Jennie-O Melrose - Executive Summary
1.0 SOURCE AND PROCESS DESCRIPTION |
The Jennie-O Foods, Inc. Melrose facility is a 118,992 ft2 processing facility consisting of the slaughter, deboning, packaging and shipping of turkey. The Melrose facility is subject to the USEPA's Risk Management Program (RMP) for Accidental Chemical Release regulation (40 CFR 68) because it has a refrigeration system that contains more than the threshold quantity (10,000 pounds) of anhydrous ammonia (CAS Number 7664-41-7). The anhydrous ammonia (ammonia) refrigeration system is used to control the temperature for turkey processing and packaging. The entire system contains approximately 45,000 pounds of ammonia in various physical states (gas, liquid, and saturated vapor). The largest vessel is the high pressure receiver that operates between 140 and 195 psig and can contain as much as 20,800 pounds of liquid ammonia, assuming a 90 percent fill volume. However, during typical operation, the vessel holds only 8,300 pounds. Most of th
e ammonia equipment is located indoors. The condensing towers and some piping are located outdoors.
1.2 Process Description
The ammonia refrigeration system at the Melrose facility is a two-stage system consisting of a high pressure side and a low pressure side. The low side (i.e., low pressure) is intended to quickly freeze product, while the high side (i.e., high pressure) is intended to refrigerate the product. Equipment and piping carry the necessary gas, liquid, and saturated vapor throughout the system.
The ammonia refrigeration system is protected by the existence of specific safety systems/hardware, including safety relief valves (SRVs), engine room ventilation, and system safety interlocks. SRVs protect the compressor discharge, condensers, pumper drums, accumulators, and pump-out system from the hazards associated with over-pressure. Safety interlocks include high pressure and high temperature alarms and cutouts for the compressors, as well as high level floats and s
ensors for the vessels.
2.0 POTENTIAL RELEASE SCENARIOS
As required by the RMP rule requirements, two specifically defined release scenarios (a worst-case release and an alternative release) were analyzed to determine the maximum distance to an endpoint where the ammonia concentration is 200 parts per million in air, or 0.02 percent.
The release scenarios analyzed are based upon the guidance contained in the USEPA's Model Risk Management Program and Plan for Ammonia Refrigeration (the "Model Plan"), dated May 1996. This guidance document used the SACRUNCH atmospheric dispersion model to construct "lookup" tables that relate the quantity and rate of ammonia released to the endpoint distance.
2.1 Worst-case Release
The worst-case release is defined by the catastrophic rupture and complete loss of the contents of the largest vessel and associated piping (approximately 20,800 pounds of ammonia) over a 10-minute period. Using the specified worst-case meteorology contained in the "Model P
lan" and assuming the facility is located in a rural area, the distance to the endpoint for a worst-case release was estimated to be 14,250 feet or 2.7 miles. The total residential population within the worst-case release is 2654. Public receptors include schools, hospitals, and recreational areas. Lastly, there is one sensitive environmental receptor within the boundaries of the worst-case impact area, a National Waterfowl Production Area.
Although the worst-case consequence analysis is required by the RMP, it should be considered a highly unlikely event. Design, construction, and operation of the high pressure receiver is such that catastrophic failure is extremely remote. The receiver was designed and constructed in strict accordance with the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (Section VIII), and was certified and stamped by the National Board of Pressure Vessel Inspectors (National Board). Third party and state mandated inspection
s of the vessel's condition occurs every three years by a Hartford Steam Boiler and Insurance Company's inspector who has been certified by the National Board.
The vessel is operated well below the design pressure (i.e., maximum allowable working pressure) and because of the safety factors built into the ASME Code, a fourfold pressure excursion would have to occur before catastrophic vessel failure. If this were to occur, the vessel is equipped with dual safety relief valves (SRVs) set to relieve internal pressure at 250 psig. A high pressure excursion would not occur as long as the SRVs continued to function. Actuation of the SRVs would result in an ammonia release similar to that described in Section 2.2 for the alternative release scenario. The SRVs are replaced every five years, in accordance with the International Institute of Ammonia Refrigeration (IIAR) guidance contained in IIAR Bulletin Number 109, Minimum Safety Criteria for a Safety Ammonia Refrigeration System, to ensu
re that they will function properly when required.
The worst-case release scenario is unlikely for the following additional reasons:
7 The facility is protected by a sprinkler system;
7 An ammonia detector exists in the engine room;
7 The facility has a preventive maintenance program in place to maintain the ongoing integrity of the vessels;
7 The facility has a training program designed to ensure that the system is operated by qualified personnel;
7 The facility has emergency response procedures which enable trained personnel to respond quickly to isolate any potential releases;
7 Vehicular traffic in the area of the high pressure receiver is limited to only a few times a year.
2.2 Alternative-case Release
The alternative scenario is defined by a release of ammonia that is more likely to occur than the worst-case scenario, and reaches an endpoint offsite.
The "Model Plan" scenario was used for this analysis, which assumes a release of ammonia through a <-inch effective diameter h
ole in a high side (i.e., 150 psig) pipe or vessel, releasing 91.5 pounds of ammonia per minute. Because the building can serve as a passive mitigator to this release, passive mitigation was used to reduce the release rate and the distance to the endpoint.
