NUREG/CR--4596

SAND86-0394

RP

Printed June 1986

Screening Tests of Representative

Nuclear Power Plant Components

Exposed to Secondary

Environments Created by Fires

Mark J. Jacobus

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

-1'~

~ k' 

T;-"- >r. - !7

U11 •.SU.'E''EAR. REGULATORY COMMISSION

SF29000(8-81)

- -- ~ -- - -.

NOTICE

This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United

States Government nor any agency thereof, or any of their em- ployees. makes any warranty, expressed or implied, or assumes any legal liability or 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.

Available from

Superintendent of Documents

U.S. Government Printing Office

Post Office Box 37082

Washington, D.C. 20013-7982

and

National Technical Information Service

Springfield, VA 22161

NUREG/CR-4596

SAND86-0394

RP

SCREENING TESTS OF REPRESENTATIVE NUCLEAR POWER PLANT COMPONENTS

EXPOSED TO SECONDARY ENVIRONMENTS CREATED BY FIRES

Mark J. Jacobus

Date Published: June 1986

Sandia National Laboratories

Albuquerque, NM 87185

operated by

Sandia Corporation

for the

U. S. Department of Energy

Prepared for

Division of Engineering Technology

Office of Nuclear Regulatory Research

U. S. Nuclear Regulatory Commission

Washington, DC 20555

Under Memorandum of Understanding DOE 40-550-75

NRC Fin No. A1010

Abstract

This report presents results of screening tests to determine component

survivability in secondary environments created by fires, specifically

increased temperatures, increased humidity, and the presence of

particulates and corrosive vapors. Additionally, chloride concentrations

were measured in the exhaust from several of the tests used to provide

fire environments. Results show actual failure or some indication of

failure for strip chart recorders, electronic counters, an oscilloscope

amplifier, and switches and relays. The chart recorder failures resulted

from accumulation of particulates on the pen slider mechanisms. The

electronic counter experienced leakage current failures on circuit boards

after the fire exposure and exposure to high humidity. The oscilloscope

amplifier experienced thermal-related drift as high as 20% before thermal

protective circuitry shut the unit down. In some cases, switches and

relays experienced high contact resistances with the low voltages levels

used for the measurements. Finally, relays tested to thermal failure

experienced various failures, all at temperatures ranging from 1500C to

above 3500C. The chloride measurements show that most of the hydrogen

chloride generated in the test fires is combined with particulate by the

time it reaches the exhaust duct, indicating that hydrogen chloride

condensation may be less likely than small scale data implies.

-iii/iv-

Table of Contents

Page

Executive Summary .................................................. 1

1.0 Objectives ....................................................3

2.0 Test Philosophy and Approach .................................. 4

3.0 Experimental .................................................. 5

3.1 Environment Creation and Planned Environmental Profiles..5

3.2 Component Procurement .................................... 5

3.3 Chloride Ion Measurement System .......................... 8

3.4 Quantity and Location of Components in Cabinet Tests ..... 8

3.5 Physical Configuration of Relays Tested

to Thermal Failure...................................... 8

3.6 Electrical Configuration of Components in Cabinet Tests.10

3.7 Electrical Configuration of Relays Tested

to Thermal Failure ...................................... 10

4.0 Results ...................................................... 13

4.1 Components Tested ....................................... 13

4.1.1 Switches ......................................... 13

4.1.1.1 General ................................... 13

4.1.1.2 Unpowered Switches ........................ 13

4.1.1.3 Powered Switches......................... 15

4.1.1.4 Humidity Exposure of Switches ............. 15

4.1.1.5 Applicability of Switch Data to

Other Components .......................... 15

4.1.2 Relays ........................................... 18

4.1.2.1 General ................................... 18

4.1.2.2 Unpowered Relays .......................... 18

4.1.2.3 Powered Relays ............................ 19

4.1.2.4 Humidity Exposure of One Relay ............ 19

4.1.2.5 Relays Tested to Thermal Failure .......... 19

4.1.2.5.1 Agastat GPI Relays ............. 19

4.1.2.5.2 General Electric HMA Relay ..... 35

4.1.2.6 Applicability of Relay Data to

Other Components .......................... 35

4.1.3 Meters ........................................... 40

4.1.3.1 General ................................... 40

4.1.3.2 Applicability of Meter Data to

Other Components .......................... 40

4.1.4 Chart Recorder ................................... 41

4.1.4.1 General .................................. 41

4.1.4.2 Applicability of Chart Recorder Data.

to Other Components ...................... 41
Table of Contents (continued)

4.1.5 Electronic Counter ............................... 43

4.1.5.1 General .................................. 43

4.1.5.2 Applicability of Counter Data to

Other Components ......................... 45

4.1.6 Other Electronic Equipment ....................... 45

4.1.6.1 General .................................. 45

4.1.6.2 Applicability of Data to

Other Components ......................... 48

4.2 Summary of Component Data Applicability to

Other Components ........................................ 51

4.3 Chloride Ion Measurements.............................. 54

4.3.1 Chloride Ion Analysis of the Particulate

and Residue Samples .............................. 54

4.3.2 Chlorides Ions in Exhaust as a Function of Time..55

5.0 Conclusions .................................................. 58

6.0 References ................................................... 60

Appendix A--Chloride Ion Measurement System ....................... 61

-vi-
List of Figures

FiGure Pag e

1 General Arrangement Drawings for Tests Run at Sandia .............6

2 General Arrangement Drawing for Tests Run at Factory Mutual ....... 7

3 Typical Configuration of Relay in Environmental Chamber ........... 9

4 Schematic for Relays in Cabinet Tests ............................ 11

5 Schematic for 4PDT Relays Tested in Environmental Chamber ........ 12

6 Polarized Particulate Between Adjacent Terminals of Switch ....... 15

7 Load Current to Switch in Test 4 ................................. 16

8 Load Current to Switch in Test 5 .................................. 17

9 Air Temperatures Inside and Outside of Relay in Test 4 ........... 20

10 Load Current to Relay in Test 4 .................................. 21

11 Load Current to Relay in Test 5 .................................. 22

12 Coil and Chamber Temperatures for First Thermal Failure Test ..... 24

13 Contact #2 Leakage Current for First Thermal Failure Test ........ 25

14 Coil Current for First Thermal Failure Test ...................... 26

15 Motor Starter Current for First Thermal Failure Test ............. 27

16 Shorted Wires in the Socket from the First Thermal Failure Test..28

17 Coil and Chamber Temperatures for Second Thermal Failure Test .... 29

18 Motor Starter Current for Second Thermal Failure Test ............ 30

19 Contact #1 Load Current for Second Thermal Failure Test .......... 31

20 Coil Current for Second Thermal Failure Test ..................... 32

21 Contact #2 Leakage Current for Second Thermal Failure Test ....... 33

22 Melted Contact Support from Second Thermal Failure Test .......... 34

23 Coil and Chamber Temperatures for Third Thermal Failure Test ..... 36

24 Coil Current for Third Thermal Failure Test ...................... 37

-vii-
List of Figures (continued)

25 Load Current for Third Thermal Failure Test ...................... 38

26 Post-test Photograph of HMA Relay After Fire Occurred ............ 39

27 Coil Wires Shorted Together to Cause Fire ........................ 39

28 Temperature Near Strip Chart Recorder in Test 3 .................. 42

29 Failed Slider Mechanism of Strip Chart Recorder .................. 43

30 One Location of Leakage Currents on Counter Circuit Boards ....... 44

31 Temperature Near Counter in Test 4 ............................... 46

32 Temperature Near Power Supply in Test 2 .......................... 47

33 Average Temperature Near Power Amplifier in Test 2 ............... 49

34 Temperature Near Oscilloscope 4-channel Amplifier in Test 2 ...... 50

35 Chloride Concentration in Exhaust Duct vs Time for Test 3 ........ 56

A-1 Chloride Ion Measurement System ................................. 62

-viii-
List of Tables

Table Page

I Test Matrix for Components in Cabinet Tests ....................... 8

2 Cabinet Test Descriptions ......................................... 9

3 Powered Components in Cabinet Tests .............................. 10

4 Summary of Results of Unpowered Switches ......................... 14

5 Summary of Component Failure Modes ............................... 52

6 Pertinent Data for Chloride Ion Collection ....................... 57

- ix/x-

Executive Summary

During a nuclear power plant fire, numerous safety-related components

may be exposed to secondary environments created by the fire. These

environments include increased temperature levels, increased humidity

levels, and the presence of particulates and corrosive vapors. Past

accounts of fires have reported extensive damage by secondary environments

created by fire, but none state whether any electrical equipment was

damaged sufficiently to prevent it from performing satisfactorily.

Consequently, this study was undertaken to screen the components

considered to be most vulnerable to secondary environments created by

fire. Also, temperature measurements were made at numerous locations, and

chloride concentrations of the room exhaust were monitored in several of

the tests to help characterize the fire environments.

Twenty-four switches, thirteen meters, five relays, two strip chart

recorders, two electronic counters, one power supply, one power amplifier,

and one oscilloscope amplifier were tested in actual fire environments

created by burning cabinets in a room. The component locations and

orientations were varied and some components were installed with

protective covers removed. In addition, three relays were tests to thermal

failure in an environmental chamber. The relays were exposed to step

increases in temperature level until failures were observed.

Results show actual failure or some indication of failure for the

strip chart recorders, the electronic counters, the oscilloscope

amplifier, and the switches and relays. The first chart recorder tested

had the covers removed to increase the severity of the environment and it

failed to operate after the test. The failure resulted from the

accumulation of particulates on the pen slider mechanisms and

functionality could not be easily restored by cleaning the sliders. A

second chart recorder was tested in a panel-mounted configuration with all

covers intact. It experienced significantly less particulate accumulation

on the pen sliders. However, one of the three pens did not work properly

after the test, although functionality was easily restored by exciting the

malfunctioning channel with a rapidly changing voltage which was

sufficient to clean off the light particulate accumulation.

The first electronic counter tested had the covers removed and

experienced heavy particulate deposition, but continued to function

normally after the fire. Subsequently, the counter was exposed to a high

humidity environment to simulate high humidity that may be encountered

during or after a fire. The electronic counter experienced leakage

current failures on two different circuit boards after the humidity

exposure.

The oscilloscope amplifier tested experienced thermal-related drift as

high as 20% before thermal protective circuitry shut the unit down.

Switches and relays experienced high contact resistances in some cases

with the low voltage levels used for the measurements.
Finally, the relays tested to thermal failure experienced various

failure modes, all at temperatures ranging from 150 0 C to above 350 0 C.

