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Safety Issues in the Management of Industrial Radiography
Roger Griffiths,Inspection and Integrity Manager, BP Refinery (Bulwer Island) Ltd.
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This paper questions the common assumption that an industrial radiographer has sole responsibility for job safety, pointing out that the owner, or supervisor in charge of the overall work, has overall responsibility. Management models are proposed in which the owner or supervisor takes a more active role than has usually been the case. It also discusses a radioisotope retrieval incident and recommends a revision to gamma camera designs, proposing that the lock should be fitted to the delivery port not the control port.
Keywords:Radiography, Safety, Management, Procedure, Camera, Lock
Radiography on an industrial site poses a number of safety challenges that are frequently not adequately addressed by the overall management of the work of which radiography forms a small, but often critical, part. The BP refinery at Bulwer Island, in Brisbane, has always included radiography as part of its in-house inspection capability, and also uses contract radiographers for project work. We are therefore in a situation, possibly unique, where we see radiography from the perspectives of both service provider and customer.
The first goal of this paper is to discuss who should be the appropriate person to take prime responsibility for safety when radiography is performed. The second is to briefly re-visit an event where a source had to be retrieved from a difficult location. Some lessons learnt at that time have been published (see references 1 and 2), and were largely incorporated into the Australian code (ref. 3). More importantly, the experience strongly suggests that some developments in gamma camera design are wrong.
Over the course of many years we have experienced incidents which have resulted in the potential for inadvertent exposure to non-radiography personnel when contractors have been performing radiography. It is unthinkable to suppose that incidents such as these have not occurred on many, perhaps all, similar sites. However the impression gained from discussion with personnel from other sites and contract radiographers is that similar incidents are not reported elsewhere, despite little or nothing having been done specifically to address the issues, either by the contract companies or by their customers. It is our belief that the reason for this is simply that, as radiographers ourselves, we are far more aware of the issues than other customers. We are therefore well qualified to comment on the situation and to propose remedies.
The code (ref.3) refers to three types of radiography site: fully enclosed, partially enclosed and open sites. Enclosed sites are essentially purpose built and are not the subject of this paper, although the principles outlined may apply. Discussion will centre around open radiography sites in two situations: in a processing complex and in a client's workshop.
2.1 Radiography in a processing complex:
A processing complex such as an oil refinery or petrochemical plant is usually laid out around a pipe rack, which extends the length of the plant, usually with branches running to connect different sections of the plant. Process vessels such as heat exchangers and fractionation columns are aligned adjacent to the pipe racks, and pumps are lined up along both sides but under the pipe racks, leaving a clear pathway under the racks for access.
The layout means that a lot of equipment is located alongside the pipe racks, and the 'geography' of such plant is very convoluted. During maintenance or construction the situation is exacerbated by the addition of scaffolding, welding machines, dismantled equipment, tool boxes, temporary piping, hoses and cables. Work can be performed anywhere in the plant, at any elevation, inside pressure equipment and ducts. A large number of trades may be involved including fitters, welders, electricians, instrument mechanics, riggers and scaffolders. All these may report to different supervisors, and there may be several different contractor teams supplying tradesmen of each type, so in a given area there may be 20 or more teams each with their own supervisor.
When a contract radiographer is employed to work in such an environment a typical approach is to assume the radiographer has full responsibility for the safety of his work. The radiographer may be required to inspect a weld over a half hour lunch break, for example. He is expected, with one assistant, to arrive no more than an hour before the job is due to start, locate the weld to be inspected, obtain his permits and set his equipment up ready on site. At the start of the break work crews leave the site. The radiographer and his assistant are then expected to rope off and post warning signs around a predetermined area which can be 50 or 60 metres across, assure themselves that the enclosed area is in fact vacated, take three radiographs on the weld, remove the rope and signs and be finished by the time the work crews re-appear. This is clearly impossible. It is only just possible to do the work necessary to perform the inspection, and simply not possible for two people to absolutely ensure that the area has been vacated, in that time. People may be working inside pressure vessels or ductwork, up in pipe racks or on or in other equipment above or around the radiography site. The complex 'geography' of a site can change from day to day as plant is built or demolished, as equipment is opened up or closed, as scaffolds are erected and dismantled. Furthermore there may be ways of inadvertently climbing over the radiation barrier rope, by climbing up on equipment which is outside the barrier, across an elevated walkway, pipe rack, scaffold or duct, and emerge in the middle of the radiation zone. It must be born in mind that in addition to the above trades there are activities such as plant inspection, or other activities of engineers, supervisors and tradesmen, that are best done during a quiet time. The radiographer simply does not have the means to adequately broadcast his intended activities, even in the unlikely event that he manages to identify and talk with all work supervisors in the area.
