Presence of a radioactive gas in archaeological excavations, determination and mitigation.
During recent archaeological discovery and excavation of a tunnel build approximately 2000 years ago by the Teotihuacans under the feathered serpent temple, in Mexico, abnormal radon concentrations up to 700 Bq m(-3) were measured at several excavation stages. The tunnel is at 15m below the earth surface with a vertical rectangular entrance of 4×4 m(2), a semi cylindrical shape of 3m in diameter, with a probable length of 100 m. This study supports the assumption that at the opening of the tunnel radon concentration was around 5500 Bq m(-3); however, although natural convection in the tunnel atmosphere naturally pups radon out, it build up to a maximum concentration of 2000 Bq m(-3). This paper presents the identification of the radon problem in this archaeological site, dose determination, and the mitigation actions that reduced the radon concentration down to 40 Bq m(-3) that ensure a negligible radon risk for archaeologist.
Instituto Nacional de Investigaciones Nucleares, Apartado Postal 18-1027, CP 11801 Mexico D. F., Mexico. Electronic address: miguel.balcazar@inin.gob.mx.
M
M
Balcázar
S
S
Gómez
P
P
Peña
J
J
Zavala Arredondo
J
J
Gazzola
A
A
Villamares
Archaeology; Excavations; Radon dose; Teotihuacan