Goiânia accident
636913
221606628
2008-06-25T07:24:52Z
Anyeverybody
4687125
/* Nature of the source */
The '''Goiânia accident''' was an incident of [[radioactive contamination]] in central [[Brazil]] that killed several people and injured many others. On [[September 13]], [[1987]], an old [[Ionizing radiation#Human-made radiation sources|radiation source]] was scavenged from an abandoned hospital in [[Goiânia]], the capital of the central [[States of Brazil|Brazilian state]] of [[Goiás]]. It was subsequently handled by several people and caused serious radioactive contamination, resulting in a number of deaths.
==Nature of the source==
The object was a small, highly [[radioactive decay|radioactive]] thimble of [[caesium chloride]] (a caesium salt made with a [[radioactive isotope|radioisotope]] of [[Caesium-137|caesium]]) encased in a shielding canister made of [[lead]] and [[steel]] with an [[iridium]] window. The source was positioned in a container of the wheel type, where the wheel turns inside the casing to move the source between the storage and irradiation positions.
[[Image:GoiâniaRadiationsource.gif|thumb|400px|centre|A wheel type radiotherapy device which has a long [[collimator]] that makes the beam of radiation narrow. The radioactive source is the blue square and the gamma rays are represented by blue light]]
{| class="wikitable" style="cellpadding: 1%; float: right;"
|+ Comparison of radioactivities
|-
| colspan="2" |
! [[Becquerel#SI multiples|TBq]]
|-
| rowspan=5 valign="center" |
Goiânia<br />
source
|1971
|align="right" |74
|-
|when stolen (1987)
|align="right" |50.9
|-
|recovered
|align="right" |44
|-
|unrecovered (c. 1987)
|align="right" |7
|-
|unrecovered (c. 2007)
|align="right" |4.4
|-
| colspan="2" | smoke detector
|align="right" | 0.000000037
|-
|}
The source contained 74 [[Becquerel|terabecquerels]] (TBq) in 1971. The [[International Atomic Energy Agency]] (IAEA) describes the container—51 [[millimeter]]s (2 inches) in diameter and 48 millimeters (1.8 inches) long—as an “international standard capsule.” The specific activity of the active solid was about 814 [[Becquerel|TBq]]·kg<sup>-1</sup> of [[Caesium-137|Caesium 137]] ([[half life]] of 30 years). The dose rate at one meter from the source was 4.56 [[Gray (unit)|gray]] per hour (456 rad·hr<sup>−1</sup>). While the serial number of the device was unknown, thus hindering definitive identification, the device was thought to be made in the [[United States]] at [[Oak Ridge National Laboratory]] and was used as a radiation source for [[radiation therapy]] at the Goiânia hospital.<ref name = iaea>{{cite book | publisher = [[IAEA]] | title = The Radiological Accident in Goiânia | date = 16 Sep 1998 | isbn = 92-0-129088-8 | url = http://www-pub.iaea.org/MTCD/publications/PubDetAR.asp?pubId=3684}}</ref>
The IAEA document indicates that:
* The dose rate due to external irradiation from uniform contamination of the ground by <sup>137</sup>Cs is 1.6{{e|-12}} Sv·h<sup>−1</sup>·Bq<sup>−1</sup>·m³.
* The internal dose for ingestion is 1.2{{e|-8}} Sv·Bq<sup>−1</sup>
* The internal dose for inhalation is 8.7{{e|-9}} Sv·Bq<sup>−1</sup>
The IAEA states that the source contained 50.9 TBq (1375 [[Curie|Ci]]) when it was stolen, and that about 44 TBq (1200 Ci, 87%) of radioactivity has been recovered during the clean up operation. This means that 7 TBq remained in the environment; it will have decayed to about 4.4 TBq by 2007.
For comparison, the average modern [[smoke detector]] contains about 37 kBq (1 μCi) of [[Americium-241|<sup>241</sup>Am]].<ref>{{cite web | publisher = [[U. S. Environmental Protection Agency]] | url = http://www.epa.gov/radiation/sources/smoke_alarm.html | accessdate = 2007-11-04 | title = Smoke Detectors & Radiation}}</ref>
==Events==
=== Scavenging of the source ===
When Goiânia’s Instituto Goiano de Radioterapia (IGR)<ref name = iaea/> clinic was abandoned in 1985, the caesium-137 based teletherapy equipment was left behind. Over the following years, many [[squatter]]s and scavengers entered the building. Eventually, on [[September 13]], [[1987]], two people—Roberto dos Santos and Wagner Mota—came across the [[radioactivity|radioactive]] teletherapy head and took it with them in a wheelbarrow. They partly dismantled the equipment, subjecting themselves to external [[gamma radiation]], which caused localized [[Radiation burn|burns]] to their bodies; one later had to have an arm [[amputation|amputated]].
