Minutes of the Twenty-Fifth IRMF Meeting
Wednesday 21st May 2003
National Physical Laboratory
Present:
Chairman: Martyn Sené, National Physical Laboratory
Acting Secretary: Vic Lewis, National Physical Laboratory
There were 36 other members present from 21 establishments including:
| Amersham plc | AWE, Aldermaston | |
| BAE Systems Ltd | BNFL, Berkeley | |
| BNFL, Instruments | BNFL, Sellafield | |
| DERA Radiation Protection Service | Institute of Atomic Physics, Romania | |
| IRMC | JCS Ltd | |
| MDMSIPT | National Physical Laboratory | |
| NRPB, Chilton | PA Consulting | |
| RWE NUKEM, Harwell | RWE NUKEM, Winfrith | |
| Serco Assurance, Winfrith | Sherwood Nutec Consultancy | |
| Siemens Environmental Systems | Thermo Electron Corp | |
| UKAS |
Six members from a further five establishments had sent apologies.
Agenda Items
Neutron Monitoring Comparison
Vic Lewis (NPL) reported that the current exercise involved the circulation of a Mark 7 NRM and an NM2 monitor around five laboratories for calibration in fields produced by 241Am-Be and 252Cf sources with known emission rates. In addition, two laboratories would calibrate the monitors in 2.7 MeV monoenergetic neutron fields in a bilateral arm of the comparison.
Vic presented a series of figures summarising the results. There were some outliers that had arisen due to problems with correction for room scatter at larger source-to-detector distances. Another source of discrepancy was probably due to the age of some 252Cf sources. Generally speaking, these problems applied to conditions not used routinely for calibration purposes.
The results for the Mark 7 NRM had a spread of around 9% with 241Am-Be and 16% for 252Cf. With the NM2, spreads of approximately 10 % and 11% were observed for 241Am-Be and 252Cf respectively. These spreads are higher than obtained in the previous exercise partly because some 252Cf sources had not been calibrated for a long time. A large range of uncertainty values had been quoted.
A more detailed discussion was due to take place with the participants in the wash-up meeting that was being held following the present meeting. The final report was expected to be published by the end of June. Vic thanked the participants for their work on this exercise.
Comparison of surface contamination monitoring
John Bennett (DERA RPS) reported on the first meeting of the working group in February to plan the next exercise. Other members of the working group were Peter Burgess, Jan McClure and Clare Scott.
Laboratories would be expected to calibrate using their usual procedures. There would be little change in the protocol from that used previously. Participants would be allocated two-week slots for measurements. It was decided not to use check sources because of the difficulties of transporting them on and off participants’ sites.
The EP15 was chosen in order to help compare with results of previous exercises. To simplify investigation of the treatment of uncertainties, all participants would be asked to produce a full uncertainty budget for a calibration using 14C. It was decided to include a 44B as a photon monitor for the isotopes 55Fe and 129I. The DP8 plus Electra was chosen as the third instrument. Participants would be asked to use the contiguous proportions method for the DP8 plus Electra.
A further meeting of the Working Group was required to put the protocol together. In the meantime, laboratories were asked to let Clare Scott know if they wanted to participate.
Mike Woods (IRMC) thought that the proposed photon sources were low energy and did not represent the typical sources used by hospitals (in the 100 keV and above range). There was some discussion on this and it was agreed that there should be an action on Clare Scott to consult with hospitals on this matter before the next meeting of the Working Group.
Gamma Radiation Monitoring Comparison
Vic Lewis (NPL) reported that the results had been discussed at a wash-up meeting that was held following the previous IRMF meeting. The final report had been published as NPL Report CIRM 55, December 2002 and was available on the IRMF website.
Assuming that these comparisons were being held on a three-year cycle, the measurement phase of the next (fifth) IRMF gamma-monitoring comparison was not expected to begin until about October 2004. Therefore, appointment of the working group to plan that exercise would not be necessary until the next IRMF meeting at the earliest.
Future of IRMF Comparisons
A number of issues had been raised at and since the last IRMF meeting regarding IRMF policy related to comparisons. These included -
- naming of participants who reported late,
- issue of anonymity,
- disclosure of the identity of the participants whose data had been changed,
- clarification of the purpose of IRMF comparisons.
Martyn Sené (NPL) summarised the policy that had been formulated five years previously and the reasons behind it. It was felt then that linking names to results would create confidence in the user community but, on the other hand, this might tend to put off groups who were not confident. The consensus at the time was that withdrawal of results would not be allowed. This was in line with the policy for comparisons between national standards laboratories. The policy was that at the start of a comparison participants could opt to have their results identified or to remain anonymous. No subsequent change would be permitted. This two-option approach enabled less experienced laboratories to compare their abilities with the more established groups without the threat of being shown to be inaccurate.
The primary aim of IRMF comparisons was to improve measurement and calibration proficiency. Participation should be voluntary and IRMF should encourage as many organisations as possible to take part.