Two Agastat GPI relays tested both had failures associated with the relay

sockets warping severely. Both short circuits and open circuits were

observed in the sockets. One additional failure of the Agastat relays was

a melted contact support on the contact carrying a load current. One

General Electric model HMA relay had its coil lead wires shorted above

3500 C, resulting in a fire in the test chamber.

The results show that most components survived the environments

created by the cabinet fires. Failure modes for many of the components

considered to be most likely to malfunction during a fire were tested

either directly or indirectly. The one notable exception identified is

high voltage breakdown which could occur on motor control centers and

switchgear.

Several additional secondary environments created by fire remain to be

addressed. These include the following: 1) direct spray from

suppression activities, either manual or automatic, 2) response of cool

components to steam exposure resulting from from suppression activities

(although high humidities were addressed by the humidity exposures,

relatively cool components were never exposed to rapidly changing humidity

which would likely cause condensation), and 3) hydrogen chloride/humidity

interactions (condensation) which might occur in certain circumstances.

2
1.0 OBJECTIVES

Accounts of several past fires [1-9] have reported significant levels

of damage caused by secondary environments created by fire, primarily as a

result of hydrogen chloride generated by burning polyvinyl chloride

(PVC). Little mention of thermal damage is included in these reports with

none indicating whether any electrical equipment exposed to the secondary

environments created by fire actually failed electrically. Clearly, much

electrical equipment has required cleaning or replacement because of fire

damage with the great New York telephone fire [4] a significant example;

millions of switches and relays were cleaned and much equipment was

replaced. The main objective of this work was therefore to assess the

functionality of representative nuclear power plant components when

subjected to secondary environments created by fire. The fire

environments were established by other test programs, specifically a

cabinet fire test program run by Sandia National Laboratories [10,11],

conducted in part at Sandia and in part at Factory Mutual Test Center.

An additional objective of this work was to establish the secondary

environments created by fire that power plant components could be exposed

to as a result of the cabinet fires. To accomplish this additional

objective, temperatures were measured throughout the fire test rooms and a

system was developed to measure the amount of chlorides (expected to be

mainly hydrogen chloride) leaving the room in the ventilation duct.

This report documents the tests conducted and the data obtained for

component functionality before, during, and after the tests and the data

obtained for the chloride measurements.

3
2.0 TEST PHILOSOPHY AND APPROACH

The basic premise for the tests run was that some components may be

easily damaged by exposure to secondary environments created by fire.

Secondary environments include increased temperature levels, increased

humidity/ moisture levels, and exposure to particulates and corrosive

vapors generated by the fire. A report prepared by NUS Corporation (12]

as a subcontract to Sandia National Laboratories judged components for

their potential for damage by secondary environments created by fire.

Each category of component was ranked from 0.00 to 1.00 based on criteria

for equipment functionality and equipment damageability. The top-ranked

components were thus considered most likely to fail when exposed to

secondary environments created by fire. The top fourteen ranked

components and their ranking are included here for completeness and are,

in order:

Egui'ment T_)p_ Relative Score

Recorders 0.79

Logic Equipment 0.77

Controllers 0.71

Power Supplies 0.67

Meters 0.61

Solid State Relays 0.60

Electromechanical Relays 0.59

Transmitters (Pressure, Level, Flow) 0.50

Hand Switches/Pushbuttons 0.50

Battery Chargers/Inverters 0.49

Motor Control Centers 0.49

Switchgear 0.49

Batteries 0.44

Temperature Switches 0.41

Components were selected for testing based on this ranking and the

additional criteria of component usage in nuclear power plant safety

systems (based primarily on one selected nuclear power plant) and what

components were on hand or readily available. Components were tested in

different configurations (covers removed or intact, different

orientations, different locations, etc.) with some powered and some not

powered. Different components had different expected failure modes and in

some cases attempts were made to make the expected failure modes more

likely (for conservatism or to represent other components). For example,

the covers on some components were removed to allow more penetration of

the environment into the component.

4
3.0 EXPERIMENTAL

3.1 Environment Creation and Planned Environmental Profiles

The components were tested in environments created by a burning

cabinet in a room with the exception of three relays which were tested to

their thermal failure limits in an environmental chamber. Some of the

components tested in the actual fire environments were subsequently

subjected to humidity environments in another environmental chamber. The

reason for exposing the components in the humidity chamber was to try to

account for the potential effects of high humidity during or after a

fire. High humidity can be created by any combination of the following:

high humidity in purge air used to remove smoke from the burning room,

generation of moisture as a combustion product, and humidity created by

water suppression equipment used on the fire. In the cabinet fire tests,

the only real contributor to increased humidity was the combustion process

since the ambient humidity was relatively low during all of the tests and

no water suppression was ever used.

A description of the facilities where the fire tests were conducted,

as well as comprehensive data for the room environment (temperatures, gas

species concentrations, heat flux measurements, smoke density

measurements, etc.) may be found elsewhere [10,11]. General arrangement

drawings are shown in Fig. 1 for the tests run at Sandia and in Fig. 2 for

the tests run at Factory Mutual.

The environmental chamber used for the three relays tested to thermal

failure was a chamber equipped to control temperature to levels

significantly higher than expected failure levels for the relays. The

purpose of the environmental chamber testing was to test components to

thermal limits. Failure temperatures can then be compared with actual

temperatures from fires to aid in establishing thermal margins. The

humidity chamber used to test some components was equipped to control both

temperature and humidity.

No specific profiles could be planned for the components put in the

cabinet fire tests. Rather, the components were exposed to whatever

environment was created by each fire.

The environmental profile planned for testing the three relays to

establish their thermal failure limits was to begin by ramping the test

chamber up to 50 0 C and then stepping the temperature up by 10 C every

10 minutes.

3.2 Component Procurement

The switches, meters, and chart recorders tested were obtained as

excess inventory of components which had been initially intended to go

into actual service in nuclear power plants. The relays tested were

obtained directly from the suppliers and are effectively identical to

Class 1E qualified relays sold to nuclear power plants, although the

relays were not specifically procured to 1E specifications. The major

difference for class 1E relays is the amount of paperwork provided and in

some cases more controls on the materials used for construction and/or a

5
24'

U, Vertical

Cabinat

Door

(a)

A

Cu

I

MItered

C461net

stndard

Denabboard

L Doo r

(b)

Fig. 1 General Arrangement Drawings for Tests

(a) Tests 1 and 2 (b) Test 3

Run at Sandia

6
T Lii u;n.Te :Ist5

-I

-.- I

Miltered

Penchbo ard

0

'4-

4J1

LI] Burn Cab.

Test 4

I13 Sectdr 1

Corner Cab.

Double Hay

Remote Cabinet

Fig. 2 General Arrangement Drawing for Tests 4 and 5

Run at Factory Mutual
separate production lot to insure traceability. The remaining components

were selected from available equipment at Sandia and were chosen in an

effort to establish whether generic types of equipment might be vulnerable

to fire environments. The particular equipment chosen has no direct

relationship with equipment used in power plants but does have similar

kinds of subcomponents. For example, although amplifiers do not appear on

the component ranking list, they were chosen to test because they have

subcomponents similar to some components on the list. Since the purpose

of the component tests was to screen component vulnerability to secondary

environments created by fire and not to test or qualify particular

components, the decision to use available generic components was

justified. No evidence was found before or after testing to indicate that

the observed survival or failure of components would be any different for

pedigreed equipment. In fact, the equipment tested represents components

normally installed in benign power plant control areas with very little

special qualification required (primarily seismic and some aging

considerations).

3.3 Chloride Ion Measurement Syste

The system used to measure chloride ions in the room exhaust is

described in Appendix A.

3.4 Quantity and Location of Components in Cabinet Tests

A test matrix for components tested in cabinet tests is given in Table

1 with a description of each test in Table 2. Components were positioned

at different locations throughout the room. The individual component

locations and model numbers may be found in the results section 4.0.

3.5 Physical Configuration of Relays Tested to Thermal Failure

The relays tested in the environmental chamber were positioned

vertically on a flat metal base in the chamber. The base was isolated

from direct contact with the heated wall by ceramic standoffs. A typical

installation is shown in Fig. 3.

Table I Test Matrix for Components in Cabinet Tests

Test Number *# #2 #3 #4 #5

Switches 2 3 0 10 9

Meters 4 4 0 3 2

Relays 0 0 0 3 2

Chart Recorder 0 0 1 1 0

Electronic Counter 0 0 1 1 0

Power Supply ** 0 1 *** 0 1 *** 1 *

Power Amplifier 0 1 0 0 0

Oscilloscope Amplifier 0 1 0 0 0

* See Table 2 for a description of the tests.

•** Some components also include power supplies.

• ** The same power supply was tested each time.

8
Table 2 Cabinet Test Descriptions

Test Test Number in

Number Refs. 10 and 11

1 PCT 1

2 PCT 2

Description of Test

Unqualified cable in vertical cabinet with

closed doors. Peak HRR * 185 kW. Duration 40

minutes. Max. temp. in room 60 0 C.

Unqualified cable in vertical cabinet with

open doors. Peak HRR 995 kW. Duration 15

minutes. Max. temp. in room 160 0 C.

Unqualified cable in benchboard cabinet with

open doors. Peak HRR 791 kW. Duration 20

minutes. Max. temp. in room 2100 C.

Unqualified cable in benchboard cabinet with

open doors. Peak HRR 860 kW. Duration 20

minutes. Max. temp. in room 125 0 C.

Unqualified cable in vertical cabinet with

no doors. Peak HRR 620 kW. Duration 20

minutes. Max. temp. in room 66 0 C.

3 PCT 5

4 FM 4

5 FM 5

* HRR-Heat Release Rate

Fig. 3 Typical Configuration of Relay in Environmental Chamber

9
Table 3 Powered Comoonents in Cabinet Tests

Test

Number

Component

2 * Power Supply

2 Power

Amplifier

2 4-channel

~nm~l If4=V.

Descrition of

Powering

115 Vac line for

main power.

115 Vac line for

main power; dc

input voltage

Same as power amp.

Description o

Monitoring

Output voltage for maintaining

set value.

Output voltage for maintaining

correct multiple of dc input

voltage.

Same as power amp.

3 Counter 115 Vac line for None continuously; checked self

main Rower, test immediately after fire,

4 Switch 115 Vac, 3 A load Load current for continuity;

on one set of Adjacent contact for leakage

contacts, current.

