1

REQUIREMENTS FOR THE APPROVAL OF

DOSIMETRY SERVICES UNDER THE IONISING

RADIATIONS REGULATIONS 2017

(Updated 2020)

PART 2 - INTERNAL RADIATIONS

2

2

These requirements, which include technical criteria for approval and supporting

guidance, are issued by the Health and Safety Executive for the purpose of ap-

proving dosimetry services under regulation 36 Ionising Radiations Regula-

tions 2017. Following the supporting guidance is not compulsory and dosimetry

services are free to take other action to demonstrate that the criteria in this docu-

ment have been met.

3

FOREWORD Dosimetry services undertaking assessment and record-keeping of radiation doses received by classified persons must be approved for these purposes by the Health and Safety Executive (HSE) or by a body authorised in writing by HSE. The organi-sation responsible for approving dosimetry services is referred to in this document as the 'Approval Body'. The requirements which must be satisfied to obtain approval are specified in three parts. This part sets out the procedures and criteria that will be used by the Approval Body for the assessment of dosimetry services seeking approval for the measure-ment and assessment of doses arising from internal radiations (including radon de-cay products). Part 11 deals with approval for external radiations (including expo-sures resulting from accidents) and Part 32 deals with co-ordination of dose assess-ments and record keeping of reported doses. These documents set out the objectives to be achieved and the requirements a ser-vice must satisfy to meet those objectives. This document is in three sections. The first section gives an introduction; the second section describes procedural require-ments; and the third section gives criteria for approval. The criteria for approval are supplemented by guidance to indicate how they may be satisfied. This guidance is intended to help dosimetry services and the Approval Body. It shows ways in which services have met the criteria in the past, and illus-trates good practice. Following the guidance is not compulsory and dosimetry ser-vices are free to take other action to demonstrate that they meet the criteria in this document. Separate guidance3 is available for employers summarising their respon-sibilities. Printed and published by the Health and Safety Executive

RADS 2/2019

4

CONTENTS Page Number FOREWORD SECTION ONE Introduction Background .......... 1 Accident dosimetry .......... 2 Objectives .......... 2 SECTION TWO Procedural requirements for approval/revocation Applications for approval .......... 3 Reassessment of approved dosimetry services .......... 3 Assessment for approval/continuing approval .......... 4 Fees for approval/continuing approval .......... 5 Performance tests .......... 5 Conditions of approval .......... 7 Revocation of an approval .......... 10 Figure 1 .... Flowchart showing steps in applications for approval .......... 14 Figure 2 .... Flowchart showing steps in reassessment of an approval ........ 15 SECTION THREE Criteria for approval General .......... 16 Quality assurance .......... 17 Methods of dosimetry .......... 18 Assessment of intakes .......... 19 Calibration of the dosimetry system .......... 21 Reliability of service .......... 21 Dose assessment .......... 22 Reassessment of doses .......... 23 Advice to clients .......... 23 Reporting results to other ADS .......... 24 Reporting dose assessments in the event of an accident .......... 27 Late return of samples/dosemeters and receipt of contaminated samples ... 28 Periodic performance tests .......... 28 Annex to HSE criteria for approval .......... 30 References .......... 32

5

Appendices 1. Statement of Service .......... 34 2. Notional and Estimated Doses .......... 39

6

SECTION ONE

Introduction

Background 1. Regulation 36 of the Ionising Radiations Regulations 20174 (IRR17) enables the Health and Safety Executive (HSE) to approve suitable dosimetry services for some or all of the purposes of: (a) Regulation 22 (routine dose assessment and record-keeping for classified persons); and/or (b) Regulation 24 (dosimetry for accidents); and/or (c) Regulation 13 (provision of dosemeters or other devices for accidents), and to revoke such approvals in writing at any time. HSE may at any time make an agreement in writing with another body to perform this approval function instead. In this document, the term 'Approval Body' is used to mean either HSE or a body ap-pointed by HSE to undertake the approval function in place of HSE. 2. Dosimetry Services may be approved to: (a) assess doses received by classified persons, including the measurement and assessment of whole-body or part-body doses arising from inhaled, ingested or ab-sorbed radionuclides and the provision of relevant information to a service approved for record-keeping; or (b) undertake part of the dose assessment procedure, such as the measurement of tritium concentrations in urine; or (c) assess doses following an accident, occurrence or incident and to report the results to the employer and to the dosimetry service approved for record-keeping when appropriate. In this document, dosimetry services approved for any of these purposes are re-ferred to as ADS (Assessment); dosimetry services approved for co-ordinating con-tributions to dose assessments and for dose record-keeping are referred to as ADS (Records). 3. HSE has issued a series of publications setting out requirements for the ap-proval of dosimetry services under IRR17. This part deals with those aspects which are relevant to the assessment of doses from internal radiations. It explains: (a) the criteria the Approval Body will use to assess whether a dosimetry service appears fit for approval or for continuing approval; (b) the arrangements for performance testing (where relevant);

7

(c) the information to be sent to ADS (Records); (d) the circumstances in which an approval may be revoked. Accident dosimetry 4. Any service approved for routine measurement and assessment of doses from internal radiation is expected to be capable of assessing and reporting doses rapidly following acute intakes as a result of an accident, occurrence or incident, when requested to do so by the employer; see also criterion 5. Consequently, the approval of a dosimetry service for routine assessment of doses from internal radia-tions will include accident dosimetry relating to acute intakes of radionuclides. Objectives 5. Any dosimetry service seeking approval to assess doses from internal radia-tions must demonstrate to the Approval Body that it has the necessary expertise in the type of dosimetry for which it seeks approval and can provide and maintain a service which: (a) produces a reasonable degree of accuracy in the assessment of dose (or con-tribution to such assessment); (b) is highly reliable; (c) communicates the results of routine dose assessments to a dosimetry service approved for co-ordination and record-keeping (or forwards the results of other work for which it is approved) in reasonable time; and (d) rapidly communicates to the employer, and subsequently to ADS (Records), the results of dose assessments made in the event of an accident, occurrence or in-cident. 6. This document sets out the criteria developed by HSE, after consultation with approved dosimetry services (ADS), which will be used to decide whether or not a dosimetry service can meet the objectives in paragraph 5. Any service that can sat-isfy the Approval Body that it meets the relevant requirements will receive formal ap-proval under Regulation 36 of IRR17, subject to certain conditions governing the scope of that approval and the maintenance of the standard of service.

8

SECTION TWO

Procedural requirements for approval and arrangements for revo-cation of approvals

Applications for approval 7. HSE publishes a Statement on the Approval of Dosimetry Services (HSE Statement) which sets out: (a) the arrangements for making applications for approval and for reassessing approved services; (b) the requirements for performance testing of dosimetry services; and (c) the current fees charged by the Approval Body. The HSE Statement is revised from time to time and will include any changes to the requirements for approval including new or revised performance tests. Copies of the HSE Statement can be downloaded here- http://www.hse.gov.uk/radiation/ionising/dosimetry/ads.htm 8. Applications for approval should be made in writing or via email to the Ap-proval Body specified in the current HSE Statement and must include: (a) a description of the type and size of service for which approval is sought, and for example, "assessment of intakes and committed dose (using bio-assay, in-vivo counting and air sampling) principally for the following radionuclides or class(es) of radionuclides ..."; (b) the full name and address of the dosimetry service; (c) (if the service is to be limited to certain clients or groups of clients) the names of clients or a description of groups of client; (d) a Statement of Service which gives the required details about the service (see paragraph 10); (e) a copy of a signed certificate for a successful performance test, where rele-vant (see paragraph 17); and (f) the appropriate administration fee (see current HSE Statement). Reassessment of approved dosimetry services 9. Approvals are normally granted without a time limit but each approved dosim-etry service (ADS) will be subject to formal reassessment if, in the opinion of the Ap-proval Body, the performance of the ADS has fallen or is suspected of falling below

