Wednesday 24^th November 2004
National Physical Laboratory

Present:

Chairman:		Steven Judge,		National Physical Laboratory
Secretary:		Clare Lee,		National Physical Laboratory
		Nasser Baghini		Imperial College Reactor Centre
		John Bennett		DERA RPS
		Reg Bosley		RWE Nukem
		Derek Brazer		AWE
		Peter Burgess		UKAEA
		Nichola Chapman		Imperial College Reactor Centre
		Robin Crosse		Thermo Electron
		Bill Croydon		Thermo Electron
		Julian Dean		National Physical Laboratory
		Denise Delahunty		RRPPS, Birmingham
		Geoff Druce		AWE
		David Fairweather		Centronic Ltd
		David Gallacher		St Thomas’s Hospital
		Norman Heffernan		Radiation Protection Service
		Chris Hill		NRPB, Chilton
		Vic Lewis		National Physical Laboratory
		John Locke		Serco Assurance
		Desmond MacMahon		National Physical Laboratory
		Shaun Marriott		BAE Systems Ltd
		Roy Mooney		Northern Ireland Medical Physics Agency
		Rebecca Nutbrown		National Physical Laboratory
		Sharan Packer		Health and Safety Executive
		Martin Palmer		National Physical Laboratory
		Dan Pepler		Radiation Protection Service
		Emi Piuila-Afitu		National Physical Laboratory
		Max Pottinger		BNFL Instruments
		Dave Rayner		National Physical Laboratory
		Tony Richards		Consultant, Leeds
		Paul Rochowiak		BNFL Instruments
		Martyn Sené		National Physical Laboratory
		Jon Silvie		BAE Systems Ltd
		Keith Simmons		MoD Nucleonic Calibration QP Committee
		Dave Taylor		National Physical Laboratory
		Russell Trueman		DERA RPS
		Eddie Veater		UKAS
		Jon Wardle		AWE
		Eliot Williams		UKAEA
		Mike Woods		IRMC

 

28.1 Welcome

On behalf of NPL, Steven Judge welcomed members to the Twenty-Eighth Meeting of IRMF; the meeting would focus on nuclear decommissioning and clearance.

28.2 Apologies for absence

Apologies had been received from:

Western Case	GE Healthcare
	Ludovic Chevallerau	Serco Assurance
	Tim Dollery	Mainance International Ltd
	Andy Main	Johnson Controls
	Duncan McClure	NRPB, Chilton
	Jan McClure	NRPB, Chilton
	Robert Munro	UKAEA
	Mike Nettleton	Health and Safety Executive
	Mike Renouf	British Nuclear Group
	Joanne Shaw	NRPB, Leeds
	John Simpson	RWE NUKEM, Winfrith
	Graeme Taylor	National Physical Laboratory

 

28.3 Approval of Minutes of Twenty-Seventh Meeting, 24 May 2004

The Secretary reported that she had not received any comments on the minutes prior to the meeting. However, the Chairman had received the following amendment at the meeting:

• The second sentence of the second paragraph in 27.4 should read 'Max Pottinger (BNFL Instruments) added that this standard indicated no uncertainty on the conversion factor was needed for monoenergetic radiations, however the committee felt this was incorrect.'

The Secretary agreed to amend the minutes featured on the IRMF website. The Chairman approved the remainder of the minutes after it was agreed that they were an accurate record of the meeting.

28.4 Matters arising

The Chairman reported that the following actions from the last meeting had been completed:

• The minutes of 26th meeting had been amended and put on the website as agreed;
• Adding a bulletin board and members' area to the IRMF website had not been possible, this position might change in the future as NPL's server was upgraded. If members wished for messages to be circulated, they could be sent to the Secretary for distribution;
• Eddie Veater (UKAS) had written to UKAS labs regarding the compromise position in conversion factor uncertainties on calibration certificates; a copy of his letter had been attached to the minutes of the 26th meeting;
• The NCE2 committee had discussed uncertainties in conversion factors; a copy of Tony Richard's letter had also been attached to the minutes of the 26th meeting. The authors of GPG49 agreed to update the pdf version to reflect this.

