First tests results for determination of seal life of EPDM O-rings at high temperature (determined by unique method)

Abstract

A recurrent concern in the design of packaging for the transportation of radioactive material is to determine the life of elastomeric O-rings at a high temperature. Following a precedent paper presenting the TN International method for the determination of ethylene propylene diene (EPDM) O-rings seal life, a first series of tests results have been obtained. These first results are used with the previously mentioned method to see that the EPDM seal life did follow an Arrhenius curve. This Arrhenian behaviour is verified below a certain 'threshold temperature' that seems to be the upper limit for the use of such elastomeric O-ring grades. With the 'seal life versus temperature' curve obtained from these tests results, the time–temperature profile of O-rings in casks can then be benchmarked with the seal resistance and its 'maximum permissible damage rate'.     

Test Facilities for Radioactive Material Transport Packages (Lne,Paris, France)

Abstract

Test facilities at Laboratoire National d'Essais (LNE), covering Type A, Type B and Special Form     

Test Facilities for Radioactive Material Transport Packages (LNE,Paris, France)

Abstract

This paper describes the test facilities at Laboratoire National d'Essais (LNE) for radioactive material transport packages covering IP, Type A and Type B packages.     

RADSAFE: A Transport Plan for Radioactive Materials Transport in Great Britain

Abstract

RADSAFE, the country's largest radioactive material transport plan, was implemented in Great Britain on 1 August 1999. The reasons RADSAFE was developed, the philosophy developed during the drafting of RADSAFE and the structure of RADSAFE are explained.     

Two-Dimensional Numerical Simulation of Ion Collection from Pulsed Laser Induced Plasma

Abstract

The process of ion collection from a plasma produced between parallel plates by pulsed lasers was simulated with a two-dimensional numerical code. The trajectories and velocities of ions in the electric field are calculated using Newton's equation of motion. Assuming the Boltzmann relation for electrons, the electric field is calculated by solving numerically the Poisson equation. The numerical results for the time development of the ion collection are shown to be in good agreement with experimental results.     

Risk and rationality

Abstract

'Risk communication' traditionally has often involved providing large amounts of factual data about safety, on the assumption that these data will serve to reassure people and reduce their inclination to oppose the activities of the industry in question. However, evidence that this approach is successful is sparse – often the industries that raise the safety issue most vigorously are those which provoke the most anxiety, irrespective of the level of 'objective' risk involved. This paper suggests an alternative 'rationality', psychological rather than statistical. By offering a different perspective on risk perception – that as individuals we live our lives at a fairly constant level of anxiety and look for candidates in our environment on which to 'hang' or blame this anxiety – it suggests a changed emphasis in the relationship between industry and affected individuals.     

Marine Transport of Irradiated Nuclear Fuel,Plutonium and High Level Wastes

Abstract

On 4 November 1993 the Assembly of the International Maritime Organization (IMO) adopted the Code for The Safe Carriage of Irradiated Nuclear Fuel, Plutonium, and High-level Radioactive Wastes in Flasks on board Ships. The Code was recommended for adoption by a Joint IAEA/IMO/UNEP Working Group and sets standards for the survival capability of ships carrying those materials. It aims to complement the packaging requirements and the shipment procedures imposed by the IAEA's Regulations for the Safe Transport of Radioactive Material and IMO's International Maritime Dangerous Goods Code (IMDG-Code). The Joint Working Group also considered a number of issues related to accidents at sea, accident statistics, risk studies and emergency response. The Group concluded that all the available information demonstrates very low levels of radiological risk and environmental consequences from the marine transport of radioactive material. In this paper the details of the Code and the highlights of the deliberations regarding marine transport of radioactive material are discussed.     

The 1996 Edition of the IAEA's Regulations for the Safe Transport of Radioactive Material — What's New?

Abstract

The 1996 Edition of the International Atomic Energy Agency's Regulations for the Safe Transport of Radioactive Material has been published and is being implemented by Member States and international transport organisations. Several major changes were made in the requirements, particularly those applicable to uranium hexafluoride packaging, air transport of larger quantities of material, and the specification of material which is exempt from the regulations. The international transport organisations are working toward a uniform effective implementation date of 1 January 2001. Shippers and carriers should begin preparation for compliance with the revised requirements in order to ease implementation.     

The Long Way to a New Comprehensive Edition of the IAEA Transport Regulations

Abstract

This keynote address traces the history of the IAEA Regulations for the Safe Transport of Radioactive Materials and supporting documents and highlights the key activities of the Agency. The review process for the regulations and new developments on the Agency's programme are described.     

