OEWG Dosimetry Subgroup

Issue A number of potential issues were identified at the Occupational Exposures Working Group meeting on 11 November 2014 relating to HSE’s intentions in implementing the Basic Safety Standards for radiological protection Directive (BSSD) requirements and their impact on dosimetry. The issues themselves are detailed in the annexes to this paper.

HSE proposed the formation of an OEWG subgroup to discuss these specific issues in greater detail.

Membership The following stakeholders have requested to be part of this subgroup:

Name Organisation Claire Chapple NHS Mary Allen AWE Roger Collison Babcock Sharan Packer NHS Robin Wells DSTL Phil Gilvin PHE Christine Wilson Sellafield Kobina Lokko ONR

Proposal HSE proposes to hold a 4 hour meeting with lunch on the 7th September 2015, in Redgrave Court, Bootle. This will aim to discuss the issues raised in the annexes, with the intention of reaching agreement on a way forward for implementation by the end of the meeting.

There may be a need to arrange a follow up meeting on one or several of the issues discussed by the Dosimetry Subgroup. This will be discussed at the end of the first meeting.

The agreed outputs from the meeting and any subsequent discussions will form the basis of firmer HSE proposals to implement the BSSD and for the HSE Impact Assessment that will be presented alongside any formal HSE implementation proposal.

Proposed Agenda 1. Introductions / Intentions of the Day 2. Dosimetry discussions a. Article 41 – HSE interpretation b. Dose records – costs associated c. Radiation Weighting Factors – possible impacts d. Data Monitoring systems – additions to existing practices e. Separate accidental dose recording f. Other issues – understanding check 3. Assessing the impact - HSE economists 4. Conclusions / Next Steps/ Follow up Annex 1 – Article 41

Issue At the OEWG Meeting in November 2014, the requirements of Article 41 were discussed as a potential issue. Article 41 Individual monitoring 1. Member States shall ensure that category A workers are systematically monitored based on individual measurements performed by a dosimetry service. In cases where category A workers are liable to receive significant internal exposure or significant exposure of the lens of the eye or extremities, an adequate system for monitoring shall be set up. 2. Member States shall ensure that monitoring for category B workers is at least sufficient to demonstrate that such workers are correctly classified in category B. Member States may require individual monitoring and if necessary individual measurements, performed by a dosimetry service, for category B workers. 3. In cases where individual measurements are not possible or inadequate, the individual monitoring shall be based on an estimate arrived at from individual measurements made on other exposed workers, from the results of the surveillance of the workplace provided for in Article 39 or on the basis of calculation methods approved by the competent authority.

Article 41.3 was specifically highlighted as being the subject of a subtle change of emphasis that could result in changes needing to be made to existing UK approaches, specifically the new option of individual measurements being made on the basis of calculation methods approved by HSE.

There were also specific concerns raised about how Article 41.3 would be applied to non- classified outside workers. Do stakeholders think this applies given that Article 41.2 gives the option of individual monitoring?

Proposal

Article 41.3 being applied to non-classified outside workers Article 41.2 states that Member States may require individual monitoring, and if necessary individual measurements performed by a dosimetry service for non-classified (Category B) workers. HSE can confirm that it is not our intention to require individual monitoring or measurements for non-classified workers. As such, we do not believe that the provisions for A41.3 will be required for non-classified workers, as IRR99 will not require individual monitoring for non-classified workers.

Where a dutyholder has decided to perform individual monitoring or measurements for a non-classified workers, the decision on how to determine to an estimate for the non- classified workers’ dose is at the dutyholders’ discretion.

Estimating doses on the basis of calculation methods approved by HSE Through RADS, HSE has already approved the use of alternative calculation methods in a small number of instances. It is these approvals which can now be specifically used in determining estimated individual measurements.

HSE believes that the inclusion of the option to base estimated individual measurements on the basis of calculation methods approved by HSE offers more choice to the ADS to determine the appropriate estimated dose, but this option will only be relevant in the very few instances where calculation methods have been approved by HSE. Questions for stakeholders 1. Do OEWG members agree with the interpretation of Article 41? 2. Can OEWG members identify any instances where estimated individual measurements solely from calculation methods approved by the HSE will be used? a. If so, how many radiation workers are affected? b. If so, how long does it take to estimate an individual measurement using this methodology? Annex 2 – Costs associated with the retention of dose and medical records

Issue At the OEWG Meeting in November 2014, HSE presented a proposal to reduce the medical and dose record retention period from 50 years to 40 years (Proposal M2 – Dose and medical retention period). Stakeholder feedback on the day was that HSE’s estimate of costs on this issue could be refined.

