Nuclear Engineering and Design 176 (1997) 177–180

Technical note

Characterization and acceptance criteria of conditionedradioactive wastes at El Cabril disposal facility

Antonio MoralesENRESA, Waste Producers Relation, Emilio Vargas 7, 28043, Madrid, Spain

Abstract

El Cabril Disposal Facility is in its 4th year of operation. In October 1996 a new extension of the operationallicence will be required. In order to obtain that, a revision of the safety study has been recently sent to the Spanishregulatory body. The characterization and acceptance criteria of the conditioned wastes is a significant part of thesafety study, meaning that the limits given in this paper are actually under study by the Spanish Regulatory Council.The paper includes� Classification of wastes packages� Acceptance criteria

1. related to safety objectives;2. related to quality objectives;

� Quality controls associated to the acceptance process.© 1997 Published by Elsevier Science S.A.

1. Introduction

All solid or solidified wastes which are incorpo-rated in an approved container, thus forming adisposal unit (DU), must first undergo a processof acceptance and associated testing ensuringcompliance with the two basic premises adoptedat the facility in relation to wastes:

—identification;—due conditioning in the DUs.The accep-

tance methodology used depends on classificationof the wastes, which in turn depends on produc-tion conditions (typified or non-typified wastepackages) and on the properties required for the

level of activity of the wastes following theirconditioning (levels 1, 2 and 3).

2. Waste package classification by productionconditions; acceptance methodologies

Waste packages are classified as being typifiedor non-typified, depending on the conditions un-der which they are produced.

Typified waste packages are those produced inaccordance with a descriptive document drawn upby the producer in question and approved byENRESA; this document is known as the packagedescription document DOB.

0029-5493/97/$17.00 © 1997 Published by Elsevier Science S.A. All rights reserved.

PII S0029 -5493 (96 )01352 -0

A. Morales / Nuclear Engineering and Design 176 (1997) 177–180178

Non-typified waste packages are those whichhave not been produced in accordance with a dulyapproved DDB, as a result of either their havingbeen produced prior to the implementation of thismethodology or events having arisen as a result ofnon-scheduled operational situations. In the fu-ture, all reasonable means will be deployed inorder to minimize the inventory of non-typifiedwaste packages.

The acceptance methodology used for typifiedwaste packages is based on the drawing up andapproval of a generic document known as theprocess book and on the application, byENRESA, of periodic documentary controls (pro-duction controls) and testing of representativepackages (supercontrols).

Acceptance of non-typified waste packages isbased on a closed document (applicable to a giveninventory of packages) known as the acceptancedossier and on verification tests.

3. Waste packages by level of activity

Wastes are classified by their level of massactivity at the time of production as level 1 orlevel 2, with a view to their conditioning forconversion into packages.

Level 1 wastes or packages are those which,following solidification or immobilization, and asof the date of conditioning, have mass activityvalues equal to or lower than those in Table 1. Allthose wastes or packages whose mass activityexceeds these values at the time of conditioningmust be conditioned in accordance with thestricter quality requirements corresponding tolevel 2. As regards location in the DU, the wastesor packages are classified at level 1, 2 or 3. Given

Table 2General mass activity limit per disposal unit (bequerels pergram)

Nuclide Per DU

1.00×1063H14C 2.30×106

50Ni 6.30×104

63Ni 1.20×107

60Co 1.70×108

90Sr 9.10×104

94Nb 1.20×102

99Tc 4.30×105

4.10×101129I3.30×105137Cs3.70×103Total a at 300 years

that they do not affect the way in which condi-tioning is carried out by the producer, these activ-ity values will be updated in relation to inventoryat the date of collection of the correspondingwastes or packages. The limits for level 1 are asindicated in Table 1. The level 2 limits will dependon the configuration of the corresponding DUs,since they are derived from the limits establishedfor such units in the safety study (Table 2). Thelevel 2 limits in the case of homogeneous wastepackages contained in 220 l drums and immobi-lized in CE-2a containers are indicated in Table 3.

Configurations other than those indicatedabove (packages of different dimensions, com-paction pellets) in CE-2a containers will havedifferent derived limits which will be calculated ona case-by-case basis.

