[ RadSafe ] 1. official Belgian report on the Sterigenics radiationaccident

[NIXON, Grant]

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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