Figure 1. Integration of six system elements and the three-tier steps in the data collection and risk analysis

Figure 2. Schematic layout of the APF

ABSTRACT

The Ammunition Process Facility in Singapore will be used for the inspection, testing and maintenance of tri-service ordnance systems for the Singapore Armed Forces. Due to the hazardous nature of the activities at this facility, a quantitative risk-based system safety assessment was conducted to evaluate the inherent individual and collective fatal risks to humans associated with the handling of ammunition in the facility. This paper outlines the methodology undertaken and conclusions drawn from the situational safety assessment based on location, infrastructure, ordnance, equipment, personnel and activity workflow. The findings from this quantitative risk assessment are also used to focus subsequent facility system safety efforts on achieving a comprehensive risk assessment and evaluation.

Alfred Tan
Francis Loi
Andreas Bienz

INTRODUCTION

The Ammunition Process Facility (APF) in Singapore, when completed, will be used for the maintenance and testing of tri-service ordnance of the Singapore Armed Forces (SAF). DSTA is responsible for the development and construction of the APF. In consideration of the potential operational and explosive hazards at the facility, DSTA decided to conduct a quantitative risk-based system safety assessment with technical consultancy from Swiss-based Bienz, Kummer & Partner Ltd (BK&P). For three decades, this risk-based safety concept (Swiss Department of Defence, 1991) has been adopted by the Swiss military in its handling of ammunition and explosives. The objectives of this assessment for the APF were two-fold: to validate the engineering and explosive safety designs of the facility, and to assess the quantitative risks associated with its operations.

APPROACH

The scope of this assessment addressed the six important elements of the facility (herein referred to as the system), namely the location, infrastructure, ordnance, equipment, personnel and procedures/workflow. Though distinct, these elements were interfaced and assessed concurrently by first identifying the five primary ordnance systems that would be processed at this facility, and then assessing the quantitative risks based on location-specific activities or situations. A thorough data collection was done to gather relevant information from various stakeholders, such as the designers and engineers developing the facility, as well as the military users and ordnance experts who would subsequently be operating the facility. Figure 1 shows the integration of the six system elements and the three-tier steps adopted in the assessment.

DATA COLLECTION
Location
A schematic layout of the APF is shown in Figure 2. Each of the two zones (A and B) consisted of a test cell, a control room, a preparation area, as well as other administrative and utility rooms. As the APF was sited at a disused granite quarry, the data collected for this system element can be further subdivided into three categories: (1) the physical footprint of the APF (2) the surroundings within the quarry and (3) the surroundings outside the quarry. Other than detailed locations of surrounding buildings and roads, the analysis sought the description of activities as well as the density of personnel and vehicle flow.

Infrastructure
With the same location categorisation, infrastructure information on the APF and its surrounding buildings were collected. This included their functions with regards to both work processes and protection against explosion effects, the type of building construction (e.g. reinforced concrete or steel-framed), the presence of any hazardous materials or unique building systems, such as blast doors, fire protection system and electrical equipment classification based on JSP 482 Standards1 (UK Ministry of Defence, 2004). For the APF, the 'net explosive quantity' (NEQ) for its functional areas was also recorded.

Ordnance
Five primary ordnance systems (T1-T5) with the highest NEQ were selected for the assessment. Other necessary information included the hazard classification (i.e. hazard division and compatibility group) according to the NATO Allied Ammunition Storage and Transport Publications (AASTP) Standards2 (North Atlantic Treaty Organisation, 2003), ordnance characteristics and packaging, as well as their utilisation (i.e. exposure) rates.

Equipment
This information included infrastructure-related equipment such as cranes, compressed air systems, as well as mechanical handling equipment and ordnance transport vehicles, either diesel- or battery-operated, that would be used under normal operations at the facility.

Personnel
The number and locations of personnel operating within the facility and in its surroundings are important in evaluating the hazard exposure rates and subsequently the individual and collective personnel risks. In this assessment, the quantitative fatal risks were calculated with a distinction made for "directly involved personnel" (i.e. working with or handling the ordnance inside the APF) and "indirectly involved personnel" (i.e. other military users in the vicinity). The public or third party was not considered explicitly in the exposure assessment due to the presence of a large out-of-bounds sterilisation area around the facility.

Procedures/Workflow
As explained in Figure 1, the procedures/ workflow information collected were based on the normal operational activities of the five primary ordnance systems that would be processed at the facility, and this information was further categorised by locations, where the number of personnel, and the nature and duration of activities were recorded.