ML20045A722

Forwards Draft NUREG Rept, Phase I Aging Assessment of Essential HVAC Chillers Used in Nuclear Power Plants, to Be Placed in Public Document Room

ML20045A722
Person / Time
Issue date:	01/31/1993
From:	Burns J NRC OFFICE OF NUCLEAR REGULATORY RESEARCH (RES)
To:	NRC
References
NUDOCS 9306110267
Download: ML20045A722 (99)

Text

ws

2l, 1

7,,

gjs UNITED STATES NUCLEAR REGULATORY COMMISSION -

g 3~

I-WASHINGTON, D. C. 20555 A ***** 4 Memorandum to:

Public Document Room From:

John J. Burns, Jr.

Senior' Mechanical Engineer' Electrical and Mechanical Engineering Branch Division of Engineering, RES

Subject:

DRAFT NUREG REPORT, " PHASE I AGING ASSESSMENT OF ESSENTIAL HVAC CHILLERS USED IN NUCLEAR POWER PLANTS" Please place the subject contractor draft NUREG report into the Public e

Document Room.

d J hn J. Bur ', Jr.

enior Mechanical Engineer Electrical and Mechanical Engineering. Branch Division of Engineering, RES

Enclosure:

E As stated E

d n

f }.-

Re E

r.e... -

d

~ ~ ~ '

. e.. e, - ~ r -.

... t v.

090CC7 p

9306110267 930131

[

'PDR ORG NREA I-

C.

bas,-ses m

1ll NUREG/CR-xxxx.

.PNL-XXXX 5

PHASE.I AGING ASSESSMENT OF

--l' ESSENTIAL HVAC CHILLERS

.USED IN NUCLEAR POWER PLANTS I

I.

D. E. Blahnik R. F. Klein i

I January 1993 Prepared for the I

Division of Engin eri Office of Nuclear gu a ry Research U.S. Nuc ar Regula ry omission I

under E

tract D C- -76RLO 1830 I

Pa ic No hw t Laboratory chl

, Was ington 99352 l

LIMITED DISTRIBUTION NOTIG This document co nce it is transmitted in advance of patent clearance, -is '

l made available in nfidence solely for use in performance of work under contracts with the U.S. Nuclear Regulatory Comission. This document is not to be published nor its contents otherwise disseminated or used for purposes

'l-.

.other than specified above before patent approval for such release or use has been secured, upon request, from Patent Services, Pacific Northwest Laboratory, Richland, Washington 99352.

-l-l u

I ABSTRACT in-The Pacific Northwest Laboratory conducted a Phase I aging assessment of' cg chillers used in the essential safety air-conditioning systems of nuclear.

power plants. Centrifugal chillers in the 75 to 750 ton refrigeration capacity range are the predominant type used. The chillers used, and air-conditioning systems served, vary in design from plant-to-plant. It is crucial to keep chiller internals very clean and to prevent the leakage' of water, air,-

and other contaminants into the refrigerant containment system.

Periodic

~3 operation on a weekly or monthly basis is necessary to remove-moisture and g

non-condensable gases which gradually build up inside the chiller. This is especially desirable if a chiller is required to operate only as an emergency '

standby unit.

I The primary stressors and aging mechanisms that affect chillers include vibration, excessive temperatures and pressures, thermal cycling, chemical i

I attack, and poor quality cooling water. Aging is accelerated by moisture, non-condensable gases (e.g., air), dirt, and other contamination within the refrigerant containment system, excessive start /stop cycling, and operating 3

below the rated capacity. Aging is also accelerated by corrosion and fouling g

of the condenser and evaporator tubes. The principal cause of chiller failures is lack of adequate monitoring.

Lack of performing scheduled maintenance and human errors also contribute to failures.

I I

I

q I

4

I E

I I

I

I CONTENTS l

ABSTRACT.........................................................

4

SUMMARY

vii ACKNOWLEDGEMENTS.................................................

x ACRONYMS.........................................................

xi-i DEFINITIONS......................................................

xiii

l

1.0 INTRODUCTION

I

1.1 BACKGROUND

I 1.2 OBJECTIVE..................................................

2 1.3 EQUIPMENT B0UNDARY SELECTION...............................

2 2.0 BASIC CHILLER AND HVAC SYSTEMS INFORMATION...................

4 2.1 CHILLERS IN INDUSTRY AND COMMERCE..........................

4 2.2 CHILLERS IN LWRs...........................................

7 2.3 ESSENTIAL CHILLER HVAC SYSTEMS IN LWRs....................

8 3.0 REGULATORY, CODE, AND STANDARDS REQUIREMENTS FOR ESSENTIAL CHILLERS.....................................................

10 4.0 CENTRIFUGAL CHILLER DESCRIPTION...............................

14 4.1 CHILLER DESIGN............................................

14 4.2 MATERIALS OF CONSTRUCTION..................................

14 5.0 OPERATING EXPERIENCE DATABASE EVALUATION.....................

23 5.1 LICENSEE EVENT REPORTS (LERs) DATABASE.....................

23 5.2 NUCLEAR POWER EXPERIENCE (NPE) DATABASE....................

24 5.3 IN-PLANT RELIABILITY DATA SYSTEM (IPRDS) DATABASE..........

25 5.4 NUCLEAR PLANT RELIABILITY DATA SYSTEM (NPRDS) DATABASE.....

26 6.0 OTHER OPERATING EXPERIENCE...................................

27 6.1 PACIFIC NORTHWEST LABORATORY (PNL) EXPERIENCE..............

27 lii I

r

.I

!I<

6.2 WESTINGHOUSE HANFORD' COMPANY EXPERIENCE....................

28 a'

6.3 REGIONAL SERVICE COMPANY EXPERIENCE........................

29 g

6.4 COOPERATING UTILITY EXPERIENCE.............................

31 6.5 EXPERIENCE FROM LITERATURE REVIEWS.........................

32 7.0 OPERATING EXPERIENCE

SUMMARY

AND DISCUSSION.................

35

8.0 CONCLUSION

S..................................................

38 9.0 RECOMMENDATIONS..............................................

40

10.0 REFERENCES

41-APPENDIX A: LWR PLANT CHILLER SYSTEMS DESCRIPTION (FSAR DATA)....

A.1 APPENDIX B: HERMETIC CENTRIFUGAL CHILLER FUNCTIONAL DESCRIPTION.

B.1 APPENDIX C: LWR PLANT LER REVIEW

SUMMARY

C.1 APPENDIX D: NPE DATABASE ON CHILLERS.............................

D.1 APPENDIX E: IPRDS DATABASE MAINTENANCE REPORT

SUMMARY

FOR NUCLEAR E.1 POWER PLANT A-'........................................

APPENDIX F: CHILLER WORK REQUEST

SUMMARY

FOR NUCLEAR POWER PLANT B F.1 APPENDIX G: ANS PAPER COMPARING SAFETY AND NON-SAFETY CHILLERS...

G.1 I

I I

lI I

m I

I FIGURES 1.1 Research Boundary for Phase I Essential Chiller Study......

3 Centrifugal Water Chiller Description......................

5 2.1 l

2.2 Reciprocating Water Chiller Description....................

5 2.3 Screw Water Chiller Description............................

6 2.4 Absorption Water Chiller Description.......................

6 4.1 Current Model of Liquid Hermetic Centrifugal Chiller I.

Manufactured by the Carrier Corporation - Reference Design..

15 4.2 Current Model of Liquid Hermetic Centrifudal Chiller Manufactured by the York International Corporation.........

16

!IE 4.3 Current Model of Liquid Hermetic Centrifugal Chiller Manufactured by The Trane Company..........................

16

(

4.4 Reference Carrier Chiller Cross-Sectional View with the Refrigerant Flow Path......................................

17 4.5 Reference Carrier Chiller Compressor Cross-Section.........

18 4.6 Reference Carrier Chiller Purge Unit........................

18 4.7 Reference Carrier Chiller Piping and Wiring Illustration....

_19 4.8 Reference Carrier Chiller Dimensions and Layout Requirements.

20 4.9 Current Model of Liquid Op_en Centrifugal Chiller Manufactured l

by the Carrier Corporation (shown to contrast with hermetic l

centrifugal chiller shown in Figure 4.1)...................

21 7.1 Summary of Chiller Failures (LER and NPE Databases).........

36 7.2 Aging Versus Nonaging Related Chiller Failures..............

36 l

TABLES 5.1 Summary of Chiller Failures in the LER Database.............

23 5.2 Summary of Chiller Failures in the NPE Database.............

24 5.3 Summary of Pl ant A Essential Chiller Failures...............

25 i

I I

SUMMARY

.a The Pacific Northwest Laboratory (*) conducted a Phase I aging j.

assessment of chillers used in essential safety HVAC systems of nuclear power l

plants. Searches of traditional nuclear plant databases provided limited information on chillers. The information was heavily augmented by. non-nuclear operating experience. More direct nuclear piant information will be incorporated in the Phase II portion of the aging study.

,I Centrifugal chillers in the 75 to 750 ton refrigeration capacity range are the predominant type used in essential nuclear plant HVAC systems. Other, L

less-used types include rotary, screw, and reciprocating chillers. There are

'a three primary manufacturers and many models from each of them. The chillers g

used, and HVAC systems served, vary in design from plant-to-plant.

It is difficult to select a generic design. This study focused on centrifugal l

packaged chillers.

I-1 Although centrifugal chillers are relatively complex equipment packages I

[

they are usually designed for a lifetime of 40 years or more.

They will-exceed this lifetime if operations, maintenance, service water, and operating i

I.

environment are properly managed and controlled. Units that are approaching

~

60 years of age are still operating in cold storage plants.

Major overhaul and maintenance that requires entering the freon contain-ment region must be performed carefully by well trained technicians. ' A small

[g amount of contamination, or a damaged or misaligned part, can cause major damage during operation of the chiller.

It is crucial to keep equipment internals very clean and to prevent the leakage of water, air, and other l3 contaminants into the refrigerant containment system.

Periodic operation on a weekly or monthly basis is necessary to remove moisture and non-condensable gases which gradually build up inside the chiller, especially if a chiller is required to operate only as an emergency standby unit.

If multiple chillers l.

are available, the operation should be alternated, and the operating hours of use should be balanced. The chiller should be operated as close to 100%

capacity as practical to minimize aging.- Usually chillers are replaced due to s

L lack of adequate monitoring and maintenance. Other causes for replacement (obsolescence) are:

1) change of heat load (usually growth), 2) energy I

efficiency improvements, and currently 3) incompatibility with the new L

refrigerants required by new regulations.

In many cases the chillers can be upgraded by installing adaptor equipment packages provided by the manufacturer.

Chillers used in both nuclear and non-nuclear applications will soon be I

affected, and in some cases become obsolete, due to environmental regulations which require changing to use of alternative refrigerants. The impacts of the L

new refrigerants on the performance and life of chillers is not completely known. Currently the main concerns are potential efficiency loss, incompatible materials and design, and the aggressive nature of the new I

(a)

Operated for the U.S. Department of Energy by Battelle Memorial Institute under Contract DE-AC06-76RLO 1830.

I vii l

l-L

II l

refrigerants.

Chiller owners are encouraged to work with the chiller j

manufacturer to make satisfactory modifications.

Factors related to the aging of chillers are vibration, operation at excessive temperatures and pressures, thermal cycling, chemical attack, and L

poor quality condenser cooling water. Aging is accelerated by moisture, non-condensable gases (e.g., air), dirt, and other contamination within the J

refrigerant containment system.

Excessive start /stop cycling and under-loading of chillers cause accelerated aging. Aging is also accelerated by corrosion and fouling of the condenser and evaporator tubes. The principal cause of premature chiller failures is lack of adequate monitoring.

Lack of performing scheduled maintenance and human errors also contribute to failures.

Failures due to design, procedure, and manufacturing discrepancies usually occur during the start-up, shakedown, or first year of operation for a particular new chiller model. The time between recommended major overhauls (3 to 10 years) is usually established by the life of seals and gaskets.

Based upon the results of this study, it is apparent that essential (safety-related) chillers are important to cool the control room and other essential equipment rooms. The cooling is needed to prevent degradation and failure of safety-related equipment, to protect safety personnel, and to prevent or mitigate events and accidents. Adequate control of temperature and L

humidity in these rooms is very important.

Therefore, the essential chillers play an important role in nuclear plant safety and warrant a more in-depth Phase II study.

i Based upon the regulatory safety documentation reviewed during the course of this study, the following' recommendations are given:

t The aging degradation effects on electrical, electronic, and computer components housed in cabinets, due to the excessive temperatures, humidity, and vibration expected in the control room, need to be evaluated. Actual temperature checks should be made and extrapolated to the maximum temperature expected. Also, component exposure to condensation during rapid cooldown of the control room should be evaluated.

Requiring transient thermal calculations for safety-related equipment rooms to determine heat-up rates following a loss of room cooling should t

be considered. There should be a follow-up with actual test measurements in the room and inside cabinets.

Use of a remote modern HVAC ice storage unit to provide buffer cooling i

storage should be considered. An additional 12 to 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> of passive cooling capacity would help relieve the burden of plant de-rating and i

prevent exceeding the Limiting Conditions of Operation (LCO) time.

In the case of events or accidents where off-site power is not lost, an additional remote chiller could be on line to keep the ice supply replenished.

This would greatly improve the plant reliability and safety if it is kept simple. A cost / benefit study would be needed to justify serious consideration of the storage system.

viii

~

________._______________w

'1 Addressing temperature and-humidity limitations in safety-related room -

requirements and specifications should be considered.

Human factors limitations also should be considered along with the impacts on aging I

and reliability of the safety equipment.

I k

cg ll I

ll il lI

\\E q

I I

I lI

E ACKNOWLEDGEMENTS The authors' of this report acknowledge the support and technical r

guidance of Dr. J. J. Burns, Jr., of the Nuclear Ragulatory Commission, during the course of this research under the Nuclear Plant Aging Research Program.

C. Michelson, an Advisory Committee on Reactor Safeguards member at NRC, and other NRC staff provided information'important to the study. Dr. R. P. Allen of PNL provided the project management support and guidance for the study.

We extend our appreciation to Dr. A. B. Johnson, Jr. and Dr. I. S. Levy, also F

of PNL, for their assistance in the Pre-Phase I prioritization of the essential chillers for further study. The Oak Ridge National Laboratory provided initial information from their SCSS, IPRDS, and NPE Databases.

