IAEA/USA Interregional course on
Preparations to Ship Spent Nuclear Fuel (1997)

Experience on Wet Storage Spent Fuel Sipping
at IEA-R1 Brazilian Research Reactor

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IAEA/USA Interregional Training Course

Technical and Administrative Preparations Required for Shipment of Research Reactor Spent Fuel to its Country of Origin

13-24 January 1997
Argonne, IL

L.13.5

Experience on Wet Storage Spent Fuel Sipping
at IEA-R1 Brazilian Research Reactor

Paper Written by

J.A.Perrotta; L.A.A.Terremoto; C.A.Zeituni

and Presented by

Roberto Frajndlich

Divisão de Engenharia do Núcleo
Instituto de Pesquisas Energéticas e Nucleares
IPEN-CNEN/SP
Travessa R 400 - Cidade Universitária
São Paulo - SP - Brasil - 05598/900
* e.mail - [email protected]

ABSTRACT

IEA-R1 Research Reactor of Instituto de Pesquisas Energéticas e Nucleares (IPEN/CNEN-SP) is a pool type reactor of B&W design operating since 1957 at 2 MW of power. Irradiated fuels have been stored at the facility along the various years of operation. Nowadays there are 40 spent fuel assemblies at dry storage, 79 spent fuel assemblies at wet storage and 30 fuel assemblies in core. The oldest fuels are of USA origin, made with U-Al alloy both of LEU and HEU MTR fuel type. Many of these fuel assemblies present corrosion pits along lateral fuel plates. These pits have their origin by galvanic corrosion between fuel plate and stainless steel storage rack although the excellent pool water characteristic would inhibit this occurrence of corrosion. Radiological analysis of pool water have been indicating low activity of 137Cs. According to the decision to send back the old fuels to USA, sipping tests with spent fuel assemblies were performed in order to evaluate their 137Cs leaking rate, if any. This paper describes the procedure and methodology used to perform sipping test with the fuel assemblies at the storage pool, and presents the results obtained for the 137Cs sipping water activity for each fuel assembly. Discussion is made correlating corrosion pits to the activity values measured. A 137Cs leaking rate is determined which can be compared to the criteria established for canning spent fuel assemblies before shipment.