Potential effects of recent transportation accident on transportation of radioactive materials in USA

Abstract

In 2007, two severe transportation accidents, involving primarily long haul tractor trailers, occurred in the State of California. In the first, which occurred in Oakland in what is commonly known as the 'MacArthur Maze' section of Interstate 580 (I-580), a tractor trailer carrying gasoline impacted an overpass support column and burst into flames. The subsequent fire burned for over 2 h and led to the collapse of the overpass due to the loss of strength in the structural steel that supported the overpass. The second incident was a chain reaction accident involving several tractor trailers in the I-5 'Newhall Pass' truck bypass tunnel in Santa Clarita. This accident also involved an intense fire that damaged the tunnel and required the closing of the tunnel for repairs to the concrete walls. The US Nuclear Regulatory Commission (NRC) is studying both these accidents to examine any potential regulatory implications related to the safe transport of radioactive materials including spent nuclear fuel in the United States. This paper will discuss the details of the MacArthur Maze fire investigation. The NRC's investigation of the Newhall Pass fire is ongoing and the results are not available for publication.     

International Working Group for Sabotage Concerns of Transport and Storage Casks

Abstract

The International Working Group for Sabotage Concerns of Transport and Storage Casks (IWGSTSC), gathers multiple organisations from different countries (for US party Department of Energy, Nuclear Regulatory Commission, and Sandia National Laboratories; for German party Gesellschaft für Anlagen- und Reaktorsicherheit and Fraunhofer Institut; for the French party Institut de Radioprotection et de Sûreté Nucléaire). The goal of the IWGSTSC is to continue cooperation to improve the analytic capabilities, through information sharing and collaborative research and development plus modelling, to understand the potential adverse public health effects and environmental impacts of radiological sabotage directed at or associated with the transport and storage of civilian nuclear material or other civilian radioactive materials. The Parties may also undertake collaborative research and development in other areas of the physical protection of civilian nuclear materials or other radioactive materials. Since 2000, the IWGSTSC has conducted an extensive test programme for the assessment of the aerosol source term produced in the case of spent fuel transport sabotage by a high energy density device, after having examined several scenarios. The major goal of this programme is to produce an accurate estimate of the so called spent fuel ratio in the domain of respirable, aerosol particles produced. All the reports prepared by Sandia National Laboratories have precisely emphasised the important efforts they have made from the beginning and the amount of work already accomplished. In parallel, the International Atomic Energy Agency (IAEA), assisted by technical experts from different countries, has provided a draft document promised to become guidance for the security of radioactive or nuclear materials during transport. The IAEA document contains general guidance addressed to anyone who intends to implement or improve the security of material transports, but the text is, as of today, limited to rather general recommendations. Based on all the knowledge accumulated from past experiments and also based on the work carried out in Vienna at the IAEA, the IWGSTSC members have decided to work on the development of a method for the evaluation of the vulnerability and the source term. So for doing that, joint projects for the research, development, testing and evaluation of the consequences of the malevolent actions during transport are being pursued and are described in this paper.     

Transport of large nuclear power plant components: experiences in mechanical design assessment

Abstract

In the course of decommissioning of power plants in Germany large nuclear components (steam generator, reactor pressure vessel) must be transported over public traffic routes to interim storage facilities, where they are dismantled or stored temporarily. Since it concerns surface contaminated objects or low specific activity materials, a safety evaluation considering the IAEA transport regulations mainly for industrial packages (type IP-2) is necessary. For these types of industrial packages the requirements from normal transport conditions are to be covered for the mechanical proof. For example, a free drop of the package from a defined height, in dependence of its mass, onto an unyielding target, and a stacking test are required. Since physical drop tests are impossible generally due to the singularity of such 'packages', a calculation has to be performed, preferably by a complex numerical analysis. The assessment of the loads takes place on the basis of local stress distributions, also with consideration of radiation induced brittleness of the material and with consideration of recent scientific investigation results. Large nuclear components have typically been transported in an unpackaged manner, so that the external shell of the component provides the packaging wall. The investigation must consider the entire component including all penetration areas such as manholes or nozzles. According to the present IAEA regulations the drop position is to be examined, which causes the maximum damage to the package. In the case of a transport under special arrangement a drop only in an attitude representing the usual handling position (administratively controlled) is necessary. If dose rate values of the package are higher than maximum allowable values for a public transport, then it is necessary that additional shielding construction units are attached to the large component.     

Simplified GIS based methodology to quantify risk factors for alternative route evaluation for transport of radioactive materials

Abstract

The risk associated with the transport of radioactive materials can be impacted by many factors of the transport system, as well as by the area through which the materials may travel. Informed decision making requires a quantitative evaluation of pertinent information or conditions. Geographic information systems are often used to display spatial information. The authors have developed a simplified methodology that can be used to quantify the conditions that impact risk over a segment of a transport route. The methodology aggregates the impact of a condition based on the magnitude of the impacting condition and its location with respect to the transport corridor. This paper is a proof-of-concept demonstration for the methodology for the factors of the population in the vicinity of the roadway and the highway design criteria with respect to access ramps and medians. The methodology is particularly suited to a comparison of alternative routes for decision making, where an easily implemented methodology is needed to narrow down multiple alternatives to those few requiring a more detailed analysis.     

Development of Chinese database on safe transport of radioactive materials

Abstract

The paper introduces the newly established Chinese database, which is still in its initial stage of development, on the safe transport of radioactive materials in China. The database will collect data on several transport routes in China that presently have comparatively large transport volume. The database mainly includes data on transport management, transport incidents/accidents and road circumstances, etc. This will provide a data shared plane for departments in charge of packaging and transport and for research institutes. Areas of improvements in the future work are also mentioned at the end of the paper.     