HSE estimated that the cost of keeping a dose record was £17.50 per year. OEWG stakeholders assumed (without confirming the accuracy of the £17.50 figure) that HSE was counting the cost of keeping an active dose record, which OEWG members felt was not an accurate indicator of the costs incurred from retaining historic dose records. OEWG stakeholders also made the point that deleting individual dose records on annual basis based on their being over the retention period may actually cost more than retaining the overall record.

Questions for OEWG stakeholders 1. How much does it cost to retain an historic dose record? a. Who pays for this – the company who employed the individual, or are these maintenance costs factored into the active dose record costs? 2. How much time would it take to delete annual historic dose records from an individual dose record? 3. What level of employee would undertake this work? a. What would their estimated hourly rate be? 4. How many of these historic records do you hold, as a percentage of your overall dose records for individuals? 5. Is the situation similar for medical records? Are they factored into the dose record?

Proposal

Costs associated with the retention of dose and medical records HSE proposes to use the responses to the questions above to draft a more detailed impact estimate of the HSE proposal to reduce the retention period to 40 years. If these questions are asked in good enough time before the date of the meeting, then the results can then be discussed at the OEWG subgroup itself.

Removal of 75 year age criterion? OEWG asked HSE, given the increase in worker retirement age, whether the 75 year age criterion should be retained. HSE proposes to keep this criterion, as it is a clear requirement in the BSSD, and therefore HSE will need to demonstrate how this requirement has been transposed. Annex 3 –Weighting Factors

Issue The Weighting Factors in IRR99 will need to be slightly altered to implement the new BSSD. It is unclear at this stage what effect these changes will have in:  the costs to ADSs to use the new weighting factors in their calculation methods; and  the dose consequences to radiation workers whose doses are calculated via these weighting factors.

Radiation Weighting Factors

New BSSD text IRR99 text IRR99, Appendix 1 Radiation weighting factors Radiation weighting factors Where required for a direct estimate of E, values Radiation type wR of radiation weighting factor, WR, depend on the type and quality of the external radiation field. Photons 1 Type and energy range Radiation weighting

factor, WR Electrons and muons 1 Photons, all energies 1 Electrons and muons, 1 Protons and charged 2 all energies pions Neutrons, energy, < 10 5 keV Alpha particles, 20 10 keV to 100 keV 10 fission fragments, > 100 keV to 2 MeV 20 heavy ions > 2 MeV to 20 MeV 10 > 20 MeV 5 - Neutrons, En < 1 MeV 2.5 + 18.2 e Protons, other than 5 [ln(En)]²/6 recoil protons, energy > 2MeV -[ln(2 Neutrons, 1 MeV ≤ En 5.0 + 17.0 e Alpha particles, fission 20 ≤ 50 MeV En)]²/6 fragments, heavy nuclei - In calculations involving neutrons it may be Neutrons, En > 50 2.5 + 3.25 e MeV [ln(0.04 En)]²/6 preferable to use: WR = 5 + 17e-(ln(2E)) Note: All values relate to the radiation incident where E is the neutron energy. on the body or, for internal radiation sources, HSE may authorise the use of equivalent emitted from the incorporated radionuclide(s). methods for estimating E.

Questions for OEWG stakeholders 1. Will the highlighted changes to radiation weighting factors be difficult to implement in changing how ADSs calculate doses? 2. Will the changes to the new BSSD figures have a significant impact on how doses are calculated? a. Will these changes have a significant impact on particular types of radiation work? 3. How often are these weighting factors used now? a. How many workers are affected? 4. What would the main costs of implementation be?