Mike Woods said that the policy for the national laboratories had worked well and was considered to be fair. Tony Richards thought the IRMF policy was entirely right in not excluding those who wished to remain anonymous. As their confidence increased they would then opt to be identified. Eddie Veater (UKAS) stated that one way for accredited laboratories to comply with the ISO 17025 requirements was to demonstrate through comparison that their results were consistent with those of other laboratories. UKAS accepted that the IRMF exercises should be used for this purpose. John Bennett thought that the policy regarding late reporting was necessary for the exercises to finish in a reasonable time.
The Chairman proposed that the present policy be continued. There were some practical details that would be left to working groups to deal with according to the circumstances of the individual cases concerned. There were no objections.
Distribution and Sale of Good Practice Guides
Martyn Sené reported that the DTI had agreed that it was much better to allow free access to GPGs rather than try to recover the costs. The following good practice guides in the ionising radiation area were now available as free downloads from the www (via the IRMF home page at www.npl.co.uk/irmf/).
Printed copies were available for sale from the NPL e-commerce website using the address www.npl.co.uk/e-store. Alternatively, they could be obtained from Michelle Sanderson (at radioactivity@npl.co.uk). There was a charge for printed copies to cover costs.
| GPG 14 | Examination, Testing and Calibration of Portable Rad. Prot. Instruments | £25 |
| GPG 29 | Examination, Testing and Calibration of Installed Rad. Prot. Instruments | £15 |
| GPG 30 | Practical Radiation Monitoring | £15 |
| GPG 34 | Radiometric Non-Destructive Assay | £25 |
| GPG 49 | The Assessment of Uncertainty in Radiological Calibration and Testing | £15 |
GPG 49, The Assessment of Uncertainty in Radiological Calibration and Testing
Mike Woods (IRMC) described the aims and scope of the GPG on uncertainties. The document contained an introduction on the theory of uncertainty, based on the international guide. There were technical sections dealing with uncertainties in protection level photon monitoring, neutron area survey monitoring and surface contamination monitoring. These contained examples. Within each area a typical calibration method was described and the individual uncertainty components were listed and discussed along with ideas for their estimation. Examples of uncertainty budgets were laid out in each section. The derivation of sensitivity coefficients was dealt with.
Mike emphasised that the purpose was to illustrate the guidance rather than be prescriptive. Readers had to assess what components were relevant to their own conditions and calculate the values for themselves. John Simpson (RWE NUKEM) thought that the values given in the guide were generally realistic.
Good Practice Guide on Air Monitoring
Max Pottinger (BNFL) reported that the Air Monitoring Users Group had met in September 2001 and November 2002 with a healthy attendance. A small group had been set up with a remit to produce a good practice guide on air monitoring. In its first meeting in February 2003, it had been agreed that the scope would concentrate on monitoring of particulates in the work place, air sampling and air monitors. It had been decided to exclude tritium at present – this position would be reviewed later. There would be appendices on detection limits and leakage testing. A section on uncertainties was envisaged.
It was planned to produce a first draft to go to the Working Group by the end of May. The second draft would go back to AMUG in November 2003. This would be the basis of a full consultation exercise. Hopefully, the third draft would be ready around February 2004. The end of the consultation period would be May 2004, with publication by October 2004.
Potential GPG on ADS Instruments and Electronic Personal Dosemeters (EPD)
Max Pottinger (BNFL) went on to say that one of the key points recognised by the AMUG GPG Working Group was that of personal air samplers; but this issue seemed to intrude into the area of approved dosimetry services (ADS). There was also the matter of EPDs; these were not covered by GPG 14. Max suggested that perhaps a good practice guide specifically dealing with these was required. There was a clear requirement for guidance in these areas. He had referred this matter to the External Radiation Dosimetry Group who were still considering the benefits of such a guide. It would be necessary to get HSE to accept the principle as well. Type test data was used to assess the suitability of instruments in this area, but Max did not envisage that a good practice guide would cover type testing.
Several members expressed agreement that there was a need for this guidance. Consideration would be given to proposing such a guide be included in the next NMS programme.
Chairman’s note: Following the meeting, reservations have been expressed about the need for such a guide. It has therefore been decided to put this issue on the agenda for discussion at the next IRMF meeting.
Review of Good Practice Guides
Vic Lewis (NPL) said that the current IRMF policy was to review GPGs within five years of publication. At present five GPGs had been published in the ionising radiation area, ranging from GPG 14 in March 1999 to GPG 49 in March 2003. Four of these involved IRMF directly, the fifth (GPG 34) had been produced by the nuclear industry and a sixth was being produced by the Air Monitoring Users Group.