D. D. Hatley and H. D. Steele of PNL and B. G. Berglin and J. D. Fulcher of L

Westinghouse Hanford Company provided valuable insights by sharing their experience in the installation, start-up, operation, and maintenance of chillers.

T. W. Camp of Landis & Gyr Powers, Inc. utilized his 25 years experience of " hands on" trouble shooting and rebuilding chillers throughout i

the Pacific Northwest to help provide a preliminary assessment of chiller aging. He also answered many of our questions on chillers. A cooperating nuclear plant provided us with a tour of the plant's chiller HVAC facilities, and with helpful information on the plant's chiller HVAC operating and maintenance experience. The PNL Technical Library staff performed an extensive literature search on chillers.

Regional chiller manufacturing

[

representatives provided us with equipment catalogs.

j r

L F

1

?

x n___---_-______________

z I

ACRONYMS l

ANS American Nuclear Society l'

ARI Air-Conditioning and Refrigeration Institute ASHRAE American Society of Heating, Refrigerating, and Air-Conditioning Engineers ASME American Society of Mechanical Engineers l-CCW Component Cooling Water System 1

8 1

ECW Emergency Cooling Water System f

4 ESF Engineered Safety Features

}

FFTF Fast Flux Test Facility FSAR Final Safety Analysis Report HX Heat exchanger HVAC Heating, ventilating, and Air-conditioning Institute of Electrical and Electronic Engineers IEEE IPRDS In-Plant Reliability Data System (Database)

LCO Limiting Condition of Operation LER Licensee Event Report (Database)

LOCA Loss of coolant accident I

LOP Loss of power LWR Light-water reactor j

l NDT Nondestructive testing I

NPAR Nuclear Plant Aging Research NPE Nuclear Power Experience (Database) l-NPP Nuclear Power Plant NPRDS Nuclear Plant Reliability Data System (Database)

NRC U.S. Nuclear Regulatory Commission xi il t

I NUDOCS/AD Nuclear Documentation System (Database)

- O&M Operating and maintenance f

PNL Pacific Northwest Laboratory PTS Plant Technical Specifications RHR Residual Heat Removal RIDS Regulatory Information Distribution System (Database)

SAR Safety Analysis Report

,8 SCSS Sequence Coding and Search Systems (Database)

SI Safety Injection L

TIRGALEX Technical Integration Review Group for Aging and Life Extension

I

.I

.I I

i I

I u

1 I

I iI k

xii

l l.

DEFINITIONS l

Chiller Packaged refrigeration machine used to chill water that is pumped to the HVAC room cooler to cool room air.

The absorbed heat is returned to the chiller, which transfers the heat to a plant ' cooling system.

Essential Chiller A chiller used to cool rooms which contain safety-related equipment that are essential to plant safety.

Safety-Related Items Defined by 10 CFR 50, Appendix A, as "Those structures, systems, and components that provide I

reasonable assurance that the facility can be operated without undue risk to the health and safety of the publ i c. " For details, see 10 CFR 50.49.

Ton, cooling rate Standard ton of refrigeration is equivalent to an air conditioning capacity of 12,000 BTU /hr.

Ton, storage Storage equivalent to the heat of fusion of 2000 pounds of ice (2000 pounds X 144 Btu / pound - 288,000 Btu to melt a ton of ice).

I I

lI lI i

i I

l l

i l

I lI 1

xiii f.

i 1

i L-J

I

1.0 INTRODUCTION

The essential chillers provide chilled water to cool the control room l

and other rooms containing safety-related equipment and personnel at nuclear power plants (NPPs).

Essential chiller operability is mandated by Title 10, Part 50 of the Code of Federal Regulations and other regulations that govern lI habitability of the control room and operation of the safety-related rooms, The essential chilled water systems must be available at all times, have redundancy, and function during and after simultaneous or individual events, such as a safe shutdown earthquake, loss of coolant accident (LOCA), or loss I

of off-site power.

Since the ventilation systems they serve are safety-related, the chillers are also safety-related. The chillers must be designed, manufactured, and installed in accordance with Seismic Category I, American Society of Mechanical Engineers (ASME) Code,Section III, Class 3 requirements.

The system must be powered from seismic category lE buses.

L With the above requirements in mind, work was initiated on a Nuclear

!m Plant Aging Research (NPAR) Phase I aging study of NPP chillers. The g

discussion below outlines the background, objectives, and initial boundary l

selected for the study.

1.1 BACKGROUND

Chillers were first formally identified as a candidate for an NPAR study

n in a Nuclear Regulatory Commission (NRC) prioritization study (Levy 1988).

In g

January 1991, work was initiated on a Pre-Phase I study to determine if a full j

Phase I study was justified. The Pre-Phase I study was completed and summarized in a letter report (Blahnik 1991).

The study recommended that a full Phase I study proceed, and the NRC l

concurred. The recommendation was based upon the following reasons:

The Technical Integration Review Group for Aging and Life Extension l

(TIRGALEX) component prioritization study recommended an aging assessment of chillers. Most U.S. nuclear power plants are affected by this issue.

NRC Generic letter 89-13 stresses the importance and concern for chiller HVAC and room cooler heat exchanger performance in safety systems.

l NRC Generic Safety Issue No. 143, Availability of Chilled Water Systems and Room Coolino, is concerned with the availability of cooling services I

provided by chilled water, HVAC systems, and related auxiliaries to provide temperature control in rooms with safety-related equipment.

Review of draft reports and general literature indicated the importance i

of chillers in cooling safety-related rooms.

High temperatures and humidities in control rooms affect both personnel and equipment. High temperatures can cause operators to become uncomfortable and more susceptible to losing alertness and making errors in judgement.

High 11 I

I control room temperatures also cause concern for premature degradation and failure of electrical and electronic components, which are often housed in cabinets with even higher temperatures.

Failures of' control I

components and spurious alarms make the operators' job even more difficult and could set the stage for being the principal cause of a major accident. The situation is difficult during a limiting condition

[

of operation (LCO) when only one chiller is available.

Operators become much more tense when the remaining chiller becomes inoperable.

Preliminary review of Licensee Event Reports (LER), Nuclear Power I

Experience (NPE), and In-Plant Reliability Data System (IPRDS) data indicated that chillers are subject to age-related degradation with failures resulting from the degradation.

Each year a few plants must reduce power or shut down because essential chillers are unavailable to cool the control room and other safety equipment rooms.

I The full Phase I NPAR aging study was initiated in October 1991 and completed in September 1992, with the results summarized in this report.

1.2 OBJECTIVE The objective of the Phase I chiller study was to make an interim aging assessment of chillers. The following standard research elements were performed in accordance with the NPAR Program strategy (USNRC 1991):

Review and analyze available information from chiller designs,

. specifications, operational parameters, and ongoing research.

Evaluate chiller operating experience from readily available databases j

(e.g., IPRDS, NPE, and LERs).

4 I

i Utilize industry practices and the knowledge from experts on chillers.

Characterize the aging mechanisms for chillers.

]

I Interact with key NRC staff involved with chillers.

1.3 E0VIPMENT BOUNDARY SELECTION A simplified diagram of the major components of a chiller and the I

interfacing systems is shown in Figure 1.1.

The research boundary selected for the Phase I study is indicated by the dashed line. The major components of the chiller are typically a motor driven centrifugal compressor, a

,I condenser heat exchanger, an expansion device, and the evaporator-cooler heat exchanger. The refrigerant used as heat transfer media is usually R11 or R12 freon. The chiller waste heat is removed by the plant ' service water system or an emergency cooling water system (especially in an accident or loss of off-lI site power situation). The chilled water from the evaporator is used to cool rooms that house safety-related equipment and personnel. The rooms cooled are plant specific, but the control rooms are probably always included. The I

chiller and its interfacing systems (the cooling water system, chilled water system, and electric motor control center) can have a large effect on the I

I

l performance of each other.

In reality, a chiller is much more complex than shown in Figure 1.1.

A chiller has hundreds of components and is inter-related with many remote safety system controlled components.

I-The typical auxiliary components that comprise a chiller include lubrication oil system (*)

compressor guide vane control panels and indicators sensors, controls, and alarms j.

wires and terminals switchgear, starter, relays purge-dehydrator unit ')

flash economizer *)

l I

I piping and tubing relief valves seals and gaskets transmission gearbox and couplings base, package support structure, and vibration dampeners.

I (a) These components have numerous sub-components.

h Safety Equipment Rooms Chilled Water l

g-________________+_______________________+_________l' l

Cooler (Evaporator)

Electrici l\\

Motor 4 1NPAR Control i i

n l Research Center i

__ X E

i Boundary i

M tor u Compressor De ce i

Condenser g

{_________n L

,,__3 Condenser Water y

Auxiliary Service and/or Components Emergency Water Systerr l

FIGURE 1.1.

Research Boundary for Phase l' Essential Chiller Study 3

I I

E l[

2.0 BASIC CHILLER AND HVAC SYSTEMS INFORMATION Chillers are used for numerous applications. and are used extensively

.I'-

throughout developed portions of the world.

Probably about 250,000 liquid cooling chillers are.in use today. Approximately 80,000 are used in the U.S.

alone. Most of the chillers are used in central HVAC applications where it is more economical and efficient to distribute chilled water to remote air handling units than to use large space-consuming air ducts of a central air handler (Niess 1992). The temperature is better controlled by modulating chilled water flow through air-cooling coils than _with a direct "on-off" I-expansion refrigerant distribution control.

2.1 CHILLERS IN INDUSTRY AND COMMERCE Liquid chillers are used to cool water, glycol mixtures, or brines for central station air-conditioning systems, refrigeration, or process cooling.

I Nearly 90% of the chillers used in industry provide water-based liquids for' central station air-conditioning systems (Stebbins 1991).

The most common chiller systems' utilize centrifugal, reciprocating, or I

screw compressors. Most of the chillers use freon or ammonia (usually not used in rooms or buildings occupied by personnel) in a closed refrigerant cycle. They use air, water or evaporative condensers, and flooded or direct-

I-expansion evaporators.

Hermetic or open drives, expansion devices, and controls complete the typical package. Other, less common systems used, are the rotary and absorption cycle (water / steam) chillers.

Illustrations of the various chiller designs and the absorption chiller concept are provided in-I Figures 2.1 through 2.4.

Reciprocating chillers are available in sizes up to 200 tons and screw-compressor units are available in sizes between 50 and 750 tons. Centrifugal chillers, the industry work horse, provide'a' broad range of sizes between 75 and 5000 tons or more.

The largest is believed to be 10,000 tons of refrig-eration.

Most of the chillers used in industrial and commercial HVAC applications are centrifugal chillers.. About 80% use CFC-11' refrigerant..CFC-12, also widely used in supermarket refrigeration and automobile air-conditioning, is used in about 15% of the centrifugal chillers. - The balance' of the-centrifugal chillers use R-500, CFC-114, and HCFC-22 refrigerant (Niess 1992). The CFC I

refrigerants (CFC-11, CFC-12, and CFC-114) will be phased out by the year 2000, to meet current environmental control regulations established by the U.S. Congress Clean Air Act Amendments of 1990. The regulations were instituted to reduce degradation of the stratosphere ozone due to chlorine (Calm 1992). These regulations will also apply to the nuclear-industry.

Alternative refrigerants HCFC-123 will likely replace CFC-11, and HFC-134a will likely replace CFC-12 (Clark 1991). The replacement for CFC-114 will I.

likely be HCFC-124 for at least the short term.

I I

I i

i

F 3

I I'.

I Fig. 4. Centrifugal watEchillers are available in a broad range of sizes between 75 and 5000 tons or more. The compressor is a variable-volume displacement machine with one or triore rotating impellers imparting centrifugal force to compress the refrig-erant vapor. The knetic energy created by the centrifugal force is converted into pressure. Because they are not constant volume machines, centrifugal compressors l

offer a wide range of capacities continuously modulated over a limited range of pres-i sure ratios and can provide chdled water over a wide range of temperatures. (Courte-

]

sy Westinghouse Heating and Cooling Div.) -

.; Q.

l y,i.-

~ -9

y..~

337 w ? e,, 4 b ?h

.e.

l

n.. y a,

ps u.i s..

.~

.. a

,.u.

p.

.g c

- I k.. fN.g M. Q @vjh 3 %,.

Q;

.u.a J

- 5

,., (.. :,. ;

-a 1

s.

w....

I.

g.%,n.,

u:.,,

n w. w. ~ w, I ~

EJGURE 2.1.

Centrifugal Water Chiller Description (Permission to use graphic is pending.).

1 W 'y

[

Y

&'Y

~-

, + -

=m..

'y I

. s,

.,. 9 _>

w.

f y'

• s

~

v k,,b x'..s

- - [,

h

^

y g

E g.f'!c

~

%b kb t.

Fig. 3. Reciprocating water chillers are available in sizes up to 200 tons. The com-1 pressor is a positive-displacement machine with crankshaft-powered pistons working in cytenders equipped with suction and discharge valves. These compressors maintain l

' I' fairly constant flow rates over a wide range of pressure ratios and may be used when displacement volumes are small. They operate efficiently at high condensing tempera-tures and high compressen ratios. (Courtesy McQuay Group McQuay-Perfex, Inc.)

FIGURE 2.2.

Reciprocating Water Chiller Description (Permission to use graphic'is pending.)

5 I

1

_A

'+.

3 J k"'f p; __

. AE

.w-r N_.

o

,,m q

N

. s, M,

,m r

Y W

i ig 7

,4, J

' ~

,t t

Fig. 5. Screw water chillers are available in sizes between 50 and 750 tons. The j

compressor is a positive-displacement machine with internal compression, nearly con.

stant flow performance, and increrrental capacity modulation. Compression results '

i from the meshing action of grooved, precision michined lobes on the male and female i

rotors. Efficiency of the machine is increased by direct injection of oilinto the compres-sson area to seal the spaces between the two rotors and between the rotors and -

e casing. (Courtesy Dunham-Bush, Inc.)

i 1

FIGURE 2.3.

Screw Water Chiller Description (Permission to use graphic is pending.).

