Cable Penetrations Research Articles

Experimental methods for studying heat transfer in cable penetrations in case of fire

An experimental technique for studying the processes of heat transfer in cable penetrations under the thermal effects of fire is proposed. To study the influence of the design of cable penetrations on cable heating processes, three most common types of penetrations were selected. New experimental data on the dependence of the temperature of the structural elements of the cable and the penetration on time have been obtained. It is shown that the conductive core of the cable is the main element involved in the propagation of heat. The presence of an air space or a material that promotes intensive heat exchange in the cable penetration design leads to an increase in its fire resistance limit. It is determined that the cable penetration with the filling of the internal space with fire-fighting foam based on polyurethane foam is most susceptible to rapid heating and loss of fire resistance. Studies have shown that when assessing the fire resistance limits of cable penetrations, it is necessary to take into account the thermophysical characteristics of cables, their number, as well as the design features of cable penetrations.

Degradation of Soft Epoxy Resin for Cable Penetrations Induced by Simulated Severe Accidents

To obtain the knowledge that contributes to the safer operation of nuclear power plants and their prompt recovery and termination in the event of an accident, soft epoxy resins with rubber-based additives—used as insulators and airtight sealants in electrical penetrations in nuclear power plants—were aged under several simulated severe accident environments with different conditions of heat, gamma rays, and exposure to superheated steam containing no oxygen. Then, changes in structural, dynamic mechanical, mechanical, and dielectric properties were examined. It has been found that this resin becomes hard as a result of cross-linking if aged by irradiation with gamma rays. Since the cross-linking slows down the molecular motions, the glass transition temperature increases, whereas the dielectric permittivity and the dielectric loss factor decrease unless the steam penetrates the sample. Although the sample melts and disappears if directly exposed to superheated steam at 171 °C or 200 °C, the irradiation with gamma rays conducted prior to the steam exposure can mitigate the hydrolysis induced by the steam. Although the soft epoxy resin shows drastic changes in various properties, its properties after the aging approach or exceed the corresponding ones of the non-degraded ordinary hard epoxy resin. Therefore, it seems that using soft epoxy resin according to its purposes would not be a problem.

Актуализация национальной нормативной базы в области обеспечения пожарной безопасности электропроводок

In Russia every year, according to the statistics, the most fire hazardous types of electrical installations are electrical wiring, from which 65 % of fires occurred in 2019, associated with all the types of electrical installations. Considering the urgency of the problem, the Federal Research Budgetary Institution of the All-Russian Order of the Badge of Honor, the Research Institute of Fire Defense pays constant attention to increasing the level of fire prevention studies. One of the most important tasks in the institute activities in this Проблемы, суждения 35Безопасность Труда в Промышленности • Occupational Safety in Industry • № 11'2020 • www.safety.ru field is the development, updating, modification and harmonization of the national normative base regulating fire safety requirements and methods for assessing the fire safety of electrical installations, and, above all, of course, electrical wiring. The fundamental regulatory documents are the Technical Regulations TR EEU 043/2017 and the Federal Law of 22. 07. 2008 № 123-FZ «Technical regulations on fire safety requirements», in the development of the electrical section of which the authors of the article took an active part. Particular attention here deserves Clause 2 of Article 82, which regulates the requirements for fire resistance (operability) of cable lines and electrical wiring systems for fire protection of the objects under fire conditions, and Сlause 8 of the same article, which imposes the requirements that were awaited for a long time by all the branches of industry, agriculture, housing construction and, first of all, of course, power engineers and employees of the fire service: «Cables laid openly must be flame retardant». The requirement applies to all the objects, regardless of their functional fire hazard. Over the past three years, the Institute carried out a large scientific research and rule-making work on the revision, development and substantiation of the proposed solutions for new editions of the interstate standards for various types of electrical wiring using: molded electrical wiring products, cables of increased fire resistance under fire conditions, fire retardant cable coatings and cable penetrations. In theoretical terms, the interest is in the proposed by the authors a calculation method for assessment of electrical products fire hazard, based on the stochasticity of emergency modes that cause their failure and ignition.

АНАЛІТИЧНЕ ДОСЛІДЖЕННЯ МЕТОДІВ ОЦІНЮВАННЯ ВОГНЕСТІЙКОСТІ КАБЕЛЬНИХ ПРОХОДОК

Наведено результати аналітичного дослідження методів оцінювання вогнестійкості кабельних проходок, застосовних для їхньої європейської класифікації. Показано, що європейський підхід до оцінювання вогнестійкості кабельних проходок має особливість по відношенню до національних підходів, яка полягає в застосуванні двох методів, один з яких призначений для випробування кабельних проходок на вогнестійкість і визначення сфери прямого застосування результатів цього випробування і наведений в EN 1366-3, інший метод, наданий в EN 15882-3, – для визначення сфери розширеного застосування результатів цього випробування. Наведено особливості вищевказаних європейських методів та процедур оцінювання вогнестійкості кабельних проходок, застосовних для європейської класифікації, у порівнянні з методами і процедурами, які надано в національних стандартах, для подальшого встановлення їхньої придатності до використання на національному рівні.

