NUREG/CR-4977

EGG-2505

Vol.---1

SHAG Test Series -

I

- Seismic Research on an Aged United States Gate Valve

and on a Piping System in the Decommissioned

Heissdampfreaktor (HDR): Summary

Prepared by R. Steele, Jr., J. G. Arendts

Idaho National Engineering Laboratory

EG&G Idaho, Inc

Prepared for

U.S. Nuclear Regulatory

Commission
AVAILABILITY NOTICE

Availability of Reference Materials Cited in NRC Publications

Most documents cited in NRC publications will be available from one of the following sources:

1. The NRC Public Document Room, 2120 L Street, NW, Lower Level, Washington. DC 20555

2. The Superintendent of Documents, U.S. Government Printing Office. P.O. Box 37082, Washington,

DC 20013-7082

3. The National Technical Information Service. Springfield, VA 22161

Although the listing that follows represents the majority of documents cited In NRC publications, It is not

Intended to be exhaustive.

Referenced documents available for Inspection and copying for a fee from the NRC Public Document Room

include NRC correspondence and Internal NRC memoranda; NRC Office of Inspection and Enforcement

bulletins, circulars, information notices, inspection and Investigation notices; Ucensee Event Reports; vendor reports and correspondence; Commission papers; and applicant and licensee documents and correspondence.

The following documents in the NUREG series are available for purchase from the GPO Sales Program:

formal NRC staff and contractor reports, NRC-sponsored conference proceedings, and NRC booklets and

brochures. Also available are Regulatory Guides, NRC regulations In the Code of Federal Regulations, and

Nuclear Regulatory Commission Issuances.

Documents available from the National Technical Information Service include NUREG series reports and

technical reports prepared by other federal agencies and reports prepared by the Atomic Energy Commisslon, forerunner agency to-the Nuclear Regulatory Commission.

Documents available from public and special technical libraries include all open literature Items, such as

books, journal and periodical articles, and transactions. Federal Register notices, federal and state legislation, and congressional reports can usually be obtained from these libraries.

Documents such as theses, dissertations, foreign reports and translations, and non-NRC conference proceedings are available for purchase from the organization sponsoring the publication cited.

Single copies of NRC draft reports are available free, to the extent of supply, upon written request to the

Office of Information Resources Management, Distritution Section, U.S. Nuclear Regulatory Commission,

Washington, DC 20555.

Copies of Industry codes and standards used In a substantive manner In the NRC regulatory process are

maintained at the NRC Library, 7920 Norfolk Avenue, Bethesda, Maryland, and are available there for reference use by the pubic. Codes and standards are usually copyrighted and may be purchased from the

originating organization or, If they are American National Standards, from the American National Standards

Institute, 1430 Broadway, New York, NY 10018.

DISCLAIMER NOTICE

This report was prepared as an account of work sponsored by an agency of the United States Government.

Neitherthe United States Govemrnment norany agency thereof, orany of theiremployees, makes any warranty,

expresed or implied, or assumes any legal liability of responsibility for any third party's use, or the results of

such use, of any information, apparatus, product or process disclosed in this report, or represents that its use

by such third party would not infringe privately owned rights.
NUREG/CR-4977

EGG-2505

Vol. 1

R1

SHAG Test Series

Seismic Research on an Aged United States Gate Valve

and on a Piping System in the Decommissioned

Heissdampfreaktor (HDR): Summary

Manuscript Completed: July 1989

Date Published: August 1989

Prepared by

R. Steele, Jr., J. G. Arendts

Idaho National Engineering Laboratory

Managed by the U.S. Department of Energy

EG&G Idaho, Inc.

P.O. Box 1625

Idaho Falls, ID 83415

Prepared for

Division of Engineering

Office of Nuclear Regulatory Research

U.S. Nuclear Regulatory Commission

Washington, DC 20555

NRC FIN A6322

Under DOE Contract No. DE-AC07-761D01570
ABSTRACT

The Idaho National Engineering Laboratory (INEL) participated in an internationally

sponsored seismic research program conducted at a decommissioned experimental reactor

facility, the Heissdampfreaktor (HDR), located in the Federal Republic of Germany (FRG).

The research program included the study of the effects of excitation, produced during a

simulated seismic event, on (a) the operability and integrity of a naturally aged 8-in. motoroperated gate valve installed in the Versuchskreislauf (VKL), an existing piping system

in the HDR, (b)'the dynamic response of the VKL and the operability of snubbers and

(c) the dynamic responses of various piping support systems installed on the VKL. The

INEL work, sponsored by the U.S. Nuclear Regulatory Commission (USNRC), contributes

to earthquake investigations being conducted by the Kernforschungszentrum Karlsruhe

(KfK) and is part of the general HDR Safety Program performed in behalf of the FRG,

Federal Ministry for Research and Technology. This report presents the results of the

KfK-designated SHAG (Shakergebiude) test series; these are the first in situ experiments

involving an actual nuclear power plant and a full scale piping system under simulated

seismic loading.

INEL modified the VKL by installing a mid-life gate valve from a U.S. nuclear power

plant and by designing and installing a piping support system typical of U.S. commercial

design. Six other piping support systems of varying flexibility, from stiff to flexible, were

also installed at various times during the experiments. Valve loadings, in addition to the

seismic excitation, included internal hydraulic pressure, flow, andI drng ne 2

sriesf

experiments, elevated temperature.

Building- response m terms of zero period accelerations (ZPA) reached 0.3 g and exceeded

building design limits. The VKL response averaged over 1 g, with amplification at the

valve exceeding 3 g. One manufacturer's snubbers experienced ASME Code Level C

loadings. The valve response to dynamic motion showed unexpected amplification and

