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Options and Technologies for Managing the Back End of the Research Reactor Nuclear Fuel Cycle (T33001)


Summary


This Coordinated Research Project (CRP) will review and summarize the options and technologies available for managing the back end of the research reactor nuclear fuel cycle. This project will achieve two key objectives. First, past work will be leveraged to identify and define a comprehensive set of short- and long -term strategies for managing the back end of the research reactor nuclear fuel cycle. Single-country strategies will be analysed by using a standard approach and compared to potential take-back regional and multinational options including commercially available or otherwise agreed back-end services. Second, the economic, technological and infrastructural requirements for enabling each strategy will be defined. The focus will be on matching options to the capabilities of countries with research reactors but lacking an industrial-scale civilian nuclear power industry. Country-specific case studies will be developed. Three research coordination meetings (RCMs) and two workshops will be held in order to socialize the strategies.
This CRP will also compare relevant technical approaches against IAEA Safety Standards as well as the Joint Convention on the Safety of Spent Fuel Management and on the Safety of Radioactive Waste Management. To enable this review, NS will be invited to participate in relevant meetings, RCMs and workshops via the link from NEFW/WTS through MP3. There is also the potential for this CRP to be following by an NS lead CRP that conducts a significantly more rigorous review of the detailed safety, security and safeguards challenges potentially applicable to different approaches. In this instance, NE could provide technical support via the same link.

Background situation analysis


The IAEA Research Reactor Database (RRDB) cites 247 operational research reactors worldwide including 159 in developed countries and 88 in developing countries. A further 19 are under temporary shutdown, while 6 are under construction and an additional 12 are planned. It is important to note that the challenge of managing research reactor spent fuel (RRSF) applies to Member States owning operational research reactors and also to Member States owning many of the 481 shut down and even decommissioned research reactors.

The RRDB shows that the research reactors’ power outputs span seven orders of magnitude, ranging from 1 X 10-5 MW to 100 MW. Although detailed data are not universally available, there is certainly also very wide variation in spent fuel burn-up histories, mass inventories and compositions.


An age distribution of the research reactors can be seen in this above figure

There is a much wider array of designs in use for research reactors than for power reactors, where 80% of the world's plants are of just two broadly similar types. Research reactor designs may feature pool or tank cooling systems, and some reactors are heavy water or graphite moderated. The range of coolant types and core geometries is accompanied by wide variation in the type, size, design and composition of research reactor fuel elements and assemblies. Plates or cylinders of uranium-aluminum alloy (U-Al) clad with pure aluminium are very common, as are pins of steel-clad U-ZrH, although U3Si2-Al - uranium silicide dispersed in aluminum are more common in LEU fuel. Research reactors also have different operating modes, for instance steady or pulsed, corresponding to the wide range of missions they are called upon to fulfill (http://www.world-nuclear.org/info/Non-Power-Nuclear-Applications/Radioisotopes/Research-Reactors/). A broad range of fuel burn-ups and corresponding radioactivity levels therefore prevails.

The key challenge, though, lies in the diversity of spent fuel locations and national/regional circumstances rather than mass or volume alone. Indeed, the inventories at issue are generally relatively small: in total, there are just over 3000 MW of capacity in all the existing research reactors. This is approximately the same thermal power output as that of three commercial nuclear power plants out of the more than 450 worldwide. Since research reactors are rarely operated at the 90% full power uptime typical of commercial power plants, even this comparison overstates the size of the world research reactor spent fuel inventory. 
Security is another crucial challenge area where the range of reactor locations and fuel types creates a host of unique conditions.  In the late 1970s the Reduced Enrichment for Research and Test Reactors (RERTR) program was launched with the objective of exchanging HEU fuel with LEU enriched to below 20%.  This successful program and related international initiatives have largely succeeded in removing HEU from the research reactor fleet. Even so, any viable spent research reactor management strategy must provide robust physical security as well as material control and accounting (as defined in the IAEA Nuclear Material Accounting Handbook, http://www-pub.iaea.org/MTCD/publications/PDF/svs_015_web.pdf).

Presently many countries lack an effective long term policy for managing the back end of the research reactor nuclear fuel cycle. A methodical, thorough review of policy and technology options for RRSF back end management is needed. The review should focus on matching options to available skill sets, resource levels and other country-specific factors. It should be especially sensitive to the unique position of countries that are building, planning to build, or have recently completed their first or only research reactor.

