Minutes of the 3rd Meeting of the NMS Airborne Radioactivity Monitoring Users' Group
NPL – 3 December 2003
| Attendees: | Steven Judge | NPL (Chairman) | |
| Andrea Woodman | NPL (Secretary) | ||
| John Bennett | DSTL | ||
| Derek Brazer | AWE | ||
| Peter Burgess | UKAEA | ||
| Rupert Cockerill | AWE | ||
| Stephen Collins | Amersham | ||
| Julian Dean | NPL | ||
| Dave Dear | BNFL | ||
| Mike Dolan | AWE | ||
| Philip Doyle | Amersham | ||
| James Forde-Johnston | Canberra Harwell | ||
| Ken Frost | Southern Scientific | ||
| Jean-Louis Gouronc | MGPI Instruments | ||
| Norman Green | NRPB | ||
| Mark Griffiths | Amersham | ||
| Derek Hammond | NRPB | ||
| Simon Jerome | NPL | ||
| Desmond MacMahon | NPL | ||
| Ian Mather | RCD Lockinge | ||
| Trevor Nicholls | Lab Impex Systems | ||
| Richard Paton | NEL | ||
| Hilary Phillips | NPL | ||
| Max Pottinger | BNFL Magnox | ||
| Mark Rainbird | AWE | ||
| Shaun Robarts | Amersham | ||
| Gareth Roberts | RWE Nukem | ||
| Dale Robinson | BNFL | ||
| David Ryden | Canberra Harwell | ||
| John Simpson | RWE Nukem | ||
| Anna Williams | Amersham | ||
| Eliot Williams | UKAEA |
1. Chairman’s Welcome, Previous Minutes and Actions Arising
1.1 Steven Judge welcomed members to the meeting and passed on the news about Simon Woods, the secretary of the 2002 meeting, who sadly died in October after a long illness.
1.2 Steven gave a presentation describing the formulation of the new 3 year NMSPU programme which is due to start at NPL in October 2004. Anyone wishing to comment on the proposals put forward should contact Steven (Steven.Judge@npl.co.uk; 020 8943 8582) by the end of January 2004.
1.3 Each member was asked to introduce him/herself and describe briefly the kind of work they do.
1.4 There were some corrections to be made to the minutes of the previous meeting:
Comment 2.1.3 to be removed
In 3.1.1 the nuclide Pu-241 is to be replaced with Pu-239
Comment 5.4 needs more clarity. Change to “If a 19mmdiameter reference source is used the change in detection efficiency must be considered”. Action 3.1: Andrea Woodman to make corrections
1.5 Previous Actions
Action A2.1: Documents/references regarding self absorption. This still stands, any information to be sent to Andrea Woodman (Action 3.2).
Action A2.2: Speaker from NEL on flow rate measurements. Presentation given at meeting.
Action A2.3: Radon/thoron compensation techniques. This issue discussed at meeting in Any Other Business section.
2. Invited talk: “Self Absorption” – Mark Rainbird, AWE
2.1 Mark gave a very informative talk on the way AWE account for self absorption in filters. He explained the differences between the P factor, self absorption factor and transmission factor.
2.2 AWE estimate the amount of self absorption by the use of a light transmission box i.e. light absorbance is proportional to the depth of dust on the filter. They have also looked at spectral degradation due to dust build-up.
2.3 A table of the self absorption factors applied by AWE in various circumstances was displayed. Their data comes from studying a large number of air monitoring facilities with varying degrees of air filtering applied.
2.4 A comment was made following the presentation that spectral resolution can actually be increased by the presence of dust when carrying out continuous monitoring. Mark replied that the AWE studies were aimed at post event analysis techniques where the dust build-up occurs after the activity has been collected.
2.5 Comparisons had been made with radiochemical analysis at AWE and were in agreement.
2.6 It was generally agreed that this is a difficult subject and that there is no universal P factor.
3. Invited talk: “Flow Measurement” – Richard Paton, NEL
3.1 Richard described the work carried out at NEL which is a laboratory specialising in mechanical engineering. They are the custodians of the UK national standards for flow and density measurement.
3.2 He went on to talk about the factors which need to be considered when measuring flow and described the different ways it can be measured.
3.3 NEL operates the Flow programme within the NMS and they are in the process of formulating their new programme of work so Richard invited anyone with suggestions of projects they could consider to get in touch.
3.4 Following the presentation, members were interested to know about the reliability of mass flow meters and whether Richard had any information on a new type of shrouded sampling probe. Richard said he wouldn’t like to recommend any particular type but they are talking to the manufacturers of mass flow meters. It was considered that it would be useful to have a speaker on the new instrument at the next meeting (Action 3.3).
4. Update on Good Practice Guide, Max Pottinger, BNFL
4.1 Max gave an overview of what is being covered in the Good Practice Guide on the monitoring of airborne radioactive particulates in the workplace.
4.2 He presented a revised timetable for completion of the document as the work involved has proved to be more complex than first thought. It is now likely to be distributed for public consultation in November 2004 and published in 2005.
