High Hazard Facilities Research Articles

ENSURING COTROL OF SAFE FUNCTIONING FOR FACILITIES WITH CRACKS USING ACOUSTIC EMISSION METHOD

Each type of equipment for oil and gas technologies can have cracks or crack-like defects of various origin. This fact makes us change the paradigm of the cracked structures are perceived with. It urges to develop design, design-and-experiment, and experiment methods of assessing the risks of their operation. Such an approach is increasingly relevant due to adopted regulatory documents in a number of industrially developed countries including Russia. These documents outline the standards for operation of cracked systems. Methods of linear and non-linear fracture mechanics allow to define the critical size of a crack after reaching which the crack will keep on expanding. Pig inspection allows to detect a fracture, its location and define its dimensions at the same time. However, it is dangerous to operate cracked facilities because the ambient environment may result in accumulating elastic strain energy in the membrane caused by seasonal changes. The most plausible method of relaxation is related to using cracks and crack-like defects as an energy sink through developing fractures and forming a new surface. Since there is still an apprehension that a crack of under-critical size may appear, it is suggested to fill in the detected defects with a composite material. The integrity of the materials is suggested to be controlled with acoustic emission signals. The acoustic emission method is applied to test strain-sensitive coatings that are used for high-hazard facilities when inspecting areas that are difficult to reach with visual inspections. We conducted experiments that showed that it is possible to recover the properties of cracked steel elements by using composite materials. At the same time, we researched a possibility to use acoustic emission method to control the integrity of the composite materials inside the fracture cavity. It is displayed that this method allows to conduct such an inspection and requires further studies. These studies should deal with a possibility to interpret signals related to the composite material deformation by using, for example, a cluster analysis of signals.

A method for barrier‐based incident investigation

Incident investigation is a formal requirement for high hazard facilities with the aim to learn from each incident and to prevent future recurrences. There are many published investigation methods, with most driving to the management system root cause and some applying newer barrier‐based methods. However, these methods either do not link tightly to the facility risk assessment or are very difficult to apply, and lessons from incidents that might reveal weaknesses, especially relating to major accidents, can be missed. This article describes a novel method for incident investigation (Barrier‐based Systematic Cause Analysis Technique) that combines the ideas of barrier‐based risk assessment with a well‐established systems‐based root cause analysis method (Systematic Cause Analysis Technique). The method described is efficient and can be applied by properly trained supervisors, and this potentially allows every incident or near‐miss event to be assessed in a consistent risk‐based format. The method clearly establishes links back to the facility risk assessment and thus identifies risk pathways that are potentially too optimistic (i.e., the risk is higher than predicted), and this can be due to initial optimism or degradation of safety barriers (human or hardware). © 2015 American Institute of Chemical Engineers Process Saf Prog 34: 328–334, 2015

Prioritization methodology for the decommissioning of nuclear facilities: a study case on the Iraq former nuclear complex

There are a number of sites in Iraq which have been used for nuclear activities and which contain potentially significant amounts of radioactive waste. The principal nuclear site being Al-Tuwaitha. Many of these sites suffered substantial physical damage during the Gulf Wars and have been subjected to subsequent looting. All require decommissioning in order to ensure both radiological and non-radiological safety. However, it is not possible to undertake the decommissioning of all sites and facilities at the same time. Therefore, a prioritization methodology has been developed in order to aid the decision-making process. The methodology comprises three principal stages of assessment: i) a quantitative surrogate risk assessment ii) a range of sensitivity analyses and iii) the inclusion of qualitative modifying factors. A group of Tuwaitha facilities presented the highest risk among the evaluated ones, followed by a middle ranking grouping of Tuwaitha facilities and some other sites, and a relatively large group of lower risk facilities and sites. The initial order of priority is changed when modifying factors are taken into account. It has to be considered the Iraq's isolation from the international nuclear community over the last two decades and the lack of experienced personnel. Therefore it is appropriate to initiate decommissioning operations on selected low risk facilities at Tuwaitha in order to build capacity and prepare for work to be carried out in more complex and potentially high hazard facilities. In addition it is appropriate to initiate some prudent precautionary actions relating to some of the higher risk facilities.

Hazardous material inventory reduction at nuclear and high hazard facilities

Trap Door Site (TA-22) hosts current Los Alamos National Laboratory (LANL) operations related to detonator development. The Radioactive Liquid Waste Treatment Facility (TA-50) supports TA-55 and the rest of the Lab by processing radioactive liquid waste. Designated as a Research and Development facility, the LANL Plutonium Facility (TA-55) is capable of small lot manufacturing. These three facilities are managed by the Plutonium Science & Manufacturing Directorate (ADPSM). An assessment of these facilities “as-is” material at risk quantities has been completed. Within TA-55 and TA-50, EPIcode results presented nine worse case scenarios for hazardous materials quantities, respectively. No opportunities for long-term reduction in hazardous materials were necessary at TA-22. A chlorine generator that is acceptable for use at TA-55 would eliminate the classification levels and protective action distances for chlorine. Purchasing potassium hydroxide and sodium hydroxide in containers that weigh 40 pounds or less at TA-55 and hydrochloric acid in 5 gallon containers or less at TA-50 would eliminate classification levels and protective action distances for these chemicals, as well. Pursuing these opportunities will result in a significant reduction of hazardous material containers; from 9 containers to 2. Sodium hydroxide inventory at TA-50 and nitric acid inventory at TA-55 cannot be reduced based on mission-essential needs, i.e., without increasing the overall risk to each facility. In the following report, a Hazardous Material Inventory Reduction approach for ADPSM facilities is outlined, recommendations for future opportunities to reduce chemicals are presented and hazardous material inventories that cannot be reduced based on mission-essential need discussed. Initiatives of this type contribute to ADPSM scientific and technological excellence by increasing operational safety.