NUREG/CR-3521

SAND83- 1715

AN

Printed August 1984

Hyd rogen-Burn Survival Experiments

at Fully Instrumented Test Site (FITS)

Elizabeth H. Richards, John J. Aragon

Prepared by

Sandia National Laboratories

Albuquerque, New Mexico 87185 and Livermore, California 94550

for the United States Department of Energy

under Contract DE-AC04-76DP00789

SF2900Q(8-81)
NOTICE

This report was prepared as an account of work sponsored by an

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Available from

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U.S. Nuclear Regulatory Commission

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and

National Technical Information Service

Springfield, Virginia 22161
NUREG/CR-3521

SAND83-1715

AN

HYDROGEN-BURN SURVIVAL EXPERIMENTS

AT FULLY INSTRUMENTED TEST SITE (FITS)

Elizabeth H. Richards

John J. Aragon

Sandia National Laboratories

Albuquerque. New Mexico 87185

Operated by

Sandia Corporation

for the U. S. Department of Energy

Prepared for

Severe Accident Assessment Branch

Division of Accident Evaluation

Office of Nuclear Regulatory Research

and

Chemical Engineering Branch

Division of Engineering

Office of Nuclear Reactor Regulation

Washington. DC 20555

Under Interagency Agreement DOE 40-550-75

NRC FIN Nos. A-1270 and A-1306

ABSTRACT

A series of hydrogen-burn experiments conducted for the

Hydrogen-Burn Survival Program is described. The experiments,

executed at Sandia National Laboratories' Fully Instrumented

Test Site (FITS) facility in Albuquerque, provided data concerning the hydrogen-burn thermal environment as it relates

to equipment survivability in nuclear power plants.

The test plan, instrumentation, and results are presented,

along with a brief discussion of test volume (scale) considerations. Conclusions drawn from the results concern the

repeatability of the tests, the suitability of thermocouples

for measuring gas temperatures, and the effects of initial

hydrogen concentrations and fans on the responses of calorimeters and components. The effect of initial steam concentration on temperature response cannot be determined because

of preignition pressure considerations.

iii/iv

CONTENTS

Page

ABSTRACT iii

LIST OF ILLUSTRATIONS vii

LIST OF TABLES ix

ACKNOWLEDGMENTS x

EXECUTIVE SUMMARY 1

1. INTRODUCTION 2

2. TEST DESCRIPTION 4

2.1 Facility 4

2.2 Scale 5

2.3 HBS Instrumentation 5

2.3.1 Thermocouple Probes 7

2.3.2 Calorimeters 7

2.3.3 Heat-Flux Gages 12

2.3.4 Solenoid Valve 12

2.3.5 Additional Instrumentation 12

2.3.6 Instrumentation Location 13

2.4 Test Plan and Procedures 13

2.4.1 Test Plan 13

2.4.2 Data Acquisition 14

3. DATA ANALYSIS METHODS 16

3.1 Conversions and Adjustments 16

3.2 Treatment of Outliers 16

3.3 Smoothing of Data 16

4. RESULTS AND CONCLUSIONS 20

4.1 Gas-Temperature Measurements 20

4.1.1 Thermocouple Comparison 20

4.1.2 Peak Gas Temperatures and Initial

Pressure Correction 21

4.1.3 Effects of Hydrogen Concentrations 22

4.1.4 Repeatability 23

4.1.5 Effects of Fans 24

4.2 Flat-Plate Calorimeters 24

4.2.1 Results 24

v
CONTENTS

(continued)

Page

4.2.2 Effects of Hydrogen Concentrations and

Fans 25

4.2.3 Repeatability 27

4.3 Cube Calorimeters 29

4.4 Flux Gages 31

4.5 Solenoid Valve 31

4.6 Other 32

4.6.1 Mixing Fans 32

4.6.2 Cable Samples and Terminal Blocks 33

5. SUMMARY OF FINDINGS AND CONCLUSIONS 36

REFERENCES 37

APPENDIX A 38

vi
LIST OF ILLUSTRATIONS

Figure Page

1 Test Vessel at FITS 4

2 Relative Volume Comparison 6

3 Schematic Drawing of Thermocouple Probe 8

4 Photograph of Thermocouple Probe 8

5 Assembly Drawing of Flat-Plate Calorimeter 9

6 Flat-Plate Calorimeter Installed in FITS Test

Vessel 10

7 Location of Thermocouples on Solid and Hollow

Cube Calorimeters 11

8 Cube Calorimeters Mounted in FITS Test Vessel 11

9 Solenoid Valve Mounted in FITS Test Vessel 13

10 Location of Major Instrumentation in FITS Test

Vessel 14

11 Comparison of Unsmoothed Data and Data after

Smoothing with Butterworth Filter 17

12 Comparison of Smoothed and Unsmoothed Data for

a Gas-Temperature Peak 19

13 Thermocouple Response Comparison 20

14 Effect of Hydrogen Concentration on Peak

Temperature Rise 23

15 Typical Temperature Response for Flat-Plate

Calorimeter 25

16 Effect of Hydrogen Concentration on Peak FlatPlate Calorimeter Temperature Rise 28

17 Typical Temperature Responses of Hollow and

Solid Cube Calorimeters 29

18 Cube Calorimeters: Effect of Hydrogen Concentration on Peak Temperature Rise 30

19 Typical Temperature Response of Solenoid Valve 32

vii
LIST OF ILLUSTRATIONS

(continued)

Figure Page

20

21

Surface Temperature Response of Mixing Fan

Cable Samples

34

35

viii
LIST OF TABLES

Table Page

1 Test Matrix for FITS Series 1 15

2 Peak Gas-Temperature Rises ( 0 C) 22

3 Effect of Fans on Peak Gas-Temperature Rises 24

4 Flat-Plate Calorimeters: Peak Temperature

Rises (OC) 26

5 Flat-Plate Calorimeters:. Peak Temperature

Rises (°C) (Energy Factor Applied) 27

6 Flat-Plate Calorimeters: Effect of Fans on

Peak Temperature Rises 28

7 Cube Calorimeters: Effect. of Fans on Peak Temperature Rises 30

8 Temperature of Solenoid Valve 90 Seconds after

Burn Initiation 33

ix
ACKNOWLEDGMENTS

The Hydrogen-Burn Survival Program is a team effort involving

several SNLA organizations. The authors gratefully acknowledge the contributions to this effort by Bill McCulloch, Lou

Cropp, Ben Bader, Art Ratzel, Steve Kempka. Bob Padilla,

Vince Dandini, and the staff at the FITS facility. We also

thank Frank Wyant and Charles Craft for their help with

computer-related tasks. and Gene Aronson for help with data

reduction.

x
EXECUTIVE SUMMARY

As part of the Hydrogen-Burn Survival (HBS) Program, a series

of hydrogen-burn experiments was conducted at the Fully

Instrumented Test Site (FITS). These tests were designed to

provide thermal environmental data for the combustion of

hydrogen in mixtures of air and steam, to provide data concerning the thermal response of components, and to verify

computational models for medium-scale volumes.