=== The source is opened ===
The two men attempted to further open the casing, but failed. They did, however, break the iridium window which allowed them to see the caesium chloride emitting a deep blue light. The exact mechanism by which the light was generated was not known at the time the IAEA report was written. The light is thought to be either [[fluorescence]] or [[Čerenkov radiation]] associated with the absorption of moisture by the source. Similar blue light was observed at Oak Ridge during the disencapsulation of a <sup>137</sup>Cs source in 1988.
=== The source is sold as scrap ===
Roberto dos Santos and Wagner Mota sold the object to a [[Wrecking yard|junkyard]] owner—Devair Alves Ferreira (radiation dosage 7.0 [[Gray (unit)|Gy]], survived)—who intended to make a ring for his wife out of the strange and beautiful blue material.
The sale to the junkyard owner led to many more people becoming contaminated:
*Junkyard workers hammered open the lead casing. Two of them died later of [[radiation poisoning]] (doses of 4.5 and 5.3 Gy, respectively).
*Devair Alves Ferreira’s brother Ivo scraped dust out of the source, spreading some of it on the floor of his house. His 6-year-old daughter, Leide das Neves Ferreira, later ate while sitting on the floor, absorbing some of the radioactive material (1.0 GBq, total dose 6.0 Gy). She was also fascinated by the blue-glow of the powder, applied it to her body and showed it off to her mother. When an international team arrived to treat her, she was confined to an isolated room in the hospital because the hospital staff were afraid to go near her. She died a month later ([[23 October]]) and was buried in a lead coffin, sealed with concrete.
*Several people who visited the home came into contact with the dust and spread it around the local neighborhood and to other towns nearby.
*Another brother of the junkyard owner used the dust to paint a blue cross on his skin. He also contaminated the animals at his farm, several of which died.
The junkyard owner’s wife, Maria Gabriela Ferreira (dosage 5.7 Gy), was the first to notice that many people around her had become severely sick all at the same time. She first suspected the culprit was a beverage they had shared, but an analysis of the juice showed nothing untoward. Her mother came and visited her to nurse her, getting a dose of 4.3 Gy and an intake of 10 MBq (270 µCi).
On [[September 25]], Devair Alves Ferreira sold the scrap metal to another scrapyard.
=== The source is understood to be dangerous ===
On [[September 28]] (15 days after the item was found) Maria finally suspected the scrap metal to be the cause. She took the remains of the source by bus in a plastic bag to a hospital, and the physician there rightly suspected that it was dangerous. He placed it in his garden on a chair to increase the distance between himself and the object. Because the remains of the source were kept in a plastic bag, the level of contamination at the hospital was low. The IAEA report suggests that 90% of the radioactivity originally in the source had escaped from it by this point.
A reconstruction of the bus cabin was created at a later time, and it is estimated that a hypothetical passenger who remained in the worst possible location for the entire bus trip (15 minutes) would have suffered a dose of less than 0.3 [[Sievert|Sv]] to the legs. This dose would not cause any injury or [[radiation poisoning|acute radiation syndrome]]. If this hypothetical passenger had been separated by 2.7 meters from the source, then the leg dose would decline to 0.04 Sv. While these prospective leg doses are larger than the normal organ limits for the general public, they are unlikely to cause serious harm in either the short or long term.
=== The source's radioactivity is detected ===
In the morning of [[September 29]] a visiting medical physicist (named WF in the IAEA report) used a [[scintillation counter]] borrowed from [[NUCLEP|NUCLEBRAS]] (a national government agency which is involved in the [[nuclear fuel]] cycle, including searching for uranium ore) to confirm the presence of radioactivity. The accident response started that evening. Maria, the wife of the scrap metal yard owner, died a month later ([[23 October]]) from the effects of the radiation.
== Health outcomes ==
=== The most contaminated people ===
The outcomes for the 46 most contaminated people are shown in the bar chart below. Several people survived high doses of radiation. This is thought in some cases to be because the [[Dose fractionation|dose was fractionated]]. Given time, the body's repair mechanisms will reverse cell damage caused by radiation. If the dose is spread over a long time period these mechanisms can ameliorate the effects of radiation poisoning.
