THE DIMENSIONS

In maintenance and decommissionning many objects may have to be carried which have no longer anything to do with packages purposely built for transport of dangerous goods.

There are not intended for being transported, but they have to.

That is a somewhat specific and new situation, where the leading factors are no longer the compliance with the Regulations, but features which we have to deal with and to carry anyway.

The dimension is not taken in account in regulations however it has obviously a direct impact on total carried activity. The same surface specific does not obviously give the same dangerous character to a contaminated hammer or to the contaminated lid of a nuclear reactor.

We could quote here, the case of contaminated lids of nuclear reactors or the one of vapour generators : it would be very unprofitable and very prejudicial in term of exposure of the workers to decontaminate them near the reactor they come from.

Beside there could be in some extend an activation of these objects, even if it is often very difficult to tell the difference between activation and fixed contamination at least of the level of transport.

For such big objects Type A packages are already very difficult to design and manufacture, Type B packages which in certain cases would be Regulatory needed are almost impossible to conceive as far as the objects themselves present dimensions and weights which are at the limit of what is transportable.

In this context the use of Special Arrangement is difficult to avoid and the concept Transport System could in this case be developped in very useful manner.

CONCLUSION

There are many cases in the consideration of contamined objects, we tried to underline certain aspects of their multiplicity and complexity. There are certainly many other ones.

It seems that, this effort in accuracy made in Regulations SS6 1985 (amended in 1990) were certainly positive, but the implementation of these new Regulations show that many difficulties remain.

If the consideration of closed and unclosed surfaces and also fixed and non-fixed contamination is certainly a way to facilitate the classification of contaminated objects in transport, the limits of non contamination in the new Regulations entail many pratical difficulties, the thresholds are indeed rather low and it is sometimes difficult, time consuming and prejudicial from the exposure viewpoint to reach them.

A possible solution could be, when the total activity is low enough, that the criteria of classification be this total activity instead of the surface contamination only.

We have also considered the real problem of objects of which form and dimension do not adapt themselves very well to standardized packagings, even IP2. A regulatory way for carrying them should be preferable to the systematic use of special arrangements.

c\ TRANSPORT CATEGORIES FOR RADIOACTIVE WASTE E P GOLDFINCH

Nuclear Technology Publishing, Ashford, Kent,

United Kingdom Abstract

This paper reviews past and present regulatory requirements for the transport of waste materials in other than Type A and Type B packages It identifies three groups of materials analogous to Excepted packages, Type A packages and Type B packages into which the various waste forms can be fitted, so that they may be transported to the same levels of safety as their counterparts The paper makes proposals for materials which are intrinsically safe without packaging other than for administrative convenience and for wastes to be transported to the same levels of safety as Type A packages It is proposed that waste forms to be transported to the same level of safety as Type B packages cannot be prescribed in advance without the need for Competent Authority approval for each specific form or combination of waste form and packaging Finally it is proposed to revert to simple packaging requirements, equivalent to the earlier industrial and strong industrial packages The former have no quantitative performance requirements and the latter have requirements identical to Type A packages

1 INTRODUCTION

One of the most topical subjects under review within the IAEA Regulations for the Safe Transport of Radioactive Materials* ' is that of transport of low level radioactive waste A wide range of consultancy groups and technical committees have been or will be arranged by the Agency This Seminar should contribute very significantly to understanding the problems and their solutions, and, hopefully, assist in the current review and revision process for the regulations leading to the issue of the next edition around 1996 The author of this paper has been fortunate enough to have been involved with the development of thoughts and ideas, including participation in the two most recent consultancy groups and technical committee The ideas and proposals in this paper therefore reflect the input of many people at various stages of the development The author gratefully acknowledges the stimulus from discussions at the above meetings It is hoped that the final recommendations reflect the best of the ideas wherever they came from It is not practical to acknowledge ideas individually

2 HISTORY

Early editions of the regulations recognised the practical need to transport radioactive waste materials in packages other than Type A or Type B For such materials either the specific activity or the physical form or both give a degree of inherent safety not taken into account in the

factors limiting the contents in Type A packages or the leakage from Type B packages A number of fundamental radiological principles have been applied historically in developing the IAEA Regulations for the Safe Transport of Radioactive Materials Some have remained unchanged since the publication of the first edition in 1961 Others have matured or been adapted to meet changing international radiation protection recommendations A considerable degree of rationalisation of the justification of the radiological standards in the transport regulations has been introduced in recent years by the development of the Q system

1 1 1961 regulations

The 1961 regulations allowed shipments of unirradiated uranium 01 thorium ores and concentrates of these materials and residues from the processing of these materials to be exempted from the basic packaging and labelling requirements of the regulations, subject to exclusion of moisture, beryllium and pile grade graphite, and subject to quantitative radioactive contents limits in the vehicle, container or compartment It was required to be packed in strong, leak-proof packages or into vehicles or compartments thereof so that there would be no leakage during normal transport and no contamination of the conveyance, with loading and unloading under the direct supervision of the consignor or consignee Other low activity materials were allowed, with the same container, vehicle or compartment Limits as above, but without the necessity for strong industrial packages The consignor and consignee were responsible for the radiological control of the handlers At that time radionuclides were grouped into only three groups in the regulations and the contents in both Type A and Type B packages were limited to specified quantities for each of the three groups