Scale model impact limiter in type assessment of radioactive material transport packages

Abstract

In Germany, the Federal Institute for Materials Research and Testing (BAM) is the competent authority for the mechanical and thermal design safety assessment of transport packages for radioactive material according to IAEA regulations. The combination of experimental and numerical safety proof forms the basis for a state of the art evaluation concept. Reduced scale models are often used in experimental investigation for design assessment of transport packages corresponding to IAEA regulations. This approach is limited by the fact that a reduced scale model cask can show different behaviours from a full scale cask. The paper focuses on the peculiarities of wood filled impact limiter of reduced scale models. General comments on drop testing with reduced scale models are given, and the relevant paragraphs of the IAEA regulations and Advisory Material are analysed. Possible factors likely to influence the energy absorbing capacity of wood filled impact limiting devices are identified on the basis of similarity mechanics. Among possible significant influence factors on the applicability of small scale models are strain rate and size effects, failure mechanisms, underground compliance, gravitational and friction effects. While it was possible to derive quantitative estimations for the influence of strain rate, size effects and target compliance, it was not possible to evaluate the influence of compression mechanisms and gravitation. In general, if reduced scale models are used in proof of safety, uncertainties increase in comparison with full scale models. Additional safety factors to exclusively cover the uncertainties of reduced scale model testing have to be demanded. The possible application of reduced scale models in regard to crucial aspects for proof of safety has to be analysed critically.     

Comparison of collective dose in India and USA owing to transport of radioactive material by road

Abstract

This paper estimates probable collective doses owing to transport of radioactive material by road mode in India and the USA for an identical hypothetical case under respective transport conditions for the two countries, using the INTERTRAN2 computer code. The differences observed in the transport conditions in the two countries are reflected in the DNORM input parameters for the incident free transport conditions of transport and the accident rates. Owing to differences in the parameter values, it is found that the estimated probable collective dose values owing to transport of radioactive material by road mode for India are much higher than those for USA. Sensitive parameters are identified which contribute maximum to the estimated probable collective dose.     

IRSN's experience feedback list for assessment of transport package design safety reports

Abstract

Since 1996, the Institute for Radiation Protection and Nuclear Safety (IRSN), the technical support organisation of the French Competent Authority for the safety of transport of radioactive materials, has recorded the list of the difficulties most frequently encountered during the assessment of the safety reports of package designs. This experience feedback list takes into account the most recent evolutions of the regulations and the latest technological knowledge. For instance the safety reports should include the analysis of the most unfavourable configurations such as the 1 m free drop onto the bar when the package is in oblique position, the 9 m drop test of a package with slapdown, the thermal dissipation under a tarpaulin or canopies, the brittle fracture analysis at –40°C. IRSN's experience feedback list for transport package designs, which is published annually, is used as a guide by applicants to improve their package design safety reports and by IRSN for their assessments. Recently, it has been integrated in the French transport applicant guide and in the European technical guide for drafting the package design safety reports.     

Some aspects on harmonization between IAEA 'Regulations for the safe transport of radioactive material' and UN 'Recommendations on the transport of dangerous goods'

Abstract

Since 2001, the IAEA 'Regulations for the safe transport of radioactive material' are directly implemented into the UN 'Recommendations on the transport of dangerous goods', Model Regulations (the so called 'Orange Book') as class 7: radioactive material. At the same time, consistent with the time schedule of the United Nations Sub-Committee of Experts on the Transport of Dangerous Goods and the relevant international modal organisations, a regular review process of the IAEA Transport Regulations intended to issue a revised or amended edition, as necessary, every two years, was established. The last published version, the fourteenth revised edition of the 'Orange Book', includes the IAEA Transport Regulations, 2005 edition. However, the IAEA had decided not to publish a 2007 edition of the Transport Regulations, and as a consequence, did not recommend to the UN to implement the changes which had been adopted in the IAEA review cycle 2004–2005. In the last two years, further efforts have been made for better harmonisation between both documents. The harmonisation and assimilation with the UN Model Regulations concerning the transport of all nine classes of dangerous goods brings the class 7 'radioactive material' in line with the other classes for a worldwide implementation into the national and international modal regulations. The paper will discuss the benefits as well as some problems of this harmonisation process. The option to publish the 2009 edition of the IAEA Transport Regulations with the changes from the review revision cycle 2004–2005 and the harmonisation changes with the UN is considered to be important to keep the leading role of the IAEA in the further development of all aspects concerning the safe transport of radioactive material based on their competence in radiation protection.     

Thermal analysis of a storage cask for 24 spent PWR fuel assemblies

Abstract

The purpose of this paper is to perform a thermal analysis of a spent fuel storage cask in order to predict the maximum concrete and fuel cladding temperatures. Thermal analyses have been carried out for a storage cask under normal, off-normal and accident conditions. The environmental temperature is assumed to be 27°C under the normal condition. The off-normal condition has an environmental temperature of 40°C. An additional off-normal condition is considered as a partial blockage of the air inlet ducts. Four of the eight inlet ducts are assumed to be completely blocked. The accident condition is defined as a 100% blockage of air inlet ducts. The storage cask is designed to store 24 PWR spent fuel assemblies with a burn-up of 55,000 MWD/MTU and a cooling time of 7 years. The decay heat load from the 24 PWR assemblies is 25.2 kW. Thermal analyses of the ventilation system have been carried out for the determination of the optimum duct size and shape. The finite-volume computational fluid dynamics code FLUENT was used for the thermal analysis. From the results of the analysis, the maximum temperatures of the fuel rod and concrete overpack were lower than the allowable values under the normal, off-normal and accident conditions.