[[Image:brazilcesiumhuman.png|center|600px|This is a barchart showing the outcome for the 46 most contaminated people for whom a dose estimate has been made. The people are divided into seven groups according to dose.]]
=== Other affected persons ===
Afterwards, about 100,000 people were examined for radioactive contamination; 244 were found to have significant levels of radioactive material in or on their body. Of this group 129 persons had internal contamination. The majority of the internally contaminated persons only suffered small doses (< 50 mSv, less than a 1 in 400 risk of getting cancer as a result).
1000 persons were identified as having suffered a dose which was greater than one year of [[background radiation]]; it is thought that 97% of these people had a dose of between 10 and 200 mSv (between a 1 in 2000 and a 1 in 100 risk of developing cancer as a result).
== Legal matters ==
In light of the deaths caused, the three doctors who had owned and run the hospital were charged with [[criminal negligence]]. The main cause of this incident was the severe negligence of the former hospital management who left behind such a dangerous item. The accident demonstrated the importance of keeping an inventory and monitoring of all strong radiation sources by public authorities, which now is legally required in many countries.
==Cleanup==
===Objects and places===
[[Topsoil]] had to be removed from several sites, and several houses were demolished. All the objects from within those houses were removed and examined. Those which were found to be free of radioactivity were wrapped in plastic bags, while those which were contaminated were either [[decontamination|decontaminated]] or disposed of as waste. In industry, the choice between decontaminating or disposing objects is based only on the [[Value (economics)|economic value]] of the object and the ease of [[decontamination]]. The IAEA recognized in this case, however, that to reduce the [[Psychological trauma|psychological impact]] of the event, greater effort should be taken to clean up items of personal value, such as [[jewelry]] and [[photographs]]. It is not clear from the IAEA report to what degree this was practiced.
=== Means and methods ===
After the houses were emptied, vacuum cleaners were used to remove dust before the surfaces and plumbing were examined for radioactivity. Painted surfaces could be scraped, while floors were treated with acid and [[Prussian blue]] mixtures. Roofs were vacuumed and hosed but two houses had to have their roofs removed. The waste from the clean up was moved out of the city to a remote place for storage.
[[Potassium]] [[alum]] dissolved in [[hydrochloric acid]] was used on clay, cement, soil and roofs. Caesium has a high affinity for many clays.
Organic solvents, followed by potassium alum dissolved in hydrochloric acid, were used to treat waxed/greased floors and tables. [[Sodium hydroxide]] solutions, also followed by dissolved potassium alum, were used to treat synthetic floors, machines and typewriters.
[[Prussian blue]] was used to internally decontaminate many humans. The urine was treated with [[ion exchange resin]] to compact the waste for ease of storage.
=== Recovery considerations ===
The clean up operation was much harder for this event than it could have been because the source was opened, and the fact that the active material was [[water]] [[soluble]]. A sealed source need only be picked up, placed in a [[lead]] pot and transported to the [[radioactive waste]] storage. In the recovery of lost sources, the [[IAEA]] recommends careful planning and using a [[crane (machine)|crane]] or other device to place shielding (such as pallet of [[bricks]] or a [[concrete]] block) near the source to protect recovery workers.
==Related==
It is possible to decontaminate high value [[scrap metal]]s, but this is best done long before the [[Radioactive scrap metal|contaminated metal]] goes to a scrap yard.<ref>http://mfnl.xjtu.edu.cn/gov-doe-netl/products/em/IndUnivProg/pdf/234.pdf</ref><ref>http://www.earthvision.net/industryprograms/pdfs/dd/30170.pdf</ref>
==See also==
* [[List of civilian radiation accidents]]
* [[Three Mile Island accident]]
* [[Chernobyl accident]]
* [[Windscale fire]]
* [[Nuclear and radiation accidents]]
* [[Radioactive waste]]
==References==
<references/>
==External links==
* [http://www.iaea.org/Publications/Magazines/Bulletin/Bull472/pdfs/srs_toolkit.pdf Similar accidents over the world] (short overview)
* [http://arts.bev.net/roperldavid/GRI.htm The Goiânia Radiation Incident]
{{DEFAULTSORT:Goiania accident}}
[[Category:Disasters in Brazil]]
[[Category:1987 disasters]]
[[Category:1987 in Brazil]]
[[Category:Nuclear accidents]]
[[Category:Radioactive waste]]
[[Category:Waste disposal incidents]]
[[Category:Caesium]]
[[Category:Goiânia]]
[[de:Goiânia-Unfall]]
[[pl:Skażenie w Goiânii]]
[[pt:Acidente radiológico de Goiânia]]