Taken at face value the code (ref. 3) does not address this issue. It places responsibility only on the radiographer. To be effective this would imply that the radiographer would need to become involved at a much earlier stage to investigate and explore the work site, to discuss with his client's management what activities will be taking place around the time that radiography is to be performed and to communicate with the supervisors for every work team that may be in the area. In many instances it will still then be necessary to provide additional assistance to ensure that the area has been vacated before the source is exposed.
The objection to this approach is partially one of cost: the research required to prepare for the work would add considerably to the time spent on the site. Where the radiography contractor is to provide additional manpower to check the area is clear costs would escalate further. But the main objection is that this approach is not practical. It is not reasonable to require a radiographer, who may only be there to perform a 30 minute task, to get to grips with the intricacies of the situation.
An alternative way is to acknowledge that prime responsibility for job safety lies with the plant manager or owner, delegated to the supervisor who has overall control of the job. This is an over-riding provision of the Queensland workplace health and safety legislation. Equivalent legislation in other states of Australia and in many other countries is similar. Indeed this is most appropriate: the owner's management team is in overall control of the work, has the best knowledge of the plant layout, the objectives of the work being undertaken and the means by which it will be performed. On the day that radiography is performed the supervisor's responsibility for safety would amount to little more than ensuring the area is vacated. He would have ample opportunity, at daily meetings etc., to keep managers, engineers and supervisors of other work in the area informed, and if necessary can arrange for assistance with vacating the area. The radiographer can focus on his own work, his prime responsibility then resting with the direct requirements of the code including confirming with the supervisor that the area has been vacated.
A further alternative often proposed is to restrict radiography to the night shift. When there is a large amount of radiography to be done this may be the only way to achieve it without disrupting the work schedule, but that is another issue. While this can help with safety caution is still necessary. Even when the plant is said to have been vacated the responsibility to assure that it is in fact vacated is unchanged. Even when others have gone there still may be some work continuing by plant inspectors and engineers or even people hiding and asleep! The urgency may be reduced compared to a lunch time shot, but the need for assurance is not. There are fewer people available to assist, and those who are on site at the end of a late shift may not be in a co-operative frame of mind.
At this refinery we have a procedure (appendix 1) that clearly delegates prime responsibility for safety to the job supervisor. There was significant resistance to the concept at first, but this was based on poor appreciation of the practicality of leaving it to the radiographer. Where the job supervisor is a contractor the response is mixed. However if all sites had the same requirement (or, to put it another way, responded to their obligations in this regard under the workplace health and safety legislation or equivalent) it should quickly become just a part of the job.
It is recommended that the code (ref. 3) be amended by including a reference to the over-riding responsibility of the owner in assuring that the work is conducted safely.
2.2 Radiography in a client's workshop:
Much of the background for this section comes not from direct experience but from conversations with contract radiographers. The following brief summary is intended only to give a flavour of the issue.
It is a frequent requirement for radiography to be performed in a client's workshop. The radiographer's work is often seen to be an imposition. There is little understanding of why the shop must be vacated. It would seem that in extreme cases reactions can include physical violence. However the issue here does not stop at vacating the workshop. Quite a number of contract radiographers have been surprised at the suggestion that they should enquire as to what lies behind the back wall of the workshop. It may be the next door business, or even the crib-room for the client's workshop, the workmen who have just vacated the shop now seated in a row half a metre away from where the source is exposed with only a radiation-transparent block wall for shielding.
I have suggested to various radiography contractors that they might prepare an information sheet which could help resolve these issues by encouraging effective communication and assisting their clients to prepare for the work. I am not aware that this has been done, and perhaps there are compelling arguments (legal and political) against the idea, but I have attached a suggested document (appendix 2) which may be a useful start.
Many years ago we encountered a situation where a radioisotope had to be retrieved from the top of a 36m (120 ft) high distillation column. This has been the subject of papers delivered to the Australian Radiation Protection Society [1] and AINDT [2] conferences, and a presentation was made to a radiation safety officers users group meeting, so the situation will not be discussed in detail here. Subsequently much of what was learned in that event was incorporated in the code (ref. 3). The contribution to the code related largely to the requirement to plan the action to be taken. A point that was not incorporated in the code related to the fact that at the time we had no idea of what had actually occurred. Nevertheless we decided exactly what we would do and, despite enormous misgivings that anything would be achieved, carried this out exactly until an opportunity to resolve the situation presented itself. (For those who look up the paper note the erratum in a following edition). Had this not happened we would have had no option but to retreat and consider alternative courses of action.