4 Counter Same as counter in test #3.

4 Relay #1 115 Vac, 3 A load Coil current, load current,

on one set of and adjacent contact leakage

contacts; 115 Vac current.

to coil.

4 Relay #2 115 Vac to coil. Coil current.

4 Power Supply Same as power supply in test #2.

5

5

5

5

Switch

Relay #1

Relay #2

Power Supply

Same as switch in test #4.

Same as relay #1 in test #4.

Same as relay #2 in test #4.

Same as power supply in test #2.

* See Table 2 for description of tests.

3.6 Electrical Configuration of Components in Cabinet Tests

Many of the components (e.g. meters, recorders) were installed in the

room without any power or monitoring during the test. Those that were

powered and/or monitored are outlined in Table 3. An electrical schematic

for the powered and monitored relays is shown in Fig. 4. The schematic

for the powered switches was identical except the coil was not present.

3.7 Electrical Configuration of Relaya Tested to Thermal Failure

The relays tested to thermal failure were powered, loaded, operated,

and monitored during the tests. A 115 Vac line source was used to operate

the coils and selected contacts were loaded with a 115 Vac load of

nominally 3 amps or a 115 Vac motor starter. Different contacts were

monitored for leakage currents, contact resistances, and relay operability

verification. Two of the relays tested were four-pole, double-throw

(4PDT) relays and one was double-pole, double-throw relays (DPDT). The

circuit diagram for the 4PDT relays is shown in Fig. 5. The circuit

diagram for the DPDT relay was very similar to Fig. 5, except with two

less contacts.

10
0-300V

T

TRANSDUCER

FUSE 115V AC

SOURCE R

RELAY UNDER

TEST / /0 I

I"

'-a'-a

120C) 400

0-4A

TRANSDUCER

0-10A

TRANSDUCER

Fig. 4 Schematic for Relays in Cabinet Tests
? 11

qjIFlf$

OL CM4L

RELAY

UNDER

TUT?

'-a

DL CHI4L

DL CHI

LEOI)4

R - RELAY (ON DATALOGOIR)

DL * DATALOQGGE

CH *CHANNEL

": * 4I

I. LOW

Fig. 5 Schematic for 4PDT Relays Tested in Environmental Chamber
4.0 RESULTS

The results presented in this section are organized by component. The

generic components from the ranking described in section 2.0 which have

similar expected failure modes to the tested component are also

indicated. For example, leakage currents between the terminals of a

terminal block and between the terminals of a switch or relay are expected

to be governed by the same phenomenon. Consequently, although terminal

block leakage currents were not directly tested, they were indirectly

tested by the monitoring of leakage currents on relays and switches.

4.1 Components Tested

4.1.1 Switches

4.1.1.1 General

The switches were tested in various orientations with some panel

mounted in a cabinet with an open back, some mounted on their sides to

allow more particulate deposition in the contact area, and some put

upright on horizontal surfaces. The amount of particulate deposition

varied significantly with different tests, with ventilation rate and room

size apparently the most important considerations with a given size fire.

With higher ventilation rates and the larger room, much less particulate

was deposited on the switches. In fact, the switches in test 5 were found

to be virtually free of particulate. The particulate which did appear in

test 5 was very light and could be removed with very little effort (light

blowing or even just picking up the switch). In contrast, the lower

ventilation rate of test 4 produced more particulate on the switches. The

switch that was powered in test 4 was noted to have particulate polarized

between adjacent powered and grounded terminals as shown in Fig. 6;

similar behavior was not noted in test 5.

The switches experienced varying degrees of corrosion, with more

severe corrosion after aging for days to weeks after the tests. One

switch that was exposed in the humidity chamber for 12 days at 70%

humidity appeared quite corroded with the appearance of rusting in the

contact areas. In no case did the corrosion cause any noted malfunctions

except for some high contact resistances as discussed in Section 4.1.1.4.

4.1.1.2 Unpowered Switches

The unpowered switches tested are summarized in Table 4. None of the

switches were damaged sufficiently by the fire to prevent normal operation

except that a few contacts required ac voltage stresses of up to 15 volts

to allow them to start conducting (15 V was required on only one set of

contacts). An application in a power plant using a switch (may be

extended to a relay) in a low voltage instrumentation circuit such as an

RTD circuit (typically 4 Vdc) or a thermocouple circuit (typically mV

level signals) could potentially fail under these circumstances. No

effort has been made to find out if any power plants have switching

devices in any of these circuits, but it is considered unlikely. Further,

the switches which were found with the high contact resistances were of

larger varieties (more than 5 A contact ratings typical); smaller rated

switches which were tested were effectively enclosed and did not exhibit

any of the high contact resistances.

13
Table 4 Summary of Results of Unpowered Switches

Test Manufacturer

and Model

1 General Electric

SBM

1 General Electric

SBM

Location *

Single Bay

cabinet

Above burn

cabinet

Selected Measurements Recorded

Maximum CR

test--down

Maximum CR

test.

to

of

of

14

17

65 milliohms after

after operating.

milliohms after

2 General Electric Single Bay Maximum CR of 60 milliohms after

CR2940 cabinet test--down to 22 after operating.

2 General Electric Adjacent Maximum CR of 20 milliohms after

SBM cabinet test.

2 General Electric Above burn Maximum CR of 130 milliohms after

SBM cabinet test--down to 60 after operating.

4 General Electric Left bay Maximum CR of 26 milliohms before

SB3 corner cab. test--after test similar

4 General Electric Right bay CRs ok after test.

SBM corner cab.

panel mount

6' high

4 Electroswitch Left bay Maximum CR of 8 milliohms before test

Series 20 corner cab. Two contacts open after test--ok

panel mount after stress with low ac voltage.

6' high

4 Electroswitch Top of Two CRs high after test--ok after

Series 40 corner cab. switch operations.

9' high

4 General Electric Sector 1 CRs ok after test.

SBM 4' high

4 General Electric Adjacent CRs ok after test.

SBM cab. 3' high

4 Stacoswitch Sector 1 CRs ok after test.

101MR 4' high.

4 Stacoswitch Left bay CRs ok after test.

101MR corner cab.

bottom.

4 Stacoswitch Mitered CRs ok after test.

101MR benchboard

cab. switch

surface

5 General Electric

SBM (4)

Stacoswitch

lOl (2)

Electroswitch

Series 20 (1)

Series 40 (1)

Various switches located away from fire--all

still looked like new after test--high ventilation

rate virtually eliminated particulate deposition.

Specific locations--Sector l--4'high; corner cab.,

panel mount; top of remote cab.; top of corner

cab.; and top of benchboard cab.

* See Fig. 1 for locations in tests 1-2 and Fig. 2 for tests 4-5.

** CR-contact resistance

14
Fig. 6 Polarized Particulate Between Adjacent Terminals of Switch

4.1.1.3 Powered Switches

One switch was powered and monitored during each of tests 4 and 5.

Both were located about four feet from the floor at sector 1 (see Fig. 2).

The ac supply voltage remained between 108 and 116 Vac in both tests. The

load current to the switch in test 4 is shown in Fig. 7 and to the switch

in test 5 is shown in Fig. 8. Both show no evidence of the switch failing

to carry its load. Leakage current for the switches never reached the

level detectable by the ac current sensors used in the tests (0.25 mA) and

therefore the data is not presented. Contact resistances and insulation

resistances showed no evidence of problems except one of the contacts of

the switch in test 4 took about 15 Vac stress to get a normal value in the

milliohm range (original value was about 100 kohms).

4.1.1.4 H~umidity Exposure of Switches

One switch from test 4 and one from test 1 were put in a humidity

chamber at about 27 0 C (80 0 F) and 70% relative humidity for about 12

days to see if humidity exposure at moderate levels for prolonged periods

following exposure to fire environments would cause any equipment

operability problems. Neither of the switches exhibited any adverse

effects except one set of contacts had a high contact resistance which was

quickly corrected by the application of a low dc voltage stress across the

contacts.

4.1.1.5 Applicability of Switch Data to Other Components

This section describes the expected failure modes of switches and what

other components would be expected to experience similar failure modes.

15
2.6

J-%

2.6

a' 2.4

2.2

0

Time (seconds)

Fig. 7 Load Current to Switch in Test 4
2.8 -

4-V

C

I.-&

2.21-

I i I i p I a a p p I ~ ~ * * I a . a s I a a I t I a a

10006 3000 400 5000

Time (seconds)

Fig. 8 Load Current to Switch in Test 5
Where the switches did not experience a particular failure mode, the other

components would generally also not be expected to experience that failure

mode under similar conditions, and conversely.

The general failure modes expected for switches are failure to carry a

load or leakage currents/shorts between terminals or to ground. The

monitored switches gave continuous data for load current and leakage

current. The unpowered switches give data for before and after contact

resistances and insulation resistances. Based on calculations of

condensation temperatures for a hydrogen chloride, water, and air system,

together with an indication of the amount of hydrogen chloride generated

by burning PVC [13], the potential for hydrogen chloride condensation on

cool components appeared significant. Consequently, many of the switches

were left unpowered because hydrogen chloride condensing on the switches

could lead to rapid corrosion or high leakage currents when the switch was

later powered up. The switches that were powered were intended primarily

to monitor leakage currents on the premise that particulates and hydrogen

chloride might cause conductive media on the switches, leading to

immediate leakage currents.

Components not tested which might experience similar failure modes

include motor control centers (MCCs), switchgear (SG), terminal blocks,

and temperature, pressure, and limit switches. All of these components

have contacts and connections which are generically similar to those found

on switches. The switch data should effectively cover all terminal block

failure possibilities under the same conditions. However, the remaining

equipment may have additional failure modes not addressed by switch data

alone. For example, failure modes of a motor controller failing to engage

could be unrelated to any switch failure modes.

4.1.2 Relays

4.1.2.1 General

In general, the relays appeared similar to the switches described in

section 4.1.1.1. All of the relays tested were originally protected by

some type of cover, but some of these covers were removed to allow more

environmental penetration and simulate other relays which are of open

construction. The powered and monitored relay in test 4 exhibited the

same type of particulate polarization that was experienced by the switch

in test 4. The relays in test 5 showed very little evidence of

particulate deposition, similar to the switches in test 5.

4.1.2.2 Unpowered Relays

Only one relay was left completely unpowered in the tests (test 4).

This relay was located in the corner cabinet toward the bottom (about one

foot from the floor) and the cover of the relay was left off to expose the

inside of the relay as much as possible. The only evidence of any

degradation resulting from the fire was light corrosion on the metal parts

of the relay. The corrosion was insufficient to cause any malfunctioning

of the relay.