1 2 1967 regulations

At the time of the 1967 regulations radionuclides were divided into seven groups Contents for Type A and Type B packages were still both limited quantitatively but higher activities were allowed as large radioactive sources with the packages having to withstand more hostile environmental insults The range of allowed low specific activity materials was extended to cover externally contaminated non-radioactive items and tritiated water Strong industrial packagings were required for the uranium and thorium materials, but liquids and gases were excluded Further relaxations were given for transport by exclusive use vehicles (then called Full Load)

13 1973 regulations

The 1973 regulations introduced the concept of A., and A-, values for individual radionuclides and applied these to the quantitative description of low specific activity materials The limit for low specific activity was basically 10 4 A2 per gram, essentially the same criteria being applied as for radionuclides listed as unlimited in the A2 table, in other words limited by the radiological consequences of inhaling no more that 10 mg of the material Non-radioactive contaminated items were still allowed In addition categories of low level solid materials were introduced These allowed for the transport of consolidated non-leachable materials at

-t».

specific activities 2Q times higher and non radioactive items contaminated to levels also 20 times higher, than for the corresponding low specific activity materials The accompanying advisory material drew attention to the fact that these latter contamination levels gave rise to surface dose rates of 20 Sv per hour and radiation levels of 7 Sv per hour at 30 cm The contamination had to be non-dispersible but no comment was made about its accessibility Of the seven categories of Low Specific Activity material

five could be carried in bulk as full load or alternatively in industrial packages and two in strong industrial packages The Low Level Solid materials had to be carried as Full Load in strong industrial packages I 4 1985 regulations

The 1985 Edition of the regulations and the amended version in 1990 introduced a reorganisation of the fundamental types of material into two groupings namely three categories of Low Specific Activity and two categories of Surface Contaminated Objects LSA-I was essentially the same as the earlier uranium/thorium categories but materials with unlimited A-, were included LSA-II limited materials to 10 Aj per gram with an arbitrary reduction factor of 10 for liquids Tritiated water up to 0 8 TBq per litre (20 Ci per litre) was included LSA-IH was relatively insoluble consolidated solid wastes with a specific activity 20 times higher than LSA-II This factor was a simple carry over from the Low Level Solid category of the 1973 regulations The two Surface Contaminated Object categories derived directly from one each of the LSA and LLS categories of the earlier regulations However subdivisions allowed for various combinations pf loose and fixed contamination in accessible and non-accessible locations The origin of the levels of contamination, namely the risk from high radiation levels at or near the surfaces, was ignored Interpretation of these requirements has been somewhat difficult The greatest complication introduced was that of three types of industrial packagings, namely IP-I, IP-II and IP-Ill, the first corresponding roughly to the earlier industrial packages, the second to strong industrial packages and the third to Type A However the distinction between IP-II and IP-Ill was minimal Allocation of each of the waste categories to a packaging type appears to have been somewhat pragmatic and complicated by arbitrary relaxations for the exclusive use of conveyances Conveyance activity limits were set dependent upon the type of material and its combustibility Radiation level limits on the unshielded contents were introduced to take account of the consequences of accidents leading to loss of shielding

1 5 Regulations review process

In the deliberations on the suggested amendments to the 1985 regulations, leading to the amended version in 1990, certain suggestions were regarded as major changes and could not be dealt with within the revision process until the major review, now in process, which will give rise to the 1996 edition, in other words the ten yearly review The problems identified related to the pragmatic factors embodied in the relationships between material types and corresponding packaging requirements, the use of freight containers as packagings and the inbuilt requirement to limit contents from an external radiation point of view on the basis of the dose rate from the unshielded contents This did not allow

designers to incorporate shielding which could be shown to withstand the most severe accidents without impairment

2 UNDERLYING PRINCIPLES WITHIN THE REGULATIONS

The regulations embody two main principles Firstly all limitations where relevant, are now cast in terms of AI and AZ Idealistically these parameters may be considered as yardsticks of risk for each radionuclide for external and internal dose routes, respectively This may seem a little simplistic but it is not far from true, at least for pure radionuclides Secondly, and historically, packagings and transport controls relate to three perceived levels of hazard, namely those arising from routine transport operations those arising from the incidents likely under normal conditions of transport and those arising following severe accidents Acceptable radiological consequences are related to packagings required to withstand each type of situation, respectively These can be considered as three groupings, one required to withstand only routine conditions of transport, one required to withstand incidents associated with normal conditions of transport and one required to withstand severe accidents These will be referred to hereinafter as Group I, Group II and Group III However, as an over-riding feature the radiological consequences of severe accidents must be able to be shown to be acceptable whatever group the material being transported falls into