frequency content. Also, the valve motor operator developed a functional problem. Near

~~~~~~~~~~~~~clsn ai led *beendof cosig he ccle ale te mtorstaledwhn te cosg orclue switch ~faild

to open.

In all, twenty-five representative seismic experiments were conducted on the gate valve

and seven piping support configurations. Results of the testing will contribute to the technical

basis used for support and development of equipment qualification standards and procedures

sponsored by the NRC.

FIN No. A6322-u cation of Mechanical and Dynamic

(Including Seismic) Qualification of Mechanical and

Electrical Equipment Program (EDQP)

ii
SUMMARY

During the summer of 1986, the Idaho National

Engineering Laboratory (INEL), under contract with

the United States Nuclear Regulatory Commission

(USNRC), participated with the Kernforschungszentrum Karlsruhe (KfK), the Argonne National Laboratory (ANL), Staatliche Materialprfifungsanstalt (MPA),

Kraftwerk Union (KWU), and the Electrical Power

Research Institute (EPRI) in the KfK-designated SHAG

(Shakergebdude) test series at the Heissdampfreaktor

(HDR), a decommissioned experimental reactor facility

located in the Federal Republic of Germany (FRG).

This seismic research program consisted of a series

of tests to evaluate the structural response, thermalhydraulic performance, and fracture mechanics

behavior of the HDR and the components and systems

within the facility during simulated seismic excitation.

Specifically, the INEL investigated the operability

of the piping supports and an 8-in. gate valve and

assumed responsibility for the instrumentation and data

collection of the portion of the testing associated with

the Versuchskreislauf (VKL), a piping system located

in the HDR. Our investigation included (a) monitoring the operability, integrity, and response characteristics of the mid-life gate valve during a series of

simulated seismic events, (b) monitoring the operability

of typical nuclear industry snubbers in the in situ environment, (c) providing data for the EPRI snubber

replacement devices, and (d) recording the piping

system response data for use by ANL to verify the

SMACS (Seismic Methodology Analysis Chain with

Statistics) computer code.

The experimenters mounted a large, collapsing twinarm rotary mass coastdown shaker on the operating

floor (30-m level) of the HDR reactor building to

generate and transmit mechanical energy to the building. Force and motion were transmitted from the

building floors and internal structures to the piping

systems and components in the building.

The USNRC provided an aged 8-in. gate valve from

the decommissioned Shippingport Atomic Power

Station. The valve was refurbished, instrumented, and

tested to the applicable sections of ASME/ANSI

Standard B16.41 for installation in the HDR.

We performed a typical U.S. seismic analysis of the

existing VKL at the HDR. The results of this analysis

formed the basis for the piping system design modifications. The modifications consisted of installing the

refurbished gate valve and installing snubbers and struts

to set up a dynamic piping support system typical of

U.S. stiff nuclear piping support systems; subsequent

modification during the SHAG test series allowed us

to test six additional piping support systems. INEL

enhanced the VKL instrumentation system by installing 103 instruments to measure acceleration, strain,

displacement, force, temperature, pressure, valve stem

position, valve operator motor current and voltage, and

valve differential pressure. The VKL is constructed of

stainless steel (approximately equivalent to U.S.

Type 347) in four pipe sizes (equivalent to 10, 8, 5,

and 4 in.). The system is located between the 18- and

24-m elevations in the HDR facility. The piping system

internal fluid is electrically heated, and the system is

capable of operating at Pressurized Water Reactor

(PWR) secondary or Boiling Water Reactor (BWR)

primary pressure/temperature. A maximum differential pressure of 385 psid was achieved across the valve.

Twenty-five individual coastdown tests were performed with initial shaker starting frequencies, at the

beginning of coastdown, of 1.6 to 8 Hz. Only five of

the seven support systems were installed for the 6- and

4.5-Hz tests, and only the most flexible support system

was installed for the 1.6-Hz tests. Internal piping fluid

temperatures included both ambient (25 to 40'C) and

~eleae 0 )tmperatures. Tests were conducted

with and without hydraulic pressure in the piping

system, and with and without flow through the valve.

For each experiment, INEL and MPA collected the

data from the U.S. instruments installed to monitor the

response of the VKL and the U.S. gate valve, reciprocally shared data with KfK (who had also installed

instruments), and committed the data to permanent

records.

The response of the VKL was strongly influenced

by the motion of a large vessel called the Heissdampfumformer (HDU), to which part of the VKL was attached. HDU movement was greater than the dynamic

restraint anchorage movement and was the primary

forcing function influencing VKL behavior. Input to

the piping system exceeded typical U.S. East Coast safe

shutdown earthquakes (SSEs) and West Coast operational basis earthquakes (OBEs).

The starting frequencies important to valve and

piping response provided sufficient loading in the

piping system to determine the influence of piping support methodology on pipe and valve response. The

VKL response did not reach high levels of measured

strain in the piping system. However, it did reach levels

that loaded some of the installed snubbers to their

ASME Code Level C rating, and it provided sufficient

loading on the valve that in situ performance could be

assessed. The responses were also high enough to permit identification of distinct modes of response for the

various piping support systems and to allow assessment

of their performance.

I

iii
Pacific Scientific mechanical snubbers, the most

popular mechanical snubber used in nuclear power

plant applications, were used in the U.S. stiff piping

support system during most of the tests. These snubbers generally performed to the manufacturer's specifications. Four of the other piping support systems used

energy absorbing devices in place of the snubbers. The

ANCO system was stiffer than the snubbed U.S. stiff

system, and the EPRI Cloud, EPRI Bechtel, and GERB

of Berlin systems were all softer than the snubbed

system.

The naturally aged U.S. gate valve developed a

motor operator anomaly during the program. The

operator failed to open the closing torque switch on

closing, and the motor went into a stall. Posttest

investigations revealed that the motor operator torque

spring had taken a permanent set so that the motor

operator was not producing the rated torque for a given

torque switch setting (NRC Information Notice 89-43)_

Motor heating also reduced the operator's output. Later

analyses showed that external circuit resistance contributed significantly to the motor operator's poor performance at HDR (NRC-Information Notice 89-11. -

The analysis of the valve's dynamic response revealed amplification at frequencies other than those

determined from seismic bench tests performed for

valve qualification standards. The response above

33 Hz was not expected. Other full-scale, triaxially

excited valve system responses compared with HDR

results show similar results.

9I~ ~_7--

iv
ACKNOWLEDGMENTS

The efforts of many people and organizations were required to successfully conduct

the SHAG Test Series of the HDR Seismic Research Program. For the portion of the HDR

research reported herein, we wish to thank personnel from KfK PHDR, particularly Hr. Dr.

L. Malcher and Hr. Schrammel; from HDR, Herren H. Wenzel, L. Lohr, and R. Machad;

from MPA, Herren S. Hass and W. Ehling; and from the Fraunhofer Institut, Hr. Dr.

H. Steinhilber. USNRC provided early planning assistance by allowing Dr. Shafik Iskander

time to assist us; Drs. G. H. Weidenhamer and J. F. Costello, the onsite NRC Program

Managers, assisted us throughout the program. We also express gratitude to Dr. C. Kot

of ANL for his contributions to the program and his cooperation in this multinational,

multilaboratory effort, and to M. J. Russell of the INEL for his insights and assistance.

v
CONTENTS

ABSTRACT .................................... ................. ii

SUMMARY .................................... iii

ACKNOWLEDGMENTS ................................................................ v

NOMENCLATURE .................................................................... viii

1. INTRODUCTION ........................... .......................... I

1.1 Background . ................................................................... I

1.2 Objectives .................................................................... 1

1.3 Qualification Standards and Regulatory Guides ...................................... 2

2. TEST DESCRIPTION .............................................................. 3

2.1 The Heissdampfreaktor (HDR) ................................................... 3

2.2 Seismic Simulator .............................................................. 3

2.3 VKL Piping Support Systems .................................................... 3

2.4 Gate Valve . ................................................................... 10

2.5 Instrumentation ................................................................ 10

3. TEST RESULTS .................................................................... 13

3.1 Building Response ................ ............................................. 13

3.2 HDU Vessel Response .......................................................... 15

3.3 VKL Piping System Response ................................................... 18

3.4 Performance of Snubbers and Snubber Replacement Devices .......................... 20

3.4.1 Performance of Pacific Scientific Mechanical Snubbers ......................... 20

3.4.2 Performance of the Bergen Paterson Hydraulic Snubber ........................ 30

3.4.3 Performance of Snubber Replacement Devices ................................ 30

3.5 Comparison of Piping Support Systems ........ .............. ...................... 32

3.6 Valve and Motor Operator Response .............................................. 34

3.6.1 Structural Integrity of the Motor-Operated Valve .............................. 35

3.6.2 Valve Response ..................................................... 35

3.6.3 Performance of the Motor Operator ......................................... 35

3.6.4 Valve Dynamic Analysis .................................................. 44

vi
4. CONCLUSIONS ................................................................... 52

4.1 Building and Piping System Responses ............................................ 52

4.2 Snubber Responses ............................................................. 52

4.3 Snubber Replacement Devices Compared .......................................... 52

4.4 Valve Response . .............................................................. 53

4.5 Valve Dynamic Analysis ............. ........................................... 53

5. REFERENCES .................................................................... 54

vii
NOMENCLATURE

ANCO ANCO Engineers, Inc.

ANL Argonne National Laboratory

ASME/ANSI American Society of Mechanical

Engineers/American National

Standards Institute, Standard B16:41

ASME Code The American Society of Mechanical

Engineers Boiler and Pressure Vessel

Code, Section III

Baseline A functional test performed without

Functional dynamic loading to establish a normal

measurement

Bechtel Bechtel Power Corporation

Cloud Robert L. Cloud Associates, Inc.

CPS Containment penetration system,

a design basis and severe accident

study performed under FIN 6322

DIN Deutsche Institute fur Norming

Standards

EPRI

FRG

g

GERB

HDR

HDU

Hydro

Hz

INC

INEL

KfK Kemforschungszentrum Karlsruhe

KWU Kraftwerkunion AG (German

architect-engineer)

LBF Fraunhofer Institut fur Betriebsfestigkeit Darmstadt

LOFT Loss of Fluid Test Facility located

at INEL

MPA Staatliche Materialprfifungsanstalt,

Universitat Stuttgart

Nupipe II A piping analysis computer code

developed by the Quadrex Corporation, Campbell California

OBE Operational basis earthquake

(IEEE 344)

psid Pounds per square inch differential

SHAG Shakergebiude (building shaker)

SHAM Servohydraulische Anregung

Maschinetechnik

SMACS Seismic Methodology Analysis

Chain with Statistics Computer

Code

SSE Safe shutdown earthquake

(IEEE 344)

Starting The frequency in Hz at which the

Frequency shaker was stabilized before the

explosive bolt was fired

T40.XX The numbering system assigned to

each SHAG test

USNRC United States Nuclear Regulatory

Commission

VKL Versuchskreislauf (experimental

piping system)

ZPA Zero period acceleration

(IEEE 344)

AP Differential pressure

Electric Power Research Institute

Federal Republic of Germany

Acceleration equal to the acceleration

of gravity

The GERB Company Berlin

Heissdampfreaktor (superheated steam

reactor)

Heissdampfumformer (steam

convertor)

Hydrostatic Test per ASME Code

Herz (cycles per second)

International NuclearSafeguards

Company

Idaho National Engineering

Laboratory

viii
SHAG TEST SERIES

SEISMIC RESEARCH ON AN AGED

UNITED STATES GATE VALVE AND ON A

PIPING SYSTEM IN THE DECOMMISSIONED

HEISSDAMPFREAKTOR (HDR)

1. INTRODUCTION

The United States Nuclear Regulatory Commission

(USNRC) requires qualification of certain equipment

in U.S. nuclear power plants to ensure that the equipment will operate as designed when subjected to design

basis loadings throughout its design life. Nuclear equipment qualification is typically performed to industry

standards, some of which are justified by only an analytical or extrapolated basis. This is especially true of

qualification standards for line-mounted equipment, for

which dynamic input is always analytically determined.

The SHAG Test Series provides in situ data from a

prototypical piping system subjected to seismic-like

loads.

1.1 Background

pating with KfK in the SHAG test series. These tests

are the first in situ experiments involving an actual

nuclear power plant and a full scale piping system

under simulated seismic loading.

The SHAG tests at HDR provided a unique opportunity to study the behavior of a complete full-scale

nuclear piping system that is supported in a manner

representative of a U.S. installation. During the SHAG

test series, it was possible to subject a valve to normal

fluid loads and seismic-like loads, in combination. It

was also possible to compare the response of the

piping system when supported by the typical U.S. stiff

support system to its response when supported by six

other support systems ranging from very flexible to

stiff.

The INEL equipment qualification involvement with

the HDR Seismic Research Program began in FY-1984

with pretest planning. A test plan was drafted, and

piping support design completed in FY-1985. Construction, instrumentation, and testing took place in

FY-1986.

The Idaho National Engineering Laboratory (INEL),

Environmental and Dynamic Qualification of Mechanical and Electrical Equipment Program, is performing

research to establish a technical basis for assessing the

adequacy of qualification standards and for recommending improvements. The research is performed

under the auspices of the USNRC, Office of Nuclear

Research. Dynamic qualification of line-mounted

mechanical equipment is one area of the research where

industry standards are still in draft form. Results from

the USNRC/INEL participation in the HDR studies can

provide a technical basis for contributions to the effort

to finalize equipment qualification standards.

The current HDR test program is called the HDR

Phase II Sicherheitsprogram (Safety Research Program). The program is being conducted by Kernforschungszentrum Karlsruhe (KfK) in behalf of the

Federal Republic of Germany (FRG) Federal Ministry

for Research and Technology. The SHAG test series

constitutes part of the seismic portion of the HDR

Safety Research Program. Researchers from the INEL

joined with researchers from the Argonne National

Laboratory (ANL), the Electrical Power Research

Institute (EPRI), Kraftwerk Union (KWU), and the

Staatliche Materialpriifungsanstalt (MPA) in partici-

( 1.2 Objectives

The objectives for INEL's participation in the HDR

Seismic Research Program were determined by reviewing the purpose of equipment qualification and the

functional requirements of nuclear piping systems. The

first objective was to measure the effects of various

dynamic and hydraulic loads on gate valve operability, integrity, and response characteristics during a

series of representative seismic events in an in situ

environment. The dynamic loads were varied by modifying the piping support configurations from a base

(typical) U.S. stiff piping support system to form six

other systems ranging from a very flexible support

system to a very stiff energy absorbing support system

(described in Section 2), and by varying the magnitude

and frequency of the excitation.

The second objective was to obtain data so that valve

response to multiaxial, in situ seismic loads could be

I
compared with valve response to single effects loadings

typical of valve qualification testing.

The third objective was to obtain piping system

response data (strain, acceleration, force, and displacement) for the base system and the six other support

systems during a series of reasonably representative

simulated seismic events. The information is to be

used to evaluate support system methodology, snubber performance, and snubber replacement device

performance, and to verify the SMACS (Seismic

Methodology Analysis Chain with Statistics) computer

code.

Because of the large amount of information generated by the SHAG Test Series, this report is published

in two volumes. Volume 1 presents a summary of the

tests and the results, and Volume 2 contains appendices that present details and specifics.

1.3 Qualification Standards and

Regulatory Guides

* Institute of Electrical and Electronic Engineers,

Design Qualification of Safety Systems Equipment Used in Nuclear Power Generating

Stations, IEEE Standard 627, 1980

* United States Nuclear Regulatory Commission, Development of Floor Design Spectra for

Seismic Design of Floor-Supported Equipment

or Components, Regulatory Guide 1.122

* United States Nuclear Regulatory Commission, Damping Values for Seismic Design of

Nuclear Power Plants, Regulatory Guide 1.61

* United States Nuclear Regulatory Commission, Functional Specificationfor Active Valve

Assemblies in Systems Important to Safety in

Nuclear Power Plants, Regulatory Guide 1.148

* United States Nuclear Regulatory Commission, Seismic Qualification of Electric Equipment for Nuclear Power Plants, Regulatory

Guide 1.100

* United States Nuclear Regulatory Commission, Qualification Tests of Electric Valve

Operators Installed Inside the Containment of

Nuclear Power Plants, Regulatory Guide 1.73

The following equipment qualification standards and

regulatory guides are potentially affected by HDR

research results.

* American Society of Mechanical Engineers,

Functional Qualification Requirements for

Power Operated Active Valve Assemblies for

Nuclear Power Plants, ANSI/ASME B16.41,

currently being revised as ANSI QV-4

* American Society of Mechanical Engineers,

Self-Operated and Power-Operated SafetyRelated Valves Safety Specification Standard,

ANSI/ASME N278.1-1975

* Institute of Electrical and Electronic Engineers,

Recommended Practices for Seismic Qualification of Class JE Equipmentfor Nuclear Power

Generating Stations, IEEE Standard 344,

1975

* Institute of Electrical and Electronic Engineers,

Qualification of Safety-Related Valve Actuators, IEEE Standard 382, 1980

)L United States Nuclear Regulatory Commission, USNRC Standard Review Plan, Section

3.9.3., ASME Code Class I, 2, and 3 Components, Component Supports, and Core Support

Structures, NUREG-0800, 1981

* United States Nuclear Regulatory Commission, Qualification and Acceptance Tests for

Snubbers Used in Systems Important to Safety,

Draft Regulatory Guide SC 708-4, Rev. 1,

1981

* American Society of Mechanical Engineers,

Examination and Performance Testing of

Nuclear Power Plant Dynamic Restraints

(Snubbers), ANSI ASME OM4, 1982

* American Society of Mechanical Engineers,

Boiler and Pressure Vessel Code, Section Xl,

Subsection IWF, Requirements for Class 1, 2,

3 and MC Component Supports of Light- Water

Cooled Power Plants, 1986 edition.

2
2. TEST DESCRIPTION

2.1 The Heissdampfreaktor (HDR)

The HDR is a decommissioned experimental reactor

facility located near Frankfurt in the Federal Republic

of Germany (FRG). The facility (Figure 1) was modified in two areas for the SHAG portion of the HDR

Safety Research Program. One, we mounted a very

large twin-arm rotary mass coastdown mechanical

shaker or seismic simulator (Figure 2) to the operating

floor at the 30-m level. Two, we modified an existing

piping system called the Versuchskreislauf (VKL) by

installing an aged 8-in. motor-operated gate valve of

U.S. nuclear origin, a dynamic pipe support system

typical of U.S. nuclear design, and 103 instruments

on the piping system and on the Heissdampfumformer

(HDU), a large vessel, similar to a steam generator,

to which part of the piping system is attached (Figure 3). HDR pipe sizes, internal pressure, temperature,

flow media, valve operation, and dynamic supports all

represent reasonable commercial nuclear conditions

and provide an outstanding test bed for in situ seismic

research.

2.2 Seismic Simulator

The SHAG Test Series conducted at the HDR facility

consisted of mechanical excitation of the HDR building

and the resulting excitation of the systems and components inside the structure. Excitation of the building

was accomplished by a large, twin-arm, eccentric mass

coastdown shaker designed by ANCO Engineers, Inc.

Various amounts of weight can be bolted to the revolving arms to produce different amounts of input energy

to the building. The shaker was spun up with its

weighted arms in balance (at 180 degrees) to the

desired starting frequency, and then the motor was

disengaged for coastdown. Then an explosive bolt was

set off to allow the arms to swing together, creating

a revolving eccentric mass that imparted the mechanical

loading to the highest structural floor [30 m (100 ft)]

in the building.

Tests were performed with starting frequencies from

1.6 to 8 Hz. Shaker input to the building for the 8 Hz

tests exceeded 90 s in duration. The complex dynamic

response of the building caused the components and

systems in the building to respond with both vertical

and horizontal motion.

For each experiment, the shaker was weighted with

a specified amount of weight bolted to the shaker arms.

In general, the amount of weight varied inversely with

the starting frequency scheduled for the experiment.

Twenty-five experiments were performed, as shown

in Table 1 and as summarized in the following list:

Starting

Frequency

1.6 Hz

2.1 Hz

4.5 Hz

Number

of Tests

3

1

6

Starting

Frequency

5.6 Hz

6 Hz

8 Hz

Number

of Tests

1

6

8

Total 25

2.3 VKL Piping Support Systems

The VKL is located between the 18- and 24-m elevations in the HDR facility, as shown in Figure 1. The

VKL consists basically of two parallel flow loops connected to the HDU and to a manifold or header

(DF 16), as shown in Figure 3. The VKL is constructed of stainless steel in four pipe sizes. Fluid in

the system is electrically heated, and the system is

capable of operating at pressurized water reactor

(PWR) secondary or boiling water reactor (BWR)

primary pressure and temperature conditions. One of

the parallel flow loops was orificed to provide maximum differential pressure across the installed valve.

USNRC provided the aged, 8-in., motor-operated gate

valve from the decommissioned Shippingport Atomic

Power Station, where it had served approximately

25 years as a feedwater safety injection isolation valve.

INEL thoroughly refurbished the valve and added a

total travel valve position device to the valve stem,

which supplemented the limit switches to aid in valve

signature analyses. Deutsche Institute fur Norming

(DIN Standards) apply for installations in German

plants. The ASME code and ANSI B16.41 were acceptable substitutes. Testing included hydro, proof,

leakage, and baseline functional tests and seismic fundamental frequency determination.

INEL analyzed the VKL, and, using the NUPIPEII computer code, the response spectra analysis techniques, and equations of NC-3600, summer 1979

addenda of the ASME code, designed a dynamic piping

support system for the VKL that was representative

of a typical U.S. stiff support system. It was designed

using typical U.S. struts and snubbers, sized for

predicted loads at Level B allowables. Upset allowables were used owing to the uncertainty of KfK's

input spectra. The manufactured supports, snubbers,

struts, pipe clamps, pins, etc. were purchased from

U.S. nuclear suppliers. The framework and anchors

were purchased locally in Germany. HDR craftsmen

3
K 50 m

30 m

VKL

Room

Reactor

PressureVessel

C m

- -10 m

MGH1088-1

Figure 1. A simplified cross section of the HDR facility, showing the locations of the shaker, the VKL, and the reactor

pressure vessel.

4
Driven arm

aMrovable j I 

arm

1~~~~~~~~~~~~

7-7341

Figure 2. The large twin-arm rotary mass coastdown mechanical shaker used to produce the simulated seismic excitation.

5
H-24 H-17

Constant force- 7 Constant force

spring hanger / / spring hanger

Figure 3. A schematic drawing of the VKIL showing the 8-in. motor-operated gate valve and the U.S. stiff piping support system.

6
Table 1. Test matrix

Temperature

Test (C)

T 40.34

T 40.35

T 40.36

T 40.37

T 40.40

T 40.20

T 40.60

T 40.50

T 40.70

T 40.10

T 40.30

T 40.31

T 40.41

T 40.21

T 40.11

T 40.51

T 40.52

T 40.32

T 40.42

T 40.12

T 40.22

T 40.12A

T 40.14

T 40.16

T 40.13

20

20

20

20

20

20

20

20

20

20

20

20

20

20

20

20

210

210

210

210

50

210

40

30

30

Support

Configuration

3

3

3

3

4

2

6

5

7

1

3

3

4

2

1

5

3

4

l

2

1

1

1

1

Eccentricity

(kg/m)

4700

4700

8200

27800

4700

4700

4700

4700

4700

4700

4700

6450

6450

6450

6450

6450

8200

8200

8200

8200

8200

8200

33000

54000

67000

Frequency

(Hz)

6.0

8.0

5.6

2.1

8.0

8.0

8.0

8.0

8.0

8.0

8.0

6.0

6.0

6.0

6.0

6.0

4.5

4.5

4.5

4.5

4.5

4.5

1.6

1.6

1.6

VKL Flow

(tons/h)

90

90

90

90

90

90

90

90

90

90

90

90

90

90

90

90

90

90

90

90

90

90

90

0

0

Valve

Operation

Cycle

Cycle

Cycle

Cycle

Cycle

Cycle

Cycle

Cycle

Cycle

Cycle

Cycle

Cycle

Cycle

Cycle

Cycle

Cycle

Cycle

Cycle

Cycle

Cycle

Cycle

Cycle

Cycle

Open

Open

a. Support configuration:

1 = KfK very flexible

2 = KWU moderately flexible

3 = U.S. stiff

4 = EPRI/Bechtel energy-absorbing

5 = EPRI/Cloud impacting

6 = GERB energy-absorbing

7 = ANCO energy-absorbing

installed the supports under supervision of INEL

engineers. This support system, by component removal

or replacement, also formed the basis for the six other

participants' piping support configurations.

Six struts and six snubbers (5 mechanical and 1 hydraulic) were added to the existing dead weight support system to constitute the U.S. stiff piping support

system. The dead weight system included six Grinnell

spring and constant force supports and one threaded

rod hanger. An additional spring hanger (H-13) was

installed to account for the added weight of the U.S.

gate valve that was installed. The dead weight supports

were typical of those in U.S. nuclear piping systems.

Figure 3 identifies the locations of the supports. The

dead weight support configuration was not changed

during the program.

Six other dynamic piping support systems were

tested in addition to the U.S. stiff system. These additional piping support systems included a very flexible

system (designed by KfK), a moderately flexible

7
system (designed by KWU), and four energy-absorbing

support systems. The four energy-absorbing systems

included an impact system [sponsored by the Electrical

Power Research Institute (EPRI) and designed by

Robert L. Cloud Associates, Inc.], a ductile flexure

system (sponsored by EPRI and designed by Bechtel

Power Corporation), and two viscous mass energyabsorbing designs (one by GERB Berlin, and the other

by ANCO Engineers, Inc.). The energy absorbing

systems varied in design stiffness from the flexible

EPRI-Bechtel system to the ANCO system, which at

ambient conditions was stiffer than the U.S. stiff

system. We compared the seven systems by conducting several tests, at the same starting frequency and

conditions but with different support systems, and

measuring the operability of the valve and the responses

of the piping system and of the valve in terms of acceleration, strain, force, and displacement. All seven

systems were tested at the 8-Hz starting frequency.

Five of the seven systems were tested at the 6-Hz and

4.5-Hz starting frequencies.

Descriptions of the seven support systems and the

locations of specific items of equipment used in each

support system are summarized in Table 2 and are

given in the following list. Figure 3 shows the installed

U.S. stiff system and identifies the locations (H-1, H-2,

etc.) where the components were installed. In general,

the U.S. stiff system, by component removal or replacement, served as the basis for the other systems.

However, the GERB system included an energyabsorbing device placed at a location not shown in

Figure 3. Figure 4 shows the installed GERB support

configuration and identifies that additional location

(near H-11).

Configuration 1 ('ICK, veryflexible). All snubbers

and struts were removed except the two struts at

H-4 and H-5.

Configuration 2 (KWU, moderatelyflexible). All

snubbers and one strut, H-3, were removed.

Configuration 3 (U. S. stiff). The six struts and six

snubbers (one hydraulic and five mechanical) were

left in place. The struts, typical of those used in

nuclear piping systems, were located at H-3, -4,

-5, -9, -10, and -11. Initially, there were four

International NuclearSafeguards Company (INC)

mechanical snubbers, located at H-6, -7, -8, and

-12; one Pacific Scientific mechanical snubber,

located at H-i; and a Bergen-Patterson hydraulic

snubber, located at H-2. After their failure during the preliminary tests, the four INC mechanical

snubbers were replaced with Pacific Scientific

mechanical snubbers for the comparison tests.

Configuration 4 (EPRI/Bechrel). The six snubbers

were replaced with four energy absorbers at H-i,

-6, -7, and -8. Snubber positions H-2 and H-12

were omitted. The six struts remained in place.

The energy absorbers are pin-to-pin replacements

for snubbers. The devices use ductile flexures to

absorb dynamic energy.

Configuration 5 (EPRI/Cloud). The six snubbers

were replaced with six seismic-stop energy absorbers. The six struts were left in place. We expect the seismic stop to develop into a pin-to-pin

replacement for snubbers. The devices absorb

energy through impact in a manner typical of common box beam supports.

Table 2. Type of supports used in the HDR/VKL tests

Support System

System

Numbera

Viscous

Mass

Struts Snubbers Supports

U.S. stiff

KfK very flexible

KWU flexible

EPRI/Cloud impacting

EPRI/Bechtel energy-absorbing

GERB energy-absorbing

ANCO energy-absorbing

3

1

2

5

4

6

7

6

2

5

6

6

5

6

6b

0

0

0

0

0

0

0

0

0

0

0

2

6

Impact

Supports

0

0

0

6

0

0

0

Flexure

Supports

0

0

0

0

4

0

0

a. We have retained the numbers chosen by KfK in order to facilitate cross-referencing among reports.

b. Five mechanical snubbers and one hydraulic snubber.

8
H-24 Ccnt force

sprin h--er

H-17

Constaot force

sprirs hanger DF16

Y

* x

H-1I

Strut \

Flow

-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

H-16

Corntant force

spring honger

20C>r,,'

(8'1

HOU

H-18

Constant force

spring hFoger

Vdve detol

H-10

Strut 200mn-y

(e)

H-15

Threoded rod

'-9

Strut -\

H-5

Strut

H-14

Spring

horie

H-7-8

Location

1 O1 rrr

(4")

BMGOO171

Figure 4. GERB VKL schematic showing the piping support system.

9
Configuration 6 (GERB). Five of the struts were

retained; the one at H-3 was removed. The six

snubbers were replaced with two biaxial viscous

mass energy absorbers. The units were placed at

the H-7 and -8 location and at a special location

near the H-II location (see Figure 4). This energy

absorber uses a highly viscous bituminous liquid

inside a small vessel with a damping rod. The system was tested only at the 8-Hz starting frequency.

Configuration 7 (ANCO). The six snubbers were

replaced with six viscous mass energy absorbers,

based on GERB viscous dampers, which were configured to be pin-to-pin replacements for snubbers.

The six struts were retained. The system was tested

only at the 8-Hz starting frequency.

2.4 Gate Valve

USNRC provided the 8-in. motor-operated gate

valve from the Shippingport Atomic Power Station.

Prior to its use in the HDR Seismic Research Program,

INEL disassembled and inspected the valve and subjected it to nondestructive examination as part of the

USNRC Nuclear Plant Aging 'Research (NPAR)

Program. After the nondestructive examination was

completed, repairs were made to one of the valve's

sealing surfaces, a new safe end was welded on, and

two new flanges were welded to the safe ends. The

electrical components of the actuator were checked and

cleaned, and the valve was reassembled and remated

with the actuator. A more complete description of the

valve is given in Appendix A, in Volume 2 of this

report. Appendix A also describes the results of INEL's

disassembly, inspection, and refurbishment of the gate

valve in terms of the NPAR Program.

2.5 Instrumentation

INEL used 103 instruments, in addition to 57 installed by KfK, to monitor the response of piping

system, the performance of the gate valve, snubbers,

and snubber replacement devices, and the dynamic input of the support anchors to the VKL. Instrumenting

the VKL and the HDU vessel was based on piping

system analysis, system response characterization, and

valve operability, piping system, and snubber requirements. The instrumentation (shown in Figure 5)

measured acceleration, displacement, strain, force,

temperature, pressure, differential pressure, valve position, and valve operator motor amperage and voltage.

Appendix B (also in Volume 2) gives more information about the instrumentation of the piping system and wl

equipment and a list of all the instruments installed.

10

3. TEST RESULTS

Sections 3.1, 3.2, and 3.3 provide a general characterization of the HDR loadings and describe the

behavior of the load path from the shaker to the VKL

piping system. Sections 3.4 and 3.5 give a report on

the performance of the piping support systems and their

components, and Section 3.6 describes the performance

and the dynamic response of the valve.

E

C

0

a)

sa)

0)

0)

5

4

3

2

1

0

-1

-2

-3

_--- . H., ............................ . . ....

3.1 Building Response 0 6 12 18 24 30 36 42 48 54 60

Time (s)

Before the tests were conducted, calculations were

performed to predict the maximum VKL excitation

loadings for each starting frequency. These predictions

were based on building safety studies and included

calculations of input from the shaker to the building

and input from the building to the VKL. The actual

shaker output loads and building acceleration and strain

loads as measured during the first four tests were used

to verify predicted loads, and shaker output loads for

subsequent tests were adjusted accordingly. These adjustments consisted of reductions in the loadings at mid

to low frequencies, which correspond to the building's

natural frequencies, to accommodate building strain

limitations. The decreased inputs at the mid and low

frequencies did not affect the piping and valve research

because the maximum responses for the piping system

were achieved at the 6- and 8-Hz shaker starting frequencies, which envelop most of the piping system

natural frequencies.

Note that for the following discussion of HDR

building and HDU vessel responses, all results are

presented for 8-Hz starting frequency tests. Also, since

building and HDU responses are independent of VKL

piping support configuration, no designation is given

concerning piping support configuration.

Building responses in the VKL area of the building

were fairly uniform for each of the three axes; no part

of the structure for a given direction participated more

than another. Figures 6, 7, and 8 show acceleration

responses of the building at a location near the bottom

of the HDU; Figures 9, 10, and 11 show responses

at a location near the top of the HDU; Figures 12

and 13 show building responses at support locations

H-I and H4. Figure 14 provides locations, axes, and

units of measurement for the responses shown in

Figures 6 through 13. The figures show an average

peak response of 0.25 to 0.3 g in the X and Z directions and 0.08 to 0.1 g in the vertical direction Y.

Figure 15 shows a typical building acceleration in

response spectrum format. The response is influenced

primarily by the shaker frequency at 7 Hz and a

Figure 6. Building response, X axis, near bottom of HDU

(instrument number 700).

N 0.8

-E 0.6

c 0.4

CDo_ 0.2

a, -0.2

') - 0.4

< -0.6

- 0.8

M

WF=I I I I I

M_,Ll I l. I I

E f~~~~~t26!'l

II ' I I I I I I I I I

0 6 12 18 24 30.

Time (RI

36 42 48 54 60

-I 9.0653 .. 

Figure 7. Building response, Y axis, near bottom of HDU

(instrument number 701).

a6, 5

Cn 4

' 3

o 2

a - 1

< -2

-3

T ~~~I I I IIXL

.~~ ~~~~~ IL _ ~ ____ ~ ~ ~ ~ ~ ~ _ . ._..

0 6 12 18 24 30 36 42 48 54 60

Time (s)

Figure 8. Building response, Z axis, near bottom of HDU

(instrument number 702).

building frequency of 1.2 Hz, with a ZPA of 0.3 g.

The spectrum was developed from an acceleration

time history recorded at a building location near H-7,

starting shortly after test initiation, and represents

13
jT- 5

4 4

~93

C 2

00

W 1

O

C-2

< -2

I I I I I I

I . . I . I I . .

I I I I I

_~~~~~~~~~~~~~~I -. ;wlu. i...*.-....-

0.4

-a 0.3

-C 0.2 L

0 0

- 0.1

0

c., - 0.2

- 0.3 1

- 0.4 11

104.99 116.99 134.99 146.99 158.99

Time (s)

0 6 12 18 24 30 36 42 48 54 60

Time (s) 9-0650

Figure 9. Building response, X axis, near top of HDU (instrument number 703).

- 2.00

.2 1.50

E 1.00

C 0.50 0

0

a)-0.50

0-1.00

.X -1.50

-2.00

- I p~ m -I

LLL0~~.1 .__. y.4,.

0 6 12 18 24 30 36 42 48 54 60

Time(sx 10)

Figure 12. Building response, X axis, at piping support H-I

(instrument number 56).

04

0.1

0) _0,1

0.1

104.99 116.99 128.99 140.99 152.99164.99

Time (s) 9-0645

Figure 13. Building response, Z axis, at piping support H-4

(instrument number 59).

Figure 10. Building response, Y axis, near bottom of HDU

(instrument number 704).

2.00

.5 1.50

c 1.00

C 0.50 _q! .0

'Z r_ L~

T -0.50

o 1 2 . 0 o 0 rr0 r 

< -1.50 " - 2.00 FI

Instrument nu

703, 704, 705

0 6 12 18 24 30 36 42 48 54 60

Time (s x 10) 9-0642

Figure 11. Building response, Z axis, near top of HDU (instrument number 705).

:mbers Instrument

/number56

d> I

w/8'

Instrument

NH-4 number 59

Instrument numbers

700,701,702

I-lIT-I ~~9 .0 587

Figure 14. Instrument locations for Figures 6 through 13.

14
2~

0

-~1.6.

Co

1.4-

Z 1.2-

0 F '8

0.6 0 .4~

0.2

0-

0 2 46 8 10 12 14 16 1B8

Frequency (Hz) 4

Figure 15. Typical acceleration response spectrum of the

structure in the HDR building.

approximately a 7-s window. Figure 16 shows a typical

shaker coastdown from 8 Hz; the shaker frequency is

shown in the vertical axis and time in the horizontal

axis, with a duration of 100 s. Comparison of this

coastdown curve to the building acceleration histories

(Figures 6 through 13) indicates that the highest

responses were obtained in the early portion of the test.

Figure 17 illustrates the settling of the reactor building

in the ground before and after the SHAG experimental series. Figure 18 shows various cracks in the earth

around the building after one of the lower starting frequency tests.

The actual forces applied to the building, in the frequencies of interest for piping and valve research

(6 and 8 Hz), met the SHAG design requirements and

provided significant excitation to the HDU and piping

system. The building responses were uniform in each

of the horizontal global axes. Vertical input to the

20

'37

piping system was obtained, owing to the complex

response of the building. ZPAs up to 0.3 g were input

to the HDU and piping system supports. The resulting

piping responses were more than adequate for the intended research.

3.2 HDU Vessel Response

The response of the VKL was influenced primarily

by motion of the HDU vessel, not by the acceleration

input at the support locations. Figure 19 compares

anchor motion (in response spectrum format) in the two

horizontal axes at the HDU mid-height support to the

building response at support location H4. The figure

shows significantly more amplification in the HDU

support than in the building. Figures 20, 21, and 22

present the acceleration responses recorded at the top

of the HDU. Figure 23 provides locations of measurement, definition of axes, and units of measurement.

A comparison of Figures 9, 10, and 11 with Figures

20, 21, and 22 shows that through the piping attached

to the top of the vessel, the HDU had a greater influence on piping system response than did the supports

connected to the building structure. The response of

the vessel is 5 times greater, on an average in all axes,

than the building response.

l _49.4 April 4, 1986

l -56.8 August 8. 1986

2~~ \ ~, + 7.4

__I X

-119.0 |-815

-130.6 -84.8

A - 11.6\ A - 3.3

[ 91,3 |

-96.6

-_ 5.3

7-7340

Measurements in mm

Figure 17. Comparison of building foundation elevation

before and after the SHAG experiments.

*1$4'at* s PO U.n WeM

ISHAG ,2 An

n u."v40

7.20

w 6.00-

0 4.80 C

a)

-3.60

-L 2.40'

1.20

* I J .. . . . .. . .. .. - - -- -- -

.no0

-1.00 .001.00'2.00 3.00 4.00 5.00 6.00 7.00 8.009.0010.00

Time (s x 10) 9-0654

Figure 16. Shaker coastdown history from an 8-Hz starting

frequency.

15
Figure 18. Ground damage 2 to 4 m from building foundation.

16
14

12-

10-

0 8- 0

*) 6-

, 4'

2-

-. 25

~20

~15

010 iA .A

.~ 0

a) 5-

<-10

:-15 L l

-5 0 5 10 15 20 25 30 35 40 45 50

Time (s) 9.0651

Figure 22. Acceleration history at the top of the HDU in

the Z direction (instrument number 8-3).

0 20 40

Frequency (Hz)

Figure 19. Response spectra derived from measurements

taken from HDU supports (instrument number

15) and from a nearby wall (instrument number

59). Locations are shown on Figure 23.

Instrument numbers

u) 6 1IL,. I I Is I

E 4 1[Gl1. - 2

CD)-42 1 

7 -6 4

-5 0 5 10 15 20 25 30 35 40 45 50

Instrument number

i/ D . '>t t1;'< A,.' tnstrument number

Threaded rod / \ | 8 15

StruI - Spring >'*

hanger W ha\gdr g5S 1EInstrument

