THE COMMISSION OF THE EUROPEAN COMMUNITIES. Denitration of Radioactive Liquid Waste

Transcription

1 THE COMMISSION OF THE EUROPEAN COMMUNITIES Denitration of Radioactive Liquid Waste

2 Proceedings of a seminar jointly organised by the Commission of the European Communities, Directorate-General for Science, Research and Development, and the Kernforschungsanlage JOlich GmbH, in the framework of the R&D programme on radioactive waste management and disposal, held in KFA JOlich, Federal Republic of Germany, December Chairmen: R. KROBEL (KFK) H. DWORSCHAK (CEC) E. MERZ (KFA) Secretaries: L. CECILLE (CEC) S. HALASZOVICH (KFA)

3 Radioactive Waste Management Series DENITRATION OF RADIOACTIVE LIQUID WASTE edited by L. CECILLE Commission of the European Communities, Directorate-General for Science, Research and Development, Nuclear Fuel Cycle Division and S. HALASZOVICH Kernforschungsanlage Julich GmbH published by Graham & Trotman for the Commission of the European Communities

4 Published in 1986 by Graham & Trotman Ltd Sterling House 66 Wilton Road ldndon SW1V 1DE UK Graham & Trotman 101 Philip Drive AssInlppl Park Norwell, MA USA for the Commission of the European Communities, Directorate-General Telecommunications, Information Industries and Innovation, Luxembourg EUR ECSC, EEC, EAEC, Brussels and Luxembourg, 1986 British Library Cataloguing in Publication Data Denitration of radioactive liquid waste. 1. Radioactive waste disposal 2. Nitrification I. Cecille, L. II. Halaszovich, S. III. Commission of the European Communities ' 38 TD898 ISBN ISBN (ebook) DOT / Legal Notice Neither the Commission of the European Communities, Its contractors nor any person acting on their behah, make any warranty or representation, express or Implied, with respect to the accuracy, completeness or usefulness of the Information contained In thla document, or that the use of any Information, apparatus, methods or process disclosed In this document may not Infringe privately owned rlghta; or assume liability with respect to the use of, or for damages resulting from the use of any Information, apparatus, method or process disclosed In this document. All rights reserved. No pan of this publication may be reproduced, stored In a retrieval system, or transmitted In any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without the prior permission of the publishers.

5 Introduction The purpose of the Seminar was to provide an international interdisciplinary forum for in-depth discussions on the pros and cons of a denitration step by chemical means in the course of solidification of MAW (medium active waste) and HAW (highly active waste), prior to feeding the calciner or melter. In particular, differences In the volatility of some components and aerosol formation during the vitrification step are of interest. Chemical rather than thermal denitration may have particular merits which could simplify off-gas purification. A reduction in the salt burden of waste solutions, leading to a reduction In the volume of solid waste, may also be achieved. The scientific programme of the Seminar consisted of invited lectures only, given by experts actively engaged in this field of research. The emphasis was on extensive discussions among the participants, with the aim of leading to an objective understanding of the state-of-the-art. The meeting also indentified issues and options for future research. v

6 Summary For some applications, such as concentration of high level liquid waste before interim storage, pretreatment of high level liquid waste prior to vitrification or actinide partitioning, and volume reduction of medium level liquid waste, the Implementation of a denltratlon process by means of formic acid or formaldehyde seems very worthwhile. Moreover, for reducing technetium and ruthenium volatility during vitrification of high level waste, denitratlon with sugar proved to be quite efficient as far as the rotary kiln calclner is concerned. However, although some applications - such as concentration of high level liquid waste - have been operating on an industrial scale for many years, denitration depends on careful control of the waste composition as well as the operating conditions to avoid the occurrence of secondary interfering reactions which could be detrimental to the safety of the process or prevent the achievement of the desired final acidity and off-gas composition. Following a description of the basic reactions which feature denitration and the identification of the main parameters acting on reaction rate and induction time, the various applications of denitration reactions in nuclear waste management envisaged or currently practised are extensively analysed in the various presentations to the Seminar. Finally, conclusions and recommendations are included which highlight those aspects deserving further investigations. vi

7 CONTENTS Introduction Summary v vi Session 1: Basic Reactions and General Application of Denitration - Overview on the application of denitration in the nuclear field E.R. MERZ - Chemical reactions involved in the denitration process with HCOOH and HCHO L. CECILLE and M. KELM 17 - Alternative organic reductants for denitration K. GOMPPER 38 - Economical aspects of denitration in the management of reprocessing concentrate H. KLONK and M. STEHLE 53 - Safety aspects about denitration T. SCHULENBERG 57 Session 2: Denitration of Reprocessing Concentrate - Denitration of reprocessing concentrates by means of HCHO S. HALASZOVICH, S. DIX and R. HARMS 64 - Denitration of reprocessing concentrate by means of HCOOH M. KELM, B. OSER and S. DROBNIK 92 - Application of denitration/oxalate precipitation in the Petra hot-cell facility G. VASSALLO, H. DWORSCHAK, F. SEGANTINI and A. FACCHINI Abatement of the NO. evolved during denitration of reprocessing concentrate A. DONATO 118 vii

8 Session 3: Denitratlon of High Level Liquid Waste - Denitration of HLLW for actinide partitioning L. CECILLE and M. LECOMTE Operational experience of the denitratlon of simulated highly active liquid wastes during vitrification M.C. JERVIS Reduction of Ru an Tc volatility during vitrification of HLLW by denitration A. JOUAN, J.P. MONCOUYOUX and S. HALASZOVICH Industrial application of denitration of HLLW by means of HCHO C. BRESCHET, D. PAGERON, F. DRAIN and V. DECOBERT Conclusions and opinion of the scientific secretaries List of participants 183 viii