SYSTEM PERFORMANCE ASSESSMENTS FOR RADIOACTIVE WASTE DISPOSAL

							       Proceedings of the NEA Workshop on

SYSTEM PERFORMANCE ASSESSMENTS
 FOR RADIOACTIVE WASTE DISPOSAL




                           PARIS
                 22nd - 24th October 1985




                 NUCLEAR ENERGY AGENCY
ORGANISATION FOR ECONOMIC CO-OPERATION AND DEVELOPMEN1
                                   FOREWORD



       Currently one of the most important areas of radioactive waste manage-
ment is research and development directed towards assessments of the perfor-
mance of potential radioactive waste disposal systems. It is primarily for
this reason that, under the guidance of its Radioactive Waste Management
Committee (RWMC), the OECD Nuclear Energy Agency has devoted a considerable
amount of effort towards the further development of systems performance
assessment methodologies. The first NEA workshop on this topic, which was
held in 1982, critically reviewed the status of performance assessment meth-
odologies in both their generic and site-specific aspects in order to provide
guidance for the further development of predictive mathematical models and
also to facilitate comparison of different approaches to modelling and bet-
ween safety assessments of alternative disposal options. The resultant infor-
mal report* identified the various approaches adopted in OECD Member countries,
highlighted some of the problems foreseen in carrying out assessments and
made recommendations on future needs.

       In the interim since the first workshop, new challenges have arisen
which stem from a concerted effort throughout the OECD area to develop and
apply performance assessment methodologies, including some full scale assess-
ments of potential disposal systems within several Member countries. A small
group of consultants was assembled to consider these developments and, to-
gether with the NEA Secretariat, develop the most appropriate theme for a
second NEA workshop. As a result, it was considered that due to the number of
different approaches being followed, a major problem was how to rationalise
all the various elements involved in carrying out performance assessments.
This rationalisation was necessary in order to help generate confidence in
predictions of the performance of waste disposal systems. It was therefore
agreed that the workshop would examine the links or interrelationships bet-
ween the major components of performance assessments, in particular the
following :

       -   the link between performance assessments and regulatory requirements ;
       -   the links between mathematical models used in performance assess-
           ments ;
       -   the link between model development and field/laboratory observations.

       These proceedings reproduce the papers presented at the Workshop to-
gether with a summary and conclusions prepared by the NEA Secretariat in con-
junction with rapporteurs appointed for each session and the Chairman. The
opinions expressed are the responsibility of the authors and it no way commit
the Member countries of the OECD.

* This report is available on request from the OECD/NEA Secretariat,
  38 boulevard Suchet, 75016 Paris, France.