- ~~~number 59

"4" Snubber

9-0686

Figure 23. Instrument locations, axes, and units of measure

for Figures 19 through 22.

Time (s)

Figure 20. Acceleration history at the top of the HDU in

the X direction (instrument number 8-1).

-4 E 3

o~ 2 0

.2 1 Eto -1 Ff

<-2

-3

-5 0 5 10 15 20 25 30 35 40 45 50

Time (s)

Figure 21. Acceleration history at the top of the HDU in

the Y direction (instrument number 8-2).

The magnitude of the HDU vessel response was not

anticipated from pretest analyses. The vessel input to

the piping system provided loadings expected of SSE

inputs. Note also that the response of the HDU vessel

was not influenced by the support configuration installed on the piping; this response was the same with

the U.S. stiff support system as it was with the flexible KfK support system. Because the HDU is the

primary influence on piping system response, and is

not influenced by the piping support configuration, we

have a uniform basis, for a given starting frequency,

on which to compare the influence that the various

piping support configurations had on piping and valve

responses.

17
3.3 VKL Piping System Response

Of the 25 seismic experiments conducted on the

VKL, 17 are of interest for valve and piping response

research. The 17 experiments included 7 tests performed at 8 Hz, 5 tests at 4.5 Hz, and 5 tests at 6 Hz.

Of the remaining 8 tests, some were preliminary tests

and the others had starting frequencies that were too

low to excite the piping system to meaningful response

levels.

It was assumed in the initial analysis that the most

flexible system (KfK) and the most rigid system (U.S.

stiff) enveloped the piping system responses. This

proved true, except that one of the snubber replacement systems may have been stiffer than the U.S. stiff

system. The snubber replacement systems are discussed in Sections 3.4.3 and 3.5.

The highest overall piping system responses were

observed in the tests starting at 6 Hz with both the stiff

system and the flexible system. The peak responses

in the 8-Hz tests were slightly lower than those in the

6-Hz tests, and all levels of responses in the 4.5-Hz

starting frequency tests were significantly lower. The

responses were largest in the 6-Hz tests because of the

coincidence of a major piping system resonance near

6 Hz. These resonances are apparent in the 8-Hz tests,

but the responses are not as large as those as achieved

in the 6-Hz tests. Figures 24 through 27 are typical

histories of shaker frequency and shaker force. As

shown in Figures 24 and 25, during an 8-Hz test the

shaker slows to 6 Hz about 5 s after test initiation, and

the shaker input force was about 7000 kN at 5 s.

Figures 26 and 27 are the frequency and force histories

from a 6-Hz starting frequency test; in this test,

9000-kN input force was observed at the same 6-Hz

frequency. We assume that the greater available input

energy at resonance is the main reason for greater peak

responses during the 6-Hz tests.

Figures 28 through 31 are acceleration histories

recorded during the 8- and 6-Hz tests in the X direction just downstream from the H-7-8 snubber location,

with either the flexible system or the stiff system installed. Figure 32 shows the location. Figure 28 is the

acceleration history from the 8-Hz test with the KfK

0

C

0)

U8.40

7.20

6.00

4.80

3.60

2.40

1.20

.00

... i. :. . .. :.. ....... : .

--- -- . ,A.. ....... ........ ..-- ,;...... -- - -- -

-.- - - - - ------- .-. : \: I : : :------- ------

0~

a,

LJ.

8.40

7.20

6.00

4.80

3.60

2.40

1.20

.00

.................. --------------

j L ... .... .... .. .

---- ---- . ...

---------

.00 2.00 4.00 6.00 8.00 10.00

Time(sx 10)

.00 2.00 4.00 6.00 8.00 10.00

Time(sx 10)

Figure 26. Shaker frequency coastdown history for a 6-Hz

test.

Figure 24. Shaker frequency coastdown history for an

8-Hz test.

14.00

0 12.00 E

0 10.00

x 8.00

M6 6.00

a)

2 4.00

IL 2.00

.00

. . . . . --- --- --.---

.~ ~ ~ ~ ~ ~~~~~ ----- ---

-- .. - ... - .. -.

x6

z

0

IL

14.00

12.00

10.00

8.00

6.00

4.00

2.00

.00

.

............

.00 .0 2.00 . . 4.00 . . 6.00 . . 8.00 . 10.00 1 0 .0 0

Time (s x 10) 9-0652

Figure 25. Shaker force history for an 8-Hz test.

.00 2.00 4.00 6.00 8.00 10.00

Time(sxl10) 90646

Figure 27. Shaker force history for a 6-Hz test.

18
C

0

a,

a)

C.

V

20.00

15.00

* 10.00

5.00

.00

-5.00

-10.00

- ir. nn

------------------ ----------------

------ ------------ ----

"AiLl-

------------- --------------

a,

E

C,

C.,

Q

24.00

16.00

8.00

.00

- 8.00

-16.00!

- 24.00,

_) 3 nn

-------------

---- ........ ------------------------

------------------- ........... .

----------------------------- --

--------------------- _------

.00 2.00 4.00 6.00 8.00 10.00

Time (s x 10)

Figure 28. VKL acceleration history recorded at instrument

location 10 in the X direction during an 8-Hz

(starting frequency) test with the KfK flexible

support system installed.

so -68.00

(D 8.00 ..I.. ~.. ..... .... .. -- - - - - - - -

24.00 -

.00 2.00 4.00 600 8 0 10.00

Time (s x 10) 9-0649

Figure 29. VKL acceleration history (at 10 X) recorded during a 6-Hz test with the KfX flexible support

o16.00~ system 2installed.

24.00

32.00

.00 2.00 4.00 6.00 8.00 10.00

Time (s x 10)

Figure 30. VKL acceleration history (at l0-X) recorded during an 8-Hz test with the U.S. stiff support

system installed.

.00 2.00 4.00 6.00 8.00 10.00

Time (s x 10) 9-0644

Figure 3 1. VKL acceleration history (at lOX) recorded during a 6-Hz test with the U.S. stiff support system

installed.

y

x

number 10

Figure 32. Instrument location for Figures 28 through 3 1.

flexible system, and shows resonance buildups occurring at shaker frequencies of near 6 and 4.5 Hz. Figure 29 shows the corresponding measurement from the

6-Hz starting frequency test. The near-6-Hz resonance

is not excited; however, a 4.8-Hz resonance is. Figures 30 and 31 show the measurements from the 8- and

6-Hz starting frequencies with the U.S. stiff configuration. In the 8-Hz test, a major resonance is indicated

at a shaker input frequency of 5.7 Hz. This resonance

19
point is below 6 Hz. In the 6-Hz stiff system test, this

resonance point is excited to almost double the acceleration measured during the 8-Hz test. This comparison

is fairly typical of measurements taken throughout the

piping system. The flexible system has resonance

points both above and well below the starting frequencies of 6 and 8 Hz, whereas the stiff system has a major

resonance just below 6 Hz and is excited by this starting frequency.

This higher frequency resonance is expected from

stiff support system design. Stiff piping systems were

thought to be preferable to flexible piping systems

because their natural frequencies are removed further

from the significant frequencies associated with the

building frequencies (normally low) than flexible

systems, thus reducing the effect of resonance interaction between the building and the stiff systems.

Though greater acceleration response was measured

with the U.S. stiff system than with the KfK flexible

system, higher strains and forces were measured with

the KfK flexible system. Frequency analyses of acceleration histories presented in Section 3.6.2 of this

report indicate that a major vertical low-frequency

response is present in the KfK system that is not present

in the U.S. stiff system. It appears that the vertical

responses are a primary influence on the strains and

forces at the spherical tee with the KfK flexible system

and may be attenuated by the vertical snubber (H-6)

in the U.S. stiff system.

Tables 3 and 4 are peak response matrices for the

seven 8-Hz and five 6-Hz starting frequency tests for

all measured VKL responses. The matrices are designated according to global axes and are sequenced corresponding with fluid flow through the pipe starting

at and returning to the HDU. These tables report

average peak response. The matrices provide a comparison of all time responses for all seven support

systems and for the two starting frequencies that had

the greatest influence on piping response.

3.4 Performance of Snubbers

and Snubber Replacement

Devices

Two types of snubbers were used in the U.S. stiff

piping support system-five mechanical snubbers and

one hydraulic snubber. The hydraulic snubber was

produced by Bergen-Patterson. Initially, four of the

mechanical snubbers were of INC design, and the fifth

was manufactured by Pacific Scientific.

The INC snubbers were in place during only the

preliminary shakedown tests. During those tests, we

discovered that the INC snubbers were functioning

erratically. We replaced the INC snubbers with Pacific

Scientific snubbers for the remaining tests. Appendix C

(Volume 2) describes the different kinds of snubbers,

documents the poor performance of the INC snubbers

during the preliminary tests, and presents the results

of the investigation that followed. After checking with

the NRC staff and the snubber manufacturers, we concluded that the once popular INC snubbers have been

removed from operating utilities and are not a safety

problem.

In general, four measured responses are of interest

for each snubber location in the HDR test series. These

are the force in the snubber, the pipe-to-wall relative

displacement, the pipe absolute acceleration, and the

wall absolute acceleration. Refer to Figure 3 for locations and orientations of snubbers. Figure 5 shows the

instrumentation. Snubber locations are explained in

Section 2.3.