The volume of the test vessel at FITS, 5.6 M 3 , is orders

of magnitude smaller than some of the volumes in reactor containments. Because of the widely varying surface area-tovolume ratios (and therefore different heat-transfer mechanisms), component temperature responses to burns in the FITS

tank are not necessarily representative of those in a containment. For example, although a Class IE-qualified solenoid valve survived all burns in the test series, a direct

conclusion regarding its hydrogen-burn survivability in a

reactor containment cannot be drawn because of the volume

scaling consideration. However, the large quantity of data

recorded for this medium-scale volume contributes to our

overall understanding of both the hydrogen-burn environment

and equipment response to that environment. It also provides

medium-scale verification of computational models..

Gas and component temperature data from 21 combustion tests

(burns) were recorded, reduced, and analyzed. Some findings,

such as (1) increasing hydrogen concentrations increased peak

temperatures and (2) thin-walled components responded faster

and reached higher temperatures than thick-walled components,

were expected. Some unexpected findings (e.g., smaller

thermocouples did not necessarily respond better than larger

ones) were also encountered. Fans appeared to promote more

complete combustion. The effect of steam concentration on

peak temperatures cannot be determined until the problem of

different preignition pressures is resolved.

1
1. INTRODUCTION

A concern evolving from the accident at Three Mile Island is

that considerably more hydrogen might be produced in a nuclear

reactor accident than had been previously considered for

design basis accidents. To prevent a severe hydrogen-oxygen

reaction from threatening containment integrity, several

methods of hydrogen control have been suggested. One such

method calls for the intentional ignition of hydrogen before

dangerously high concentrations accumulate. The pressures

resulting from these low-concentration hydrogen burns may not

threaten the containment building integrity; however, the

survivability of safety-related equipment exposed to the

burning-hydrogen environment is uncertain.

The primary near-term goal of the Hydrogen-Burn Survival (HBS)

Program at Sandia National Laboratories, Albuquerque (SNLA)

is to develop an analytical method for the Nuclear Regulatory

Commission (NRC) to use in estimating the survivability of

safety-related equipment during a hydrogen burn.[l] This

method will be in the form of an algorithm that will be

implemented on a desktop computer, and it will be supported

by both experimental and analytical work relating to hydrogen

burns. In the longer term, the HBS program is concerned with

developing an understanding of the hydrogen-burn environment

as it relates to component temperature response. The program

seeks to develop a technological basis for determining whether

consideration of the hydrogen-burn environment must be

included in the procedures used for qualifying equipment for

use in nuclear facilities and, if qualification is necessary,

for specifying qualification test procedures.

Several series of experiments have been conducted as part of

the HBS program. These include medium-scale hydrogen deflagration tests in pressure vessels and hydrogen-burn simulation

tests at the Sandia Central Receiver Test Facility (CRTF).

Program plans also include participation in the larger-scale

hydrogen-burn experiments conducted by the Electric Power

Research Institute (EPRI) at the Nevada Test Site (NTS).

Described herein is a series of medium-scale (5.6 m 3 )

hydrogen-burn tests at the SNLA Fully Instrumented Test Site

(FITS). This test series is referred to as FITS Series 1.

The purpose of FITS Series 1 was twofold. First, the

hydrogen-burn thermal environment needed to be characterized

so that it could be simulated in further tests at the CRTF.

Second, the tests provided medium-scale verification of the

computational models being developed as part of the analytical

portion of the HBS program. FITS Series 1. tests treated

single burns only; multiple-burn phenomenology is to be examined in later tests.

2
This report documents the HBS instrumentation and procedures

(test plan) for the FITS Series 1 tests. The analytical

methods used on the HBS data are presented, along with some

results and general conclusions.

3
2. TEST DESCRIPTION

2.1 Facility

The test vessel at the FITS facility is a 5.6 M3 . aboveground, steel tank constructed to ASME boiler codes

(Figure 1). The exterior of the tank is insulated with a

two-inch thickness of fiberglass. The tank has 25 flanged

ports, which can be used as instrumentation feedthroughs or

as viewing apertures. The FITS tank contains an array of 32

12-mil thermocouples used as flame-front detectors and (typically) 5 pressure transducers. A closed-circuit television

camera provides for visual observation of the burns and for

monitoring the occurrence of condensation.

Figure 1. Test Vessel at FITS

4
Before each test, the tank walls and instrumentation are preheated to the desired temperature by injecting superheated

steam into the tank and circulating steam through a copper

coil around the outside wall of the tank for several hours.

This is done to maintain wall and equipment temperatures

above the saturation point, thus preventing condensation from

forming on them. The tank is then purged twice with atmospheric air. each time pulling the tank pressure down to

about 10 kPa (1.5 psia). Atmospheric air is then vented into

the tank, and the hydrogen and steam are added to the air,

using partial pressures to obtain the desired concentrations.

Because of this filling method, each test has a different initial total pressure.

2.2 Scale

With a facility such as FITS it is important to consider the

relative volume of the facility as compared to the volumes in

an actual reactor (Figure 2). FITS is considered to be a

medium-scale test facility. Figure 2a shows the relative

volumes of several test facilities used in studying hydrogen

burns. The large cube represents the volume of the NTS test

vessel. The medium cube represents the FITS volume, and the

small cube represents the volume of a laboratory-size test

(such as that used in the Whiteshell tests).[2 3] A containment volume would be represented by a cube with sides of

length two to four times the length of the NTS cube sides, as

shown in Figure 2b.

It can be seen that widely varying volumes are used in the

testing conducted as part of the hydrogen-burn/equipmentsurvivability effort. This is important because:

* The dominant heat-transfer mechanisms appear to be

very dependent on volume

" Buoyancy effects may be much more important in a

large volume than in small volumes

" The volume-to-surface ratios are much larger in

large volumes. This affects the heat flux to the

components

2.3 HBS Instrumentation

In addition to the existing FITS facility instrumentation,

the HBS tests required 32 data-acquisition channels. These

provided for 2 thermocouple probes (each containing 6 spatially arranged thermocouples for gas-temperature measurements), 12 calorimeter temperature measurements, and 3 heatflux measurements. The remaining five channels were instrumented to measure the temperature responses of a solenoid

valve and two mixing fans inside the tank.

5
2b. I

E CONTAINMENT

VOL: 17000-85000 CU. METERS

SNTS "-II

,,sIVOL: 2100 CU. METERS

EFITS

VOL: 5.6 CU. METERS

S I

Figure 2. Relative Volume Comparison

6
2.3.1 Thermocouple Probes

Two thermocouple probes were designed to measure gas temperature at six locations within the FITS tank. Utilizing the

flanged ports on the tank, one probe was mounted so that it

was I m (3 ft) from the top of the tank: the second probe was

mounted 3 m (10 ft) below the top of the tank. As shown in

Figure 3, each probe had three pairs of Type K thermocouples

affixed to it. The thermocouples were bent so that the junctions extended into the gas and were not in contact with or

shielded by the probe. Each thermocouple pair consisted of a

5-mil beaded thermocouple and a 0.5-mil butt-bonded foil

thermocouple. This combination was chosen so that we could

compare the responses and survivabilities of the two types.

Because of the fast temperature transients which occur, it

was desirable to use very small (fast response) thermocouples

to measure the gas temperatures. On the other hand, thermocouples that were too small may have failed (burned up) after

just one or two tests. An important feature of the probes

was that they were easily replaced through the instrumentation ports without necessitating removal of the tank lid.

Figure 4 is a photograph of one of the thermocouple probes.