!I

% 5:

&},

y

- s

_-~

ll

PM,,,,.1,%

/ /eg 4- '" A,%

4 m

a

_ w,

~-

hq,eao3: 7 ';, ' ~ :_

f f

i3 in,

~y 3 =. :.;gww-n -

_ Qg I

W@#d i

MMWein34

. I usesseremosmee"w -

y y

4 1,,,~y a.n; w m

x p sees,$menes w w sep.ma g 2.;,- --- --.

se

- l

-FIGURE-2.4. Absorption Water Chiller Description (Permission to use graphic is pending.)

.f 6

I

I

-2.2 CHILLERS IN LWRs General descriptions.of chillers and the systems they serve in light-I!.

water reactor (LWR) NPPs are.provided in Appendix A of this report. The descriptions are based upon information found in Final Safety Analysis Reports (FSARs) of U.S. NPPs.

Chiller information was not found in many of the FSARs I-that were reviewed. A comprehensive survey of all the plants would be required to get exact, up-to-date descriptions. However, it is believed that this information is sufficient to be a representative sample of typical systems that are served by chillers in the U.S.

Most of the plants listed in Appendix A had at least two essential chillers that serve safety systems in the control rooms and various equipment I

rooms.

One chiller serves as a backup. The essential chillers were identified with an asterisk. The non-essential or non-safety chiller systems were also listed (without an asterisk), but this study focused on the essential chillers.

Centrifugal chillers were the predominant type of chiller used in LWRs.

Most centrifugal chillers were hermetic drive (electric drive motor is sealed l

inside the refrigerant boundary). Some were open drive (sealed outside the j

refrigerant boundary and exposed to the chiller room environment), but other types of chillers used included screw, rotary, and reciprocating chillers.

These types tended to be used in older and smaller plants. One plant used a.

8 l

hot water absorption chiller in a containment cooling system.

The NPP l-chillers that were found'all used liquid cooling and none used air cooling.

The essential chillers were sized in the 50 to 750 ton refrigeration i

capacity range.

Non-essential chillers were in the 200 to 1500 ton range.

l 1

Based upon what was learned from the FSARs, it was decided to focus on Hl centrifugal hermetic chillers during the Phase I aging study.

l The review of the FSARs in Appendix A also provided the following i

I

}

information:

In some cases essential chillers and their chilled water system are normally on standby for emergency situations (e.g., LOCA, loss of power (LOP),etc.) During normal operations non-essential (non-safety) chillers serve the control room and other safety-related rooms.

In many cases the essential chillers are used for both normal operations and emergency situations to cool just safety-related rooms.

Sometimes the essential chillers serve both safety and non-safety related rooms and

,I.

they reduce their capacity in an emergency to serve just the safety-related rooms.

Essential chiller condenser cooling water is supplied by systems and

m

{

arrangements such as the following:

I l

- Service Water System (both normal and emergency)

Service Water Systen during normal operation and Emergency Service I

Io

. ~

i 1

Water System during emergencies Component Cooling Water System-(both normal and emergency)

I

- Nuclear Closed Cooling System (normal) and Emergency Closed I

Cooling System (emergency)

No cooling water system found for normal operation'and the Emergency

{

Nuclear Service Cooling Water system during emergencies No cooling water system found for normal operation and the. Essential Cooling Water System used during emergencies 1

- Plant Service Water System during normal operations and Shutdown Service Water System during emergencies I

The South Texas Plants have two chillers serving each safety-related HVAC train (total of four). The Perry 1 Plant has three chillers serving two safety-related trains. The third chiller is used as a standby unit. All other plants have one chiller serving each of the two I.

trains.

p The Comanche Peak I plant has two chillers serving the two safety-jI related trains. Comanche Peak 2 is supposed to have the same arrangement. However, the non-safety-related chillers are to be shared by the two plants.

Based upon the results of the FSAR reviews above,.it was determined that l

generic plants do not exist.

Even multiple plants at a site may have substantial design differences.

Perhaps a study to determine which design jl options work the most reliably would be justified.

Plants like River Bend (discussed later in this report) might be helped by such a study.

LE

.In addition to the chiller systems that serve HVAC applications, 5'

(Appendix A), there are other chillers which serve safety systems.in non-HVAC applications.

Examples are chillers used to recover condensible off-gas from

g the primary water system in every plant and to make and maintain ice.for

..{

'g containment safety condensers in eight of the Westinghouse LWRs. The review i

and aging assessment of those chillers were beyond the scope of this study.

I In addition to chiller cooling of essential safety-related rooms, some plants have the option to use water directly from the service water system or other intermediate system in lieu of chiller cooled water.

In one plant service water is cool enough the year around to keep the control room below I'

29 C (85'F).

p 2.3 ESSENTIAL CHILLER HVAC SYSTEMS IN LWRs The primary systems served by the essential chillers are listed in Appendix A.

However, during an emergency the name of the particular. systems

,I.

served varies from plant-to-plant.- The control room was served by an essential HVAC system in all of the plants listed. However, the other rooms I

~

LI

1 served by the essential HVAC-system varied from plant-to-plant.

Examples of

, the rooms and equipment served in various plants include the.following:

Containment Fan Coolers Electrical Equipment Room Battery Room

I Auxiliary Building Electrical Switchgear Room-ESF Switchgear Room Electrical Penetration Room ESF Equipment Room ECW Pump Rooms Auxiliary Feedwater Pump Rooms Reactor Makeup Water and Boric Acid Transfer Pump Cubicles Relay Room

~

Cable Spreadi g Room Computer Room Control Room HVAC Equipment Room

g Relay Room 3

Remote Shutdown Room CCW, Charging, SI, CS, and RHR pump room fan / coil coolers Essential Equipment Rooms SGTS Compartment and Area Spent Fuel' Pool Heat Exchanger and Pump Rooms I-Auxiliary Building ESF Equipment, Switchgear, and Electrical Equipment Protection Room Safety Related Panel Room Emergency Motor Control Center D

il

I I

I:

I I

(b)

In some plants the Computer Room is not con'sidered safety-related.

9 I

a I

3.0 REGUiATORY. CODE. AND STANDARDS REQUIREMENTS FOR ESSENTIAL CHILLERS Lg-The regulatory, code, and standards requirements for essential chillers are outlined below.

g' l

Nuclear Reculatory Reauirements The following nuclear codes and standards apply to esse.tial chillers and the chilled water system they serve:

1.

Title 10 of the Code of Federal Regulations, Part 50 Domestic Licensing of Production and Utilization Facilities, Appendix A General Design Criteria for Nuclear Power Plants (10CFR50, Appendix A).

The following

'f General Design Criterion applies:

Criterion 2 - Design bases for protection against natural phenomena

'E_

Criterion 4 - Environmental and dynamic effects design bases 5

Criterion 5 - Sharing of structures, systems, and components Criterion 19 - Control Room Criterion 44 - Cooling Water I

Criterion 45 - Inspection of Cooling Water Criterion 46 - Testing of Cooling Water.

2.

Codes and Standards (10CFR50.55a)

.3.

Standard Review Plan (NUREG-0800)

SRP 6.4

- Control Room Habitability Systems SRP 9.4.1 - Control Room Area Ventilation System SRP 9.4.2 - Spent Fuel Pool Area Ventilation System (Few Plants)

SRP 9.4.3 - Auxiliary and Radwaste Building Ventilation Systems (Some Plants)

SRP 9.4.5 - Engineered Safety Feature Area Ventilation System (Many Plants) 4.

A Review of Regulatory Requirements Governing Control Room Habitability (NUREG/CR-3786) 5.

Nuclear Regulatory Commission Regulatory Guides RG 1.26 - Quality Group Classifications and Standards for Water, Steam, and Radioactive-Waste-Containing Components of Nuclear Power.

Plants-3 RG 1.29 - Seismic Design Classification E

RG 1.32 - Criteria for Safety-Related Electric Power Systems for Nuclear Power Plants

'g RG 1.52 - Design, Testing, and Maintenance Criteria for Post Accident-g Engineered-Safety-Feature Cleanup System Air Filtration and Adsorption Units of Light-Water-Cooled Nuclear Power Plants RG 1.78 - Assumptions for Evaluating the Habitability of a Nuclear Power

'I' Plant Control Room During a Postulated Hazardous Chemical Release 10

.I I

'I RG 1.95 - Protection of Nuclear Power Plant Control Room Operators Against an Accidental Chlorine Release Plant Technical Specifications The Limiting Condition of Operation and Surveillance Requirements are I

usually contained in the Plant Systems Section, 3/4.7.2 Main Control Room Environmental Control System (number and title vary among plants).

This technical specification applies to the two emergency HVAC trains that serve the control rooms, and it requires that at least one essential chiller be I

operable for 7 days.

If the second chiller becomes inoperable then there must be a Hot Shutdown within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and a Cold Shutdown within the next 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. CAUTION: The Plant Technical Specifications (PTS) are plant specific

'I and the above description is an example only. Other sections of the PTS apply to ESF pump rooms and equipment rooms. The few PTS reviewed did not provide-criteria about temperature or humidity limitations or surveillance requirements. The chillers are considered " attendant" equipment.

Nuclear Safety Classification The essential chillers are classified as Nuclear Safety Class 3 equipment. The equipment component regions listed below shall be designed and fabricated in accordance with the ASME Boiler & Pressure Code,Section III, I

Code Class 3.

An ASME "N-Stamp" is required, as specified in Paragraph NA 6254.1 of the ASME Boiler & Pressure Code, on the following item boundaries:

Evaporator Water Side I

Evaporator Refrigerant Shell Side Only Condenser Water Side Condenser Refrigerant Shell Side Only Oil Cooler Heat Exchanger Excluding 011 Piping and Valves All External Water Piping and Valves Associated with the Oil Cooler Seismic Reouirements The essential chillers are classified as Category I Seismic Equipment and they shall be designed to meet the applicable requirements.

The chiller I

and all its accessories (including thon remtely located from the chiller) shall be seismically qualified under the requirements of IEEE-344 by combination of analysis and testing. The chillers shall be designed to I

withstand seismic loading in accordance with the Uniform Building Code (UBC) for the Earthquake Zone Level at the chiller's geographic location.

l l

l l

StandaCdl l

The equipment shall comply with all state inspection rules and laws.

All nuclear vessels and components are designed, constructed, inspected, and tested in accordance with Section III of the ASME Boiler & Pressure Vessel Code, and the associated safety relief valves must be registered with the National Board, and so stamped.

11 I

p.,.

t The chiller and its accessories, including the control panel and its related components,.shall be qualified in accordance with IEEE-323, 334, 'and 344.

The materials, design and construction of the chiller and its accessories shall comply with, but not be limited to, the following standards:

l Anti-Friction Bearing Manufacturers Association (AFBMA)

American National Standards Institute (ANSI) Standards ANSI N18.2, N45.2.2, N5.12, B9.1, B16.5, B31.1, and B31.5 Air Conditioning and Refrigeration Institute (ARI)

ARI 550 - Centrifugal Water-Chilling Packages ARI 560 - Absorption Water-Chilling Packages ARI 590 - Reciprocating Water-Chilling Packages American Society of Heating, Refrigeration, and Air-Conditioning Engineers (ASHRAE)

ASHRAE 15 - Safety Codes ASHRAE 30 - Methods of Testing Liquid chilling Packages American Society of Mechanical Engineers (ASME)

-Boiler and Pressure Vessel Code Section'II - Materials SpecificationsSection III - Nuclear Power Components-Section IX - Welding and Brazing Qualifications American Society for. Testing and Materials (ASTM)

American Welding Society (AWS)

Institute of Electrical'and Electronics Engineers (IEEE) 279 - Criteria for Protection system for Nuclear Power Generating I

Stations.

308 - Criteria for Class IE Electric Systems for Nuclear Power Generating Stations I

323 - Standard for Qualifying Class IE Electric Equipment for Nuclear Power Generating Stations 334 - Standard for Type Tests of Continuous Duty Class IE Motors for

a Nuclear Power Generating Stations-g 344 - Guide for Seismic Qualification of Class-I Electric Equipment for Nuclear Power Generating Stations 383 - Standard for Type Tests of Class IE Electric Cables, Field Splices, and Connections for Nuclear Power Generating Stations 12 I

IL National Electric Code (NEC)

MG-1 Standard Publication for Motors and Generators (NEMA) f

- National Fire Protection Association (NFPA) Standard 90-A h

Occupational Safety and Health Administration-(OSHA) Standards Health Act Steel Structures Painting Council (SSPC) Standards SP-1, 3, 5, 6, and 10 Underwriters Laboratory (UL) Incorporated Standard UL-723 L,I.

g 4

I g

g I

I u

I o

I 13

I 4.0 CENTRIFUGAL CHILLER DESCRIPTION About 90% of the chillers found in the NPPs listed in Appendix A were I

centrifugal chillers, and most of them were driven by hermetic electric motors. Therefore, this study has focused on the hermetic centrifugal chill er..

A discussion of how a typical hermetic centrifugal chiller functions is provided in Appendix B.

Alternative chiller types are discussed briefly in Section 2.0, and they will be reviewed in more detail in the Phase II study.

4.1 CHILLER DESIGN A photograph of a currently marketed hermetic centrifugal chiller is shown in Figure 4.1.

It is quite similar to older chillers that are still in I

service in the NPPs. The newer chillers have advanced controls, and computer control is now available. Many improvements have been made in recent years; and the older chillers can be upgraded because manufacturers make many of the

=

new features available in retrofit kits.

The reference chiller shown in Figure 4.1 is a Carrier Corporation model.

For comparison purposes, a York International Corporation chiller is I

shown in Figure 4.2, and a The Trane Corporation chiller is pictured in Figure 4.3.

All three of these manufacturers share most of the NPP centrifugal chiller market.

A cross-sectional view with the refrigerant flow path of the reference chiller (Carrier) is illustrated in Figure 4.4.

The compressor cross-section view is shown in Figure 4.5, and a view of a purge unit is shown in Figure I

4.6.

Typical piping and wiring are illustrated in Figure 4.7.

Dimensions and layout requirements are given in Figure 4.8.

A liquid open centrifugal chiller is illustrated in Figure 4.9.

This figure shows the dimensional envelope changes compared to the liquid hermetic centrifugal chiller shown in Figure 4.8.

The open centrifugal chiller has a I

motor that is sealed external to the refrigerant system boundary and is exposed to the chiller room environment.

4.2 MATERIALS OF CONSTRUCTION Based upon information that was gathered from product literature (from the manufacturers), the typical materials used in the construction of chillers are listed below.

