[en] Passive Institutional Controls (PICs) are markers and archives designed to warn and inform future generations about the location, purpose and to some extent the content of a repository. These warnings are addressed to potential intruders into deep geologic repositories, advertent and inadvertent. Current thought is that rather than attempt to manipulate the emotions of future generations through ominous symbolic warnings, the structures and messages ought to inform those generations that the content of the repository is dangerous and useless. The presenter raised the issue that although careful efforts were made to show that there is no valuable resources in Yucca Mountain, it is undeniable that a repository project involves a massive amount of valuable materials. It was asked why markers were labelled 'passive' controls. It was explained that under EPA definitions, 'active' controls cover the use of fences, gates, and guards; essentially, those structures and systems which imply continued human presence. Markers are 'Passive Institutional Controls' because they are intended to fulfil their purpose without the need for anyone to remain on site. In discussing this specific understanding of 'passive' and 'active' controls, the comment was made that there had been no mention of the fact there are going to be regulators and institutions for a long time; neither had the presentation discussed the role local communities could play with regards to monitoring and record keeping. It was suggested that the focus remained too strongly on passive controls. It was suggested that it would be better to see the marker system as the redundancy in the event that all continuity - of institutions or of community - was broken. It was suggested furthermore that there should be some agreed terminology which expressed this scenario. In response to the comment on using the local communities, Van Luik explained there was a reluctance to rely on the community in question, because as it is highly dependent on the presence of the oil and gas industry and WIPP. The difference between the USA and Europe, with regards to climate and the density of the population, was raised. It was argued that in the different circumstances, the notion of guardianship was unworkable. Another context related matter was pointed out: Yucca Mountain uses the WIPP design with regard to PIC's, but adapted to a mountain environment: there is collaboration on design and messages, but materials have to be adapted to localities. The ethical dimension was also touched upon throughout the presentation and subsequent discussion. It was stated that markers, monuments and archives are the ethical thing to do by this generation, as long as they are not unreasonable for this current society in terms of cost and effort. Clarification was requested on the relative cost of preventing a potential death in 10 000 years and saving someone today (cf. Appendix D Nordic Studies). The possibility of future generations misusing markers was also raised - for example, if they became collectable. It was argued that one's moral responsibility had been fulfilled once you have put a warning in place. This position was contested, as there are plenty of examples of warnings failing - for example, those at the entrance to pyramids did not deter grave robbers. The response was that it was important to learn from such examples and try and create more resilient warnings. For example, current thinking on the subject favours trying to inform future generations, rather than trying to scare people away. If our best efforts fail, we have still met our moral responsibility. The example of the failure of the tsunami markers in Japan was given in this context: although they failed, older generations did their duty, their ethical obligation to future generations. Some more factual issues were also clarified: WIPP called a 'pilot plant', because in the beginning it was, and now the name is kept because of its illustrative function. WIPP is now half full. EPA requires WIPP to have 10 000 year lasting markers, whereas Yucca Mountain legislation said 'as long as possible'. In response to the comment on using the local communities, Van Luik explained there was a reluctance to rely on the community in question, because as it is highly dependent on the presence of the oil and gas industry and WIPP, activities that cannot be relied on to support a community thousands of years into the future

[en] The Waste Isolation Pilot Plant is located about 42 kilometers from the city of Carlsbad, New Mexico. It is an operating deep geologic repository in bedded salt 657 meters below the surface of the Chihuahuan desert. Since its opening in March of 1999, it has received about 12,000 shipments totaling about 91,000 cubic meters of defense related transuranic (TRU) wastes. Twenty-two sites have been cleaned up of their defense-legacy TRU waste. The WIPP's shipping program has an untarnished safety record and its trucks and trailers have safely traveled the equivalent of about 60 round-trips to the Moon. WIPP received, and deserved, a variety of safety accolades over its nearly 15 year working life. In February of 2014, however, two incidents resulted in a major operational suspension and reevaluation of its safety systems, processes and equipment. The first incident was an underground mining truck fire, followed nine days later by an airborne radiation release incident. Accident Investigation Board (AIB) reports on both incidents point to failures of plans, procedures and persons. The AIB recommendations for recovery from both these incidents are numerous and are being carefully implemented. One major recommendation is to no longer have different maintenance and safety requirements for nuclear handling equipment and mining equipment. Maintenance and cleanliness of mining equipment was cited as a contributing cause to the underground fire, and the idea that there can be lesser rigor in taking care of mining equipment, when it is being operated in the same underground space as the waste handling equipment, is not tenable. At some point in the future, the changes made in response to these two incidents will be seen as a valuable lesson learned on behalf of future repository programs. WIPP will once again be seen as a ''pilot'' in the nautical sense, in terms of 'showing the way' - the way to a national and international radioactive waste management solution. The operational lessons learned from these two incidents will be available to be shared with other geologic repository programs. Neither of these two operational incidents call into question the suitability of rock salt as a repository host rock. Both incidents point to a need to take care to evaluate all potential consequences in making decisions about underground equipment maintenance and housekeeping, and to make a greater effort to assure that measures are taken to mitigate lower likelihood events and to practice emergency egress procedures until they are second nature to the workforce.

