Title : Freon change in ASR-8 radar < Type : Antarctic EAM NSF Org: OD / OPP Date : August 4, 1993 File : opp93113 OFFICE OF POLAR PROGRAMS ENVIRONMENT SECTION 202/357-7766 MEMORANDUM Date: August 4, 1993 From: Acting Environmental Officer Subject: Environmental Action Memorandum (Conversion of Waveguide Pressurization Agent of the AN/GPN-27 (ASR-8) From Freon- 12 To Sulfur Hexafluoride on the ASR-8 Radar) To: Director, Office Of Polar Programs Manager, Polar Operations Associate Manager,(DOD) Commander, Naval Support Force Antarctica Head, Safety, Environment and Health Implementation Team Safety and Health Officer Environmentalist, ASA This Environmental Action Memorandum describes the need for a proposed action to replace existing pressurization agent from Freon-12 to Sulfur Hexafluoride in the ASR-8 Radar. The Acting Environmental Officer posed a set of questions relating to the proposed project, and to the potentially affected environment. These questions were responded to by LCDR C. M. Rhone of the Naval Support Force, Antarctica on July 1, 1993; the questions and responses are shown below. Environmental Assessment Queries and Responses GENERAL 1. What is the specific purpose of the proposed activity? The purpose of the activity is to replace existing pressurization agent from Freon-12 to Sulfur Hexafluoride in the ASR-8 Radar.The activity will consist of removing Freon-12 bottle and regulator and installing a bottle of Sulfur Hexafluoride and a new regulator in the existing space occupied by the Freon-12 system. What alternatives to the proposed activity have the Program and the Contractor considered? None, Sulfur Hexafluoride has been tested, studied and used as a waveguide pressurization agent for many years. Have probable impacts of all alternatives been considered by the Program and the Contractor? Please explain how. (1) The impact of removing the Freon-12 system, a known ozone depleting material, with Sulfur Hexafluoride can only be beneficial to the environment. (2) Attached is information taken from a study by Naval Electronic Systems Engineering Center, Charleston, on properties of Sulfur Hexafluoride. Should the chosen alternative involve potential impacts, how would these impacts be mitigated by the Program or the Contractor? Not applicable, as per Naval Electronic Systems Engineering Center. Have measures to assess the indirect costs of the proposed activity been identified or considered by the Program or the Contractor? Please explain how. The modification is designed to mitigate impacts. No indirect costs have been identified. LAND USE AND PLANNING 2. Where would the proposed activity be located, specifically? The modification will take the place of the already existing Freon-12system at the McMurdo ASR-8 radar site. Have alternative locations been considered by the Program or the Contractor? If yes, which are they; if no, explain why. Pressurization system must be installed in the vicinity of the waveguide to be pressurized. (3) How would any aesthetic impacts to the area from the proposed activity be handled by the Program or the Contractor? There are no aesthetic impacts. The system components will be installed in existing facilities. 4. Would the proposed activity have any other indirect impacts on the environment? If yes, what are they; if no, explain why none are expected. None, replacement for existing system. 5. Would the proposed activity change the traditional use(s) of the proposed (or chosen) site? If yes, how; if no, why. No, the system supports equipment already in place. 6 Are the physical and environmental characteristics of the neighboring environment suitable for the proposed activity? If yes, explain why; if no, explain why. Yes, it is a direct replacement for pressurization system already in place. IMPACT AND POLLUTION POTENTIAL AND ENVIRONMENTAL MANAGEMENT: 7. How has protection of the environment and human health from unnecessary pollution or impact been considered for the proposed activity (includes such considerations as pollution abatement or mitigation, and waste management [e.g., of noise, dust, fuel loss, disposition of one-time-use materials, construction wastes])? The pressurization system is a sealed designed with a system purge, as part of maintenance occurring about two times a year. System uses a rechargeable gas bottle, creates no waste, and requires no construction materials, and has no one-time- use materials. 8. Would the proposed activity change ambient air quality at the proposed (or chosen) site? If yes, how; if no, why. See enclosure (1). 9. Would the proposed activity change water quality or flow (drainage), at the proposed (or chosen) site? If yes, how; if no, why. No. The system will support activity that is already occurring and will not alter any drainage at the site. 10. Would the proposed activity change waste generation or management at the proposed (or chosen) site? If yes, how; if no, why. Possible, as for transfer of empty bottles to be refilled and brought back. 11. Would the proposed activity change energy production or demand, personnel and life support, or transportation requirements at the site? If yes, how; if no, why. None. 12. Is the proposed activity expected to adversely affect scientific studies or locations of research interest (near and distant, in the short-term)? If yes, how; if no, why. No. The system is located within existing structures and should not disturb any scientifically important area. 13. Would the proposed activity generate pollutants that might affect terrestrial, marine or freshwater ecosystems within the environs of the station or inland camp? If yes, how; if no, why. See enclosure (1). 