several significant events linked to loss of source control (source “jamming”) did occur during the use of gamma ray projectors. Nevertheless, and contrary to the previous years, the majority of these significant events involved inappropriate or prohibited actions by the operators leading to unnecessary exposure but without exceeding regulatory limits. Moreover, these actions complicate the subsequent operations necessary to restore a normal situation. ASN points out the obligation for all gamma ray projector users to obey the instructions applicable in the event of a situation of “source jamming” outside the projector, which consists during the emergency phase in immediately stopping any handling of the projector or its accessories, rapidly cordoning off the area to avoid any further exposure to ionising radiation and contacting the device supplier for assistance. ASN remains particularly attentive to the management of these events. The need to plan for an emergency organisation for managing such events was moreover recalled in the circular letter that ASN sent to the radiography professionals in 2021. Penal enforcement actions have already been proposed for serious breaches, and will continue to be so. 3.2 Industrial irradiators 3.2.1 The devices used Industrial irradiation is used for sterilising medical equipment, pharmaceutical or cosmetic products and for the conservation of foodstuffs. It is also used to voluntarily modify the properties of materials, such as for the hardening of polymers. These consumer product irradiation techniques can be authorised because, after being treated, these products display no residual artificial radioactivity (the products are sterilised by passing through radiation without themselves being “activated” by the treatment). Industrial irradiators often use cobalt-60 sources, whose activity can be very high and exceed 250,000 terabecquerels (TBq). Some of these facilities are classified as BNIs (see chapter 12). In many sectors, X‑ray generators are gradually replacing high-activity sealed sources for the irradiation of products (see point 1.3.1). GAMMA RADIOGRAPHY: SERIOUS ACCIDENTS ABROAD The number and consequences of gamma radiography accidents in France have remained limited since March 1979, when a worker had to have a leg amputated after having picked up a 518 GBq source of iridium-192 and put it in his pocket. This incident had led to a tightening of the regulations in effect at the time. This must not be taken for granted. ASN keeps a watchful eye on accidents occurring abroad which have sometimes had serious effects. Over the last few years, examples brought to ASN’s attention confirming the risks to which operators can be exposed as a result of inappropriate actions, include: ■ In 2022, in the United States, a team of three operators of a non-destructive testing company was performing gamma radiography work. One of the operators was close to the cobalt-60 source when it was ejected by his colleague who did not have direct visual contact with him. Given the very noisy environment of the worksite, the operator did not hear the alarm of his monitoring devices and was exposed to a dose of 55 millisieverts (mSv)for about one minute. ■ In 2022, in Belgium, a radiographer was exposed (14 mSv whole body, extremity dose not specified) to a selenium-75 source for a short period (60 to 90 seconds) when he tried to disconnect the device collimator while the source was still present in it. The alarm of his active dosimeter did not function because its battery was discharged; furthermore, the operator was not equipped with his radiation meter. It was the triggering of his assistant’s active dosimeter alarm when he approached the source that signalled the incident. ■ In 2022, in Hungary, an operator was exposed to about 134 mSv when handling the collimator and the guide tube, as the selenium-75 source was not retracted into the safe position in the projector. ■ In 2021, in the USA, an employee of a non-destructive testing company was exposed to a dose of 70 mSv (whole body) while carrying out gamma radiography exposures within a dedicated facility. The procedures in force at the time of this accident authorised the operator to be present inside the facility even when the source was in the irradiation position. An employee of another nondestructive testing company was exposed to a dose of 93 mSv (whole body) when manipulating a defective gamma radiography projector whose source was not in the safe position. These two events were rated level 2 on the INES scale. ■ In 2021, in Serbia, an iridium-192 source became detached from the remote control cable during an outdoor non-destructive test. The two operators did not check that the source had returned to the safe position at the end of the inspection and did not notice its absence until they got back to their company base. The source was found the next day after the intervention of a specialised laboratory. The two operators were exposed to doses of 451 mSv and 960 mSv; ■ In 2021, in Spain, an employee of a non-destructive testing company was exposed after entering a gamma radiography bunker when the iridium-192 source was not in the safe position (source jammed). The passive dosimeter of the first employee indicated a dose of about 70 mSv, and that of the second about 3 Sieverts (Sv). The event was rated level 2 on the INES scale. ■ In 2020, in the United States, a radiographer and two assistantradiographers performing nondestructive tests in an asphalt production unit were exposed to whole body doses of 636, 104 and 26 mSv respectively while attempting to reintroduce the source into the gamma ray projector after the guide tube had been crushed by a support which fell from a storage tank. The event was rated level 2 on the INES scale. ■ In 2019, in Spain, an employee of a non-destructive testing company was exposed to about 200 mSv (whole body) by entering a gamma radiography bunker when the iridium-192 source was not in the safe position. The door-opening slaving system for prohibiting access to the bunker during the emission of ionising radiation, did not function due to the failure of the dose rate measuring system. The event was rated level 2 on the INES scale. A similar accident happened the same year in Germany: two employees were exposed to 100 and 30 mSv respectively (whole body) when they entered a gamma radiography bunker when the iridium-192 source was not in the safe position and the radiological environment had not been checked. The event was rated level 2 on the INES scale. The data from before 2019 can be consulted in the previous issues of this annual report. The issues are available at asn.fr, under the headings “ASN informs”, “Publications”, “ASN’s annual reports”. 254 ASN Report on the state of nuclear safety and radiation protection in France in 2022 • 08 • Sources of ionising radiation and their industrial, veterinary and research applications 08
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