The forces were sensed by pins (Figure 33) specially

made for these tests by Tricoastal Industries of Seattle,

Washington. The individual pins were sized to fit one

of the snubber end connections. Strain gages within

the pin were calibrated to measure the load transmitted

through the snubber.

Displacements were measured with a Celesco

PTIOI-20A position transducer (Figure 33). Piping

accelerations were measured at locations adjacent to

the support connection using PCB and Endevco

piezoelectric transducers (Figure 33).

INEL and MPA recorded all measurements on

analog and digital magnetic tape, with the exception

of acceleration location 9, which was digitally recorded

by KfK.

3.4.1. Performance of Pacific Scientific Mechanical Snubbers. Measurements of force through the

snubber pins and acceleration of the piping indicate that

the Pacific Scientific snubbers performed within the

manufacturer's specified tolerances, except for the

snubber at H-1 for a 3- or 4-s period during test

T40.30, when the measured force dropped to nearly

100 lb (see Figure 34) and the acceleration increased.

The anomaly was self-correcting, and the phenomenon

did not occur again in this or other tests, nor did it

occur at any of the other Pacific Scientific snubber

locations.

Figure 35 provides an example of the four responses

measured at one of the snubber locations. The force

history plot for this Pacific Scientific snubber shows

that it was resisting motion, but the displacement

history shows that the snubber allowed greater dead

band displacements than specified by the manufacturer,

0.1 in. peak to peak. This response was typical of all

snubber locations, including the hydraulic snubber at

the H-2 location. The displacements were measured

20
Table 3. Peak response matrix for all support systems at 8-Hz starting frequency

Instrument

Number

X AXIS

15-1

8-1

7-1

25

76

17

56

27

18-1

58

16-1

t') 9-1

23

60

3-2

3-3

37-2

37-3

40-1

41-1

42-1

10-1

32

21

65

11-I

2-2

2-3

35-1

22-1

Unit of

Measure Location U.S. Stiff ANCO Bechtel Cloud KfK KWU GERB Remarks

A HDU support

Top of HDU

Bottom of HDU

H-I

H-I

H-I pipe

H-I wall

H-3

H-3 pipe

H-3 wall

Normal tee

SP tee

H-5

H-5 wall

Pipe bt H-5 and valve

Pipe bt H-5 and valve

Valve nozzle

Valve nozzle

Valve body

Valve CG

Valve actuator

El dwn st of reducer

H-10

H-10 pipe

H-10 wall

Pipe upstr of H-10

Nozzle DF 16

Nozzle DF 16

Nozzle DF 16

Body DF 16

±3 g peak

±1.8 ave

±6.5 m.s 2

M

±1200 lb

±.82 in.

±2.75 g

±.2 g

±2400 lb

± 1.63 g

±.3 g

±1.5 g

± 10 mIS2

±8000 lb

±.2 g

±180 u

±160 u

±90 u

±65 u

±1.43 g

±1.25 g

±11 m/s2

±750 lb

±1.10 g

±.2 g

±19 m/s2

±33.5 u

±39.5 u

±12 m/s2

±1.15 g

±3 g peak

±1.8 ave

±6.5 m/s 2

M

±1250 lb

±.60 in.

±1.6 g

±.2 g

±1750 lb

±1.13 g

±.3 g

±.85 g

±6.5 mWs2

±6300 lb

±.2 g

±175 u

±162 u

±80 u

±60 u

±1.25 g

±1.05 g

±7.5 m/s 2

±775 lb

±.98 g

±.2 g

±31.5 m/s 2

±35 u

±47.5

i±1.5 m/s 2

±1.30 g

2 g peak

±2.15 ave

±10.5 m/s 2

M

±1300 lb

±.78 in.

±2.0 g

±.2 g

±3125 lb

±2.2 g

±.3 g

±1.5 g

±7 mrs2

±7500 lb

±.2 g

±37.5 u

±32.5 u

±117.5 u

±87.5 u

±1.93 g

±1.90 g

±2.40 g

±9 m/s 2

±825 lb

±1.10g

M

±35 m/s2

±52 u

±87.5 u

± 12 m/s2

±1.30 g

±3 g peak

± 1.9 ave

M

±7 m/s 2

XX

±.56 in.

±4.0 g

±.2 g

±2125 lb

±1.85 g

±.3 g

±1.43 g

±10 m/s2

±6750 lb

±.2 g

±170 u

±158 u

±100 u

±85 u

±1.45 g

±1.10 g

±2.30 g

±14.5 m/s 2

±725 lb

±1.45 g

±.2 g

±25 m/s 2

±29.5 u

±38 u

±11 m/s2

±1.15 g

±3.1 g peak

±2.10 ave

±6.0 m/s 2

M

XX

±.81 in.

±3.95 g

±.2 g

Xx

±2.0 g

±.3 g

±1.40 g

±8.5 m/s2

±8400 lb

±.2 g

±265 u

±242 u

±140 u

±52.5 u

±1.3 g

±1.33 g

±2.05 g

±8.75 m/s 2

XX

±2.10 g

±.2 g

±21 m/s 2

±38.5 u

±51 u

11.75 m/s 2

± 1.43 g

±3.3 peak

± 1.90 ave

±8.0 m/s 2

M

XX

±.70 in.

±4.40 g

±.2 g

XX

±2.45 g

±.3 g

±1.1 g

8.6 m/s 2

±6900 lb

±.2 g

±145 u

±125 u

±85 u

±85 u

±1.0 g

± 1.05 g

±2.2 g

±8.5 m/s2

±800 lb

±1.35 g

M

±20 m/s 2

±37 u

±42 u

±13 m/s 2

±1.95 g

±2.85 peak

±1.80 ave

8.1 m/s2

M

XX

±.63 in.

± 4.35 g

±.2 g

XX

3.23 g

±.3 g

±1.1 g

7.25 rn/s 2

±5300 lb

±.2 g

±300 u

±260 u

±80 u

±90 u

±1.25 g

±1.33 g

±2.7 g

±2.5 m/s 2

±975 lb

± 1.20 g

M

±9.25 m/s 2

37.5 u

55 u

11.5 m/s 2

±1.75 g
Table 3. (continued)

Instrument

Number

Y AXIS

8-2

7-2

26

77

18-2

57

16-2

9-2

3-1

3-6

40-2

41-2

42-2'

37-1

37-6

37-5

37-4

2-1

2-6

28

78

61

29

79

19-2

63

10-2

1-1

1-6

14

Unit of

Measure Location U.S. Stiff ANCO Bechtel Cloud KfK KWU GERB Remarks

Top of HDU

Bottom of HDU

H-2

H-2

H-2 pipe

H-2 wall

Normal tee

SP tee

BT SP tee and valve

BT SP tee and valve

Valve body

Valve CG

Valve actuator

Valve nozzle

Valve nozzle

Valve nozzle

Valve nozzle

Elbow HDU

Elbow HDU

H-6

H-6

H-6 wall

H-8

H-8

H-8 pipe

H-8 wall

Pipe dwn st reducer

EL dwn st reducer

EL dwn st reducer

Threaded rod

±2.8 m/s2

±2.25 m/s2

±M 4000 lb

±.24 in.

±.60 g

±.07 g

±.9 g

±6 m/s 2

±40 u

±35 u

±.65 g

±.65 g

±.68 g

±65 u

±25 u

M

±65 u

±35.5 u

47.5 u

±2350 lb

±.37 in.

±.l g

M

±.43 in.

±.4 g

±.l g

±6 m/s2

±50 u

±35 u

±185 u

±2.75 m/s2

±2.2 m/s2

M

±.18 in.

±.60 g

±.08 g

±.9 g

6.25 m/s2

39 u

±35 u

±.60 g

±.53 g

±.63 g

±62 u

±36 u

M

±67 u

±38 u

±55.5 u

±1575 lb

±.55 in.

±.1 g

M

±.28 in.

±i47 g

±.I g

±7.35 m/s2

±85 u

±89 u

±185 u

±2.5 m/s2

±2.2 m/s2

XX

±.4 in.

±.67 g

±.08 g

±.9 g

±13 m/s2

±34 u

±46 u

±.78 g

±.83 g

±.80 g

±102 u

±63 u

M

±102 u

±83 u

±117 u

±2000 peak

ave 600 lb

±.58 in.

M

M

±.33 in.

±.90 g

M

±9.5 mIs2

±55 u

±50 u

±210 u*

±2.6 m/s2

±2 mr/s2

XX

±.23 in.

±.68 g

±.08 g

±.9 g

±12 m/s2

±67 u

±50 u

±.95 g

±1.2 g

± 1.25 g

±85 u

±34 u

M

±90 u

±36 u

±45 u

XX

±.4 in.

±.l g

XX

±.45 in.

±.98 g

±.l g

±14 m/s2

±111 u

±115 u

±220 u

±3.10 m/s2

±2.2 m/s2

XX

±.3 in.

±.75 g

±.08 g

±.80 g*

± 15.5 m/s2

±92.5 u

±85 u

±.95 g

±.93 g

±.93 g

±50 u

±50 u

M

±122.5 u

±65 u

±95 u

XX

M

M

XX

±.45 in.

±1.35g

±.l g

±17.5 m/s2

±170 u

±185 u

±450 u

±2.25 m/s 2

±2.25 m/s 2

XX

±.43 in.

±.70 g

±.08 g

±.63 g

±10.5 m/s2

95 u

80 u

±.95 g

±.95 g

±.95 g

±71.5 u

±59 u

I

±80 u

32 u

50 u

XX

±.42 in.

±. g

XX

±.46 in.

±1.5 g

±.l g

±17 m/s2

±115 u

±155 u

±410 u

±2.75 m/s2

±2.2 m/s2

±1500 M

±.38 in.

±.65 g

±.08 g

±.70 g

±11.5 m/s 2

±65 u

±80 u

±1.3g

±1.25 g

±1.33g

±95 u

±60 u

M

±80 u

±70 u

±100 u

XX

*High energy

±.42 in.

±.l g

XX

±.43 in.

±1.0 g

±.l g

8.5 m/s2

95 u

±100 u

±195 u
Table 3. (continued)

Instrument Unit of

Number Measure

Y AXIS (continued)

20-2 A

11-2 A

34 F

81 D

36-2 A

67 A

4-1 S

4-6 S

35-2 A

50 D

Location

Pipe at thrd rod

Pipe dwn st H-10

H-12

H-12

H-12 pipe

H-12 wall

DF 16 nozzle

DF 16 nozzle

DF 16 nozzle

DF 16

U.S. Stiff ANCO Bechtel Cloud KfK KWU GERB Remarks

±1.1 g

±7.75 m/s2

±487 lb

±.39 in.

±1.15 g

±.l g

±92.5 u

±85 u

±6.5 m/s2

±.19 in.

±1.05 g

±13 m/s2

±475 lb

±.64 in.

±1.15 g

±.l g

±82.5 u

±78.5 u

M

±.17 in.

±1.3 g

±13.5 m/s2

XX

±.45 in.

±2.38

±312 u

±300 u

±5.75 m/s 2

±.16 in.

±1.3 g

±13.5 m/s2

M

±.4 in.

±2.75

±.l g

±95 u

±87.5 u

±7 m/s 2

±.18 in.

±1.5 g

±14 m/s2

XX

M

±1.8 g

±.l g

±200 u

±190 u

±6.6 m/s 2

±.18 in.

±1.23 g

± 10.5 m/s2

XX

±.38 in.

± 1.45 g

±.l g

±135 u

130 u

±7.0 m/s2

±.18 in.

±1.20 g

11.5 m/s2

XX

±.35 in.

±2.3 g

M

±100 u

±95 u

±6.5 m/s 2

±.17 in.

Z AXIS

22-2

toj 15-3

8-3

7-3

16-3

24

59

9-3

40-3

41-3

42-3

2-1

2-6

30

80

19-3

62

10-3

1-2

1-3

A

A

A

A

A

F

A

A

A

A

A

S

S

F

D

A

A

A

S

S

DF 16 body

HDU support

Top of HDU

Bottom of HDU

Normal tee

H-4

H4 wall

SP tee

Valve body

Valve CG

Valve actuator

Nozzle HDU

Nozzle HDU

H-7

H-7

H-7 pipe

H-7 wall

EL dwn st reducer

EL dwn st reducer

EL dwn st reducer

±.43 g

±1.5 g

±12 m/s 2

±4 m/s2

±1.25 g

±3500 lb

±.2 g

±6.7 m/s2

±.75 g

±.75 g

±2.0 g

±35 u

±47 u

±2750 lb

±.31 in.

M

±.2 g

± 16 m/s 2

±117 u

±77.5 u

±.39 g

±1.65 g

±11 m/s2

±4 m/s2

±1.0 g

±3500 lb

i.2 g

±4.95 m/s 2

±.5 g

±.75 g

±1.75 g

±38.5 u

±55.5 u

±1250 lb

±.35 in.

M

±.2 g

±il.5 m/s2

±72.5 u

42.5 u

±.7 g

±1.13 g

±11 m/s2

±4 m/s 2

± 1.75 g

±4000 lb

±.2 g

M

±.9 g

±1.0 g

±2 g

±81.5 u

±115 u

±1500 lb

±.35 in.

±1.28 g

±.2 g

±15 m/s2

±80 u

±55 u

±.38 g

±1.5 g

±12 m/s2

±4 mr/s2

±1.63 g*

±3750 lb

±.2 g

±7.5 m/s2

±.75 g

±.8 g

±2.5 g

±36 u

±45 u

XX

±.4 in.

M

±.2 g

±26 m/s2

±90 u

±56 u

±.42 g

±1.5 g

±11.5 m/s 2

±4 m/s2

± 1.68 g

±8000 lb

±.2 g

±6.75 m/s2

±.9 g

±1.05 g

±2.5 g

±62.5 u

±95 u

XX

±.43 in.

M

±.2 g

±13.75 m/s 2

±290 u

±190 u

±.42 g

±1.75 g

±12 m/s2

±4 mr/s2

±1.58 g

±7250 lb

±.2 g

M

±.75 g

±.75 g

±2 g

±30 u

±45 u

XX

M

±1.10 g

±.2 g

± 12.5 m/s 2

±132.5 u

±90 u

±.39 g

± 1.55 g

±1i m/s 2

±4 mr/s2

±2.2 g

±5700 lb

±.2 g

M

±.65 g

±.7 g

±2.35 g

±70 u

±100 u

XX

±.45 in.

±1.3 g

±.2 g

±6.75 m/s 2

±80 u

±51 u
Table 3. (continued)

Instrument Unit of

Number Measure

Z AXIS (continued)

31 F

20-3 P

A

Location U.S. Stiff ANCO Bechtel Cloud KfK KWU GERB Remarks

H-9

H-9

±700 lb

±.75 g

±1150 lb ±1500 lb ±950 lb

±.75 g ±1.15 g ±1.0 g

XX

± 1.88 g

±950 lb

±1.1 g

±275 lb

±1.0 g

11-3

33

36-3

66

4-2

4-3

35-3

22-3

W H-9

A

P Pipe up st H-10

A

F H-ll

±.2 g

28 m/s 2

±450 lb

±1.13 g

M

±100 u

±97.5 u

± 17.5 m/s2

±1.13 g

±.2 g ±.2 g ±.2 g ±.2 g ±.2 g

±46 m/s 2 ±55 m/s2 ±36 m/s2 ±20 m/s 2 ±30 m/s2 ±11.5 m/s2

±.2 g

±5.25 lb ± 1175 lb ±550 lb

A

A

S

S

A

A

H-Il pipe

H-lI wall

DF 16 nozzle

DF 16 nozzle

DF 16 nozzle

DF 16 body

±1.13 g

M

±117.5 u

±120 u

± 17 m/s 2

±1.13 g

±.93 g

M

±79 u

±75 u

± 18.5 m/s 2

±1.6 g

± 1.38 g

M

±108 u

±110 u

±17.5 m/s2

±1.13 g

±538 lb*

±1.6 g

M

±122 u

±138 u

± 17.5 m/s 2

± 1.39 g

±600 lb ±875 lb Support

installed

in error

±1.25 g ±1.85 g

M M

±117.5 u

±127.5 u

±17.5 m/s2

±1.4 g

±125 u

± 137 u

± 16.75 m/s 2

±1.3 g

A = Acceleration

D = Displacement

S = Strain

F = Force

m/s 2 = Meters per second square

lb = Pounds force

g = Acceleration measured in standardized gravitational units

u = Microstrain

XX = Not used in this confirmation

M = Was not recorded or would not print out after digitizing
Table 4. Peak response matrix for all support systems at 6-Hz starting frequency

Instrument Unit of

Number Measure Location U.S. Stiff Bechtel Cloud KfK KWU Remarks

X AXIS

700

703

15-1

8-1

7-1

25

76

17

56

27

18-1

58

16-1

N. (A 9-I

23

60

3-2

3-3

37-2

37-3

40-1

41-1

42-1

10-1

32

21

65

11-1

2-2

2-3

35-1

22-1

Struct bottom HDU

Struct top HDU

HDU support

Top HDU

Bottom HDU

H-l

H-l

H-i pipe

H-l wall

H-3

H-3 pipe

H-3 wall

Normal tee

SP tee

H-S

H-5 wall

Pipe bt H-5 and valve

Pipe bt H-5 and valve

Valve nozzle

Valve nozzle

Valve body

Valve CG

Valve actuator

EL dwn st reducer

H-10

H-10 pipe

H-10 wall

Pipe upst of H-10

DF 16 nozzle

DF 16 nozzle

Nozzle DF 16

Body DF 16

±1.5 m/s 2

±2 mls2

±2.5 g

±6 m/s2

±3.5 m/s2

±2500 lb

±.70 in.

±4 g

±2.1 g

±1800 lb

±2.75 g

±.24 g

±2.4 g

± 16.5 mls2

±4750 lb

±.2 g

±320 u

±270 u

±135 u

±110 u

±2.1 g

±1.85 g

±2.5 g

±22 m/s 2

±1300 lb

±1.20g

±.2 g

±30 m/s 2

±40 u

±55 u

M

±1.55g

±1.7 m/s 2

±2 mns2

±2.6 g

±6.75 mns2

±3.5 m/s2

±1400 lb

±.75 in.

