Year
2012
Abstract
This paper presents, at first conceptual methods for the removal of melted fuel in the reactor and containment vessels of Units 1 - 3 of Fukushima-Daiichi NPP. By making the removal methods clear, several strata of removed MF could be categorized into slab type debris, cylindrical debris, small rock-like debris and particle-like debris. Two possible NDA technologies are described in terms of feasibility studies. One of the two is Neutron Resonance Densitometry (NRD) based on NRTA (Neutron Resonance Transmission Analysis) and NRCA (Neutron Resonance Capture Analysis) utilizing the TOF (Time of Flight) method, which is intended for the analysis of particle-like debris. This paper describes the proposed NRD very roughly, while another paper shows the details of this method [1]. The other NDA technology uses LCS (Laser Compton Scattered) gamma-rays (mono-energetic gamma-rays) to analyze other types of debris. The application of LCS gamma-rays by the Nuclear Resonance Fluorescence (NRF) method and is presented here roughly. The measurement technique of the scattered method with NRF is shown. A novel transmission measurement using NRF is also shown roughly, which has the advantage of being insensitive to the radioactive nature of the fuel and is completely insensitive to the geometry of the fuel. The techniques are discussed in other papers in more detail [2] [3].