It was noted that the Agastat relays tested can be vulnerable to high

18
contact resistance at low test voltage levels, both before and after

exposure to the fire environments.

4.1.2.3 Powered Relays

In each of tests 4 and 5 one relay was powered, loaded, operated, and

monitored and another relay was operated and only the coil current was

monitored. In both cases, the powered and monitored relay was an Agastat

GPI relay located about 4 feet off the floor at sector I (see Fig. 2). In

test 4, the cover was left on the relay and in test 5, the cover was

removed. In test 4, the second relay which was operated was a General

Electric model 12HFAl5lA9F. In test 5, the second relay which was

operated was an Agastat model GPI relay. Both of these relays were

located in the bottom of the corner cabinet about 1 foot from the floor

(see Fig. 2). The relays in test 5 appeared almost as new after the test

as did the General Electric relay in test 4. The Agastat relay in test 4

had no evidence of damage other than the polarized particulate described

above. The particulate was insufficient to affect relay operation or

create measurable leakage currents.

Plots of the temperature environment outside the relay and inside the

relay near the contacts from test 4 are shown in Fig. 9. These plots give

an idea of the amount of thermal lag caused by the cover being on the

relay. The current flowing to the load on the relay contacts is shown in

Fig. 10. The relay was operated in both directions every minute,

accounting for the drop to zero load current every minute. The two

sections of lost load current shown on the plot were the result of a

sticking relay on the datalogging system and are not failures of the test

relay. (The datalogger relay was found with severely pitted contacts and

was verified to be sticking after the test.) A similar plot for the relay

in test 5 is shown in Fig. 11. The relay in test 5 was operated every 5

minutes. Neither plot showed any indication of failure of the relay to

pick up and carry its load. In neither test did the leakage currents

measured to the normally-closed contact (open when the relay was

energized) ever exceeded the detection threshold of the ac current sensors

used (0.25 mA). The coil currents showed expected behaviors and are not

shown. The values of coil current when energized were nominally 50 mA for

the Agastat GPI relays and 210 mA for the General Electric HFA series

relay.

4.1.2.4 Humidity Exposure of One Relay

The relay which was powered and monitored during test 4 was put into

the humidity chamber (at 27 0 C and 70% relative humidity) with its cover

intact along with the switches described in Section 4.1.1.4. No adverse

effects were noted on the relay after the 12-day exposure.

4.1.2.5 Relays Tested to Thermal Failure

4.1.2.5.1 Agastat GPI Relays

Two Agastat relays were tested to thermal failure in an environmental

test chamber. The two relays use an external socket for termination. Two

different socket configurations are available and one relay was tested

with each type of socket.

19
Outs i do Ins i do

U 50

td- -

CD ---

CL . -- - --

E 20

Time (seconds)

Fig. 9 Air Temperature Inside and Outside of Relay in Test 4
2.8

2.6

CC

o 2.4

L

3

2.2

1000 2000 3000

Time (seconds)

4000 5000

Fig. 10 Load Current to Relay in Test 4
2.6

S2.4

IL5

Time (seconds)

4000 50B0

Fig. 11 Load Current to Relay in Test 5
A problem occurred in the computer program for the test chamber

temperature control which caused two unplanned temperature excursions in

the early part of the first test. The temperatures reached caused surface

melting of the relay cover but no apparent internal damage occurred

because of the short duration of the temperature excursions. The ultimate

failure temperature of the relays was much higher than the temperature

excursions, indicating that there was probably no significant damage from

the temperature excursions. After the program was corrected, the test was

successfully completed as described below.

The temperature profile for the first relay is shown in Fig. 12. The

coil temperature is higher than the chamber temperature because of

self-heating effects. Fig. 13 shows the leakage current for contact #2 as

a function of time, Fig. 14 shows the coil current as a function of time,

and Fig. 15 shows the motor starter current as a function of time. These

plots (Figs. 13,14,15) show that at approximately 155 minutes into the

test, the contact #2 leakage current went from 0 to 0.84 amps (maximum

value limited by the 120 ohm resistor), the motor starter current went to

0, and the coil current jumped to about 0.94 amps from an initial value of

about 0.03 amps. Operation of the motor starter became erratic and the

test was terminated. It should be noted that the location of the sensor

measuring motor starter current really measures the current supplied to

the contact #2 common connection.

In addition to the above plots, data was taken for contact

resistances, pickup voltages, and dropout voltages. With the exception of

two points, contact resistances were all below 50 milliohms. The two

extreme values were 150 and 250 milliohms. Pickup voltage ranged from 53

to 63 Vac with pickup voltage generally increasing with temperature.

Dropout voltage ranged from about 21 to 24 Vac.

Post test analysis of the relay indicated several apparent failures.

First, a short had occurred between one of the coil power leads and the

normally closed terminal of contact #1. The two power leads to the coil

were not specifically identified during the test since ac power was being

used. Consequently, it is not known whether the short occurred to the hot

side of the coil power or the neutral side. A slight decrease in the

contact #1 current and a slight increase in the coil current which could

not otherwise be explained were observed, indicating the short was

probably to the hot side of the coil. However, the amount of the current

changes indicates only a partial short (on the order of 100 ohms). The

short found after the test was a more complete short which could have been

caused by the fairly rapid cooldown after the test was over. The short

was between two adjacent wires used for connections in the socket. A

photograph of the failure area is shown in Fig. 16.

The second failure mode observed was apparently caused by the rapid

cooldown after the test. An open circuit was indicated between the two

coil terminals and between several of the terminals which should have been

connected when the relay was in the deenergized position. Post test

examination revealed severe socket warpage which apparently caused a loss

of some connections between the socket and the relay.

The failures discussed thus far cannot account for the primary failure

which resulted in the test being terminated. The cause of the primary

23
'Chamber --- ~- CailI

250

U •,

a)

4.)

r_ 18 --. ' L

I---

0 20 40 6s 8s 100 120 140 160

Time (minutes)

Fig. 12 Coil and Chamber Temperatures for First Thermal Failure Test
1.2

1

.8

a:

.4

.2

0 1, t I I, I tI I I,

0 20 40 60 80 100 120 140 160

Time (minutes)

Fig. 13 Contact #2 Leakage Current for First Thermal Failure Test
1.2

I

IL

I .8

.Ga

0'

C

0

L

L

U

.4

01p * g i I a a a I . a a I a a a I t a a I a a a I I * a a a a

140 so 80 120 140 ISO

Time (minutes)

Fig. 14 Coil Current for First Thermal Failure Test
.4

.3

.2

4-)

00

U

o I I * I I a I a a a I I i I I I I I I I

0 20 40 6s 80 100 120 140 160

Time (minutes)

Fig. 15 Motor Starter Current for First Thermal Failure Test
* -

w,-• i I

Fig. 16 Shorted Wires in the Socket Ifrom the First Thermal Failure Test

failure had to bela short between the-,hot side of the relay coil and the

normally closed terminal of contact #2. No such failure could be found in

examining the reliay after the test. However, the base of the relay w~s so

severely arped',that apparently two or more of the terminal screws onýthe

socket came into contact with the metal baseplate and shorted together.

This was partially confirmed by checking continuity of different terminals

when the socket was held onto a metallplate; several definite

possibilities of shorting terminals were found.

During the test of the second relay, a fuse blew at 99 minutes into

the test. The cause of the-blown fuse was traced to a relay in the

datalogging system having fused contacts. The fuse and datalogger relay

were replaced and since the test relay still seemed to be operating

normally, the test was continued. The temperature profiles for the test

and the coil temperature are shown in'Fig. 17.

A plot of the-motor starter current (actually current supplied toi

common terminal-.of..contact.#2)'isshown.in.Fig., 18 ,.the..contact .#1 'load

current is shown ^in Fig. 19, the coil current is shown in Fig. 20, and the

contact #2 leakage current is'shown in Fig: 21. About 30 minutes into the

second part of the test, the current supply to contact #2 and the contact

#2 leakage current both increased by approximately the same amount,

indicating a dead short connecting the-common and normally closed (open at

the time) terminals of contact #2. 7The test was continued until between

75 and 80 minutes, the load current was lost twice and the the test was

terminated.

Post test analysis of the relay indicated some failure modes similar

to the first relay. Immediately after the test, several contacts which

28
Chamber- - -- -Coil

200

U

150

S150

v

L

3

L

4)

180

Time (minutes)

(a) Prior to Fuse Failure

Chamber- --- Col I

258

U

IM 200

1513

IV

L

:3 108

4.)

a) 50

Of.

so so

Time (minutes)

(b) After Fuse Replacement

Fig. 17 Coil and Chamber Temperature for Second Thermal Failure Test

29
I

U

.6

.6

.4

.2

40 so

Time (minutes)

100

(a) Prior to Fuse Failure

I

0:

4.f

L

L

U

.B

.6

.4

.2

20 40 60 so

Time (minutes)

(b) After Fuse Replacement

Fig. 18 Motor Starter Current for Second Thermal Failure Test

30
2.5

2 .4•

C:

U

2.3

2.2

2.1

0 20 40 so

Time (minutes)

(a) Prior to Fuse Failure

Be

3

2. n.-. I~

a:

C

a,

L

L

U

2

1.5

1

I --

95 E-- .I I S I I I . I I I I . I I ,

0

!

} Be

Time (minutes)

(b) After Fuse Replacement

Fig. 19 Contact #1 Load Current for Second Thermal Failure Test

31
.2

a:

U

* 15

.1

.05

40 60

Time (minutes)

(a) Prior to Fuse Replacement

01%

T-

%-0

+3

a151ý-

.1

.05

o 20 40 60 80

Time (minutes)

(b) After Fuse Replacement

Fig. 20 Coil Current for Second Thermal Failure Test

32
.01

a

L

L

:3

I " L .1-1 k -1 - - .-- -. AL ... I.

40 so so

Time (minutes)

(a) Prior to Fuse Failure

.6

.6

L

L

U

'ft

Ii

.4

.2

Time (minutes)

(b) After Fuse Replacement

Fig. 21 Contact #2 Leakage Current for Second Thermal Failure Test

33
should have been connected indicated open on an ohmmeter and all of the

contact #3 terminals were effectively shorted together. This short was

later found to be in the socket. Insulation resistance measurements on

the socket produced what appeared to be breakdown at some dc voltage

levels (different locations appeared shorted at all test voltages

including the low voltage of a hand-held meter and all voltages of the

insulation resistance tester: 50, 500, and 1000 Vdc). However, the

apparent breakdown would come and go at different voltage levels and

sometimes even at the same voltage level after applications of other

voltages. Shorting of terminal screws to the baseplate was not observed

in the second test because of the different socket design. However, a new

failure mode was observed. The contact support of contact #1 (the contact

carrying the nominal 3 A load current) had become hot enough to melt as

shown in Fig. 22. The melted support was the cause of the loss of load

current observed at 75 to 80 minutes into the second part of the test.

