ivan p. salati de almeida director of radiation protection and nuclear safety brazilian nuclear...

Ivan P. Salati de Almeida

Director of Radiation Protection and Nuclear Safety

Brazilian Nuclear Energy National Commission- CNEN

September 2012

Small Scale Post-Accident Remediation

Senior’s Regulator Meeting

Session II - Specific Challenges in Implementing Remediation

BrasiliaGoiania

The accident of Goiania - Brazil

R.Janeiro

S.Paulo

Goiania-Brasilia=173 km

Goiania-S.Paulo=937 km

Goiania-R.Janeiro=810 km

Distances

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 13th,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 10th to 13th,1987: part of a teletherapy equipment with a caesium-137 source was removed from an abandoned building and opened, breaching the caesium capsule.

• September 13th to 28th: 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 28th to 29th: the accident was confirmed by a medical physicist and first actions were taken by local authorities.

• September 29th to 30th: 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

Monitoring people

Olympic Stadium (112,800 persons monitored)

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 = 8 Hazards in bone marrow = 4 Deaths = 4

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 km2 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 29th to December 24th 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

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 equipment headhead

equipment equipment headhead

Decontamination work

Assignment of contaminated areas

Criteria (0.5 Sv/h)

Decontamination work

– 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

Criteria for decontamination

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 m3 (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

• 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

Regional Center for Nuclear Sciences Information Building

Final Repository

The end

Thank you