14. Does the site of the proposed activity serve as habitat for any significant assemblage of Antarctic wild life (for example, mosses or lichens, or Antarctic birds or marine mammals)? No. The system will be installed within an existing structure. HUMAN VALUES: 15. Would the proposed activity encroach upon any historical property of the site? If yes, how; if no, why. No. The system will be installed within an existing structure. OTHER CONSIDERATIONS 16. What other environmental considerations may be potentially affected by the proposed activity at the proposed (or chosen) site? for example, have impacts associated with decommissioning of the activity been considered (and how). None. REPLACEMENT OF FREON-12 WITH SULFUR HEXAFLUORIDE Environmental Concerns In the process of selection of a waveguide pressurization agent, it was determined [1] that the presence of chlorine in FREON-12 resulted in free chlorine ions catalyzing recombination of ozone into ordinary oxygen in the stratosphere. Therefore, a necessary condition for a candidate gas to be considered was that it could not contain chlorine. Sulfur hexafluoride does not contain chlorine. Sulfur hexafluoride does not break down in the environment. In itself, sulfur hexafluoride is extremely inert and, in low concentrations, presents no hazard. There has been some recent mention of sulfur hexafluoride as a possible future contributor to the greenhouse effect. no quantitative data is available regarding the quantities of sulfur hexafluoride which would be needed, or whether the physics of a scenario of sulfur hexafluoride as an appreciable greenhouse effect agent is viable. No EPA regulations concerning sulfur hexafluoride are contemplated at this time. In the event that traces of sulfur hexafluoride are carried into the stratosphere and ionized, sulfur and fluorine will be released and combined in traces with other elements. Sulfur and Fluorine are common light elements which have not been identified as environmental hazards in very low concentrations. Fluorine is a component of FREON-12 and has not been identified as an environmental concern as chlorine has. Sulfur hexafluoride has been commercially available since about 1950 and no environmental hazard has ever been attached to low concentrations of this gas or traces of its breakdown products. Chemical and Toxic Properties FREON-12 is a very mild intoxicant and breathing its vapors should be avoided. Sulfur Hexafluoride is one of the most inert gases known, and experiments have been done using an atmosphere of 80% sulfur hexafluoride and 20% oxygen in a cage of mice for weeks with no noticeable effects. FREON-12 will produce minute quantities of chlorides and fluorides of the waveguide material with trace quantities of more complex chlorofluorocarbons if arcing occurs within the waveguide. In the presence of air or water vapor, phosgene gas (COCL2) is produced. Phosgene gas is extremely toxic. Traces of air and water vapor are inevitable unless the waveguide is pumped down to a vacuum. The pressure tolerances of the AN/GPN-27 diplexer windows will not allow pumping down to a vacuum. Therefore, when waveguide arcing is observed, the system should be purged. Sulfur hexafluoride will produce minute quantities of fluorides of the waveguide material and SF4 if arcing occurs within the waveguide. Other chemical products are not observed because the SF6 simply reforms after the arc stops. This property is used to advantage in some newer high-power circuit breakers, which use sulfur hexafluoride jets to quench arcs resulting when the breaker opens. The resulting gas mixture, with traces of SF4, will not have an increased susceptibility to arcing and its toxic properties will be very low. However, in the presence of air or water vapor, small quantities of SOF2 will be formed. This gas is toxic, but not as toxic as phosgene gas. SOF2 has a very strong "rotten egg" odor, so to extensive arcing. In the event that this occurs, the system should be purged using the same procedures as recommended for purging the FREON-12. In the event of a fire, a full bottle of FREON-12 could exceed the critical point and boil to a gas, which would then exceed the pressure ratings of the bottle, flexible hose, pressure switch, and regulator used with FREON-12 on the AN/GPN-27. The result could be the release of FREON-12 into the flames, generating large quantities of phosgene gas and other toxic products. In the event of a similar fire where sulfur hexafluoride is used, the pressure ratings would not be exceeded, and if the gas were released, it would serve to extinguish the flames. Finding The Acting Environmental Officer, after reviewing the information presented above, believes that the proposed activity poses neither potentially minor nor transitory/no significant impacts to the antarctic environment. In fact, there are recognized environmental benefits that would accrue from undertaking the completion of the proposed project. The military contractor is authorized to proceed with the proposed activity. Jane Dionne Encl: Excerpt from Naval Electronic Systems Engineering Center, Charleston, conversion guide for the ASR-8.