2 1 Q system

The foundation to the current regulations, the Q system, limits contents in Type A packages (Group II) by modelling radiological consequences following severe accidents, to a limiting dose of no more than 50 mSv These packages must be shown to give rise to quite minimal radiological consequences following exposure to the conditions relevant to the respective Group, and so the requirements are quite restrictive, namely no loss of contents and only a small increase in the external dose rate The A-, values are used in quantifying the allowable leakage from Type B packages (Group III) , following tests to simulate the effects of very severe accidents The limiting consequences are again set at 50 mSv At the other end of the scale we have Excepted Packages (Group I) , for which contents are much more severely limited than for Type A packages At this stage in the development of the regulations, the radiological modelling leading to contents control and dose control is not consistent for Excepted Packages and materials (Group I) and control is exercised by factors which have a significant degree of pragmatism. The basic content limit for Group I is 10"3 of that for Type A (Group II) but because of the assumptions as to the behaviour of Excepted Packages, which are assumed to be completely destroyed and the whole of the contents dispersed, the accepted external dose is 0 05 mSv, whereas the accepted internal dose is SO mSv

3 CATEGORISATION OF WASTE MATERIALS

In this paper the underlying logic of three Groups of materials is carried over to waste materials Proposals are developed for the radiological modelling for materials divided into the three groups, as

above However, as a consequence, the lack of logxc in Group I referred to above will be exposed It would make sense, but is not the purpose of this paper, to revisit the requirements for Excepted Packages and materials, in order to unify the radiological logic throughout the regulations Suffice it to say that it is immediately obvious that some established levels could be increased and some could be decreased History has shown, though, that there is always significant reluctance to either increase or decrease levels which have been seen to be sacrosanct for many years

3 1 Radiological modelling criteria

In each group of materials it is necessary to propose and defend acceptable radiological modelling criteria, consistent with the Q system models The basic proposals are

311 Group I (withstand routine conditions only)

Routine conditions occupational dose limited by package external dose rates the same as for the present excepted packages

Normal conditions 0 5 mSv Severe accident 50 mSv

312 Group II (withstand normal conditions of transport) Routine conditions - occupational dose limited by

package external dose rates the same as for the present Type A packages

Normal conditions occupational dose limited by package external dose rates the same as for the present Type A packages

Severe accident SO mSv 313 Group III (withstand severe accidents)

Routine conditions - occupational dose limited by package external dose rates the same as for the present Type B packages

Normal conditions

Severe accident

occupational dose limited by package external dose rates the same as for the present Type B packages

SO mSv

It is apparent that for severe accidents acceptable consequences are the same for all groups However, the severity of the incident which is regarded as an accident and would be allowed to cause these consequences is quite different For Group I, required to withstand virtually no insult, even an incident corresponding to normal conditions of transport may be expected to cause major or complete package failure The allowable internal dose consequences proposed here are reduced by a factor of 10 compared with those accepted for a major accident i e 5 mSv instead of 50 mSv, because of the high frequency of use of packages in this category

It can be argued that the total risk from transport operations is inversely proportional to the perceived risk in each category because the total risk is determined by multiplying the number ot movements by the radiological consequences The apparent risk from the transport of Excepted Packages is higher than that from Type A packages, which in turn is higher than that from Type B packages This is because the underlying assumption for Excepted Packages that the whole of the contents become dispersible compared with between 10 and 10 for Type A packages (Q system model) is pessimistic, except for severe accidents

3 2 Assumptions and requirements

It is now necessary to make assumptions or place requirements as to the behaviour of packages within the respective groups following incidents at the required level of severity, consistent with the Q system assumptions Thus it is assumed that for

Group I the entire shielding is lost, the entire contents are released and 10% of the contents become dispersible following an incident to simulate normal conditions of transport It is further assumed that the entire shielding is lost and the whole of the contents become dispersible following severe accidents Severe accidents, of course, include fires These minimal requirements are effectively the same as having no packaging and allow the potential for material to be unpackaged other than for administrative convenience

Group II assumptions are ready made in the case of Type A packages For waste materials it again should be assumed that shielding is lost after a severe accident, but that this should not be so following 'normal conditions' incidents. The properties of the materials will dictate the internal dose consequences However the Q system assumption of a limiting physical intake of 10 mg of the material (viz as used for unlimited A2

nuclides) can be well utilised

Group III requirements are ready made in the form of Type B package requirements, namely minimal loss of shielding following normal conditions incidents and shielding retention to limit the external dose rates following severe accidents For Type B packages leakage is limited to 10 A.J in a week but this is derived from an acceptable post accident dose of 50 mSv For Group III wastes the same post accident dose criteria are appropriate, although not necessarily applied as a leakage rate in the case of internal dose consideration

4 TYPES OF WASTE

Let us now consider the types of waste that can be fitted into each of the groups and consequently the requirements which must be placed on these wastes or the assumptions which may be made about their behaviour

Let us now consider the types of waste that can be fitted into each of the groups and consequently the requirements which must be placed on these wastes or the assumptions which may be made about their behaviour