Because of the melted support, the coil would no longer energize after the

test although it did draw rated current at rated voltage.

At some times during the test, high contact resistances were noted

with the voltage applied by the measurement circuits. In each case, the

test was continued because the relay was carrying its load and no leakage

currents were observed.

In addition to the data discussed above, insulation resistance

measurements, contact force measurements, and pickup and dropout times

were measured before and after the tests where possible. In all cases,

except those noted above, no degradation was evident in the measured

properties.

Fig. 22 Melted Contact Support from Second Thermal Failure Test

34
4.1.2.5.2 General Electric HMA Relay

One General Electric relay was tested in the environmental chamber.

The relay was a model 12HMAlllB9. Two profiles were run as shown in Fig.

23. The second profile was run because failure of the relay was not

observed up to the first programmed maximum temperature of 270 0 C and the

objective of the test was to continue until the relay failed. As can be

seen from Fig. 23, the second profile was started when the chamber

temperature was slightly above 2000 C shortly after completion of the

first profile. The coil current is shown in Fig. 24 and the load current

is shown in Fig. 25. Leakage current is not shown since it never exceeded

the ac current sensor detection limit of 0.25 mA. At about 92 minutes

into the second test, the load current was lost and the coil current

jumped significantly. The test was discontinued and when the chamber was

opened, the lead wires to the relay were burning. After extinguishing

with carbon dioxide and cooldown of the chamber, the relay was removed.

The fire and extinguishment caused significant damage to the relay, as

shown in Fig. 26. The fire was caused by the two coil lead wires shorting

together and fusing as shown in Fig. 27. The fire apparently started at

about 98 minutes, about 2 minutes after the load current was lost. The

cause of the loss of load current could not be determined because of the

fire damage.

Similar to the Agastat relays, the GE relay also had high contact

resistance readings in some cases. The high readings occurred primarily

when the relay was deenergized (and hence the contact forces were lower).

As in other cases, the test was always continued since the relay continued

to carry its load without measurable leakage currents. The relay was too

severely damaged to make any post test measurements.

The coil operability indication was lost several times during the

test, apparently resulting from high contact resistance on the relay at

the voltage level used for the indication (12 Vdc). Again, the test was

continued each time because the more important criteria of carrying the

load and preventing significant leakage currents were normal.

4.1.2.6 Applicability of Relay Data to Other Components

This section describes the expected failure modes of relays and what

other components would be expected to experience similar failure modes.

Where the relays did not experience a particular failure mode, the other

components would generally also not be expected to experience that failure

mode under similar conditions, and conversely.

The general failure modes of relays are similar to those of switches

and the data on relays and switches support each other. One additional

general failure mode of relays is failures associated with the coil

preventing the relay from operating. Normally, failure of the coil (as

might be expected from high temperatures) would be expected to result in

deenergizing the relay to what is normally the "safe" position, although

other coil failure modes are possible.

Components not tested which might experience similar failure modes are

the same as for switches. The relay data supports the switch data and

adds to it by also considering the remote actuation function using a

35
Chamber- - - -Coil

0)

L

L

0~

2L

E300

250

200

150

100

50

Time (minutes)

(a) First Profile

Crr- -Coil

5o

M

(D 400•-

0,

300-~

4 -)

2820

o- 20=0i i i i I P~ r~ a ~

Time (minutes)

(b) Second Profile

Fig. 23 Coil and Chamber Temperatures for Third Thermal Failure Test

36
a:

L

L

.21

.15

.1I

00 100 ISO 200

Time (minutes)

(a) First Profile

+J

C

0

L

L

U

1.5

I_-

.5

| I I i J a I I I I ." I I I

20 40 80 100

Time (minutes)

(b) Second Profile

Fig. 24 Coil Current for Third Thermal Failure Test

37
3

2.5

11%

CC

L

L

U

2

1.5

1

.5

0 I t I I I t I I

50 100 15I

Time (minutes)

(a) First Profile

3

2.5

q: 2

I 5

.A A

Ii

.5

20 40 80 100

Time (minutes)

(b) Second Profile

Fig. 25 Load Current for Third Thermal Failure Test

38
Fig. 26 Post-test Photograph of HMA Relay After Fire Occurred

Fig. 27 Coil Wires Shorted Together to Cause Fire

39
coil. This additional failure mode would be primarily applicable to 4CCs

and SG in addition to the relays. The primary differences between the

switches/relays and the MCCs/SG are: 1) MCCs and SG are much larger, 2)

MCCs and SG typically operate at higher voltages and currents, and 3) many

MCCs and SG may be operated either automatically or manually while the

switches tested are manual only and the relays tested are automatic only.

Of these three general differences, the only one likely to cause failures

not related to relays or switches tested would be the higher operating

voltages. Failures resulting from breakdown at the higher voltages might

not be expected because the larger size of MCCs and SG increases the

distances over which breakdown must occur. However, high voltage

breakdown failures cannot be dismissed based only on the switch/relay

data.

4.1.3 Meters

4.1.3.1 General

A total of 13 meters were tested in various tests. None of the meters

were powered during the test but calibration checks were performed before

and after the tests to establish functionality. None of the meters showed

any indication of operability problems except two (not included below or

as part of the 13 tested) which were put in or directly above the burning

cabinet and were destroyed by heat. The meters were all General Electric

Type 180, 185, or 195. The meter locations (see Fig. 1 for tests 1-2 and

Fig. 2 for tests 4-5) were as follows: test 1--above burn cabinet (this

one continued to work even though it was directly above the burning

cabinet); 2' out from burn cabinet, 5' high ; in single bay cabinet about

8' away; and 8' from fire, 10' high; test 2--one in single bay cabinet

and two in adjacent cabinet; test 4--two panel mounted in corner cabinet

and one at sector 1, 4' high; test 5--two panel mounted in corner

cabinet.

4.1.3.2 Applicability of Meter Data to Other Components

This section describes the expected failure modes of meters and what

other components would be expected to experience similar failure modes.

Where the meters did not experience a particular failure mode, the other

components would generally also not be expected to experience that failure

mode under similar conditions, and conversely.

General failure modes possible for meters include leakage currents

(shorting) between the terminals, open circuits (not considered likely),

warping/melting of the meter case (usually plastic) leading to binding of

the indicator, and particulate or corrosive vapors penetrating into the

meter and jamming it. The problem of leakage current between the

terminals is addressed by the switch and relay data given previously where

leakage currents were found to be negligible in the tests conducted.

The only components not tested which may experience failure modes

associated with binding or jamming indicators would be the indication

portion of indicators/controllers and mechanical gauges. It should be

noted that the types of meters tested are all reasonably well sealed from

the outside environment. No evidence of particulate or corrosive vapor

penetration into the meters was noted in any case except for the destroyed

40
meters. Any type of meter or gauge which is not reasonably sealed could

behave considerably different (see discussion of strip chart recorder

failures). It should be emphasizes that failures from direct fire damage,

such as meters becoming short circuits, were not addressed by this effort.

4.1.4 Chart Recorder

4.1.4.1 General

Two strip chart recorders, Bailey Controls Series 77, were tested.

The first was tested in test 3 and was located about 8' from the burning

cabinet near the burn room door and about 5' from the floor (see Fig. 1).

The covers were removed from the recorder and it was not powered. The

temperature profile that the recorder was exposed to is shown in Fig. 28.

As a result of the fire environment, the strip chart recorder failed to

function. The failure mode was particulate buildup on the pen sliders

with the pens unable to move in either direction. After an attempt at

cleaning with a solvent, the pens would still not move. The rest of the

recorder, including the electronics and motor drives seemed to work

properly. A photograph of the failed slider is shown in Fig. 29.

Because the intentional removal of the covers of the recorder may have

allowed the failure, a second recorder was tested in test 4 and was panel

mounted in an open-backed cabinet with all covers intact. After the test,

light crud buildup was noted on the sliders, significantly less than in

test 3. Two of the three pens worked correctly. The third pen would work

correctly up to about 75% of its full scale. However, it would not

deflect any farther. The recorder was checked using a slowly changing

voltage as would be expected in a power plant application. After failing

to deflect fully, the voltage was rapidly changed from a low value to a

full scale value and the crud deposits were easily removed, allowing the

recorder to work normally thereafter.

4.1.4.2 Applicability of Chart Recorder Data to Other Components

This section describes the expected failure modes of chart recorders

and what other components would be expected to experience similar failure

modes. Where the recorders did not experience a particular failure mode,

the other components would generally also not be expected to experience

that failure mode under similar conditions, and conversely.

The general failure modes expected for strip chart recorders are

corrosion or particulate buildup between moving parts (failure mode

actually observed), thermal failure or degradation of electronic

components, or low level leakage currents on the circuit boards leading to

loss of correct recorder operation.

Components not tested which might experience similar failure modes

include any type of meter, gauge, automatic switch (e. g. temperature), or

small motor which is not sufficiently protected from the environment

(mechanical binding problems) and many types of components which contain

printed circuit boards and may be vulnerable to electronic component

failure or degradation or leakage currents on the circuit board. Examples

of the latter include logic equipment, controllers (some types), power

supplies, solid state relays, and transmitters.

41
100

00-

a) "0 -

I..

a.. 46

Em

I £ i .I I i i 1" l I I £ I l I I

0 .10 20 36

Time (minutes)

50

Fig. 28 Temperature Near Strip Chart Recorder in Test 3
Fig 29 Fa~h~Slider'-6 fehais Etrip Chart -Recorder' '

Fi 2§Fale C e

4.1.5 ';Electronic Cunter ~~* 0 16 L'1A

4.1..1 General '* . . .

-r iý r, h -J

Two7'eliectr-onic' Cýouter's 'we.re- tested Both-wereJHewlett Packard model

ý' `ý - .. 1i I; J "

5300B measuri ' eso' 'c' p e'd 302A5 ~ uniy'ersaic utnt~ers~ h

ng ~ ~ u-1-O ~ ~ . ,y''ems h

firstswa -t"te&'din 1-te~st 3 liid';as`, l~cated-a bout'6~r ~ni rh 

cabinet anid1 about 8' fro'm the rfloor'.-- The"-clo-Versý:ere `'e-'m"6oved-(osm~t

the p~ossii it'y o-f alectSironIc erMcuitsmbo"as notrbeinp h nar sed) rand' hbcounter-was not Tonihner 'ounterwa reo d"

I .I.;`A,5.1I:

and measuring s fes cbou to at aoute.167 •T

first teste'd'ine was .test3 an slo a ned'peaked 6'afomth aburig .