[en] The session started with Abe Van Luik (IGSC Chair, US-DOE-YM, USA) who presented the feedback of the international peer review of the US-DOE Yucca Mountain TSPA (Total System Performance Assessment) supporting the successful designation of the site by the Congress and the President of the U.S. In particular, he listed key implications of the IRT (International Review team) recommendations on the forthcoming US-DOE documentation of its case for safety to be submitted to the regulator, the U.S. Nuclear Regulatory Commission, mainly: - The documentation submitted to the licensing authority should address technical aspects and compliance with regulatory criteria. - That documentation should reflect sound science and good engineering practice; it should present detailed and rigorous modelling. - In addition, it should present both quantitative and qualitative arguments, make a statement on why there can be confidence in the face of uncertainty, acknowledge remaining issues and provide the strategy to resolve them. - Demonstrating understanding is as important as demonstrating compliance. - There is a need to provide a clear explanation of the case made to the regulator for more general audiences to complement the large amount of technical documents that will be produced. The US-DOE response to these recommendations for the License Application, which is under preparation, is that the recommendations will be implemented to the maximum extent possible. In subsequent discussion, with respect to the License Application, it was acknowledged that detailed guidance from the U.S. regulator was very useful, and guidance of this type would be generally useful. At the current time, the words 'safety case' are not mentioned in U.S. regulations, but if one reads both the regulation and guidance documents it becomes evident that all aspects of a safety case need to be provided in the License Application and its accompanying documents

[en] Abe Van Luik (IGSC Chairman, US-DOE-YM) gave a quick overview of the status of the IGSC safety case brochure titled: 'The Nature and Purpose of the Post-closure Safety Case in Geological Disposal'. The need for IGSC member review, and the schedule for the review process, was explained. The objective was to have a document to present to the March 2004 RWMC meeting for its approval. In discussion it was noted that this document was in good agreement with the safety case content of the Safety Requirements document described by the preceding presenter. It accurately paraphrases the IAEA document's definition and expands on the idea of a safety case without contradiction of that document

[en] Abe van Luik (DOE, USA) stated that the U.S. Department of Energy is interested in P and T to the extent that transmutation is technically feasible and will reduce the toxicity of the waste to a point that makes it technically and economically justified. Therefore, research on P and T strategies incorporates the evaluation of its potential costs and benefits. A progress report to Congress (in preparation) will likely state that system studies in the USA and in Europe indicate a preference for reactor based transmutation rather than accelerator-driven systems. DOE proposes isolation of Cs and Sr, the recycling of Pu and Np in LWRs, and later the recycling of minor actinides in fast reactors. The report identifies the high-level waste volume reduction, the easier management of short-term heat load, the reduction of long-term heat load and radiotoxicity, and therefore long-term dose reduction as potential benefits. The goal of ongoing work is to quantify these benefits in order to allow an assessment of which alternatives can be economically useful in increasing the repository capacity, reducing the potential hazard from the repository and reducing uncertainties associated with the performance of the repository. This may, depending on the national nuclear power scenario, delay or avoid the need for a second repository for high-level waste in the USA. Furthermore DOE has received and is evaluating a proposal for simulation-based engineering to integrate all aspects of nuclear energy including reactor technology and waste disposal

[en] In US, and in particular for the DOE Yucca Mountain repository, monitoring is considered to be a significant element in the Performance Confirmation (PC) programme that focuses on the performance and functionality of the disposal system for the purposes of the licensing decision. Other testing and monitoring programmes may deal with other considerations such as increasing confidence or system optimisation aspects. The purpose of the performance confirmation is: - to develop a program of tests, experiments, and analyses to evaluate the adequacy of the information used to demonstrate safety, and - to demonstrate that the system and the sub-system components (i.e. barriers) are operating as anticipated. The performance confirmation activities are classified depending on their purpose e.g. engineering testing and evaluation (to verify the robustness and performance of engineered barriers), science testing and evaluation (to confirm modelling capacity, data etc.). For the license update to allow closure, there is a need to show that safety is still to be expected after closure, and that what has been said has been done. US-DOE has developed a decision analysis approach with aims as followed: - to provide a consistent and sound basis for evaluating and comparing performance confirmation activities; - to use a formal multi-attribute utility analysis in its first phase to develop test and monitoring 'portfolios' and in the second phase for management use. Phase one aims to assess the candidate activities against activity evaluation criteria (defined by the initial workshop participants consisting of technical investigators and performance assessment (PA) analysts and managers). During dedicated workshops, those participants estimate the utility of a specific activity, PA managers providing the necessary management value judgements by reviewing the overall utility. Phase two aims at developing and evaluating alternative portfolios (each candidate activity must demonstrate compliance with basic regulatory requirements and additional requirements such as cost-effectiveness, regulatory robustness and coverage). Phase three consists of selecting portfolios, and phase four consists of updating the program by, for instance, adding one or more activities on the basis of new information (flexibility principle). The performance confirmation activities plan will be regularly reevaluated and updated. Actually, from twenty activities, eleven were begun during the site characterisation (e.g. unsaturated zone testing) two of them will be carried out during the construction phase (e.g. seal testing) and seven activities will begin during operations (e.g. corrosion testing, drift inspection). The path forward for the Yucca-Mountain-DOE performance confirmation is mainly to define activities (what, when, where and how), to establish the expected baseline for performance confirmation activities (required by regulator), to identify and develop test plans and procedures, to develop an integration group to asses data as a whole, and to define process for defining, detecting and reporting variances and for deciding on the appropriate action

