CNSC research related to impactive and impulsive loading

CNSC research related to impactive and impulsive loading

Abstract of the presentation presented at:  
The University of Western Ontario
October 26, 2017

Prepared by: Neb Orbovic
Canadian Nuclear Safety Commission

Abstract

The Canadian Nuclear Safety Commission (CNSC) is Canada’s nuclear regulator. Under the Nuclear Safety and Control Act, the CNSC regulates the use of nuclear energy and materials to protect health, safety, security and the environment; to implement Canada’s international commitments on the peaceful use of nuclear energy; and to disseminate objective scientific, technical and regulatory information to the public. The CNSC’s regulation of nuclear facilities includes, uranium mining, nuclear fuel fabrication, nuclear reactors and power plants, the production and use of medical isotopes, the decommissioning and remediation of nuclear sites, and the safe management of nuclear waste.

The Engineering Design Assessment Division (EDAD) within the Directorate of Analysis and Assessment in the CNSC’s Technical Support Branch has civil, mechanical and fire specialists who perform technical assessments of licensees’ submissions (e.g., licence applications and renewals). In order to support and improve the regulatory framework and the technical assessments, EDAD specialists implement and perform research projects and participate in international activities under the International Atomic Energy Agency (IAEA) and Nuclear Energy Agency (NEA) of the Organization for Economic Co-operation and Development, as well as in the development of national and international codes and standards.

One of the specialties of EDAD engineers is the assessment of the protection of nuclear facilities under external natural and human-induced hazards. This assessment includes seismic, impact, blast and high wind loads on structures. Structural impact and blast testing and analyses have been conducted in EDAD since 2008, through participation in: the IMPACT Test Campaign at the VTT Technical Research Centre of Finland; the American Society of Mechanical Engineers (ASME) blast tests at Oregon Ballistic Laboratories; and a series of NEA impact simulation benchmarks under the IRIS project (Improving Robustness Assessment of Structures Impacted by a Large Missile at Medium Velocity).

The IMPACT Test Campaign, which began in 2006, has involved the performance of more than 200 impact tests dealing with flexural and punching behaviour of reinforced and pre-stressed concrete slabs, as well as the impact-induced vibrations. The campaign aims to establish acceptance criteria for structural missile impact design and assessment, as well as for the calibration of numerical models. The tests were designed to assess the influence of different structural features as the influence of pre-stressing and transverse reinforcement, separately and combined, as well as the influence of longitudinal reinforcement on the structural behaviour of concrete slabs under structural impact.

ASME blast tests were established under ASME and the American Concrete Institute (ACI) Joint Task Group. The tests were performed on pre-stressed concrete slabs in order to establish structural acceptance criteria for nuclear containment structures under impulsive loading. The pre-stressed concrete slabs with dimensions of 4.88 m x 4.88 m x 0.27 m were tested using different pre-stressing levels and different reinforcement ratios, which are typical for nuclear containments. The ASME and IMPACT tests results are used for the ASME and ACI code provisions update and, eventually, for the update of CNSC regulatory documents.

The NEA simulation benchmarks IRIS_2010, IRIS_2012 and IRIS_Phase III (2017) were put in place to provide technical guidance for the numerical simulations of structures impacted by deformable (soft) and undeformable (hard) missile impacts. Over 25 teams from 10 countries participated in these benchmarks. The IRIS organizing committee supported by the scientific committee, published NEA reports with technical conclusions from these benchmarks and recommendations for verification and validation of numerical simulations.
Over 20 conference and journal papers have been published by EDAD staff on the IMPACT tests, ASME blast tests and IRIS numerical simulations. They were used as an input for the IAEA Safety Report Series on Safety Aspects of Nuclear Power Plants in Human Induced External Events.

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