Significant deposits of particulate wereý foun'd on he circuit boards' after,

the 'test.as" shown' in' Fig. 30, but' theg counter'1 til l functioned perfectly. '

Bec-ause of thie "ohumidityd on. the day of th etest-'and because'no water

suppressionVwas usied in 'the room'the counter was 'subsequently put in a

humidity chamber to evaluate the effects of high humidity.. The first.

exposure was 'at,"32 C t(900F)',"a- 9dabaoiuti.5,5 hours with ,'•

the counterpoered-o ill effcts were :noted and the huimidity was - -raised ft'o '95%lwithr'the'Eounter still pord rfer7.5 hours at95%'',

humidiey ',front1⁄2panel indication had been- lost and the fuse was, found blown. "Th exact -time'when the fuse- blew was' not on some time

during the of' the fus'with"a' crrectlyjrated - -. fuse,-'even rafter "dryingof thcounter, resultingin ,the u

Ho'we'ver,5' replacementwiih 'w high' eenough-'rated' fus~e-w6ould allow the counter

to work for' a sho'£t" :eriod b'ef0'te ' rea ings woulddgo lrratic"an-d the. ."

power supply rectifier'diodeZsewoul'd get ery'hot'i Before-a-posftive 3f

diagnosis 6f :thei'obleco"•iu•-dbef 'tound,"itheS counterr began workin ,...

43
Fig. 30 One Location of Leakage Currents on Counter Circuit Boards

normally again. The counter was returned to the humidity chamber to see

if the 9roblem would return. The counter was powered and the conditions

were 40 C (104 0 F), 95% relative humidity for 18 hours. The counter

was found failed as before, again not knowing the exact time of failure.

The problem was eventually traced to what appeared to be a transistor

failure in the power supply. Based on examination of the counter

schematics, failure of the transistor, manifested as high base-emitter

leakage current, could cause the noted failure. Replacement of the

transistor returned the power supply to normal, but curve traces of the

original transistor did not show any problems. Subsequently, the original

transistor was reinstalled and worked correctly. The only conclusion is

therefore that a conductive media (probably corrosion related) had formed

in the vicinity of the transistor and had allowed leakage currents. The

transistor replacement must have removed enough of the conductive media to

reduce the leakage current and allow the circuit to work properly.

Following the diagnosis above, the counter appeared to work

perfectly. About an hour later, the counter was rechecked and found to be

malfunctioning from a problem different than the power supply problem.

The power supply outputs were verified by checking the various output

waveforms. The problem was eventually traced to 4 parallel data lines

which had improper values. Further, the values indicated were

contaminated with a significant amount of noise. The 4 lines run adjacent

to each other across the circuit board. Selective brushing of the circuit

board first improved and then completely restored the output. The

brushing was largely along the adjacent paths of the data lines. The

incorrect output was probably caused by leakages among these data lines

and possibly with other nearby lines resulting from the corrosive effects

44
of the particulate in a high humidity environment. A photograph of the

area of the data lines is shown in Fig. 30.

The second counter was tested in test 4 and the top cover was

removed. The counter was located in the bottom of the corner cabinet and

was exposed to the temperatures shown in Fig. 31. The result of the

exposure was a limited amount of particulate deposited on the circuit

board, almost none when compared to the counter in test 3. No loss of

function occurred as a result of the test.

4.1.5.2 Applicability of Counter Data to Other Components

This section describes the expected failure modes of counters and what

other components would be expected to experience similar failure modes.

Where the counters did not experience a particular failure mode, the other

components would generally also not be expected to experience that failure

mode under similar conditions, and conversely.

The general failure modes of the counters are similar to those for

strip chart recorders with the exception of mechanical binding

possibilities for the recorder. The reason for including the counters in

the tests was to represent electronic circuits which are digital as

opposed to the analog recorders and other analog equipment discussed

later.

Components not tested which might experience similar failure modes

include those with electronic circuits such as logic equipment,

controllers (some types), power supplies, solid state relays, and

transmitters.

4.1.6 Other Electronic Equipment

4.1.6.1 General

The remaining equipment was all tested in test 2. The equipment

consisted of a Raytheon model QRD60-5 power supply, a Hewlett Packard

model 467A power amplifier, and a Tektronix model 133 plug-in unit power

supply with a type 1A4 4-channel amplifier plug in module. The power

supply was located about 2' above the burning cabinet, the power amplifier

was located in the adjacent cabinet near the wall away from the fire about

6' high, and the power supply/amplifier was located about 6' directly out

from the fire and about 4' high. The burning cabinet had an open door,

exposing the power supply/amplifier to the direct radiation effects of the

fire. The Raytheon power supply was later tested in both tests 4 and 5

where it was located in the bottom of the corner cabinet about 1' from the

floor.

The power supply no load output voltage was monitored throughout all

three tests and did not vary by more than 1.5% in test 2 and 0.05% in

tests 4 and 5. The temperature profile from test 2 is shown in Fig. 32.

The peak temperatures in tests 4 and 5 were about 400 C and 250 C,

respectively. Tests 4 and 5 were intended primarily to see if any

corrosive vapors might condense on the power supply in the cooler regions

low in the room. No evidence of any damage to the power supply was found

during or after any of the tests.

45
40

35

U

0D

L

E

25

o'

15

a 2000 3000 4000

Time (seconds)

Fig. 31 Temperature Near Counter in Test 4
150

01

U

0r)

100

E° CL 50 - ~~0

101

Time (minutes)

40 58

Fig. 32 Temperature Near Power Supply in Test 2
The power amplifier was powered with an input voltage of nominally 1 V

and its output was monitored after amplification by 5. The average of the

temperatures about 2D above and below the amplifier is shown in Fig. 33.

The temperature profile at the amplifier would be close to this average.

The amplifier output matched the input (multiplied by five) with an

accuracy of better than 0.5% throughout the test. Post-test measurements

soon after the test and after several days verified correct operation of

the amplifier in both dc and ac applications.

The 4-channel amplifier and power supply was powered with the same

nominal 1 V input as the power amplifier. The temperature profile near

the 4-channel amplifier is shown in Fig. 34. One channel of the amplifier

was set for an amplification of 5 and the output was monitored. As the

test progressed, the output signal error increased to about 20% and then

was lost. After the test ended, the output returned for about 6 minutes

with an initial error of less than 1% but increasing with time to about

16% after which the signal was again lost. After the test, the amplifier

power light was found on and the cooling fan was running but no output was

being produced. Post-test measurements soon after the test and several

days later indicated the amplifier was working on both dc and ac with

minimal error. Examination of the plug in unit power supply schematic led

to the discovery of a thermal cutout switch which cuts the power off to

everything except the on indicator and the cooling fan when the

temperature exceeds 580C (137 0 F). Fig. 34 shows that the temperature

in the vicinity of the amplifier did exceed 58 0 C, resulting in the

cutoff. No instances of similar thermal cutoffs being used in nuclear

power plant components are known.

Because the amplifier returned to normal following return to room

temperature, the output error was almost certainly a result of thermal

drift of subcomponents in the amplifier or power supply. It should also

be noted that the cabinet door was open, exposing the amplifier to the

direct effects of flame radiation. The thermal cutoff worked as designed

to shut the unit down until the temperature returned to normal.

4.1.6.2 Applicability of Data to Other Components

This section describes the expected failure modes of electronic

equipment tested and what other components would be expected to experience

similar failure modes. Where the electronic equipment did not experience

a particular failure mode, the other components would generally also not

be expected to experience that failure mode under similar conditions, and

conversely.

The power supply, power amplifier, and 4-channel amplifier would be

expected to have failure modes similar to the electronics of the strip

chart recorders and the counters. These components are in no specific way

related to actual components used in nuclear power plants. They were

chosen only to reflect the type of subcomponents and potential failure

modes that might be related to power plant components. They were all well

used prior to testing and were a number of years old, similar to some

types of equipment currently found in power plants.

Components not tested which might experience similar failure modes are

the same as discussed previously for the recorders and counters. The

48
U

0(

"0

L

a

CL 40

E0

0 10 20 30 40 50 6s

Time (minutes)

Fig. 33 Average Temperature Near Power Amplifier in Test 2
120

100

Co

L

00

a0 10 20 30 48 5o 6O

Time (minutes)

Fig. 34 Temperature Near Oscilloscope 4-channel Amplifier in Test 2
testing of these components was primarily to support the recorder and

counter data for olber equipment and equipment of more different

manufacturers.

4.2 Summary 2f Component Data ADplicability to Other Components

Table 5 summarizes the top ranked components described in section 2.0,

some of their potential failure modes, and components tested which might

be expected to have similar failure modes. This table demonstrates that

although all of the highly ranked components from Section 2.0 were not

explicitly tested, other components which were tested have generically

similar failure modes which represent many of the failure modes of

untested components.

In addition to the listed failure modes, all components would

eventually fail if subjected to high enough temperatures. The testing of

relays to high temperatures in the test chamber and the temperatures

recorded during the cabinet tests give the impression of a large amount of

temperature margin for components generically similar to relays, such as

switches, MCCs and SG. The high temperature that the counter was exposed

to during test 2 also indicates a reasonably high temperature margin for

electronic equipment exposed to the relatively short high temperature

environment of the cabinet tests. However, the 4-channel amplifier had

output errors as high as 20% prior to the thermal cutout operating,

indicating the possibility of large temporary errors from electronic

components exposed to high temperatures. It should be repeated that the

amplifier was located such that it received direct flame radiation effects

from the fire. Because no components other than electronics reached

temperatures anywhere near their expected damage thresholds based on the

tests discussed, most thermal failure modes are not included in Table 5.

For example, high temperature failures of MCC or relay coils are not

included except for leakage currents/shorts. However, because of the

potential temperature sensitivity of some electronics, they are still

included in the table.

The primary failure modes (after temperature effects have been

considered) are primarily a result of potential corrosive action,

particulate deposition, and/or humidity effects. The major expected

failure modes include leakage currents/shorts and mechanical binding of

moving parts. In some cases, leakage currents may appear to be

electronics failures as was noted for the counter from test 3 which was

exposed in the humidity chamber. One additional failure mode possibility

is the loss of continuity between electrical contacts.

