Behavior of Metallic Seals in CASTOR Casks under Normal and Accident Conditions of Transport

Transcription

1 Behavior of Metallic Seals in CASTOR Casks under Normal and Accident Conditions of Transport Qualification Requirements Sven Shb Schubert Frank kkoch Ulrich Probst BAM, Federal Institute for Materials Research and Testing, D Berlin, Germany Hans Peter Pt Winkler GNS Gesellschaft für Nuklear Service mbh, D Essen, Germany PATRAM 2007, Miami, Florida, USA Sven Schubert PATRAM

2 Introduction and content 1. Double Jacket Metal Seal Configuration and Installation 2. Required Proof for Qualification of Metallic Seals Seal qualification 3. Conclusions Tightness under axial mechanical loading Tightness under radial mechanical lloading Influence of Particles on tightness Chemical resistance and corrosion Sven Schubert PATRAM

3 Double Jacket Metal Seal Configuration and Installation Inner Jacket Stainless Steel, , (GS) Outer Jacket Aluminium, Al 99,5 Silver, Ag 99,99 Helical spring Nimonic 90, (GS) Configuration Closure Cask Body Primary Lid Installation Requirement on the leak tightness if used for transport and storage casks Q He/St < 10 8 Pa m 3 / s Sven Schubert PATRAM

4 Methods to demonstrate the ability of containment system to meet the leakage rate criteria under mechanical loading Drop tests t on full scale l casks or reduced scale models within a drop test program of approved cask design type (the reliability has to be assured by statistical confirmation) Component test program with simulation of lid and seal displacements and involvement of specific drop tests Sven Schubert PATRAM

5 Further parameters to consider for seal qualification Conditions during operation Short term effects Long term effects Corrosion behavior Influence of particles in the seal contact area on tightness Thermal behavior Thermal behavior Corrosion behavior of both jackets Influence of radiation to the material properties Effects of radiolysis from enclosed water on sealing integrity Sven Schubert PATRAM

6 Main issues for a qualification program for double jacket metal seals Material specification Load Deformation Curve Df (one time compression) Tightness under axial loading (repeated compressions) Tightness under radial loading (flange/seal displacement) Influence of maximum and minimum temperatures under NCT and ACT Particle test Corrosion Long term performance Sven Schubert PATRAM

7 Tightness under axial mechanical loading One time compression E-05 Y 2 Load N / mm Y 0 load leakage rate 1.0 E E-07 L E-08 Leaka age rate Pa m3/s E-09 Y E Deformation mm Example of a Load Deformation Curve of a Double Jacket Seal with outer jacket of Silver including Measurement of the Leakage Rate r u Example of a Test Set up for axial compression Standard test for quality assurance during fabrication Sven Schubert PATRAM

8 Tightness under axial mechanical loading Repeated compression Results from vertical drop tests of casks onto the lid or bottom Component test simulates short term axial lid coming off followed by complete closing After repeated compression standard helium leakage rate has to be measured periodically for a minimum 7 days to get information about long term behavior. Repeated compression has to be distinguish between Compression without seal displacement because of sufficient high clamping load (around Y 1 ) Compression including seal displacement to simulate a complete seal resilience and, hence, repositioning Sven Schubert PATRAM

9 Tightness under axial mechanical loading GNS test results for repeated compressions Compression without ih seal Compression including seal displacement displacement For seals with aluminium and silver outer jacket Achievement of Q He/St Pa m 3 /s up to five times compression and load relieve. The standard helium leakagerates measured directly after twice performed compression were in the range to meet the requirements of IAEA TS R 1 concerning the loss of radioactive contents. Sven Schubert PATRAM

10 Tightness under radial mechanical loading Results from horizontal cask drop test when the lid is displaced into radial direction Value of lid displacement derive from mechanical proof for NCT and ACT in SAR Before relieving of radial mechanical loading, maximum displacement has to be kept 30 min After relieving the standard helium leakagerate has to be measured periodically for a minimum 20 days to get information about long term behavior. Test Set Up for Simulation of a Radial Displacement of the Lid Flange Sven Schubert PATRAM

11 Tightness under radial mechanical loading GNS test results for radial lid displacement For seals with silver outer jacket For seals with aluminium outer jacket No significant increase of Standard helium leakage rate leakage rate initial standard heliumleakage rate (Q He/St and initial value about a one order increased compared to the lower) after displacement. of magnitude maximum 30 to 40 minutes after radial displacement. However the initial value could be achieved with an extended test period. Sven Schubert PATRAM

12 Influence of particles in the contact area on tightness Arrangement of Corundum Grains on Seal/Flange Contact Area Aluminium Seal with Pressed in Grains on Seal/Flange Contact Area GNS test results For seals with aluminium and silver outer jacket Smaller particles had no influence on the leakage rate Grains were completely enclosed in the outer jacket material Sven Schubert PATRAM

13 Chemical resistance and corrosion Results from cask loading under water BAM requires proof regarding the water resistance of each sealing material and corrosion behavior from contact with different materials Considering boron content in the water and possible impurities of ions from chloride, iron and copper Solution 1 2 Boron >2500ppm >2500 ppm Chloride no yes Copper no yes Ferreous content no yes Soluted in Deionat Deionat ph value Qualitative Composition of Corrosion Test Fluids Sven Schubert PATRAM

14 Conclusions BAM requires proof of compliance of leakage rate criteria under mechanical loadings from RCT, NCT and ACT for use of double jacket metal seals in transport casks. Since there is only a small number of drop tests with full scale casks or reduced scale models additional tests are necessary to show the statistically confirmed ability of the containment system to meet the leakage ratecriterion.therefore, BAM requires a qualificationprogram prepared by the applicant containing all relevant mechanical, corrosion and particle tests. Based on the results of all tests, the applicant has to determine seal design values for the standard helium leakage rate in relation to effects on containment systems under routine, normal and accident conditions of transport, direction of mechanical loading and duration of the leakage rate measurement. Sven Schubert PATRAM

15 Behavior of Metallic Seals in CASTOR Casks under Normal and Accident Conditions of Transport Qualification Requirements Sven Shb Schubert Frank kkoch Ulrich Probst BAM, Federal Institute for Materials Research and Testing, D Berlin, Germany Hans Peter Pt Winkler GNS Gesellschaft für Nuklear Service mbh, D Essen, Germany Thank you for your attention. Sven Schubert PATRAM