2.3.2 Calorimeters

Two types of calorimeters were used in the tests. First.

flat-plate calorimeters were designed to make their heattransfer characteristics as basic as possible so that posttest

analysis would be 'simplified. Second, three-dimensional

calorimeters were constructed to be more representative of

actual reactor components.

The main component of the flat-plate calorimeters (Figure 5)

was a brass plate 0.5-mm (20-mil) thick by 15-cm (6-in)

square. The front surface was coated with a highly absorptive, high-temperature, flat black paint (Nextelt m :

= 0.99). The back surface of the calorimeter was insulated and sealed. Two of these calorimeters were mounted on

the inside wall of the tank, one 1.2 m (4 ft) from the top

and the other 2.3 m (7.5 ft) from the top, with the back

insulated surface facing the wall (Figure 6).-

Three thermocouples were mounted on the back side of each

brass plate, one in the center and the other two 1.9 cm

(0.75 in) off-center vertically At the outset we had planned

to mount a thermocouple on the front side of the flat-plate

calorimeters, but heat-transfer calculations performed by Ben

Blackwell of Sandia National Laboratories showed that there

would be insignificant temperature differences between the

front and back sides. Because of low-temperature phase

changes inherent in brass, we attempted to use copper plates

instead of brass to simplify heat-transfer calculations.

However, we were unsuccessful at welding thermocouples to the

7
3/4"

<-- S.S. TUBING -- "

SWAGE-LOCK

MOUNTING NUT

---- 3/4" x 1/8" S.S. SHEET STOCK --

= THERMOCOUPLES- 6 TOTAL

0.5 MIL ON ONE SIDE

0.5 MIL ON OPPOSITE SIDE

3 i#---

F-- --- 3.---------------- -- - 42" -P-r

.-<-------------------------------------

Figure 3. Schematic Drawing of Thermocouple Probe

Figure 4. Photograph of Thermocouple Probe

8
A: -

A-A

-I

oI~

-BRASS PLATE 0.020" EPOXY ANNULET STANDOFF

1/4" PHENOLIC PLATE

3-1/2" THRU HOLE

1/8" FELT INSULATION

2 LAYERS IN HOLE

2 LAYERS ACROSS REAR

>• THERMOCOUPLES,

INTRINSIC 3 EA.

METAL ALUMINUM

TAPE

A r

BRASS PLATE

Figure 5.. Assembly Drawing of F1 A-t P aý' ;ýe P. 'alor.i.meter
copper plates even when the copper was nickel plated. Therefore, the use of copper plates was abandoned for FITS Series

1.

Figure 6. Flat-Plate Calorimeter Installed in FITS Test

Vessel

Two three-dimensional calorimeters were constructed as 10-cm

(4-in) black anodized aluminum cubes. One of the cubes was

hollow, constructed from 1/8-in aluminum sheet stock. It

represented components that have a low mass and therefore low

heat capacity. The other cube was solid, representing massive

components with high heat capacities.

Each cube was instrumented with three thermocouples. Foil

thermocouples were bonded to the hollow cube at two locations

on the inside surface and at one location on the outside surface. The solid cube was instrumented with beaded thermocouples. They were mounted in 0.32-cm (0.125-in)-deep holes

in the same locations as the thermocouples in the hollow cube

(Figure 7). The cubes were mounted about 2 m (6.6 ft) from

the top of the tank and 0.6 m (2 ft) from the wall. Figure 8

shows the cubes as mounted in the FITS tank.

10
x

v

XI

J-I--

X

I

Figure 7. Location of Thermocouples on Solid and Hollow

Cube Calorimeters

Figure 8. Cube Calorimeters Mounted in FITS Test Vessel

11
2.3.3 Heat-Flux Gages

Previous HBS tests and analyses indicated that the measurement of transient heat fluxes during combustion would be

valuable. This data would validate analytical procedures and

specify the transient radiant heat-flux criterion for the

simulation tests conducted at the CRTF. To begin development

of a reliable heat-flux measurement technique, some candidate

heat-flux gages were utilized in FITS Series 1. One of the

gages tested was designed to measure only radiative heat flux

(Thermogage Model 8000-12C). To minimize convective and conductive heat transfer from the gas to the sensing element,

the gage had an ellipsoidal cavity in front of the sensor and

required a continuous air purge to keep the cavity surface

clean and dry. The second and third gages were Gardon-type

circular-foil heat-flux gages.[4 5] They had slightly different configurations and calibrations, but both measured net

absorbed heat flux. Although we anticipated some problems

with these gages because none were designed for use in

facilities such as FITS. we felt they would provide valuable

experience for future efforts in measuring heat flux.

Two of the heat-flux gages were mounted on a bracket near the

tank wall 1 m (3 ft) from the top and were accessible only by

removing the top of 'the tank. The third gage was inserted

through an instrumentation port about 2 m (6.6 ft) from the

top. The gages all faced the centerline of the tank.

2.3.4 Solenoid Valve

To observe the behavior of a "real" component and to gain

some experience in instrumenting such components, we mounted

a Class IE-qualified solenoid valve about 1 m (3 ft) below

the top of the tank. The operation of the valve was checked

before and-after the test series. The alternating current in

the coil of the valve was monitored between burns. We mounted

a thermocouple inside the cover plate of the valve's electrical enclosure and monitored that temperature during the burns.

Figure 9 shows the solenoid valve as mounted in the FITS tank.

2.3.5 Additional Instrumentation

For additional information, we bonded two thermocouples to

each of the two pneumatic mixing fans inside the tank to monitor their temperatures during the burns. We also placed several cable specimens, both qualified and unqualified, in the

tank along with two types of terminal blocks. The cable samples and terminal blocks were included for visual inspection

purposes only; mechanical (e.g., tensile) or electrical tests

were not performed on the samples.

1.2
Figure 9. Solenoid Valve Mounted in FITS Test Vessel

2.3.6, Instrumentation Location

Figure 10 shows the locations of the major pieces of HBS

instrumentation. The cable and terminal block samples were

suspended near the center, about 1 m (3 ft) from the top.

The mixing fans are part of the permanent FITS equipment.

One is located 1 m (3 ft) from the top of the tank and the

other about 3 m (10 ft) from the top of the tank.

2.4 Test Plan and Procedures

Detailed information concerning the general operating procedures for the FITS facility can be obtained from Reference 6

and is not repeated here. However, the test plan and procedures pertaining to the HBS program tests will be discussed.

2.4.1 Test Plan

The HBS test plan called for a series of burns to be performed

that would provide information on low-hydrogen-concentration

burns in atmospheres with three different steam concentrations. (Concentrations of hydrogen and steam are expressed

as volume/percent [v/o] throughout this report.) Table 1

shows the matrix of burn tests that were actually performed.

13 1
These tests provided information- concerning the effects of

varying hydrogen and steam concentrations on the burn environment, the repeatability of the burns, and the effects of turbulence (fans on) during a burn, as well as the component

responses to the specific hydrogen burns. As noted in

Table 1, in. one test the hydrogen could not be ignited; in

seven other tests, no data were obtained because of problems

with the data-acquisition system.

