# Red oil

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{{Short description|By-product substance}}
{{about|substances created as by-products in the nuclear reprocessing and ethylene industries|the reddish oil used in cooking and commonly called "red oil" in Nigeria and other countries|palm oil}}
{{See also|PUREX}}
{{inline|date=May 2024}} 
'''Red oil''' is defined as a substance of varying composition formed when an organic solution, typically [tri-n-butyl phosphate](/source/tri-n-butyl_phosphate) (TBP, an agent used for extracting heavy metals in [nuclear reprocessing](/source/nuclear_reprocessing) plants) and its [diluent](/source/diluent), comes in contact with concentrated [nitric acid](/source/nitric_acid) at a temperature above 120 °C.

Red oil is relatively stable below 130 °C, but it can [decompose](/source/chemical_decomposition) [explosively](/source/explosion) when its temperature is
raised above 130 °C. Three red oil events have occurred in the United States: at the [Hanford Site](/source/Hanford_Site) in 1953, and at the [Savannah River Site](/source/Savannah_River_Site) (SRS) in 1953 and 1975. A red oil explosion also occurred in 1993 at the Tomsk-7 site at [Seversk](/source/Seversk), Russia.

Generic types of equipment capable of producing red oil in the complex are categorized as [evaporator](/source/evaporator)s, acid concentrators, and [denitrator](/source/denitrator)s. The chemicals necessary to produce red oil are, at a minimum, TBP and nitric acid; other, contributory chemicals can include diluent ([kerosene](/source/kerosene)-like liquid used to dilute TBP) and/or aqueous phase metal [nitrates](/source/nitrates).

Controls for prevention or mitigation of a red oil explosion are generally categorized as controls
for temperature, pressure, mass, and concentration. Maintaining a temperature of less than 130 °C is
generally accepted as a means to prevent red oil explosions. Sufficient venting serves to keep pressure from destroying the process vessel, while also providing the means for [evaporative cooling](/source/evaporative_cooling) to keep red oil from reaching the [runaway temperature](/source/thermal_runaway). Mass controls utilize [decanter](/source/decanter)s or [hydrocyclone](/source/hydrocyclone)s to remove organics from feedstreams entering process equipment capable of producing red oil. Limiting the total available TBP is another mass control that mitigates the consequence of a red oil explosion by limiting its maximum available explosive energy. Finally, concentration control can be utilized to keep the nitric acid below 10 M (moles/liter). A U.S. government study concluded that none of the controls should be used alone; rather, they should be used together to provide effective defense in depth for prevention of a red oil explosion.

==Ethylene==
Within the [ethylene](/source/ethylene) industry, "Red oil" is an [organic](/source/Organic_compound) contaminant frequently encountered in [caustic tower](/source/caustic_tower)s. The "red oil" is an [organic polymer](/source/organic_polymer) that forms from the [aldol](/source/aldol) condensation of [acetaldehyde](/source/acetaldehyde) in [sodium hydroxide](/source/sodium_hydroxide) solution. Initially, the acetaldehyde forms a light floating yellow oil. Quickly this will continue to polymerize into a more familiar orangish/red color – hence the term "red oil". This red oil, particularly when aged, forms a more sticky heavy oil that is difficult to separate. This causes [fouling](/source/fouling) and plugging issues in the caustic tower and downstream [spent caustic](/source/spent_caustic) handling systems, making red oil a contaminant that is closely monitored in the industry.

== External links ==

* [http://www.dnfsb.gov/sites/default/files/Board%20Activities/Reports/Technical%20Reports/TECH-33.pdf Control of red oil explosions in defense nuclear facilities] ([PDF](/source/Portable_Document_Format), 120KB). [Defense Nuclear Facilities Safety Board](/source/Defense_Nuclear_Facilities_Safety_Board), 2003.
* Maugans, C.; Howdeshell, M.; De Haan, S.; "[https://www.researchgate.net/publication/267345836_The_Effects_of_Caustic_Tower_Operations_and_Spent_Caustic_Handling_on_the_Wet_Air_Oxidation_WAO_of_Ethylene_Spent_Caustic The Effects of Caustic Tower Operations and Spent Caustic Handling on the Wet Air Oxidation (WAO) of Ethylene Spent Caustic]", 2009 Ethylene Producers Conference, Tampa, FL. 2009.

Category:Radioactive waste

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Adapted from the Wikipedia article [Red oil](https://en.wikipedia.org/wiki/Red_oil) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Red_oil?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.