Fast Reactors and Accelerator Driven Systems Knowledge Base

Working Materials of the Technical Working Group on Fast Reactors

Characterization and Management of Radioactive Sodium and Other Reactor Components as Input Data for the Decommissioning of Liquid Metal-cooled Fast Reactors

report nr.: TWGFR/110

A number of liquid metal cooled fast reactors (LMFRs) are in operation and, some have already been shut down; other reactors will reach the end of their design lifetime in a few years and become candidates for decommissioning. It is unfortunate that little consideration was devoted to decommissioning of reactors at the plant design and construction stage. It is with this focus that the Technical Working Group on Fast Reactors (TWGFR) recommended that the IAEA organize the exchange of information on LMFRs decommissioning technology. It was pointed out that the decommissioning of small sodium-cooled reactors has shown that there are two basic differences between thermal and fast reactors decommissioning: on the one side, the treatment and disposal of radioactive sodium coolant, and on the other side, the management of reactor components, for which the structural materials are activated in depth by fast neutrons.

To this end, a Technical Committee Meeting on Sodium Removal and Disposal from LMFRs in Normal Operation and in the framework of Decommissioning (Aix-en-Provence, France, November 1997) and two Consultancies on Decommissioning of the Kazakh BN-350 LMFR (Vienna, Austria, October 1996; Obninsk, Russian Federation, February 1998) were convened by the IAEA. These Meetings brought together a group of experts from France, Russia, Kazakhstan, the UK, and the USA to exchange information on, and to review current technical knowledge and experience in the management of radioactive coolant and reactor components following closing of LMFRs, as well as their design features and operating experience relevant for decommissioning procedures.

The report provides general and detailed information on activation characteristics of the primary coolant; treatment and disposal of the spent sodium; removal of the residual sodium deposits and decontamination; the activation characteristics of the reactor components and the management of the latter. The recurring theme is finding solutions to the problems and difficulties associated with the management of radioactive sodium.

Contents

SUMMARY
REFERENCES
BIBLIOGRAPHY ON REACTOR DECOMMISSIONING

PART I . TECHNOLOGIES AND INPUT DATA FOR SODIUM AND REACTOR COMPONENTS MANAGEMENT AFTER SHUT DOWN OF THE BN-350 LMFR

1 . DESIGN AND OPERATIONAL FEATURES. RADIOLOGICAL CHARACTERISTICS OF THE REACTOR PLANT
2 . HANDLING OF SPENT FUEL ACCUMULATED DURING REACTOR OPERATION
3 . PURIFICATION AND UTILIZATION OF SPENT SODIUM COOLANT OF PRIMARY AND SECONDARY CIRCUITS
4 . REPROCESSING OF THE RADIOACTIVE SODIUM WASTE INTO SAFE CONDITION FOR DISPOSAL
5 . WASHING THE RESIDUAL SODIUM DEPOSITS AND DECONTAMINATION OF REACTOR CIRCUITS. EQUIPMENT AND STRUCTURAL MATERIALS
6 . RADIATION CONDITIONS IN THE PRIMARY CIRCUIT CELLS. ACTIVITY OF THE REACTOR BLOCK ELEMENTS
7 . THE BN-350 REACTOR DECOMMISSIONING PLANNING

PART II . ACTIVITIES ON LMFRs DECOMMISSIONING

8 . DECOMMISSIONING OF THE EXPERIMENTAL LIQUID METAL COOLED FAST REACTOR RAPSODIE
9 . DECOMMISSIONING OF THE UK PROTOTYPE REACTOR (PFR)
11 . DECOMMISSIONING OF THE EBR-11 COMPLEX
12 . KNK DECOMMISSIONING

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