(36a) Reliability in MASS ALERT System for DAM Emergencies: Case Study of Vale S/a

Vale, the largest mining company in Brazil and one of the largest mining companies in the world, in its iron ore operations, has 75 dams considered to have High Potential Damage in case of a failure in stability controls that lead to the rupture of the containment structure of mining tailings. This classification follows the criteria of the sector's regulatory agency in Brazil and determines that, for this class, a mass alert system is necessary for the resident population and workers immediately downstream of the dam within a region established by legislation considering the simulated flood patch.

For Vale, the mass alert system for dam emergencies is part of a mitigating control within a business risk analysis considering the hypothetical dam failure as an Unwanted Material Event. To achieve this, as a critical control, it requires adequate reliability to guarantee the functionality of the control. Therefore, both the probability of failure on demand, spurious failure and asset availability are important elements for this objective, as well as the emergency response plan and the evacuation simulation of flood areas, which make up a risk management system that require continuous verification and continuous improvement.

Vale currently has 383 sirens and is expected to reach 518 sirens. The system consists of amplifiers, a digital sound system and a long-range telecommunications network for activating and monitoring assets. There are also Automatic Activation technological systems to reduce emergency response time by activating the sirens according to emergency protocol. The objective of this article is to present safety mesh concepts applied to these systems, the good practices applied from this study and the lessons learned from dam emergency management arising from the rupture of the Brumadinho dam in 2019.