Enrichment of nitric oxide (NO) with oxygen and nitrogen isotopes takes place in low temperature rectification plants (columns), in the condenser of which liquid nitrogen is used as a cooling agent. Nitric oxide, enriched with O‑18 (98 at. %), O‑17 (90 at. %) and N‑15 (99 at.%) are produced in different enrichment plants.

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Method of nitric oxide low temperature rectification is used for the production of nitrogen and oxygen isotopes. Isotope separation process proceeds in the complex of plants, which forms a 5-stage cascade consisting from low temperature rectification columns of different dimensions. 

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The Complex of isotope production plants composes production sites, as follows:

· Nitric oxide production site.  The target of the nitric oxide production site is to provide low temperature rectification separation plants of the Complex with initial raw material, nitric monoxide (NO).

· Nitrogen and oxygen isotopes production site. Low temperature rectification isotope separation plant is practically a high vertical pipe, enclosed in a vacuum housing. The pipe is filled with dumped packing, and evaporator and condenser are provided at the ends of the pipe to provide liquid and vapor counterflow. Liquid nitrogen is used as a cooling agent in the condenser. Process parameters in the production plants are completely controlled and maintained by the specially designed computer control system.

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The Complex of plants was designed, developed and constructed by the Company personnel and specialists. It is a unique enterprise in the world, where nitric oxide, highly enriched with three isotopes (O‑18 – 98 at. %, O‑17 – 90 at. % and N‑15 – 99 at. %) is produced simultaneously.