INSTRUMENTATION LOCATIONS

__-= THERMOCOUPLE PROBES

+=HEAT FLUX GAGES

LI =FLAT PLATE CALORIMETERS

*E=CUBE CALORIMETERS

Figure 10. Location of Major Instrumentation in FITS Test

Vessel

2.4.2 Data Acquisition

The data-acquisition system at the FITS facility has the

capacity for storing about 2000 data points per channel.

Sampling 20 times per second, the system recorded about 100 s

(including 10 s of initial condition data) of data for each

burn. Data sampling was initiated by the increase in pressure associated with a burn. Sufficient time elapsed between

tests to output hard copy of some (but often not all) of the

data so that it could be scanned for indications of system

malfunctions. When malfunctions were found, corrective measures were taken before proceeding with the test sequence.

All of the raw test data from this test series were recorded

on floppy discs. To facilitate analysis, the data were

transferred to storage files on an SNLA VAX computer system.

14
Table 1

Test Matrix for FITS Series 1

Hydrogen

Concentration (v/o)

Steam Concentration (v/o)

0 20 40

6 0

0

0

X

X X

7

8

X

X 0

X

F

F

X

X

N

9 0

X

X

10 X 0

X

F

0

X

11

12

15

X

X X

X

X

0 = No data obtained (data-acquisition system

X = Data obtained; fans not on

F = Data obtained; fans on

N = No ignition

problems)

15
3. DATA ANALYSIS METHODS

The data was recorded as output voltages read from the various

pieces of instrumentation. Before they could be used, the

voltages had to be converted to the corresponding temperatures, heat fluxes, or pressures. In addition, the data were

treated to minimize the effects of noise in the electrical

circuits.

3.1 Conversions and Adjustments

A linear equation of the form y = mx + b + c was used to convert the voltages to temperatures, heat fluxes, or pressures.

In this equation, y = measured quantity, m = conversion factor, x = recorded voltage, b = reference value, and c = correction value. The measured quantity was either temperature,

heat flux, or pressure. The conversion factor for the temperature measurements was the appropriate value for Type K

thermocouples combined with the gain on the amplifiers, while

the conversion factor for the heat-flux and pressure gages

was the slope of their calibration curves combined with the

amplifier gains. The output voltage from each sensor was

recorded by the data-acquisition system. For thermocouples,

the reference value was the reference temperature (as recorded

for the reference junction oven); for heat-flux gages, the

reference value was zero; and for the pressure gages, the

reference value was calculated from the preburn pressure for

each burn. It was necessary to use a correction value on the

data from some burns in which a dc offset was discovered in

the amplifiers. Most of the hydrogen-burn analysis concerns

temperature rises or differences rather than actual temperatures; for these cases, b and c have no effect on the interpretation of the data.

3.2 Treatment of Outliers

An outlier is a spurious data point, often caused by electrical noise in the data-acquisition system. Several outliers

were discovered during a visual inspection of the data plots.

All gross outliers were removed using a computer program

explained in Appendix A, and more information concerning outliers can be obtained from Reference 7.

3.3 Smoothing of Data

As in most experimentally obtained data, some noise was present. Occasionally the noise was severe enough to warrant

rejecting the data from certain channels. Usually, though,

the noise was not very noticeable unless the scale of the

data plot was greatly magnified. Figure 11 shows an example

of this.

16
204 204

0

LU

I177

149

121

93

-10 0 10 20 30 40 50 60 70 80 90

TIME (seconds)

L)177/L

149

j 121

9 3 1 1 1 1 1 1 1 1

-10 0 10 20 30 40 50 60 70 80 90

TIME (seconds)

I-.'

-J

0-

LU

0.

LU

Im

193

192

191

190

189

A. ORIGINAL UNSMOOTHED DATA

B. ,.jSMOOTHED DATA

C. BLOW UP, COMPARING A & B

9 10 11 12 13 14 15

TIME (seconds)

Figure 11. Comparison of Unsmoothed Data and Data after Smoothing with Butterworth

Filter
Figure 11a shows the original temperature trace of a flatplate calorimeter exposed to a 10 v/o hydrogen, 20 v/o steam

burn in the FITS tank. Close examination of the trace reveals

a small amount of noise present, recognizable as a slight

waviness in the trace and in the thickness of the trace.

Figure llb shows the same trace after it was smoothed using a

Butterworth filter technique (see Appendix A). The trace

looks very much the same, except now the waviness has disappeared and the trace is much finer. Upon comparing the two

traces (Figure lic, which is an expansion of the area outlined

in a and b), it can be seen that there is a substantial difference between the two traces.

This difference is important when calculating heat fluxes

from temperature responses, which involves taking derivatives

of the temperature profile. If the trace is jagged as in

Figure lha, the derivatives will be large and variable and

unrepresentative of the physical phenomenon. The smoothed

trace in llb will produce more meaningful derivatives.

Since smoothing sometimes can distort the data, it is important to consider the effect of smoothing on the peak temperatures. Figure 12 shows a comparison of the smoothed and

unsmoothed data for a gas-temperature peak. Although smoothing attenuates the peak temperature slightly, the error is

small and within the experimental uncertainties.

18
760.0

648.9 648.910% HYDROGEN 20% STEAM

0 537.8

S426.7

'U

315.6

'UI--

204.4

93.3

0 1 2 3 4 5 6 7 8 9 10

TIME (seconds)

Figure 12. Comparison of Smoothed and Unsmoothed Data for a Gas-Temperature Peak
4. RESULTS AND CONCLUSIONS

4.1 Gas-Temperature Measurements

The gas-temperature data presented in this report are those

measured by the HBS instrumentation. The measurements from

the FITS array of 32 12-mil thermocouples were not considered

in this report, because they have a much slower response and

generally are used by the Hydrogen Behavior Program for indicating flame arrival.[8]

4.1.1 Thermocouple Comparison

As stated before, a comparison was made between two sizes of

Type K thermocouples. The response (as indicated by peak

temperature measurements) and survivability of a 0.5-mil foil

thermocouple were compared to those of a 5-mil beaded thermocouple to determine whether either kind had an advantage over

the other. It was expected that, because they had less mass.

the 0.5-mil thermocouples would have a better response but

would not survive very well compared to the 5-mil thermocouples.

However, the results did not confirm our expectations. In

general, the data did not favor either size of thermocouple

insofar as response was concerned, and only one thermocouple

(a 0.5-mil) did not survive all the burns to which it was

subjected. Figure 13 compares the responses of the two thermocouple sizes for a 12 v/o hydrogen. 40 v/o steam burn. It

can be seen that neither size has a response that is consistently better than the other.

PEAK TEMP. RISE *C

5 MIL TC 900

800 -

0.5 MIL TC 700 - < KX

600 -

500 -

400

300

200

100

0

A B C D E F

THERMOCOUPLE LOCATION

Figure 13. Thermocouple Response Comparison

20
This can be explained by the fact that the 0.5-mil thermocouples were not designed to measure gas temperatures. They

were mounted on a thin piece of phenolic; sometimes the phenolic burned off, and sometimes it did not, leading to varying responses. The phenolic also provided some degree of

protection from the burn, which the 5-mil thermocouples did

not have. On a new thermocouple probe, the 5-mil thermocouples were more likely to have a better response. However.

as the instrumentation was subjected to more burns, the phenolic burned off the 0.5-mil thermocouples, and their response

became as good or better than that of the 5-mil thermocouples.