[en] Abe van Luik (US DOE-YM, USA) presented the preliminary results of the Yucca Mountain international peer review of the Total System performance Assessments (TSPA) and a few preliminary indications of the issues. The peer review by 10 experts was organised by a joint secretariat formed by the NEA and the IAEA. Two meetings and three exchanges of questions and answers by E-mail between the meetings provided preliminary results that were orally presented at the end of August. The final report is due to the DOE by the end of January 2002. Abe Van Luik presented some unofficial examples of preliminary observations. As an example, he mentioned the reviewers' observation that uncertainties need an overall strategy for their evaluation and reduction. It was also mentioned that the documentation is not yet sufficiently transparent. An important issue for the review team was the ability to compare the safety evaluations of different nations' potential repositories. Finally, the reviewers made it clear that although the applicable regulation for this phase had been competently addressed, the documentation was not a safety case. Several shortcomings kept it from being a safety case, noteworthy being the lack of a statement on confidence, and a description of the basis of that confidence

[en] The US government released its 'Strategy for the Management and Disposal of Used Nuclear Fuel and High-Level Radioactive Waste' (the Strategy) in January 2013 (US DOE, 2013). The Strategy is a policy statement that acknowledges that the previous federal government approach to siting major nuclear waste management facilities is not workable. Experience has shown that this previous top-down approach typically does not work if opposition is strong at high levels of local and regional/state government. The newly published strategy presents a way to create a more acceptable and sustainable program to create an integrated system for transporting, storing and disposing of the higher-level wastes generated in both the civilian and the government sectors. (authors)

[en] Abe van Luik (US DOE- YM, USA), ended the presentation by giving feedback from the IAEA peer review on the biosphere modelling strategy developed by the DOE Yucca Mountain Site Characterisation Office (YMSCO). This review was based on available international standards and guidance. The peer review team was constituted of both experts from regulatory and waste management organisations and national advisory committees. The implementation of the review consisted of an examination of biosphere reports mainly regarding the modelling and question and answer exchanges. The final report was submitted in April 2000. It contained twenty-three recommendations within two broad classifications; one concerning the regulatory framework, the other one regarding the framework to increase stakeholders' confidence in modelling. The three main categories of recommendations were outlined, namely (i) the DOE' s Biosphere assessment Approach, (ii) the definition of the biosphere system, and (iii) the model development, data and results. Regarding in particular the treatment of the uncertainties in the biosphere, it was viewed as a key issue during the review and thus it will be re-evaluated in the future performance assessment. The summary highlighted most of the recommendations received are to be acted on, and are to be included in the License Application plan for biosphere modelling

[en] The complex formation of NpO₂⁺ with carboxylates: oxalic acid (Ox), malonic acid (Mal) succinic acid (Suc); glutaric acid (Glu), methylmalonic acid (Memal), oxydiacetic acid (ODA), TDA (thiodiacetic acid) and citric acid (Cit) and aminocarboxylates: iminodiacetic acid (IDA), methyliminodiacetic acid (MIDA), nitrilotriacetic acid (NTA), 2-hydroxyethylethylenediamine triacetic acid (HEDTA), ethylenediaminetetraacetic acid (EDTA) and diethylenetriaminepentaacetic acid (DTPA) was studied by solvent extraction in 6.60 m NaClO₄ at 25 C. The formation of only the 1: 1 NpO₂⁺ complex was observed with the ligands under investigation. The complexation of NpO₂⁺ with Ox, IDA, ODA and TDA was also measured at variable temperatures ranging from 25-60 C in 6.60 m NaClO₄. Results show that the complexation of NpO₂⁺ with these ligands increases with increasing temperature. The enthalpy and entropy of complexation of NpO₂⁺ were calculated from the temperature dependence of the stability constants using the Van't Hoff equation. Additionally, the formation of an aqueous ternary complex of the form NpO₂(X)(L) (X = EDTA or HEDTA; L = Ox or ODA) was identified for NpO₂⁺ at 25 C. Stabilities of these complexes are measured and discussed in term of their structures and basicities.