Brazilian Industrial Radiography Accident: Reconstructive Dosimetry and Lessons Learned IAEA...

Brazilian Industrial Radiography Accident: Reconstructive Dosimetry and Lessons Learned

IAEA Technical Meeting on Radiation Safety in Industrial RadiographyVienna 23-27 June 2014

Technical Meeting on Radiation Safety in Industrial RadiographyTechnical Meeting on Radiation Safety in Industrial RadiographyIAEA – ViennaIAEA – Vienna

23 - 27 June 201423 - 27 June 2014

Dr. Francisco Cesar Augusto Da SilvaInstituto de Radioproteção e Dosimetria - IRD/CNEN

Brasil

Brazilian Industrial Radiography Accident: Brazilian Industrial Radiography Accident: Reconstructive Dosimetry and Lessons LearnedReconstructive Dosimetry and Lessons Learned



Nuclear and Radioactive Installations

Nuclear InstallationsNuclear Power Plant: 2 Nuclear Research Reator: 4Nuclear Mining and Milling: 2Fuel Cycle Industrial Complex : 2 unitsNavy Industrial Complex: 1 unit

CNEN Research Institutes: 5 units(radioisotopes production, cyclotron accelerator; industrial irradiator, gammagraphy source production, metrology laboratory,...)

Radioactive Installations: 1574Industry Area: 635Medical Area - Radiotherapy and Nuclear

Medicine: 680Research: 228 Service: 31

Medical X Ray Devices:100000

Brazilian Overview



Reference: CASEC/IRD/CNEN June 2014

7Calibration of

Equipment Laboratories

(1 SSDL)

12 Individual

Monitoring Laboratories

(Film Badge, TLD and OSL)

Approved Laboratories165000Radiation Workers

Medical Area: 75%

Industry, Research & Other Areas: 25%

Brazilian Overview



92 Installations (Companies)

Reference: CNEN´s Database – June 2014

276 Radiation Protection Officers

1700 Radiographers (Operators)

300 Gamma Devices with sources of 192Ir, 75Se, 60Co

Industrial Radiography

200 Daily On-site Radiographies

Brazilian Overview



CNEN Regulations

General Regulations:

NN-3.01-2014: BASIC SAFETY STANDARDS FOR RADIATION PROTECTION

NE-5.01-1988: SAFE TRANSPORT OF RADIOACTIVE MATERIAL

Specifics Regulations applied to Industrial Radiography:

Res 166-2014: Licensing Requirements for Radioactive Installations

NN-6.04-2013: Safety and Radiation Protection Requirements for Industrial Radiography Services

NE-3.02-1988: Requirements to Radiation Protection Services

NN-7.01-2013: Certification of Qualification for Radiation Protection Officer

CNENNational Commission of

Nuclear EnergyBrazilian Regulatory

Authority

Brazilian Overview



Relevant Radiological AccidentsEvents with severe injuries

Wrong emergency rescue procedure: a trainee operator held the source holder with his the hand.

1997 -192Ir - 1.62 TBq (43Ci)

2000 – 60Co - 2.11 TBq (57Ci)

Due to a procedure failure, during routine maintenance work of a cobalt device, an operator kept his left hand very close to the radioactive source, during approximately 30 seconds. Reference: GADE/IRD

Brazilian data include 5 serious radiological accidents affecting 7 radiation workers and 19 members of the public, resulting in the development of the Cutaneous Radiation Syndrome in hands and fingers.

A device was stolen from the transport vehicle and a truck driver found it. The radioactive source was removed and handled by members of the public.

1985 -192Ir - 0.88 TBq (23Ci)



The Radiological Accident – May 2000

An industrial gamma radiographer was performing routine exposures with a 60Co Gammamat apparatus (model TK100, Isotopen-Technik Dr. Sauerwein) containing a 2.11 TBq (57 Ci) source.

The operator was not bearing a personal monitor with alarm, and did no carry a survey meter.

At the end of the tasks, when he tried to detach the guide tube from the exposure container - unaware that the source was not in the secured position - he kept his left hand very close to the radioactive source, for approximately 30 seconds.

Noticing that it was impossible to detach the guide tube from the device, area monitoring was conducted, which showed that indeed the source was not in the secured position. The source was jammed in the internal tube near the guide tube.



The effective and absorbed dose estimations of the Brazilian accident were performed using the following methods:

Reconstructive Dosimetry Methods

Physical Method by film badge individual monitor and a simulator of a left hand with thermoluminescent dosimeters;

Biological Dosimetry Method by cytogenetic analysis

Computational Method by a Brazilian Monte Carlo calculation code, named “Visual Monte Carlo –VMC”, with human body voxel simulator

Clinical Observation of the signs of the lesion, particularly in the fingers and hand with radiation-induced necrosis.