9

the standards required and/or is not in accordance with their Statement of Service. A fee for this reassessment will be charged Assessment for approval/continuing approval 10. The dosimetry service must ensure that the Statement of Service is accurate, up-to-date and sufficient to support the application for approval /continuing approval when considered with any referenced publications and supporting documents. It must cover all the relevant points in Appendix 1, providing a summary of how the cri-teria in section 3 of this document are to be satisfied. The Statement of Service should identify how each element of Appendix 1 is addressed, for example by using the same layout or by including an executive summary which explains how each item is covered (e.g. with cross-references to particular paragraphs in the Statement of Service). If it is not clear whether the Statement of Service covers all the points re-quired it will take longer to deal with the application. Inevitably, this will increase the fee for assessing the application (see paragraph 16). 11. If the assessor decides that the Statement of Service is incomplete or inade-quate for the purposes of assessment, he or she will ask the dosimetry service to amend it. The assessor may also request copies of any relevant supporting docu-ments referenced in the Statement. If the dosimetry service does not then provide an adequate Statement of Service for assessment (and copies of requested support-ing documents) and appears to be incapable of demonstrating that it can satisfy the criteria in this document, the Approval Body will reject the application for approv-al/continuing approval. 12. The assessor will arrange an inspection of the applicant’s facilities at a mutu-ally convenient time. Normally, this inspection will take place after the assessor has received satisfactory replies to queries about the Statement of Service submitted with the application. The assessor will then sample inspect key features of the facili-ties and the arrangements for dosimetry to check that these match the description in the Statement of Service and are sufficient to indicate that the service is fit to be ap-proved. (Figure 1 illustrates the process of dealing with applications for approval and figure 2 relates to reassessments of approvals). Dosimetry services wishing to be approved are responsible for ensuring that they comply fully with the relevant criteria for approval and should not rely on the assessor to identify any gaps in their ar-rangements. 13. An assessor carrying out a reassessment of an ADS will take into account the overall performance of the service since the last assessment (including the results of performance tests). The results of any review of performance required under criteri-on 20 must be made available to the assessor at the inspection. The Approval Body may consider that the criteria for reassessment are not satisfied if the ADS has failed to carry out a required review or has failed to act on the results of such a review. 14. If the assessment of doses depends on two or more parts of the organisation (e.g. one site carries out analysis of urine samples but another site makes the dose assessment) both may need approval either separately or jointly for the particular work they carry out.

10

Guidance

on

paragraph 14

Dosimetry services operating from more than one site In some cases, certain operations connected with the work of the service are carried out on another site. In such cases it may be nec-essary for both sites to be named in the approval or even for two separate approvals to be granted. A second site may need to be mentioned in the certificate of approval for a service where the amount or type of work done forms a signifi-cant part of that dosimetry service's work. The key test for separate approval is control: if the applicant for ap-proval exercises control over the work at the second site separate approval will not be required. However, if the work at the second site is not under the effective control of the first dosimetry service a sepa-rate approval or evidence of accreditation by the United Kingdom Ac-creditation Service for that specific work may be required.

15. The Approval Body will aim to carry out an inspection of the applicant's facili-ties within two months of receiving a formal application and to reach a decision about approval within four months of that inspection. The inspection will be delayed if the Statement of Service is not adequate for the purposes of assessment (see par-agraph 11). The Approval Body will explain in writing the reasons for rejecting any application. If the applicant is aggrieved by the decision it may use the Approval Body's disputes procedure. However, the decision of the Approval Body after use of this procedure will be final. If an application is unsuccessful the service may make a fresh application for approval but a further fee will be payable. Fees for approval/continuing approval 16. A fee is payable for all applications, whether or not they are successful. The fees are set out in the current HSE Statement. An applicant for assessment/ reas-sessment will have to pay, in advance, a basic administration fee for any application to cover handling costs. There will also be an assessment fee to cover both the cost of any work undertaken by the Approval Body in connection with the application and the reasonable travel and subsistence costs of the Approval Body's assessor who visits the facilities of the service (details are given in the current HSE Statement). The applicant will be asked to pay this additional fee after the visit. The Approval Body will not make a final decision about approval until this fee has been paid. Performance tests General 17. For certain methods of dose assessment dosimetry services are required to undertake a performance test both prior to approval and at intervals not exceeding 18 months thereafter. The current HSE Statement explains which types of dosimetry service will have to undertake performance tests and sets out the pass/fail criteria that will be applied. Each type of test is described in a protocol issued by HSE. The test results will be assigned to one of three Bands: A, B or C, as described in the HSE Statement.

11

18. The dosimetry service must arrange the performance test with a laboratory service which has received accreditation from the UK Accreditation Service (UKAS) to carry out the particular test in accordance with the relevant published HSE proto-col (available on request from the Dosimetry Services Administrator, HSE Radiation Team, Redgrave Court, Merton Road, Bootle, Merseyside L20 7HS. Tel: 020 3028 3051 . Email rad-admin@hse.gov.uk). The applicant is responsible for paying the laboratory to carry out the test. A list of these laboratories can be obtained from UKAS whose contact details are here http://www.ukas.com 19. If no laboratory has received UKAS accreditation for the type of test required, the dosimetry service must arrange for the test to be carried out by either the Na-tional Physical Laboratory (NPL) or Public Health England (PHE), except that PHE must arrange for tests of its own services to be carried out by NPL in these circum-stances. 20. If a dosimetry service seeks approval for a method of measurement for which it already has UKAS accreditation it need not undertake a performance test. It will, however, have to show the Approval Body that its accreditation by UKAS remains current.

Guidance

on

paragraph 20

It is not sufficient that the organisation of which the dosimetry service is a part has UKAS accreditation; the service itself must have the rel-

evant accreditation.

Performance test required before approval 21. Applicants for approval should undertake a performance test, where required, no more than three months before application for approval is made. To pass a per-formance test, applicants for approval must obtain test results which lie in 'Band A'. The applicant must supply the Approval Body with a copy of a signed certificate from the test laboratory, setting out the results of the test. If the applicant fails the pre-approval performance test (i.e. the results of the test are not within 'Band A') it may undertake a further performance test, after correcting any errors in the methods used. Periodic performance tests 22. Services required to undertake periodic performance tests must obtain test results that fall either in ' Band A' or in 'Band B'. If the ADS undertakes a perfor-mance test and obtains a 'Band B' result it must carry out an in-service review to ex-amine ways of improving the service. The Approval Body will consider the outcome of such reviews at the time of any reassessment (see paragraph 13). If the test is unsuccessful ('Band C') the ADS may arrange a further test (but see criterion 20 and paragraph 23).

12

23. The ADS must send the Approval Body a copy of a signed certificate from the accredited test laboratory setting out the results of the periodic performance test un-dertaken in accordance with criterion 19. This certificate must be dated within the period of 18 months since the date of the previous certificate. If the results of the performance test are unsuccessful (‘Band C’) the ADS must immediately undertake a thorough in-service review and develop an action plan for improving the service. The ADS must send a copy of the plan to the Approval Body, together with a report of the in-service review, no later than three months after the end of the 18 month pe-riod allowed for performance tests

Guidance

on

paragraph 23

An ADS that has failed a performance test and submitted its action plan to the Approval Body may choose to undertake a further test to demonstrate that the improvements it has made have been effective. In such cases, if a copy of a successful test certificate is sent to the Approval Body within the three month period referred to in paragraph 23 the next performance test will not be required until 18 months from the date on that certificate.