Using the specified meteorology contained in the "Model Plan", the distance to the endpoint for the "more likely" release scenario was estimated to be 720 feet or 0.14 miles. The total residential population within the alternative-case release impact area is 33. Public receptors include a school and a recreation area.
The alternative release scenario is unlikely for the following reasons:
7 Industrial standards were followed for the manufacture and quality control of these lines;
7 The facility has a preventive maintenance program in place to maintain the ongoing integrity of the system;
7 The facility has a training program designed to ensure that the system is operated by qualified personnel; and
7 The facility has emergency
response procedures which enable trained personnel to respond quickly to isolate any potential releases by closing isolation valves in the liquid lines.
3.0 PREVENTION PROGRAM
The Melrose facility has carefully considered the potential for accidental releases of ammonia, such as the occurrence of the worst-case and alternative-release scenarios described in Section 2.0. To help minimize the probability and severity of an ammonia release, a prevention program that satisfies the Occupational Safety and Health Administration (OSHA), Process Safety Management (PSM) of Highly Hazardous Chemicals (29 CFR 1910.119) has been implemented. The key components of the prevention program are summarized below:
7 The development of an employee participation program, which includes Melrose facility employees from all areas within the plant (i.e., production and maintenance).
7 The development, documentation, and operator availability of critical process safety information regarding the hazards of a
mmonia, the design basis of the system, and the equipment. This information is used to fully understand and safely operate the ammonia refrigeration system.
7 The performance of a formal process hazard analysis (PHA) on the ammonia refrigeration system using a Hazard and Operability (HAZOP) Study, coupled with a specialized "What-If" Protection Analysis. A team with expertise in engineering, operations, maintenance, and safety evaluated the existing refrigeration system in depth and developed recommendations to improve the safety and operability of the system. The PHA resulted in recommendations to improve the safety and operation of the refrigeration system. The PHA is updated and revalidated every five years.
7 Standard operating procedures (SOPs) are used to provide the basis for proper and safe operation of the ammonia refrigeration system. The SOPs include procedures for normal operations, startup, shutdown, emergency operations, and emergency shutdown. They also describe saf
e operating limits for temperature and pressure, the consequences of operating outside these safe operating limits, and a description of safety systems and how they operate.
7 Refrigeration system operators receive refresher training at least every three years. The training content is based on the process safety information and operating procedures. The training program ensures that the operators understand the nature and causes of problems arising from system operations and serves to increase awareness with respect to the hazards particular to ammonia and the refrigeration process.
7 Contractors that are hired to work on, or adjacent to, the refrigeration system are "pre-qualified" based on their knowledge of ammonia refrigeration, understanding of applicable codes and standards, and their demonstrated ability to work safely. In addition, these contractors are periodically evaluated to ensure that they continue to work safely.
7 A Jennie-O Foods, Inc. refrigeration system computer
preventative maintenance program is utilized at the Melrose facility. This includes regular inspection and calibration of liquid level sensors, temperature and pressure instruments, switches and shutdown devices that have safety implications. Also included is the regular inspection of major powered equipment, including compressors, pumps and large fans, bearings, couplings, shaft seals, mountings, etc., for vibration or incipient mechanical failure.
7 Utilization of safety systems, including pressure relief valves, monitors, and ammonia vessel level controls and safety interlocks.
7 Formal authorization systems (i.e., management of change procedure, pre-startup safety review) are in place to ensure that system changes or expansions are as safe as the original design and that an independent recheck confirms that the changes are consistent with the engineering design and in a condition to be safely operated prior to startup.
7 Events that might cause an accidental or unexpected release
of ammonia are subjected to a formal investigation. The objective of the investigation is to correct deficiencies in such a way as to prevent recurrence.
7 Prior to the performance of any hot work (i.e., spark or flame producing operations such as welding, cutting, brazing, grinding), management must approve the work by executing a written hot work authorization permit to verify that precautions to prevent fire have been implemented.
7 Planning with the local fire department to ensure a rapid response to potential incidents with the system or external events, such as floods or tornadoes.
7 Prevention program compliance audits are performed every three years to verify that the appropriate management systems are in place and are being properly implemented. Any deficiency found in an audit is corrected.
4.0 ACCIDENT HISTORY
There have been no accidental releases of ammonia at the facility in the last five years that have resulted in death, injury, or significant property damage on site
or off-site death, injury, evacuation, sheltering in place, property damage, or environmental damage.
5.0 EMERGENCY RESPONSE PROGRAM
The Melrose facility has implemented a detailed written Emergency Response Plan (ERP). The ERP is intended to address all emergencies at the facility, in addition to incidents related to a release of ammonia. The ERP includes:
7 Coordination with the local fire department and with the Local Emergency Planning Committee (LEPC);
7 Emergency escape procedures and emergency escape route assignments;
7 Procedures to be followed by employees who remain to operate critical plant operations before they evacuate;
7 Procedures to account for all employees after emergency evacuation has been completed;
7 What personal protective equipment and spill response equipment is available;
7 The preferred means of reporting fires and other emergencies;
7 Names of persons or departments who can be contacted for further information or explanation of duties under the plan;
7 Designation and training of a sufficient number of persons to assist in the safe and orderly evacuation of employees;
7 The names of personnel: (1) responsible for maintenance of equipment and systems installed to prevent or control ignition, and (2) responsible for control of fuel source hazards; and
7 Procedures for handling releases of ammonia.