Improvements on Low Level Activity Gamma Measurements and X-ray Spectrometry at the CEA-MADERE Measurement Platform

Victoria Sergeyeva,Jonathan Bonora,Hervé Philibert,Christophe Domergue,Jean Michel Girard,Nicolas Thiollay,Christophe Destouches,Abdallah Lyoussi

doi:10.1051/epjconf/201610605011

Abstract

The CEA MADERE platform (M easurement A pplied to D osimE try in RE actors) is a part of the Instrumentation Sensors and Dosimetry Laboratory (LDCI). This facility is dedicated to the specific activity measurements of solid and radioactive samples using Gamma and X-ray spectrometry. MADERE is a high-performance facility devoted to neutron dosimetry for experimental programs performed in CEA and for the irradiation surveillance programmes of PWR vessels. The MADERE platform is engaged in a continuous improvement process. Recently, two High Efficiency diodes have been integrated to the MADERE platform in order to manage the accurate low level activity measurements (few Bq per sample). This new equipment provides a good level of efficiency over the energy range from 60 keV to 2 MeV. The background continuum is reduced due to the use of a Ultra Low Background (ULB) lead shielding. Relative and absolute X-ray measurement techniques have been improved in order to facilitate absolute rhodium activity measurement (Rh103m ) on solid samples. Additional efforts have been made to increase the accuracy of the relative niobium (Nb93m ) activity measurement technique. The way of setting up an absolute measurement method for niobium is under investigation. After a presentation of the MADERE's measurement devices, this paper focuses on the technological options taken into account for the design of high efficiency measurement devices. Then, studies performed on X-ray measurement techniques are presented. Some details about the calculation of uncertainties and correction factors are also mentioned. Finally, future research and development axes are exposed.

Highlights

This facility is dedicated to the specific activity measurements of solid and radioactive samples using Gamma and X-ray spectrometry
Relative and absolute X-ray measurement techniques have been improved in order to facilitate absolute rhodium activity measurement (Rh103m) on solid samples
MADERE is accredited by the French Accreditation Committee (COFRAC) for Gamma measurements of standard level specific activity and relative measurements by X-ray spectrometry

Summary

Introduction

In mock-ups conditions, the activity obtained on the dosimeters is very weak. Due to this MADERE developed procedures and optimised its equipment for performing low level activity Gamma measurements. Measurement methods of X-ray emitters have been upgraded in order to allow the use of Rhodium dosimeter. The latter gives access to the intermediate neutron energy spectrum (0.7 MeV–1 MeV) in the mock-up reactor. While X-ray measurements for Nb93m are obtained by a relative method, the X-ray measurements for Rh103m must be performed by an absolute method. In order to manage an absolute X-ray measurement for Rh103m, MADERE performed some equipment optimisation and improved spectrum treatment and analysis

MADERE Platform

Low Level Activity

Measurement Methods and Optimization

Correction Factors and Uncertainties

Findings

Conclusions