Cooler (Evaporator) - Shell-and-Tube

- Shell - Certified carbon steel plate

- Waterboxes - Certified carbon steel plate

- Division Plates - Steel plate I

- Tubes - 0.30 - 0.39 cm (0.75 - 1.00 in.) diameter externally finned seamless copper or copper 90/ nickel 10 tubing l

W i

LI

.n g-

~

$w4;g.

~*

s y,

N

l

~

M _.2:e E

L

x

~'

• g

'/

6 l

e

i I

l-7.

19DH.

L; i

l lI FIGURE 4.1.

Current Model of Liquid Hermetic Centrifugal Chiller Manufactured by the Carrier Corporation - Reference Design l

(Permission to use graphic is pending.)

i l

15

I

s I

4 jiiC( h'

.l l

)

se l

G l

E FIGURE 4.2.

Current Model of Liquid Hermetic Centrifugal Chiller Manufactured by the York International Corporation (Permission to use graphic is pending.)

1 i I

8

I g

LI FIGURE 4.3.

Current Model of Liquid Hermetic Centrifugal Chiller Manufactured by the Trane Corporation i

(Permission to use graphic is pending.)

16 l

I r

I I

I m,m w a i

hdh na0 TOR TRANSBdi$50s

,_sD AN W

vvw m" gy a wy j%b.

aun'uamt vm qiiiiiiii

{

nrrmaner uouto pf h{g, tP? '

g,m, - uwicev e

,a en

E

?,

Wg w w===

n wm

' z M W4lr d B :.:WS & l

?:th,d?T T.

^

'....'&WUsW 'ev'

^ ' Q ^ > 5? k'2 '.' Y*Y

=

i,_

.mm,,xmadge mme p@.. '-w,aws ;. " lw;m enc l

QTfkpg(ll

'r t'

2

-3 f

.=

a u.=

, - - - ~

.g gung 9

' M5M

%j. Urig ; &_

m me W

.I.

SON" 4 a.

me n i

")'E" smvis vatvt

'E W>txP 3

- s oc FW coima.

W 300 FW COWTPOL,;Ojyggy;lg y

\\

y3 +.,

ig"9s dM:yjjg+j*hk,;NINENbG I

ph~

f

$R W, ta i

4 r

y I

j

.o..-

3 js_mo v.i Et2NOGA!ZER SPMAY PIPE OMIFICC

.. s.

I smu.c mye i

FIGURE 4.4.

Reference Carrier Chiller Cross-Sectional View-

-j With Refrigerant flow Path I

(Permission to use graphic is pending.)

17 I

I

'I In-line impeller design g 9,,

e 3

In-line impeller design, with diaphragm j

-e

//

7 "rs between stages, allows for more fled 4

,3 s

bihty in compressor component selec-i.

L __ud tion, which results in first cost savings

-a p

U!

on other machine components. Also (Q '

p i; -k a

n3 j."

__ __ _ _,_h h

prOVideS higher head capabilities, pre-l

%-. L. n,-

f li'

'5

)

w

. 1-.. T ~

Vents uneven loading and aGows for

,p f

/

.routne, easy matntenance.

4 w g.. r - - - - b %

j\\

c,1 1

l l

&~ ~

ti

./

(;

)

LEGEND I

~

1 - Mme End hearme 8 - M.sh speed Journal peering I

e-2 - Geer Journal Beerms 9 - Frorn of Igel'er to Vo6uis Wsti l

jN y

3 - Dronng Geer Beereng la Haume 10 - epeiter Eye to (0 of heet Ring

~7M M 4 - Theust Cererence on Goa' 11 - Lawenm Behind wpeamr to Bearing mach sedel her Rg

}

6 - Peace Gest Journal Baerang 12 Lateyrem Behmd Trenamessaan i

19 0 s - Po.ca Geef Beating To Housing end Motor Shao 7 - Thrust Beerne 13 - End-hen Seanne Latrynnah I FIGURE 4.5. Reference Carrier Chiller Compressor Cross-Section (Permission to use graphic is pending.)

l

'I i a nuusul ( 4 jfaQjMi ;un f -.w ?,.. l e D Qkj Ug . f ni, l FIGURE 4.6. Reference Carrier Chiller Purge Unit (Permission to use graphic is pending.) t 1

. _ -. _.. ~.- -. __ = Ill 1 e i i l I ~ I w.m TO MAIN l ' DISCONNECT I t t t L L;7 8 l M-Y i e l rra j .:r g p i e,-[ l / l ~#7 %4..'.f;

s.,& "^'-

To < A.; Coou '".,.M ~.I,7 ' ' ' ~ I ~ 'N ' CODUNG MR }y Q[ 7' pp N -\\ 'N LOAD \\ <T i (, M ' ' , w ~~ ~ 5-N/ 'N, 'j.g g \\ s f., .,]; y' N a - a PIPING D QA-n.0w' '- /' \\ A~~ N COhrfROL WlRING g g j...- - m SWITCHES,, %.( N / s y I \\,-- - 3 N' \\ e; POWER wtRING - I g s ,. Y \\. '3 ,A ~ .~! 'M }< / g~ - x.. s - - \\/y s l \\ ' k, /( '( .y \\' ~. s p. I

~g x

\\- ^, \\..A s ,;s, t, ,A \\ Ng N. ' M N. ,^ ' .( f. i \\. N /' 'N s 'N, ' } /,\\ / '\\ \\ \\ -N j \\ N-f' \\ ,K, N i LEGEND NOTE S ( 1 Coahng Tower Fan Stener 1 Wiring and piping shown are for perseral point of-conriection only 1 2 - Condeaser Watef Pump Staner and are not intended to show netaels for a specific instattetton 3 - Coo:er Water Pump Starter Cen:f:ed field wiring and dimens6onal diagrams for specific 19 1 Series rnachines are ave,lable on request ,_p 1 5 - O<f Pump Stonei l 6 Fused D<sconnect for Oil Heater arrt The mosiat tech neg aes 7 - Ft. sed D'scovect for Purge System 4 A separate 115-voit fused power source for cont ols is required B - Fused Drscovert uniess compressor rnotor control is furnished wrth a transforrner 9 - Compressor Motor Terwnal Bos 5 Proede a separate fused 115-volt power source for oil heater and 10 - Compressor Motor Stone, ther ena sta t I 11 - Coo'er Water Pump 12 - Condenser Wein Pump I FIGURE 4.7. Reference Carrier Chiller Piping and Wiring Illustration (Permission to use graphic is pending.) i E

I i 1 w %, K'n~p svsfoe ano-ypg f m a ntucs =%' s D.- I ] (5t1 SERVOf Q- .I cd Asum:E Fon woroRs Y*stEl Vej nrrERIM'E U d ^" (E XT RE ME' f J DiMEPrSt0NB1 ~ l I-r'-s' C _M 4* on o.a,iP P / r, Assrw scv 4r4 R[segv&L CDh3ENSER ~ COOLE' -L-X Tuer pr*omL - l (OMR EhM 3$ 1.M _ \\ .gg )Q[? .-g hM, 4 FLDOR (DNT 15 ,'s y%.- - 6m.m> a y ?; l +-v n a. e 4. ieone,,, N !j [ C""3 gagERVICE mR \\NV of aaow raf mo ) win m gARANCE Aa ARO.MD Certif ed dienension drawmgs available on request UNISHELL DIMENSIONS (ft-in) (mun) NOZ2LE SIZE Dn.) I SIZES LengttF Width H5ght Cooler Passes Condensor Passes D 19DH A. B C 1 2 3 4 1 2 3 4 42,44,46 14-3-3/4 4362 37-1/4 1099 6-4-3/4 1948 3 1/ 6

994, 6

4 6 4 50 51 53. 14-3 3/4 4362 3-7-1/4 1099 6-10-1/2 2006' 3-3-1/8 994 8 6 6 8 6 4 1369 8- 01/2 2461 411/8 1248 8 6 6 6 10 s 6 6 61,63.65 14-3-3/4 4362 45-1/2 ' 1606 8-91/2 2440 49-1/8 1ebt ~ 10 8 8 6 10 8 6 6 ~5T 4-11 1/4 71.72.73 1433/4 4 76.77.78 1433/4 458' 2 - 4-11-1/4 1606 8-9-1/2 B00 ~ 4-9 1/8 1451 ~T2 s a 6 12 10 e s

• Length shown is chiller w'th nouki on dirve ernd only. For length with norxles at both ends, add 6-1/4 m (159 rnm)

"^ ^ SERVICE CLF.ARANCE FOR MOTORS (ft-inj i, 7 g.: .,c- .~ h-s, h.M" ~ DE SIGN CLEAR AN CE SlZE + CE NTE R (E l I s .,t VOLTAGES U neshell Cornpr W1or (ml imm) ' O~ . bo ' -- 42 thru 65 12inra 38 AA thru Af 60'.675' 50 thru 78 43 trwu 68 1 ~ 1 "= ~NN CB n ** 61 thru 78 72 thru 98 CD thru CO M ' M ^ I' ~ I f

• ^

50 thru 78 43 trwu 60 CA thru Ct. p 2400Si4160 -N ~ =* 61 thru 78 7 2 trwu 93 CD thru CO fE 1 =m p I I kJf fQ,Yh l 4@g{ Q ~ -[p: 'He seu Service access should be piovidad per ANSIStanderd B91, NFPA - e' 70 (NE C) and local safety codes Clear space adeguate for mapec. I tion, servicmg and ngomo of all rnejar cornponents of the ch>Iier is $,4.m mfLype@y.nt%, regawed. Selected component removal spaces. wah no aI6owance , _.s at!*_ for access or rigging are shown en pharvtom. DIMENSIONS (ft in.) 4tevn) SIZE. 19DH A B C D E F G I 3-10 3-8 O-4 0-4 D1 1/2 04 0 2-1/2 42 57 914 1118 102j 02 ' 38 102 84 ' 61'65 3 11 4-5 05 43 014/2 46 0+ 1/ 2 1994 1}!4 127 76 : 38 152 '38 47 5-1 0- 5 OL 3 01 0- 5 02 71-78 I 1397 1640 127 74 ' 25 J 127 " $0 -' 'See machme informat:ve piste. s FIGURE 4.8. Reference Carrier Chiller Dimensions and Layout Requirements (Permission to use graphic is pending.) 20 I +

.~. I ~ Dimensions O'4?,e4 (152 mm)' E I ~ Ll' C f (813 nun) Wz' s~ i l l 1r t I (3%1 mm) / i E- / / (610 mm) ,s'- E. TypicalIwJation As.embree.(Wittwut Spring Mount.) o 0, I we awr' ' s.N'- %g - 1 'I g#. g , ' /j._ jeyg as s.=e w eenac.e,w e== um Alkie F4" t.10 evn) nw*wsn verscas and E y f _sWele. e Co,efed emeneen erewmg evadsten on eguen 3 g, im.es NOTES %h[ g"g" I* j $I I .e

e.. tweed.ee %. hat i.

t muun be uned be 3. eee I' 1 DitIEM.40N. 9001.11 2E tm.) .ct. Widh* A indgh. HelgPd C Ceese, Pasmes Cenemeer Petees Sh num set see e m. eue 1 3 4 1 2 3 e 1M I 42.4 e. 18 4 .3 3-. 1,1 .5 ,95. 4 i .3 u .,i rio. =gif u ,m 71, FL 73 14-11 464 50 1524 . 10 2 92 10 10 . I m r,. .4 m. w e . e e, ,,,e e. ~ en,,. in - e..e e n m.i -> g: FIGURE 4.9. Current Model of Liquid Open Centrifugal Chiller Manufactured by the Carrier Corporation (shown to contrast with hermetic centrifugal-chiller in Figure 4.1) (Permission to use graphic is pending.) 21 I T g 4 v. -+,, ,y u-.e..g ,-4 y.

~ I - Tube Sheets - Certified carbon steel plate sometimes clad with copper / nickel alloy sheet - Tube Support Sheets - Steel plate Condenser - Shell-and-Tube E-Materials the same as for Cooler (Evaporator) Compressor - Drive Shaft - Heat treated alloy steel - Impeller - High strength aluminum casting - Casing - Close-grained cast iron - Labyrinth Seals - Nonferrous metal ~ - Bearings - Aluminum alloy, bronze or babbitt - Pre-rotation Vanes - Manganese bronze - Shaft Seal - Carbon ring with elastomer 0-ring Motor Components typical of squirrel cage induction-type motors with windings that are sealed hermetically with refrigerant atmosphere resistant' insulation Miscellaneous - Rings - Viton, synthetic rubber, BUNA-N, neoprene - V-Ring Sets - Molded teflon - Gauges - Steel case, bronze or brass bourdon tube, monel'or stainless steel movement, chrome planted steel or _ brass face ring, and glass crystal - Oil Cooler - Steel'shell, admiralty tubes, cast iron bonnets, and steel tube sheets and ~ cross baffles Isolation Pads - Molded neoprene .I I 22 I

5.0 OPERATING EXPERIENCE DATABASE EVALUATION The results of evaluating chiller operating experience from databases -I traditionally reviewed in NPAR studies are provided in this section of the report. Some of the data evaluated included information on alternative types to centrifugal chillers. 5.1 LICENSEE EVENT REPORTS (LERs) DATABASE A Summary of the Chiller LERs is given in Appendix C. The summary covers 1981 through 1991. The LERs were compiled from the Sequence Coding and Search Systems (SCSS), the Nuclear Documentation System (NUDOCS/AD), and Regulatory Information Distribution System (RIDS) databases. Some of these I items (11) are common to the Nuclear Power Experience (NPE) database items discussed later. The results of the evaluation of chiller related failures are summarized in Table 5.1. TABLE 5.1. Summary of Chiller Failures in the LER Database Failure Descriotion Number of Occurrences Water Leak 1 I HX Tube Fouling 1 HX Tube Plugging 1 Inadequate Cooling Water 4 Service Water Component Failure 1 Lubrication Oil Leak 3 Refrigerant Leak 5 Refrigerant Plugging 2 Open Motor Bearing Failure 1 Mechanical Component Failure 2 Mechanical Control Component Failure 7 -I_ Electrical / Mechanical Control. Component Failure 5 Electrical Control Component Failure 16 Electrical Component Failure 7-Motor Starter Failure 1 .I No Failure Cause Determined 7~ Total Failures 64 (*) (a) Some of the LERs listed multiple failures The largest number of failures (16) were with electrical control = ~ component failures. Mechanical and electrical control component failures (28) represented about 44% of the total failures. Electrical related failures- (38) occurred about twice as often as those failures which were believed to-be ~ mechanical related (18). Of the listed failures there were at least 5 non-aging-related failures. -Three were failures due to human error,' and one each

