSGS. Six Geiger Muller tubes measure the surface dose at three positions on the drum side, one at 1 metre from the drum and one each measuring the surface dose of the top and bottom of the drum. The assay instruments are linked to a heavy duty conveyor system onto which up to 20 waste drums can be loaded for delivery to the various measurement stations, thus permitting unattended, automated operation. Once measured, the drums remain on the conveyer in a holding system waiting to be unloaded. Automation is provided using a programmable logic controller (PLC) and associated computers. A central computer and associated software is used for data acquisition and management.


Author(s):  
F.-W. Ledebrink ◽  
P. Faber

Abstract In the period since Germany’s experimental final repository ASSE was closed in 1978, around 5000 drums of conditioned plutonium-bearing radioactive waste from mixed-oxide (MOX) fuel fabrication have accumulated in the interim storage facilities of Siemens AG’s MOX fuel fabrication plant in Hanau, Germany — formerly ALKEM GmbH, now Siemens Decommissioning Projects (Siemens DP). Another 5000 drums will arise in the course of decommissioning and dismantling the MOX plant which has now been underway for some months. Hopes that a final waste repository would soon be able to go into operation in Germany have remained unfulfilled over the last 20 years. Also, the agreements reached between Germany’s electric utilities and the Federal Government regarding the future of nuclear energy have not led to any further progress in connection with the issue of radwaste disposal. A concrete date for a final repository to start operation has still not been set. The German Federal Government estimates that a geologic repository will not be needed for at least another 30 years. Since the opening of a final storage facility is not foreseeable in the near term, Siemens is taking the necessary steps to enable radwaste to be safely stored in aboveground interim storage facilities for a prolonged period of time. Conditioning of radwaste from MOX fuel fabrication by cementing it in drums was started in 1984 in the belief — which was justified at that time — that final storage at the Konrad mine would be possible as of 1995. The quality requirements specified for the waste drums were therefore based on the Konrad acceptance criteria. The operating license for the storage facilities at Hanau at which these drums are presently in interim storage is limited to 20 years and will be expiring in 2004. The drums have not suffered any corrosion to date and, according to past experience, are not expected to do so in the future. However, permission to keep the drums in interim storage for a longer period of time in their current form would be extremely difficult to obtain as their corrosion resistance would have to be demonstrated for a further 30 years. The present goal is therefore to create a waste form suitable for interim storage which needs no maintenance over a long-term period, incorporates state-of-the-art technology and will probably not require any further treatment of the waste packages prior to emplacement in a final storage facility. At the same time, the highest possible degree of safety must be assured for the time during which the waste remains in interim storage. This goal can be attained by conditioning the drums such that they satisfy the requirements currently specified for final storage at the Konrad repository (1). In practice, this means immobilizing the cemented waste drums in concrete inside steel “Konrad Containers” (KCs). The KCs themselves and the concrete backfill represent two further barriers which not only serve as radiation shielding but also protect the drums against corrosion as well as any possible release of radioactive materials in the event of accidents occurring during interim storage. As the KCs are cuboid in shape, they can be stacked in space-saving configurations and are thus particularly suitable for interim storage. Also, due to their extremely heavy weight, theft of the waste packages can be practically ruled out. Despite the fact that the agreements with the German Federal Government have failed to bring opening of the Konrad repository within reach, it is nevertheless a good idea today to condition radwaste in a manner that renders it suitable for ultimate storage there. The agreements between the Government and the utilities are expected at least to result in a land use permit being issued for the Konrad mine before the end of 2001. At present there are no facts known that could cause the safety of this facility to be questioned. Only recently, Germany’s International Nuclear Technology Commission (ILK) confirmed Konrad’s suitability and demanded that it be placed in operation without further delay (2). Even if its operation should, in fact, be blocked by political lobbies, potential legal action or economic considerations, the alternative repository at Gorleben could possibly become operable in approximately 30 years’ time. Gorleben was planned right from the start to be able to accommodate waste packages based on the Konrad acceptance criteria. This means that any waste packages designed for storage at Konrad could likewise be handled and stored at Gorleben. The processes used by Siemens for conditioning of radwaste conform to the recommendations of the “Guidelines for the Control of radioactive Waste with negligible Heat Generation” issued by the German Federal Ministry for the Environment, Nature Conservation and Nuclear Safety (BMU) in 1989 (3).


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