Disposal container safety assessment – drop tests with 'Yoyushindo-Disposal' waste container onto concrete target

Abstract

This paper presents technical details of the drop test performance as well as some experimental results of tests carried out with the Japanese 'Yoyushindo-Disposal' waste container for intermediate depth disposal. The drop test program comprised three single 8 m drop tests at the specimen's corner edge orientation onto a concrete slab. The slab was connected to the unyielding IAEA target of the BAM's 200 t drop test facility. The three tested specimens had masses between 20 000 and 28 000 kg depending on their content mass. The tests were accompanied by various metrology, such as strain and deceleration measurements, optical three-dimensional deformation methods, leak tightness testing and test installation for potential particle release measurements to collect a set of data for establishing a basis for safety assessment.     

Use of Alcan's Al-B4C metal matrix composites as neutron absorber material in TN International's transportation and storage casks

Abstract

Major issues in the area of transportation and/or storage of radioactive materials are reliability and safety of engineering components. Among the functions to be undertaken, transportation and storage systems shall allow the criticality control of the transported matter, the control of its temperature, as well as the capacity to withstand the mechanical stresses due to normal, incidental and accidental conditions of use. In most cases, criticality control requires the use of an internal arrangement made of a neutron absorber material, which must also have high thermal conductivity properties to ensure the temperature control. When, as in many AREVA-TN International applications, the design takes credit of the neutron absorber material as a structural component, it must show high mechanical performance. Alcan's Al-B₄C metal matrix composites (Al-B₄C MMCs) meet all the above mentioned requirements, due to their special capability of capturing neutrons, their light weight, and their superior thermal conductivity and mechanical properties. The significant advantage of Alcan's technology is its flexibility with regards to a wide range of boron carbide contents and matrix alloys (from AA1XXX to AA6XXX). This enables the adjustment of the properties to the exact needs of the design. TN International presently uses extruded and/or rolled Al-B₄C MMC parts in several of its internal arrangements. The present paper gives an overview of the manufacture processes of Alcan's Al-B₄C MMCs, from the mixing of B₄C into liquid aluminium to the extrusion and rolling operations. It describes the methods and results for the qualification tests in terms of the neutron absorption, thermal, physical and mechanical properties of the material. Finally, details are given on the use of Alcan's MMCs as a neutron absorber with enough credit for structural material in TN International's TN24 designs.     

Three Year Experimental Study of Leaching Phenomena from Low Level Radioactive Cement-Based Waste Forms

Abstract

This study was carried out in order to demonstrate the safety of homogeneous cementbased waste forms (hereinafter called cement forms) for BWR's low level radioactive wastes as engineered barriers. Eighteen full scale simulated cement forms were manufactured with the addition of ¹³⁷Cs, ⁶⁶Co and ⁹⁰Sr.

Leaching tests on these forms were carried out for approximately three years. In order to study the relationship of leachability to environments at disposal sites, this Three Year Leaching Test was conducted for three kinds of environmental conditions, sea water, land water and soil. After the tests, all of these forms were cut to measure the distribution of the radionuclide's density within them. In case of the soil tests, the distribution of radionuclide in the soil was also measured.

The radionuclide leachability results reveal that ⁶⁰Co was almost completely retained in the cement forms and that ¹³⁷Cs leached from cement forms was mostly adsorbed by the soil. On the other hand, ⁹⁰Sr was not trapped in the forms and leaked through the soil around them in retard. This study also showed that simulated cement forms buried in the soil were more physically and chemically stable, and had longer term stable radionuclide containment capability than those which were submerged in sea or land water.     

Design and Testing of the Nupak-200 Type-B(U)F Packaging

Abstract

The design and testing of the Nupak-200 Type-B(U)F packaging developed by AEA Technology with support from the United Kingdom Atomic Energy Authority (UKAEA) is described. The design concept and operational criteria are discussed, and the packaging's principal features are reviewed. The adaptability of the two-box assembly is examined, as is its application to current and future radioactive materials transport requirements. The paper highlights the test programme that was devised to simulate the impalement of composite steel and cork panels on a punch of the type used for testing to IAEA standards. This was done in order to generate adequate data about the materials' characteristics for the finite analysis programs which supported the design. The paper concludes by reviewing the drop-test. performance of the package and compares the computer analyses with the actual test results.     

Measurements of Resonance Neutron Self Shielding Factors for Gold and Silver Using Slowing-Down Time Spectrometer

Abstract

The resonance neutron self-shielding factors for cylindrical samples of various thicknesses of gold and silver have been measured in the narrow energy groups with a lead slowing-down time spectrometer as a neutron source.

Calculation by Wigner's rational approximation gives 10–20% smaller self shielding factors than the experimental ones except for the limiting cases of sample thickness.