24. An approval may be revoked if the ADS does not provide a copy of the per-formance test results and, where necessary, a report of an in-service review and ac-tion plan, within the period allowed. Conditions of approval 25. Where the techniques used are dependent on site-based factors (e.g. static air sampling) the approval will be site-specific. 26. Approvals granted for the assessment of doses from the prolonged retention in the body of long-lived radionuclides may contain a specific provision for the report-ing of improved dose estimates in accordance with the principles set out in the pub-lished HSE guidance on dose assessment from such radionuclides5. 27. The scope of any approval will be limited by Schedule 1 of the certificate of approval. Schedule 2 may specify conditions which, for example, restrict the ap-proval to making dose assessments for specified workplaces or for particular types and energies of radiation. An approved dosimetry service proposing to extend the scope of its approval or to use a different dosimetric technique must make a further application to the Approval Body; an additional fee will be charged.

Guidance

on

paragraph 27

Selection of ADS by the employer It is the employer's responsibility under regulation 22 IRR17 to ap-point an ADS (Assessment) that can make appropriate measure-ments, considering the work undertaken and the types and form of radionuclides to which employees are exposed. The employer would be expected to consult the Radiation Protection Adviser (RPA) and the ADS (Records) and to take account of any conditions of approval placed on the ADS (Assessment). Therefore, an ADS (Assessment) should take care to inform potential clients about the scope and con-ditions of its approval - normally a copy of the certificate of approval could be made available to clients or their RPA(s). See also criterion 13.

13

Different dosimetric technique

One example of a different dosimetric technique would be where an ADS approved to make measurements using an air sampling method wished to supplement this with in-vivo monitoring or with a bio-assay technique.

28. Schedule 2 of the certificate restricts the manner in which measurements and assessments are undertaken to those summarised in the relevant Statement of Ser-vice agreed at the time of approval. Any significant change to the dosimetry system (including the main laboratory techniques, design of instrumentation and methods of assessment used) or to key personnel (e.g. the head or the deputy head of the ser-vice) requiring a revision of the Statement of Service might invalidate the approval; changes restricted to supporting documents would not affect the certificate of ap-proval. Therefore, an ADS should inform the Approval Body, in advance where prac-ticable, of significant changes to the following: (a) key staff (b) location of the service (c) dosemeter (e.g. for radon) or a device e.g. personal air sampler (d) radioanalysis equipment and technique (e) calibration system. (f) methods of dose assessment where the change would require a significant revision to a critical part of the State-ment of Service referred to in the certificate of approval. If the Approval Body de-cides that the changes could adversely affect the competence and performance of the ADS to maintain the service in accordance with the requirements in this docu-ment a partial reassessment may be needed. The Approval Body will arrange for one of its assessors to review the changes and to undertake a partial reassessment of those aspects of the service which have changed; this may involve an inspection. A fee will be charged for such a reassessment whether or not an inspection is in-volved.

14

Guidance

on

paragraph 28

Purpose of notification to the Approval Body This should not be seen as a discouragement to innovation. Its pur-pose is to: (a) help the Approval Body ensure that modifications to the op-

eration of an approved service do not result in the service failing to conform to the criteria for approval; and

(b) help ensure that the operation of the service is still covered

by the existing certificate of approval (which will refer to a statement of service current at the time of approval or at the time of the last reassessment).

If an ADS provides a service that is not covered by the current ap-proval certificate (e.g. measurements of radionuclides other than those principal radionuclides or classes of radionuclides specified in the approval certificate) then it may be acting as an unapproved ser-vice. Its clients would therefore be in contravention of regulation 22 IRR17. Similarly, any relocation of the service to different premises could invalidate an existing Certificate of Approval. Similarly, any re-location of the service to different premises could invalidate an exist-ing certificate of approval. In most cases, the Approval Body can agree a variation by confirming its acceptance of the change in a let-ter to the ADS. Changes to supporting documents which do not re-quire a modification to the Statement of Service need not be notified to the approval body.

29. Approvals are given to a specific dosimetry service and cannot be transferred in part or whole to any other dosimetry service. Therefore, it is imperative that an ADS notifies the Approval Body if a change of name is planned as the existing certif-icate of approval might not be valid for the new organisation. 30. At the request of HSE, an assessor may arrange for: (a) a visit to the ADS, at a reasonable time, to make enquiries about any signifi-cant problem that has come to HSE's attention and to carry out an interim assess-ment of the service if appropriate; and/or (b) a performance test to be carried out by one of the laboratories accredited by UKAS for the relevant test, or where that is not possible, as indicated in paragraph 19. 31. The ADS should co-operate with the assessor in these circumstances. No fee will be charged - HSE will normally pay for this work. However, the approval of a service may be revoked in any of the circumstances set out in paragraph 32. Revocation of an approval 32. HSE may revoke in writing any approval given to a dosimetry service. An ap-proval for internal radiations may be revoked if an ADS:

15

(a) does not send performance test results in 'Band A' or 'Band B' to the Approval Body (where such tests are required) within the period set out in criterion 19 and paragraph 21, or fails a performance test carried out under paragraph 30(b) (though account will be taken of in-service reviews and action plans referred to in para-graph 23); (b) does not conform to the current criteria for approval and fails to provide the Approval Body with an action plan which is sufficient to enable the deficiencies to be rectified within three months; (c) persistently fails to report dose assessments or complete the work for which it is approved within the required period specified in criterion 14; (d) fails to provide a copy of the current Statement of Service within three months of receipt of a written request from the Approval Body (see paragraph 9), or such longer period as may be agreed; (e) fails to provide the required fees for reassessment (see paragraph 16) within three months of receipt of a written request from the Approval Body, or such longer period as may be agreed; (f) fails to co-operate with the Approval Body during attempts to carry out an in-terim reassessment or performance test (paragraph 30); An approval will also be revoked if a dosimetry service requests revocation of its ap-proval or is issued with a new certificate that supersedes the previous certificate.

16

Guidance

on

paragraph 32

Monitoring performance The ADS should be monitoring its own performance against the tar-gets set out in this document (see criterion 3). Therefore, it should be aware of any failure to provide performance test results to the Ap-proval Body on time, to supply a copy of the Statement of Service to enable a reassessment to proceed or to pay the required fees for re-assessment. Similarly, the service should be aware of the time it takes to provide the results of assessments to ADS (Records), or to complete the work for which it is approved (if this constitutes only part of the assessment process).

Failure to notify significant changes

If an ADS fails to notify the Approval Body of significant changes like-ly to affect the Statement of Service (paragraph 25) this would not, in itself, justify revocation of its approval. However, if the Approval Body discovers that significant changes have been made which have ad-versely affected the performance of the service it may consider revo-cation of the approval, as explained in paragraph 31 below.

Period for completion of assessment work

For long-lived, long-retained radionuclides see guidance to criteria 14 and 15. Where two or more services work together to provide an assessment of dose (e.g. one service measures the concentration of a radionu-clides in urine and another assesses the dose and reports the result to ADS (Records)) they should aim to ensure that the service report-ing the dose can do this within 14 days of the first service receiving the bio-assay samples etc (but see guidance to criteria 14 and 15). The Approval Body will normally regard the failure to complete as-sessment work within this period as 'persistent' if more than 25% of the results over a representative period take longer than 14 days (but see guidance to criteria 14 and 15).

Action Plans

If the Approval Body discovers that the ADS is not conforming to the criteria in this document the ADS will be reassessed and asked to prepare an urgent action plan. The plan should normally show what steps the service will take, with milestones, to restore the level of its performance to that required for a service approved to assess doses from internal radiation. If the ADS does not produce an action plan within a reasonable period set by the Approval Body, or the plan is unrealistic or inadequate, the Approval Body may consider revocation of the service's approval.