In the future, if more HBS tests are conducted at FITS, we

will pair some 2-mil beaded thermocouples with the 5-mil

beaded thermocouples and repeat the comparison.

It was found that the peak gas-temperature measurements were

sensitive to the location of the thermocouples with respect

to the probe. Despite our efforts to ensure that all thermocouples were not in contact with or shielded by the probes,

we found after removing the probes from the tank that some of

the thermocouples had moved slightly and were indeed somewhat

shielded from the burn, either by the probe or by the thermocouple sheathing. There is a strong correlation between the

peak gas-temperature measurements from each thermocouple and

the location, with respect to the probe, of each thermocouple.

4.1,2 Peak Gas Temperatures and Initial Pressure Correction

Table 2 shows the peak gas-temperature rises for each burn as

measured by the gas-probe thermocouples. Note that these are

not actual gas temperatures but temperature rises. The actual

peak temperatures are approximately 1000C (200 0 F) higher

because the initial temperatures were about 1000C (200 0 F).

Several pieces of information can be obtained from Table 2.

First, however, the fact that each test had a different preignition pressure should be considered. Because of the way

the tank is filled, substantially different preignition pressures are obtained for cases with steam added. This results

in widely varying masses of hydrogen in the tank (even if the

volume percentage is the same), which in turn results in varying quantities of energy being released during combustion.

To correct for this. two factors must be considered.[9] One

is the amount of energy produced by the hydrogen that is

burned; the other is the flame temperature (which for these

lean burns is not dependent on initial pressure). The energy

term can be obtained from the ideal gas law, PV = nRT, but

this factor alone will overcorrect in most cases because it

does not take rate effects into account. The flametemperature factor, which accounts for rate effects, is not

so readily obtained. Work is continuing in this area.

21
Table 2

Peak Gas-Temperature Rises (OC)*

Hydrogen

Concentration (v/o)

Steam Concentration (v/o)

0 20 40

6

7

8

197

254

542

95 151

264

719 (T)

541(T)

441

384

N

9

10

1].

12

15

577

768

776

779

860

748

743(T)

694

813

1088

869

*Initial temperatures -100 0 C

(T) = Turbulence (fans on during burn)

N = No ignition

The energy factor simply adjusts the peak gas temperatures for

each burn by using a ratio of preignition pressure to a base

pressure. For massive components, in which the component's

temperature response is much slower than the temperature

response of the gas and the rate effect is thus relatively

insignificant, the energy factor alone can possibly be used

to correct for the different initial pressures. For faster

responding components, in which rate effects are important,

the energy factor alone will overcorrect; however, the energy

factor can be used as a bound. As shown in following sections, the energy factor alone can have a substantial effect.

4.1.3 Effects of Hydrogen Concentrations

Until the effect of different preignition pressures is determined, it is not feasible to draw conclusions about the

effects of steam on gas or component temperatures. Since the

hydrogen concentrations in FITS Series I are low and do not

alter the initial pressures significantly, a trend can be

defined for the effect of hydrogen on the peak gas-temperature

22
rises (Figure 14). Again, note that these are peak temperature rises; to obtain actual temperatures, the initial temperature of about 100 0 C (200 0 F) must be added. As expected.

the peak temperatures increase with increasing hydrogen percentages. It also can be seen from Figure 14 that. in general, higher peaks are recorded in the upper portion of the

tank than in the lower portion.

900 I I

800 F700

0.

wj

600 1-

UPPER TC

LOWER TC

500 I400 I300 -

/

100

I 0

6 7 8 9 10 11

% HYDROGEN (0% STEAM)

12

Figure 14. Effect of Hydrogen Concentration on Peak Temperature Rise

4.1.4 Repeatability

The gas temperatures in Table 2 do not show particularly good

repeatability. In examining each individual thermocouple's

output, it was found that the peak temperature did not occur

in any one specific location and that two identical thermocouples only 25 cm (10 in) apart could have quite different

responses. This leads to the conclusion that either the burns

in the FITS tank had somewhat random temperature distributions, or else the gas-temperature measurements were erratic.

However, the component responses were more repeatable (for

hydrogen concentrations greater than 8 v/o), as will be discussed below, and the pressures also appeared to be repeatable; this suggests that while the local environments were

23
somewhat erratic, the net effects of the burns were fairly

consistent.

4.1.5 Effects of Fans

The effect of fans on peak gas temperatures (Table 3) is

uncertain, because the gas-temperature measurements themselves

are somewhat uncertain. It appears that for the 8 v/o hydrogen, 20 v/o steam case, fans promote completeness of the

burns, thereby raising the peak gas temperatures. However,

the 10 v/o hydrogen, 20 v/o steam case apparently burns to

completion without the fans; for this case the fans had substantially less effect. This is discussed further in connection with the effect of fans on calorimeter response.

Table 3

Effect of Fans on Peak Gas-Temperature Rises

Hydrogen Thermocouple

Concentration (v/o) Probe

Temperature Rise (OC)*

Fans Off Fans On

8 Upper 264 577

538

8 Lower 47 719

541

10 Upper 748 712

10 Lower 590 743

*Initial temperatures -100 0 C

tSteam concentration 20 v/o for all burns

Another interesting point to be made about Table 3 is that,

while Figure 14 shows that the maximum gas temperatures usually are recorded in the upper portion of the tank, leaving

the fans on during the burn results in the peak temperatures

being recorded in the lower portion of the tank. This suggests that the fans suppress the buoyancy effects that are

normally present in quiescent burns.

4.2 Flat-Plate Calorimeters

4.2.1 Results

A typical temperature trace for a flat-plate calorimeter is

shown in Figure 15. The mixture is ignited at time = 0 s.

The temperature rises rapidly, peaks at about 10 s, and

24
descends gradually. Table 4 contains the peak temperature

rises for the flat-plate calorimeters for FITS Series 1.

Using the Sandia One-Dimensional Direct/Inverse Thermal

(SODDIT) Analysis Code, heat fluxes can be calculated from

the flat-plate calorimeter temperature profiles;[10] work is

continuing in this area.

392 I I I i I

356 -

o320

284

a.2248-

FW

212 --

176 I I

-10 0 10 20 30 40 50 60 70 80 90

TIME (seconds)

Figure 15. Typical Temperature Response for Flat-Plate

Calorimeter

4.2.2 Effects of Hydrogen Concentrations and Fans

As in the results for the peak gas temperatures, the effects

of steam cannot be considered until the problem of different

preignition pressures is resolved. Because the flat-plate

calorimeters have relatively fast response, rate effects must

be accounted for; that is. the energy factor alone will overcorrect the data. However the problem can be bounded by

applying the energy factor alone. In Table 4. increasing

steam concentrations increased the peak temperatures (for

complete burns, i.e., concentrations above 8 v/o) but the

energy factor (Table 5) reverses this trend. Further study

concerning the rate effects is needed before the true effect

of steam concentration can be properly evaluated.

