REGULATORY ASPECTS OF THE TRANSPORT OF IRRADIATING AND ALPHA WASTE IN FRANCE

C DEVILLERS, M. GRENIER, J. LOMBARD, F MATHIEU Institut de protection et de sûreté nucléaire,

Commissariat à l'énergie atomique, Fontenay-aux-Roses, France Abstract

The introduction of the 10 mSv/h at 3 m limit for LSA unshielded material makes impossible the transport as LSA matenal of the most irradiating wastes from EdF PWR's operations At the present time, the concerned EdF's waste blocks are allowed to be transported as LSA III material under special arrangement A new package design, equivalent to a type B package, will be available for their transport before the end of the year 1995 It consists in a reusable steel cylinder over packing each block Compliance of this package model with transport safety requirements will be demonstrated by taking into account the non dispersability, as LSA III

material, of the irradiating waste

The transport of LSA combustible material is affected in the revised regulation by the new limitation to 100 A2 of the total activity per conveyance Complying with this limit would strongly reduce the quantity transported by conveyance and therefore multiply the number of journeys, which is not desirable A two step approach has been accepted by the French Competent Authority for the transport of these waste a) A specific ISO 20' container, thermally insulated, can be used under special arrangement for the transport of LSA combustible matenal having a total activity per conveyance higher than 100 A2 Furthermore additional safety measures have to be implemented for these transports

b) After the end of the year 1995, a type B package must be used for activity contents per conveyance higher than 100 A2 A specific 20' ISO container, complying with type B requirements, is being developed for that purpose The total plutonium mass transported per conveyance will be limited to 400 g for cnticahty and physical protection considerations

An interpretation of the general LSA requirements formulated in the current IAEA Regulations is presented with respect to the homogeneity of the radioactive matenal, and the definition of the unshielded material

1) INTRODUCTION

The aim of this paper is to present the regulatory aspects or consequences of recent developments concerning the transport of low and intermediate wastes in France They are mainly due to the impact on LSA material transport activities of the revision of the French Regulation for the transport of dangerous goods [1], according to the IAEA Regulations for the Safe Transport of Radioactive Material [2], 1985,1988 and 1990 editions

2) IRRADIATING WASTE

Safety Series n°6 [2] indicates in its § 422 that the quantity of LSA material in a single industrial package shall be so restricted that the external radiation level at 3 m from the unshielded matenal or object or collection of objects does not exceed 10 mSv/h

The introduction of this new limit makes impossible the transport as LSA material of the most irradiating waste from EdF PWR's operation such as primary loop filters or ion-exchanger resins Therefore a type B package should be used

These wastes, conditioned in cement or polymer, correspond roughly to 5% of the total volume of waste sent by EdF to the Agence Nationale pour la gestion des Déchets RAdioactifs (ANDRA) waste disposal facility

At the present time, due to power plant operation and waste storage constraints on site, the existing EdF's waste blocks are allowed to be transported as LSA III material under special arrangement for a maximum total activity of 5 TBq, corresponding to a maximum dose rate up to 4 Sv/h at the surface of the unshielded matenal (or up to 100 mSv/h at 3 m from the unshielded matenal) Additional safety measures were required for these transports such as the choice of certified earner road transports (about 30% of these transports)

To cope with the technical requirements of the ANDRA waste disposal facility, in addition to leaching tests these blocks have been submitted to 1 2 m drop tests, as well as a 800°C, 30 minutes fire test These tests guarantee a good behaviour for leaching, fire and potential mechanical constraints For more severe accidental conditions, such as those envisaged by the IAEA Regulations for qualifying type B packages, the consequences of atmospheric dispersion are a priori limited due to the fact that the material is LSA Nevertheless, these tests are not sufficient to prove that the radiation shielding is adequate to withstand the IAEA type B tests Before the end of the year 1995, a new package design equivalent to a type B package, will be available for their transport It consists in a reusable steel cylinder over packing each block (see figure 1) It can be handled by the existing means at

Figure 1 : OVERPACK FO IRRADIATED WASTE

Ed F power plants and at the ANDRA waste disposal facility. It will ensure the biological protection in case of accidental situations considered for the qualification of type B packages.

Compliance of this package model with transport safety requirements will be demonstrated by taking into account the non dispersability, as ISA III material, of the irradiating waste. That is to say, the designer would not have to demonstrate compliance with regulatory release rate criteria both in normal and accidental situations. This exception would insure consistency with Safety Series n°6 requirements applying to packages used for the transport of non irradiating ISA wastes. Therefore attention will mainly be devoted to the compliance with external dose rate criteria after the type B tests (the 10 mSv/h at 1 m criterion).

