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Radiation Protection Adviser

Issue 7 May 1995

CONTENTS


Introduction

Welcome to the seventh edition of the newsletter. This issue includes three articles where we would particularly welcome your views for future publication - comments should reach me before the end of July. All items we include are cleared with the authors before publication.

We have made new distribution arrangements for this issue; please let me know if you had trouble in getting a copy.

Please send your comments, queries and requests for additional copies to:
Anne Loach
The Editor, RPA Newsletter
Health and Safety Executive
Level 3, North Wing
Rose Court
2 Southwark Bridge
London SE1 9HS

In Issue 6 we published an article about the combined role of RPA/RPS in schools. We want to make clear that the not all educational establishments have to appoint an RPA.

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Your views

One reader wrote to The Radiation Protection Adviser about certifying safety competence - we would welcome views of other readers on the topic: Following recent publicity over the death of an industrial radiographer, the UK approach to assuring the competence of personnel using ionising radiations in industrial radiography (and in other fields) must be questioned. In many European countries, an independent assessment and certification of competence is carried out by authorised agencies, often enforced through legislation".

HSE avoids a prescriptive approach to this problem, favouring a policy of promoting awareness through training. In this readers view "it is not sufficient just to encourage training; it needs to be mandatory, backed up by formal examination and certification". He suggests that;

"HSE and NRPB should agree and define a training syllabus, a minimum acceptable period of training (by assessed and approved organisations), and a minimum period of working under certificated supervision prior to attempting one of three levels of radiation safety examination (by accredited certification bodies) appropriate to:

  1. classified workers,
  2. radiation protection supervisors, and
  3. radiation protection advisers".

He argues that "any individual working with ionising radiations in any sector of industry or medicine" should be covered.

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The role of local rules

An operator was preparing to transfer a 100 Curie Iridium 192 radiography source from one transport container to another but was unable to complete the task. (The actual transfer would have taken place remotely inside a fully shielded facility, after manually lifting the source holder part way out of the container). He handed the job over to a second operator, who mistakenly understood that he had to load a new source from store into one of the containers. As a result of this misunderstanding, the second operator withdrew the source from the container outside the facility, thinking it was inactive. The area gamma alarms sounded and building evacuation procedures came into effect. These procedures operated successfully and the second operator was only exposed to the source for about 2 seconds receiving a dose of about 1 mSv.

The company were subsequently charged with offences of both Regulation 6 (1) and regulation 11 (1) of the Ionising Radiations Regulations 1985 (IRR85) by HSE's Nuclear Installations Inspectorate. The company accepted they did not have written procedures to cover handover of uncompleted tasks or the relatively straightforward transfer of the high activity source. However, they argued that local rules need not include detailed instructions and dose reduction trends to their staff showed they were taking all reasonably practicable precautions to restrict doses.

The Magistrate Court's attention was drawn, in particular, to the wording of the Approved Code of Practice. The court found that since the company did not have written rules governing the steps to be taken when a task is interrupted mid process, and the transfer of sources from one container to another, it had failed to comply with Regulation 11. Also, the Court found that as there were no such rules a ll necessary and reasonably practicable steps to protect the employee had not been taken: thus the company had not complied with regulation 6. This incident raises a number of points and we would like to hear your views on the following:

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Outside Workers Regulations

We gather there is still some confusion about how frequently information in the radiation passbook has to be updated where the outside worker (OW) works long term on one operator's site only. Paragraph 37 of the Approved Code of Practice (Protection of Outside Workers against Ionising Radiations) suggests that the outside undertaking (OU) should make sure that the passbook details, including cumulative dose assessment, are up to date whenever new activities are to be undertaken. Our intention was that the passbook of an OW would not need to be updated until she or he had completed the work activity and was ready to work on another site; after all the operator would be estimating their dose throughout the work. The OU would have to tell the operator about any adverse findings from a medical review, of course. Therefore, it would seem there is little to be gained in applying for an exemption in such situations; all the usual IRR85 dosimetry provisions will still apply.

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Feedback from Inspectors

After a university student had carried out work with a 2.2 mBq Ra -226 calibration source, it went missing. The laboratory was searched but the source was not recovered: it may have been disposed of with routine laboratory waste or taken away by the student. The local rules in force made no reference to the procedures for calibration sources and the accounting procedures were poor: the university was successfully prosecuted under regulations 11 and 19 of the Ionising Radiations Regulations 1985 (IRR85).