Tony Richards (Leeds) reported that the IPEM had nominated David Gallacher (Guy's and St Thomas's Hospital) to liase with the IRMF on their behalf to organise a comparison of medical X-ray qualities. David informed the meeting that the IPEM Diagnostic Radiology Special Interest Group were expecting the IRMF to take the lead on the exercise and no funding would be available unless a proposal was made to the Scientific Committee. David said that mammographic, diagnostic, CT and exit beams from patients should be considered for inclusion in the exercise. Jon Wardle (AWE) requested that ISO 4037 narrow and wide series were also included. A working group comprising Tony, David, Denise Delahunty (RRPPS), Jon Wardle (AWE) and John Bennett (DRPS) was elected; NPL would also nominate a secretary for the group.

Secretary's note: the NPL contacts for this exercise are Rebecca Nutbrown (Rebecca.Nutbrown@npl.co.uk 020 8943 6473) and Bob Angliss (Robert.Angliss@npl.co.uk 020 8943 6223)

28.5 Surface Contamination Monitoring Comparison

Clare Lee (NPL) informed the meeting that the exercise had begun and approximately one third of the 13 participating organisations had already completed their measurements. Clare thanked RWE Nukem, Winfrith, for having submitted their results very quickly.

Clare reported that Sean Collins (NPL) would perform the initial analysis of results. The working group for the exercise would meet in February and March 2005 to address any discrepant results, prepare conclusions for the exercise and make recommendations for the future. The report of the exercise would be published in March 2005.

View Clare Lee's presentation (274kB pdf)

Denise Delahunty (RRPPS) asked if a specific source - detector distance was to be used for the measurements and if the uniformity of reference sources should be reported. Clare responded that the protocol requested a source - detector distance of 3 mm be employed and the uniformity of sources should be reported if the participant organisations had time to obtain the data before the end of the exercise.

28.6 Gamma Monitoring Comparison

Martin Palmer (NPL) reported that the next exercise would commence in Summer 2005. Members could register to participate at the meeting and they would receive the protocol for the exercise in the New Year.

Registration form for Fifth Gamma Monitoring Comparison (79kB pdf)

28.7 Review of Good Practice Guide 14

Clare Lee (NPL) informed the meeting that she had received only 3 sets of comments regarding GPG14. One had related purely to Electronic Personal Dosimeters (EPDs), one to Quantities and Units and the third covered a variety of topics including the Contiguous Portions Technique.

View Clare Lee's presentation (310kB pdf)

Following some discussion by the members present, it was decided that:

• EPDs should not be added to GPG14 and a new Guide should be written for them;
• The deadline for comments would be extended until Christmas 2004;
• The working group should meet in the New Year to undertake the review of GPG14; based on the comments received and the latest standards and guidance;
• The working group should report their conclusions to the next IRMF meeting;
• The pdf version of GPG14 would be updated, but the GPG would not be reprinted;
• NPL would approach the DTI to request funding for a Guide for EPDs and to review the Contiguous Portions technique.

Clare asked members to publicise the review to colleagues and to submit their own suggestions.

28.8 Update on Nuclear Industry Code of Practice

Peter Burgess (UKAEA) updated the meeting on progress with the new code of practice 'Clearance and Exemption Principles, Processes and Practices for Use by the Nuclear Industry'. The code was aimed at project managers and intended to bring consistency within the industry to the characterisation of waste. Regulatory requirements, exemption orders, industry practices, clearance and sentencing processes, statistical sampling, measurement techniques, management principles, health, safety and environmental considerations and quality assurance were all covered. Flow charts had been included to guide readers through a variety of typical scenarios.

Peter said the Regualtors had commented favourably on the code and it was hoped that it would become a national reference document.

View Peter Burgess' presentation (24kB pdf)

Steven Judge (NPL) asked if there would still be a need for a more detailed document containing specific information on how the measurements should be made. Peter responded that more details would always be welcome, he felt that GPG30 could be developed further to incorporate a chapter for this.

