New article published in 12(4B) - ENFIR/INAC 2024

Proposal for Safety Classification of SSC for Land-Based Facilities to Support Nuclear-Powered Submarines

Abstract: The design of land-based facilities to support nuclear-powered submarines involves complex regulatory challenges due to the unique combination of nuclear, military, and naval aspects. The focus of this paper is the proposal for the safety classification of SSC (Structures, Systems, and Components) in these facilities, described as "non-conventional". These SSC are initially designed for maritime/naval operations but due to their structural or functional interface with nuclear aspects of the supported submarines, require a more thorough evaluation to define their significance for safety and the need for additional requirements. The proposal evaluates specific conditions of joint operation between the land support SSC and the submarine’s inherent SSC, based on American Nuclear Society (ANS) standards, to establish a simplified procedure for the preliminary safety classification of non-conventional SSC. This analysis emphasizes the importance of considering additional requirements to preserve structural integrity and ensure the safety of these facilities. Overall, the proposed safety classification procedure aims to provide guidance for the design and licensing of land-based facilities that support nuclear-powered submarines. As a result, a safety classification proposal is presented for the following SSC (non-conventional for a nuclear facility): quays, pontoons, fenders, crane, dry dock, dry dock gate (caisson), keel blocks, dry dock drainage system, electric power system for the submarine (at quay and the dry dock), cooling water system for the submarine (at quay and the dry dock), and Additional containment (to access the reactor section). Read full article. 

Comparison of ion exchange methods for lithium-7 isotopic enrichment for application in PWR reactors

Abstract: ⁷Li in the form of lithium hydroxide monohydrate (LiOH·H₂O), remains liquid over a wide temperature range (180 to 1340ºC), making it an excellent pH controller on reactor coolant in Pressurized Water Reactors (PWRs). In contrast, ⁶Li is a strong neutron absorber and unsuitable for PWRs, whereas ⁷Li has a low neutron cross-section, making it ideal for reactor use. Enriching ⁷Li to over 99.95% is essential but complex. The Colex method, involving mercury, was used for enrichment but was banned in the USA due to environmental concerns. Currently, Russia and China are the primary sources of enriched ⁷Li. A mercury-free procedure to obtain this isotope is necessary, ion exchange techniques, including frontal analysis, elution, and displacement chromatography, offer alternative enrichment methods. This study evaluates these techniques to achieve the required ⁷Li enrichment for PWR applications. Preliminary results showed an abundance of ⁷Li at 95.65% after displacement of 830 cm.  Read full article.