33. In the circumstances described in paragraph 32, the Approval Body may con-clude that revocation of the approval should be considered. In such cases, the Ap-proval Body will warn the ADS in writing, outlining the key requirements which are not being satisfied. The ADS will be asked to take action to meet these requirements within three months. If the ADS satisfies the Approval Body that it does conform to

17

the requirements in this document, or that it would be unreasonable to require more to be done, no further steps will be taken to revoke the approval. In any other case, the assessor will recommend revocation of the approval. The Approval Body will immediately notify the ADS in writing seeking comments. Subsequently, the Ap-proval Body will consider the recommendation of the assessor together with any writ-ten representations from the ADS and decide whether the approval should be re-voked. The ADS will be notified of the decision immediately. If the decision is to re-voke the approval this will take effect six weeks after the ADS is notified. This period should be sufficient to enable the clients of the service to make alternative arrange-ments.

Guidance

on

paragraph 33

Responsibility for identifying improvements Although the Approval Body will identify the main failings of the ser-vice whenever it considers revocation, it remains the responsibility of the ADS, not the Approval Body, to determine what steps need to be taken to improve its performance.

Action after receipt of a warning letter

If an ADS receives a letter warning that revocation of its approval is being considered the ADS would be unwise to take on any new cus-tomers until the problems identified by the Approval Body have been resolved. Furthermore, it may be necessary for the ADS to prepare existing customers for the possibility that arrangements may have to be made with an alternative ADS.

Disputes procedure

HSE has a disputes procedure whereby anyone who is aggrieved by the actions or decisions of HSE staff may make representations to have the matter resolved at a higher level within HSE. If a dosimetry service is aggrieved during the assessment of the service, and wish-es to pursue the matter, it should be taken up by writing to the indi-vidual's senior officer. The name of that officer appears on all corre-spondence sent out by HSE. If the Approval Body is not HSE, that body will have a similar disputes procedure. If the Approval Body recommends that approval should be withheld or revoked, or granted subject to certain conditions, HSE will write to the dosimetry service. Two weeks will be allowed to enable the do-simetry service to make representations, which will be considered on a fair and fresh basis before a decision is taken.

Guidance

on

paragraph 33

(continued)

18

Meetings with the Approval Body In appropriate circumstances, and where time can be saved in so do-ing, a representative of the Approval Body may arrange a meeting with the ADS, at the office of the Approval Body, to explain why it is considering revocation of the approval.

19

Figure 1 - Applications for approval (Internal radiations)

Applicant Prepare Statementof Service

Queries

by

assessor

Further

details/

amended

Statement

of Service

Approval Body passes case to assessor

Assessor inspects

dosimetry service

Assessor reports

to Approval Body

Approval Body

decision on

application

Appoval Body's

disputes procedure

Application rejected

with reasons

Fee paid?

within

two

months

Obtain

'Band A'

Performance

Test

result if

relevant

within

about

four

months

Applicantinvoiced for

assessment

fee

RADS

Study

Part 2

Certificate of

Approval

sending Statement

of Service, test

certificate and

administration feeto Approval Body

Apply for approval

20

SECTION THREE

HSE Criteria for Approval General Criterion 1. The service shall be able to demonstrate that it has the neces-sary staff, expertise, resources and facilities to provide and maintain a service which: (a) produces a reasonable degree of accuracy in the assessment of dose (or contribution to such assessment); (b) is highly reliable; (c) communicates within a reasonable time (i) the results of routine dose assessments to a dosimetry service approved for co-ordination and record-keeping, or, (ii) the results of their part of the process to an ADS which is approved for the subsequent part or parts; and (a) rapidly communicates to the employer, and subsequently to ADS (Rec-ords), the results of dose assessments made in the event of an accident, oc-currence or incident. Criterion 2. The service shall take all reasonable steps to ensure that the fa-cilities and general arrangements provided for the measurement and assess-ment of individual doses and the calibre of staff engaged in this work conform to the standards set out in the HSE publication 'General guidance for laborato-ries providing personal dosimetry services6.

Guidance

on

Criterion 2

Experience and independence of staff 2.1 Current staff should have the relevant dosimetry experience and standing and adequate training programmes should be available for new staff. The head of the service should possess qualifications and experience appropriate to the type of dosimetry for which ap-proval is required . The service should be prepared to show that it is independent in character. The responsibilities of staff should be clear and appropriate, for example, if the head of a dosimetry service also fulfils another function for a client employer, such as radiation protec-tion adviser, the two roles should be clearly distinguished; and the lat-ter role should not be allowed to interfere with the former

21

Guidance

on

Criterion 2

(continued)

Standard of facilities 2.2 No dosimetry service is likely to gain approval if its facilities for carrying out the work are:

• very cramped;

• insecure (for example sensitive areas of the facility are readily accessible to staff from another part of the organisation);

• subject to significant levels of external radiation or radioactive contamination; or

• not under the direct control of that service. 2.3 In deciding whether or not a dosimetry service satisfies this criterion the Approval Body may take account of the scope of the do-simetry service concerned. However, it is for the dosimetry service to show, in particular circumstances, why it is not reasonable or neces-sary to meet the standards in the general guidance document5.

Quality assurance Criterion 3. The service shall have written quality assurance procedures for monitoring its overall performance. As part of these procedures all docu-ments relating to the operation of the service including the current Statement of Service and supporting documents shall have appropriate quality assurance control and be formally approved by the service.

Guidance

on

Criterion 3

The objective of any quality assurance (QA) programme should be to implement a systematic process which will provide confidence that the results are accurate, conform to the criteria for approval and are retrievable. QA procedures should typically cover such matters as:

• selection and training of staff

• clear description of working methods

• avoiding contamination of samples

• calibration and checking of the measurement system

• arrangements to ensure that items of ancillary equipment contin-ue to fulfil their required functions

• interface with employers

• inspections, checks and reviews to verify that the work is per-formed in an acceptable manner

• an audit of specific performance measures such as meeting the reporting requirement to ADS (Records)

• procedures for investigating abnormal dosimetric results which might indicate a possible fault with the service (e.g. an unusually high dose assessment)

• preparation of sufficient records to show traceability of results re-ported to ADS (Records).

22

Methods of dosimetry Criterion 4. The assessment of individual doses shall be based on (a) and (b) below. (a) systematic estimation of intakes of radionuclides into the body using suitable models and a suitable combination of one or more of the following:

(i) measurement of the exposure of the person to airborne radioactivity, whether by use of individually identifiable passive dosemeters, personal air samplers, or by a combination of static air samplers and occupancy; (ii) direct measurement of the presence of radioactivity in the body; (iii) measurement of the excretion of radioactivity; and

(b) evaluation by the use of suitable models of the 50 year committed doses resulting from the assessed intakes. A dosimetry service may be approved to undertake all of the above functions, or just some of the functions. Criterion 5. The service shall draw up and adopt a suitable strategy for the assessment of dose, involving one or more of the techniques referred to in cri-terion 4 which are most appropriate taking into account the nature of any radi-oactive materials that any classified persons may be exposed to and the na-ture of the working environment; this strategy shall be designed to cater both for chronic (multiple) and acute (single) intakes of radionuclides.

Guidance

on

criterion 5

Overall strategy 5.1 Dosimetry services should be prepared to explain the strate-gy to be adopted for the assessment of dose either from chronic ex-posure, or from acute intakes, or from a combination of chronic and acute intakes in the case of radionuclides with a half life (radioactive or biological) exceeding a day. In some cases a single technique will normally be sufficient, for example the assessment of committed doses from intakes of I-131 using part-body monitoring (of the thy-roid) or the assessment of committed doses from intakes of tritiated water using bio-assay. In other cases, most notably the assessment of dose from intakes of actinides, a combination of techniques will be required to give the best assessment of dose.