Russell Trueman (DRPS) raised the issue of detecting natural Uranium on 'dirty' surfaces. Peter advised that surfaces to be monitored must be very clean but one should also carefully check the decay scheme of the radionuclide of interest to see if there are other emissions that would be easier to detect than a particles. The discussion continued to include radionuclides that may or may not have reached equilibrium with their daughter radionuclides, Jon Wardle (AWE) said that surface contamination monitoring alone was insufficient in these cases and HPGe or NaI detectors should also be used. Geoff Druce (AWE) added that the measurement technique ultimately depends on the risk to the business of an incorrect determination of the waste

Peter agreed to provide a link to the UKAEA website once the code was published on it; the Secretary would distribute this to members.

28.9 A Survey of Requirements for Standards and Guidance for Radioactivity Measurements in Site Decommissioning

Julian Dean (NPL) reported that the International Atomic Energy Agency had estimated the magnitude of the global decommissioning liability to be $900 billion (US) over the next 50 years. The UK Nuclear Decommissioning Authority (NDA) had been established to oversee the management of the 'clean-up' of legacy sites; this had been estimated to cost £48 billion.

In response to enquiries from many other organisations, NPL had successfully proposed a Measurement Infrastructure project for decommissioning to the DTI. The first stage of this project had been a survey of the requirements of a number of large organisations in the field; Julian presented the results of that survey.

The main findings had been:

• Building materials were the most common matrix being analysed, however their composition varied greatly;
• Tritium was the most common radionuclide of interest, although fission and activation products were also significant;
• The activity range of standards required spanned the low and medium level categories;
• Non-destructive methods of testing were dominant;
• There was no clear consensus on the priority of reference standards required;
• Comparison exercises / proficiency tests would be very useful;
• A national need existed to document the knowledge of leaders in the industry before they retired.

NPL considered the next step to be a workshop to prioritise the reference materials, proficiency testing exercise or guidance to be produced.

View Julian Dean's presentation (399kB pdf)

Keith Simmons (MoD Nucleonic Calibration QP Committee) suggested that Julian invite the MoD to the workshop. Julian agreed to pass details of the workshop to the Secretary for distribution amongst IRMF members, once they had been finalised.

28.10 Any Other Business

(i) Vehicle Monitors

Peter Burgess (NRPB) outlined a number of incidents that had occurred due to the accidental melting of radioactive material in scrap metal. These had led the scrap and recycling communities to install vehicle monitors at their gates; these monitors formed a last line of defence and did not constitute part of the regular clearance monitoring process. The monitors were large plastic scintillators that traced the radioactive profile of a lorry as it passed through; if no radioactive material was present the count rate dropped due to the shielding of natural background radiation.

Peter proposed that these vehicle monitors could also be used to monitor building materials. Experience had shown they were able to detect a 60Co point source of 10 kBq if it was positioned towards the edges of the lorry. However, based on calculation of the dose rates involved, it would be possible for a source of GBq activity to be undetected if it was located in the centre of the load and shielded by other materials. For bulk contamination, the minimum detectable activity concentration could be as low as 0.1 Bq/g. The balance between the number of false positive and false negative detections had to be considered carefully along with whether or not the monitor will be manned.

View Peter Burgess' presentation (74kB pdf)

Geoff Druce (AWE) added that neutron detectors had also been developed for this application and that a large body of information could be found on the IAEA website.

www.iaea.org

(ii) Enhanced Technical Underpinning of Installed Radiological Instruments at AWE

Geoff Druce (AWE) reported that AWE had continued their review of radiological instrumentation; he had reported on their portable instrumentation in the 27th meeting. The installed monitors in service at AWE and their requirements for the future had since been reviewed. One of the considerations had been the 'serviceability' of the instruments: manufacturers had been unable to guarantee how long they would be able to continue support for instruments they no longer produced. AWE had found that despite some of their older instruments being obsolete, they were the most serviceable as they did not contain electronic chips. Geoff concluded that AWEs installed instrumentation was generally very good.

