Retrospective dosimetry with the MAX/EGS4 exposure model for the radiological accident in Nesvizh-Belarus

• Published in: Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment Vol. 580; no. 1; pp. 621 - 624
• Main Authors: Santos, A.M., Kramer, R., Brayner, C.A., Khoury, H.J., Vieira, J.W.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 21.09.2007
• Subjects: Human phantoms; Monte Carlo methods; Radiological accidents; Radiological accidents; Human phantoms; Monte Carlo methods; 87.53.Dq; 87.53.Bn
• ISSN: 0168-9002; 1872-9576
• DOI: 10.1016/j.nima.2007.05.024

On October 26, 1991 a fatal radiological accident occurred in a 60Co irradiation facility in the town of Nesvizh in Belarus. Following a jam in the product transport system, the operator entered the facility to clear the fault. On entering the irradiation room the operator bypassed a number of safety features, which prevented him from perceiving that the source rack was in the irradiation position. After the accident average whole body absorbed doses between 8 and 16 Gy have been determined by TLD measurements, by isodose rate distributions, by biological dosimetry and by ESR measurements of clothes and teeth. In an earlier investigation the MAX/EGS4 exposure model had been used to calculate absorbed dose distributions for the radiological accident in Yanango/Peru, which actually represented the simulation of exposure from a point source on the surface of the body. After updating the phantom as well as the Monte Carlo code, the MAX/EGS4 exposure model was used to calculate the absorbed dose distribution for the worker involved in the radiological accident in Nesvizh/Belarus. For this purpose, the arms of the MAX phantom had to be raised above the head, and a rectangular 60Co source was designed to represent the source rack used in the irradiation facility. Average organ absorbed doses, depth-absorbed doses, maximum absorbed dose and average whole body absorbed dose have been calculated and compared with the corresponding data given in the IAEA report of the accident.