Advanced Silicon Materials Inc. - Executive Summary |
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Facility Information Advanced Silicon Materials Inc.'s (ASiMI) Moses Lake, Washington facility is a manufacturer of silane and polycrystalline silicon for the electronics industry. ASiMI occupies an 80-acre plot, which is located 5 miles east of Moses Lake, Washington on Road "N" NE. The neighborhood is predominantly agricultural with several food processing plants, another chemical manufacturing facility, an industrial gas cylinder filling facility and a corrugated cardboard production plant in the vicinity. Process Overview The ASiMI facility in Moses Lake, WA is comprised of three different production units: 1) Silane, 2) Poly Reaction, and 3) Product Finishing. The Silane Unit, through a series of chemical reactions and separation steps, converts metallurgical silicon and hydrogen to a high purity silane gas. Intermediates produced in the process are trichlorosilane and dichlorosilane. Some of the silane is packaged in tube trailers and modules and temporarily stored prio r to sale. The Poly Reaction Unit uses the majority of the silane and converts it into hydrogen and polycrystalline silicon. The hydrogen is recycled back to the Silane Unit and the polycrystalline silicon is forwarded to the Product Finishing unit for mechanical processing and packaging. There is one covered "process" as defined by the RMP regulations at the Moses Lake facility. This process includes the Silane and Poly Reaction production areas which are interconnected, and the silane module storage area located adjacent to the Silane production area. Together these areas are identified as the Polysilicon Manufacturing process. This risk management plan uses "predictive filing" to account for variables in the total quantities of chemicals at the facility, and for planned changes to the facility. With predictive filing, the maximum quantity of chemicals that would be in the process at any one time is specified in this plan. Chemicals: Advanced Silicon has identified the foll owing chemicals and maximum on-site quantities, which trigger compliance with the Risk Management Program (RMP) standards, 40 CFR Part 68: Trichlorosilane 200,000 pounds Silane 300,000 pounds Dichlorosilane 25,000 pounds Hydrogen 9,100 pounds Hydrogen is also included in the plan, though the maximum quantity on site is less that the regulated threshold of 10,000 pounds. All RMP applicable chemicals at the source are classified as flammables. In addition to the above RMP-covered chemicals, Advanced Silicon has identified other potentially hazardous chemicals which could have either onsite or offsite impacts. Risks from both these non RMP-covered chemicals as well as the RMP-covered chemicals are minimized using similar design standards, procedures, controls, mitigation measures, and emergency response procedures. Advanced Silicon is also working with the local Department of Emergency Management and the Local Emergency Planning Committee to coordinate emergency planning and e mergency response for all potentially hazardous chemicals. Worst-Case Scenarios: Four hypothetical worst-case scenarios were identified and developed for the facility in accordance with RMP standards: The full hydrogen storage tank releases its entire contents, 8,500 pounds of hydrogen, which explodes with 10% explosion efficiency and no mitigation. The calculated distance to 1-psi overpressure is 0.23 miles. Public receptors within that radius are cultivated and uncultivated fields, and an industrial gas cylinder filling facility normally occupied by 2 persons during the day. A full high-pressure silane storage tank releases its entire contents, 20,000 pounds of silane, which explodes with 10% explosion efficiency and no mitigation. The calculated distance to 1-psi overpressure is 0.22 miles. Public receptors within that radius are cultivated and uncultivated fields, and an industrial gas cylinder filling facility normally occupied by 2 persons during the day. A full liquid s ilane storage tank releases its entire contents, 22,000 pounds of silane, which explodes with 10% explosion efficiency and no mitigation. The calculated distance to 1-psi overpressure is 0.22 miles. Public receptors within that radius are cultivated and uncultivated fields with no population. A polycrystalline silicon furnace releases its entire contents of hydrogen and silane, totaling 38 pounds, which explodes with 10% explosion efficiency and no mitigation. The calculated distance to 1-psi overpressure is 0.04 miles. Public receptors within that radius are an employee picnic area with approximately 6 persons in the area for 1 hour per day. Alternative Scenarios Two hypothetical alternative scenarios were identified and developed for the facility in accordance with RMP standards: A silane tube trailer safety device fails and releases the entire tube contents, 1700 pounds of silane, the contents of the gas jet (73 pounds) explodes with 100% efficiency and no mitigation. The c alculated distance to 1-psi overpressure is 0.07 miles. Public receptors within that radius are cultivated and uncultivated fields with no population. This scenario was selected as it was the only alternative scenario with off-site impact. A hose transferring trichlorosilane from a process vessel fails and releases the entire vessel contents of 230 pounds of trichlorosilane, which explodes with 3% explosion efficiency and no mitigation. The calculated distance to 1-psi overpressure is 0.02 miles. There are no public receptors, only on-site impact. The conservative efficiency selection of 3% was based on published literature indicating an efficiency of 2% is typical for vapor cloud explosions. Accident History In the past five years Advanced Silicon has experienced 5 accidental releases as defined by the RMP standards. The largest was a release of 80 pounds hydrogen and 6200 pounds trichlorosilane on 10/8/98, which caused significant on-site impacts. Off-site, this resulted in property and crop damage, and several residents were advised to shelter in place. The other 4 accidental releases only caused on-site impacts, but local industries were advised to shelter employees in place as a precaution during the 8/31/94 release. Accidental Release Prevention Program Advanced Silicon's accidental release prevention program is based on the following essential elements: hazard reviews of equipment and processes, preventative and predictive maintenance programs, a management of change program, operator job certification and performance testing, accurate operating procedures, internal and external auditing and inspection programs, accident and near-miss investigations, etc. Advanced process monitoring and control systems are in use at the facility, and critical parameters are monitored with duplicate instrumentation. Loss of utilities is protected against through the use of installed and routinely tested back-up systems. Engineering and design standards ensu re materials and equipment meet industry specifications. Advanced Silicon is known as an industry leader in silane handling safety. Emergency Response Program Advanced Silicon's emergency response program has been coordinated with the local Department of Emergency Management and LEPC. The program includes information on locations, quantities, and associated hazards of materials at the facility, as well as fixed and portable methods for containment and/or suppression of spills and releases, internal and external notification and communications procedures, alarm systems and evacuation plans. The facility itself is designed with numerous mitigating features, including containment and diking, deluge systems for fire and vapor suppression, strategically-placed fire hydrants and fire monitors, and emergency scrubber systems. Automatic and manual shutdown systems as well as automatic isolation valves are in place. Back-up fire water supplies and firewater pumps are installed. Emergenc y equipment is routinely maintained and tested. In addition, Advanced Silicon maintains a highly skilled emergency response team on-site 24-hours a day. The team performs realistic monthly drills and exercises, covering a variety of response scenarios such as spill containment and cleanup, vapor suppression, fire fighting, and response to injuries. Planned Changes to Improve Safety Advanced Silicon continues to seek and identify opportunities to improve safety through process hazard analyses, safety reviews and inspections, internal and external audits, incident and near-miss investigations, employee and safety committee suggestions, etc. For example, a number of recommended actions to improve safety were identified in the latest external audit. These recommendations are currently being reviewed and implemented as required. |