23

Guidance

on

criterion 5

(continued)

5.2 The general strategy for weighting and combining the meas-urements derived from various techniques may be standardised for most assessments. It may take account of specific workplace factors which can be justified, for example the use of respiratory protective equipment (the employer should provide justification for any factors applied to reduce the dose assessed using air monitoring). 5.3 It may also allow for expert judgements to be made to pro-vide best estimates in some cases, particularly where acute intakes have been received which suggest 50-year committed doses are ap-proaching a relevant dose limit. See also the guidance to criterion 11 which gives advice on the use of material and workplace specific parameters in accepted biokinetic and dosimetric models. 5.4 The dosimetry service should be prepared to demonstrate its general strategy and, in broad terms, the scope for expert judgement. Where well established methods are used which are based on pub-lished (and referenced) sources it is unlikely that justification will be required for the general methodology used, provided that the meth-ods are suitable for the particular application and specific parameters and assumptions within those methods are explained. ICRP publication 788 gives an overview of the techniques that may be considered.

Assessment of intakes Criterion 6. The service shall make systematic measurements and assess-ments of individual intakes using: (a) established techniques for given radionuclides in specified chemical and physical form and for specified route or routes of intake, or (b) techniques which can be shown to have an accuracy, reliability and suitability comparable with established techniques for the relevant working environment(s).

Guidance

on

criterion 6

Use of personal dosemeters 6.1 At present, the only type of service which makes use of per-sonal dosemeters is one that assesses doses from inhalation of ra-don gas and its decay products. While dosemeters are preferred to any other method of assessing dose, personal radon dosemeters are not necessarily suitable under all environmental conditions. Also, it is necessary to establish the average equilibrium factor(s) between ra-don and its decay products in the work areas of interest (and to es-tablish that the factor does not vary significantly over time). Dosime-try services proposing to use a method for the assessment of dose from radon (and its decay products) which does not make use of per-sonal dosemeters should be prepared to justify this approach. Ser-vices should determine the environmental conditions which would ad-versely affect the performance of the dosemeters (the scope of the service may be limited accordingly) and should justify the use of par-ticular equilibrium factors or other factors used in the calculation of

doses.

24

Long-lived radionuclides 6.2 Further guidance, including advice on the balance between personal air sampling (PAS) and static air sampling (SAS), is given in the HSE publication on long-lived radionuclides5 . The determination of a stable PAS/SAS ratio within well defined zones is of particular importance where reliance is placed on the results of static air sam-pling.

Sampling regime

6.3 Whatever measurement techniques are used, the dosimetry service should demonstrate a high degree of reliability in linking those measurements uniquely to the individual who wore the dosemeter or personal air sampler, gave the sample, or who was subjected to whole-body monitoring, as appropriate. Where the service relies on the client employer to undertake some of this work it will need to con-sider suitable auditing arrangements so as to demonstrate that it re-tains managerial control over the process.

Acute intakes of radionuclides

6.4 ADS approved for assessing dose from intakes of tritium of-ten assume that any intake occurred at the midpoint of the time since the previous sample. However, they should also make provision for assessing dose from intakes on a known date. If the employer can-not inform the ADS about the date on which an intake was received it is reasonable for the ADS to assume either that the intake was uni-form over the period or that it was received in the middle of the peri-od. However, the guidance provided to the employer by the ADS could request details of any suspected intakes so a different model can be used to assess acute exposure.

Guidance

on

criterion 6

(continued)

6.5 ADS should normally ensure that assessed doses are report-ed to ADS (Records) within 14-28 days, depending on the steps in-volved in making the assessment (see criterion 14). However, there may be circumstances where it would be unreasonable to report a dose within 28 days, for example when a PAS measurement for long-lived long-retained radionuclides indicates an intake exceeding 1 ALI. In such cases, other methods may have to be used to arrive at a best estimate of the dose received. The ADS should inform the employer and ADS (Records) immediately but not report a dose - the formal dose record would be annotated to show that an investigation was underway. The ADS assessing the dose should report 'final' dose for inclusion in the record within about 3 months (and no later than 6 months) of the intake.

Criterion 7. The service shall, where appropriate, conform to the standards set out in NAMAS information sheet on assessment of whole body dose by de-termination of tritium in urine NIS 597 and in the HSE guidance for approved dosimetry services on individual monitoring of internal radiation from the pro-longed retention of long-lived radionuclides5 Calibration of the dosimetry system

25

Criterion 8. The service shall, where relevant, use a calibration system which can be shown to be traceable to National Standards and the service shall be aware of the uncertainties associated with the calibration.

Guidance

on

criterion 8

8.1 The general guidance document6 gives advice on the appro-priate standard of calibration.

Reliability of service Criterion 9. The service shall make adequate arrangements for the timely despatch of dosemeters, devices, sample vessels, etc to employers and for the availability of sufficient and suitable processing or counting devices appropri-ate to the scope of the service.

Guidance

on

Criterion 9

Performance of readers and counting equipment 9.1 The dosimetry service should be capable of demonstrating that adequate readers and counting devices/equipment are available (in order to remain reliable and meet the timescales in this docu-ment), that they are subject to suitable performance checks, and rea-sonable provision has been made for dealing with breakdowns in this equipment. Provision for the breakdown of equipment could include arrangements with the equipment supplier for repair or temporary re-placement.

Dose assessment Criterion 10. The service shall either: (a) make use of established principles and models for dose assessment calculations; or (b) justify the dose assessment calculations it uses, including in particular, assumptions made about various factors such as the environmental equilibri-um of parent and daughter radionuclides, the effectiveness of personal protec-tive equipment, the time of intake and particle size.

26

Guidance

on

Criterion 10

10. At the time of publication, the dose coefficients and underlying bi-okinetic and dosimetric models that should be used are those provid-ed in ICRP 119. However, ICRP have published new biokinetic and dosimetric models and dose coefficients in their Occupational Intakes of Radionuclide series of Publications (ICRP 130, 134, 137 & 141). Which should be used when they are formally adopted. However, al-ternative approaches to dose assessment are possible. The parame-ters used for the biokinetic and dosimetric models may be modified to take account of material-specific and workplace-specific data where this can be justified, for example on particle size distribution or ab-sorption characteristics

10.2 Radon and its short-lived decay products are dealt with sepa-rately in ICRP publication 137. Services assessing doses from expo-sure to radon and its decay products may use a conversion coeffi-cient of 1.4 mSv per mJ h m-3 to calculate doses from exposure to ra-don. Where concentrations of radon gas are measured over an ap-propriate period the service will need to justify the equilibrium factor used.

Guidance

on

Criterion 10

10.3 In some cases, particularly those where an initial dose is re-ported based on air sampling data, it is accepted that the service may use secondary limits eg ALI and DAC although such an approach is not encouraged. In this case the relevant ALI for a radionuclide will be obtained by dividing the annual dose limit of 20 mSv (0.02 Sv) by the relevant effective dose coefficient e(50). In such cases, the ser-vice may choose to report the 'compliance index' and relevant dose limit to ADS (Records), rather than the assessed dose. However, HSE would strongly prefer an assessment to be made of the dose re-ceived, rather than ‘compliance index’, wherever possible.

Criterion 11. The service shall use appropriate methods of dose assessment to enable estimates of: (a) the 50-year committed effective dose, E50, or the 50-year committed equivalent dose, HT(50), to a named tissue (T), or (b) the 'compliance index' and relevant dose limit for the whole body, to be reported to ADS (Records), using the values and relationships specified in Annex I where appropriate.

Guidance

on

Criterion 11

Compliance index 11.1 The term ‘compliance index’ is fully explained in HSE’s publica-tion on monitoring for long-lived and long-retained radionuclides5.