±2.85 g

±.21 g

±3150 lb

±2.25 g

±.24 g

± 1.55 g

±10 m/s2

±9250 lb

±.2 g

±300 u

±250 u

±125 u

±65 u

±1.85 g

±1.58 g

±2.8 g

±12 m/s 2

±1300 lb

±1.10g

±.2 g

±40 m/s2

±47 u

±71 u

M

±1.85

±1.7 m/s2

±2 m/s2

±2.40 g*

±6.9 m/s 2

±3.5 m/s 2

±.74 in.

4.5 g

±.21 g

1.75 g

±2.4 g

1.53 g

15 m/s2

± 1 1000 lb

±.2 g

200 u

±180 u

±117 u

±75 u

±1.84g

±1.20 g

±2.5 g

±16 m/s 2

±1050 lb

±1.40 g

±.2 g

±28 m/s2

±36 u

±40 u

M

M

±1.7 m/s 2

±2 m/s 2

±2.5 g

±7 m/s 2

±3.5 m/s 2

±.58 in,

±5 g

±.28 g

±1.85 g

±.24 g

±1.25 g

±9.5 m/s2

±7750 lb

±.2 g

175 u

150 u

±75 u

±65 u

±1.15 g

±1.1 g

±1.85 g

1 1 W/S2

XX

3.05 g

±.2 g

±19 m/S2

38 u

50 u

M

±3 g

±1.7 m/s 2

±2 m/s 2

±2.4 g

±7 m/s2

±4 m/s 2

±.6 in.

±5.5 g

±.25 g

±2.10 g

±.25 g

±1.8 g

13 m/s2

±11500 lb

±.2 g

260 u

225 u

±120 u

±75 u

±1.60g

1.50 g

±2.45 g

15.5 m/s 2

± 1050 lb

1.15 g

±.2 g

±23.5 m/s 2

50 u

68 u

M

±2.55 g
Table 4. (continued)

Instrument Unit of

Number Measure Location U.S. Stiff Bechtel Cloud KfK KWU Remarks

Y AXIS

701

704

8-2

7-2

26

77

18-2

57

16-2

9-2

3-1

3-6

40-2

c0 41-2

42-2

37.1

37.6

37.5

37-4

2-1

2-6

28

78

61

29

79

19-2

63

10-2

1-1

1-6

14

Struct HDU

Struct HDU

Top HDU

Bottom HDU

H-2

H-2

Pipe H-2

H-2 wall

Normal tee

SP tee

BT SP tee and valve

BT SP tee and valve

Valve body

Valve CG

Valve actuator

Valve nozzle

Valve nozzle

Valve nozzle

Valve nozzle

Elbow HDU

Elbow HDU

H-6

H-6

Wall H-6

H-8

H-8

Pipe H-8

Wall H-8

Pipe dwn st reducer

El dwn st reducer

El dwn st reducer

Threaded rod

±.5 mrns2

±.5 m/s2

±1.75 mis2

± I mis

2

±5000 lb

±.2 in.

±.82 

g

±.05 

g

±.85 

g

±7 m/s

2

MM

±.65 

g

±.60 

g

±.63 

g

±115 

u

±40 

u

±10 

u

±125 

u

±40 

u

±60 

u

±2750 lb

i.18 in.

±.l 

g

M

±.45 in.

±.58 

g

±.l 

g

±7.5 mis

2

±80 

u

±65 

u

±225 

u

±.5 mls

2

±.5 mis2

±2 mis

2

±1.5 mis

2

±.2 in.

±.75 

g

±.05 

g

±.78 

g

±7 mis

2

MM

±.65 

g

±.63 

g

±.63 

0

±80 

u

±59 

u

± 17.5 

u

±112.5 

u

±62.5 

u

±82.5 

u

±1100 lb M

±.l 

g

MM

±.65 

g

±.l 

g

±8 mis

2

±80 

u

±60 

u

±275 

u

±.5 mis

2

±.5 mis

2

±1.75 mis

2

±1.2 mis

2

±.2 in.

±.95 

g

±.05 

g

1.02 

g

±9.5 mis

2

MM

±.75 

g

±.75 

g

±.80 

g

±75 

u

±58 

u

±23 

u

±110 

u

±40 

u

±50 

u

XX

±.3 in.

±.l 

g

xx

±.4 in.

±.75 

g

±.l 

g

±9 mis

2

±95 

u

±100 

u

±338 

u

±.6 mis

2

±.5 ml/s2

±3 mis

2

±1.75 mis

2

i.18 in.

±.8 

g

±.05 

g

±.8 

g

±8 mis

2

MM

±.63 

g

±.60 

g

±.65 

g

±60 

u

±36 

u

±15 

u

±68 

u

±43 

u

±60 

u

XX

±.5 in.

±.l 

g

XX

±.4 in.

±.73 

g

±.l 

g

± 10 mis

2

±115 

u

±102 

u

±275 

u

±.6 mis

2

±.5 mis

2

±2.25 m/s2

±1.6 m/s

2

±.26 in.

±.85 

g

±.05 

g

±.85 

g

±8 mis

2

MM

.53 

g

±.54 

g

±.60 

g

±73 

u

±59 

u

±22 

u

±105 

u

±60 

u

±78 

u

XX

±.5 in.

±.l 

g

XXM

±.70 

g

±.l 

g

±11.5 m/s

2

±79 

u

±110 

u

±300 

u
Table 4. (continued)

Instrument Unit of

Number Measure Location U.S. Stiff Bechtel Cloud KfK KWU Remarks

Y AXIS (continued)

20-2

11-2

34

81

36-2

67

4-1

4-6

35-2

50

22-2

Z AXIS

702

4 705

15-3

8-3

7-3

16-3

24

59

9-3

40-3

41-3

42-3

2-1

2-6

30

80

19-3

62

10-3

1-2

Pipe at thrd rod

Pipe dwn st H-10

H-12

H-12

H-12 pipe

H-12 wall

DF 16 nozzle

DF 16 nozzle

DF 16 nozzle

DF 16

DF 16 body

Struct bottom HDU

Struct top HDU

HDU support

Top HDU

Bottom HDU

Normal tee

H-4

H-4 wall

SP tee

Valve body

Valve CG

Valve actuator

Nozzle HDU

Nozzle HDU

H-7

H-7

H-7 pipe

H-7 wall

El dwn st reducer

El dwn st reducer

i1.25 g

±17.5 ms5

2

±600 lb

±.4 in.

±1.5 g

±.l g

M

±60 u

M

±.17 in.

±.66 g

±1.65 m/s 2

±2.1 m/s 2

±1.33 g

±7 ml/s2

±2.75 MI/s2

±2.35 g

5350 lb

±.2 g

±10 m/s2

± 1.33 g

±1.15 g

±2.43 g

M

M

M

±.35 in.

±.2 g

±20 m/s 2

±135 u

±1.35

± 18 M/s2

XX

±.24 in.

±2.2 g

±.1g

M

±250 u

M

M

±.75 g

±1.65 m/s2

±2.1 m/s2

±1.38 g

±9 m/s2

±3.5 m/s2

±2.0 g

±5000 lb

±.2 g

±8.5 m/s2

±.85 g

±.85 g

±2.05 g

M

M

±1700 lb

M

M

±.2g

±19.5 M/s2

±115 u

±1.45 g

±20 m/s2

XX

M

±2.1 g

±.l g

M

73 u

M

M

±.68 g

±1.65 m/s2

±2.1 Mr/s2

±1.2 g

±9 Mrns2

±3 m/s2

±1.98 g

±6750 lb

.29

±8 MIs2

±1.0 g

±98 g

±2.45 g

M

M

M

±42 g

±.2 g

37.5 mrS/2

±135 u

±1.85 g

±17.5 MI/s2

XX

±.4 in.

±1.65 g

±.1 g

M

±243 u

M

±.08 in.

±.66 g

±1.65 m/s2

±2.1 m/s2

±1.25 g

±8.5 m/s2

±2.5 m/s 2

±1.9 g

±5750 lb

±.2 g

±8 mIs2

±.85 g

±.75 g

±1.9 g

M

M

±.3 in.

±.2 g

±12 mr/s2

405 u

± 1.55 g

± 12.5 m/s2

XX

M

±1.6 g

±.l g

M

±115 u

M

±.06 in.

±.75 g

±1.65 m/s2

±2.1 MI/s2

±1.38 g

± 8.25 m/s 2

±2.5 m/s2

± 1.85 g

±7200 lb

±.2 g

±8 m/s 2

±.9 g

±1.0 g

±2.0 g

M

M

±.60 in.

±.2 g

13.5 m/s 2

±140 u

Peak
Table 4. (continued)

Instrument Unit of

Number Measure Location U.S. Stiff Bechtel Cloud KfK KWU Remarks

Z AXIS (continued)

1-3

31

20-3

64

11-3

33

36-3

66

1-j 4-2

4-3

35-3

22-3

S

F

A

A

A

F

A

A

S

S

A

Ac

El dwn St reducer

H-9

H-9 pipe

H-9 wall

Pipe up St H-10

H-l I

H-li pipe

DF 16 nozzle

DF 16 nozzle

DF 16 nozzle

DF 16 nozzle

DF 16 body

±80 u

±1400 lb

±1.15 g

±.18 g

±45 m/s 2

±675 lb

±1.45 g

±.18 g

M

±87 u

M

±1.3 g

±67.5 u

±1575 lb

±1.0 g

±.18 g

70 tn/s 2

±1100 lb

±1.45 g

±.2 g

M

±90 u

M

±1.65g

±95 u

±1050 lb

M

±.18 g

45 m/s 2

±800 lb

±29 g*

±.2 g

M

±105 u

M

±1.6g

280 u

XX

±1.88 g

±.l8 g

±28 m/s 2

XX

±2.85 g

±.18 g

M

350 u

M

±2.15 g

±80 u

± 1000 lb

± 1.05 g

±.18 g

38m nls2

±750 lb

±1.65 g

±.2 g

M

±158 u

M

± 1.95 g

Impact

mr/s =

8=

lb =

u=

XX =

M=

Acceleration

Displacement

Strain

Force

Meters per second square

Acceleration measured in standard gravitational units

Pounds force

Microstrain

Not used in this configuration

Was not recorded or would not print out after digitizing
Force pin Displacement transducer Accelerometer

Figure.. F.orce,.splaement........ ....... . a acelraio .......

l,40tl~~~~~t ,.t..!t,.,ot,,,J,;a~~~~~~~~~~~~~akL, l..fl,,x~~~~~f,,,t,. ait..Ri1 telt ,t~~~~~~~~~~~hl.,:l~~~~nl, Ill,8liblI~~~~~~~~d~i 4A 1,1.l; A Il~~~~~~~i.I:I,;I~~~~~u <1;1,ll3,l ddlil~~~~~~~~~lltillt~~~~vitil tI~~~~~t,,J~~~lI,{.I\.,I25, I iltI'd 0 ll ltit0 OR t\5 Ll\ i

Figure 33. Force, displacement, and acceleration instruments.

3000

a

0

LL

-4

0)

*° 02 2

0-

0

- 2

Time (s) Time

(a) Force (c) Pipe acceleration

r: 2.74 .z_

C

'1 2.31

E

a)

CZ 1.87

0.5 1 AA

0.6

-0.4

C Li

.2 0.2 M &-I I I I Ia, 0 1

- 0.2

-0.4

104.99 116.99 128.99 140.00 152.99 164.99 104.99 116.99 128.99 140.99 152.99 164.99

Time Time

b) Displacement (d) Wall acceleration 9.0647

Figure 34. Responses recorded at Pacific Scientific snubber location H-i during Test T40.30, 8-Hz starting frequency.

29
1200

800

n 400

0

0 0 IL

-400

onn

I I I I I =11 'vI'il I I

2.50

-a 1.50 LJJ

o_ 0.50 II4I11

00

0)

z~ - 0.50

- 1.50

F_ I i I I I I

I II I 1

1 C

I I II I I I Ii I I II_ I I_ I_ I

I I I I I I

104.99 116.99 128.99 140.99 152.99 164.99

Time

(a) Force

-2.50 _1 i l l i 1 i I l l

104.99 116.99 128.99 140.99 152.99 164.99

Time

Pipe acceleration

-1.04 _ I = = = = = = = = = aill ad 1 l Ali:ar ..I.v v. .o _4

C

a1) E0

0

CL

C,)

a

0.52

0

-0.52

1.04

-1.56

104

0

C.

II I I I I I

.99 116.99 128.99 140.99 152.99 164.99

Time

(b) Displacement

Figure 35. Responses recorded at Pacific Scientific snubber

by the Celesco displacement transducers described

previously.

We conducted a posttest investigation at the INEL

dynamics laboratory to determine if the Pacific Scientific snubbers were allowing displacements larger

than the 0.1-in. peak-to-peak dead band specified

by the manufacturer. A complete report of this investigation is included in Appendix C (Volume 2). The

investigation indicated that the large displacement

readings were a product of the Celesco transducers

rather than the actual movement of the piping. The

spurious transducer readings were probably a result

of cable whip.

3.4.2 Performance of the Bergen Paterson

Hydraulic Snubber. Prior to installation in the

HDR, the Bergen Paterson hvdrau'li 'smnhher had been

exposed to several seismic experiments at the INEL

and was considered a functionally aged unit. Functionally, there was no problem with the unit during the

test program, and there was no observed leakage. The

large displacements recorded during the testing were,

again, a product of the Celesco transducer.

0.30000 l l l - l l

0.20000...

0.10000...

0 "

-0.10000......-

-0.20000 - - - 1- -

104.99 116.99 128.99 140.99 152.99 164.99

Time

(d) Wall acceleration

9-0643

ion H-12 during Test T40.30, 8-Hz starting frequency.

4.3 Performance of Snubber Replacement

evices. Section 2.3 gives a description of the four

ping support systems that used snubber replacement

-vices. We expect that EPRI and ANCO will evaluate

eir systems' performance against the performance of

e typical snubber system (U.S. stiff system), and use

e results, and other testing, to justify the use of the

,vices as replacements for snubbers in utilities. Since

e GERB Company is primarily concerned with the

aropean market, and the ANCO device is built using

e GERB viscous mass device as its base and is exected to be the only GERB device potentially to be

arketed in the U.S., the GERB system results will

)t be specifically discussed in this report.

The EPRI-sponsored devices and those built by

NCO have common features yet very diverse designs.

i1 are meant to be pin-to-pin replacements for snubers; all work on energy absorbing principles; and all

re designed with the intention to provide higher

liability than conventional snubbers.

The EPRI/Bechtel device is based on the principle

.'dynamic energy absorption by ductile flexures. The

PRI/Cloud device is based on the principle of energy

k

30
absorption by impact, where the impacting takes place

inside the device. During the SHAG test, the pipe

behaved in a manner similar to the way pipes behave

at common box beam supports. The ANCO device is

based on the GERB viscous mass energy absorber.

Figure 36 is a photograph of the EPRI/Cloud devices

installed at locations H-7 and 8; Figure 37 is a functional schematic of the EPRI/Bechtel device; Figure 38

is a photograph of the ANCO device installed at

location H-2.

Cloud and Bechtel devices were installed individually

for tests at the three significant starting frequencies.

ANCO installed their support system for one test at

8 Hz, but did not participate in the 4.5- or 6-Hz frequency tests.

Only a general qualitative discussion can be presented for the snubber replacement devices, because

the only analyses made compared the total system

response for each support system methodology.

In general, the load ratings for all of the snubber

Inspection

attachment /opening

slot A

x-shaped view Side Typical x-shaped Sdviwx-shaped

plates s plate

Section attachment

Schematic

Energy absorber 7-8773

Figure 37. Functional schematic of the EPRI/Bechtel energy

absorber.

^

Figure 36. EPRI/Cloud seismic stops installed at locations

H-7-8.

Figure 38. ANCO snubber replacement device installed at

the H-2 location.

31
replacement devices were higher than the loads reached

in the tests. Therefore, no damage was expected for

any of the devices, and none was sustained. Research

being performed for EPRI by Cloud and Bechtel is

expected to detail the performance of their units, and

ANCO Engineers have published reports on their

findings. The following section presents a comparison

of the piping support systems, including the four

systems that used snubber replacement devices, and

explains how modifications to the support system

affected VKL response.

3.5 Comparison of Piping

Support Systems \\ The dynamic loading from the shaker exceeded

design allowable strain limits for the concrete containment building. The VKL piping acceleration responses

averaged from 1 to 3 g throughout the piping system.

Some of the installed snubbers experienced loads

approaching ASME code Level C allowables. Struts

experienced loads of up to 11,000-lb force. However,

the strains measured in the piping system and valve

were fairly low in comparison to the forces and accelerations experienced in each of the piping support

A d systemtested. of the

d alve as not oone of the support

systemresulted in piping strain measurements that

reached 50% of yield.

The responses were high enough to permit identification of distinct modes of response for the various piping

support systems and to assess their performance. The

U.S. stiff system performed as designed, raising the

resonant frequency of the piping system. Generally,

the flexible and U.S. stiff system responses did envelop

the response of the VKL. However, they were not the

best support systems based on stresses in the system.

The KWU system had fewer high-peak responses than

did either the stiff or the flexible system. This fact supports current thinking in the United States that the best

design lies somewhere in between stiff and flexible.

Table 5 compares the forces and strains for the U.S.

stiff snubbed, Cloud, and Bechtel piping support systems, the recorded measurements being average peak

responses from the measured histories. The measurements include only those instruments that were used

in all three support systems. The comparison shows

that whereas the snubbed system has four of the highest

measured values for a given location, the magnitudes

are close to those of one or both of the other systems;

however, several of the Cloud and Bechtel measurements are double those of the snubbed system

responses. The snubbed system had 4 maxima of the

22 selected measurements, 3 of them for the 6-Hz

starting frequency. The Cloud system had 8 maxima,

5 of them for the 6-Hz starting frequency. The Bechtel

system had 11 maxima, 7 for the 8-Hz starting

frequency.

These results point out that changing pipe support

types changes the response of a piping system when

all other parameters remain the same. The results of

the changes are not always beneficial, as shown. The

ANCO system was tested only at the 8-Hz starting frequency and at ambient temperature. The ANCO pipe

support system was stiffer than the U.S. stiff system,

as indicated by evaluation of the measured responses.

The ANCO system had typically lower forces and

strains than the U.S., Bechtel,. and Cloud systems.

