The Nuclear Decommissioning Authority

  Glass durability in high pH environments: A review of the literature C. Utton, R.J. Hand, N.C. Hyatt and S.W. Swanton SERCO / TAS / 003133 / 001  13859562 2011 (2.35mb)
Vitrification of some intermediate-level UK wastes is currently being investigated as a potential option for waste immobilisation and conditioning. Vitrification is being considered as it may offer the potential benefit of volume reduction compared to immobilisation with cement grouts. It may also reduce uncertainty associated with the long-term degradation of some wastes such as organic materials. One option for the disposal of the resulting vitrified ILW product would be to place it in a geological disposal facility (GDF) in a high pH environment with cemented ILW and a cementitious backfill. However, at present there is a lack of information on vitrified waste-cement interactions, in particular the consequences of the high pH of cement pore solution. Hence this report reviews the current understanding of the aqueous durability of vitrified and vitreous wasteforms with a particular emphasis on the effects of highly alkaline conditions as an input to future optimisation studies for a GDF. Durability test methods are reviewed and, as most durability studies on glasses have been conducted on vitrified high-level waste (HLW), the durability of vitrified HLW along with other vitrified and vitreous wastes is examined in detail. The performance of glasses in cement and concrete is also reviewed. Overall the literature suggests that highly-alkaline conditions, such as those provided by a cement-based near field, could have an adverse effect on the performance of vitrified ILW<br /><br />

  Implications of RWMD 500 year waste container integrity target compared with 150 years for container design and cost BT Swift, N Simpson, C-F Tso, NR Smart, PB Bamforth, M Jones and M Hubbert SERCO / 005084 / 001, Issue 1  15832227 2012 (2.95mb)
The Nuclear Decommissioning Authority (NDA) concepts for storage and disposal of packaged waste have evolved over the last few decades, so that both the maximum potential period of interim storage and the maximum potential period of exposure to an underground operational environment before a disposal facility is closed have been extended. Previously, containers were expected to maintain their integrity during interim storage for a period of up to 50 years, followed by 50 years in the operational period of a geological disposal facility (GDF) and 50 years after backfilling to allow for decay of short-lived radionuclides. This is consistent with the target of 150 years given by regulatory guidance. More recently, the maximum timescales have been extended. The current Generic Waste Package Specification (GWPS) calls for a target total container lifetime of 500 years, based on extended periods of up to 150 years of surface storage and up to a few hundred years after placement in a GDF prior to potential backfilling. The issue considered in this report is whether current designs of intermediate-level waste (ILW) containers will maintain their integrity under normal conditions for the extended total periods indicated by the current GWPS (i.e. 500 years compared to 150 years), and, if not, whether designing and manufacturing containers with the modifications required to ensure the required integrity under normal conditions has significant cost implications for waste producers.<br /><br />

  124857-06 Breakup vs Flow i1 020911 - FINAL COPY (3.57mb)
Breakup vs Flow i1 020911 - FINAL COPY

  2010-15-1B Peer Review of RWMDs DSSC Analysis of Comment Resolution Version 1 1 - 12 Jan 2011 (233kb)
RWMD has developed a suite of safety case reports for a future geological disposal facility (GDF), referred to as the generic Disposal System Safety Case (DSSC). The DSSC addresses the safety of waste transport and disposal operations, as well as the safety of the GDF in the long term after the facility has been closed. Because a specific site for a GDF has not been identified, the DSSC is based on a set of assumptions regarding possible host rocks and facility designs. In accordance with best practice in the development of such safety cases, RWMD has commissioned an external peer review of the DSSC reports. The peer review has been conducted in two phases by a multi-disciplined panel of suitably qualified and experienced reviewers. The first phase of peer review involved examination of draft versions of the DSSC reports during May and June 2010. In the first phase of its review, the peer review panel identified a large number of comments and some reservations on the draft DSSC reports and on some of the analyses they presented. A report from the first phase of peer review was completed and provided to RWMD on 1 July 2010. Following the first phase of peer review, RWMD continued to develop the DSSC documents to address comments received from the peer review panel and from various other groups and organisations. A second phase of peer review panel has been coordinated by TerraSalus Ltd. This involved reviewing later drafts of the DSSC documents, and examining the extent to which peer review comments had been addressed. RWMD has addressed most of the key peer review comments. The presentation of the aims, objectives and achievements of the DSSC has been improved and now seems appropriate. The DSSC collates and integrates a considerable body of information from across the waste disposal programme and for a wider range of wastes and potential waste materials than has been considered previously in the UK.

  A review of decision-making on spent nuclear fuel reprocessing internationally October 2011.pdf (134kb)
This Technical Note was produced by Galson Sciences Limited as part of an ongoing programme of research conducted by the Nuclear Decommissioning Authority (NDA)<br />and its contractors. It is a component of the research into the implementation of geological disposal for radioactive wastes in the UK. Reprocessing of spent nuclear fuel leads to the separation of uranium and plutonium from the spent fuel. The separated uranium includes a range of uranium enrichments, some of which may be used to make fresh nuclear fuel. Depleted, natural and low-enriched uranium is currently stored, although it could be enriched or used to make mixed oxide (MOX) fuel. The plutonium could also be used to make MOX fuel, but is currently stored. In addition, reprocessing produces highly active liquid wastes, which are vitrified for disposal as high-level waste (HLW); and intermediate-level waste (ILW), which is packaged for disposal. In the UK the majority of spent nuclear fuel is reprocessed. This technical note explores what factors have influenced other countries in their decisions as to whether or not to reprocess spent nuclear fuel, by examining four case study countries, namely Finland, France, Sweden and the US.

  A review of the information available to assess the risk of microbiologically influenced corrosion in waste packages May 2011 (2.44mb)
A review of the information available to evaluate the potential for microbiologically influenced corrosion (MIC) in radioactive waste packages has been carried out on the basis of information available in the technical/scientific literature. The work considers both the case of waste packages for HLW/spent fuel and packages for ILW/LLW in combination with different buffer materials (bentonite, cement, crushed rock, and magnesium oxide) and in a variety of possible geological conditions. The work considers the potential for environmental conditions to be favourable to the development of microbial activity in contact or in proximity of waste packages and the likely implications on the basis of the susceptibility of different materials. The review concludes that, in many circumstances, MIC is unlikely to have a more significant effect on the than other processes that are not microbially mediated. An appendix containing an analysis of techniques and methodologies available to study MIC is also presented.

  ADP02 Governance and Assurance Policy Rev3 (86kb)
This document sets out NDA’s requirements for Internal Audit within a Site Licence Company (SLC). It describes the context within which the NDA, Parent Body Organisations (PBOs) and SLCs operate, describes the NDA’s Internal Audit process and specifies mandatory requirements for PBOs and SLCs.

  An explanation of the differences between the 2007 derived inventory and equivalent wastes and materials in the 2010 UK Radioactive Waste Inventory (1.82mb)
This report explains the differences between the 2007 Derived Inventory and equivalent wastes and materials in the 2010 UK Radioactive Waste Inventory.

  An overview of the groups conducting research related to NDA's own activities - May 2011 (545kb)
This document presents an explanation of those groups that are in the direct control of the NDA, including the relationship of these groups, their scope and terms of reference and their membership.

  Annual Report and Accounts 2010/2011 (1.14mb)
NDA's annual report and accounts from 2010/11.