3) ALPHA WASTE

The transport of combustible radioactive materials with low specific activity (LSA II or ISA III), in industrial packages, is affected in the 1985 issue of the IAEA recommendations [2] regarding the safety of radioactive material transport by a limitation at 100 A2 of the total activity per conveyance (road vehicle, rail car...). The transport of combustible surface contaminated objects (SCO) comes under the same limitation.

3.1 Problems raised bv the transport of non immobilised waste with alpha emitter low specific activity :

Solid waste containing small quantities of alpha emitters per mass unit may be put into the following categories (e. g. plutonium 239):

- LSA II, if their alpha emitter specific activity is less than 2.10'5 TBq/kg (0.5 Ci per ton),

- LSA III, if the alpha specific activity is less than 4.1 Q-4 TBq/kg (10 Ci per ton), provided that the requirements concerning leaching properties are met.

Accordingly, drums, blocks or boxes containing non immobilised waste with small amounts of alpha emitters per mass unit, arising essentially from CEA laboratories and likely to be accepted in surface waste disposal sites, may be put into the LSA II category, the upper limit of the specific activity for this category, corresponding roughly, after immobilisation at the waste disposal site, to the limit of 4.10-6 TBq/kg (0.1 Ci per ton) set for the alpha specific activity of waste packages being accepted in such sites. If the waste are considered as combustible, the limitation to 100 A2 of the total activity per conveyance would require a reduction of the mass of waste transported in the form of industrial packages (in the present case 20' or 40' containers) as low as one ton if the activity of all the waste were at the upper limit of the LSA II category. An accurate inventory of the total alpha activity to be shipped, and realistic estimates of the alpha emitters concentrations in the waste might attenuate the effect of this limitation. However, the limitation of the total activity per means of transport concerns the transport practices in shipments of Low Level Waste from CEA laboratories to surface waste disposal facilities.

The effect of limiting to 100 A2 the total activity per conveyance applicable to combustible wastes, is still more pronounced for drums, blocks or boxes of solid wastes which are not acceptable in surface waste disposal centres because of their excessive alpha emitter content, which have to be sent to interim storage sites, and which can be classified as LSA III. Indeed to be able to transport such wastes in the form of industrial packages, the mass of waste transported by conveyance would have to be reduced to a value between 50 and 1000 kg.

It should be pointed out that the classification as "non-combustible" material of solid non immobilised wastes transported in drums, blocks or boxes is delicate, as soon as the waste are put in an organic envelop. Most of contaminated non immobilised radioactive waste shall therefore be considered as "combustible".

On the other hand, it should be borne in mind that wastes made of well geometrically defined independent pieces, for instance those coming from the dismantling of nuclear installations, can be put into the category of surface contaminated objects (SCO). The limitation of the total activity to 100 A2 also applies to this category, whether the wastes are combustible or not, if industrial packages are to be used. It appears clearly that the intention of 1985 issue of the IAEA regulations is to prevent the transportation of too large amounts of LSA or SCO materials in industrial packages, not designed to withstand accident conditions, as soon as a subsequent fraction of the activity contained in the conveyance is likely to be dispersed in the event of an accident.

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OS This situation did not escape to the attention of the French transport safety authorities Well in advance of the issue of both international and national transport regulations, complementary safety measures were taken for this category of transportation both to prevent accident and to limit the consequences of a possible accident in particular as concerns the risk of fire In addition, each transport campaign is the subject of a specific safety examination and of inspection of the loading conditions

The entry into force of the 100 A2 conveyance limit has major practical repercussions

it could lead to subdividing the material into batches of activity less than 100 A2 and accordingly increasing the number of shipments, so that mdustnal packages may still be used (in which case, large containers could no longer be employed) , obviously, this solution is penalising on an economical level and the benefits as regards safety are low,

- or, what is more likely, it imposes a requirement to move directly from industrial packages (IP) to far stronger type B packages for which there is no limitation of the total activity transported , the number of transport to be carried out is an incitement to develop a large-size package, but at the cost of difficult technological problems

3 2 Envisaged solutions

A two step approach has been accepted by the French Competent Authority for the transport of these waste conditioned in 100 or 200 litres drums

a) A specific ISO 20' container, so-called DV77 (see figure 2), thermally insulated, can be used under special arrangement for the transport of LSA combustible material having a total activity per conveyance up to 600 A2 The maximum individual dose associated with the most severe accident involving this quantity is about 50 mSv, (see [3]), figure considered as acceptable This ISO 20' container can transport 60 drums of 200 litres or 150 drums of 100 litres

