INVESTIGATION ON THE DETERMINATION OF DISPOSAL CRITICAL NUCLIDES IN WASTE FROM PWR POWER PLANTS

Información del proyecto

Identificador del acuerdo de subvención: FI1W0225

Proyecto cerrado

Fecha de inicio 1 Agosto 1988

Fecha de finalización 30 Junio 1990

Financiado con arreglo a

• Research and development programme (Euratom) on the management and storage of radioactive waste, 1985-1989

Coste total

Sin datos

Aportación de la UE

Sin datos

Coordinado por

NATIONAL AGENCY FOR RADIOACTIVE WASTE AND ENRICHED FISSILE MATERIALS
Belgium

Objetivo

SAFETY STUDIES RELATED TO THE DISPOSAL OF LOW- AND INTERMEDIATE-LEVEL WASTE INDICATE THAT THE LONG-TERM RISK IS DETERMINED BY THE PRESENCE OF LONGER-LIVED NUCLIDES SUCH AS C14, NI59, NI63, SR90, NB94, TC99, I129, CS135, CS137 AND TRANSURANIUM ELEMENTS. AS MOST OF THESE NUCLIDES ARE VERY DIFFICULT TO MEASURE, THE CORRELATION BETWEEN THESE NUCLIDES AND OTHER EASILY MEASURABLE NUCLIDES HAS BEEN INVESTIGATED FOR SOME TYPICAL WASTE STREAMS, E.G. WASTE FROM THE OPERATION OF PWR POWER PLANTS, AND CORRELATION FACTORS HAVE BEEN PROPOSED BY SEVERAL AUTHORS. THE RANGE OF THESE FACTORS IS, HOWEVER, RELATIVELY LARGE FOR CERTAIN NUCLIDES, AND SOME OF THEM ARE RECOGNIZED TO BE PLANT-SPECIFIC.

THE OBJECTIVES OF THIS INVESTIGATION ARE:
1) TO VERIFY THE VALIDITY OF THE CORRELATION FACTORS ON THE RELATIVELY HOMOGENEOUS RANGE OF PWR POWER PLANTS OPERATED IN BELGIUM,
2) TO ESTABLISH THE NECESSARY TECHNIQUES TO ASSAY, BOTH IN A PRACTICAL AND RELIABLE WAY, THE CONCENTRATIONS OF THESE NUCLIDES FOR THE MAIN WASTE STREAMS.
Research has been conducted in Belgium on the main waste streams arising from the operation of pressurized water reactor (PWR) power plants, in order to assay, both in practical and reliable way, the concentrations of a number of longer lived nuclides such as carbon-14, nickel-59, nickel-63, strontium-90, niobium-94, technetium-99, iodine-129, caesium-135, caesium-137 and the transuranium elements. The aim was to evaluate the possibility of deducing the concentrations of the longer lived critical nuclides from the data on easily measurable key nuclides such as cobalt-60 and caesium-137, eg by gamma spectrometry on conditioned drums.

A number of samples from representative batches of primary water, evaporator concentrates, ion exchange resins and filter cartridges were c ollected at the different PWR power plants operated in Belgium and destructively analysed in order to determine their content of critical nuclides and key nuclides. In parallel, a number of cemented drums made from the same batches were examined by gamma spectrometry in order to confirm the concentrations of key nuclides determined by destructive analysis. As an additional verification, some of these conditioned drums were core drilled and the samples analysed destructively.

For homogeneously embedded waste, the key nuclides such as cobalt-60 and caesium-137 could be assessed with a satisfactory precision by gamma spectrometry; the precision was worse when the waste was not homogeneous. Most of the critical nuclides could only be determined by destructive analysis after complex preparation of the waste samples. For iodine-129 and technetium-99, and to a lesser extent for strontium-90 and total alpha activity, the coherence of the results obtained so far is poor. Certain critical nuclides, such as the corrosion products, correlate well with the key nuclides; for most of the measured fission products, clear correlations could not be established, essentially due to the measurement uncertainties. O n the basis of the activities measured, nickel-63, nickel-59, carbon-14, technetium-99, iodine-129 and total alpha appear to be important for the classification of the PWR wastes.
1. INVESTIGATION ON NON-CONDITIONED WASTE.
1.1. DETERMINATION OF APPROPRIATE SAMPLING METHODS AND COLLECTION OF SELECTED REPRESENTATIVE SAMPLES OF PRIMARY WATER, EVAPORATOR CONCENTRATES, ION EXCHANGE RESINS AND FILTER CARTRIDGES IN THE DIFFERENT POWER PLANTS OPERATED IN BELGIUM.
1.2. PREPARATION AND RADIOCHEMICAL ANALYSIS OF THE SAMPLES IN ORDER TO MEASURE THEIR CONTENT OF C14, NI59, SR90, NB94, TC99, I129, CS135, CS137 AND TRANSURANIUM ELEMENTS.
1.3. ON THE BASIS OF THE RESULTS, DETERMINATION OF AN ANALYSIS METHOD THAT CAN BE INDUSTRIALLY APPLIED.
1.4. PRELIMINARY INVESTIGATION OF THE POSSIBLE VARIATIONS IN THE RADIOLOGICAL COMPOSITION OF THE WASTE AS A FUNCTION OF PLANT-SPECIFIC PARAMETERS.

2. INVESTIGATION ON CONDITIONED WASTE.
2.1. PREPARATION OF A SET OF TEN FULL-SCALE PACKAGES CONTAINING REPRESENTATIVE SAMPLES OF CEMENTED EVAPORATOR CONCENTRATES, I-X RESINS AND FILTERS. IF POSSIBLE, THE PACKAGES ARE PREPARED FROM THE SAME WASTE BATCHES AS THOSE ANALYSED IN THE FIRST PART OF THE PROGRAMME.
2.2. NON-DESTRUCTIVE EXAMINATION OF THE WASTE PACKAGES BY GAMMA-SPECTROMETRY WITH THE AIM OF MEASURING THE QUANTITY OF CS137 AND CO60 INCLUDED.
2.3. ASSAY OF THE DISPOSAL CRITICAL RADIONUCLIDES INCLUDED IN A SELECTION OF THESE PACKAGES BY DESTRUCTIVE ANALYSIS (CORE DRILLING AND ANALYSIS AS PER 1.2. ABOVE).
3. COMPARISON OF THE RESULTS OBTAINED BY DESTRUCTIVE ANALYSIS ON NON-CONDITIONED WASTE, NON-DESTRUCTIVE AND DESTRUCTIVE ANALYSIS ON CONDITIONED WASTE PACKAGES. VERIFICATION OF THE APPLICABILITY OF CORRELATION FACTORS.

Ámbito científico (EuroSciVoc)

• ciencias naturales › ciencias físicas › física nuclear › fisión nuclear
• ciencias naturales › ciencias químicas › química nuclear › química de la radiación

Programa(s)

• FP1-RADWASTOM 3C - Research and development programme (Euratom) on the management and storage of radioactive waste, 1985-1989

Tema(s)

Datos no disponibles

Convocatoria de propuestas

Datos no disponibles

Régimen de financiación

CSC - Cost-sharing contracts

Coordinador

NATIONAL AGENCY FOR RADIOACTIVE WASTE AND ENRICHED FISSILE MATERIALS

• Aportación de la UE: Sin datos
• Dirección: 01,Avenue des Arts 14 ; 1210 BRUXELLES ; Bélgica
• Coste total: Sin datos