In this paper the problem of volatile organic compounds control in the Gran Sasso nuclear physics underground experimental laboratory, Italy, is addressed. In particular the design and risk assessment of a carbon adsorption unit with stream recirculation for the removal of pseudocumene vapors in a nitrogen stream are discussed after a complete process characterization. The plant represents an unconventional installation in terms of required operational flexibility, materials compatibility, and safety level. The adopted technical solutions are described and the results of a Hazard Operability analysis are presented in order to identify design modifications which may contribute to further increasing system safety. (C) 2004 American Institute of Chemical Engineers.