The importance of the RRSF back end challenge has been highlighted in past IAEA-sponsored reports and workshops. For instance, a 2004-2006 study addressed spent fuel management options for research reactors in Latin America (Spent fuel management options for research reactors in Latin America, TECDOC 1508, 2006). A 2006 workshop (Return of Research Reactor Spent Fuel to the Country of Origin: Requirements for Technical and Administrative Preparations and National Experiences, TECDOC 1593, 2008) surveyed national perspectives on one RRSF back end option, take-back to country of origin, specifically the USA. In 2009, the IAEA published a document which is an extended summary and account of the experience obtained from the completion of international projects on return of spent nuclear fuel to the Russian Federation from research reactors in Uzbekistan, Czech Republic, Latvia, Bulgaria, and Hungary (Experience of Shipping Russian-origin Research Reactor Spent Fuel to the Russian Federation, TECDOC 1632, 2009). These resources provide an excellent jumping-off point for informing a dialogue with stakeholder nations.

Nuclear Component


This CRP will focus on technical aspects and quantification of options for managing the back end of the spent fuel from research reactors which are nuclear by their very nature.

CRP Overall Objectives


This CRP will include Member States who are responsible for the management of research reactor spent fuel as well as those who are currently building and planning new research reactors. The overall objective of this CRP is to define, characterize and disseminate a range of long-term strategies for managing the back end of the research reactor nuclear fuel cycle. The technologies comprising the strategies will focus on short- and long -term storage and ultimate disposal including both back-end strategies of either prior spent fuel reprocessing or direct spent fuel disposal. A publication will be issued to ensure outreach of CRP findings.
It is important to recognize that economic and human resources, existing infrastructure and geography will play key roles in defining the strategies that make the most sense for each country. For that reason, this CRP will emphasize concerns specific to countries that do not possess large commercial nuclear energy infrastructures. The key product of this work will assess RRSF storage and ultimate disposal taking into account safety and security requirements, technologies and human and economic resource requirements with respect to the constraints faced by these countries.

Specific research objectives


The research objectives of the CRP are tied to defining the challenge (RRSF inventories, types and characteristics, possible ways for treatment and conditioning of the spent fuel, identification of radioactive waste management tasks required) and quantifying the performance of each potential solution to the challenge. Research tasks will include: 1. Development of a standard approach to assess and analyse individual research reactor back end options. This methodology will consider inter alia, the quantity of spent fuel, the costs involved, identification and characterization of the broad classes of short and long term RRSF management strategies, for instance ongoing at-reactor or away-from-reactor storage, processing/separation, disposal, take-back by country of origin and other cooperative multinational options, and identification of the economic and human resources requirements associated with each technology and RRSF management strategy.
2. Quantitative assessment of the back end options for all participant countries in the CRP.
3. Quantitative comparison of national research reactor spent fuel management approaches versus regional or multinational arrangements for commercially available or otherwise agreed back-end services.
4. Examination of the value of research reactor coalitions in strengthening the negotiation power of the coalition as compared to a single research reactor (i.e. increase of the economic scale because of the larger number of spent fuel, reducing transportation costs, safety and security costs and in general overhead costs).
5. The results will be published as an IAEA Technical Report Series document and will be made available to the research reactor community.
The technical component of the CRP may involve predicting inventories of SNF using codes such as ORIGEN (https://rsicc.ornl.gov/codes/ccc/ccc3/ccc-371.html) or ALEPH, (http://publications.sckcen.be/dspace/bitstream/10038/231/1/aleph_1_1_2_rev0.pdf). Other modeling and simulation requirements may arise in connection with evaluating containers for storing RRSF, potential reprocessing technologies, disposal environments, or additional engineered systems.

Expected research outcomes


1.The results of the CRP would greatly contribute to the implementation of long term management strategies for RRSF in accordance with the unique constraints and conditions faced by the dozens of countries that possess research reactors, many without a corresponding nuclear energy programme.
2.Dissemination of the results of the CRP – key nuclear fuel cycle technologies enabling sustainable management of RRSF, including options and technologies for its reprocessing, storage and ultimate disposal – could be used by the research reactor community to improve the management of the back end of the research reactor nuclear fuel cycle at individual research reactors.

Expected research outputs


1. The main output will be an IAEA Technical Report Series to document the results of the CRP and to make available to the research reactor community.
2. A report for each participant country of the CRP presenting the back end strategies developed during the CRP for the management of the research reactor spent nuclear fuel. Every participant country will use the standard approach to develop the report.
3. A report comparing national research reactor spent nuclear fuel management options versus regional or multinational options including commercially available or otherwise agreed back-end services. The report will present the economic and human resources requirements associated with each option.
4. A report discussing the relevance of research reactor coalitions versus a single research reactor to reduce overhead costs involved in the management of the back end of the research reactor nuclear fuel cycle.

Timelines

  • Consultancy meeting (Vienna): 15 – 18 July 2014. Please find the Consultancy Meeting Summary.
  • First RCM (Vienna): late 2014 or early 2015
  • Second RCM: 2016
  • Draft report: 2016
  • Regional workshop (Africa or Middle East): 2017
  • Regional workshop: (Asia or Latin America): 2017
  • Third RCM (Vienna): 2018
  • Final report: 2018


Vietnam removes high enriched uranium research reactor fuel (Photo: Sandor Tozser / IAEA)