25
Table 4

Flat-Plate Calorimeters: Peak Temperature Rises (OC)*

Hydrogen

Concentration (v/o)

Steam Concentration (v/o)

0 20 40

6

7

8

24

48

68

9 17

49

71(T)

69(T)

98

65

N

9

10,

11

12

15

70

71

88

74

98

93(T)

124

106 134

166

163

*Initial temperatures -100 0 C

(T) = Turbulence (fans on during burn)

N = No ignition

The effect of hydrogen concentrations on peak temperature

rises is shown in Figure 16, and the effect of fans is shown

in Table 6. Again, the primary observation is that for 8 v/o

hydrogen burns, the peak flat-plate calorimeter temperature

is substantially higher with the fans on, while for 10 v/o

hydrogen burns there is much less difference. This agrees

with the observations of gas temperatures and supports the

explanation that the fans make 8 v/o burns more complete but

had little effect at 10 v/o because those burns were virtually

complete even without fans. As mentioned above, gas temperatures measured by thermocouples indicated local variations in

the combustion. Since the flat-plate calorimeters have more

thermal mass, have smaller surface-area-to-volume ratios, and

are strongly coupled by thermal radiation to the gas throughout the vessel, the temperatures of the flat plates are more

representative of an average effect of the gas. Thus. the

flat-plate data can be used to infer that the net effect of

fans at 10 v/o is to increase the rate of energy transfer to

the walls of the vessel during and after the burn. This

26
results in lower peak temperatures, both in the gas and for

the flat plates. This effect is present in the 8 v/o cases

also but is masked by the improved combustion completeness.

Table 5

Flat-Plate Calorimeters: Peak Temperature Rises (OC)*

(Energy Factor Applied)

Hydrogen

Concentration (v/o)

Steam Concentration (v/o)

0 20 40

6

7

8

24

46

66

7 10

37

53(T)

51(T)

54

37

N

9

10

11

12

15

67

67

83

91

99

72

68(T)

66

96 89

113

*Initial temperatures -100 0 C

(T) = Turbulence (fans on during burn)

N = No ignition

4.2.3 Repeatability

From Table 4 it can be seen that, for the more complete burns

(above 8 v/o hydrogen), the peak temperature-rise data for

the flat-plate calorimeters are more repeatable than the gastemperature data. This indicates that, although the gas temperature measurements are not always repeatable, the responses

of components are repeatable. Perhaps the thermocouples are

responding to local variations in the gas temperatures, and

the more massive component surfaces are more indicative of

the average net effects. Thus it may prove more meaningful

to evaluate the temperature environment by measuring the

response of components (such as calorimeters or heat-flux

27
gages) instead of trying to measure the gas temperatures

directly. (This applies only to environmental temperature

measurements; the pressure measurements appear to be repeatable.)

120 1 1 1

100

0

o 80

w

4 4o

w

ILl

20.

- I I I I I

0 7 8 9 10 11 12

% HYDROGEN (0% STEAM)

Figure 16. Effect of Hydrogen Concentration on Peak FlatPlate Calorimeter Temperature Rise

Table 6

Flat-Plate Calorimeters: Effect of Fans on

Peak Temperature Rises

Hydrogen t Temperature Rise (OC)*

Concentration (v/o) Fans Off Fans On

8 49 71

69

10 98 93

*Initial temperatures -100 0 C

tSteam concentration 20 v/o for all burns

28
4.3 Cube Calorimeters

The cube calorimeters provide a comparison of components having the same geometrical configurations but different thermal

capacities. Figure 17 shows typical temperature traces for

the hollow and solid cube calorimeters, and Figure 18 shows

their peak temperature rises for varying hydrogen concentrations (0 v/o steam).

The effect of fans on peak temperature rise is shown in

Table 7. Note that the cubes do not have a lower peaktemperature rise for the 10 v/o hydrogen case with fans; this

is different behavior from the flat-plate calorimeters.

Because the cubes are more massive and therefore slower

responding, their temperature response does not follow the

gas temperature. It lags behind the gas temperature and does

not reach a well-defined peak but rather reaches a given temperature level slowly and remains there. Thus while the fans

may cause the components to heat up more quickly, they do not

have an appreciable effect on the peak temperature of the

more massive components. Concerning repeatability, the

discussion of the flat-plate calorimeters also applies to the

cube calorimeters.

12 5 i I I " I I I

HOLLOW CUBE CALORIMETER

120 -

115 -

U.

W 110 - I-.

Wc 105 - CLSOLID CUBE CALORIMETER

100 - 1/8" BELOW SURFACE

901

-10 0 10 20 30 40 50 60 70 80 90

TIME (seconds)

Figure 17. Typical Temperature Responses of Hollow and

Solid Cube Calorimeters

29
35

30 - -9 I25 -

U,

E

Uj

wI4

20 I4.-

/

* /

A - - - -

... - HOLLOW CUBE

CALORIMETER

-SOLID CUBE

CALORIMETER

15

10

5

0

6 7 8 9 10 11

% HYDROGEN (0% STEAM)

12

Figure 18. Cube Calorimeters: Effect of Hydrogen

tion on Peak Temperature Rise

ConcentraTable7

Cube Calorimeters: Effect of Fans on Peak Temperature Rises

Hydrogen Cube Temperature Rise (OC)*

Concentration (v/o) Calorimeter Fans Off Fans On.

8 Solid 3 6

5

8 Hollow 16 33

32

10 Solid 7 7

10 Hollow 39 41

*Initial temperatures -100 0C

tSteam concentration 20 v/o for all burns

30
4.4 Flux Gages

As expected, some problems were encountered with the heat-flux

gages. Because of these problems, which are described below,

the quantitative data from the gages will not be presented.

(Flat-plate calorimeter heat-flux calculations will be presented in a future report.) However, several observations

can be made by looking at the output from the gages.

The ellipsoidal gage posed difficulties in that it required a

continuous air purge to keep the sensor dry; this air purge

interfered with the pressure inside the tank. Also, the

extra tank penetrations necessary for this air purge often

leaked, causing further problems. And finally, despite the

air purge, water from the steam preheat process eventually

seeped into the gage, shorting it out.

The other two gages did not have air purges but posed other

problems. These gages are very sensitive to any water on

their sensing surface. Although an attempt was made to ensure

that the tank walls and equipment were kept above the saturation temperature, this was not always achieved. Periodically,

no output was produced by the gages, possibly indicating that

some condensation was formed on the foil surfaces of the

gages. There is a correlation between this phenomenon and

the temperature of the inside wall of the tank.

In addition, these gages were somewhat fragile. It is unclear

whether the combustion pressure pulses damaged the foils, but

there was some degradation of the absorptive coating, which

was probably a combined effect of heat and moisture. One of

the gages failed (open circuit) in the last and most severe

burn (15 v/o hydrogen, 20 v/o steam).

Although we do not consider the heat-flux gage data from these

tests reliable enough to report, much was learned about measuring heat fluxes in the FITS tank; this experience will be

useful in future attempts to measure heat flux.

4.5 Solenoid Valve

Figure 19 shows a typical temperature profile recorded for

the solenoid valve. Table 8 gives the temperatures at 90 s

after the burn was initiated. (The data-acquisition system

was limited to recording data for 90 s after ignition.) The

solenoid valve temperatures had not peaked yet but were nearly

level, indicating these temperatures are probably within a

few degrees of the actual peak.