I-was due to a manufacturing defect and use of a seal made of the wrong material. The balance of the failures were due to a combination of age-1

r_ y I-s i and/or non-age-related degradation. Insufficient detail was available to determine.the quantity of just the age-related failures. Many LERs which reported chiller trips were not included because the events were caused by condenser cooling water system failures (e.g., filter, strainer, pump, and valve failures; plugging, air injection, undersize, etc. of cooling water piping). I Of the failures that stopped the chiller, four occurred outside the chiller boundary. Three of the failures were in the cooling water. supply system and one was at the remote motor control center. 5.2 NUCLEAR POWER EXPERIENCE (NPE) DATABASE The information from the NPE Database search is provided in Appendix D of this report. The information covers 1978 through 1990. The chiller failures are summarized in Table 5.2. TABLE 5.2. Summary of Chiller Failures in the NPE Database-Failure Descriotion Number of Occurrences Water Leak 1 HX Tube Fouling 1 l HX Tube Plugging 0 Inadequate Cooling Water Flow 4 Service Water Component Failure 0 I Inadequate Chilled Water Flow 6 Lubrication Oil Leak I Lubrication Oil. Plugging 1 Lubrication Oil Excessive to Evaporator 2 I~ Refrigerant Leak -7 Refrigerant Plugging 0 Open Motor Bearing Failure 0 I, Loose Parts Damage 4 Mechanical Component Failure 5 Mechanical Control Component Failure 4 Electrical / Mechanical Control Component Failure 7 ^I. Electrical Control Component Failure 8 Electrical Component Failure 9 Spurious Electrical Parameter 3 l. Thermostat Out of Calibration 2 Switch or Valve Out of ' Adjustment 4 Motor Starter Failure 0 .E-Low Environmental Temperature 1 W No' Failure Cause Stated 3 Total Failures 73 (*) k (a) Some of the events listed multiple' failures. 24-I

!I-The largest number of failures (9) again occurred with electrical component failures. Mechanical and electrical control component failures (19) represented about 26% of the total failures. Electrical related failures (24) I occurred about twice as often as those failures which were believed to be mechanical related (13), The total number of failures listed in Table 5.2 were 73, and all were partially or totally age-related. There were at least 12 non-aging-related failures which were not listed in Table 5.2 because the event description was too general. Three were g failures due to human error, four were due to inadequate procedures, four were x - 3 due to inadequate cooling capacity (facility design), and one was due to inadequate refrigeration load (equipment and facility design). ~ 5.3 IN-PLANT RELIABILITY DATA SYSTEM (IPRDS) DATABASE A list of the chiller failures reported in the IPRDS Database.is given ) in Appendix E of this report. This information is from a single nuclear power

a plant called Plant A.

The plant essential chillers are identified as Chillers IA and IB. This data covers about 5.5 years of operation at the plant. The failure data for the essential chillers are summarized -in Table 5.3. TABLE 5.3. Summary of Plant A Essential Chiller Failures Number of Occurrences Failure Descriotion Chiller IA Chiller 1B Total Water Leak 1 4 5 HX Tube Leak 0 1 1 HX Tube Fouling 4 0 4 I HX Tube Plugging 2 2 4 Service Water System Failure 0 1 1 Chilled Water System Failure 1 0 1 i 3-Lubrication Oil Leak 12 8 20 . 5 Lubrication Oil Plugging 5 2 7 Refrigerant Leak 7 3 10 Mechanical Component Failure 1 2 3 I Mechanical Control Component Failure 1 1 2 Elect./ Mech. Control Component Failure 6 4 10 Electrical Control Component Failure 14 11 25 j Electrical Component Failure 6 7 13 No Failure Cause Determined 1 2 3 Total Failures 61 48 109.

s The category showing the most failures for Plant A was for electrical g'

control component failures (25). That was also the largest failure category for the LER data in Table 5.1. The next largest failure category was-lubrication oil' leaks (20), which with lubrication oil plugging (7) made up ' I' about 25% of the total failures. The balance between mechanical type failures and electrical failures was about the same. Of the failures shown in Table 25 I

I 5.3, the non-age-related failures-totaled four. Three were due to human error and one was due to manufacturing error. The rest of the failures were a combination of aging and non-aging failures with insufficient detail available I for further analysis. 5.4 NUCLEAR PLANT RELIABILITY DATA SYSTEM (NPRDS) DATABASE No chiller failure data were found in the NPRDS database. I I I I I I I I I I I I I l 26 i I.

6.0 OTHER OPERATING EXPERIENCE '6.1 PACIFIC NORTHWEST LABORATORY (PNL) EXPERIENCE A total of seven liquid hermetic centrifugal chillers are used to cool PNL HVAC facilities. Five of the chillers are cooled by river water from an evaporation pond and two are cooled by well water from cooling towers..The chillers range in size from 185-to 450-ton capacity. Some of the chillers serve laboratories where temperature control is critical. To ensure the reliability of the chillers, PNL contracted with . experienced service companies that perform major overhauls and tube cleaning activities. A maintenance program was established about 12 years ago to improve maintenance practices and reduce equipment neglect. The service company selected was considered one of the best available. They have used the same service personnel, so the history of the chillers can be monitored, problems can be anticipated, and service life improved. The PNL maintenance staff has been trained to monitor the chillers daily and to make all the minor repairs. Only the service company does major repairs inside the refrigerant boundary. Major overhauls are performed on the schedule ~ recommended by the manufacturers. Because of good routine maintenance practices and equipment-monitoring, it appears that the time between overhauls can be increased. The condenser tubes are cleaned and eddy current tested annually by specialty service companies. The condenser performance has improved and little degradation of tubing has been observed. Only one major failure in one machine has caused unscheduled downtime. The failure occurred in a 1.3 cm (0.5 inch) steel pipe that broke due to. vibration fatigue. The root cause was a lack of adequate pipe support. h During overha'uls the main tasks are to inspect the components and replace or 4 repair them if needed. The only major repair required was to rebuild the labyrinth seal and impeller tips where some unexpected wear occurred. The j seals, gaskets, filters, etc., are routinely replaced during overhauls. The entire refrigerant system is scrupulously cleaned to assure all dirt, moisture, etc., are removed before the system is re-sealed. Overhauls are recommended at either 3-or 10-year _ intervals by the major centrifugal chiller ' manufacturers. Some of the machines have been upgraded with.the more modern purging units to remove moisture, non-condensable gases, etc., from the refrigerant system. .The equipment temperatures, pressures, and other indicated operating parameters are monitored daily. Samples of the lubrication oil are routinely analyzed. Using the la_mg well-trained maintenance and service company. staff has been an asset in achieving an excellent performance record for the chillers. Conscientious. management and supervision of chiller _ maintenance has i . resulted in an excellent performance record for the machines. 6.2 WESTINGHOUSE HANFORD COMPANY EXPERIENCE The 337 Building has two 250-ton liquid hermetic centrifugal chillers which are cooled by treated river water from a cooling tower. The condenser 27 i

I cooling water has not caused problems. The chilled water system uses an ethylene glycol / water mixture which has not caused problems either. The main problems have been with electrical and mechanical control components damaged by vibration and overheating of components in the motor control center cabinet. Major maintenance has been difficult in the past I because plant forces are used. Human errors have been made which caused subsequent failures. Recently, increased staff training has reduced problems and failures. The cooling tower capacity for the chillers is undersized. This is a continuing difficult situation for the management of chiller control. There are times when compressor surging is prevalent. The Fast Flux Test Facility (FFTF) Reactor has eight 400-ton chillers that serve a variety of service functions. The chillers are hermetic centrifugal type. Both the chilled water and cooling water systems are I closed, and they use glycol / water. There has been virtually no corrosion of the HX tubes or tube fouling. The original water came from on-site wells. Except for one major failure, due to human error when one of the chillers was new, there have been no major failures. A main bearing near failure was discovered during an overhaul. The time between overhauls was I reduced from 17,000 hours to 8,000 hours, and no major problems have occurred since then. The manufacturer has recommended that the time be 3,000 hours, but 8,000 hours appears satisfactory. The overhauls are performed by a regional service company, and they have done an excellent job. FFTF I management is satisfied knwing full-time. overhaul experts are taking care of their equipment, which results in more reliable operations. FFTF maintenance personnel are well trained and have good procedures that they follow for routine and minor maintenance work. Most component failures are caused by vibration. A lot of the failures are considered a nuisance. Indicator lamp bulbs and terminal and wire I connector damage are examples of vibration induced failures. They estimate that about a third of the failures are electrical and the balance are mechanical. Repeated vibration damage to items like timers, cam switches, and I relays could be reduced if the control cabinets were updated to the state-of-the-art. I Most of the vibration occurs because the chillers are often operating at partial or low loads. Vibration problems become more severe when operating below 25% capacity. Even though the equipment is rated for 10% capacity, operation at this level becomes intolerable due to changing conditions. I Surging becomes prevalent at the lower capacities. Ideally, FFTF would like to run the chillers continuously at full capacity, because they run smoother and do not have as many component failures. 6.3 REGIONAL SERVICE COMPANY EXPERIENCE { An expert consultant, Tom Camp of Landis & Gyr Inc., provided insights 'R into failure and failure causes based upon his experience. He has spent about 28 I l l

I 25 years trouble shooting, overhauling, and doing major repairs on centrifugal chillers while working for service companies. He has serviced non-nuclear-related commercial chillers throughout the Pacific Northwest. Since he _I-inaugurated servicing the PNL chillers, they have improved and had outstanding reliability. He helped train PNL staff to care for the chillers. I Based upon his experience, he made the estimates and observations listed below. The general causes for chillers to completely fail are as follows: Failure Cause % Failures Comments Design 1% Poor use of design performance history Manufacturing 3% Poor replacement parts, packaging, dwgs. Installation 11% Lack of coordination and instruction I Components Aging Failure 5% Friction, heat, non-serviceable component Lack of Monitoring & Maint. 60% Poor O&M management and apathy Human Error (0&M) 15% Carelessness and un-cleanliness Other 5% Mis-application The greatest cause of failure is lack of monitoring and inadequate routine maintenance. Monitoring and maintenance steps that will significantly help reduce the number of failures are as follows: Control the water quality supplied to the condenser and evaporator. Routinely analyze lubrication oil to assure correct chemistry. Routinely analyze refrigerant to assure correct chemistry /need based l upon results of lubrication oil ar.alysis. Eddy current test nondestructive testing (NDT) the tubes to monitor corrosion, etc. Periodically examine tubes; clean if necessary on a schedule. Periodically perform vibration analysis using some equipment. Heat scan the electrical components with infrared temperature sensing instruments. Visually inspect and record gauge readings on a daily basis. Record daily readings on trending charts. Analyze the trend and take immediate corrective action if the trend becomes adverse. Perform all routine maintenance and service per manufactures instructions. I. Annually service and test components to determine / assure reliability. Field strip motor control and starter contacts, change oil and filters, I I

I service purge / dehydrator unit, change drier, run operation and safety-control tests, inspect HX tubes for fouling and corrosion, etc. I f. Periodically (3 to 10 years) overhaul and inspect all wearing parts (using an interval based on the shortest life of the materials) within the chiller (typically the o-rings, gaskets, and carbon seals). In all cases,. cleanliness and care are most important. 3 The components which most commonly fail, primarily due to age-related !g' degradation, are Pressure switches Temperature switches Relays Flow Switches Gaskets and 0-rings (External Leaks). The components which less commonly fail, primarily due to inadequate lubrication, chemical attack, maintenance, and age, are the following: Bearings Tubes ~ Guide vane Oil relief valve Oil pump Seals l Expansion device Float valves Agitator Minimum head control Purge unit Motor. control center g 1 30 .I. I

I The following aging stressors and mechanisms are encountered by chillers: Vibration (Normal and Excessive) Excessive Heat Excessive Pressure Moisture Dirt and contamination Non-condensable gases (air, etc.) Corrosion Tube freeze-up Mineral contamination Biological attack and growth Flow erosion External environment (temperature, humidity,. fumes, etc.), especially at damaged flanges, joints, and electrical control and wiring Friction and wear Thermal cycling Mis-alignment Start-up' torque Frequent starting / stopping. 6.4 COOPERATING UTILITY EXPERIENCf ( Direct contact was made with one NPP to tour the plant and discuss chiller performance..A copy of the maintenance request data system was-. received for two non-essential chillers. The essential' chillers are used only - for emergency situati. s. The only major problem incurred by the essential

I

chillers was that one chiller had its tubes-freeze up due to human error. The plant is. relatively new and only about 4 years of operating experience were available. The summary of work requests for the non-essential chillers is-presented .g in Appendix F of this report. Most of the activity was related to:-start-up and up-grade work. The following items were most notable: 31-J'

Thirteen tubes in the condenser and evaporator of Chiller IA had to be replaced. The tube holes in the tube sheets had to be repaired. Crevice corrosion normally caused by excess moisture and subsequent.

