Results from the CDE phase activity on neutron dosimetry for the international fusion materials irradiation facility test cell

The international fusion materials irradiation facility (IFMIF) project dea ls with the study of an accelerator-based, deuterium-lithium source, produc ing high energy neutrons at sufficient intensity and irradiation volume to test samples of candidate materials for fusion energy reactors. IFMIF would also provide calibration and validation of data from fission reactor and o ther accelerator based irradiation tests. This paper describes the activity on neutron/gamma dosimetry (necessary for the characterization of the spec imens' irradiation) performed in the frame of the IFMIF conceptual design e valuation (CDE) neutronics tasks. During the previous phase (conceptual des ign activity (CDA)) the multifoil activation method was proposed for the me asurement of the neutron fluence and spectrum and a set of suitable foils w as defined. The cross section variances and covariances of this set of foil s have now been used for tests on the sensitivity of the IFMIF neutron spec trum determination to cross section uncertainties. The analysis has been ca rried out using the LSL-M2 code, which optimizes the neutron spectrum by me ans of a least-squares technique taking into account the variance and covar iance files. In the second part of the activity, the possibility of extendi ng to IFMIF the use of existing on-line in-core neutron/gamma monitors (to be located at several positions inside the IFMIF test cell, for beam contro l, safety and diagnostic purposes) has been studied. A feasibility analysis of the modifications required to adapt sub-miniature fission chambers (rec ently developed by CEA-Cadarache) to the high flux test module of the test cell has been carried out. The verification of this application pertinence and a gross definition of the in-core detector characteristics are describe d. The option of using self-powered neutron detectors (SPNDs) is also discu ssed. (C) 2000 Elsevier Science B.V. All rights reserved.