Physical and Computacional Methods

The dose reconstruction used for assessment of the distribution of doses on the worker’s left hand and organs were made using two methods: physical and computational techniques.

For the first technique a physical hand simulator was built and it was also used the Alderson Rando phantom for organs doses.

The computational method was performed using microcomputer software for external dose calculations, named ‘Visual Monte-Carlo - VMC’, together with a hand voxel simulator and Alderson Rando phantom.

The values obtained through both methods for the distribution of absorbed doses on the operator’s left hand and organs doses were compared.

Computational Simulation to Hand Dose

Computational Simulation to Organ Dose



Effective dose of 88.1 mSv using film badge individual monitor.

Effective dose of 60 mGy based on observation of none dicentrics observed at one thousand cells scored using the cytogenetic analysis.

Results of Dose Estimations

Absorbed doses of 7.41 Gy and 17.56 Gy in the thumb and index fingers using a left hand physical simulator.

Absorbed doses between 10 Gy and 20 Gy in the thumb and index fingers based on the clinical observation of oedema and erythema in operator`s hands after 8 days; appearance of blisters on his left hand, mainly on the thumb and index finger after 21 days and dry desquamation on both hands after 23 days.

Absorbed doses of 7.80 Gy and 15.90 Gy in the thumb and index fingers using Visual Monte Carlo computational dosimetry method

Absorbed doses (mGy)



Erythema, oedema and blisters on the operator’s hands (Day 30).

Regulatory Authority Enforcement

Formal reprimand to the Company’s Director.

Temporary suspension of the facility operation.

Restriction of using of the 60Co gamma device.

Permanent removal of the operator from radiation job.

Main Causes Operator Consequences The radioactive source had stuck inside the exposure container, but not in the secured position due to corrosion inside the container and poor maintenance of the equipment.

The operator was not carrying his personal alarm.

The operator did not perform the proper and necessary radiation monitoring of the gamma device with a portable radiation monitor.

The operator failed to follow the safety procedures.



To assess periodically the gamma device internal channel with an industrial borescope.

To perform periodically the smear test inside the gamma device internal channel.

To provide the use of individual monitor with audible and vibrating alarms for all operators permanently.

To maintain continuous education and training in radiation protection and safety in industrial radiography.

Lessons Learned



Education and Training in Radiation Protection and Safety in Industrial Radiography

Lessons Learned



Evaluation of Eye Lens Doses on Industrial Gamma Radiography Workers using Monte

Carlo Method

Portable Gamma Devices

Radioactive Source:Iridium-192 – gamma

radiationActivity Max. 3.7 TBq


Lessons Learned



Safety Evaluation of Gamma Radiography Devices

Portable Gamma Devices

Radioactive Source:Iridium-192 – gamma radiationActivity Max. 3.7 TBq

Industrial radiography is used throughout the world to examine the structural integrity of materials in a non-destructive manner.

In Industrial Radiography were recorded more than 40 radiological accidents involving 37 workers, 110 members of public and 12 deaths, around the world.


Lessons Learned




Lessons Learned

ANALYSIS OF RADIOLOGICAL ACCIDENTS IN INDUSTRIAL

RADIOGRAPHY

LESSONS LESSONS IDENTIFIED LESSONSLEARNED

ANALYSIS OF RADIOLOGICAL ACCIDENTS IN INDUSTRIAL

RADIOGRAPHY

LESSONS LESSONS IDENTIFIED LESSONSLEARNED



Main Objectives: • To investigate all radiation overexposure cases recorded by personnel dosimetry.• To evaluate the worker dose and, if necessary, to give information for medical actions.• To find out the real causes of the event and to emit recommendations to avoid other radiation overexposure cases.• To modify or to ratify the exposure recorded on the personnel monitoring register.• To publish scientific information about all radiation overexposure cases.• To maintain a database of radiation overexposure cases.

Radiation Overexposure Analysis Group

Main Activities:• Technical and scientific analysis of the accident.• Dose investigation and accident reconstruction• Dose calculation• Cytogenetic dosimetry• Technical report with recommendations to avoid other radiation overexposure cases

From 1985 to 2012, 560 persons were investigated of having been overexposed.



Francisco Cesar Augusto Da [email protected] - Brasil

Brazilian Industrial Radiography Accident: Reconstructive Dosimetry and Lessons Learned IAEA...

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