4.3 Max also proposed that a subgroup be formed to tackle the topic of self absorption. Peter Burgess, David Ryden, John Simpson and a representative to be decided from AWE volunteered to form this group. (Action 3.4).
4.4 A comment was made that it would be useful if Mike Dolan of AWE could collate some information regarding their measurements of Po210 to go onto the website (Action 3.5).
5. Any Other Business
5.1 A discussion concerning the accuracy of detection efficiencies for calibration sources followed. Over the years these sources have been made in two different ways, the rolled foil method or the anodised foil method. For detectors which subtend a small solid angle the detection efficiency is higher for the rolled foil sources by a factor of 2 or more. The problem is that users are not always aware of this or indeed which type of sources they are using and so a significant underestimation of airborne radioactivity is highly possible. It was suggested that the manufacturers be contacted to give some technical advice on this matter. This topic is to be highlighted in the GPG and it was suggested that it go into the next IR newsletter to raise awareness.
Action 3.6: Steven Judge to contact source manufacturers.
Action 3.7 Steven Judge to arrange for item to go into IR newsletter.
5.2 Questionnaire Feedback, Andrea Woodman
Andrea gave a brief presentation summarising the responses given in the questionnaires which were handed out to members at the meeting in 2002.
5.2.1 It was generally considered a good idea to set up a register of facilities on the webpage and also an e-mail discussion group. Action 3.8: Andrea Woodman is to organise these before the next meeting.
5.2.2 Filter media seemed to be a problem area and it would be useful to have a speaker at a future meeting. Action 3.9: Members to suggest filter media expert to approach.
5.2.3 It was unclear whether uncertainties were considered a problem so members should let Andrea know if they want this as a topic for discussion at a future meeting (Action 3.10)
5.2.4 There were plenty of ideas for further good practice guides. The next one is likely to be concerned with tritium monitoring.
5.2.5 It was suggested that a FAQ section be put on the website, if anyone is willing to write this they should send it to Andrea who will arrange for it to go on the webpage (Action 3.11).
5.2.6 RadNet was mentioned. Tom Nobes described this at the meeting in 2002 and there is further information on the Los Alamos website at http://www.lanl.gov/partnerships/rd100/summaries/98_execsum.html#radnet
5.2.7 There was a suggestion that a link to draft standards go on the website. Action 3.12: Andrea Woodman to arrange for the link.
5.3.1 Andrea Woodman presented information on draft standards being prepared by the NCE2 committee on behalf of the committee’s chairman Clive Dray.
5.3.2 Anyone wishing to comment on the standards or wishing to join the committee should contact Clive (clive.dray@btinternet.com)
5.3.3 Some of the members at the meeting were already involved in these standards and remarked that you really have to attend the committee meetings if you want to have your say.
5.3.4 Max Pottinger mentioned a new standard on particulate in air monitoring currently in progress which is open to comments. He wants it to be accepted in the UK though before it is made an international standard. The GPG is likely to be delayed because of this.
5.4 Action 2.3 of the previous meeting (Max Pottinger to supply Steven Judge with case for developing expertise in Radon/Thoron compensation) was discussed. The conclusion drawn was that there is no current need for developing new measurement facilities in the UK as NRPB can do this to some extent and a lab in Saclay, France has the capabilities. It was however thought that there is a requirement for a technical report explaining the methods and giving advice on radon/thoron compensation in order to maintain understanding in the UK although there could be some commercial aspect to this.
5.5 The next meeting is likely to held in November 2004. Members will be told of the date as soon as it is decided and invitations will be sent out nearer to the time. The possibility of having more than one meeting per year was discussed but it was decided that with the proposed set up of an e-mail discussion group and an improvement in the website we should continue with annual meetings.
6. Actions arising from the meeting
A3.1 Andrea Woodman to correct minutes of 2nd meeting.
A3.2 Anybody with information regarding self absorption factors to send them to Andrea Woodman.
A3.3 Andrea Woodman to arrange for speaker on shrouded sampling probes at next meeting.
A3.4 Peter Burgess, David Ryden and John Simpson to set up subgroup on self absorption factors for GPG along with a representative from AWE.
A3.5 Mike Dolan to provide information on Pu210 measurements for website.
A3.6 Steven Judge to contact source manufacturers for a statement on the construction of reference sources for calibrating “card” monitors.
A3.7 Steven Judge to arrange for the issues with reference source construction to be highlighted in next IR newsletter.
A3.8 Andrea Woodman to organise register of facilities and e-mail discussion group.
A3.9 Members to suggest expert on filter media for Andrea Woodman to invite to future meeting.
A3.10 Members wishing to discuss uncertainties, or any other topic at a future meeting should let Andrea Woodman know.
A3.11 Any member willing to write a FAQ section for website to send it to Andrea Woodman.
A3.12 Andrea Woodman to arrange for a link to draft standards to go onto the website.
Andrea Woodman
Secretary, ARMUG
12th January 2004