Firefighting in case of Li-Ion battery fire in underground conditions: literature study
Author: Tero Välisalo
Download the report: VTT-R-00066-19_Public.pdf
The goal of this literature study is to clarify according to the available literature how the firefighters should operate in case a Li-Ion battery-powered work machine catches fire in underground conditions, e.g. in a mine. Another goal is to find ideas and topics for further research to promote fire safety of battery-powered work machines.
Battery powered electrical drives are nowadays been designed also for underground mining applications. Lithium-ion based rechargeable batteries are common also in heavy work machine applications. They are relatively safe, as there is no lithium metal present in the battery structure. However, Li-ion batteries can reach a self-heating stage that can lead to thermal runaway. All needed components of fire are present in the li-ion cell: fuel, heat and oxygen.
Lithium-ion battery fire suppression is generally recommended to be accomplished mainly with lots of pure water or water-based extinguishing foam. In underground solutions, it is not an ideal option to allow the battery pack burn to self-extinguishment because of the rock integrity decreases due to heat and because of the loss of production as the underground operations should be stopped in the case of battery fire. There were no indications in any emergency guides or research papers that there might be danger of electrical shock for the firefighters while the battery pack is extinguished with water.
To ease the work of the first responders, machine type specific instructions should be prepared. The conventional personal protective equipment used by rescue personnel in ICE car fires should be effective enough also in the case of EV battery fire, although the subject should be studied more further.
Risk assessment of machinery system with respect to safety and cyber-security
Authors: Timo Malm, Toni Ahonen & Tero Välisalo
Download the report: Safety_and_security_assessmentReportSgn19.3.2018 (002).pdf
This report is related to the concern that a cyber-security risk could cause a safety risk and furthermore an accident. There is already a tradition for how to treat safety risks related to automated machinery, but cyber-security is quite new aspect. A cyber-security issue can cause malfunction of a safety function or inherently safe design can be somehow bypassed. When looking the risks in details, it can be seen that the cyber-security/safety risk of automation is usually related to the safety integrity, availability or response time of the safety-related control system. Furthermore, the cyber-security issue is usually related to software and human access to the system.
The risk assessment processes for safety and cyber-security have similar phases, but the point of view is different. The cause of an incident is from the safety point of view usually failure, misuse or disturbance of a system whereas from the cyber-security point of view an incident may originate from a threat and vulnerability and in most cases human is causing it. We conclude that it would be difficult to benefit from a complete integration of safety and cyber-security risk assessment processes into a single analysis, because there would be so many aspects to consider and only few mutual effects. lt is recommended that the risks assessments are compiled separately, however, any identified safety-critical cyber-security issues should be added to the safety risk assessment process and associated risk treatment be validated according to safety process. The conclusion related to functional safety and cybersecurity can be mutual.