Reassessment of doses Criterion 12. The service shall make adequate arrangements for the secure storage of relevant measurement data and dose assessment calculations for a

27

minimum of two years (five years in the case of persons subject to a five year dose limit) after the calculations are made, to enable calculations to be reas-sessed in the light of a query or new information.

Guidance

on

Criterion 12

12.1 The service will need sufficient records of measurement data and parameters used in order to repeat these calculations when nec-essary.

Advice to clients Criterion 13. The service shall provide written advice to clients about: (a) the proper handling and operation of air monitoring equipment; (b) the issue, care and storage of personal dosemeters, air samplers and bio-assay sample vessels; (c) methods of avoiding contamination of filters and samples; and (d) any other necessary information.

Guidance

on

criterion 13

13.1 The written advice to the employer would normally cover matters such as:

• recommended dosemeter/PAS/sample vessel issue and return procedures, including specific arrangements to ensure that named persons are unmistakably linked to the dosemeters they wear or samples they provide

• any training, instruction and supervision recommended for classi-fied persons required to wear PAS or to provide samples

• period of monitoring or quantity of sample required

• the need to distinguish the arrangements for taking samples from non-classified persons from arrangements relating to classified persons so there is no confusion about which doses must be re-ported to ADS (Records)

• storage arrangements for PAS filters and/or bio-assay sample vessels to minimise the possibility of cross contamination

• frequency of provision of bio-assay samples

• arrangements for dealing with unusual occurrences e.g. late or contaminated samples

• the need to inform the ADS immediately a classified person leaves employment to ensure that dosemeters etc are no longer issued and erroneous dose assessments are not transferred to the dose records by ADS (Records); and also to enable the latter to issue a termination record.

Reporting results to other ADS Criterion 14. The service shall make adequate arrangements for data transfer to ADS (Records) or, where the service is only approved for part of the dose

28

assessment procedure, to another ADS (Assessment). These arrangements shall involve specified means of data transfer by authorised persons with ade-quate provision for security of the information against corruption or loss. The arrangements should ensure that the information in criterion 15 can be provid-ed to ADS (Records) in a clear, legible manner within a reasonable period.

Guidance

on

Criterion 14

Reasonable period 14.1 Except for dose assessments relating to intakes of long-lived radionuclides, "reasonable period" would generally be 14 days from the receipt of the relevant air monitoring, bio-assay sample, or radon dosemeter or from when the relevant in-vivo measurement was made. 14.2 In the case of long-lived radionuclides retained in the body for prolonged periods, or other radionuclides requiring a series of meas-urements to be made over more than five days for each assessment, "reasonable period" would generally be 28 consecutive days from the date on which the last sample was received or the first in-vivo meas-urement was made. However, it is recognised that a longer period would be appropriate for those cases where more bio-assay meas-urements are required to provide a sufficient estimate of dose (see HSE publication on long-lived radionuclides5). In these cases, the dosimetry service should have arrangements for notifying ADS (Rec-ords) of an interim assessed dose (e.g. from air monitoring data) or, where this would be inappropriate, of informing ADS (Records) why the dose information for the relevant assessment period has been de-layed. 14.3 HSE recognises that in some cases the best assessment of dose from long-lived long-retained radionuclides can only be obtained after a number of steps. Therefore, relevant dosimetry services are permitted, as a condition of approval, to report revised dose assess-ments to ADS (Records) when better information becomes available. However, this is not meant to infer that such ADS must review all his-torical dose information and report best estimates of dose in each case. The condition of approval merely permits the ADS to report a revised dose assessment. 14.4 Nevertheless, where it is believed that the dose actually re-ceived by a classified person was much greater than or much less than that shown in the dose record the employer will need to consider a special entry in the dose record in accordance with regulation 23 IRR17. 14.5 The time periods mentioned above exclude Bank Holidays.

29

Auditing data

14.6 The output from the dosimetry system may be transferred electronically to ADS (Records), particularly where this is part of the same organisation. In such cases, ADS (Assessment) should be able to demonstrate that there is a reliable system of checking dose assessments by an authorised person before the results are trans-mitted. ADS (Assessment) should also be capable of transferring data in written or other suitable form to ADS (Records) if the need arises. If the service does not have this capability the Approval Body

will limit the approval accordingly.

Guidance

on

criterion 14

(continued)

Single-employer ADS 14.7 If the ADS (Assessment) only reports dose assessments for the classified persons of a single employer the name and address of the employer can be omitted from the report to ADS (Records) but the approval will be limited accordingly.

Criterion 15. The service shall ensure that the information reported to ADS (Records) includes: (a) a unique identifier (eg National Insurance Number) and the surname and initials of the classified person for whom the dose assessment has been made; (b) name and address of the employer; (c) the radionuclide(s) for which dose assessment was made; (d) exposure period to which the dose assessment relates (eg 1 June 2020 to 30 June 2020 inclusive); (e) particulars of any assessment of either:

(i) E50, or HT(50) , as appropriate, or (ii) the 'compliance index' and relevant dose limit for the whole body; (a) an explanation of any abbreviations or code letters used; and (b) any special observations.

Guidance

on

criterion 15

Unique identifier 15.1 A personal identifier other than NIN can be used providing it is unique (works numbers may not be unique if they can be used by future employees) and there is an unambiguous link to NIN which is reported to ADS (Records) separately.

30

Guidance

on

criterion 15

(continued)

Below detection threshold 15.2 Where a measurement indicates that the dose would be be-low the detection threshold for that technique, then the dose may be reported as bdt (below detection threshold), with the employer's agreement. There is no obligation on services to use 'bdt' Where 'bdt' is reported the corresponding value of dose should be stated in the report sent to the ADS (Records), but ADS (Records) will be ex-pected to treat the dose as zero.

Below recording level

15.3 Some techniques of measurement and dose assessment are of such sensitivity that doses below 1% of the relevant proportion of the dose limit for the period can be estimated. When a decision has been taken to assess a particular component of dose and an individ-ual measurement for the period indicates that the dose would be less than 1% of the proportion of the total annual dose limit for the rele-vant period, the ADS may, with the prior agreement of the employer and the ADS (Records), dispense with a computation of dose for the relevant period. In such a case the report to the ADS (Records) should give the results as brl (below recording level) and the value of brl should also be stated. It is equally acceptable to report a dose of zero to ADS (Records).

Unassessed doses

15.4 ADS should not normally report a zero dose for components of dose that were not assessed, for example a bio-assay sample was not obtained for that period because the individual was not at work for that period. It should be clear to ADS (Records) which dose types are being reported. It is acceptable to report compliance index (see HSE publication on long-lived radionuclides5) provided that the rele-vant dose limit is also reported and it is made clear to ADS (Records) what the information means.

Dosimetry services only approved for assessing intakes

15.5 If a service is only approved for part of the dose assessment process (e.g. measurements of tritium concentration in urine) it will be sufficient for that service to report 'activity', 'intake' or other appropri-ate information provided that the dosimetry service approved to make the assessment of dose can use the information supplied to make such assessment.

Reporting dose assessments in the event of an accident, incident or occur-rence Criterion 16. The service shall be capable of reporting forthwith to the em-ployer, on request, the assessed dose for any individual involved in an acci-dent, incident or occurrence where the employer suspects that the individual is likely to have received a committed effective dose exceeding 6 mSv or 3/10ths of a relevant dose limit.

31

Criterion 17. The service shall be capable of reporting forthwith to the em-ployer any assessed dose in a single dose assessment period that exceeds any relevant dose limit.

Guidance

on

criterion 17

17.1 "Reporting forthwith" would normally be taken to mean report-ing as soon as the results of measurements are available (e.g. by fax or telephone) followed up by written confirmation as soon as the initial dose assessment has been completed.