The major failure mode actually observed was the failure of the two

strip chart recorders (primarily the one in test 3 when the covers were

removed). A second failure observed was a result of leakage currents on

the circuit boards of the counter from test 3 after significant exposure

to a humidity environment. A third potential failure was the error (as

high as 20%) experienced by the 4-channel amplifier in test 2 prior to its

thermal cutout operating. The remaining "failures" were specific cases of

high contact resistance on relays and switches at the voltage potential

used for testing. In no case was the increased contact resistance high

enough to prevent correct operation when a small voltage (up to 15 V

maximum) was applied across the contacts. The smaller relays with

51
Table 5_ Sum~ go Co ionent, Failup.s Modes

Com~onent Ranked i

Recorders Particulate Buildup

Leading to Binding

Electronics Failures

Corrosion of moving parts

Low Level Leakage Currents

Motor Failure

Components TesteKith Similar

Expecte failure Modes ft

Configuration Tested

Recorders *

Recorders, Counters, Amplifiers *,

and Power Supply

Recorders

Counters *, Amplifiers, and

Power Supply

Recorders

Logic Electronics Failures Same as for Recorders

Equipment Low Level Leakage Currents Same as for Recorders

Controllers Electronics Failures Same as for Recorders

Leakage Currents/Shorts Switches and Relays

Low Level Leakage Currents Same as for Recorders

High Resistance Contacts Switches *, Relays *

Power Electronics Failures Same as for Recorders

Supplies Leakage Currents/Shorts Same as for Controllers

Low Level Leakage Currents Same as for Recorders

Meters Particulate Buildup

Leading to Binding

non-sealed meters Recorders *

sealed meters Meters

Corrosion of Moving Parts

non-sealed meters Recorders *

sealed meters Meters

Leakage Currents/Shorts Same as for Recorders

Solid State Electronics Failures Same as for Recorders

Relays Low Level Leakage Currents Same as for Recorders

ElectroMechanical

Relays

Leakage Currents/Shorts

High Resistance Contacts

Same as for Controllers

Same as for Controllers

52
Table 5- $.MMAY Of Component Failure Modes (cont.)

Transmitter Leakage Currents/Shorts

Low Level Leakage Currents

Electronics Failures

Same

Same

Same

as

as

as

for Controllers

for Recorders

for Recorders

Switches Leakage Currents/Shorts Same as for Controllers

High Resistance Contacts Relays *, Switches *

Battery Leakage Currents/Shorts Same as for Controllers

Chargers/

Inverters

MCCs/SG Leakage Currents/Shorts Same as for Controllers

High Voltage Breakdown None

Batteries Leakage Currents/Shorts Same as for Controllers

Temperature

Switches

Leakage Currents/Shorts Same as for Controllers

* These tested components had

the stated failure mode.

actual instances or some indication of

53
enclosed contacts did not experience any high contact resistances. As

noted previously, some of the Agastat relays had high contact resistances

prior to the test with the voltages used for testing.

Most of the major failure modes for components were not observed in

the cabinet tests, with the exceptions noted above. The major failure

mode not addressed in the cabinet tests is high voltage breakdown of

electrical equipment, most notably MCCs and SG. Failures resulting from

particulate (including corrosive effects) and humidity interactions were

addressed to some extent by the components put in the humidity chamber.

The counter survived over 5 hours at 90% RH followed by an unknown amount

of time at 95% RH. The components tested for almost two weeks at 70% RH

all survived without any ill effects.

4.3 Chloride n~ Measurements

Chloride ion measurements were made in tests 3, 4, and 5. The

intention of the measurements was to establish the chloride ion

concentration in the exhaust as a function of time with the hope of

relating this value to a chloride ion generation rate and possible

corrosion of components. The chloride ion concentrations obtained in test

3 were compared with estimated theoretical values and other experimental

work summarized in Ref. [131 and found to be lower by nearly two orders of

magnitude. The system was redesigned as explained in Appendix A to

eliminate the possibility that a large portion of the sample was lost in

the sampling system in test 3. The results of tests 4 and 5 were similar

in amount collected to test 3 and were in fact both lower (on a normalized

basis) than test 3, indicating that the sample was probably not being lost

in the sampling system and the chloride ions were being measured

accurately. Because particulate matter can react with vapors in the air

(such as reactive hydrogen chloride) and because most of the particulate

was effectively filtered out of the sampling system prior to the bubbler

(active filtering in test 3; deposited on the sample line or never

getting into the sample line which was perpendicular to the flow direction

in tests 4 and 5), a particulate sample was taken after test 4 for

chloride ion analysis. The particulate sample was taken from the floor of

the burn room. The room had been swept prior to the test so contamination

of the particulate was kept to a reasonably low level. Another sample for

chloride ion analysis was taken from the cable residue to see how much

remained after the cable was burned.

4.3.1 Chloride Ion Analysis of the Particulate and Residue Samples

Chloride ion analysis was performed by mercuric nitrate titration on

the two samples. The particulate sample contained 33% water soluble

chlorides by weight and the residue sample contained 0.7% water soluble

chlorides by weight. Other investigators using small-scale apparatus [131

have reported large quantities of hydrogen chloride evolved by heated or

burning polyvinyl chloride. Taking the previous small scale results

together with the current larger-scale results indicates that a large

quantity of hydrogen chloride was probably generated by the cabinet fires,

but most of it was deposited on particulate prior to leaving the burn

room. These results are consistent in that a significant amount of time

is available in larger scale tests for particulate/HCl reactions while in

smaller scale tests, less time exists for the reactions. Another possible

54
explanation for the difference noted is that all of the exhaust products,

including the particulate, may have been collected in the small scale

experiments, resulting in no distinction between vapor phase hydrogen

chloride or hydrogen chloride reacted with particulate. Chloride ion

analysis after the Brown's Ferry fire [31 found between 14 and 19%

chlorides in several soot samples from the first and third floors of Unit

1, further indicating that the HCl and particulate combine in larger-scale

fires.

The major implications of HCl combining with soot are 1) particulate

generated from burning PVC and deposited on components will likely contain

a large quantity of chloride ions and 2) hydrogen chloride vapor in the

air in condensing concentrations is probably less likely than small scale

data would imply. HCU condensed on components would be expected to react

or evaporate after the ambient concentrations were reduced. However,

chloride ions combined with particulate are expected to remain on the

components until physically removed. Corrosion resulting from the

chloride ions is worst when the humidity is high as evidenced by the

counter which was exposed to high humidity and suffered significant

corrosion (see Fig. 30).

4.3.2 Chloride Ions in Exhaust as a Function of Time

The chloride ions measured in the exhaust gas as a function of time

for test 3 are shown in Fig. 35. This figure was obtained after first

processing the raw data to filter the signal, but the data is still

somewhat variable for two major reasons: 1) the chloride ion

concentration is found by using the derivative of the total chloride ions

collected as a function of time and derivatives of experimental data

greatly amplify errors in the measurement and 2) the amount of chloride

ions collected was far below what was expected so the chloride ion probe

did not work in its optimal range, causing further difficulty in obtaining

the derivative of the signal. The data does give an indication of the

levels observed as a function of time. The variation of chloride ion

concentration as a function of time for test 4 was not recorded because of

a problem encountered with the datalogging system. For test 5, the amount

collected was so small that derivative data was impossible to obtain with

any accuracy. Consequently, only the total amounts collected are

presented for the last two tests. These totals, along with other

pertinent data for each test is given in Table 6.

Table 6 shows the low percentage of theoretical chloride ions

collected in all the tests. The data also shows that as the ventilation

rate (expressed in air changes per hour) is increased, the percentage of

theoretical chloride ions increases. Another likely conclusion is that

the smaller the room, the larger the amount of chloride ions collected.

Both these observations seem to make sense. As the ventilation rate is

increased, less time is available for hydrogen chloride/particulate

reactions, and hence more chloride ions are collected. Also, the higher ventilation rates tend to clean out the room more quickly at the end of

the test, leaving fewer chloride ions lost in the room environment at the

end of the test. For example, with one room change per hour, the

exponential decay time constant for reducing the chloride ion

concentration in the room is one hour if the concentration is assumed

uniform at all times. Obviously uniform concentration is not a good

55
250

2i6

E

Q. ISO--

L.

0

t'-

0 1000 2000 3000 4008 5808

Time (seconds)

Fig. 35 Chloride Ion Concentration in Exhaust Duct vs. Time for Test 3
assumption, but it does convey the idea. With larger rooms, more surface

area is available for particulate deposition for a fixed size fire,

resulting in less collected.

Table j Pertinent Data for Chloride Ion Collection

Test Number 3 4 5

Total Chloride Ions Collected (mg) 3.02 * 3.44 0.60

Approximate Weight iurned (kg) 45 50 35

Ventilation Rate (m /min) 68 23 181

Air chinges per hour 14.4 1.0 8.0

Room Size (m ) 283 1360 1360

Amount collected x (ventilation rate/

sample flow rate)/amount burned (mg/g) 4.56 1.57 3.20

Percent of Theoretical Chloride Ions ** 1.6 0.55 1.1

* Corrected for actual sample flowrate which was not constant at 1

liter/minute.

** Assuming about 50% of the cable weight is PVC [13] and 57% of PVC

is chlorides (based on the chemical formula).

57
5.0 CONCLUSIONS

The results of this test program show actual failure or some

indication of failure for the strip chart recorders, the electronic

counters, the oscilloscope amplifier, and the switches and relays. Most

of the expected failure modes of the highest ranked components from

section 2.0 were tested either directly or indirectly in this test

program. The major exception is high voltage breakdown of components. It

should be emphasized that the environmental stresses used in the cabinet

tests were limited to those created by the tests. Several fire

environments remain to be addressed: 1) direct spray from suppression

activities, either manual or automatic, 2) response of cool components to

steam exposure resulting from from suppression activities (although high

humidities were addressed by the humidity exposures, relatively cool

components were never exposed to rapidly changing humidity which would

likely cause condensation, and 3) hydrogen chloride/humidity interactions

(condensation) which could occur prior to the chlorides combining with

particulates. In addition, this test effort did not address failures from

direct fire effects which could cause undesired effects in a power plant,

such as spurious operations of equipment.

The following specific conclusions may be drawn from this study:

1. The counter tested in test 3 and then exposed to high humidity

conditions failed electrically twice. Both failures were apparently a

result of leakage currents on the circuit boards caused by corrosive

action of the chloride containing particulates in a high humidity

environment. The counter had the covers removed during the fire test and

was located where a significant amount of particulate was deposited on the

circuit boards.