However, the ANCO system was tested only at the

8-Hz shaker starting frequency and, like the U.S.

system, might have responded more at the 6-Hz starting frequency (see Section 3.3). The ANCO system

was tested only with the piping system at ambient

temperature. The containment environment was

warmer when the piping system was at elevated temperature, and the high temperature might have lowered

the viscosity of the viscous damper had it been tested

at a higher temperature. Therefore, a direct comparison

of the responses of a typical U.S. stiff system with

those of the ANCO system cannot be made.

Each of the four energy-absorbing support systems

resulted in different response frequencies in the piping.

Also, the expected plant-specific input spectra must be

considered when judging the effectiveness of the support system in reducing loads in the piping. We infer

from the results of the SHAG experiments that one

system cannot be chosen over another without careful

consideration of the input excitation to the piping

system. It anpears that appropriate analyses should be

conducted before snubbrineitn uptsyem

are replaced with snubbu .

Posttest analyses of the KfK flexible and U.S. stiff

system responses indicated, as would be expected, that

stiff system dynamic response stresses were less than

the corresponding flexible system stresses. However,

the relative differences were not as great as would be

expected. The moderately flexible KWU system, with

50 % fewer supports than the typical U.S. stiff design,

responded with a smaller total system stress than any

of the other systems tested, including the energyabsorbing systems.

In general, if piping system dynamic input is significant and input excitation frequencies correspond with

the natural frequencies of the piping system, the response of the system will be amplified. The philosophy

underlying present U.S. nuclear piping system seismic

design is to avoid amplification and reduce resonant

response by using snubbers and struts to stiffen the

systems so that the natural frequencies are higher than

32
Table 5. Comparison of system device forces and strains for different support

configurations

Instrument

No.

X AXIS

27

27

23

23

3-2

3-2

3-3

3-3

32

32

Y AXIS

1-1

1-1

1-6

1-6

14

14

Z AXIS

24

24

31

31

33

33

Unit

of Measure

,lb Force

lb Force

lb Force

lb Force

Micro Strain

Micro Strain

Micro Strain

Micro Strain

lb Force

lb Force

Micro Strain

Micro Strain

Micro Strain

Micro Strain

Micro Strain

Micro Strain

lb Force

lb Force

lb Force

lb Force

lb Force

lb Force

Location

H-3

H-3

H-5

H-5

Pipe Between Tee & Valve

Pipe Between Tee & Valve

Pipe Between Tee & Valve

Pipe Between Tee & Valve

H-10

H-10

El Below Reducer

El Below Reducer

El Below Reducer

El Below Reducer

Threaded Rod

Threaded Rod

H4

HA4

H-9

H-9

H-lI*

H-Il

- Shaker

Starting

Frequency

(Hz)

8

6

8

6

8

6

8

6

8

6

8

6

8

6

8

6

8

6

8

6

8

6

U.S.

Stiff

Snubbed

System

2400

1800

8000

4750

180

320

160

270

750

1300

50

80

35

65

185

225

3500

5350

700

1400

450

675

Bechtel

System

3125

3150

7500

9250

370

300

330

250

825

1300

55

80

50

60

210

275

4000

5000

1500

1575

1175

1100

Cloud

System

2125-a

6750

11000

170

200

160

180

725

1050

110

95

115

100

220

338

3750

6750

950

1050

550

800

a. Measurement not available.

the amplified building excitation frequencies. This

design philosophy has disadvantages. Thberclai4ve

mnement of the anchors in a stiff support system can

aaly ad stress to a piping system during a seismic

event, and stresses caused by thermal expansion during normal operation may be large, especially if snubbers malfunction by locking up when they should not.

The following "time at frequency" rationale may

explain why the moderately flexible KWU system

experienced lower total system stresses than the U.S.

stiff system. The test excitation method, a decaying

sinusoidal input to the. HDR building, ensured that,

with the exception of the very flexible system, the

lowest natural frequencies of all systems were excited

with large input frequency content, and the systems

with lower natural, frequencies were excited with

greater energy. However, the time required for maximum resonant response to be generated in the piping

system is largely dependent on the natural frequency

of the excited mode: the lower the natural frequency,

the longer the time required to obtain maximum

response. Apparently the duration of excitation was not

long enough for the lower frequency modes of the

moderately flexible KWU system to reach maximum

response. This would explain why the moderately stiff

system developed lower total system stresses than the

U.S. stiff system even though the U.S. stiff system had

the highest natural frequencies and would therefore be

expected to respond with less amplification. We believe

that this result is valid for systems subjected to true

33
earthquake excitation as well; because of complex

building response filtering imposed on the system by

the test, the excitation frequency content was very

"earthquake-like," and the duration of maximum

excitation, approximately 30 s, was conservatively

representative of the duration of earthquake strong

motion.

Further analysis of experimental results is needed,

since the conclusions presented here are based on

limited data analyses. However, these analyses results

suggest the advantages of more flexible designs for

U.S. nuclear piping systems.

X

z

3.6 Valve and Motor Operator

Response

One of the objectives of the HDR testing was to subject the refurbished 8-in. motor-operated gate valve to

combined loads. The valve was tested under normal

internal hydraulic loads (pressure and flow loads) in

combination with dynamic excitation to determine how

effectively the normal equipment qualification single

effects testing used in the U.S. can model or envelope

in situ conditions. Tests were conducted both at ambient and at elevated temperatures.

The valve was baseline functional tested at the INEL

with and without pressure loads prior to its use in the

SHAG dynamic test series. Important valve parameters

were recorded at that time, including valve stroke time,

motor current and voltage, system pressure, valve differential pressure, valve stem position and strain, and

system fluid temperature. Similar baseline functional

tests, with the addition of flow loads, were performed

after the valve was installed in the VKL at the HDR.

Those tests were performed at ambient temperature just

before the SHAG dynamic testing and again at elevated

temperatures (200'C) just before the hot dynamic tests.

These pretest parameters were compared with parameters recorded during pre-SHAG functional testing.

From the quick look data, satisfactory agreements were

obtained.

Dynamic testing of the valve consisted of opening

and closing the valve during and after the simulated

seismic excitation of the piping system. Dynamic tests

were conducted both at ambient and at elevated temperatures with the valve subjected to various pressure

and flow loads. The same parameters recorded during

the baseline functional tests were recorded during the

dynamic tests. In addition, acceleration, displacement,

and strain were measured on the valve to record its

response to dynamic excitation. Figure 39 shows the

valve instrumentation, and Figure 40 shows the installed valve.

©

Valve

(

Strain

guage

type

Strain guage

a4-0

4-0

n(

Legend

Accelerometer and its detection axis

Single strain guage and its detection axis

Strain guages (see strain guage detail)

Displacement guage

nI Pressure

EE AP

in Valve po.

Q Valve cui

[J Valve vol

M Temperat

sition

rrent

tage

ure

Figure 39. Valve instrumentation detail.

34
3.6.2 Valve Response. The valve subassembly

performed quite well throughout the test program, as

determined from the posttest data review and analysis.

None of the data provides any indication of measurements different than they should be for the given test

conditions and loading. The valve stem packing was

replaced during refurbishment at INEL, and no packing leakage was observed during the test program.

The dynamic excitation experienced by the valve did

not adversely affect its operability. In fact, the closing currents recorded during the hot dynamic tests were

lower than those recorded during the hot functional

tests (which were conducted without dynamic input to

the system), indicating that the load was actually

smaller. We assume that the vibration during the

dynamic tests helped to break the valve disc to body

guide friction.

3.6.3 Performance of the Motor Operator.

Table 6 gives a summary of the measurements taken

of valve functions during the SHAG tests. From the I

column labeled "stall," one can see that the motor

operator failed to torque out at the end of the closing

stroke during several of the tests. This anomaly is

discussed at length in the following paragraphs.

Initially, the motor operator appeared to perform

quite well. The stroke times and valve currents varied

with internal valve loadings as expected, with the

exception of the slower closing times during hot functional tests. They are slower than the closing times during hot dynamic test. The seismic excitation caused no

measurable increase in operator load and may have

actually reduced that load in some cases. The spread

of valve functional responses (current and stroke times)

was very good. The failure of the operator to torque

out is apparently unrelated to the dynamic loads imposed on the valve during the tests.

3.6.3.1 Torque-out Failure. Normally, the high torque

produced by the motor when the valve reaches the fully

closed position causes the motor operator to torque out;

that is, the closing torque switch opens and, through

the motor controller, interrupts current to the motor.

Figure 41 shows the major components involved in this

process. The splined output shaft drives the worm,

which turns the worm gear and the stem nut. The stem

nut drives the threaded valve stem. As the valve seats

and the worm gear resists motion, the worm climbs

the worm gear, floating on the splined shaft and compressing the torque spring until the shoulder of the

worm contacts and rotates the arm of the torque switch

and opens the torque switch. The higher the torque

switch setting, the further the worm must compress the

current to the motor. If the torque switch fails to open,

Figure 40. Installed gate valve and part of the installed

instrumentation.

A motor-operated valve consists of two subassemblies: the valve itself and the motor p r.

In the following discussion, Section 3.6.1 reports

on the structural integrity of both the valve and

motor operator subassemblies. Section 3.6.2 reports

on the operability of the valve subassembly, and

Section 3.6.3 reports on the performance of the motor

operator and documents the operator's anomalous

performance. Section 3.6.4 reports the valve's (and

the operator's) amplified dynamic response to the

tests.

3.6.1 Structural Integrity of the Motor-Operated

Valve. The structural integrity of the valve and

motor operator was not affected by SHAG dynamic

excitation. tl rge. exctaion Sructurallyvalves are inherently ruggedp

From the loadings input at HDR and the strains

measured during the tests, we infer that considerably

higher loadings could have been applied without

reaching near yield stresses of the valve and motor

operator.

35
Table 6. Valve function parameters

Current in Amps

Test

T40

Ambient

34

35

36

37a

b

40a

b

20a

b

60a

b

50a

b

70a

b

10a

b

30a

b

31a

b

41

21

11

51a

b

Hot a

Func b

52a

b

32a

b

42a

b

12

22

12A

14

16

13

After a

Hot b

Temp

(OC)

20

20

20

20

20

20

20

20

20

20

20

20

20

20

20

20

20

210

210

210

210

210

50

210

40

Stroke Time (s) Closing

Closing Opening Run Peak

Opening

Stall Peak Run

Pressure (psi)

System AP

14.4

15.5

17

15.5

22

22

20

19.5

20

14.4

14.7

15

15.5

15.5

15.6

17

16

15

16

16

16

16

16

16

16

14

17

12

12

12.5

12.5

12.5

12.5

12.5

12.5

13.5

12.5

14

12 12+

12 14

12.5 15

11 13.5

12 13.5

11.5 -

12 17

12 -

13.5 18

12.5 16

14 19

13.5 -

12.5 14

11 -

11 13

11.5 -

12.5 _

12.5 -

12.5 -

12.5 13.5

12 13

12.5 13

12.5 -

12.5 -

17 27

17 27

12.5 25

12.5 25

12.5 25

12.5 26

12.5 25

13.5 25

13 25

13 25

10 17

- 16.41

- 17.67

- 17

_ 14

- 17

35 13

- 17

38 20

- 24

38 25

- 23

- 20

38 20

- 19

37 18

- 24

38 25

- 25

38 25

- 25

38 25

- 25

- 25

- 25

38 25

37 25.5

40 12

38 12

37 10

36 10

37 10

36 11

36 10.5

37 10.5

38 11

- 18

37 10

- 17

10.94

10.6

11

9.5

11

10

10

9

12

12.5

11

9

9

7

7.5

8

10

10

10

11

11.5

11.5

10.5

11.5

11

11

7

7

6

7

5

6

5

6

6

7

5.5

8

73.95

73.95

15.0

55.5

67

67

74

74

67

67

70

70

70

70

70

70

70

924

924

924

924

924

70

924

50

384

377

333

330

333

259

371

344

351

340

344

333

263

333

263

362

329

362

340

348

333

333

325

329

322

333

313

313

301

301

301

301

305

305

305

359

313

350

359

354

Valve tests were not performed during this dynamic test.

Valves tests were not peformed during this dynamic test.

40 14.5 14 13 19 - 20 12

1 1

74

- 15 14 13 19 41 22

36
Torque switch 9-3W5

Figure 41. Simplified diagram showing some of the components of a motor operator.

the motor stalls and starts to overheat. If the thermal

overload relay malfunctions, or if it has been bypassed,

the result can be motor burnout and the functional loss

of the valve.

The sequence of valve operation at the HDR required

the valve to be closed for no more than 10 s to accommodate system pressure control concerns. The reopening of the valve within 10 s after closing kept the motor

from overheating and delayed detection of the problem

until posttest data reduction. Figure 42 shows the output of the valve stem position transducer for two partial valve cycles during the fourth SHAG test (the first

observance of the malfunction). Figure 43 shows the

valve operator motor current history for the same test.

Figure 43 shows that the motor operator performed

normally during the first cycle, but during the second

cycle the torque switch did not open, and the motor

stalled.

This functional anomalv occurred repeatedly throughot ro_ . We determined early in our investigation that the problem was not caused by the torque

switch being set too high. Further analyses of the

measured valve response data from the SHAG tests indicated that the valve functional anomaly probably was

the result of more than one problem. The NRC and

the INEL agreed to set up a review group to advise

the further investigation and analyses of what might

be a generic problem. The review group included

representatives 7romT ie NRC staff, INEL, Oak Ridge

National Laboratory (ORNL), and Limitorque.

3.6.3.2 Additional In Situ Tests at HDR. The review

group recommended that a parametric in situ test be

conducted at the HDR to provide additional data.

Limitorque agreed to support the tests from its European office. Table 7 provides the results of those tests.

These results showed that the functional anomaly was

influenced by the internal valve hydraulic load. With

internal static pressure alone, the valve functioned correctly. Figure 44 shows three valve stem position

histories for the closing stroke for three internal valve

static pressures. The plot shows linear closing response

for the valve on each trace with a slightly longer total

stroke time for each increasing pressure. Figure 45

shows the same three static pressure cases with flow

through the valve. The flow and resulting differential

pressure are the same for all three of the static

pressures. In all three cases, the valve closure rate

37
9

7 - Porticlyt o en

at start ofest Relosi

// ReopenC

QL / /Opening

> 3 f oequalu to1 0 / 

coX fully closed / \ osed \ > valve position lo/

Stcrt of dyncrnic transient

69.92 81.92 93.92 105.92 117.92 129.92

Time MGHDt3SS

Figure 42. Valve position versus time during in the fourth test.

Motor goes to Power is cut off maudly std current to prepare for reopening

45- X _

Normad

Valve energized Normal Norad in r

to dose in rush in rush

35- ______ Nndrunning current 0/Valve should Norrrd peck

\rm~ ru-ning crent valhave torqued opening current \ \Norrnd mNorml pedc out here

closing opening current

torque

25 ~~~~~out

cEIrent Nor"

Openiing rml - ~~~~~~~~~~~~~~rurnning ctrrent

C ~~~~~~~~~~~~~cu-rent ~15

Cosed Valve is

energized Vale eegizedenrid

s to open todose_ to open

LMonLuoly stopped in

partially open position

-5- I

69.92 81.92 93.92 105.92 117.92 129.92

Time M0154

Figure 43. Valve current versus time during the fourth test.

38


slows down near the end of the stroke, and in all three

cases the valve does not completely close. The extent

to which the valve remains open is increasingly greater

with each increase in pressure combined with the flow

load. The static pressures applied at the HDR were all

lower than design specifications for this 900-lb valve,

and the differential pressure loads were only a small

percentage of design specifications.

The parametric study showed that at lower torque

switch settings the torque switch functioned, but the

valve did not completely close at the higher pressures

and flows. At higher torque switch settings the motor

stalled. The valve closed farther with the higher setting, but the motor usually stalled before the valve was

completely closed.

During the parametric study, we determined that the

problem was not the result of inadequate lubrication,

worn bearings, or high resistance in a field coil in the

motor. At the end of the parametric in situ study, the

cause of the problem had not been isolated. Voltages

and currents during HDR tests were measured at the

motor with three different measurement systems from

two different laboratories. According to the data, the

voltage at the motor did not drop below 107 Vdc at

motor stall, and the motor voltage at stall was only

slightly less than the running voltage. These voltage

readings temporarily diverted our attention from the

possibility that the power supply or power cabling

might be the cause of the reduced performance at HDR.

Later analyses showed that these voltage readings were

unreliable because of the circuit design.

3.6.3.3 Dynamometer Testing at Limitorque Laboratories. The motor operator was removed from the

valve and returned to the U.S. for testing at the

Limitorque Facility in Lynchburg, VA. The results of

those dynamometer tests are presented in Table 8.

Testing of the motor operator on the Limitorque

dynamometer showed a marked improvement in performance at loadings above 35 amp. Locked rotor

currents were 75 amp, compared to 50 amp at HDR.

The published locked rotor current for the motor is

120 amp.

The tests also provided some insights on the torque

switch position versus our power torques at HDR. The

torque switch was set at the nominal value of 3. A

true switch setting of 3 shod p rodc nerl

12,000 lb of thrust- the dynamometer tests showed that

at a torque switch setting of 3 the motor operator produced only 8,000 lb of thrust. A setting of 3.75 was

necessary to consistently achieve an output thrust of

12,000 lb.

3.6.3.4 Torque Spring Inspection. At the recommendation of the review group, the torque spring was

removed from the operator and inspected. We discovered that the torque spring had taken a permanent

set, measuring approximately 1/2 in. shorter than

specitied. The shorter torque spring required the torque

switch to be set to a value of 3.75 to produce the

specified torque for the nominal torque switch setting

of 3. A second Shippingport valve in the as-removed

condition was located at Oak Ridge National Laboratory. The motor operator was disassembled and the

torque spring removed for measurement. This spring

also was short, by 3/16 in. Two springs are not a large

sample, but these instances do suggest that the SMA

coil springs may he susceptible to permanent set over

time, and users should not rely on torque switch settings alone (NRC Info-rmation Notie 69-4:).

3.6.3.5 Dynamometer Testing at Peerless. The motor

manufacturer reed to dynamometer test the motor to quantify the motor-alone performance. During these dynamometer tests, the motor

met all of the specified output parameters, including

a locked rotor current of approximately 120 amp.

