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Strategies to Mitigate Ammonia Release on the International Space StationInternational Space Station (ISS) is crucial to its continuous operation. Off-nominal situations can arise from virtually any aspect of ISS operations. One situation of particular concern is the inadvertent release of a chemical into the ISS atmosphere. In sufficient quantities, a chemical release can render the ISS uninhabitable regardless of the chemical s toxicity as a result of its effect on the hardware used to maintain the environment. This is certainly true with system chemicals which are integral components to the function and purpose of the system. Safeguards, such as design for minimum risk, multiple containment, hazard assessments, rigorous safety reviews, and others, are in place to minimize the probability of a chemical release to the ISS environment thereby allowing the benefits of system chemicals to outweigh the risks associated with them. The thermal control system is an example of such a system. Heat generated within the ISS is transferred from the internal thermal control system (ITCS) to the external thermal control system (ETCS) via two, single-barrier interface heat exchangers (IFHX). The ITCS and ETCS are closed-loop systems which utilize water and anhydrous ammonia, respectively, as heat-transfer fluids. There is approximately 1200 lbs. (208 gallons) of anhydrous ammonia in the ETCS circulating through the two heat exchangers, transferring heat from the ITCS water lines. At the amounts present in the ETCS, anhydrous ammonia is one system chemical that can easily overwhelm the station atmosphere scrubbing capabilities and render the ISS uninhabitable in the event of a catastrophic rupture. Although safeguards have certainly minimized the risk of an ammonia release into the Station atmosphere, credible release scenarios and controls to manage these scenarios are examined.
Document ID
20070018136
Acquisition Source
Johnson Space Center
Document Type
Conference Paper
Authors
Macatangay, Ariel V.
(Wyle Labs., Inc. United States)
Prokhorov, Kimberlee S.
(NASA Johnson Space Center Houston, TX, United States)
Sweterlitsch, Jeffrey J.
(NASA Johnson Space Center Houston, TX, United States)
Date Acquired
August 23, 2013
Publication Date
January 1, 2007
Subject Category
Chemistry And Materials (General)
Report/Patent Number
07ICES-276
Meeting Information
Meeting: International Conference on Environmental Systems
Location: Chicago, IL
Country: United States
Start Date: July 9, 2007
End Date: July 12, 2007
Sponsors: Society of Automotive Engineers, Inc.
Distribution Limits
Public
Copyright
Other

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