Furthermore additional safety measures have to be implemented for these transports such as escort car and speed limitation

b) For activity contents per conveyance higher than 100 A2, after the end of the year 1995, a type B package must be used A specific 20' ISO container so called TN GEMINI (see figure 3) complying with type B requirements is being developed for that purpose It will allow to carry transuranic waste in 40 drums of 200 litres or 60 drums of 100 litres , 5 m3 or 10 m3 metallic containers or fibber reinforced concrete cylinders may also be accommodated The total plutonium mass transported per conveyance will be limited to 400 g for cnticality and physical protection considerations

v/mna

Figure 2 THEDV77

4) INTERPRETATION OF THE LSA IAEA REQUIREMENTS

An interpretation of the general LSA requirements formulated in the current IAEA Regulations [2] has been made with respect to the homogeneity of the radioactive matenal, and the definition of the unshielded matenal

The applicants mentioned their difficulties in the interpretation of the new rules in this field [2], [4], [5]

A group of the French mam applicants was gathered under the aegis of IPSN Two main parameters were considered the massic specific activity and the distribution of the activity in the material Homogeneity is desirable in order to avoid the diversion of the low specific activity concept However the practice requires to

40 DRUMS 1200 IIÏREI

SMOCK ABSORBING COVER

CONTAINMENT WALL

Figure 3 : THE TN GEMINI

limit and define this homogeneity in a way as simple as possible. Therefore Safety Series n°37 [5] proposes a factor 10 in the LSA II case, 3 in the LSA III one, between the global average activity and that of each elementary volume. A fire for example involving only the most active part of non homogeneous waste would have by definition consequences of limited dimensions. On the contrary, a fire involving the whole material would bring us back to the average specific activity.

The elementary volumes were chosen essentially for practical reasons 0.2 m3 being the volume of the most frequent LSA drums, this figure was selected in the LSA II case by the group in accordance with Safety Series n°37 Half this volume was considered as reasonable for LSA III, supposed to be more homogeneously distributed.

Besides it seams logical that each isolated volume of 0.2 m3 having an average specific activity of 10~4 A2/g is supposed as acceptable as an inserted elementary one having an activity 10 times higher.

The proposed outcome is the following :

In order to verify the homogeneity of distribution of this activity in the material, the maximum volume of the wastes in the packaging is assessed and is divided m N

elementary volumes smaller than or equal to 0,2 m³ for LSA II material, smaller than or equal to 0,1 m3 for LSA III material

It is then verified that the specific activity contained in each of these elementary volumes is lower than 10"3 A2/g for LSA II material, lower than 6.10"3 A2/g for LSA III material.

Furthermore, the waste producers have to make sure that the activity is not gathered in one or a few of these elementary volumes. Every volume of waste smaller than 0,2 m3 for LSA II material (respectively 0,1 m3 for LSA III material) is considered as meeting the rules of homogeneity, when complying with specific activity conditions.

Furtermore, the assessment of the dose rate at 3 m from the surface of the material has to be made for the volume of the waste, without considering radiological protection.

5) CONCLUSION

The adaptation to the new rules of transport of radioactive waste was not obvious in France and it is still in development. But the target will be hit and the safety of these transport will be substantially improved.

REFERENCES

[1] "Règlement pour le transport des matières dangereuses par route (RTMD)".

Annexe à l'arrêté du 15 septembre 1992. JO du 13 octobre 1992, Paris.

[2] IAEA "Regulations for the Safe Transport of Radioactive Material".

1985 Edition (As Amended 1990), Safety Series n°6, Vienna 1990.

[3] J. Lombard, P. Appleton, H. Libon, H. Sannen, T. Schneider "Application of the Transport System Concept to the Transport of LSA Waste". IAEA Seminar on Developments in Radioactive Waste Transport, IAEA-SR-189/5, Vienna 21 -25. 02. 1994.

[4] IAEA "Explanatory Material for the IAEA Regulations for the Safe Transport of Radioactive Material". 1985 Edition (As Amended 1990), Safety Series n°7, Vienna 1990.

[5] IAEA "Advisory Material for the IAEA Regulations for the Safe Transport of Radioactive Material" 1985 Edition (As Amended 1990), Safety Series n°37, Vienna 1990.

-Joo REGULATORY ASPECTS IN THE TRANSPORT AND DISPOSAL OF LOW AND INTERMEDIATE LEVEL

RADIOACTIVE WASTES FROM FUEL CYCLE OPERATIONS