Figure 46 compares the actual speed and current to

predicted motor performance. We attributed the difference between the test results at Limitorque for the

motor operator and those at Peerless for the motor

alone to a difference in the test techniques, partly

because of the way the INEL had requested them to

perform the dynamometer test loadings. We had requested at both laboratories that the load be slowly

increased to the specified test load as it would in the

closing cycle of a valve. This type of load tends to heat

the motor. Because the specified performance was for

a relatively cool motor, the motor was cooled to ambient temperature before each test at Peerless. This was

not done at Limitorque.

To quantify the effects of motor heating, a special

test was performed during the electric motor dynamometer test. A 50 ft/lb load was set on the dynamometer,

the motor was cooled to ambient temperature, the

motor was energized and allowed to come to speed,

the load was applied, and the current was monitored

for 20 s. The loss of power on the motor was linear;

the current decayed 1 amp per second. Two amp is

roughly one ft/lb of torque on this motor. Thus, motor

heating caused the motor to lose 10 ft/lb of output in

20 s. Figure 47 shows these results. These results

partly explain the valve's failure to torque out on the

second cycle during the HDR tests. The motor heated

up during the first cycle and did not have the power

to trip the torque switch in the second cycle.

The dynamometer testing results provide answers to

several of the questions involved in the valve functional

anomaly at the HDR; however, they do not explain

the root cause of the valve stalling at near 50 amp at

41
Table 8. Results of motor operator testing at Limitorque Laboratory

Torque

Test Switch

No. Setting

1

2

3

4

5

6

6.1

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

32

33

34

35

36

2.00

2.00

2.50

2.50

2.90

2.90

2.90

2.90

3.10

3.10

3.10

3.50

3.50

3.50

3.50

3.75

3.75

3.75

4.00

4.00

4.00

4.20

4.50

4.50

4.50

4.50

4.75

4.75

3.50

3.50

3.50

3.50

3.50

3.50

3.50

3.50

Set

Voltage

(Vdc)

110

125

125

110

110

110

125

125

125

110

100

100

100

110

125

125

110

100

100

110

125

100

100

100

110

125

125

110

90

80

80

80

90

100

110

125

Minimum

Voltagea

(Vdc)

108

110

121

107

105

105

120

120

119

104

95

94

94

104

119

118

103

94

93

103

118

93

92

91

102

116

112

99

85

75

73

79

89

99

109

124

Plotter

Peak

Current

(amp)

9.0

15.0

15.0

21.0

21.0

25.0

25.7

26.0

29.5

34.0

35.0

34.0

41.0

39.0

40.0

38.0

39.0

42.0

42.0

46.0

46.0

46.0

50.0

58.0

56.0

54.0

51.0

75.0

66.0

39.0

40.0

41.0

Peak

Torque

(ft-lb)

99

88

125

132

154

185

169

176

220

229

231

242

275

242

264

277

264

245

286

286

264

308

352

363

330

308

484

407

231

255

220

Peak

Thrust

(lb)

4480

3982

5656

5973

6969

8371

7647

7964

9955

10362

10453

10951

12444

10951

11946

12534

11946

11086

12942

12942

11946

13937

15928

16426

14933

13937

21901

18417

10453

11539

9955

Comments

No load/baseline

Stall

Stall

No-load

No-load

No-load

No-load

No-load

5.5

5.3

6.0

6.0

6.0

a. Derived from visual readings.

42
RPM versus load

0 10 20 30 40

Load (ft-lb)

Current versus load

50 60 10 20 30 40 50 6o

Load (ft-lb)

15U

140

130 - 120 0. 110 E 100

s o C 70 G) 60

* 50 M 4 0

C 30

20

10

0 Actual performance

- Predicted performance

150

140

130

-a120 E 'lo 0

,100

_90

- 80

C 70

zD 60

50

o 4030

20

10

D r

0 Actuat performanc*

- Prodcted performanc*

Time -01

TWn

20 :.C*

I I . I . . . . . I . 0*.....

0 10 20 30

Load (fl-Ib)

40 so 60

.c*efl,

Figure 46. Results of motor dynamometer testing at

Peerless.

the HDR. Voltages during the dynamometer testing at

Limitorque were dropped to 80 Vdc, 20 volts below

minimums, in an attempt to reproduce the HDR motor

operator performance, yet the results could not be

duplicated.

3.6.3.6 Analysis of the HDR Power Circuit. Concurrent with Limitorques assistance to the INEL with the

HDR investigation, a utility called upon Limitorque

to assist with similar dc motor-actuated valve problems.

The utility was a two unit station, and all of the dc

powered valve problems were associated with one unit.

Several control circuit problems were found during the

investigation, and the root cause of the dc motor failures had been attributed to those problems. Interestingly, the power cables in the unit having problems were

smaller than those in the other unit. However, this difference was not highlighted in the investigation.

Shortly afterwards, Limitorque published a maintenance letter that contained an electrical circuit

calculation basis for dc motor operated valves. This

calculation was developed from Limitorque's investigations of dc motor problems at HDR and at the utility

mentioned above. In most dc motor operated valve control circuits, the armature coil and the series fields are

interconnected through the motor controller, and four

power cables must be considered in the calculation,

0 10 20 30 40 so 60

Load (ft-Ib) MA

Figure 47. Effects of motor heating, as demonstrated during motor testing at the Peerless laboratory.

not two as one might assume. Limitorque recommended using this calculation to determine voltage drop

instead of trying to measure the voltage drop in the

circuit. In attempts to measure the voltage drop, it is

very difficult to load the circuit and sum the various

voltage drops.

From this new methodology we developed an analytical model for the HDR valve power circuit to determine the influence of external circuit resistance on the

HDR valve anomaly. The HDR in situ tests and the

Limitorque tests were chosen for comparison, as the

motor operator was operated a comparable number of

times over the same period of time at both locations

and the size of the large external circuit cabling at

Limitorque should eliminate the influence of any external circuit resistance. Two different calculations of

the HDR power conductor resistance were made: one

was based on the size and approximate length of the

cables, and the other on measurements of the current

through the circuit and the voltage drop across the portion of the circuit that was measured. The calculations

were comparable. Four times the calculated resistance

for a single cable was inserted in the analytic model

to account for the armature and the field being connected in series through the motor controller. The

measured parameters from the HDR in situ testing

and the Limitorque dynamometer testing were then

43
analyzed and actual motor resistances calculated.

Very good comparisons were found. The results

demonstrate that the differences between the motor

operator performance at HDR and the performance

at Limitorque were caused by external circuit

resistances.

These results point out the significance of the external circuit resistance and motor heatup in reducing the

safety margins of motor operator torque output. High

external circuit resistance and motor heating are not

usually detectable in normal plant in situ testing, where

valves are tested with no load or with a static pressure

load alone. This was quite apparent from HDR in situ

testing, where the motor operator operated successfully

with no pressure, static pressure alone, and with static

pressure and very low differential pressure. When the

differential pressure from the flow load was increased,

the valve either failed to close all the way or the

operator motor stalled, depending on the torque switch

setting.

To understand this in situ problem, one must understand dc motors. These motors generate a back electromotive force (EMF) when turning. This back EMF

acts like a bucking voltage in the circuit. Stated in an

over-simplified way, this back EMF limits the current

in the circuit much the way a resistance would. The

back EMF is proportional to the motor speed and current. These high-torque compound-wound motors have

a weak shunt field and act very much like a series

wound motor in application. As the load is increased

the motor slows down, reducing the back EMF. This

allows more current to flow, thus producing higher

torque. This behavior continues down to motor stall,

where the dc resistance of the motor is the only internal resistance to current flow. These motor resistances

at or near locked rotor are in the 1.0 to 1.5 ohm range

for a 40 to 60 ft-lb output torque motor operating on

125 Vdc. Because the field and armature cabling are

connected in series through the motor controller, four

long cable runs, not two, contribute to the resistance

of the external circuit. External circuit resistance of

just 0.5 to 1.0 ohm can reduce the motor output torque

by 1/3 to 1/2.

During normal valve testing or operation, the resulting motor loadings are in the 20 to 30% running torque

range. The back EMF or effective motor resistance

would be approximately 5 ohms, and a 0.5 to 1.0 ohm

external resistance would not significantly degrade

motor performance. This conclusion was supported by

the results of the HDR static pressure testing. However, during a transient or a line break where isolation is required, the high differential pressure across

the valve disc would require a higher motor output,

and the external circuit resistance in series with the

motor resistance could reduce the output torque of the

motor significantly, as it did at the HDR during tests

with flow loads.

At the end of our investigation of the valve's

anomalous performance at HDR, we had identified

three separate problems. The potential safety implications of these problems are significant.r aing 

can result in a valve that torques out early and, depending on the extent of the degradation, can leave the valve

partially open. Coil spring aging in the older SMA

motor operators may go undetected, as there are fewer

diagnostic test systems adaptable to these units. Motor

heating can reduce motor operator output if the valve

is cycled more than once without time for the windings

to cool. If a marginally powered valve is subjected to

high loads on closing, this reduced output can result 67

in motor stall, probably with the valve partially open.

External circuit resistance also can cause the moto2r tn

stall before the valve fiullyx1Cn Motor stall can cause

the thermal overload switches to open and render the

motor operator temporarily unavailable for use. If the

thermal overload switches have been bypassed or set

too high, or if they malfunction, the motor will burn

QWAn. High external circuit resistance in both the SMA

and the newer SMB operators with dc motors can go

undetected in 'nrmal m`situ valve testing. The problem

is detectable only at higher loadings when the motor

is slowed down and momentum can not carry the unit

through torque out.

A complete discussion of the anomalous performance

of the valve is given in Appendix A (Volume 2). Appendix A also gives a description of the valve and its

refurbishment and subsequent installation in the HDR.

3.6.4 Valve Dynamic Analysis. HDR SHAG test

results indicated an unexpectedly large high-frequency

response of the gate valve installed in the VKL. In addition, accelerations (transverse to the valve stem) were

significantly amplified from the valve body to the valve

operator. These results were not anticipated by bench

testing.

Seismic qualification of line-mounted equipment is

currently based on bench tests and analytical calculations. As part of its refurbishment, INEL dynamically

tested the valve to Annex "E" Exploratory Vibration

Test of ANSI B16.41, and determined the valve's

natural frequencies. The lowest natural frequencies

found were 28 Hz and 48 Hz, respectively, in the directions perpendicular and parallel to the valve flow axis.

The valve perpendicular axis is X; the direction parallel

to the flow axis is Z. Valve qualification standards

define flexible and rigid valve assemblies by their

fundamental frequency, and the qualification requirements differ accordingly. Valve assemblies having

..frencies below 33 Hz are considered flexible and

require rigorous testing as defined in the awruator

44
qualification standard.-Valve assemblies having fundamental frequencies above 33 Hz are considered

rigid, and seismic qualification can be as simple as a

yoke deflection test. The standards also allow both rigid

and flexible assemibla-w-bequalified by analyses

without testing. Typically in industry, the decision as

to whether a valve is flexible or rigid is made by comparing the fundamental frequency of the valve with the

response spectra for the valve installation. If the

fundamental frequency of the valve falls within the

amplified portion of the spectra, it is considered flexible, and if it is above, it is considered rigid. The lowest

frequency of this valve was 28 Hz, which was well

above the amplified portion of the HDR installation.

It was considered a rigid valve for the HDR and would

have been also considered rigid for most U.S. plant

applications.

The in situ environment at the HDR presented an

excellent opportunity to compare valve dynamic performance determined by bench testing with actual

in situ dynamic behavior. During posttest evaluation

of the valve response data, examination of the valve

acceleration histories revealed considerable amplification of response at the valve motor operator as compared to corresponding response of the valve body.

Triaxial accelerometers were located on the body, at

the center of gravity, and on the motor operator. Further evaluation of the responses in the frequency

domain revealed amplification at frequencies above and

below bench-tested lower-mode frequencies. The

higher frequencies are considered important, as most

seismic qualification addresses only frequencies less

than 33 Hz. The maximum excitation frequency input

to the HDR building was 8 Hz, and high-frequency

(greater than 33 Hz) amplified response of the valve

actuator was not expected.

3.6.4.1 Investigation of High-frequency Amplification

Owing to the potential significance of this finding on

qualification requirements for valve-operator and

operator-mounted valve control components, the

phenomenon was investigated in detail. The objectives

of the investigation were (a) to quantify and compare

the measured response, (b) to determine if the

response was influenced by piping support configuration, and (c) to determine, if possible, if the highfrequency response was generated within the valve or

was an amplified response generated external to the

valve.

The U.S. stiff and Kfl( flexible support systems were

selected for study since they should envelope the piping

system response. The 8-Hz starting frequency was

selected so that the greatest input excitation frequency

bandwidth was available. These tests were designated

T40.30 (U.S. stiff) and T40.10 (KfK flexible).

As previously described, the data indicate that the

excitation of the piping system was predominately

caused by motion of the HDU vessel at the two nozzle

connections to the VKL. Therefore, the accelerometer

locations studied were those at the top of the HDU,

at the valve, and at available intermediate VKL accelerometer locations. In this discussion, these locations

are designated Top HDU, Standard T, Spherical T,

Valve Body, and Valve Operator, corresponding to

instrument locations 8, 16, 9, 40 and 42, respectively. These locations are shown in Figure 48. Since each

of these five locations was instrumented with triaxial

accelerometers, a total of fifteen transducer output

records were studied for each of the two tests.

Frequency domain analysis was used to study and

compare the behavior of the five locations. Standard

procedures were used to calculate auto-spectra [power

spectral densities, (PSDs)] of the acceleration records.

Appendix E (Volume 2) contains a complete discussion of the valve dynamic analysis.

A standard technique in frequency analysis is to

average the PSDs obtained from several sequential time

frames in order to minimize the effect of noise in the

measurements. However, for the measurements studied

herein, several of the resonant peaks in the PSDs

changed in frequency as a function of the time frame

studied because of the coastdown of the shaker. Thus,

averaging several sequential frames had the effect of

smearing these variable PSD peaks. In order to reduce

the smearing effect, analysts studied and compared the

data on a frame by frame basis.

Subsequent discussion of analysis and results deals

with the first 8 s of the transient. The data acquired

by KfK was low-pass filtered at 30 Hz during acquisition; thus, the potential high-frequency (33 to 50 Hz)

information present at the top of the HDU vessel and

at the spherical tee may have been removed from the

acceleration histories recorded for these locations. Data

acquired by INEL was low-pass filtered at 200 Hz, so

this is not a problem for the other measured points.

Figures 49 through 51 reproduce the first-frame

PSDs found in frequency analysis of the 30 acceleration histories (X, Y, and Z directions for each of the

five locations, and for each of the two tests). The

figures present the PSDs of the major excitation source

(the top of the HDU) on the left, then follow the load

path from left to right through the standard tee, the

spherical tee, the valve body, and the valve actuator

(located on the far right). Each figure represents either

the X, Y, or Z response direction, with the KfK flexible system shown at the top of the figure, and the U.S.

stiff system shown below.

Figure 49, the X axis PSD matrix, shows essentially the same HDU response for both systems. Comparison of the standard tee responses shows for the

45
Y

x

'-,,6 1 Instrument

94 Numbers

Flow//

Valve detail

Figure 48. Instrument locations for the dynamic load path from the HDU vessel to the 8-in. gate valve.

flexible system a greater response in the low-frequency

range, as expected, with the higher-frequency distributions slightly different, but not significantly so.

INEL/MPA monitored the standard tee instrumentation location. As previously discussed, these data were

not filtered at 30 Hz; high-frequency content is shown.

However, instrumentation located at the spherical tee

was monitored by KfK and, for the most part, the highfrequency content of the response appears to have been

filtered out.

For all instrument locations in the frequency range

less than 10 Hz, the U.S. stiff system frequency distributions follow the HDU response with a narrow band

response, whereas the flexible system response

distribution is more broadbanded. For valve body and

operator instrument locations, note again that response

data are unfiltered at 30 Hz; high-frequency content

is present. The valve responses also indicate a lower

frequency content for the flexible system than is seen

in the stiff system response.

Comparison of the valve operator responses with the

valve body responses shows considerable amplification and band broadening, especially for frequencies

above 10 Hz. We believe that the 8-Hz response peak

appearing in all of the plots represents near rigid body

motion of the entire VKL system and follows the

shaker input excitation. The remainder of the response

bands do not appear to be harmonic components of the

shaker excitation; we assume that they represent

dynamic response modes of the VKL system and HDU

vessel. Note that no significant amplification occurs

between the HDU and the valve body.

The most significant peak appearing in the operator

responses, other than the shaker-induced 8-Hz peak,

occurs near 20 Hz. We consider this amplification at

20 Hz to be the results of a resonance, since it appears

46
KFK IIePNbte systlem

Valve operator

10

C;7

0~

(0

a,5

Co

a)

C.,

0 10 t 40 0 10 20 30 40

Frec) Frequency (Hz)

US stitt system

10

- 10-'

Ct

-2

U)

DL 10-2 a

0

10-3

10- L

0 10 0 40 0 10 20 30

Freqz) Frequency (Hz)

7-8697

47
Valve body Valve operator

1I ItCI IIIJV - ll; VlKllll\Allt I

50 ilo 10 20 30

Frequency (Hz)

40 50 0 10 20 30

Frequency (Hz)

40 50

Valve body Valve operator

1'1I jA ,I iA (\AIA! I A

50 0 10 20 30 40 50 0

Frequency (Hz)

10 20 30 40 50

Frequency (Hz)

7-8898

e from the KfK flexible and U.S.
KFK flex

ive body Valve operator

N U

I

U,

CL

c 11

C.

o

a,

<I 0L) 1

ncy (Hz) Frequency (Hz)

US stiff so

a body

N

m 1.0-1

to)

C 10 CL0

C 0-

.2

C-)

0 1

1023

0 30 40 50 0 10 20 30 40 50

cy (Hz) Frequency (Hz)

HDR gl

7-8899

U.S.