I:

vibration failure is suspected. Both units had the same manufacturing defect. The lubrication oil pump I solenoid valves were installed backwards. The manufacturer determined that all 22 of the units for that model had the same problem. Both valves had to be replaced ultimately. Earlier oil jet pump problems were probably related to the valve being 180 degrees out of phase. A new mist eliminator had to be installed in Chiller IA, which was probably related to excess moisture in the refrigerant. I. 6.5 EXPERIENCE FROM LITERATURE REVIEWS I Examples of age-related failures /causes that occur in chillers were compiled from a literature review. Surprisingly, the discussion of aging and failures in the literature was sparse for such a large industry. There was a natural reluctance of the industry to document and compile failure /cause data. The literature search was performed by the PNL Technical Library. The list of major types of failures /causes is outlined below. Maior Ace-Related-Failures /Causes Excessive moisture in the refrigerant can cause many problems in the I chiller (Traver 1976; ASHRAE 1990 Refrigeration Handbook). When the amount of moisture exceeds the refrigerant saturation level (only a few ounces in 1000 pounds of refrigerant), the free. water reacts with the refrigerant to' form hydrochloric and hydrofluoric acid. The acid attacks crevices between the I: tubes and tube sheet. Combined with vibration of the tubes, especially from boiling refrigerant in the evaporator, the tubes widen the annulus and ultimately fail, allowing water entry to shut down the chiller and expose the I entire system to water. Other degradation which occurs as a result of the - acid attack includes the following: Acid contamination of the lubrication oil causes attack of'the. bearing I surfaces. The. compressor inlet guide vane assembly can corrode and bind. Motor failure can result from insulation breakdown in hermetic units. The purge float valve can get stuck due to bearing and pivot corrosion. The condenser and economizer float valves 'can similarly fail. R Shell scaling can cause clogging between tube fins, between tubes, and in the mist eliminators. Subsequently, the scale hardens to restrict heat transfer and flow of the refrigerant. 32 i

I g' Copper chloride deposits on upper tubes are caused by the s wetting /unwetting process. These deposits reduce heat transfer and have hygroscopic properties that make removal of water difficult. 'I Tube fouling and corrosion can cause eventual chiller shutdown due to reduced heat transfer or tube failure (Banta 1974; Leitner 1980; Blake 1977; Alger 1977; Starner 1976). Tube clogging can occur if the condenser water is not filtered, treated, and controlled at the cooling tower or source (Barber 1983). Non-condensable gases, such as air, get in the machine and raise the

a condenser pressure. This, in turn, raises the compressor's load and requires J-more horse power (Barber 1983).

In addition, air can accumulate at the top of the condenser and combine with the refrigerant to drastically reduce heat transfer (Webb 1986; ASHRAE 1989 Fundamentals Handbook). Vibration can ultimately cause seals, gaskets, pipe joints, and fittings-to fail and allow leakage of the refrigerant. Moisture and air can also enter the previously sealed system by the same route (Esslinger 1988; ASHRAE 1991 Applications Handbook). The complete American Nuclear Society (ANS) Transactions Summary I (Christie 1992) of a paper presented in June 1992, is' included in Appendix G of this report. The' plant reliability analysis indicated that safety-related chillers fail three times as often as non-safety-related chillers at the River g-Bend nuclear power plant. The authors felt that the difference-in.reliabi_lity 3 is due to the more stringent control requirements imposed on the safety-related chillers. The information needs to be examined more closely. l NRC Notice 85-89 was addressed primarily at the potential loss of solid-state instrumentation following failure of control room cooling. The incident resulted in numerous spurious alarms. Previously the same plant had I-experienced similar behavior and numerous component failures and degradation due to high temperatures in control cabinets. The licensee had previously reported that their chillers develop oil level problems when loaded at less l than full capacity..The heat load calculated during plant design was too large compared to the actual heat load resulting in oversized chillers. The question "When does the final chiller failure occur?" is not an easy .l' one to answer because there are many variables to consider. An extensive survey of building owners and managers was conducted (Akalin 1978). The results ' indicate that chillers usually have a life of.-20 to 30 years with a 'E mean value of.23 years. The ASHRAE Handbook estimates the service' life of .W. centrifugal chillers at 23 years, but practical use for 30 to 40 years has-been realized when the equipment is properly maintained (Calm 1992). The PNL' consultant indicated that the major components of a chiller will last well 'I; beyond 40 years if they are properly cared for and maintained. Chillers up to 60 years old are in continuous use today. Most chillers fail and are replaced due to a. lack of maintenance and monitoring. Other causes for replacement : g (obsolescence) of chillers are 33 1

I Change'of heat load (usually growth)

Energy efficiency improvements Incompatibility with new refrigerants (Result of new regulations) Efficiency loss - Design of components - Aggressive nature of new refrigerants 'g.' . Centrifugal chillers have motors that are not designed to be turned on 3 and off frequently. Rapid cycling will lead to motor and starter failure.. The only safe way to limit demand for a centrifugal chiller is by modulating. the compressor's pre-rotation vanes, which control the capacity of the chiller. 'When the modulation is done, it is critical that it be done gradually..If not, surging of the compressor can occur, resulting in' serious-damage (Gorzelnik 1977). Prolonged operation in a surging mode.is likely to

3 damage the entire chiller, as well as the compressor.

Surging loads and E-unloads.the motor about every 2 seconds so that the motor current varies markedly (Ball 1987). Surging deteriorates performance and heavily stresses the thrust bearings. Surging is most likely.to occur at.the lower end of the. I chiller capacity range. -Chiller manufacturers claim that their units can-unload down to 10% of design tons, but one must remember that low load operation is conditional upon~ having lower condenser temperatures (Harmon 1991). I I lI I I I I g

I LI

f f 7.0 OPERATING EXPERIENCE

SUMMARY

AND DISCUSSION Review of the databases and literature in Sections 5.0 and 6.0 indicated -I' general information on chiller failures experienced during plant operations. Details were limited and difficult to analyze from strictly an aging standpoint. Also, not all of the chiller-related LERs, LCOs, and chiller I. failures have been found and included in the results of this study. For example, consider the numerous failures that occurred in the single Plant A. Most of those failures caused an essential chiller to trip. But few, if any, of the Plant A failures are contained in the LER or NPE databases. I: Considerably more time than a Phase I study would be required to get comprehensive failure data for each plant and consequently all of the plants. More specific information from additional plants will be sought for detailed aging analyses in the Phase II portion of the study. The information shown in Figure 7.1 summarizes the quantities.and .. I fail're areas from the LER and NPE Databases. Duplicate failures were removed for chis summary. About 11% of the failures were partially caused by flow - rate variations in the cooling and chilled water systems' and' partially by the I'. chiller condition (e.g., chiller fouling, load and capacity limitations, entrance strainers, etc.). Condenser / evaporator failures were only about 3% because most of the age degradation occurs gradually, maintenance access is usually easier, and it is handled during scheduled downtime. 'The I refrigerant / lubrication oil system-related failures accounted for about 15% of the failures. About 17% of the failures were mechanical and mechanical control related. Electrical / mechanical control components caused about 9% of the failures. Electrical and. electrical control components made up about 30% I of the failures. His-adjustment and mis-calibration resulted in approximately. 8% of the failures, and the 7% balance of failures was unknown. 'Nearly half of the failures were related to control components. I Using the same failure databases, an attempt was made to determine the degree to which failures were age-related. The aging versus nonaging failures are illustrated in Figure 7.2. About 81% of the failures were at least partially related to aging. More detailed information would be needed to segregate the failures which were primarily or solely age-related. About: 12% of the failures were primarily due to design, manufacturing, installation, I procedure, and human errors. The 7% balance of failures was unknown or unassignable. -l All of the failures discussed above caused chiller trips and most of the failures caused LC0 situations because one or both essential chillers were-inoperable. Both chillers were inoperable 25 times and resulted in -E implementation of shutdown procedures. The LCOs were invoked for control '5-rooms, engineered safety features (ESF) equipment rooms, and-containment. At least five times the reactor power _was reduced, and at least two plants had to. be shut-down. The exact number of LCOs, power reductions,'and plant shutdowns- 'I-that resulted from failed chillers is not known because'of the limited information available to review. As demonstrated in Appendix F, some of the. utilities are concerned about the LC0 situation due to the unreliability and complexity of essential chiller systems. I

I Failure Ares j-Failure Quantity l 0 10 15 20 25 ) I I I Coo 41ng Water System (6.3%) m i i Chilled Water System (4.8%) M Condenser / Evaporator (3.2%) M Retrigerant (10.3%) Lutocation 00 (4.8%) Mechanical (8.7%) i i Mechanical Control (7.9%) ~ Doctrical/ Mechanical Control de 7%) Doctr6 cal Control (17.5%) 1 ( 6 i Decincal(12.7%) Calibratiork Adjustment (7.9%) l No Cause Given (7.1%) l I FIGURE 7.1. Sum 2ry of Chiller Failures (LER and NPE Databases) I 6.5% Unknown I-12.3% Nonaging Related

I I

I 81.2% Aging Related (at least partially)

l FIGURE 7.2.

Aging Versus Nonaging Related Chiller Failures 36 . I. I

I; g The essential control room HVAC systems have increased complexity due to more interfacing systems than just the chillers. Numerous LCOs occur due to 3-monitor / automatic actuation systems; e.g., radiation monitors, combustible' gas 3 detectors, chlorine detectors, loss of power, filter monitors, etc. There are many instances in which the control room HVAC system was erroneously switched to the emergency mode, and spurious detector faults were a major cause. Also, some control room LCOs are caused by failures in the chilled water system other than chillers (pumps, valves, piping, expansion tank, etc.). I -One step that might help to reduce the occurrence of LCOs due to chillers, is to use a chill / ice storage system with a self-contained chiller that would provide 12 to 24 hours of extra buffer time before entering a limiting condition of operation. The stored ice will provide a passive system I for backup cooling. Numerous designs are available~ to provide such storage and additional backup chiller capability. The equipment could be located outside the control building. The backup chiller could use air cooling rather I. than water cooling. The overall design, complexity, reliability, and practicality of such an additional system would have to be carefully reviewed for each plant. These systems have been employed primarily to reduce peak refrigeration power consumption in commercial buildings. .I. The review information indicated that it is a concern to prevent serious degradation of equipment in the control rooms and ESF rooms due to excessive

I ambient room temperatures. One plant had a maximum limit of 25'C (77*F) for the control room temperature. Another plant had a limit up to 49'C (120*F).

There is concern about high temperaturas inside electronic cabinets, which can I-cause spurious reading, alarms, etc. that cause difficulty in controlling the plant. Temperatures' inside cabinets are much higher than t% ambient room temperature. A cursory attempt to find data on the-aging-degr dation for g-various levels of temperatures, humidities, and vibration on electronic g components was not successful. Further research in this area is recommended, but will not be pursued because this research is outside the scope of the~ chiller aging study. I The higher room ambient temperatures also cause discomfort for the personnel operating the reactor. In general, the comfort range is between 25% L3-and 65% relative humidity and 22 to 26 C (72 to 79 F) temperature. An 3- . operator's tracking skills, vigilance, and sustained-attention become very sensitive with time when the tenperature exceeds 30*C (86 F). Operators should not be exposed to temperatures above 35'C (95 F) for a period of more f than I hour. Very little information was found about human factors temperature and humidity criteria for control room operators. It appears that more research should be performed to determine the effects of high -E . temperatures upon personnel. Research in this area is also beyond the scope E of the chiller study. I I tI I;-

I

8.0 CONCLUSION

S Based upon this study, it is apparent that essential chillers are I important to cool the control room and other essential equipment rooms. Chillers are integral equipment currently being addressed in regulatory issues of concern, which include Generic Safety Issue 143 and Generic Letter 89-13. I The cooling is needed to prevent degradation and failure of safety-related equipment, to protect safety personnel, and to prevent or mitigate events and accidents. Control of temperature and humidity in these rooms is very important. The chillers used in the nuclear power plants are essentially the same as the ones used in other commercial and industrial applications. The I chillers are a relatively complex piece of equipment because of all the thermal and flow balances that need to be maintained. The essential safety-related chillers have more stringent standards and codes to meet. The basic 3 equipment must meet seismic requirements which require some minor 5 modifications to the components, structure, support base, and anchoring. The essential chillers have interfacing systems, often with complex interlocking controls. The analysis of chiller interfacing systems cannot be made I generically because the systems vary from plant-to-plant. Due to regulations, chillers need to be closely monitored and carefully operated and maintained. The essential chillers need to be afforded special care so they can be reliable and fulfill their safety role. The review of operating experience indicated that chillers experience aging degradation and failures. The primary aging factors to be concerned I about with chillers include vibration, excessive temperatures and pressures, thermal cycling, chemical attack, and poor quality cooling water. Aging is accelerated by moisture, non-condensable gases (e.g., air), and other - I contamination within the refrigerant containment system. Excessive start /stop cycling and under-loading of chillers cause premature aging. Aging is also accelerated by corrosion and fouling of the condenser and evaporator tubes. I The principal cause of chiller failures is lack of monitoring. Lack of performing scheduled maintenance and human errors also contribute to the failures. Failures due to design and manufacturing discrepancies usually occur during the original start-up, shakedown, or first year of operation for a particular new chiller model. In the NPP data that was reviewed, the largest number of failures were I related to electrical control component failures. Both electrical and mechanical control component failures represented almost half of the total failures. The lubrication oil system also had a relatively high failure rate. Most of the failures were at least partially age-related. Non-aging-related I' Lack of monitoring is suspected to be the greatest contributor to both age-failures were a smaller rumber and were primarily the result of human error. and/or non-age-related failures. I To minimize and eliminate most of the failures, the operators of chillers need to carefully follow stringent procedures and monitor equipment. .I Equipment performance must be recorded and trended on each shift or on a daily basis. The routine maintenance staff must be well-trained and careful. Major 38 .I I.

