Monitoring of the fuel elements condition in a burnt fuel interim storage at the NPP SE-EBO

Cladding of fuel elements is the best way how to keep the fission products inside the fuel elements and keep the environment safe. Hence is really important to make this cladding that it will be resistant toward many influences, witch have negative effects on their damage. The cladding plays big role in safety operation, transportation and also in final deposition oaf burnt nuclear fuel. Therefore is the research of these materials so important. Cladding requirements:-small neutron absorption; - radiation, mechanical and chemical stability during transportation and also during his reside in reactor; - high thermal conductivity. There are many materials witch are used in reactors for cladding of fuel elements: - magnesium alloys (for metallic uranium fuel and gas cooled reactors); - zirconium alloys (for oxid uranium fuel, PWR, BWR, FBR); - stainless steel (for ceramic fuel, HTR, FBR with Na); - graphite (HTR, HTTR, GHTR, PBMR). The corrosion, hydriding, growth and creep performance of current Zirconium alloys does not permit the more aggressive operating and environmental conditions required to achieve higher duty and longer cycle. There are many systems for monitoring oaf fuel elements condition. The most used are: - Sipping in core ('during' operation); - Integral leaking test of fuel containers for transfer of fuel elements (C-30); - Sipping in pool, ANF Ultratest, Sipping test on IEA RI (during storage). In this paper is detection of leakages in a wet interim spent fuel storage described. A quick detector was found, it measures Cs134 and Cs137 (Authors)