Page 26 - PR 2014 2016 03 Applications of Ionizing Radiations

68 Application of Ionizing Radiations | Progress Report

Preservation of cultural heritage
objects and archived materials

Use of gamma radiation for recovery of papers infected
with fungi: case study about São Luiz do Paraitinga

Figure 41. The flooded city and wet documents.

The objective of this study is determining the optimal con-
ditions for the use of gamma radiation to recover paper doc- Three stages of this work
uments that constitute cultural heritage affected by flood have been conducted:
in the city of São Luiz do Paraitinga in Brazil in 2010. The
importance of this study comes from the unique opportunity 1. Identification of the
to perform destructive tests to documents partially destroyed genera of the fungi present
or biologically contaminated until recovered from the flooded in the selected samples to
city archives. Hundreds of blank pages from seven different establish the appropriated
books were provided by the Public Archive of the State of São radiation dose based on the
Paulo for this research. Most of these books were logbooks genus most radioresistant
or other type of registry notebooks containing blank pages.
Prior to being sent to the researchers, these books were stored 2. Comparison of the
in plastic bags for three months after being recovered from mechanical properties of
the flood, without any proper measure to prevent the devel- non-irradiated paper with
opment of microorganisms from the contaminated moist. irradiated, aged and re-
irradiated paper, including
tensile elongation and zero-
span tensile strength, and

3. Verification of the
occurrence of color variation
in mud spots and purple
and black fungi when
subjected to different doses
of gamma radiation.
Figure 42. Papers infected with fungi and culture of fungi in the laboratory for identi-
fication.

Instituto de Pesquisas Energéticas e Nucleares