Cavendish Conference Centre, London, 27 February 1996
Exemption and clearance levels is a phrase that seems to have become ingrained on my mind of late, such is the growing interest in the subject. The more one thinks about it, the more issues and concerns there seem to be, and what it sometimes seems could once have been solved over a cup of coffee and half a side of A4 now involves many different organisations, groups and interests (local, national and international). The subject is an important one that has significant implications for all of us and, for this reason, SRP undertook to arrange a workshop. The intention was for representatives of all of the interested parties to exchange information on current developments in the area, and identify priority issues and implications.
John Croft (NRPB) had volunteered to act as Chairman, and opened the workshop by noting that although the subject covered some sensitive areas, he hoped the event would have an informal nature where issues could be aired and the participants could learn from each other. John noted that the day was split into two sessions. The morning session was centred on the problems and challenges faced by users, whilst the afternoon was given over to discussion of the way forward in the light of recent Directives, Government statements and developing international guidance.
Starting the morning session, Tony Richards (University of Leeds) noted that the most useful exemption level for Research, Teaching Establishments and Hospitals is that for Very Low Level Waste (VLLW), commonly called the `dustbin' limit. However, this presents some difficulties, primarily because of the need to find enough non-active refuse to meet the associated dilution requirements, which can make its use unrealistic for the volumes that need to be disposed of. In this case, the costs of alternative disposal can be significant and so these Establishments would welcome a more realistic system.
During the subsequent discussion, John Croft wondered whether the difficulties that were being experienced in using the VLLW order arose because waste was not being properly segregated at source. Tony agreed that this can be a problem, both in ensuring that segregation criteria had been applied correctly, and in finding the resources to actually do it. Also, there is a conflict because the desire to segregate waste to ensure control conflicts with the desire to dilute activities by dispersing wastes. The difficulties of using the VLLW exemption order were echoed by other delegates, primarily because of the seemingly perverse need for the highest level of QA for the lowest level of waste, which again makes disposal by this route expensive. For the regulatory community, John Hetherington (HMIPI) noted that although the VLLW figures may be reviewed, and there may be opportunity to relax the figures for certain nuclides, it was by no means certain that this would be the case generally, and some may need to be tightened.
Representing the hospital sector, Cathy Griffiths (Royal Hallamshire Hospital) commenced by summarising the changes to the Hospitals Exemption Order that would be welcome. Amongst other things, this now requires waste to be accumulated for a maximum period of only two weeks, which in turn means that partially filled containers are being sent for incineration at premium prices. There are no provisions covering gaseous waste disposal, even though this may be a discharge route from, for example, patients undergoing 14C breath tests, and the draft revised Euratom Basic Safety Standards gives a total activity for exemption (from reporting and authorisation) for 14C of 107 Bq. Similarly, and as for other sectors, there is no liquid equivalent to the 0.4 Bq g-1 exemption level for solids that was incorporated within RSA60 even though, again, there are potential discharge routes. Referring to the proposed BSS Annex 1 figures, Cathy welcomed the potential flexibility, but noted that the proposed limits for nuclides such as 133Xe were much more restrictive than those for other commonly used nuclides. Keith White (West Middlesex University Hospital) put forward the view, supported by many present, that directing so much resources at such trivial levels of activity did not make sense when compared against the real issues of life and death present in this sector. In summary, Cathy made a plea for a review of the method used to determine exemption levels so that these were logical, consistent and realistic and perhaps based on Annual Limits of Intakes, or some other rational basis.
Representing the industrial sector (excluding the Nuclear Industry), Ciaran McDonnell (NRPB) noted, as may be expected, that commercial considerations are the primary decision drivers for users. Concern mainly focuses on the need to avoid liabilities that could interfere with future uses (and hence saleability) of the site such as any need to register the site. For this reason, small users often approach such situations simply by disposing of any item that is even mildly contaminated (rather than attempting decontamination) using, for example, the VLLW or Phosphatic Substances Exemption Order (for contaminated soil from luminising sites). This may involve dumping significant amounts of material such as soil, concrete and so on which, whilst no significant problems are encountered, may not utilise resources effectively.