Table 3Level 2 limits for 220 l waste packages immobilized in CE-2acontainers (bequerels per gram)

3.5×1063H14C 8.0×106

2.2×10859Ni63Ni 4.2×107

3.2×10590Sr94Nb 4.2×102

99Tc 1.5×106

1.6×102129I137Cs 1.1×106

Total a at 300 years 1.3×104

Table 1Mass activity values for level 1 (bequerels per gram)

Total a activity 1.85×102

7.4×104Total b–g activity due to radionuclides witha period in excess of 5 years

Activity due to individual b–g emitters with 1.85×104

periods in excess of 5 years (except tritium)Tritium activity 7.4×103

A. Morales / Nuclear Engineering and Design 176 (1997) 177–180 179

Table 4Maximum mass activity for level 3 waste packages (Class Cwastes according to 10 CFR 61) (bequerels per gram)

Nuclide

1.3×10763Ni90Sr 1.3×108

8.5×107137CsTotal a at 300 years 3.7×103

� The wastes must not contain non-immobilizedliquids.

� They must not contain substances liable togenerate gases or exothermic reactions alteringthe postulated durability of the structures.

� They must not contain substances whose maxi-mum potential hazard does not arise as a resultof radioactivity.

� The radiological limits established in the safetystudy shall not be exceeded.

4.3. Acceptance criteria linked to qualityobjecti6es

� All wastes must be duly identified.� All wastes must, after conditioning or per se,

have a mechanical resistance to quantified onthe basis of activity classification.

� All wastes must, after conditioning or per se,have a resistance to contact with water andshall, as from a given level of activity, meetcertain limits in relation to leaching rates in thepresence of water.

� Certain durability-related criteria may be ap-plied to some wastes, depending on their activ-ity and type of container.

5. Quality controls associated with wasteacceptance

In relation to the acceptance of typified wastepackages, and following approval of the corre-sponding process book, a series of activities willbe performed periodically in order to ensure com-pliance by the producer with the limits establishedby the acceptance criteria. The most important ofthese are as follows: analysis of samples of non-conditioned wastes; production controls; super-controls.

5.1. Analysis of samples of non-conditionedwastes

In relation to the different waste streams associ-ated with an approved process book, the producerwill be requested to provide waste samples priorto initiation of the corresponding conditioning

There is a level 3 for waste packages exceedingthe limit values for level 2 but not those indicatedin Table 4, which are equivalent to the valuesindicated for class C in 10 CFR 61. These pack-ages must be located in the DUs such that theseunits do not exceed the limit for level 2 includedin the safety study (see Table 2).

4. Acceptance criteria for packages containingconditioned wastes

4.1. General

In order to ensure compliance with the secondof the premises included in the introduction, i.e.,that the wastes be duly conditioned in the DUs, itis necessary for the solid or solidified wastes tomeet a series of requirements that make up theacceptance criteria.

These criteria are of two types: some are obliga-tory for all types of wastes and are related to thesafety objectives of the disposal facility, whileothers depend on the classification of the wastesand are related to quality objectives. Non-compli-ance with the latter should be analysed in view ofthe contribution made by the other elementsforming the DU (mainly the container).

4.2. Acceptance criteria relating to safetyobjecti6es

� The activity of the wastes should be quantifiedby significant radionuclides, in accordance withthe facility’s reference inventory.

� The wastes must be compatible with the mate-rials used for the DUs.

A. Morales / Nuclear Engineering and Design 176 (1997) 177–180180

campaigns. The frequency of these samples, whichwill be established beforehand, will depend on thetype of waste stream and on the characteristics ofthe production installation.

These samples are analysed and the results areused to verify compliance with the limits for a

emitters and to verify the validity of the correla-tion factors used to determine other significantradionuclides.

5.2. Production controls

These controls are carried out at the productioninstallations themselves, in coordination with theproduction campaigns, and are aimed at verifyingcompliance by the producers with the conditionsestablished in the corresponding DDBs and ofsignificance as regards assurance of waste packagequality.

On completion of each production control adetailed report is drawn up, and the producer isnotified of whatever aspects are to be modified,where applicable.

The frequency of the controls, per waste streamwith associated approved DDB and installation,depends on the operating conditions of eachplant.

5.3. Supercontrols

These consist of destructive tests carried out onaccepted packages already received at the disposalfacility, aimed at verifying compliance with safetycriteria related aspects.

These controls shall be focused mainly on de-termination of waste package activity, using sam-ples of powder extracted by perforation, and onverification of other physicochemical characteris-tics of the tested matrixes.

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