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New Nuclear Fuel Cycle. Fuel Reprocessing

#3900


Adv-ORIENT Cycle – a New Approach to Spent Nuclear Fuel Reprocessing. Sorption Behavior of Elements at Basic Stages of Spent Nuclear Fuel Reprocessing Flowsheet

Tech Area / Field

  • CHE-RAD/Photo and Radiation Chemistry/Chemistry
  • ENV-RWT/Radioactive Waste Treatment/Environment

Status
3 Approved without Funding

Registration date
07.10.2008

Leading Institute
Khlopin Radium Institute, Russia, St Petersburg

Collaborators

  • Tokyo Institute of Technology, Japan, Tokyo\nJapan Atomic Energy Agency, Japan, Ibaraki

Project summary

In the traditional flowsheets of spent nuclear fuel (SNF) reprocessing of power reactors, which are based on extraction processes, the base products are uranium and plutonium. Almost full amount of other SNF components (including long-lived radio nuclides) is directed to storage as wastes of fuel reprocessing. Wastes of reprocessing are characterized by their state (liquid, solid, water solutions, organic solutions etc.), volume, and specific radio-activity (high, medium and law active). The storage of radioactive wastes creates the certain ecological burden on an environment. The influence of this burden on an environment is definitely negative and in long-term prospect unpredictable.

Development by the Japanese researchers of the multifunctional flowsheet of reprocessing of fast neutron reactors (FR) SNF within the framework of the created new nuclear fuel cycle Adv-ORIENT (Advanced Optimization by Recycling Instructive Elements) is a new approach to the decision of the problem of a storage of SNF reprocessing wastes. The main features of the flowsheet being in development are:

  • Realization of the basic operations of recovery and separation (steps of the flowsheet) by an ion exchange method;
  • Realization of most operations using HCl media or in combination with operations in HNO3 media;
  • Applied use of most amount of radionuclides (excluding long-lived ones);
  • Direction of long-lived radionuclides to transmutation.

Use of ion-exchange method in the main operations of the flowsheet excludes formation of liquid organic wastes. Applied use of all amount of 137Cs, Sr, Ru, Rh, Pd and part of Tc, transmutation of the radiological hazardous isotopes of Am and Cm, long-lived 99Tc and 135Cs will considerably simplify the problems of immobilization and utilization of liquid wastes.

Key operations of the new flowsheet are the steps of:

  1. Recovery of platinum group metals (PGM) and some other fission products (FP);
  2. Group separation of FP and lanthanides (Ln); minor actinides (MA); U, Np, Pu fraction;
  3. Am-Cm separation.

The ion-exchange resin with tertiary pyridine groups synthesized by the experts of the Tokyo Institute of Technology (TITECH) is used in these operations. During synthesis the resin is imbedded in silica gel that increases its mechanical durability and radiation resistance.

The development of the flowsheet passes the certain stages. Up to now the successful tests of the main steps of the flowsheet were carried out at the research centre in O-arai. In these tests HCl solutions of FR SNF were used, but due to certain limitations concerning amounts of radioactive materials, they contained radionuclides only in trace amounts. Carried out experiments (1 and 2 steps) have shown ability of resin to ensure separation of required basic elements or groups of elements with high factors of separation. However, the analytical maintenance of experiments has not allowed obtaining the data on sorption behavior of β radiating nuclides and some stable isotopes. The occupation of the process equipment of the centre makes realization of experiments with weight amounts of FR SNF impossible in the near future. Established before connections between the Japan Atomic Energy Agency, Tokyo Institute of Technology and V.G. Khlopin Radium Institute allow solving this problem. The needed experiments can be carried out in Gatchina unit of Radium Institute, which has hot cells allowing working with hundreds of grams of SNF and analytical equipment that enables to carry out the analysis of practically each element contained in spent fuel.

In view of the large financial expenses required on purchase and transportation of FR fuel, the following content of works is offered. The necessary amount of RBMK SNF is dissolved in nitric acid, the solution is evaporated to dryness and the dry rest is dissolved in hydrochloric acid. Then the required elements in the appropriate chemical form for obtaining the solution simulating content of FR fuel of given burn-out and cooling are added into this solution.

Operations of an ion-exchange in HCl solutions will be further carried out. In a basis of researched ion-exchange operations the technique of elution chromatography lays. It consists in loading a chromatographic column with a portion of an initial solution and further elution of the obtained zone by solutions of various contents with gaining fractions of separate or groups of elements. The analytical control consists in obtaining the chromatogram of this process on the basis of which separation and purification factors will be calculated and conclusions about efficiency of the obtained separation will be made. During the tests anti-radiolysis, hydrolysis properties of the resin will be also evaluated using preliminary irradiated resin in contact with real radioactive solutions.

Thus, the aim of this Project is to create novel and practicable reprocessing flowsheet of highly environmental-friendly, non-proliferatively kind. This aim is achieved by gaining new experimental data about sorption behavior of gram amounts of the elements contained in FR SNF, at realization of operations of their recovery and separation on resin with tertiary pyridine groups in HCl solutions

The successful performance of the Project will be promoted by wide experience as of Radium Institute as a whole and concrete participants of the Project in the field of SNF reprocessing, including ion-exchange method.

The offered Project relates to a category of applied research. The obtained results will serve as a basis for further development of key ion-exchange operations of the flowsheet of FR SNF reprocessing in the frame of Adv-ORIENT cycle.

The presented Project meets the realization of the ISTC goals to develop technologies in the field of protection of an environment and anti-nuclear proliferation and gives an opportunity to the participants connected to the weapon for activity in peace area.

Scope of activities given in the Project is to be carried out during 18 months,

Collaborators of the Project are the Japan Atomic Energy Agency (JAEA), O-arai Research and Development Center and the Tokyo Institute of Technology (Tokyo TEC), Research Laboratory for Nuclear Reactors.

Tasks of collaborators are advices on modes of ion-exchange operations, control under preparation and realization of experiments. The obtained results will be discussed at joint seminars by the representatives of the parties. The joint publications based on the results of work will be prepared.


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