In terms of the way forward, Ciaran noted that any changes to the two most relevant EOs (Exemption Orders) mentioned above may create problems for industrial users. Also, guidance on whether RSA93 applies to contaminated land as well as `waste' would be welcome. What was to become a recurring theme - the question of whether the current exemption levels are set at the right levels, or whether they are appropriate to all situations including, for example, the possible re-use of land from industrial sites for other activities or housing projects was also raised.
The last user representative of the day was Graeme Stonell (UKAEA), who represented the nuclear industry. Graeme started by highlighting the usefulness of the Exemption Orders, and in particular the Substances of Low Activity Order, which is very useful, but again makes no provision for liquid wastes and is not nuclide specific which would be a worthwhile change. If the EOs are to be reviewed or replaced, then the result should ideally be based on genuine hazard and also needs to be practicable. This latter point had been made in one form or another all morning - exemption levels as currently set are at or near the capability of detection, which in turn means that waste often has to be sent via costly disposal routes simply because the very low activity contents cannot be measured.
The current constraints on recycling and re-use follow on naturally from this. Reflecting the views given by Ciaran McDonnell, industry would like to be able to recycle materials, rather than dispose of them, but requirements in this area are not clear or consistent. Views and guidance are starting to emerge, but any system needs to be sufficiently realistic to allow re-use rather than force disposal, which again comes back to a need to use realistic models that reflect the practicalities of real life.
As with the industrial sector, the issues pertaining to the re-use of land present an increasingly pressing problem for the industry. The problems are, in general terms, very similar to those being experienced by other sectors - for example, what criteria are appropriate for assessing land, and how can this be done at reasonable cost. Over and above these, however, is the need for NII to be satisfied that there would be no danger from ionising radiations as a result of a site being delicensed. In summary, all of these questions impact heavily on the industry, and considerations that seem simple in themselves, such as the modelling criteria used to determine clearance or exemption levels, can have far-reaching effects. To avoid this, Graeme ended with an overall plea for end-users to be consulted during the formation of figures and policy, rather than after these have been developed.
Ending the morning session, Joe McHugh (HMIP) noted that Regulators have to remain impartial whilst ensuring, so far as possible, that users choose disposal methods which conserve the capacity of national facilities such as Drigg (although one delegate noted the potential for conflict in these aims). Joe suggested that regulators welcome being involved in discussion about clearance and exemption issues for individual projects at an early stage, and try, for example, to ensure that future uses of sites or cleared materials do not pose unacceptable risks. Referring to the earlier comments on methods of compliance with exemption levels, he said that the best way of dealing with this was to discuss it with the relevant Inspector. Finally, he suggested that there may be tendency to classify wastes from active areas as active even when they are not, and there may therefore be some benefit in trying to avoid this.
The afternoon session was given over to Government and NRPB to describe how the system might develop and address some of the difficulties identified. John Cooper (NRPB) started by summarising references to exemption within ICRP60, the draft revision of the Euratom BSS and the IAEA BSS. Numeric criteria for exemption levels had previously been developed by IAEA/NEA with the aim of ensuring that radiological protection, including the cost of regulatory control, was optimised. These criteria were an annual individual dose of no more than 10 µSv from each exempt practice and a collective dose commitment from one year of unregulated practice of no more than 1 man Sv. Models were then developed to reflect a range of scenarios, and in doing so it was identified that there was a need to have an additional criterion, namely that skin doses did not exceed 50 mSv y-1. The aim was to develop a system whereby small users (such as hospitals) could be exempt from reporting and authorisation where appropriate.
John briefly summarised the variety of work currently going on to formulate suitable proposals for clearance regimes, but noted that all of the groups involved agree that clearance levels must be set at levels less than or equal to exemption levels. These too were based on an assumption that 10 µSv per year could be taken to be a trivial individual dose level. Roger Coates (BNFL) questioned the blanket application of this dose level, and suggested that at these levels, a few tens of µSv would be a better interpretation that would allow flexibility, and in any event there should be a different (higher) level should be applied to workers. Echoing the morning speakers, Roger made a plea for end-users to have the opportunity to review the models that were being developed to set exemption and clearance levels. John Croft wondered, as a final point on this particular subject, whether the system used to develop the models places too much emphasis on the use of conservative parameters at each stage, and therefore ends up making the system too restrictive.