Tissue Weighting Factors

New BSSD text IRR99 text Tissue Weighting factors IRR99, Appendix 1 Tissue weighting factors Tissue w Tissue or organ Tissue weighting factor T Gonads 0.2 Bone marrow 0.12 Bone-marrow (red) 0.12 (red) Colon* 0.12 Colon 0.12 Lung 0.12 Stomach 0.12 Lung 0.12 Bladder 0.05 Breast 0.05 Stomach 0.12 Liver 0.05 Oesophagus 0.05 Breast 0.12 Thyroid 0.05 Skin 0.01 Remainder tissues* 0.12 Bone surface 0.01 Remainder 0.05 (†)(††) Gonads 0.08 Appropriate values of tissue weighting factor Bladder 0.04 (WT) to be used to weight the equivalent dose in a tissue or organ (T), where necessary. Oesophagus 0.04 * Dose to the colon is taken to be the mass weighted average dose to the upper and Liver 0.04 lower large intestines. † For the purposes of calculation, the remainder Thyroid 0.04 is composed of the following additional tissues and organs: adrenals, brain, small Bone surface 0.01 intestine, kidneys, muscle, pancreas, spleen, thymus, uterus and extrathoracic airways. Brain 0.01 †† The equivalent dose to the remainder tissues is normally calculated as the mass-weighted Salivary glands 0.01 mean dose to the ten organs and tissues listed Skin 0.01 above. In the exceptional case in which the most highly irradiated remainder tissue or organ * The w for the remainder tissues (0.12) applies T receives the highest equivalent dose of all to the arithmetic mean dose of the 13 organs and tissues for each sex listed below. Remainder organs, a weighting factor of 0.025 (half of tissues: adrenals, extrathoracic (ET) region, gall remainder) is applied to that tissue or organ and bladder, heart, kidneys, lymphatic nodes, 0.025 to the mass weighted equivalent dose in muscle, oral mucosa, pancreas, prostate (male), the rest of the remainder tissues and organs. small intestine, spleen, thymus, uterus/cervix (female).

HSE notes the differences between IRR99 and new BSS –  Breast – higher factor (0.05 – 0.12)  Remainder tissues (0.5 – 0.12)  Gonads – lower factor (0.2 – 0.08)  Bladder – lower factor (0.05 – 0.04)  Oesophagus – lower factor (0.05 – 0.04)  Liver – lower factor (0.05 – 0.04)  Thyroid – lower factor (0.05 – 0.04)  Brain – new factor  Salivary glands – new factor

There is also less explanatory text.

Questions for OEWG stakeholders 1. Will the changes detailed above to tissue weighting factors be difficult to implement in changing how ADSs calculate doses? 2. Will the changes to the new BSSD figures have a significant impact on how doses are calculated? a. Will these changes have a significant impact on particular types of radiation work? 3. How often are these weighting factors used now? a. How many workers are affected? 4. What will the main costs of implementation be?

Proposal These levels are set in the new BSSD and are required to be adopted – finding out more on the impact of the change is needed. Annex 4 – Data monitoring systems – nationality and unique identification number

Issue At the OEWG Meeting in November 2014, HSE acknowledged that the BSSD sets out requirements for record keeping (Annex X) that differ from existing IRR99 requirements (Proposal M7 – Data monitoring systems). The requirements that are new were identified as:  Data monitoring systems containing information on the nationality of the worker  Data monitoring systems containing information on the worker’s unique identification number

It was also pointed out that the radiation passbooks of Outside Workers would also need to demonstrate compliance with these new requirements for nationality and unique identification number.

HSE acknowledged that these requirements may require changes to ADS databases and the OW radiation passbook template, and that these changes will cost.

HSE acknowledges that the OW radiation passbook template will need to be revised to take account of these new data fields. As an interim measure, would HSE be able to issue an amendment to the form with space for the requisite information as a sticker to be placed on all existing radiation passbooks to demonstrate compliance with the Directive requirements?

With respect to the unique ID number, the HMRC website (http://www.hmrc.gov.uk/manuals/nimmanual/nim39135.htm ) is clear that “The NINO is not proof of identity and must not be accepted as such”.

Questions for stakeholders 1. Does your ADS database contain a field for nationality? a. If not, what is your estimated cost to change the database to include this field? 2. Does you database use unique ID numbers? If so, what is usually used – is this the NI number or other identifier?

Proposal HSE proposes to use the responses to the questions above to draft a more detailed impact estimate of the HSE proposal to include these new fields as requirements for an ADS record. Annex 5 – Separate dose recording for accidents

Issue During discussions at the OEWG meeting in November 2014 it became clear that there was not consensus among members on whether accidental doses are recorded separately on individual dose records. HSE agreed to explore this issue with stakeholders.

As per Article 43.4, accidental doses are required to be recorded separately. This is not a new requirement, BSS96 Article 28 made similar requirements.

Questions for stakeholders 1. Do you separately record radiation workers accidental doses? What is your understanding on current regulatory requirements on this?

a. If not, how much do you estimate the requisite changes to the database will cost?

Proposal

The simplest approach would be to lift the relevant text from IRR Reg 25(3)) into IRR Reg 23? This then puts an onus for this to be recorded separately; however we need to find out about the cost implications of this.