Late return of samples or dosemeters and receipt of contaminated samples Criterion 18. The service shall make suitable provision for reporting to ADS (Records) in circumstances where it is not possible to provide an assessed dose for an individual in any particular assessment period.

Guidance

on

criterion 18

18.1 Wherever possible the ADS requests the employer to ar-range for a repeat or additional sample/measurement (bio-assay/in-vivo counting) to replace the sample lost/contaminated or not provid-ed. 18.2 There is no provision in IRR17 for an ADS (Records) to enter a notional dose in the statutory dose record in such an event without the involvement of the employer. Appendix 2 gives further advice.

Periodic performance tests Criterion 19. Accordance with HSE's published protocols with a UKAS accred-ited test-house, and shall provide to the Approval Body a copy of the report of such a performance test at intervals not exceeding 18 months.

Guidance

on

criterion 19

19.1 The performance test which some types of internal dosimetry service are required to undertake is an important aspect of overall QA. Details of each of the performance tests are given in protocols issued by HSE.

32

Guidance

on

criterion 19

(continued)

19.2 The results will be assigned by the test house to one of three bands: (a) 'Band A' results are a pass and no further action is required (b) 'Band B' results are acceptable for a periodic test, but not for

a new application for approval; an ADS obtaining Band B re-sults in a periodic performance test is required to undertake a review

(c) 'Band C' results are a fail; in this case the ADS is required to

undertake a review and submit a report with an action plan to the Approval Body.

19.3 It follows that the failure of a service to achieve a 'Band A' test result warrants further investigation by that service. The in-service review may be quite limited in scope if it is clear why the per-formance test results fell outside 'Band A'. An action plan should be drawn up to implement the improvements over a reasonable time-scale.

Criterion 20. In any case where the results of a periodic performance test ar-ranged for the purposes of criterion 19 fall into Band B or Band C, as specified in HSE's current statement on the approval of dosimetry services, the service shall carry out an in-service review of performance and produce a written re-port on the findings. If the test results fall into Band C, a copy of the report shall be sent to the Approval Body. In either case, the review should focus on the reasons the service failed to achieve test results in 'Band A' and it should result in recommendations for improvements where appropriate. An action plan should be drawn up by the ADS, and included in the report, to implement the necessary improvements within a reasonable period of time.

Guidance

on

criterion 20

20.1 An ADS which has failed a performance test and submitted its action plan to the Approved Body may choose to undertake a fur-ther test to demonstrate that the improvements it has made have been effective. In such cases, if a copy of a successful test certificate is sent to the Approval Body within the three month period referred to in section 2 paragraph 23 the next performance test will not be re-quired until 18 months from the date on that certificate..

33

Annex to HSE criteria for approval (see criterion 11) Where the effective dose from internal external radiation (Eext) is estimated directly it

is defined by the expression:

E = T WT HT =

T WT

R WR D T,R

where - DT,R is the absorbed dose averaged over the tissue or organ T, due to radia-

tion R - WR is the radiation weighting factor and - WT is the tissue weighting factor for tissue or organ T. Appropriate values of tissue weighting factor (WT) to be used to weight the commit-ted equivalent dose in a tissue or organ (T):

Tissue or organ Tissue weighting factor

Gonads 0.08

Bone marrow (red)

0.12

Colon 0.12

Lung 0.12

Stomach 0.12

Bladder 0.04

Breast 0.12

Liver 0.04

Oesophagus 0.04

Thyroid 0.04

Skin 0.01

Bone surface 0.01

Remainder 0.05*

(*) For the purposes of calculation, the remainder is composed of the following

additional tissues and organs: adrenals, gall bladder, heart, , kidneys, lym-phatic nodes, muscle, pancreas, oral mucosa, pancreas, prostate, small intes-tine, spleen, thymus, uterus/cervix and extrathoracic region. .

.

34

Values of radiation weighting factor, WR, depend on the type and quality of the radi-ation field.

Type and energy range Radiation weighting factor, WR

Photons Electrons and muons Neutrons, energy , < 1MeV 1 MeV ≤ En ≤ 50 MeV En > 50 MeV Protons and charged pions Alpha particles, fission fragments, heavy ions

1 1

2.5 + 18.2 e-[ln(En)]²/6 5.0 + 17.0 e-[ln(2 En)]²/6

2.5 + 3.25 e-[ln(0.04 En)]²/6 2

20

35

References 1. Requirements for the Approval of Dosimetry Services under the Ionising Ra-

diations Regulations 2017: Part 1 External Radiations. RADS 1. HSE. 2. Requirements for the Approval of Dosimetry Services under the Ionising Ra-

diations Regulations 2017: Part 3 Co-ordination and Record Keeping. RADS 3. HSE.

3. HSE Information sheet 'Radiation doses - assessment and recording'. Ionis-

ing Radiation Protection series No 2. HSE. 4. The Ionising Radiations Regulations 1999. Statutory Instrument 1999 No

3232. HMSO. ISBN 0-11-085614-7 5. Guidance for Approved Dosimetry Services. Individual monitoring of internal

radiation from the prolonged retention of long-lived radionuclides. HSE. 1998

6. General Guidance for Laboratories providing Personal Dosimetry Services. RADS/G HSE.

7. NAMAS. Requirements for Laboratories Providing Dosimetry Services. The

assessment of whole body dose by the determination of tritium in urine. NIS 59 November 1991. Available from UK Accreditation Service.

36

Appendix 1 to RADS 2

Statement of Service for Internal Radiations The statement of service submitted on application for approval or at the time of re-assessment should contain the following information. References to published in-formation and supporting documents which are not part of this statement will be ac-ceptable , provided those references etc contain the necessary information, but do-simetry services should be prepared to provide copies if requested by the Approval Body. Details are not required about those aspects of the service which only con-cern persons who have not been classified under regulation 21 IRR 17. General 1. The name and address of the service. 2. The scope of the application including: the type of service for which approval is sought and the principal radionuclides or class(es) of radionuclides intended to be assessed. 3. An overview of the service showing how it satisfies criterion 1, including: (a) an indication of the normal through-put of the service (the number of dummy samples per month used for training can be shown where normal through-put for en-try onto the statutory dose record is very low) and the likely number of classified per-sons for whom the service will be provided (b) an outline description of the administrative and laboratory facilities and ar-rangements for the storage, despatch, reception, handling and processing of dose-meters, PAS etc and for communicating dose assessments (or contribution to such assessments); (c) details of the management systems for ensuring that these arrangements are followed so that the service produces a reasonable degree of accuracy, is highly re-liable and communicates accurate information within the timescales required; (d) the name, qualifications and relevant experience of the person in charge of the service and their deputy or deputies; and (e) details of the training for new staff about the procedures used for dose as-sessment etc 4. A brief explanation of the steps taken to meet the standards in HSE publica-tion ‘General guidance providing personal dosimetry services’ relevant to that service (Criterion 2).

