Transcript I. Salati, Brazil - Nuclear Safety and Security
Senior’s Regulator Meeting Session II - Specific Challenges in Implementing Remediation Small Scale Post-Accident Remediation Ivan P. Salati de Almeida Director of Radiation Protection and Nuclear Safety Brazilian Nuclear Energy National Commission- CNEN
September 2012
The accident of Goiania - Brazil Distances
Goiania-Brasilia=173 km Goiania-S.Paulo=937 km Goiania-R.Janeiro=810 km Goiania Brasilia R.Janeiro
S.Paulo
Location
• City: Goiania (Capital of the State of Goias) • Population: ~1.000.000 inhabitants (at the time of the accident) • Teletherapy equipment with Cs-137 source • Day of the accident: September 13 th ,1987
Impacted area
CS-137 source characteristics
• • • • • Source activity (Sept/87): 1375 Ci (50.9 TBq) Chemical composition: caesium chloride (CsCl) Physical condition: compacted powder Mass CsCl: 93 g Mass Cs-137: 19.3 g
• • • •
Chronology
September 10 th to 13 th ,1987: part of a teletherapy equipment with a caesium-137 source was removed from an abandoned building and opened, breaching the caesium capsule.
September 13 th to 28 th : the Cs-137 was distributed to other people and was spread through other places in the city. Several people were hospitalized with symptoms of high doses irradiation.
September 28 th to 29 th : the accident was confirmed by a medical physicist and first actions were taken by local authorities.
September 29 th to 30 th : CNEN was notified and sent experts to Goiania.
Main issues to be dealt with in the accident
• • • • • • People monitoring and assessment of environmental contamination Medical care for victims (irradiated and contaminated) Re-establishment of the source control Decontamination of the places Interim storage for the waste generated Definition and construction of a repository
Olympic Stadium (112,800 persons monitored) Monitoring people
Data from the accident
Monitored persons = 112,800 Contaminated persons =271 •
clothes and shoes = 120
•
body contamination = 151
People with deterministic hazards = 28 Victims hospitalized= 20 Syndrome of acute radiation = Hazards in bone marrow = 4 Deaths = 4 8
Main contamination foci
Data from the accident
7 main contaminated places 42 additional contaminated places 85 contaminated houses; 7 demolished 50 vehicles decontaminated Aerial survey with helicopter equipped with radiation detector (67 km 2 monitored) Terrestrial survey with a car equipped with radiation detector
Data from the accident
Equipment: 55 dose rate meters, 23 contamination monitors 450 dosimetric pens Professionals involved: 250 technical staff 300 support staff Time First period: September 29 th to December 24 th 1987 Second period: January to end of March 1988
The main piece of the source 0.4 Sv/h at 1m (~120 Ci) Emergency shielding
Decontamination work Site isolated for decontamination
Decontamination work
57th Street Place where the source was opened
Decontamination work
House and land contaminated Dose rate 1,1 Gy/h at 1m
Decontamination work
Decontamination work
Decontamination work equipment head
Decontamination work
Assignment of contaminated areas Criteria (0.5
Sv/h)
Criteria for decontamination
– 5 mSv first year – 1 mSv/y dose for the whole life – Critical path for exposition: • Gama exposition inside home • Gama exposition outside home • Internal dose due to inalation and ingestion of fruits, vegetables, domestic animals
Remediation actions
• Part of the soil was removed and covered with concrete • Part of the soil was removed and substituted with non contaminated soil Contaminated trees were cut down
Waste resulted from the accident
• • • • • 3,500 m 3 (6,000 Ton.) 1,343 metallic boxes 4,223 drums (200 liter each) 10 maritime containers 8 Concrete cylinders VBA type
Interim storage of waste
Interim storage of waste
Interim storage of waste
Final Repository
•
Final Repository
Deposit 1 (common waste < 90 years) Store about 40% of waste (very low activity).
• • Deposit 2 ( 300 years) Dimensions: – Wall thickness: 25 cm – Basis surface distance from the soil level: 80 cm – Length: 54 m – Width: 14 m – Height: 4 m
Final Repository
Final Repository
Final Repository
Final Repository
Final Repository
Final Repository
Final Repository
Regional Center for Nuclear Sciences Information Building