ДОСЛІДЖЕННЯ ВОГНЕСТІЙКОСТІ КАБЕЛЬНИХ ПРОХОДОК ІЗ ЗАСТОСУВАННЯМ РЕАКТИВНОГО ВОГНЕЗАХИСНОГО МАТЕРІАЛУ «ЕНДОТЕРМ ХТ-150»

Наведено результати дослідження вогнестійкості кабельних проходок, у конструкції яких застосовано реактивний вогнезахисний матеріал «Ендотерм ХТ-150». Використано методику дослідження, яка ґрунтується на положеннях ДСТУ Б В.1.1-8, ДСТУ-Н Б EN 1991-1-2, ДСТУ-Н Б EN 1992-1-2. Сутність цієї методики полягає у тому, що зразки кабельних проходок встановлюють у вертикальну опорну конструкцію печі й піддають вогневому впливу. За отриманими експериментальними даними оцінюють цілісність і теплоізолювальну здатність кабельних проходок. За результатами дослідження визначено характеристики вогнестійкості кабельних проходок, у конструкції яких застосовано реактивний вогнезахисний матеріал «Ендотерм ХТ-150». Встановлено, що конструктивні параметри цих кабельних проходок суттєво впливають на їхню вогнестійкість. Так, кабельні проходки, в яких кабелі прокладено у сталевих коробах з вогнезахисним покриттям реактивним матеріалом, відповідають класу вогнестійкості EI 150. Кабельна проходка, в якій кабелі з вогнезахисним покриттям реактивним матеріалом безпосередньо проходять через огороджувальну конструкцію, відповідає класу вогнестійкості EI 90. Визначено напрям подальших досліджень, які орієнтовані на виявлення впливу параметрів сталевого кабельного короба, огороджувальної конструкції, вогнезахисного облицювання із застосуванням реактивного вогнезахисного матеріалу і марок кабелів на вогнестійкість кабельних проходок.

Влияние конструкции кабельных проходок на их пожарную опасность при эксплуатации

Влияние конструкции кабельных проходок на их пожарную опасность при эксплуатации

Radiation Oncology-External-Beam Radiation Therapy.

The application of structural shielding design techniques and goals as outlined in the National Council on Radiation Protection and Measurements Report 151, Structural Shielding Design and Evaluation for Megavoltage X- and Gamma-Ray Radiotherapy Facilities (2005), continues to be the basis for treatment vault design in 2018 with some updated information. Treatment techniques have changed significantly with the dominant usage of intensity-modulated radiation therapy techniques today based on concurrent imaging. Some of the developments in linear accelerator technology over the past 15 y include flattening filter-free modes, which enable higher instantaneous dose rates; three-dimensional conformal radiation therapy resulting in potentially higher workloads since healthy tissue is spared; improved intensity-modulated radiation therapy treatment delivery systems with lower monitor units per centigray delivered than traditional step and shoot intensity-modulated radiation therapy; stereotactic body radiation therapy with higher treatment fractions and increased workloads; and increased use of stereotactic radiosurgery with conventional linear accelerators as well as robotic arm-mounted linear accelerators with higher treatment fractions. These new treatment units also incorporate multiple-energy x-ray beams (2 to 5 MV typical), which require a significant change in the specification of a workload to be used in each vault. As the equipment in radiation oncology departments has evolved to state-of-the-art modalities, the requirements for adequate radiation shielding for these modalities has become more rigorous. Architectural designs no longer depend on standard maze design rectangular rooms. Innovative layouts and utilization of multiple layers of shielding materials allow much greater flexibility in room designs. Maze-less rooms with direct-shielded doors are part of these challenging designs and are very common today. Use of multiple-density concrete blocks allows quicker construction of vaults and requires less space for the equivalent shielding provided. Combinations of high-density or normal-density concrete, steel, and lead are used in designs to make optimum use of available space and cost. Additional shielding needed at the edges of these single- or bi-parting sliding doors as well as baffle designs for heating, ventilation, and air conditioning systems and communication cable penetrations require detailed calculations. Examples of these designs will be given in this presentation. Consideration of the radiation levels around the planned vault must also include adjacent multistory buildings.

IFMIF test cell design: Current status and key components

The IFMIF (International Fusion Material Irradiation Facility) test cell design has been further developed and optimized based on the existing modular test cell concept. Key features of the current test cell include actively cooled surrounding shielding walls with coverage of internal surfaces with stainless steel liner, independent two layer top shielding plugs for protecting the access cell from neutron and gamma radiation from the test cell, optimized piping and cabling plugs for accommodating pipe and cable penetrations and for minimizing neutron streaming, rearranged lithium quench tank to outside of the test cell, etc. According to preliminary neutronic calculation results, limited access to the quench tank area for maintenance after beam shut-off can be expected with the current arrangement. Maintenance of the lithium inlet and outlet pipes as well as the two beam ducts are also possible by introducing removable shielding plugs which can be removed and replaced in case of failure.

Risk-based coating maintenance: an integrated program

The integration of a cost-effective coating management plan into an asset integrity system is essential in ensuring asset longevity. The success of any corrosion management program relies on condition monitoring and quality auditing. Monitoring activities also contribute to maintenance plan feedback ensuring continuous improvement in corrosion management activities. It is recognised that there are many ways to organise and operate successful corrosion management programs, each of which is asset specific and depends on factors such as: Design. Stage in the life cycle. Process conditions. Operational history. AGR defines corrosion management as: “…the part of the overall management system that is concerned with the development, implementation, review and maintenance of the corrosion policy.” AGR corrosion management programs use a combination of risk-based Inspection technologies and traditional restorative maintenance activities. SOLVTM, a unique product from AGR Field Operations, is used for the management of fabric maintenance (surface coatings, insulation, passive fire protection, pipe and cable penetrations).Long-term plans: 5-year plans or longer based on client requirements. Prioritising areas and recommended maintenance intervals. Cost estimates and scope of work. Estimated condition development. Application: Treatment of component surfaces (coatings). Passive fire protection. Quality control. The benefits of the SOLVTM concept can be summarised as: Information regarding condition of maintenance objects. Preparation of fixed price maintenance plan and workpacks. Condition control through survey and audit. Cost control via quantified scope. Maintenance budget inputs for 5-year plan. Documented cost savings of 20–50 % have been realised where SOLVTM has been introduced and been used for long-term corrosion management.