Preservation of documentary collections by gamma irradiation

The Brazilian Army is the custodian of invaluable cultural wealth managed by its Directorate of Historical and Cultural Heritage (DPHCEx) and whose objective is to provide technical and normative assistance for the preservation, conservation, and restoration of cultural heritage. Among the various material assets that make up the institution's cultural heritage, cartographic, iconographic and documentary collections that depict the history of Brazil and which are under the custody of the Historical Archive of the Army (AHEx) stand out. This article aims to propose, through a bibliographical survey, a complete procedure to restore documentary collections on paper using a safe methodology for disinfection and treatment by means of controlled exposure to gamma radiation. In this work the irradiation facility of the Chemical, Biological, Radiological and Nuclear Defense Institute (IDQBRN), located at the Army Technological Center (CTEx) was used, it consists of a 19 tons cavity cell irradiator endowed of ¹³⁷Cs sources, with 43 kCi activity, with a maximum dose rate of 1.45 kGy.h 1 in two rectangular irradiation chambers 68 cm wide, 137 cm long and 20 cm high positioned above and below the plane of the gamma source allowing the use of gamma radiation for the total elimination of fungi, insects and other microorganisms that deteriorate the objects of art. In this way, it is possible to conclude that, despite the complexity of the irradiation procedure of historical documents, which requires a detailed study to ensure its safe application, this is economically interesting when the equipment is available being environmentally safer than the use of chemical methods. (author)