The collision probability theory, on the other hand, was found to give rather good agreement with the experiments in all the measured cases.     

The excepted package: consignor's friend or Pandora's Box!

Abstract

Of the 500 000 or so package movements in the UK, the majority are the humble 'excepted package'. However, for a package that is on the face of it, so benign, it causes more problems to consignors and carriers than more strictly regulated packages. As the International Atomic Energy Authority (IAEA) regulations are not that transparent, they are open to misinterpretation. When various interpretations of driver training regulations, the requirements of ADR and 'other' hazardous properties overriding the radiological hazard are taken into consideration, one can get (and often sees) a great deal of confusion. The present paper looks at the basic requirements for an excepted package. It then goes on to discuss some consignor's interpretations of the regulations, the conflict within current UK regulations and suggests that, at the very least, a code of practice is required to smooth out some of these difficulties, and calls for more clarity in the regulations.     

Passive Detection of Concealed Strontium-90 Radioisotope Thermoelectric Generators in Transport

Abstract

Many radioisotope thermoelectric generators (RTGs) used in civilian and military applications employ ⁹⁰Sr, a high-energy beta emitter. The possibility of indirect or deliberate contamination of the environment with this isotope is not negligible. Detection and identification of a concealed ⁹⁰Sr RTG is possible by monitoring the continuous-energy spectrum of the bremsstrahlung radiation emitted as the source's betaparticles interact with the active material inside the source and with the surrounding container and shielding material. This detection concept is verified by measuring the energy spectrum of the bremsstrahlung radiation emitted from a small-activity shielded ⁹⁰Sr source, using two modest energy-resolution detectors: a NaI(Tl) crystal and a BC-408 plastic scintillator. These measurements were in turn utilised to verify the results obtained from Monte Carlo simulations, to determine the detector response for a realistic RTG source. The minimum detection time was then estimated as a function of the activity of the source and thickness and type of surrounding shielding.     

COG-OP-30B: A New COGEMA Overpack for Type 30B Cylinders

Abstract

Facing the difficulties encountered in the United States of America in obtaining a durable certificate of approval for the existing overpacks, COGEMA desired to free itself from the constraints imposed by these packagings for the transport of enriched uranium hexafluoride. Transnucl6aire therefore initiated the design of a new Type B(U)F overpack, on behalf of COGEMA, for use with the 30B cylinders containing uranium hexafluoride enriched up to 6% in ²³⁵U, obtained from natural or reprocessed uranium. The external aspect of the new overpack is quite standard (two cylindrical halves closed with ten toggles) and it keeps the same stowage system so that it can be used with the methods of transport which exist already. The main features of COGEMA's overpack are a reinforced internal structure to protect the 30B cylinder's skirt from bending and better absorption of the drop energy to limit the acceleration under impact. The drop tests and a fire test were performed successfully in February and March 1997, the French Certificate of Approval was obtained at the end of 1998, the Swedish validation by mid-1999 and the Canadian validation at the beginning of 2000.     

Fundamental Experiment of Potassium Heat Exchanger Using Principle of Heat Pipe

Abstract

In order to provide compact and reliable sodium equipments including a steam generator, performance tests are conducted with a potassium heat exchanger, which is featured by the separate construction of primary and secondary coolant systems. A small amount of potassium plays a role as an intermediate media of heat transportation between these two coolant systems. Heat is transfered by evaporation and condensation of potassium on the surfaces of the primary and the secondary coolant pipings, respectively. The tests are performed in the temperature range of 200-300°C and the maximum heat transfer reaches 1.3 kW (heat transfer rate at the primary heating source: 8.6 W/cm² at 300°C). The experimental results are analyzed by using Langmuir's and Schrage's equations and close agreement between experiment and theory is obtained.     

The Application of Fracture Mechanics to The Safety Assessment of Transport Casks For Radioactive Materials

Abstract

BAM is the responsible authority in Germany for the assessment of the mechanical and thermal design safety of packages for the transport of radioactive materials. The assessment has to cover the proof of brittle fracture safety for package components made of potentially brittle materials. This paper gives a survey of the regulatory and technical requirements for such an assessment according to BAM's new 'Guidelines for the application of ductile cast iron for transport and storage casks for radioactive materials'. Based on these guidelines, higher stresses than before will be permissible, but it is necessary to put more effort into the safety assessment procedure. The fundamentals of such a proof using the methods of fracture mechanics are presented. The recommended procedure takes into account the guidelines of the IAEA's advisory material which are based on the prevention of crack initiation. Examples of BAM's research and safety assessment practices are given. Recommendations for further developments towards package designs with higher acceptable stress levels will conclude the paper.