Según la Resolución de Presidencia Nº 132-11-IPEN (09 de junio de 2011) el párrafo 611 de la Norma Técnica N° PR.002.2011 “Requisitos Técnicos y Administrativos para los Servicios de Dosimetría Personal de Radiación Externa” disponía:
"611. Los dosímetros con dosis mayores a 50 mSv y que pueden ser releídos, se conservarán durante un año." /1/
Mediante Resolución de Presidencia Nº 240-12-IPENse ha modificado el párrafo 611 de la Norma Técnica N° PR.002.2011, que ha quedado redactado de la manera siguiente:
“611. En caso que se presenten reportes de dosis mayores a 50 mSv, el proveedor del servicio debe otorgar las facilidades que requiera específicamente la Oficina Técnica de la Autoridad Nacional para realizar la verificación del proceso”. /2/
La referida Norma Técnica fue aprobada el año 2011 por Resolución de Presidencia Nº 132-11-IPEN/PRES y contiene los requisitos administrativos y técnicos que deben cumplir los servicios de dosimetría externa de radiaciones, con fines de autorización por parte de la Oficina Tecnica de la Autoridad Nacional, siendo de aplicación para las entidades u organizaciones que llevan o vayan a llevar a cabo servicios de dosimetría personal de radiación externa a nivel nacional.
Teniendo en cuenta que el IPEN es el promotor de las bondades de la tecnología nuclear y quien contribuye con la protección de la población de los riesgos que involucran las radiaciones ionizantes, ha tenido, desde los inicios de la actividad nuclear en el país, una especial preocupación por la salud y bienestar de quienes están ocupacionalmente expuestos a radiaciones, por tal motivo realiza diversas acciones que permitan mantener e incrementar la cultura de prevención en materia de seguridad y salud, que comprende una serie de protocolos que deben ser estrictamente cumplidos por los respectivos usuarios.
A radiographer was taking several radiographic films to pipes by the night. In order to be sure that the guide tube was correctly aligned the radiographer approached to the guide tube and collimator to fix them over the pipe. This operation was repeated by 40 times. Eventually the radiographer touched the tip of guide tube with his left hand where the source was unnoticed disengaged, at least 10 times. Also, as radiographer performed this operation two auxiliary staff approached to him carrying the films to be placed for the radiography, at least by 20 to 40 times. The radioactive source was 3199,5 GBq of 192Ir. The event was detected at the end of the job and the radiographer advised to the safety officer who jointly with other licensed operator recovered the radioactive source in a safely manner. Operator showed mild symptoms as nausea and vomiting at the end of job. The other auxiliary people showed just nausea symptoms. The symptoms finished after some hours. The finger of the operator showed blistering at the fifth day. Based in biological dosimetry the radiographer received a whole body doses of 1,86 Gy. The dose to his left hand was 35 Gy as average but the dose to the distal falange (finger) was 70 Gy, both based on electron paramagnetic resonance (EPR). The doses to assistants were 0,45 Gy and 0,75 Gy to whole body, based on biological dosimetry. The personnel were promptly admitted to the hospital for clinical analysis and medical examination. The operator was after derived to France (Percy Militar Hospital) for treatment but part of his finger was amputated. Currently he has returned to Peru and, according the medical evaluation, his health is good stable and going to recovery, but psychological treatment has been advised. The assistants are just under out-patient medical follow up. ______________________________________ A radiographer was taking several radiographic films to a pipes by the night. In order to be sure that the guide tube was correctly the radiographer went to the tube guide an collimator to fix them. This operation was made by 40 times. Eventually the radiographer touched with his left hand, at least 10 times, the tube guide where the source was unnoticed. Also, two auxiliar staff went to the radiographer position carrying the films to be checked at least by 40 and 20 times. The radioactive source was 3199,5 GBq Ir-192. The event was detected at the end of job. The radiographer adviced to radioprotection officer who jointly to other operator rescued the radiactive source in safely manner. Operator showed mild symptoms as nausea and womiting and other just nausea, but after all this symptoms are finished. The finger of operator showed a blistering at the fifth day. Based in first calculations, symptoms and dosimeter reading the operator could have received 6 - 7 Gy to whole body and > 50 Gy to finger. The other personnel could have received doses from 1 to 3 Gy. Currently the personnel is being admitted to the hospital and citogenetic dosimetry will be performed to adjust the doses.
INES Rating: 3 - Serious incident (Provisional) as per 17 January 2012
Release beyond authorized limits?
No
Overexposure of a member of the public?
No
Overexposure of a worker?
Yes
Contamination spread within the facility?
No
Damage to radiological barriers (incl. fuel damage) within the facility?
No
Degradation of Defence In-Depth
No
Person injured physically or casualty?
Yes
Is there a continuing problem?
No
Renan Ramirez Instituto Peruano de Energia Nuclear
Since Teflon is a bad conductor of heat, in many readers the thermoluminescence of a CaSO4 Teflon TLD disc is erased only partially during the first read-out; the second and even the third TL read-outs are functions of the absorbed dose. This offers a simple method of re-estimation of absorbed dose. The present study has shown that, as might be expected, the efficiency of dose re-estimation by the above method in CaSO4:Dy Teflon TLDS, is independent of the photon energy of the incident radiation in the range 30 keV - 1.25 MeV as well as of the irradiation history. Annealing at 240 oC was found to restore the original as well as the re-estimated TL sensitivity after a gamma dose of 0.12 Gy. This is unlike the case with PTTL technique in LiF. The above differences arise because in the first method, the re-estimated TL is still a characteristic of dosimetry traps whereas the PTTL is a characteristic of deep traps.
The technique of ultraviolet light bleaching for the re-estimation of the absorbed dose of radiation received by lithium fluoride thermoluminescence dosemeters has been extended to the extruded ribbon and PTFE disc form of dosemeter. The threshold of detection for the re-estimation of absorbed dose was found to be 1-1 rad for the PTFE disc dosemeters and 2-8 rad for the extruded ribbon dosemeters. A further study of this technique has revealed that by raising the temperature of the dosemeter during bleaching the threshold for re-estimated absorbed doses may be substantially reduced. The optimum temperature was found to be 80 degrees C and the practical threshold for the re-estimation of absorbed dose using a PTFE disc dosemeter was determined as 750 mrad.