It may be worth mentioning that the paper [1] was acknowledged verbally as contributing to the code but was not referenced in it. Had it been referenced much of the content would have been brought to life for anyone who looked it up!
The situation was resolved when it was found that the problem lay in the winding cable mechanism. This was then disconnected from the back of the camera and the radioisotope returned to its storage position by pulling directly on the cable. This process would have been far more difficult, and certainly would have taken far longer, with more modern equipment. The equipment concerned was an Iriditron camera, where the lock simply locked the end of the pigtail at the control port. This has now been replaced with an Amertest 660 B. This has a lock that acts on the winding mechanism in such a way that the winding mechanism cannot be removed from the control port unless the pigtail is in the stored position. In the situation we encountered it would have taken significant time to cut through the winder cable sheath in order to recover the radioisotope. We would have had to get additional tools, which would have involved making the return trip down and back up 120 feet of cat ladder, fully in the radiation beam and with no option to choose a shielded route. But the question is, why is the control port locked at all? There is no reasonable way in which the pigtail can emerge from this end. Locking the winder does not ensure that the delivery tube is in place, and there are tales of radiographers (perhaps exhausted during a 3am shift!) failing to connect the delivery tube before winding out. It would make far more sense to place the lock at the delivery port. If it is interlocked with the delivery tube the source cannot be wound out until everything is connected. Manufacturers: please note!
(It is appreciated that an additional simple mechanism would be required to prevent the pigtail from going forward if the delivery tube is attached before the winding cable, and that this should not prevent it coming back.)
The focus on safety issues in the public eye, the press and legislation is ever increasing, and the potential consequences of even a minor incident involving radiation are rising proportionally. The incidents that have occurred on our site strongly suggest that similar un-reported incidents have occurred elsewhere. Changes in attitude and action are needed.
It is not suggested that what has been proposed above is the only possible solution. The essential points are for the management of sites where radiography is performed:
The situation with the gamma camera lock (section 3) is, in my view, that the gamma camera lock must be installed on the delivery port instead of the control port.
Note that References [1] and [2] cover essentially the same material.
Procedure for radiography performed in the refinery by contractors
1. Purpose
To state requirements for contractors performing radiography in the refinery and for all supervisors or engineers who utilise their services.
2.Scope
This procedure applies to all radiography performed by contractors in the refinery, and gives guidance for radiography performed 'in house' and for other use of ionising radiation performed 'in house' or by contractors.
3. Definitions
Contract Radiographer: A radiographer not working under the direct supervision of the Refinery Inspection Department.
Supervisor: The person in direct control of the job of which radiography is a part. This would typically be a Refinery or Contract engineer, a refinery maintenance supervisor or a mechanical contractor's supervisor.
4. Procedure
The information given here is necessarily very general. It is strongly advised that details of the work are discussed with us well in advance. It is emphasised that while the radiographer is responsible for the safe use of his equipment, you have overall responsibility for safety.
What is radiography, and why is safety an issue?
Radiography involves the use of a beam of radiation to create an image which shows the internal structure of an otherwise opaque object. The radiation can damage living tissue and precautions must be taken to ensure no-one is damaged by the process.
How can you help?
We need to know what components and what parts of each component are to be inspected by radiography, the material it is made of and its thickness, and what acceptance standard applies. If radiography is not for weld inspection we need to discuss details of what you want to achieve.
The radiographer will need to have sufficient access to both sides of the components.
An area around the work site will need to be vacated of all personnel. This area may be several tens of metres across depending on the situation. You should plan your work for the day so that this can occur with minimum disruption.
Where radiography is to be performed within several tens of metres of a wall (or ceiling or floor with occupiable space above or below, or any obstruction to view), the radiographer must be assured that there is no possibility of anyone being behind it while the radiation beam is active. Concrete blocks and other building materials offer very little shielding from the radiation used. Particular care must be taken where a wall is on a property alignment, and in such an instance it may be necessary to make suitable arrangements with your neighbours in advance. Where the adjacent property is public land, or where public land is within a few tens of metres of the job, it may be necessary to make arrangements with local authorities.
Each situation will be different, and in many instances there may be a way around a particular problem. For example the radiation beam can often be mostly directed away from a sensitive area, but this will depend on the geometry, size and mobility of the component and the nature of the inspection.
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