I overhaul and maintenance that requires entering the freca containment region must be performed by careful, well-trained, and experienced technicians. A small' amount of contamination or a damaged or misaligned part can cause major problems during operation of a chiller. It is crucial at all times to keep equipment internals very clean and prevent the leakage of water, air, and other contaminants into the sealed refrigerant containment system. Periodic operation on a weekly or monthly basis is necessary to remove moisture and non-condensable gases which gradually build up inside the g chiller. Just a few hours of operation will help, espet ially if. the chiller 3 is required to operate as an emergency standby unit. If multiple chillers are available, alternate the chillers and balance the huurs of use. ' Operate the chiller as close to 100% capacity as practical to minimize aging. Usually chillers are replaced due to lack of good monitoring and maintenance. In-depth analysis of aging and nonaging failures.will require close _E cooperation between the chiller industry, utilities, regulatory agencies, and 5 the researcher during.the Phase II study. During the Phase I study it was difficult to obtain the detailed information that was needed to perform in-depth analyses of chiller aging. I I. I I I I 39 I

9.0 RECOMMENDATIONS The Phase-I study determined that chillers have an important role in NPP ' safety. _ Chillers have been contributors to a number of serious safety events. where plants had to be degraded or shut down. Some plant operators are concerned about a higher number of failures in the essential chillers than j-non-essential chillers. The NRC is also concerned. The operating experience reviewed thus far indicates that chillers degrade and fail as a result of. aging and other factors. Therefore, it is recommended that a full-scale NPAR Phase II aging study be performed. In addition, based upon the regulatory safety documentation reviewed during the course of the study, the following recommendations are given: I The aging degradation effects on electrical, electronic, and computer components housed in cabinets, due to the excessive _ temperatures, <g humidity, and vibration expected in the control room, need to be -E evaluated. Actual temperature checks should be made and' extrapolated to the maximum temperature expected. Also, component exposure to condensation during rapid cooldown of the control room should be I evaluated. Requiring transient thermal calculations for safety-related equipment I- . rooms to determine heat-up rates following a loss of room cooling should be considered. _ There should be a follow-up with actual test measurements in the room and inside cabinets. Use of a remote modern HVAC ice storage unii to provide buffer cooling-storage should be considered. An additional 12 to 24 hours ~of passive cooling capacity would help relieve the burden of plant derating and prevent exceeding the Limiting Conditions of Operation (LCO)' time. In the case of events or accidents where off-site power is not lost, an additional remote _ chiller could be on line to keep the ' ice supply 'E replenished. This may improve the' plant reliability and safety. A-E cost / benefit study would be needed to justify serious consideration for a chill storage' system. Addressing temperature and humidity limitations in safety-related room requirements and specifications should be considered. Human factors' limitations should 'also _ be considered along with the impacts on aging - and reliability of the safety equipment. "l I

Il 40 g.

f

10.0 REFERENCES

Akalin, M. T. 1978. " Maintenance Cost Survey."' ASHRAE Journal, October 1978, pp. 40-44. Alger, J. 1977. " Treat Your Cooling Water To Cut Energy Consumption and 'E Increase Production Output." Plastics Design & Processing, April 1977, pp. -E. 59-63. ASHRAE. 1991. ASHRAE Acolications Handbook. American Society of Heating, Refrigeration, and Air Conditioning Engineers,-Inc., Atlanta, Georgia. ASHRAE. 1989. ASHRAE Fundamentals Handbook. American Society of Heating, Refrigeration, and Air Conditioning Engineers, Inc., Atlanta, Georgia. ASHRAE. 1990. ASHRAE Refriceration Handbook. American Society of Heating, Refrigeration, and Air Conditioning Engineers, Inc., Atlanta, Georgia. Ball, J.1987. "A Microprocessor Chiller Controller." Australian Refrigeration, Air Conditioning and Heating, April 1987, pp. 36-43. Banta, V. E. 1974. " Continuous Cleaning Ups Chiller Performance." Power, June 1974, pp. 76-78. Barber, J. 1983. "How to Improve Efficiency in Centrifugal Chillers." Energy User News, March 7,1983, Fairchild Business Newspaper Publishing, pp. 8-10. l Blahnik, D. E. September 1991. NPAR Pre-Phase I Chiller Aoina Study - Summary of Results and Recommendations. Letter Report prepared by Pacific Northwest Laboratory for the Nuclear Regulatory Commission, Washington, D.C. Blake, R. T. 1977. " Correct Water Treatment Can Save Energy.." Building Systems Design, April /May 1977, pp. 49-52. Calm, J. M. 1992. " Alternative Refrigerants: Challenges, Opportunities." Heating / Piping / Air Conditioning, May 1992, Penton Publication,' pp 38-48. Clark, E. M. 1991. "Retrofitting Existing Chillers with Alternative Refrigerants." ASHRAE Journal, April 1991, pp. '38-41. Christie, R., and W. McDougald.1992. " Impact of Safety Requirements on Component Availability." proceedings from American Nuclear Society-1992. Meeting, June 7-12, 1992, Boston, Massachusetts. Esslinger, S. 1988. "The True Cost of Refrigerant Ltaks." ASHRAE' Journal, November 1988, pp. 27-29. Gorzelnik, E. F. '1977. " Load Controller Modulates Chillers." Electrical World, November 1,1977, pp. 50-51. g Harmon, J. J. 1991. " Centrifugal Chillers and Glycol Ice Thermal Storage W Units." ASHRAE Journal, December 1991, pp. 25-31. ~' 41

Leitner, G. 1980. " Controlling Chiller Tube Fouling." ASHRAE Journal, February 1980, pp.40-43. Levy, I. S., J. Wreathall, G. DeMoss, A. Wolford, E. P. Collins, D. B. ~ Jarrell. 1988. Prioritization of TIRGALEX - Recommended Components for Further Aoina Research. NUREG/CR-5248 (PNL-6701), prepared for the Nuclear Regulatory Commission by Pacific Northwest Laboratory, Richland, Washington. Niess, R. C. March 1992. Selection of Larae-Capacity Water Chillers in the 1990s. EPRI TR-100537s, prepared for the Electric Power Research Institute by I Gilbert & Associates, Gloucestor Point, Virginia. Starner, K. E. 1976. "Effect of Fouling Factors on Heat Exchanger Design." l_ ASHRAE Journal, May 1976, pp. 39-41. Stebbins, W. L. 1991. " Implementing an Effective Utility Testing Process: A I Keystone for Successful Energy Management." Proceedings of IEEE Annual Textile, Fiber, and Film Industry Technical Conference, Greenville, South Carolina, pp. 1-11. Traver, D. G. 1976. " Saddle Damage of Cooler Tubes." ASHRAE Journal, March 1976, pp. 46-52. I U.S. Nuclear Regulatory Commission (NRC). 1991. Nuclear Plant Aaina Research (NPAR) Proaram Plan. NUREG-1144, Rev. 2, Washington, D.C. Webb, R. L. 1986. " Gas in Refrigerant Condensers." ASHRAE Journal, May 1986, I_ pp. 52-52. I I I

I I

I 42 g

4 ---L. w 4 I I

g-E g

APPENDIX A LWR PLANT CHILLER SYSTEMS DESCRIPTION (FSAR DATA) LI I

I I

I E l g

g is I

I

pl\\ l APPENDIX A LWR PLANT CHILLER SYSTEMS DESCRIPTION (FSAR DATA) This appendix contains a summary of chiller information found by reviewing Final Safety Analysis Reports (FSARs) of U.S. NPPs. Information on ): plant chillers was not found in many of the FSARs. Some of the FSARs reviewed g at PNL were not completely up-to-date. However, it.is believed that this data 3 is' sufficient to be a representative sample of typical NPP systems served by l l-chillers in the U.S. g r l 1I I eI I I I I I 1 A.1 4 L:

M M W M-M M M M M m M M M M M M M. m LWR PLANT CHILLER SYSTEMS DESCRIPTION (FSAR DATA) QUANTITY-REFRIGERATION PLANT / PLANT TYPE CAP. (TONS) EA SYSTEM SERVED Arkansas 1 & 2 2* Not Found Not Found Not Found Beaver Valley 1 & 2 2* Not Found Not Found Control Building 3 Centrifugal 650 Chilled Water System Browns Ferry 1,2,& 3 2* Not Found 171 Control Building Clinton 1 2* Centrifugal 200 Control Room System 2 Centrifugal 500 Drywell System 5 Centrifugal 1100 Plant System 3 Centrifugal 148 Service Building System Comanche Peak 1 2* ea unit Centrifugal Hermetic 101 Safety System (+2 when 6 Centrifugal Herm.(4), Open (2) 1980 Total Second System operational) 3 Centrifugal Hermetic for Both Third System Fermi 2 2* Centrifugal 100 Control Center System Grand Gulf 1 2* Reciprocating 80 Control Room 3 Centrifugal 850 Plant System Hope Creek 2* Centrifugal 536 Control Area 2 Centrifugal 200 Reactor Auxiliaries 4 Centrifugal 1285 Turbine Building Limerick 1 & 2 2* Centrifugal 250 Control Structure System 2 Centrifugal 1500 Drywell System Hillstone 3 2* Not Found 250 Control Building Room 3 Not Found 938 Chilled Water System A.2

M ^ M M,-M. M-M M M M' M M M m: M M 6M M IML LWR PLANT CHILLER SYSTEMS DESCRIPTION (FSAR DATA) 1 QUANTITY fREFRIGERATION ' PLANT t/ PLANT: 1 TYPE CAP.'(TONS) Fl\\ 2 SYSTEM' SERVED Nine Mlle Point 2 2* Centrifugal Hermetic 145 Control Building System 3 Hot Water Absorption 400 Ventilation System-Palo Verde 1,2,& 3 2* Not Found 210 Essential Systems 4 Not Found 213(1),800(3) Normal System Perry 1 3* Centrifugal Hermetic 607 Control Complex 2 Centrifugal Hermetic 800 Turbine Building 3 Centrifugal Hermetic 200 Containment Vessel Shearon Harris 2* Centrifugal Open 752 Essential Services 2 Centrifugal Open 904/847 Non Essential Services South Texas 1 & 2 4* Centrifugal 150(2),300(2) Reactor Control Building 4 Centrifugal 550 Mechanical Aux. Building Trojan 2* Open Reciprocating 57 Control Building System 2 Open Helical Rotary 230 Reactor Aux. System Vogtle 1 & 2 2* Centrifugal 300 Essential System 3 Centrifugal. 1500 Non Essential System WPPSS 2 2* Centrifugal Hermetic 85 Control Room Emergency 2 Centrifugal Hermetic 150 Rad Waste Building Waterford 3 3(2*) Centrifugal Hermetic Not Found Essential Watts Bar 1 2* Not Found 400 Building Coolant System

• Indicates essential chillers.

A.3

u i LI P E I APPENDIX B BERMETIC CENTRIFUGAL CHILLER FUNCTIONAL DESCRIPTION I 1 13-I I: 1 I

g-IL g

{ APPENDIX B HERMETIC CENTRIFUGAL CHILLER FUNCTIONAL DESCRIPTION This Appendix describes how components in a hermetic centrifugal chiller function. It illustrates the refrigeration, motor cooling, and lubrication cycles that occur..in an operating chiller and how the mechanical components .g' interact. The description is from pages 17 through 19 of the Carrier 3 Corporation's Operations and Maintenance Instruction manual for their model 19FA chiller (Form 19FA-IS0). (Permission to use is in progress) I-I I I l g I I . I I I-B1 .g

y-ll} g 3 E . I I l GENERAL DATA CONDENSER - A heat exchanger vessel in which heat is removed from compressed refrigerant and is-Machine Nameplate is located on the cooler carried out of the system. support foot at the suction end of the machine. ECONOMlZER a A vessel at intermediate pressure Always give machine model, serial number and between cooler and condenser which returns " flash - I name of owner in correspondmg with Camer. gas" to the compressor for greater cycle efficiency. pressure differences,OR maintains the necess MOTOR-COMPRESS Compressor Nameplate is mounted on the com. m the system and moves the ~I' pressor support foot on the suction ad of the heat-carrying refrigerant from cooler to condenser. compressor adjacent to the oil pump. CONTROL CENTER controls maclune start and System Components include cooler, condenser, stop, regulates machine capacity as required, con- .l cconomizer, motor-compressor and machine core tains machine safety devices, indicates cooler, J E trol center. A storage tank for the full refrigerant condenser and oil pump pressures and records charge forms the support for compressor and machine operating hours. control center. Most machines are also supplied STORAGE TANK supports machine components I with a machine mounted pumpout unit-and provides a ready storage for the refrigerant charge during machine service periods and at COOLER - A heat exchanger vessel in. which extended shutdown. flashing refrigerant picks up heat from, and there-il fore chills, the water (or brine) flowing thru its PUMPOUT UNIT is used for refrigerant transfer,~ M tubes. machine evacuation and machine pressurizing. I il lI B.2

.t s I +~' l / -. w -, u.j.,,,,, CoND Ib 4h [" 'Y) CoNDINat h. 34 M.nS, m:,4, g l l waggg r CONDENSER . LIQUID LivEL sensor LINE ,,t k HIGH stOE r i FLOAf VALVE F I' FLASH s GJMPREs3oR k COOLING J * }}' N clRCult CoMPRissOR <s< sf, FLASH teoNOMittR \\ 3 HIGH SIDE fU O Low s!DE FLOAT 7, f " bi [ ' ti 1 floAfvALvt CHAMBER I l cHAussR aW J -m9 M N. I Ftow 5 l oR A>N C REFRIGER ANT wor gj (cogt,,j g (Q g j g g,' R E REFRIGERANT LloUID I + = CHILLED W TER WATER Fig.12 - 19FA Refrigeration Cycle 19FA REFRIGERATION CYCLE subcooled by contact with the coolest (entering water) condenser tubes. With the exception of the thermaleconomizer, I which is used on water chilling duty only, the basic The, liquid refrigerant drains into the flash refrigeration cycle described below is applicable to economizer where a valve system maintains pres-cither water or brine chilling. sure intermediate between the condenser and the C let pressure. At this lower pressure, part of the - The machine compressor continuously draws

h. quid refrigerant Dashes to gas, thus cooling the I

large quantitics of refrigerant vapor from the cooler, at a rate set by the amount of guide vane remaining liquid. The ** flash gas" is returned opening. This compressor suction reduces the directly to the compressor second stage. Ilere it is pressure within the cooler and causes the remaining n4xed, wlui gas aircady compressed by the first refrigerant to boil vigorously at low temperature stage impeller. Since the economizer gas has to pass I (typically 30 to 35 F). thru only half the compression cycle to reach The energy required for boiling is obtained as c n enser premre, there is a savings in power, heat from the water (or brine) Howing thru the cooler tubes. With heat removed, the chilled water Tlic cooled liquid refrigerant in the economizer I (brine) can then be used for air conditioning or for is metered thm the low-side float chamber to the process liquid cooling. cooler. Because cooler pressure is lower than the After removing heat from the water, the refrig-ec nomizn pressure, some of the liquid Hashes and e is th remaindu to cooler temperature. N erant vapor passes thru the compressor Grst stage, -I cyc is n w c mplete, is compressed and moves into the compressor second stage. IIere it is mixed with flash-19FA MOTOR COOLING CYCLE economizer gas and is further compressed. Compression raises the refrigerant temperature Refrigerant liquid from a sump at the bottom I-above that of the water flowing thru the condenser of the condenser (Fig.12) is subcooled by passage tubes. When the warm (typically 100 to 105 F) thru a line immersed in the refrigerant within the refrigerant is discharged into the condenser, the cooler. The liquid then enters the compressor relatively cool condensing water removes some of motor end where it sprays on and cools the I the heat and the vapor condenses into a liquid, in compressor rotor and stator. It then collects in the water chilling machines, further removal of heat base of the motor casing and drains back into tiie occurs in the thermal economizer at the bottom of cooler. Refrigerant gas is vented from the com-the condenser. llere the liquefied refrigerant is pressor motor casing and returns to the upper B.3 I I

portion of the cooler thru a check valve. Differ-After it leaves the oil cooler, the oil is filtered ential pressure between condenser and cooler (11) and a portion flows to the motor end bearing maintains the refrigerant flow. (12) and seal The remainder lubricates the com-P'*** 19FA LUBRICATION CYCLE journal bearings (15). Thrust beating temperature II-General - The compressor oil pump and oil is indicated on a gage (16) mounted on the bearing reservoir are located in the compressor base. Oilis inspection cover. Oil from each circuit returns by pumped thru an oil cooler and a filter to remove gravity to the reservoir. heat and any foreign particles. Part of the oil flow A demister (17) and (18), by centrifugal action, 7 is directed to the compressor motor-end bearings draws refrigerant gas from the transmission area to and seat The remaining flow lubricates the com-the motor she!L The resulting pressure difference i pressor transmission, thrust and journal bearings prevents oil in the transmission cevity from leaking and seat Oil is then returned to the reservoir to into the motor shell complete the cycle (Fig. 13). Several safety devices monitor the lubrication . I Lubrication Details - Oil is charged into reservoir system: (1) thru a hand valve (2) which also functions as an In the event of power failure, a small oil od drain. If there is refrigerant in machine, a pump reservoir (19) supplies sufficient oil reserve to ensure is required for charging. Sight glasses (5) on continued lubrication until r.it compressor parts