The electrical operation of the valve was verified before and

after the test series by connecting a 40-psi air line to the

pressure port on the valve, then applying ac power several

times and listening for the air release (exhaust). The valve

31
operated properly in all tests. This procedure could be performed only when the top of the tank was removed to provide

access to the valve. During the test series there was not

sufficient time to remove the top, so the operation of the

valve was checked between burns by applying ac power to the

valve and monitoring the current into the valve. The current

before the test series was 186 mA; after the first burn it

increased to 195 mA and remained at that level throughout the

rest of the test series. (The current on a new, identical

solenoid valve was measured at 193 mA.) This change in current did not appear to have any effect on the operation of

the valve.

114

112

_110

108

W 106

L.

104

102

SOLENOID VALVE

INSIDE SURFACE OF COVER PLATE

12% HYDROGEN, 0% STEAM

S II II ]I I I I

I

100

-1 0 0 10 20 30 40 50 60 70 80 90

TIME (seconds)

Figure 19. Typical Temperature Response of Solenoid Valve

4.6 Other

4.6.1 Mixing Fans

The mixing fans were the only "components," other than the

solenoid valve, installed in the tank; in order to gain more

experience in testing components in a hydrogen-burn environment, it was decided to monitor the mixing fans' temperature

response. Two foil thermocouples were attached to the outer

case of each fan motor, so that one thermocouple was on a

surface that faced toward the centerline of the tank and the

other was on a side surface perpendicular to the first surface.

32
Table 8

Temperature* of Solenoid Valve 90 Seconds

after Burn Initiation

Hydrogen

Concentration (v/o)

Steam Concentration (v/o)

0 20 40

6

7

8

104

107

109

102 103

107

Ill(T)

110(T)

117

110

N

9

.10

ll

ill

112

112

1,12

112

116

113 (T)

123

12

15

117

122

125

*Temperature of inside surface of cove

perature -1000 C

(T) = Turbulence (fans on during burn)

N = No ignition

r plate: initial temFigure 20 shows the difference in temperature response for

the two thermocouple locations. The surface facing across

the tank reached a higher peak temperature but cooled rapidly

until it agreed fairly well with the temperature at the perpendicular surface. This is indicative of the longer beam

lengths (and greater heat transfer) seen by the surface facing

across the tank and demonstrates the effect that component

orientation and location have on component temperature

response.

4.6.2 Cable Samples and Terminal Blocks

As stated previously, the cable samples and terminal blocks

were included in the test series for visual inspection purposes only. The terminal blocks showed little deterioration

after being exposed to six burns with hydrogen concentrations

33
less than 9 v/o. There was some corrosion and slight discoloration of the unplated metal parts (i.e.. screws and

rivets); this was likely caused by the wet environment.

155

140

W

cc

0.

I125

110

95

80i-

-10 0 10 20 30 40 50 60 70 80 90

TIME (seconds)

Figure 20. Surface Temperature Response of Mixing Fan

However, after being subjected to 23 burns, some with hydrogen

concentrations higher than 9 v/oy the terminal blocks did

show damage. Some of the smaller plastic pieces were melted.

and the main block bodies were discolored. There was more

severe corrosion of the smaller metal parts; again, this is

likely due to extended exposure to a wet environment.

The cables tested included both Class IE-qualified and

unqualified cable samples. Although a detailed investigation

of cable survival was beyond the scope of these tests, it was

observed that the unqualified samples appeared to have sustained more damage than the qualified samples.

The cable samples were mounted in the test vessel such that a

portion of each cable was fastened to a metal probe and the

rest was suspended in space (Figure 21). The cable portions

that were attached to the probe sustained significantly less

damage than the portions suspended in space. This indicates

34
that the probe provided some degree of protection from the

burns (possibly by acting as a heat sink).

ir

Figure 21. Cable Samples

35
5. SUMMARY OF FINDINGS AND CONCLUSIONS

As part of the HBS Program, a series of hydrogen-burn experiments was conducted at the FITS facility. Data from 21 combustion tests (burns) were recorded, reduced, and analyzed

from instrumentation measuring both gas and component temperature responses. Some findings, such as (1) increasing hydrogen concentrations increased peak temperatures and (2) thinwalled components responded faster and reached higher temperatures than thick-walled components, were expected. Some

unexpected findings (e.g., smaller thermocouples did not

necessarily respond better than larger ones) were also

encountered. The effect of steam concentration on temperatures cannot be determined until the problem of different

preignition pressures is resolved. Fans appeared to promote

more complete combustion. A Class IE-qualified solenoid valve

survived all burns in the test series; however, a direct conclusion regarding hydrogen-burn survivability in a reactor

containment cannot 'be drawn from this data because of the

volume scaling factor.

36
REFERENCES

1. W. H. McCulloch, A. C. Ratzel, S. N. Kempka. D. T.

Furgal, and J. J. Aragon, Hydrogen Burn Survival: Preliminary Thermal Model and Test Results, SAND82-1150.

2. H. Tamm, D. D. -S. Liu, W. Harrison, "The WNRE Research

Program on Hydrogen Behavior in Nuclear Reactor Containments." presented at the Workshop on the Impact of

Hydrogen on Water Reactor Safety, Albuquerque. NM,

January 26-28, 1981.

3. D. D. S. Liu, R. MacFarlane, and L. J. Clegg, "Some

Results of WNRE Experiments on Hydrogen Combustion."

presented at the Workshop on the Impact of Hydrogen on

Water Reactor Safety, Albuquerque, NM, January 26-28,

1981.

4. Gardon. Robert, "An Instrument for the Direct Measurement

on Intense Thermal Radiation." The Review of Scientific

Instruments, Vol. 24. No. 5, May 1953.

5. Brookley. Charles E., "The Circular Foil Heat Flux Gage,"

Thermogage, Inc., Frostburg, Maryland.

6. S. F. Roller and S. M. Falacy, "Medium Scale Combustion

Tests of Hydrogen-Air-Steam Systems," SAND82-2390C, presented at the Second International Workshop on the Impact

of Hydrogen on Water Reactor Safety, Albuquerque, NM,

October, 1982.

7. J. B. Kennedy and A. M. Neville, Basic Statistical

Methods for Engineers and Scientists, Thomas Y. Crowell

Company, Inc., New York, 1976, pp 177-181.

8. M. Berman, "H2 Research Programs." presented at the

Workshop on the Impact of Hydrogen on Water Reactor

Safety, Albuquerque, NM, January 26-28, 1981.

9. Conversation with Marty Sherman of Sandia Laboratories

on June 3, 1983.

10. B. F. Blackwell, "User's Manual for the Sandia OneDimensional Direct and Inverse Thermal (SODDIT) Code."

37
APPENDIX A

Plotting and Smoothing of HBS Data

E. A. Aronson

Reference: Sterns, S. D., Diaital Signal Analysis, Hayden

Book Co., Rochelle Park, New Jersey, 1974.

This appendix describes a set of programs to plot and smooth

HBS data on the VAX. All coding is in FORTRAN 77. Each data

file consists of a 10-character identification word, a time

channel, and 32 data channels. Each channel consists of 2048

data points. A data file is read by the following code:

CHARACTER *10 IDENT

REAL T(2048), D(2048,32)

READ (1,'(AIO)') IDENT

READ (1,'(IX,5F15.6)')(T(I).I=1,2048)

DO 10 K=1,32

READ (I,-(lX,5F15.6)')(D(I,K), I=1.2048)

Actually, the time channel is not needed because the data are

assumed to be equispaced in time. Only the start time and

time step should be required.

