The Radiation Protection Adviser will be an occasional newsletter which aims to provide its readers with current, relevant information on issues of concern to RPAs. Some articles, like this issue's discussion on critical examination of the installation of dental radiography equipment, though specific, will it is hoped promote a wider understanding of HSE's views on the role of RPAs. Other articles will inform the reader of the availability of additional guidance in the field, as for example the article on guidance for Gamma Irradiators. Finally, we have taken this opportunity to bring to your attention corrections to Schedule 2 Column 4 of IRR 85 in respect of values for tritiated compounds and Polonium-210.
References to "IRR 85" or ACOP Parts 1, 2, 3. and 4 are references to the Ionising Radiations Regulations 1985, Approved Code of Practice The protection of persons against ionising radiation arising from any work activity (Part 1 and 2), Exposure to radon (Part 3) and Dose limitation - restriction of exposure; additional guidance on Regulation 6 of the Ionising Radiations Regulations 1985 (Part 4) respectively.
As this is the first issue of The Radiation Protection Adviser we would particularly welcome readers' views on the newsletter, the material in it, suggestions for future articles and, if appropriate, correspondence.
Queries and comments should be addressed to the Editor :
Health and Safety Executive,
2 Southwark Bridge,
London, SE1 9EH
Raised by NRPB, Leeds
Under Reg 32 (2)(a) of the IRR85 the installer is required to undertake a critical examination of the installation (after completion of the work) using the services of their or the purchaser's Radiation Protection Adviser (RPA). As dentists rarely have an RPA, the installer should satisfy the requirement.
HSE is satisfied that an equipment engineer with sufficient experience of dental X-ray equipment and appropriate special training is capable of being appointed as an RPA for the purpose of the critical examination. Paragraph 71 of ACOP Part 1 gives details of the experience etc required by an RPA.
All such appointments must confine the scope to the performance of the critical examination (every RPA appointment must specify the scope of the appointment). It is not uncommon for a company to appoint more than one RPA to give them expert advice on different aspects of radiation work, for example, fault finding on X-ray equipment where the equipment has to be energised for the purpose, when a different RPA may be needed to give expert advice about the precautions required and the preparation of 'local rules'.
Where a dental trade engineer has been appointed as an RPA for critical examination he should be capable of giving adequate advice to the employer about the proper conduct of those examinations. There should be no need to appoint another RPA to give that engineer additional advice on this narrow topic. Indeed, if there was such a need, the engineer would not be regarded as suitable for appointment as an RPA.
The additional guidance on Regulation 6 of IRR85, Approved Code of Practice Part 4 (ACOP Pt 4) Dose limitation - restriction of exposure, has been approved by the Health and Safety Commission. It was published in April 1991 and came into force on 1 July 1991. ACOP Pt 4 applies to all work activities covered by IRR 85 and. should be read in conjunction with ACOP Parts 1 and 2. It gives additional guidance on appropriate actions to keep doses as low as reasonably practicable (ALARP) and to control doses received by individual workers. It is an interim measure in the light of recent revisions of risk estimates and interim guidance from the National Radiological Protection Board, pending major revision of international and national legislation, which effectively restores the protection provided by IRR 85 to the level that was intended when the regulations were made.
ACOP Pt 4 identifies the need to take account of the recent revisions of risk estimates when considering whether exposure is ALARP and introduces a new investigation when an individual worker's annual exposure exceeds an average of 15 mSv within five years. Employers should therefore make arrangements with their approved dosimetry service to be informed whenever one of their employees reaches a recorded cumulative total of 75 mSv or more within any five consecutive calendar years after 1 January 1988.
Reaching such a cumulative dose should trigger an additional investigation but would not in any way imply breach of a statutory dose limit. The investigation is designed to focus on the individual, considering the recent past and looking into the future to decide what action may be necessary in the light of the risk to the individual's health from his or her actual and projected exposure to radiation.
HSE has issued two revised type approval certificates, TA1 and TA2 of 1990, for smoke detectors and luminous signs which contain radioactive sources. The purpose of the certificates is to relieve employers of the obligation to notify HSE under IRR 85 where these devices are installed and no other work with ionising radiations is carried out. The certificates apply to ionisation chamber smoke detectors and gaseous tritium light devices (including fire exit signs) which satisfy conditions set out in the certificates.