37

Quality assurance (criterion 3) 5. An overview of the quality assurance procedures required by for monitoring performance with reference to detailed supporting documents Methods of dosimetry (criteria 4 and 5) 6. An overview of the method for assessing individual doses including the types of measurements used to estimate intakes of the principal radionuclides for which approval/continuing approval is sought, the strategy employed to use these meas-urements to assess chronic and acute intakes and the models used to assess the 50-year committed dose from those intakes. Assessment of intakes (criteria 6 and 7) 7. Outline descriptions of the proposed techniques of measurement for the prin-cipal radionuclides or class(es) of radionuclides being assessed - including any au-diting of the client employer’s arrangements - and the expected routes of intake for those radionuclides with details of the following given in referenced supporting doc-uments (a) bio-assay (i) arrangements for sample collection/reception; (ii) sample preparation; (iii) arrangements to avoid contamination of samples within the laboratory; (iv) technical specification for sample analysis; (v) arrangements for conforming to NAMAS publication NIS 59 where appropri-ate. (b) in-vivo counting

(i) technical description of the measurement system geometry, methods of back-ground reduction and data processing systems to detect the activity of the radionu-clides of interest; arrangements to avoid interference due to contamination of body surfaces. (c) air monitoring (i) assessment of airborne activity characteristics (including equilibrium factors in the case of radon decay products); (ii) criteria for wearing personal air samplers (PAS);

38

(iii) justification (where relevant) for use of static air samplers (SAS) when PAS is not to be worn continuously; (iv) methods of determining appropriate SAS locations, stable PAS/SAS ratios and of defining occupancy zones on this basis (the sampling period used to deter-mine the ratio should be given); (v) details of any "workplace protection factor" claimed in areas where respiratory protective equipment is used and the employer's justification for the use of this factor (where PAS/SAS measurements are modified to take account of this factor); (vi) technical specification of air sampling equipment and measurement system (or dosemeter); (vii) arrangements for conforming to standards in HSE guidance for the prolonged retention of long lived radionuclides. Calibration (criterion 8) 8. Outline details of relevant calibration arrangements and identification of main sources and magnitude of uncertainties. Reliability (criterion 9) 9. A description of the arrangements for ensuring timely despatch and collection of sample vessels, filters etc and arrangements for analysing samples, filters etc or making measurements on individuals so that dose assessments can be made and reported within expected timescales. Dose assessment (criteria 10 and 11) 10. Description of dose assessment calculations including, where relevant: (i) the metabolic and excretion models used; (ii) the derivation of any secondary control limits where these are still necessary, eg DAC and ALI "; and (iii) step-by-step calculations for dose assessments following chronic and acute intakes over various likely dose assessment intervals or arrangements for using proven and validated software for making these assessments.

39

Reassessment of doses (criterion 12) 11. Arrangements for recording and storing samples (where appropriate) and the results of measurements and recorded dose assessment calculations The following matters should be described: (a) the arrangements for recording the results of measurements and assess-ments; (b) dose quantities used for dose assessments; (c) arrangements for preserving records, including the period of retention Advice to clients (criterion 13) 12. Details of any guidelines given to clients e.g. about the storage and security of samples to prevent contamination Reporting results to other ADS (criteria 14 and 15) 13. A description of the arrangements for data transfer to ADS (Records) to en-sure that the required information is clear, checked to ensure it is free from corrup-tion and meets the required timescales. Please indicate if the service intends to re-port results other than 50-year committed effective dose and include a copy of the standard dose reporting form or other indication that criterion 15 will be met. Also, where approval/continuing approval is sought for prolonged retention of long lived radionuclides please describe the procedure for reporting improved internal dose as-sessments to ADS (Records) Reporting results in the event of an accident etc (criteria 16 and 17) 14. A description of the arrangements for reporting these events to the employer as appropriate Late return of samples etc (criterion 18) 15. Default arrangements by the dosimetry service for dealing with late, lost or contaminated samples and procedure for investigation by the ADS of any 'abnormal' dosimetric results which could have arisen from a breakdown in procedures within the service The service should include a description of results which it would con-sider abnormal. Periodic performance tests (criteria 19 and 20) 16. Details of arrangements for undertaking these tests as appropriate. Appli-cants should provide a copy of Band A test results relating to a test undertaken with-in the previous 3 months by the service if a test is required in HSE’s current state-ment on approval of dosimetry services. Those seeking continuing approval should have provided copies of relevant reports of performance tests at intervals not ex-

40

ceeding 18 months and in addition evidence of in-service reviews and action plans where required by criterion 20.

41

Appendix 2 to RADS 2

Notional and Estimated Doses 1. The following advice only relates to classified persons for whom the ADS is making dose assessments under the Ionising Radiations Regulations 2017 (IRR17). 2. It is the duty of the employer to ensure that assessments are made of all sig-nificant doses. Therefore, it is the employer who must ensure that: (a) all samples (or dosemeters) required for a dose assessment period are sent to ADS (Assessment) promptly at the end of that period; and

(b) all classified periods required to present themselves for in-vivo counting do so when required. 3. Statutory dose records should be compiled using systematic measurements and assessments of doses made by the ADS (Assessment) under Regulation 22 of the IRR17. The only exceptions to this are provided by Regulation 23(1) IRR17 in cases where a sample (or dosemeter) is lost or destroyed, or where the ADS (As-sessment) cannot assess the dose received, for example, as a result of obvious con-tamination of a sample. In such cases it is the duty of the employer to make an in-vestigation consulting with the Radiation Protection Adviser as appropriate, and ei-ther: (a) estimate the dose and arrange for the ADS (Records) to enter the "estimated dose" in the relevant dose record supplying the ADS with a summary of the infor-mation used to estimate that dose; or (b) exceptionally, where this is not possible, arrange for the ADS (Records) to en-ter a "notional dose" in the relevant dose record. 4. However, in most cases it should not be necessary to carry out an investiga-tion provided that the employer can arrange for the individual concerned to provide another sample or present themselves for in-vivo counting (as appropriate). If this cannot be done, or is inappropriate for the type of dose assessment required, the employer will need to take action under Regulation 23(1) of IRR17. 5. There is no provision in the Regulations for ADS (Records) to enter a "notion-al dose" in a dose record without the agreement of the employer. However, it is rec-ognised that gaps will appear in dose records if employers fail to return samples (or dosemeters). This will lead to problems with dose summations and may cause diffi-culties for the employer in the effective exercise of dose control. Therefore, it is in the employer's interest to resolve this problem. 6. The ADS is required to have a default procedure for dealing with late, lost or contaminated samples (or dosemeters) or failure of a classified person to present themselves for in-vivo counting. The procedure should be capable of adaptation to suit the needs of the particular employers and ADS (Records). It is recommended that this procedure takes the following form:

42

(a) ensure that the procedure for responding to the non-return of samples (or dosemeters) or the receipt of contaminated samples is written into the general terms of the contract between the ADS and the employer (charges may need to reflect the costs of enquiries about missing samples); (b) require the employer to indicate on the list of samples taken (or due to be tak-en) for the period, which samples are missing or destroyed or being repeated (where relevant) and which of these are likely to be assigned an estimated dose; (c) contact the manager designated by the employer, promptly e.g. by telephone or fax, if no action has been taken either to return any missing or repeated samples (or dosemeters), or confirm the assignment of an "estimated" or "notional" dose to ADS (Records) by the end of the following assessment period; (d) write to the employer formally to request the return of the sample (or doseme-ter) if no action is taken by the manager- see example letter attached; (e) report promptly to the employer, receipt of any contaminated samples which cannot be assessed, requesting a repeat sample as appropriate; (f) report to ADS (Records) by suitable means e.g. specific code letter in the dose report when a sample relating to an individual is missing.

7. Advice for ADS (Records) is given in Part 3(2).

43

Annex to Appendix 2

Draft Letter

Dear NON-RETURN OF SAMPLE/DOSEMETER (NAME OF CLASSIFIED PERSON) Because you have not returned a sample/dosemeter for [Name of classified person] ................. .................................................. (National Insurance No ) we are unable to report a dose assessment for the period ............. to .................. to the Approved Dosimetry Service (Co-ordination and Record-Keeping). You should therefore return the sample (or dosemeter) at once if it is available or ar-range for a repeat sample to be provided by the individual. If the sample/dosemeter is lost or destroyed and a repeat sample cannot be provided for dose assessment purposes, you should make an investigation of the circumstances under Regulation 23(1) of the Ionising Radiations Regulations 2017 to estimate the dose received by the above-named person and advise the Approved Dosimetry Service (Co-ordination and Record-keeping) forthwith. Yours sincerely Head of Approved Dosimetry Service