The input data file is specified for all programs by

ASSIGN datafile FORO01

The terminal input is assigned by

ASSIGN TT FOR005

If a new, modified, data file is created, it is written to

FOR002. The file may be named as desired by inputting an

ASSIGN before its creation or by RENAME after it has been

generated.

Plotting is done by the WEASEL package. Once an OBJ file has

been created, it is linked to WEASEL by

LINK code,'LINKWSL','LINKTK4'.

The TK4 is for the TEKTRONIX 4014. For other terminals or

plotting devices, another code must be used. All plots are

data versus time.

38
MPLOT

This code allows a quick look at the data. The data in each

channel are grouped into 256 sets of 8 adjacent (in time)

points each. For each set of 8 points, the minimum and maximum are found. The 256 minima are plotted, and the 256 maxima are overlay plotted. The result is a plot which gives a

good idea of the data shape and noise in the data.

BPLOT

This program allows a blow-up of selected regions of time.

For each channel, t7he user is queried for the time span (T1 . T2 )

to be plotted. If TI > T 2 8 a full-scale plot of only the

(T1 , T2 ) region is done.

FOUTL

This code attempts to remove "outliers" from the data. The

user is asked to provide two parameters, F > I and N > 0.

For each channel, the set of 256 minima, mi. and 256 maxima,

Mi, are computed as in MPLOT. For (N + 1) < i < (256 - N).

a set is considered to contain a candidate outlier if

mi < (miI. mi+l) (1)

or Mi > (MiI. Mi+i) (2)

If Eq. 1 is satisfied, the i-th set has a candidate minimum

outlier. If Eq. 2 is satisfied, it has a candidate maximum

outlier. If both Eqs. 1 and 2 are satisfied, the set has a

candidate minimum outlier if

(min1 + mi+ )/2 - mi > Mi - (Mi+1 + Mi_ )/2. (3)

If the sign of Eq. 3 is <, the set has a candidate maximum

outlier. If the i-th set has an outlier candidate, then it

has an outlier if

M. - mi > F [ (M. - mi) - (M. - mi) /2N (4)

If Eq. 4 is satisfied and the candidate is a minimum (maximum), the outlier point itself is the minimum (maximum) of

the 8 points associated with the i-th set. The outlier value

is set equal to the average of its immediately adjacent 2

points (of the "original" data, not the sets of data).

This method is useful for isolated outliers but questionable

if a region of adjacent points are outliers. It may be necessary to make multiple FOUTL passes on the data. Reasonable

values for the parameters seem to be F = 3 and N = 2. A

"corrected" data file is written to FOR002.

39
BUTW

This code smooths the data with a low-pass Butterworth

filter--see the reference. The Butterworth filter is defined

by two parameters.

FR - Relative frequency of the -3 dB power point of

the filter. 0 < FR < 0.5

NS - Number of filter stages, 1 < N < 5

For 2048 points, the FFT (Fast Fourier Transform) will produce 1024 frequency values. The parameter FR is the "cutoff"

frequency relative to these 1024 frequencies. For example.

FR = 0.125 puts the cutoff at the 128th frequency.

To eliminate phase (time) shift, the data are passed through

the first stage of the filter in the forward time direction

and then through the first stage again in the backward time

direction. This process is repeated for each of the NS

stages. Thus, the -3 dB point is actually attenuated by

-6 dB because of the double passes. If [Xi) is the input

data stream and {Yi) is the output,(smoothed) data stream.

then the k-th stage of the filter is implemented by

Yi = Ak (Xi + 2Xi-i + Xi-2) - BY i-i - CkYi-2" (5)

The Ak, Bk, and Ck are determined by FR and NS.

If the input FR or NS is out of the bounds given above, the

channel is not smoothed, but the "unsmoothed" channel is

written to FORO02, nevertheless.

If the data are smoothed, they are also plotted. The user

inputs the integer flag IPR and plotting time bounds. If

IPR = 1. the smooth data are plotted. If IPR = 2. the

unsmoothed data are overlay plotted on the smooth data.

Other values of IPR are not allowed. The time bounds are the

same as those given in BPLOT.

40
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W.

D.

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McCulloch

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Dandini

Furgal

King

Richards (15)

Bonzon

Berry

Bergeron

Ostrander (5)

Garner

Pound

1512

1513

1513

2513

2513

6400

6411

6427

6427

J.

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A.

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C. Cummings

N. Kempka

C. Ratzel

F. Roller

E. Shepherd

W. Snyder

E. Dingman

Berman

Marshall

41
NRC FORM 335 U.S. NUCLEAR REGULATORY COMMISSION I REPORT NUMBER (Asj,9ns by TIDC. O0d Vol No. d any)

12-841

3201,3202 BIBLIOGRAPHIC DATA SHEET N D83G 1715 3

SAND8 3- 1715 SEE INSTRUCTIONS ON THIE REVERSE

2. TITLE AND SUBTITLE 3 LEAVE BLANK

Hydrogen-Burn Survival Experiments at

Fully Instrumented Test Site (FITS) 4 DATE REPORT COMPLBTEO MONTH YEAR

December 1983 S zy zabei~th Richards 18

John J. Aragon 6ONTS6 DATE REPORT ISSUED

June 84

7, PERFORMINORGANIZATION NAME AND MAILING ADDRESS 1ln¢*u. Zop Coaa; 8 PROJECTITASK WORK UNIT NUMBER I vision 6445

Sandia National Laboratories 9 FIN OR GRANT NUMBER

P.O. Albuquerque, Box 8500 NM 87185 A-1270 A-1306

10. SPONSORING ORGANIZATION NAME AND MAILING ADDRESS (Inclue',VO CZeA Ila TYPE OF REPORT

Div. of Accident Evaluation, Ofc. of Nuclear Data

Regulatory Research, and Div. of Engineering, Ofc. of Nuclear Reactor Regulation. b, PERIOD COVEREDO,,l,,.;

U.S. Nuclear Regulatory Commission, May 1982 to June 1983

Washington, DC 20555 12. SUPPLEMENTARY NOTES

13 ABSTRACT 12W words o, .iss)

A series of hydrogen-burn experiments conducted for the Hydrogen-Burn

Survival Program is described. The experiments, executed at Sandia's

Fully Instrumented Test Site (FITS) facility, provided data concerning

the hydrogen-burn thermal environment as it relates to equipment survivability in nuclear power plants.

The test plan, instrumentation, and results are presented, along with a

brief discussion of test volume (scale) considerations. Conclusions

drawn from the results concern repeatability of the tests, the suitability of thermocouples for measuring gas temperatures, and the effects of

initial hydrogen concentrations and fans on the responses of calorimeters and components. The effect of initial steam concentration on temperature response cannot be determined because of preignition pressure

considerations.

14 DOCUMENT ANALYSIS -. KEYWORDSIOESCRIPTORS 15 AVAILABILITY

STATEMENT

Unlimited

Nuclear Safety; Hydrogen; Combustion;

Containment; Equipment Survivability 16 SECURITY CLASSIFICATION

ITs,$ 0000l

0. IDENTIFIERSIOPEN.ENDED TERMS Unclas.

Unclas. 17 NUMBER OF PAGES

IB PRICE

;I

Org. Bldg. Name Rec'd by lorg. Bldg. Name Rec'd by

1 *1 .1 _

r __

Sandia National Laboratories