Sloshing Behaviors in Liquid Metal Reactors

SUMMARY

I. Project Title

Sloshing Behaviors in Liquid Metal Reactors

II. Purpose and Importance on the Research

Earthquake induced hydrodynamic pressure and sloshing wave height

of a free surface in a fluid-structure system will be important design

parameters. Especially, for the fluid-structure system containing a large

amount of liquid such as a liquid metal fast breeder reactor (LMFBR),

those parameters may threaten its safety. Therefore, when the seismic

response of the LMFBR is underestimated, the reactor vessel may be

damaged or failed significantly due to the buckling and the sloshing

impact.

It is very difficult to predict sloshing response in the LMFBR which

contains many internal components, since the sloshing response of a

coolant depends not only upon the frequency contents of input ground

motion, but also upon the configuration of reactor vessel and internal

components, arrangement of internal components, and excitation direction of

ground motion. Therefore, clear understanding of sloshing in the reactor

vessel and development of proper technologies to predict sloshing response

are necessary to establish the safety of the LMFBR against earthquakes.

The purpose of this report is to review sloshing behaviors in the

LMFBR for the clear understanding of sloshing characteristics and to

- vi -

propose some interesting topics to be studied in future.

III. Scope and Contents of the Research

This report investigates sloshing behaviors in a pool type and a top-

entry loop type LMFBRs, and also investigates the effect of a base-

isolation system on the sloshing response in the pool type reactor. The

sloshing impact pressure on the roof of the pool type LMFBR is discussed.

It may be impossible to obtain the sloshing response of the LMFBR by

analytical method since it contains many internal components. Even if one

use some numerical methods such as the boundary element method and

finite element method, there will be some problems in the modelling and

analysis because three-dimensional nonlinear sloshing analysis has to be

carried out. Accordingly, some experimental studies were performed to

understand sloshing behaviors and verify numerical methods in the

LMFBR. The outline of the experiments including test model, test

apparatus, and test conditions are addressed in this report.

IV. Result of the Research and Suggestion for the Application

This report reviews sloshing behaviors in the LMFBR and proposes

some noticeable topics to be studied in future.

The sloshing behaviors in the LMFBR can be summarized as follows:

- Sloshing behavior varies significantly according to the presence of the

internal components and their arrangement, and sloshing amplitude

depends mainly on the frequency content characteristics of the ground

motion.

- vn -

- Sloshing natural frequencies and sloshing wave height decrease and

damping factors increase in the presence of internal components.

The effect of the multi-surface connection on the sloshing

characteristics is low in the top entry loop type LMFBR. The

damping ratio increases and the higher sloshing modes disappear

under the effect of the in-vessel forced flow.

- Sloshing response may increase significantly under the ground motion

dominated by low frequency in the base-isolated reactors.

- The largest sloshing impact pressure usually appear when the first

wave collides with the roof.

- When the fluid-structure system contains internal bodies and the free

surface collides with the roof, a nonlinear sloshing analysis should be

carried out.

The topics to be studied in future are proposed as follows:

- Sloshing analysis techniques for the complex fluid-structure systems

- Nonlinear sloshing analysis methods

- Effect of the higher sloshing modes on the response of internal

components

- Effect of nonlinear fluid on the sloshing behavior

- Devices for reducing sloshing wave height

- Optimum base-isolation system to minimize sloshing response

- Fluid-structure interaction considering the flexibility of the reactor

vessel and internal components

vm -

BIBLIOGRAPHIC INFORMATION SHEET

Performing Org.Report No.

Sponsoring Org.Report No.

Standard Report No. INIS Subject Code

KAERI/TR-1039/98

Title / Subtitle Sloshing Behaviors in Liquid Metal Reactors

Project Manager(or Main Author)and Department

Choun, Young Sun (Integrated Safety Assessment Team)

Researcher andDepartment

Yoo, Bong (KALIMER Mechanical Structure Design)Lee, Jae Han (KALIMER Mechanical Structure Design)

PublicationPlace

Taejeon Publisher KAERIPublication

Date1998. 4.

Page 78 p. 111. & Tab. Yes( v ), No ( ) Size 26 cm.

Note

ClassifiedOpen( v ), Restricted(

Class DocumentReport Type Technical Report

Sponsoring Org. Contract No.

Abstract (15-20 Lines)

It is very difficult to predict sloshing response in the LMFBR whichcontains many internal components, since the sloshing response of acoolant depends not only upon the frequency contents of input groundmotion, but also upon the configuration of reactor vessel and internalcomponents, arrangement of internal components, and excitation direction ofground motion. Therefore, clear understanding of sloshing in the reactorvessel and development of proper technologies to predict sloshing responseare necessary to establish the safety of the LMFBR against earthquakes.

The purpose of this report is to review sloshing behaviors in theLMFBR for the clear understanding of sloshing characteristics and topropose some interesting topics to be studied in future.

Subject Keywords(About 10 words)

LMFBR, Sloshing, Pool-Type, Top-Entry Loop Type,Isolation System, Impact Pressure, HydrodynamicPressure, Vibration Test, Test Model