Blast, assessment of risk case study

THE CHALLENGE

During the manufacture of ammunition systems, many pyrotechnic materials are often batch processed and stored together in significant quantities. Accidental ignition of these materials could expose nearby workers to potentially fatal injuries resulting from fire and blast. To mitigate this risk, it is vital to restrict access to areas where this danger is present.

Although our client had clearly identified safe and unsafe boundaries for their workers, these areas did not account for the effects of protective mounding that exists on the site. This assumption was felt to be potentially overly restricting operations on the site, but a more realistic assumption could not be justified without a more complex analysis. 

To ensure that the risks were fully understood, Frazer-Nash was commissioned to conduct a more comprehensive assessment of the effects of an accidental explosion or fire, taking into account details of the plant layout and the protective mounding.

OUR SOLUTION

We began by undertaking a comprehensive study into the development and propagation of blast pressure from a range of explosions within the manufacturing building. We developed a computer model to simulate the blast propagation, which enabled us to identify areas of peak overpressures and estimate the threat of injury to personnel.  At the same time, we also developed a CFD computer model to assess the thermal effects from an event involving a fire rather than an explosion.

We then developed these models to assess a wider variety of scenarios, including an assessment of the sensitivity of parameters including mound size, shape and location. 

The results were applied to the detailed storage area layout, providing a more in-depth analysis of the blast propagation and thermal effects on our client's actual storage area. 

Finally, we then developed these models to include different masses of explosive material, allowing the results of the assessment to be applied to different facilities, mounding positions and configurations. 

THE OUTCOMES

Our comprehensive analysis provided our client with a more realistic assessment of the actual fire and blast risks which exist on their site. The effect of the protective mounds on heat and blast propagation meant that the distances required for personnel safety were able to be reduced and justified in a revised safety case.

The results of the propagation and sensitivity studies also allowed more general conclusions to be made about the effect on areas around buildings which will inform any future safety studies our client may undertake.