This incident shows the importance of including in local rules:

An industrial radiographer was able to enter a radiography enclosure whilst x-radiography was in progress because the hired 300 Kv x-ray set in use had not been incorporated into the enclosure's safety systems. The radiographer was an outside contractor who had not worked there before. Further controls could easily have been provided (ACOP Part 2, section 7) together with adequate instruction and supervision. HSE's investigation further revealed that the safety systems provided for the other x-ray sets in the enclosure could be easily defeated.

The facility comprised two radiography bays. The safety systems of each bay were controlled from an external wall-mounted cabinet . Warning lights indicated which x-ray set and bay was in operation. Selection was via two key operated position switches. Both keys were of the same designation making it easy to defeat the interlock. Also, it was possible to operate the x-ray set in one bay provided the safety system for the other bay was activated. The complexity of the safety systems had not been fully appreciated nor had they been subject to an adequate 'critical examination' after installation.

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Protecting members of the public

Surveys of the structural integrity of bridges may involve non-destructive testing using ionising radiation. They are often done at night when the bridge may be closed, but this is not always possible.

IRR 85 require that a controlled area be set up during such work. Only classified people, or those entering under a written system of work, may enter a controlled area; members of the public must normally be excluded. This poses a problem when it is desirable to keep the bridge open during the survey. In practice, one carriageway of the bridge may have to be surveyed while the other one is open to traffic

HSE inspectors have been involved with a bridge survey using a mobile linear accelerator mounted on a lorry. The accelerator head was positioned by gantries. Radiation was emitted onto the outer box section of the bridge column under inspecti on and was detected by a real time imaging system located inside the box section (radioscopy). This had the advantage of immediate interpretation of the bridge structure integrity.

Radioscopy requires very high dose rates for successful imaging. Preliminary surveys showed surprisingly high dose rates over the road surface of both carriageways near the linear accelerator. However, it was found that by careful positioning of the accelerator head and imaging system the controlled area could be limited to one carriageway. This meant that the survey could be undertaken whilst the other carriageway was kept open to traffic.

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Depleted Uranium Containers

HM Industrial Pollution Inspectorate (HMIPI) has recently reviewed the application of the 1993 Radioactive Substances Act to radioactive source containers used in radiotherapy and NDT work. Many of the containers incorporate depleted uranium as the shielding material which is itself a radioactive material; in some cases the quantities being held in the form of source containers are sufficient to require registration. Whilst this exercise relates to Scotland only, it is a timely reminder that use of all radioactive substances should be reviewed on a regular basis.

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Patients leaving hospital after receiving radioactive substances

Chapter 12 of the Guidance Notes for the Protection of Persons against Ionising Radiations arising from Medical and Dental Use gives advice on the conditions under which patients may be allowed to leave hospital. There have been suggestions that some of the figures in Chapter 12 are unnecessarily restrictive.

HSE has begun discussions with the British Institute of Radiology on this topic. We are eager to build up a full picture of any problems that this guidance may be causing in nuclear medicine and radiotherapy departments. We are encouraging research on the impact of the guidance and would welcome views from RPA's on the subject.

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HSE Seminars

Previous issues of The Radiation Protection Adviser highlighted HSE's concern about the adverse trend in radiation doses for industrial radiographers reported to HSE's Central Index of Dose Information (CIDI). Workers particularly at risk are those who work under 'site' conditions, i.e. in controlled areas designated only by temporary barriers (rather than in shielded enclosures).

HSE has adopted a number of measures designed to reverse this trend. At seminars for 'site radiography' companies, HSE inspectors have described the practical measures they expect companies and their clients to adopt for the management of the work in order to keep doses as low as is reasonably practicable.

An article giving further details has been prepared for INSIGHT, the Journal of the British Institute of Non-Destructive Testing.

Inspectors have stressed two key messages:

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The 'Shipments' Regulations

An article appeared in Issue 4 of the Radiation Protection Adviser about this Council Regulation. Now that Austria, Finland and Sweden have joined the EU, the relevant competent authorities are:

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STOP PRESS

Updated 2011-09-15