Robert Jackson (Department of the Environment) then spoke about the regulatory implications of the Euratom BSS Directive and the recent White Paper on Waste Management. Summarising the current UK regulatory position, Robert noted that users must notify HSE of the intention to work with radioactive material and register or obtain authorisation from HMIP under RSA93. It is worthy of note that these two requirements are for fundamentally different purposes - the first is essentially to aid protection of workers, whilst the second is aimed at the regulation of waste management. Exemptions from both of these requirements are possible, the first through, for example, schedule 2 of the IRRs and the second via the exemption levels specified for certain naturally occurring radionuclides in Schedule 1 of RSA93 and the RSA Exemption Orders. Studies of the RSA EOs had indicated that whilst they are useful (for example by allowing material to be cleared from sites using the VLLW EO), and their use results in negligible exposures, there is little consistency either in strategy or derivation.
Turning to the draft BSS Directive, Robert described the system contained within that Directive. This is broadly similar to the current system, i.e. it requires notification and authorisation for a number of specified operations as well as other cases where the exemption levels given in Annex 1 are exceeded. However, a specific article covers the authorisation needed for the disposal, recycling and re-use of active materials from practices that themselves require authorisation. The key point here is that this requirement may be waived if clearance levels established by the national Competent Authorities are complied with (such levels must, however, follow the general criteria used to determine the Annex 1 figures). The Directive also makes provision for the protection of workers from enhanced levels of natural radiation, although again with some possibility for exemption. In summary, Robert noted that the Directive had ended up framed in a manner that would allow the current UK system to be maintained, although the precise manner of implementation, and hence its effects, had yet to be determined. Nevertheless, DOE intends to carry out a review of the RSA EOs including their derivation and although the overall intention is to minimise the regulatory burden, there may well be winners and losers.
Ending the afternoon session, Mick Bacon (Health and Safety Executive) started off a debate on the means and criteria by which nuclear sites can be delicensed. As noted earlier, HSE have a responsibility to be satisfied that there is no danger from ionising radiations before a site can be delicensed, and there is currently no formal consensus on exactly what this term means in practice. Until this is formalised, applications for delicensing are being dealt with on a case by case basis, with the responsibility being put on site management to show that this condition has been met. Many delegates suggested that HSE should be able to base decisions on their Tolerability of Risk (ToR) philosophy. Iain Devine (Magnox Electric), supported by a number of other attendees, noted that a return to a `greenfield' site may not necessarily be the best option for `UK plc' and that there may, perhaps, be other options open, such as conditional delicensing for specific activities.
The day seemed useful to all of those who attended. Obviously, no firm conclusions had been reached, but the problems and difficulties faced by users had been aired, and it was interesting to note the common threads that affected all of the sectors using radioactive materials. These essentially consisted of the problems experienced as a result of increasingly trivial and sometimes unrealistic figures being set as exemption or clearance levels which, together with the associated difficulties in monitoring, sometimes drive the user to dispose of material inappropriately at significant expense. The widespread uses of the RSA Exemption Orders were described and finally the growing need for clear and consistent criteria on how to delicense sites was highlighted. The Regulators gave useful summaries of how the criteria had been developed, and how they might develop in future. I am sure they were interested to listen to the real problems being experienced, and will be able to feed this knowledge into future consideration of the subject.
I think all of us at the workshop were aware that a great many people have a strong interest in this subject, and that many more would have attended the workshop if places had been available. I am conscious of the heavy burden on me to report on the workshop in a manner that suitably captures the major points of the day. Many ideas and thoughts were put forward, and a full summary would probably take up the whole of this journal - nevertheless I hope that I have managed to capture the gist of the meeting. I would like to thank all of those who were involved, and in particular the speakers, John Croft and SRP generally for what proved to be a good day.
Perhaps it is appropriate to end on a thought put forward by Roger Coates that echoes my comments in the opening paragraph. Roger has a dream - supported by many I'm sure - that over the next few years we can end up with a system that has a single set of numbers for unconditional clearance and exemption that are technically reasonable. These would be based on the BSS Annex 1 values, have 1 Bq g-1 as a minimum value and be consistent with surface contamination levels of 0.4 Bq cm-2 α/ 4 Bq cm-2 β which are currently in widespread use, both in the UK and the rest of the world. Perhaps there may be higher levels for conditional clearances, but it's a good target to aim for during the revision of guidance and legislation that is planned. Wouldn't life be nice...
D K Owen