49
in all of the PSD plots. However, since the resonance

is independent of piping configuration, it may be

caused by a local valve vibration mode. This mode was

not detected during the bench fundamental frequency

determination tests of the valve prior to installation in

the VKL. Also, the 20 Hz mode is strongly present

at the HDU top, which indicates the possibility of this

being a mode of the HDU, transmitted through the

VKL and amplified at the valve operator. An additional

peak seen in the two valve operator PSDs occurs near

30 Hz. This resonance may be caused by a local valve

vibration mode measured during the bench tests to

occur at 28 Hz, where the difference between in situ

installation and bench shaker mounting stiffness could

account for the difference in frequency. Significant

response amplification is seen for frequencies greater

than 40 Hz, especially for the stiff configuration. The

response peak located at 47 Hz may be owing to cross

coupling between the Z and X axes, where a local valve

resonance was found during bench tests to occur at

48 Hz (global Z axis).

Figure 50 presents global Y direction (vertical)

acceleration response PSDs in a manner similar to the

figure discussed above. Examination of the PSDs

shown in this figure illustrates the source of the differences between the flexible and stiff system strain,

displacement, and load responses. Comparison of the

HDU and standard tee results indicates that their responses are independent of the support configuration.

However, for the spherical tee and valve responses,

there is significantly greater low-frequency (less than

10 Hz) acceleration for the flexible configuration.

Since displacement, strain, and force are much more

influenced by low-frequency acceleration than by the

higher-frequency accelerations, differences in lowfrequency vertical acceleration dominate the observed

difference in load and strain between the two systems,

as discussed in Section 3.3. The difference in observed

response is probably primarily due to the presence of

the vertical snubber (H-6) located at the spherical tee,

which was not installed in the flexible configuration.

Again, some high-frequency response is observed at

the valve. However, there is little amplification of this

response from the valve body to the operator; the valve

vertical response appears to be primarily rigid body.

This is as expected, since the valve assembly is extremely stiff in this direction.

Figure 51 presents acceleration PSD comparisons

for response in the global Z direction. As in the X and

Y directions, response of the HDU is very similar for

both configurations. Significant high-frequency acceleration is observed for both configurations at the

standard tee. Spherical tee responses have similar frequency distributions with somewhat different magnitude distributions. For lower and higher frequency

ranges, and for both configurations, the valve body has

decreased response as compared to the standard tee.

This may be because of anti-resonances at the valve

body for frequencies within these ranges, or the

Z-direction response is attenuated by horizontal supports located at the spherical tee. The valve operator

responses, for both configurations, show significant

high-frequency content and amplification when compared with all other Z-direction responses. This

amplification is especially significant for frequencies

between 35 and 45 Hz. Recall that bench test results

indicate a local valve natural mode at 48 Hz, which

may influence the observed amplification at the higher

end of the frequency range.

Appendix E (Volume 2) reproduces all PSDs, including both the first and second 8-s data frames, and

presents a more quantitative comparison of acceleration response and band integrated PSDs. Portions of

the band-integrated data are graphically reproduced,

showing valve-body-to-actuator amplifications and

allowing frequency-distribution comparisons between

the two support configurations for each response point.

In summary, all results presented show significant

high-frequency (35- to 45-Hz) acceleration at the valve

operator, and significant amplification of this acceleration from the valve body to the operator for the

horizontal (X and Z directions) acceleration components. In the vertical direction (parallel to the valve

actuator shaft), valve high-frequency content was

significantly less, with little or no amplification between the valve body and operator. Even though the

driving point (HDU top) acceleration records have been

low-pass filtered at 30 Hz, there is evidence of some

higher-frequency accelerations. We believe that the

high-frequency acceleration experienced by the valve

originated at the primary driving point, the HDU top,

and was amplified by transmission through the VKL.

Analysis results show that most amplification occurred

between the valve body and valve operator. Bench frequency tests of the valve, prior to installation in the

VKL, indicate that the valve assembly did not contain

natural vibration modes in the frequency range of 30 to

45 Hz. Analysis also indicates that the high-frequency

acceleration content and amplification present at the

valve operator was experienced for both flexible and

stiff configurations. However, the frequency distributions did differ for these configurations.

It is well known that the stiffness of a piping system

changes its response frequency, and its response frequency changes the input to the line-mounted equipment within the system. The small variations in valve

response between the flexible and stiff systems in the

horizontal axes are insignificant. The primary difference appears in the piping system's low-frequency vertical response. The acceleration amplification across

50
the valve assembly contains a slightly different frequency distribution, but significant amplification is

present in both piping support system responses.

To further verify the significant high-frequency valve

operator acceleration response observed during the

HDR SHAG tests, we performed a limited examination of the results of a similar but related study, the

Containment Penetration System (CPS) dynamic test

[see Reference 13 (NUREG/CR-4734)]. That examination, reported in Appendix E (Volume 2), showed

that even though the CPS geometry and excitation

method were very different from those of the VKL at

HDR, the acceleration responses of the CPS gate and

butterfly valves were strikingly similar to the VKL gate

valve responses. We conclude that the observed

frequency-dependent behavior of the three valves is

primarily a function of the valves' dynamic characteristics rather than the piping system geometries or the

excitation methods.

The high frequency observed in the motor operator

response during HDR tests is not accounted for in

typical valve qualification. It is not expected that

response in these frequency ranges will affect the valve

structurally. However, they may affect valve operability by causing switches, relays, and other valve

control and indication devices to chatter. The nuclear

industry does not qualify these control devices to the

frequencies that may be seen in an actual event.

51
4. CONCLUSIONS

The HDR presented a unique opportunity to research

valve and piping system response in a reasonably

typical in situ environment. In combination, the in situ

loads input to the VKL system during the SHAG test

series were sufficient in magnitude to provide understanding of valve and piping system responses. Analyses of the measured input and response data yield both

confirmatory and conflicting evidence for support of

current equipment qualification practices and piping

system support technology. Following are INEL's

several conclusions from its participation in the HDR

SHAG Project.

4.1 Building and Piping

System Responses

Pipe support system design can increase system

reliability and reduce thermally induced stresses. A

strong movement currently exists in the technical community to revise seismic design standards for piping

in nuclear power plants. The philosophy behind present U.S. seismic design has been to raise the natural

frequency of the piping system above the natural frequency of the building, thus reducing resonant interaction. The disadvantage of this type of design is that

it may increase stresses caused by thermal expansion

and independent building or anchor motion. The stiff

piping support system typically uses snubbers, which

have a history of locking up even without dynamic

load. Locked up snubbers increase thermally induced

stress, which can have serious consequences (the incident at Trojan with the reactor coolant loop is a case

in point; see Reference 14).

A major portion of the HDR SHAG test series was

concerned with measuring the piping system responses

produced by various support configurations. A wide

range of system stiffnesses were investigated, including

a very flexible system, a moderately flexible system

typical of nonnuclear power piping design, and a stiff

system typical of U.S. nuclear design. Posttest analyses of very flexible and stiff system responses

indicated, as would be expected, that stiff system

dynamic response stresses were less than the corresponding flexible system stresses. However, the

relative differences were not as great as would be expected. The moderately flexible system, with 50%

fewer supports than the U.S. stiff design, responded

with a smaller total system stress than any of the other

systems tested. This may have been because the duration of the excitation, though conservatively representative of earthquake strong motion excitation duration,

was not long enough for the lower frequency modes

of the moderately flexible system to reach maximum

response.

Further analysis of experimental results is needed.

KfK and ANL have the research assignments for

indepth piping analyses. However, from the limited

analysis we performed to understand equipment response issues, the results suggests the advantages of

more flexible designs for nuclear piping systems.

4.2 Snubber Responses

Modem snubbers perform their function in a dynamic event; however, they may be susceptible to in-plant

aging. The four INC snubbers installed during the

preliminary tests at HDR failed to meet the manufacturer's specifications. Three of them failed to lock up,

and one locked up with the pipe deflected 0.5 in. Posttest discussions with the staff of USNRC and with

snubber vendors indicated that INC-designed snubbers

have been removed from U.S. nuclear power plants,

so these failures do not point out a safety problem.

The Pacific Scientific snubbers appear, with one

exception, to meet the manufacturer's specifications.

They also appear to have sufficient margin, as repeated

testing at ASME Code Level C allowable loads did not

degrade their performance. The one exception was

pointed out in the snubber section of this report, where

the snubber at H-I failed to resist dynamic motion for

3 or 4 s during Test T40.30. This anomaly will be investigated in follow-on testing. We do not expect this

to indicate a safety problem.

The snubbers used at HDR were not subjected to

environmental aging as they are in nuclear plants.

Aging problems were not experienced at HDR. We

conclude from the HDR testing that when the mechanical components of the snubber are operable they resist

motion at near load capacity.

4.3 Snubber Replacement

Devices Compared

The snubber replacement devices tested on the VKL

during the HDR experiments are all potentially more

reliable than snubbers. There are fewer moving parts;

hence, there is less chance for problems. However,

one must also consider the effect that these devices may

have on the response of the piping. The piping system

peak response will occur when a piping system is

excited at its natural or resonant frequencies. Piping

52
supports assist in establishing that natural frequency.

The more flexible Bechtel support will lower the

natural frequency of the piping system. The ANCO

devices appear to be stiffer than snubbers. The Cloud

device is the most flexible of all, since it does not

restrain the pipe until impact. A problem that could

result with the impacting type of support is that it

can generate high frequency response. Line-mounted

equipment typically is seismically qualified for 33 Hz

and less. The high frequency response may well have

an adverse effect on the control components for valves

and other line-mounted equipment. High frequency

response should be considered before use of the impact energy absorber.

These devices may increase the reliability of seismic

restraints without increasing thermal induced stress.

However, increased pipe reliability should not be

traded for decreases of reliability in line-mounted

equipment.

configurations, which envelope most of today's

operating systems.

The anomalous performance of the motor operator

was not related to the seismic loads imposed during

testing. Three factors contributed to the valve's

anomalous performance: torque spring aging, motor

heating, and undersized power cables. Test methods

could be devised that would determine the condition

of the torque spring and indicate whether the torque

switch setting needed to be changed and whether the

spring needed to be replaced. The failure of the motor

operator to torque out was caused

heating and mostly by undersized power cabling. Current in-plant testing with no loads or with static pressure

loads alone cannot detect these two problems.

Where these three problems exist undetected in the

field, valves subjected to design flow and pressure

loads might not completely close. If the thermal overload switches malfunction or if they have been bypassed in a motor that stalls, the motor could burn out.

M I

I!

4.4 Valve Response

Valves are inherently rugged and, typically, are

structurally not affected by seismic dynamic excitation.

The naturally aged motor-operated valve obtained from

the Shippingport Atomic Power Station was manufactured prior to equipment qualification requirements

applied to valves procured today. However, the valve

is still quite similar to valves procured today and is

representative of units in the older plants and reasonably representative of the valves in newer plants.

The motor operator manufactured by Limitorque

(Model SMA) was manufactured from mid-1950s to

mid-1960s and is representative of motor operators

installed in the older plants (plants going on line up

to the late 60s). The valve and operator were exposed

to a significant number of dynamic excitations and performed as designed, with the exception of failure of

the valve to close completely and to torque out on closing. HDR testing verifies that valve and piping systems

are structurally inherently tough. Based on the loadings

input at HDR and the measured system strains, considerably higher loadings could have been applied

before reaching near yield stresses of the system. This

is true for both the very flexible and the stiff support

4.5 Valve Dynamic Analysis

Valve qualification standards may not envelope

actual response frequencies in a dynamic event. Valve

seismic qualification tests verify design. Standards

allow generic and family group testing, which is as it

should be for these very rugged structures. The vulnerable components of typical valve assemblies, if any

exist, are the operator controls and switches. The HDR

and CPS dynamic testing results indicate that the

qualification methods and requirements may not adequately envelope the magnitude and range of frequencies that the valve operator can experience. It is

possible that high frequency responses at the operator

could cause switches and relays to chatter. This may

not be a problem, as the control devices may not be

effected by these inputs, but we cannot conclude this

from the subject testing. The information obtained from

the HDR and CPS valve response will be presented

to the ASME equipment Qualification Main and Valve

Subcommittees for their consideration. The highfrequency response of the motor operator will be

investigated further in the follow-on SHAM test series

at HDR.

53
5. REFERENCES

1. S. H. Bush, P. G. Heasler, and R. E. Dodge, Aging and Service Wear of Hydraulic and Mechanical Snubbers

Used on Safety-Related Piping and Components of Nuclear Power Plants, NUREG/CR-4279, PNL-5479,

Vol. 1, February 1986.

2. Mechanical Shock Arrestors, Standard Design Specification, DR-1319, Pacific Scientific Company, 1346

South State College Boulevard, Anaheim, California 92803, April 1975.

3. J. E. Glauser, Aerospace Technology Applied to Nuclear Power Plant Problems, Pacific Scientific Company, 1346 South State College Boulevard, Anaheim, California 92803.

4. J. Glauser, "Application of Mechanical Snubbers for Seismic Restraint," Nuclear Engineering International,

May 1978.

5. American Society of Mechanical Engineers, Boiler and Pressure Vessel Code, Section III, Subsection NF,

Component Supports, 1986 Edition.

6. United States Nuclear Regulatory Commission, USNRC Standard Review Plan, Section 3.9.3, ASME Code

Class 1, 2, and 3 Components, Component Supports, and Core Support Structures, NUREG-0800, 1981.

7. United States Nuclear Regulatory Commission, Qualification and Acceptance Tests for Snubbers Used in

Systems Important to Safety, Draft Regulatory Guide SC 708-4, Rev. 1, 1981.

8. American Society of Mechanical Engineers, Examination and Performance Testing of Nuclear Power Plant

Dynamic Restraints (Snubbers), ANSI ASME OM4, 1982.

9. American Society of Mechanical Engineers, Boiler and Pressure Vessel Code, Section XI, Subsection IWF,

Requirements for Class 1, 2, 3 and MC Component Supports of Light-Water Cooled Power Plants, 1979

and 1986 Editions.

10. Celesco Transducer Products, Inc., Celesco Transducer Catalog, 7800 Deering Avenue, Canoga Park, California 91304-5005.

11. American Society of Mechanical Engineers, Functional Qualification for Power Operated Active Valve

Assemblies for Nuclear Power Plants, ANSI B16.41.

12. Idaho National Engineering Laboratory, Valve Research HDR/VKL Phase 11 SHAG Testing Requirements,

EGG-REQ-7148, Rev. 2, May 1986.

13. Idaho National Engineering Laboratory, Seismic Testing of Typical Containment Piping Penetration Systems,

NUREG/CR-4734, EGG-2470, December 1986.

14. Memorandum from C. E. Rossi to T. L. Chan Dated June 11, 1986, Subject Safety Evaluation of Inoperable

Steam Generator Snubbers on the Trojan Nuclear Plant Reactor Coolant Loop (TAC #61405).

54
NRC FCRv 335 U.S. NUCLEAR REGULATORY COMMISSION 1. REPORT NUMBER (2 691 (Ausign-d by NRC. Add Vol.. Ss.. Re... NRM1 102B And Addend.1~Non,be~,sIf my.I

3201,3lG20 BIBLIOGRAPHIC DATA SHEET NUREG/CR-4977

(See instrucrmons on the reverse) EGG-2 505

2. TITLE AND SUBTITLE Vol. 1

SHAG Test Series

Seismic Research on an Aged United States Gate Valve and on a 3. DATE REPORTPUBLISHED

Piping System in the Decommissioned Heissdampfreaktor (HDR): MONTH YEAR

Summary AuQust 1989 4. FIN OR GRANT NUMBER

___2__A6322

S. AUTHOR(S) 6. TYPE OF REPORT

R. Steele, Jr., J.G. Arendts Technical

7. PERIOD COVERED {lnclus,.e Oares)

8, P E RFO RMI NG O RGAN IZAT ION -N AME AN D ADD RESS [lf NRC oovidrDivision.Office orRegion. U.S.N.clea.Regulatory Commiuson.~ mn ailing addrejss if conrwaro,. Provide na ne &nd miling addmss.J

Idaho National Engineering Laboratory

EG&G Idaho, Inc.

Idaho Falls, ID 83415

9. SPONSORING OR GAN IZATI ON - NAME AND ADDR ESS fit NRC. woer Samne as above if contracror. proide NRC Oivision. Office or Region, U.S. Nclear Reglarory Connision.

and maifing address.)

Division of Engineering

Office of Nuclear Regulatory Research

U.S. Nuclear Regulatory Commission

Washington, D.C. 20555

10. SUPPLEMENTARY NOTES

1'

The Idaho National Engineering Laboratory (INEL) participated in an internationally

sponsored seismic research program conducted at a decommissioned experimental reactor

facility, the Heissdampfreaktor (HDR), located in the Federal Republic of Germany (FRG).

The research program included the study of the effects of excitation, produced during a

simulated seismic event, on (a) the operability and integrity of a naturally aged 8-in. motoroperated gate valve installed in the Versuchskreislauf (VKL), an existing piping system

in the HDR, (b) the dynamic response of the VKL and the operability of snubbers, and

(c) the dynamic responses of various piping support systems installed on the VKL. The

INEL work, sponsored by the U.S. Nuclear Regulatory Commission (USNRC), contributes

to earthquake investigations being conducted by the Kemforschungszentrum Karlsruhe

(KfK) and is part of the general HDR Safety Program performed in behalf of the FRG,

Federal Ministry for Research and Technology. This report presents the results of the

KfK-designated SHAG (Shakergebaude) test series; these are the first in situ experiments

involving an actual nuclear power plant and a full scale piping system under simulated

seismic loading. Volume I presents a summary of the tests and results, and Volume 11

contains appendices that present details and specifics of the tests and results of

Volume I.

12. KEY WORDSIDESCR1PTOR S (Lit -.ords orphrases toat ,if assist resleanreern in locating the repors.I 13. AVAILABI LITY STATEMENT

unl imited

SHAG test series 14. SECURITY CLASSIFICATION

6 f~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Page) seismic research program uncassfie

aged gate valve unclassified

Piping system unclsaRssoif

Heissdampfreaktor (HDR) unclassified

simulated seismic loading 15 NUMBER OF PAGES

16. PRICE

NRC FORM1. 335 12-89)

*U.S.COVERNlPCNT PRINTINC OFFICE:1989-241-590%00199
1 1

UNITED STATES

NUCLEAR REGULATORY COMMISSION

WASHINGTON, D.C. 20555

SPECIAL FOURTH-CLASS RATE

POSTAGE N FEES PAID

USNFRC

PERMIT No. G-67

OFFICIAL BUSINESS

PENALTY FOR PRIVATE USE, $300

z

0

C)

CrA

-3

W

!