The principal changes concern ionisation chamber smoke detectors. The replacement certificate of approval for these detectors is restricted to devices which are of a type that has been shown to conform to Recommendation for Ionisation Chamber Smoke Detectors - Implementation of Radiation Protection Standards, published by OECD-NEA 1977, available from The Stationery office.
Employers should check that their devices conform to the conditions in the revised certificates and should notify the local office of HSE if the devices cannot be shown to satisfy these conditions.
There is no suggestion that devices need to be replaced it they no longer conform to the type approval conditions. It is simply that notification to HSE becomes necessary.
Certificate of Approval TA1 of 1989 is not affected by the revisions being introduced. This covers storage of ionisation chamber smoke detectors containing not more than 40 kBq americium-241 in any detector and only applies when the number of such detectors present in any building or premises is less than 500 and where work with ionising radiations arises solely from the storage, handling or disposal of such detectors, provided that in no case shall any detector be dismantled.
The revised certificates took effect from 1 January 1991. Copies of the certificates, TA1 and TA2 of 1990, can be obtained from HSE Nuclear Policy Branch, Radiation Protection Policy Section, NII A4, Room. 216, Baynards House, 1 Chepstow Place, London W2 4TF, telephone 071-243 6836.
Raised by NRPB, Leeds
Written Systems of Work (WSW) are gaining favour because, as intended, they can be administratively more simple and can avoid over-classification. It is important, however, to ensure that no loss of control results, ie:
The quantity given in Schedule 2, Column 4 of IRR 85 in respect of surface contamination by Tritium (H-3) and tritiated compounds has been reassessed and found to be incorrect. The correct activity concentration should be 4x105 Bq cm-2. There has been a transcription error in Schedule 2, Column 4, relating to Polonium-210. The correct figure should be 10 Bq cm-2.
The current system for the approval of dosimetry services under Regulation 15 of IRR 85 has been in operation for nearly five years. Therefore, HSE decided to review the arrangements for approval to find out whether any improvements or alterations could be made.
The review revealed several areas where changes were necessary which would, HSE believes, benefit employers, Approved Dosimetry Services (ADSs) and HSE. Having consulted interested parties HSE has developed specific proposals to amend the current arrangements and have revised the existing publications: Guidance on Approval of Dosimetry Services under the Ionising Radiations Regulations 1985 to reflect these proposals. The new publication will be Requirements for the Approval of Dosimetry Services under the Ionising Radiations Regulations 1985 (RADS) and should be available later this year.
The new document clarifies HSE's minimum requirements for approval by setting out the objectives, the procedure to be followed to apply for approval and the specific criteria to be met by ADSs. Additionally, the requirements for internal dosimetry and accident dosimetry will be explained in some detail (which could not be done initially when the existing documents were produced). One of the most important proposals concerns the time limitation on approvals; currently, certificates of approval are issued for fixed periods only. HSE now believes that it would be sensible to grant approvals without a time limit; this would give a more flexible arrangement than at present and would avoid the risk of a satisfactory ADS temporarily losing formal approval because of delays in the re-approval process.
However, approval will be reassessed at the same frequency and at about the same time as reapplication for approval would have occurred for any particular service under the present arrangements. Also the ADS will be required, where appropriate, to arrange a performance test for the service with a suitable test house.
Naturally HSE must retain a formal mechanism for removing approval from an unsatisfactory dosimetry service. Therefore, for the first time, HSE has set out its policy on the revocation of approvals as provided by Regulation 15 of IRR 85. Circumstances have been identified in which this step would be considered and an explanation given of the formal process by which revocation would be implemented.
Guidance has been published entitled Radiation Safety for Operators of Gamma Irradiation Plants. These notes were prepared by the UK Panel for Gamma and Electron Irradiation, with advice from HSE, to assist operators of Gamma irradiation plants to comply with the requirements of IRR 85, and other relevant legislation. The process is currently used for the sterilisation of medical devices and the treatment of plastics, materials etc.
The notes are not intended to cover all parts of the regulations in detail, but provide assistance on points specific to users of large irradiation sources. Copies of the guide are available free from Mr B C Ross, Technology Division, Magdalen House, Stanley Precinct, Bootle, Merseyside L20 3QY.