METHODOLOGICAL ASPECTS FOR NUMERICAL ANALYSIS …€¦ · METHODOLOGICAL ASPECTS FOR NUMERICAL ANALYSIS OF LID SYSTEMS FOR SNF AND HLW TRANSPORT PACKAGES Konrad Linnemann, Viktor

METHODOLOGICAL ASPECTS FOR NUMERICAL ANALYSIS OF LID SYSTEMS FOR SNF AND HLW

TRANSPORT PACKAGES

Konrad Linnemann, Viktor Ballheimer Jens Sterthaus

Frank Wille

BAM, Germany

Package Analysis: Structural Analysis Special Topics

METHODOLOGICAL ASPECTS FOR NUMERICAL ANALYSIS OF LID SYSTEMS FOR SNF AND HLW

TRANSPORT PACKAGES

Konrad Linnemann Viktor Ballheimer Jens Sterthaus

Frank Wille

BAM Federal Institute for Materials Research and Testing Berlin, Germany

PATRAM 2013 3 BAM / 3.3 / Linnemann

Outline

General aspects about Type B(U) lid systems

Numerical assessment of lid systems according to guideline

BAM-GGR 012

Finite element modeling strategy

Numerical Solutions • 9 m vertical drop test • 9 m lateral drop test

Concluding Remarks


General Aspects

protective plate

pressure sensor

secondary lid

primary lid

basket

trunnion cask cooling fin neutron moderator

Transport and Interim storage Casks for Spent Fuel and HAW 2 bolted lids (primary and secondary)

as part of the containment system Lid system as barrier

• Lid + bolts • Inner metallic gasket

(aluminum or silver) • Outer elastomeric gasket • Orifice Lids


General Aspects / Assessment of lid systems

Activity release criteria specified by IAEA regulations SSR-6 under routine, normal and accident condition of transport (RCT, NCT, ACT)

BAM-GGR012 Guideline for numerical assessment of bolted lid and trunnion systems

Drop tests Gasket performance tests Numerical analyses

Combined methods of assessment

Assessment of lid system by ensuring Integrity Leak tightness


Numerical Assessment According to BAM-GGR012

General criterion for lid • Assessment with local stresses:

e.g. to exclude local plastic deformations

• Brittle fracture assessment: BAM-GGR 007, FKM-Guideline

Displacements / deformations in gasket area (e.g. opening, sliding) • Assessment of sealing function based

on results of drop tests and gasket performance tests

• Assume minimum pretension for bolts

Bolt assessment • Nominal stress concept • Assume pretension range for bolts


Numerical Assessment According to BAM-GGR012

Load steps

Loading (RCT, NCT, ACT)

Unloading (Assessment openings gasket)

Assembly (Tightening of bolts)

Criteria for bolts BAM-GGR012

tens

ile

equi

vale

nt

PATRAM 2013 8/18 BAM / 3.3 / Linnemann

Dynamic FEA (explicit time integration)

Advantages Modeling of whole packages Realistic application of loads Disadvantages Material modeling e.g. of wooden

shock absorbers Time increment’s dependency on

characteristic element length

Modeling Strategy / Explicit vs. Implicit

Quasi-static FEA (implicit time integration)

Advantages Detailed stress assessment

Disadvantages Constant and homogeneous

acceleration field Requires extra load factors for

considering dynamic effects

Mechanical System Dynamic problem, multiple mass effects Accelerations and thermal loads (NCT, ACT) + interior pressure Contact problem: Lid cask body + bolt head lid Tightening of bolts minimum and maximum pretension


Modeling Strategy / Lid Systems

Quasi-static implicit analysis with homogeneous acceleration field Extra load factors considering internal impacts Elastic material model for bolt assessment Elastic-plastic material for assessment of deformations in gasket area

9m lateral drop test thermal test 9m vertical drop test

Reduction of modeled components


Modeling Strategy / Numerical Evaluation

Calculation of according to VDI 2230

section Evaluation of axial forces N and bending moments M

along clamping length

For each section: Integration of nodal forces

Calculation of nominal stresses

BAM-GGR012: Nominal stress concept for bolts

(tensile) (bending) (equivalent)


Calculation Results / 9 m Vertical Drop

FE-Model Quasi-static analysis of primary lid system considering 9 m vertical

drop test Symmetry circular sector with 1 bolt of strength grade 10.9 Incrementally increased homogeneous acceleration until 100 g Reaction forces of metallic gasket as constant surface loads

PATRAM 2013 12/18 BAM / 3.3 / Linnemann


s



Evolution of bolt stresses

Sensitivity of bolt stresses with respect to requirements

69 (decisive load case)



Low penetrations of contact surfaces, but influence on remanent values Cumulative assessment of irreversible displacements for the gasket groove

under consideration of all ACT tests (especially 30 min. fire test)

Evolution of maximum opening during loading and unloading


Calculation Results / Dynamic Analysis

FE-Model Dynamic model (LS-DYNA) Initial velocity and pressure impulse p(t) No multiple mass effect Comparison with quasi-static solution


Calculation Results / Dynamic Analysis

Bolt stresses relative to static solution (tensile and bending)

Dynamic amplification factor 1.9 for assumed load


Calculation Results / 9 m Lateral Drop

Quasi-static implicit analysis for assessing 9 m lateral drop Half-model of primary lid system based on symmetry Incrementally increased acceleration field until 180 g 22.5 bolts of strength grade 10.9

180 g


Calculation Results / 9 m Lateral Drop

Evolution of bolt stresses

A

B C

D

A, B: Begin of sliding between lid and cask

C, D: Begin of sliding between bolt head and lid


Concluding Remarks

Modeling strategies • Quasi-static (implicit) and dynamic (explicit) FEA • Aspects of implicit modeling

Assessment methods for lid systems of Type B(U) packages • BAM GGR012 Guideline • Criteria of bolts

Presented Solutions • 9 m vertical and lateral drop • Bolt assessment based on nominal stress concept • Displacements in gasket area • Sensitivity of assessment criteria with respect to applied load • Evaluation of dynamic amplification with a simplified dynamic

model for the 9 m vertical drop

Documents

METHODOLOGICAL ASPECTS FOR NUMERICAL ANALYSIS …€¦ · METHODOLOGICAL ASPECTS FOR NUMERICAL ANALYSIS OF LID SYSTEMS FOR SNF AND HLW TRANSPORT PACKAGES Konrad Linnemann, Viktor