[ RadSafe ] 1. official Belgian report on the Sterigenicsradiationaccident
Jose Julio Rozental
joseroze at netvision.net.il
Thu Apr 13 11:50:18 CDT 2006
Your question: "Why would the operator, a veteran of some 24 years, enter the room to initiate the startup procedure without a survey meter in hand? Our employees do not enter irradiation chambers without a direct reading/alarming dosimeter in addition to their survey meters, the latter are checked for audible signal and needle deflection prior to entry (with a check source stationed near the entrance)."
COMMENT:
I) "Why would the operator, a veteran of some 24 years, enter the room to initiate the startup procedure without a survey meter in hand?
A) This was not the first case that as generate the same question, many others have occurred previously. If you look at the IAEA documents on Radiological Accident, Starting from the first - The Radiological Accident in Goiania - you will find many similarities among accidents, including non compliance from experimented workers.
In the Radiological Accident in Goiania, the Judge in the court has asked to the physician "Why you, with large experience, left the source abandoned?" -- To the Medical Physicist, only employee, the judge asked Why you didn't communicate such situation to the Regulatory Authority? -- Both was penalized by the court.
In Similar practices the Sterigenic I can mention
(a) The Radiological Accident in USA June 1974:
Description of Circumstances:
An experienced operator received a whole body exposure of from 300 to
400 rems when he entered a cell where a 120,000-Curie cobalt 60 source
was in the unshielded position.
This entry resulted from several significant contributing causes which
included:
1. A radiation alarm circuit required by the license had been
deactivated. If operating it would have alerted the operator to an
unsafe condition.
2. The operator failed to perform a physical radiation survey as he
entered the cell.
3. The operator failed to follow approved pre-cell-entry operating
procedures, which required visual assurance that the source had
been returned to its shielded position.
4. The cell operator was unaware that the radiation alarm circuit had
been or could be deactivated.
---------------------------------------------------------------------------------------------------------------------------
(II) The Radiological Accident at The Irradiation Facility in Nesvizh, Belarus
In October 1991, a worker entered the exposure room of a large,
dry storage irradiator. The source was in an unshielded position, and the
worker received a fatal radiation dose.
However, on entering the facility the operator bypassed a number of safety features and left the controls in a position such that exposure was imminent.At some stage, the source rack became exposed and the operator was irradiated for about 1 minute. He suddenly felt unwell and then noticed the source rack in the irradiation position. The accident was quickly reported to the authorities and the operator was taken into medical care, first in Nesvizh and Minsk, and then for specialized treatment in Moscow. It was estimated that he had received a whole body dose of 11 Gy, with localized areas of up to 20 Gy. Despite intensive medical treatment, he died 113 days later. At the time of the accident the activity of the cobalt-60, source was 760 KCi.
The operator involved in the accident was a 34 year old man. He had a degree in engineering and was the most experienced operator at the plant, having commenced employment at the facility during its construction. Thus, he was completely familiar with the facility, the hazards and the safety systems. He was regarded as a skilled operator capable of dealing with operational problems and meeting production targets. It was estimated that he had received a whole body dose of 11 Gy, with localized areas of up to 20 Gy. Despite intensive medical treatment, he died 113 days later.
2) "Our employees do not enter irradiation chambers without a direct reading/alarming dosimeter in addition to their survey meters, the latter are checked for audible signal and needle deflection prior to entry (with a check source stationed near the entrance)."
As mentioned many non compliances, were made by experimented workers, if we read the IAEA publications on the accident, in the lessons learned they mention the necessity of good practices and systematic observations by the Installation Management of the routine work. One of the most important lessons in this direction is: Many Accidents have caught countries by surprise. Look another example with well trained workers: The Nuclear Accident in Tokaimura. Experimented workers have failed to follow written procedures of operational work.
----------------------------------------------
Finally to give an idea about the Radiological Accidents with fatalities and high exposure, look my paper Two Decades of Radiological Accidents Direct Causes, Roots Causes and Consequences
http://www.doaj.org/abstract?id=44227&toc=y or
http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-89132002000500018
Jose Julio Rozental joseroze at netvision.net.il Israel
----- Original Message -----
From: "NIXON, Grant" <Grant.NIXON at mdsinc.com>
To: <radsafe at radlab.nl>
Sent: Wednesday, April 12, 2006 11:22 PM
Subject: RE: [ RadSafe ] 1. official Belgian report on the Sterigenicsradiationaccident
> Of course, there are other questions.
>
> Why would the operator, a veteran of some 24 years, enter the room to initiate the startup procedure without a survey meter in hand? Our employees do not enter irradiation chambers without a direct reading/alarming dosimeter in addition to their survey meters, the latter are checked for audible signal and needle deflection prior to entry (with a check source stationed near the entrance).
>
> As a matter of practice, the source is always considered to be in the "irradiate position" before entry into an irradiation chamber. This is irrespective of control systems and alarms. In this case, the alarm system had been active prior to entry.
>
> The operator also failed to notice the source rack out of the pool.
>
> Otherwise intelligent people are capable of committing foolish acts when their minds are not properly engaged and focused on the hazards of the job. Interlocks and safety systems are great but they are no substitute. The right attitude, a culture of safety, and a healthy respect for the potential dangers of ionizing radiation must remain at the forefront of one's mind when on a job. This respect and presence of mind must persist and not fade with experience.
>
> Grant Nixon
>
> -----Original Message-----
> From: radsafe-bounces at radlab.nl [mailto:radsafe-bounces at radlab.nl] On Behalf Of Rainer.Facius at dlr.de
> Sent: Wednesday, April 12, 2006 3:07 PM
> To: radsafe at radlab.nl
> Subject: [ RadSafe ] 1. official Belgian report on the Sterigenics radiationaccident
>
> The Belgian Federal Agency for Nuclear Control (AFCN) responsible for the investigations on the accident has released its first communiqué on the Sterigenics radiation accident.
>
> http://www.fanc.fgov.be/fr/news_2006_04_11_dossier_streigenics.htm (20060412)
>
> (1) The dose estimate has been raised to between 4.4 to 4.8 Sv
>
> (2) No other person has unduly been exposed.
>
> (3) Instrumental to the Co-60 source not being in its home position was a defect in the control system for the hydraulic gear moving the source, leading to an "oscillatory and inopportune" movement of the source holder. "Interferences between the hydraulic systems for the two irradiation rooms" GAMIRR I and GAMIRR II are hypothesized to have triggered these oscillations.
>
> (4) No word why the ambient dose-rate meters inside GAMIRR II did not work or why the entrance was not interlocked as it should when the source is not in its home position.
>
> Rainer
>
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