2. Two strip chart recorders failed mechanically when particulates

were deposited on the pen slider mechanisms. The first recorder had the

covers removed and failed grossly; the second was cabinet mounted, had the

covers intact., and only one of the three pens failed. No signs of

electrical failures were noted in either case.

3. The 4-channel amplifier experienced errors as high as 20% prior to

its thermal cutout operating and cutting off the output. The degradation

mode of the amplifier was apparently thermal drift because its operation

returned to normal shortly after the test was over.

4. Several instances of high contact resistances were noted for some

switches and relays at the low test voltages used. However, small voltage

stresses were sufficient to overcome the high contact resistances. In

addition, similar high contact resistances were noted on some of the

relays prior to testing.

5. Relays tested to thermal failure failed at temperatures

considerably higher than the temperature levels observed in this series of

tests at typical component locations, such as inside cabinets (other than

the burning cabinet).

58
6. Chlorides generated in the large scale cabinet tests were almost

completely combined with particulates before being exhausted from the

room. The amount of combined chlorides appears to increase with lower

ventilation rates and larger rooms. Consequently, particulate generated

from burning PVC and deposited on components contains a significant

quantity of chlorides.

7. Hydrogen chloride vapor in the air in condensing concentrations

may be less likely than small scale data would imply.

59
6.0 REFERENCES

1. "Fires in Electrical Cables'", Fire International, V. 46, No. 4,

December, 1974.

2.Staller, J. J. and D. A. Colling, "The Aftermath of a Computer

Fire", FJ.UJournal, November, 1977.

3. "Program for Sampling, Analysis, and Cleanup of Residue on

Affected Structures, Systems, and Components," Brown's Ferry Nuclear

Plant, April 12, 1975, Unpublished.

4. Allan, R., "The Great New York Telephone Fire," IMSectu,

June, 1975.

5. "Acid from Burning Plastics is a New Factor in Fire Costs," F.L.A.

Journal, No. 78, 1968.

6. "An International Look at Corrosion Associated with Fires

Involving Plastics," F.P.A. Journal, No. 86, 1969.

7. "Severe Corrosion Damage to Machinery from Smouldering PVC,"

F.P.A. Journal, No. 81, 1969.

8. "Overheated PVC may Cause Corrosion," Electrical Review, V. 181,

No. 26, 1967.

9. "Corrosion from PVC Combustion," FiX& Journal, V. 63, No. 6, 1969.

10. Chavez, J. M., "An Experimental Investigation of the Effects of

Internally Ignited Fires in Nuclear Power Plant Control Cabinets- Part l,"

SAND 86-0336, Sandia National Laboratories, To be Published.

11. Chavez, J. M., "An Experimental Investigation of the Effects of

Internally Ignited Fires in Nuclear Power Plant Control Cabinets- Part 2,"

SAND 86-0336, Sandia National Laboratories, To be Published.

12. Wanless, J. W., "Investigation of Potential Fire-Related Damage

to Safety-Related Equipment in Nuclear Power Plants," NUREG/CR-4310, SAND

85-7247, Contractor Report, NUS Corporation, November, 1985.

13. Tewarson, A., "The Effects of Fire-Exposed Electrical Wiring

Systems on Escape Potential from Buildings, Part 1 - A Literature Review

of Pyrolysis/Combustion Products and Toxicities-Poly(Vinyl Chloride),"

Factory Mutual Research, Serial No. 22491, December, 1975.

60
Appendix A--Chloride Ion Measurement System

The system used to measure the chloride ion concentration in the

exhaust duct of some of the cabinet fire tests consisted of the system

shown in Fig. A.l. A sample of the exhaust gas was taken from the

ventilation exhaust duct and bubbled through a cylinder containing

deionized water stirred gently by a magnetic stirrer. The bubbler was

made by punching a series of small holes in the end of the Teflon line to

keep the bubble size small while also preventing plugging due to

particulate accumulation. The sample temperature and pressure were then

measured and the sample was run through a flow controller which maintained

the correct flowrate as long as excessive plugging did not occur. A

nominal flowrate of 1 liter/minute was maintained in all tests. A chloride

ion electrode and a reference electrode monitored the chloride ion

concentration in the deionized water solution as a function of time. The

chloride ion electrode was shielded from generated bubbles by a glass tube

over the electrode reaching below the level where the bubbles were

generated. The bubble protection was needed for the membrane on the ion

specific electrode; the reference electrode works differently and did not

need to be protected. The detrimental effect of the glass tube was an

increase in the response time of the system to allow for a uniform

chloride ion concentration to be established in the cylinder. Two

additional factors in the system contributed to a relatively high overall

response time. These include 1) the time for the generated chloride ions

to get from the fire, into the room and the ventilation exhaust duct, and

through the approximately five-foot long sample line, and 2) the response

time of the chloride ion electrode which can be up to about one minute.

The system as shown was used in two Factory Mutual Tests. The one

test at Sandia where chloride ions were measured used an earlier version

of this design where the flow controller and pump were upstream of a

beaker used for collection. This eliminated the need to seal all the

equipment which had to go into the beaker (thermocouple, electrodes, and

sample line). The earlier version also had materials other than Teflon in

the sample line prior to the bubbler and a fritted glass bubbler was used

to generate small bubbles. The system was changed because it was believed

that the equipment and sample lines may have been removing many of the

chloride ions prior to their reaching the bubbler. The bubbler was

changed to prevent clogging by particulate. The system was therefore

modified such that no material was in contact with the sample, other than

Teflon, prior to the bubbler. The length of Teflon line was also limited

to five feet.

Both configurations of the chloride ion measurement system were

checked for collection efficiency using hydrogen chloride ion sources.

The original system was checked using bottled anhydrous hydrogen chloride

and the modified system was checked using hydrogen chloride generated by a

heated cable specimen. Two bubblers were used in series and the amount of

chloride ions collected in the first bubbler divided by the amount

collected in both bubblers was taken as the collection efficiency. The

efficiency for the first system with the small bubbles was fouyd to be

much greater than 99% up to concentrations on the order of 10' molar

while the second system using somewhat larger bubbles had an efficienc•

much greater than 99% up to chloride ion concentrations of about 5x10"

molar and an efficiency of at least 99% up to concentrations of 2x10- 2

molar.

61
VENTILATION EXHAUST DUCT

TO DATALOGGER

THERMOCOUPLE

TO DATALOGGER

TO PRESSURE

MEASUREMENT

I FLOWEXHAUST

R ATO DATALOGGER PUMP

- GRADUATED

CYLINDER TO DATALOGGER

-- REFERENCE

ELECTRODE

DEIONIZED CHLORIDE ION

WATER I I :SPECIFIC ELECTRODE

STIRRER

Fig. A-1 Chloride Ion Measurement System
DISTRIBUTION:

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225 copies for RP

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Attn: A. Datta (5)

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Impell Corporation

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Professional Loss Control, Inc.

Attn: Kenneth Dungan, PE

P.O. Box 446

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Electric Power Research Institute

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Attn: Joseph Matte III

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Palo Alto, CA 94304

Dr. Ulrich Heinz Schneider

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Dr. Heinz-Willi Brenig

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BP No 3

Attn: Serge Galant

78373 Plaisir Cedex

France

M. Allen Matteson Jr.

Code 1740.2

Ship Protection Division

Department of the Navy

David W. Taylor Naval Ship

Research and Development Center

Headquarters

Bethesda, Maryland 20084-5000

Mr. David Satterfield

National Center #4, Room 311

Naval Sea System Command (56Y52)

Washington, DC 20362

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NRC FORM 3 UAL NUCLEAR REGULATORY COMMISION I REPORT NUMBER wtwedby TIDC. add Vol No. P Yj)

M 1102.NUREG/CR-4596

3201.3202 BIBUOGRAPHIC DATA SHEET SAND86-0394

SEE INSTRUCTIONS ON THE REVERSE

2. TITLE AND SUBTITLE 3. LEAVE BLANK

SCREENING TESTS OF REPRESENTATIVE NUCLEAR

POWER PLANT COMPONENTS EXPOSED TO SECONDARY 4 DATE REPORT COMPLETED ENVIRONMENTS CREATED BY FIRES MONTH I YEAR

S. AUTHOR(S1

6 DATE REPORT ISSUED

Mark J. Jacobus MONTH YEAR

June 1986 7. PERFORMING ORGANIZATION NAME AND MAILING ADDRESS fociaue Zo C•*J S. PROJECTITASKIWORK UNIT NUMSER

Sandia National Laboratories

Albuquerque, NM 87185 , FIN OR GRANT NUMBER

Al010

10. SPONSORING ORGANIZATION NAME AND MAILING ADDRESS (ImeAWZOC60 Ili TYPE OF REPORT

Division of Engineering Technology Technical

Office of Nuclear Regulatory Research

U.S. Nuclear Regulatory Commission b PERIOD COVERED I.f-..,w.,i

Washington, DC 20555

12 SUPPLEMENTARY NOTES

13. ABSTRACT 1200 wOwf 61!'MeJ

This report presents results of screening tests to determine component

survivability in secondary environments created by fires, specifically

increased temperatures, increased humidity, and the presence of

particulates and corrosive vapors. Additionally, chloride concentrations

were measured in the exhaust from several of the tests used to provide

fire environments. Results show actual failure or some indication of

failure for strip chart recorders, electronic counters, an oscilloscope

amplifier, and switches and relays. The chart recorder failures resulted

from accumulation of particulates on the pen slider mechanisms. The

electronic counter experienced leakage current failures on circuit boards

after the fire exposure and exposure to high humidity. The oscilloscope

amplifier experienced thermal-related drift as high as 20% before thermal

protective circuitry shut the unit down. In some cases, switches and

relays experienced high contact resistances with the low voltages levels

used for the measurements. Finally, relays tested to thermal failure

experienced various failures, all at temperatures ranging from 150 0 C to

above 3500 C. The chloride measurements show that most of the hydrogen

chloride generated in the test fires is combined with particulate by the

time it reaches the exhaust duct, indicating that hydrogen chloride

condensation may be less likely than small scale data implies. 14 DOCUMENT ANALYSIS-a KEYWORDSIOESCRIPTORS IS AVAILABILITY

STATEMENT

Unlimited

16 SECURITY CLASSIFICATION

(ra, 00"I

b IDENTIFIERSOPEN-ENDED TERMS Une"I ] a si f i t-c'

(TA.•.a ,vow

Unclassified

I? NUMBER OF PAGES

73

1S PRICE