There was some discussion on the meaning of the five-year deadline and it was agreed that the aim should be to review during the fourth year with the aim of bringing out a revised edition around the fifth year after publication. It was thought from the experience of feedback so far that no review would require as much effort as the initial drafting. In the meantime it was important that members did not wait until the fourth year to send in comments and corrections on any GPG. Comments should be sent to the Secretary and the Chairman of the working group, who in turn would pass them on to the appropriate experts to judge whether immediate corrections were required. For convenience, this would apply to all GPGs in the IR area.
If members felt that whole scale alterations and amendments were required, the review could be brought forward. NPL would appoint a chairman and secretary of the working group, after due consultation with IRMF members, and they in turn would appoint members to the working group. There should be a standing agenda item for discussion and review of the GPG situation. When the need to review a GPG was decided, this would be put in the minutes, posted on the IRMF website and an email would be sent to members as well.
There was a requirement to initiate review of GPG 14 during the next twelve months. The Chairman would consult with the Secretary on this matter.
NMS Programme Formulation
Martyn Sené (NPL) described the National Measurement System (NMS). Its purpose was to ensure that measurements in the UK were traceable to national standards, consistent and internationally recognised. Excellence in measurement was necessary for maintaining regulatory compliance, to improve quality of life and provide economic benefit. The NMS had several interlocking components. It maintained R&D in standards and measurements, the facilities necessary for this and for calibration purposes, and provided knowledge transfer with the user community. This was funded by the DTI with some co-funding from industry.
Martyn outlined the scope of the NMS programme in ionising radiation. This was one of the largest of the eighteen programmes in the NMS and supported many activities at NPL.
The NMS Programme was organised in three-year cycles, with the present one ending in September 2004. Programme formulation for the next cycle had already started with PA Consulting carrying out a consulting scoping study from April to June to determine the needs in the IR area. They were taking input from the user community, NPL, DTI, regulators and others.
There would be an orientation meeting at DTI on 24 June to discuss the report. The DTI would then hand over the process of programme formulation to NPL who would run a series of focus group meetings in September to which users would be invited. NPL would incorporate the findings into a draft programme for consideration by the advisory group (MACWG) appointed by DTI. A draft for public consultation would be put in the public domain in January 2004 for anyone to comment. IRMF members would be invited to comment by DTI. The programme would be finalised in April 2004 and would start in October 2004.
The purpose of this was to ensure that the NMS programme in the IR area was relevant to the user community. Members could help by commenting on the programme; they were invited to send comments to Nancy-Ann Hackmann and David Hatrick (PA Consulting) for the scoping study. Members were urged to come to the appropriate focus group meetings:
- radiation protection (12 September)
- environmental (16 September)
- medical applications (25 September)
- industrial dosimetry (planned via a meeting of the Panel on Gamma and Electron Irradiation).
Secretary’s note: the above dates have been announced since the IRMF meeting.
Members were also encouraged to comment on the public consultation document in 2004. A good level of interest and support was vital to shape the future work and to demonstrate to DTI that the work was of relevance.
Forthcoming Events
The following meetings and courses were announced:
- Workshop on Determination of Neutron Dose Equivalent, 29 October 2003 at NPL
(contact Peter Kolkowski, x6520) - Combined meeting of Gamma Spectrometer and Alpha Spectrometer Users Fora,
To be arranged in October/November 2003 at NPL (contact Simon Woods, x 6424) - Industrial Dosimetry Training Course, 4 November 2003 at NPL
(contact Peter Sharpe, x6647) - Practical Course in Reference Dosimetry, 26 - 28 January 2004 at NPL
(contact Rebecca Nutbrown x6473 or Lucy Sladen x6516) - History of Harwell, 4 June 2003, in Building 153, Harwell
British Nuclear Energy Society
The members had no further events to add.
Other Business
Clearance and Exemption Principles for the Nuclear Industry
Peter Burgess (UKAEA) drew members’ attention to a Nuclear Industry Code of Practice on Clearance and Exemption Principles, Processes and Practice. This was concerned with getting material off-site and the processes required for clearing areas of contamination. It had been produced by many of the principal users in the industry. He would push for this to be a generally available document.
Changing the cable?
Peter Burgess (UKAEA) commented that there had been a debate on whether it was possible to change the cable lengths to monitors without upsetting their calibration. Don Mackenzie was getting someone to investigate the influence of cable lengths. Geoff Druce (AWE) said that he would send Peter the results of work that had been done on this at Aldermaston. Several other members mentioned work they had carried out. Any data from other members sent to Peter would be gratefully received. He would report back to IRMF.
Next Meeting
The next meeting will take place on Wednesday 19 November 2003.
Secretary, IRMF
Centre for Acoustics and Ionising Radiation
National Physical Laboratory
Teddington
Middx TW11 0LW
The above report is a summary of the minutes of the meeting. The minutes have been sent to all members attending the meeting and to those who had previously expressed an interest in the activities of the IRMF.
Anyone with an interest in the metrology of ionising radiation who wishes to attend or learn more about IRMF meetings and activities should contact the Secretary.