View Geoff Druce's presentation (75kB pdf)

Keith Simmons (MoD Nucleonic Calibration QP Committee) said that he negotiated guaranteed, fixed term service contracts with manufacturers to cover the anticipated lifetime of the instrument to minimise the risk of obsolescence.

(iii) Loss of Primary and Secondary Standards in the UK

Keith Simmons (MoD Nucleonic Calibration QP Committee) expressed his concerns over the future of calibration services for wide area reference sources in the UK, he felt it was not clear if the DTI were committed to continue funding primary photon emission standards. Jon Wardle (AWE) added that he had not yet received confirmation from the DTI of funding to maintain this service and could not guarantee its availability from the end of 2004. Steven Judge replied that the proposal to continue to fund photon emission standards had been passed by the peer-review committee (the 'MAC-WG') and was expected to be formally approved by Lord Sainsbury in the near future.

(iv) Limit of Detection and Sensitivity

Russell Trueman (DRPS) said that he would like to have some common format for the definition of limit of detection and sensitivity; he knew lots of data already existed. Steven Judge (NPL) said Simon Jerome (NPL) had written a review paper on this topic, he should be invited to give a presentation at the next meeting.

(v) Assessment of Mixed Emission Contamination

Steven Judge (NPL) said that he and Emi Piuila-Afitu (NPL) had embarked on a project to relate the calibration of a surface contamination monitor using reference sources of limited radionuclides to the mixed emissions of real contamination. Steven invited members to contact him if they wished to assist in this. David Gallacher (St Thomas's Hospital) expressed an interest in taking part in the project.

(vi) Format of IRMF meetings and Catalogue

The Chairman made a variety of suggestions for changes to the format of future IRMF meetings. The members decided:

• A free industrial exhibition during coffee and lunch would be of interest when linked to the theme of the meeting;
• There should be one exhibition per year;
• The number of exhibitors should be limited to four each time;
• Exhibitors would be allowed posters and a small table;
• Manufacturers should not be allowed to make oral presentations of their new products within the meeting;
• Technical posters of members' work would be an excellent addition to the meetings;
• Meetings should continue to be held at NPL (rather than in new locations);
• The catalogue is a useful facility and receives a significant amount of interest;
• Links to calibration providers' websites alone would be insufficient;
• The catalogue should continue on the IRMF website.

27.11 Forthcoming Events

The Chairman presented the following list of

forthcoming events (56kB pdf)

No other events were announced by the members

27.12 Next Meeting

Secretary's note: it was agreed during the meeting that the next IRMF meeting would take place on 11 May 2005, however, it has been necessary to change this.

The next meeting will be held on Wednesday 18 May 2005 in the Globe Room, Bushy House. As usual, the meeting will commence at 10.30 am, with coffee served from 10.00 am.

Clare Lee

IRMF Secretary

Quality of Life Division, NPL

ACTIONS

Secretary Amend minutes of 27th meeting.

GPG49 Authors Update GPG49 to reflect the latest situation regarding uncertainties in conversion factors for neutron and gamma radiations.

All Members Register for Gamma Monitoring Comparison if you wish to participate

GPG14 Review Working Group Meet in New Year to revise GPG14. Consider effects of uncertainties in pass/fail criteria.

All Members Submit comments on GPG14 and publicise its review to colleagues.

Chairman Approach the DTI to request funding for a Guide on EPD calibration and to review the Contiguous Portions technique.

Secretary Invite Simon Jerome to speak about Limit of Detection and Sensitivity at the next meeting.

John Simpson, Peter Burgess and Tony Richards Continue dialogue with the NCE2 committee regarding the use of and origin of uncertainties for conversion factors stated in ISO 4037.

Members representing calibration facilities Send additions and amendments for IRMF Catalogue to the Secretary.

All members Inform the Secretary of suggestions for presentations on technical topics for the next IRMF meeting before the end of April 2005.

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