I reservoir wall permit observation of oil level.

have come to a complete stop. The motorairiven oil pump (6) discharges oil t Solid state sensors (20) monitor motor-winding an oil cooler (7) at a rate and pressure controlled and bearing temperatures and shut off machine if by an od regulator (8). The differential pressure temperature rises above a selected point. .I. (supply versus return) is registered on a gage at the machine control center. Low-oil cutout (Fig.14) shuts down machine Water flow thru the oil cooler is manually or prevents start if oil pressure is not adequate. adjusted by a plug cock (9) to maintain the oil at A program timer in the machine control center i an operating temperature, at the reservoir, of ensures proper lubrication at start-up and at approximately 145 F. During machine shutdown, coastdown by energizing the oil pump for approxi-F the oil temperature is also maintained at 140 to mately 30 seconds before the compressor starts, 150 F by an immersion heater (10) so that. and keeping the pump running for almost one. absorption of refrigerant by the oilis minimized. minute after the compressor motor is de energized. .I st R - I REQ'O T T DOWN) NSER 5 S size ccMPR a REQU BRG mCONNE.CTIONs ggg7gg yg 11 _ j MT N eon IONS g X \\ / 13 I ? O O ~ ~ f s JOUR 4.d. . g.:- L i lI. CHECK H h N /

=

( x k .i . h.- - i m Q 1RANfMiss10N r 3 -= oil COOL \\ 4 l? r E M MEATER s " (( L RESERVOIR em"(_ n AL_ e 2 REGULATOR W W ~ [ g l E T C G MLVE CIL FIE volR Fig.13 - 19FA Lubrication Cycle B.4 lI

a 4 .a a e-a +- 0LJ-- .m a m L h il s LI APPENDIX C i LWR PLANT LER REVIEW

SUMMARY

1 !I. iE W 4 s' i 4.. ji: 1 !I l 'E: I 3: h

l APPENDIX C LWR PLANT LER REVIEW

SUMMARY

I.' This appendix contains a summary of LERs that were compiled using the Sequence Coding and Search Systems (SASS), NUDOCS Database, and NRC Staff sources. Some of these items are redundant with the NPE Database. I I I I I I I I I I I I I C.1 I

M M M M M M M M M M M M M M M MM M M CHILLER LER REVIEW

SUMMARY

-EVENT LER PLANT DATE ' DESCRIPTION CAUSE 81-040 Arkansas 2 11-06-81 Low freon charge. Leaking valve fitting. 83-006 Arkansas 2 02-02-83 High condenser pressure. Power supply for the pressure indicating controller was defective. 90-008 Byron 1 06-27-90 Chiller malfunction. Evaporator tube leak. 86-003 Catawba 1 01-16-86 Chiller failed to start. Chilled water compressor motor tempera-ture sensing module had failed. 86-005 Catawba 1 01-17-86 Chiller tripped on low chilled water Misapplied pump seals and unreliable flow and later on high motor bearing expansion tank alarm. tgmperature. 90-030 Catawba 1 10-23-90 Control room ventilation system Failed hydrometer and out-of-calibration chillers inoperative. oil pressure switch. 91-005 Catawba 1 02-12-91 Low refrigerant temperature cut out Train A, refrigerant leak in compressor switch set point reached on Train A. power terminal box. Train B, condenser Train B also tripped. water auto control valve failed to open. 89-041 Clinton 1 11-22-89 Low refrigerant pressure. Refrigerant leakage, no location reported. 91-018 Comanche 1 05-28-91 Safety chiller inoperable. A faulty oil sump lever switch. 87-012 Hatch 2 09-16-87 Equipment degradation Water chiller fouled by calcium deposits. 86-029 Hope Creek 1 06-11-86 Control area chiller tripped on low Ball float valve that controls refriger-refrigerant pressure. ant flow malfunction. 88-015 Hope Creek 1 05-26-88 Excess oil in one chiller and the lack of understanding of seasonal oil other chiller tripped. migration in first chiller and defective high side float ball in economizer of second chiller. 89-007 Hope Creek 1 04-06-89 Both A and B control room emergency Seal failure in one chiller and failed filtration units became inoperable. damper in the other chiller. C.2

M M M M M M M M M M M M M M M M-M M M CHILLER LER REVIEW

SUMMARY

LEVENT LER-PLANT DATE DESCRIPTION CAUSE 83-056 McGuire 1 07-14-83 Low refrigerant temperature trip. Loose flange on suction side of compressor. 87-001 McGuire 1 01-07-87 Loss of refrigerant. A leaking threaded fitting on. oil cooler. 87-023 McGuire 1 10-01-87 Loss of essential control power in Blown fuse in Train A and failure of an Train A and control room air hand-actuator micro switch for Train B. ling unit suction damper not open causing Train B to be inoperable. 86-015 McGuire 2 08-09-86 Train A tripped. Blown fuse and chiller start mechanical timer not operating. 81-025 North Anna 1 04-28-81 Improperly operating steam chiller. Lack of adequate cooling water. 83-032 North Anna 1 05-21-83 Chiller malfunctioned. No cause given. 83-056 North Anna 2 07-11-83 Chiller tripped on low compressor No cause given. 011 pressure. 85-063 Palo Verde 1 09-12-85 Loss of refrigerant. No cause given. 81-003 Oconee 2 03-02-81 High temperature on reactor building Bearing high temperature caused by chiller unit. grease starvation. 88-019 Perry 1 05-15-88 Chillers inoperable. Mechanical failure of a compressor guide vane linkage connector and an intermit-tent fault in the motor starter circuit of the supply fan. 88-040 Perry 1 10-07-88 Electrical fault in chiller control Degradation of wire insulation results power. in grounding of control power supply. 91-008 Perry 1 03-05-91 Low refrigerant temperature. Malfunctioning solenoid valve on the thermal purge unit. 90-002 Riverbend 1 02-02-90 Chiller shutdown. Indeterminate. C.3

M M M M M M M M M M -M m' M M M M-M M'-M CHILLER LER REVIEW

SUMMARY

EVENT-LER-PLANT 'DATE DESCRIPTION' CAUSE 82-059 San Onofre 2 04-07-82 Found during maintenance. Faulty flow control switch. 82-039 San Onofre 2 07-16-82 Emergency chiller refrigerant com-Defective impeller displacement switch. pressor failed to start. 81-040 San Onofre 2 07-19-82 High bearing temperature. Faulty high temperature bearing alarm module. 82-173 San Onofre 2 12-28-82 Chiller failed to start. Loose wire on the low lube oil pressure switch. 83-012 San Onofre 2 01-08-83 Chiller failed to start. Faulty program timer. 83-043 San Onofre 3 07-08-83 Chiller inoperable. Either a malfunction of chiller control circuitry or mechanical malfunction in the power supply breaker. 90-001 San Onofre 3 01-30-90 High motor / bearing temperature trip Intermittent failure of a trip relay. indication. 87-007 Shearon Harris 02-10-87 Chiller tripped and was restarted Low lube oil.

1. 1 several times.

90-017 Shearon Harris 06-20-90 Chiller could not be started. Hispositioned root isolation valve on

1. 1 the chiller.

88-039 South Texas 1 06-16-88 Failure of chiller lube pump oil Failure of pump shaft bearing. seal. 89-023 South Texas 1 12-16-89 Essential chiller could not be Contact oxidation and low contact pres-secured. sure on an auxiliary relay. 83-019 Summer 1 03-17-83 Chiller failure. Problem associated with starting cir-cuitry of chiller. 86-024 Surry 1 08-13-86 Loss of one control room and relay Clogging of chillers due to unfiltered room A.C. chiller. river water flowing through tubes. C.4

M M M ~M~M M M M M M M M M M'M. M-M -m m CHILLER LER REVIEW

SUMMARY

EVENT LER PLANT-DATE DESCRIPTION CAUSE 86-027 Surry 1 10-09-86 Two of three control room A.C. One out for maintenance, the other in-chillers inoperable. operable because of failed relay. 87-003 Surry 1 02-13-87 Chiller inoperable b6cause of lack Clogged suction strainer and excessive of service water and another because throttling of compressor service water of compressor relief valve lifted, outlet valve. discharging refrigerant. 87-005 Surry 1 02-21-87 The chillers tripped due to insuffi-Marine growth inside of rotating cient service water flow. strainer. 87-006 Surry 1 03-10-87 Service water pump for B control / Suspect thermal overload device at the relay room chiller tripped. motor control center activated, tripping the pump. 88-007 Surry 1 02-24-88 Insufficient service water flow. Bad pressure control valve. 88-039 Surry 1 10-11-88 Control / relay room chiller tripped A small refrigerant leak in combination on high condenser discharge with insufficient service water flow. pressure. 89-023 Surry 1 06-13-89 Main control / emergency switch gear Improper valve line-up. chiller inoperable due to degraded performance. 91-018 Surry 1 04-25-91 Control / emergency switch gear room Failed oil pressure / overload reset chillers inoperable. relay. 88-011 Surry 2 04-23-88 Control / relay room chiller removed Refrigerant filter / dryer was becoming from service to~ perform minor main-clogged. tenance. 87-022 Susquehanna 1 06-19-87 Chiller experiencing spurious trips. Problems with cycle timer and low refri-gerant trip switch. 84-014 Susquehanna 2 07-23-84 Problems in the B Reactor Building. No cause given. 87-049 Vogtle'l 07-22-87 Chiller failure. Temperature switch failure on chiller. C.5

m a

m Mm m m'. m m in M' m m _ m. m :- m c m= 1m m1 CHILLER LER REVIEW

SUMMARY

' EVENT-' ' LER -- PLANT -DATE: DESCRIPTION CAUSE-89-004 Waterford 3 03-03-89 Low pressure valve ball' float devel-Intergranular stress corrosion cracking. oped crack allowing float to fill with freon, sink, and close valve. 90-008 Waterford 3 07-30-90 Compressor motor high temperature. No cause given. 6 l C.6

M ,I I': 1 l il 1 I: I L3 APPENDIX D NPE DATABASE ON CHILLERS I I . i I

• I.

I I.

g

I

.I I I

APPENDIX D NPE DATABASE ON CHILLERS i This appendix contains a summary of the NPE Database that applies to chillers in NPPs. The information is from the NPAR Database at the Oak Ridge National Laboratory. I I I I I I I I I I I I I D.1 I

M M-M M M M-M M -W W M M M' M: M 'M -M.M3M Nuclear Power Experience (NPE) Database on Chillers Plant Date Power Level Description Cause Arkansas One 2 7/79 50% Chiller failed to start. Casting plug lodged in compressor discharge isolation valve. Arkansas One 2 8/79 50% Chitter failed to start. Crankcase oil leak. Arkansas One 2 12/80 16% Chiller failed to start. Freon migration due to cold ambient temperature effects, modifications needed. Arkansas One 2 2/81 90% Chiffer tripped. Expansion valve leak. Arkansas One 2 6/27/81 Hot Standoy Containment temp. exceeds tech specs limit. One chitter out of service and backup has motor winding temp. sensor failed. Arkansas One 2 6/28/81 Hot Standby Containment temp. exceeds toch specs hmit, Power transformer failure. Arkansas One 2 7/4/81 Hot Standby Containment temp. exceeds tech specs limit. Clogged oil fitter. Arkansas One 2 11/81 20% Chiller failed to start. Leaky freon vane fitting. Arkansas One 2 1/83 100% Chilier cycling excessNely. Leaking freon discharge relief valve. Arkansas One 2 7/83 100% Chi!!er tripping due to low freon. Leak found in chilled water hne, other unknown. Byron 1 6/90 98% Containment Chiller B was out of service for major Evaporator tube leak in Chiller A. Single tube was rebuilding. Chiller A tripped on ground overcurrent plugged w/o failure cause, so reactor could restart. due to wet motor windings. Containment temps exceeded 120T and plant was shut down.M Calvert Cliffs 1 10/77 100% Chiller failed to start. Faulty starter control relay. Calvert Cliffs 1 - 5/78 Shutdown Chitler 12 failed to start, sight glass showed no oil Due to low refrigeration load, compressor oil was displaced to evaporator. Calvert CINfs 1 6/79 Shutdown Chilier tripped. Compressor motor winding failed. Calvert Cliffs 1 7/16/80 95% Both chillers tripped. Control roorn got to 94*F.M High compressor discharge pressures, inadequate chiller capacity. Calvert Cliffs 1 7/29/80 95 % One chiller tripped. High compressor motor amperage. Calvert Cliffs 1 8/1/80 95% One chiller tripped. High compressor motor amperege. Calvert Cliffs 1 8/15-30/80 95% 3 times Chiller tripped on high discharge pressure. Unioader valve adjustment required. D.2

M M M 'M M M M M

m. m m

M m m m m m .m' ~ m: Nuclear Power Experience (NPE) Database on Chillers Plant Date Power Level Description Cause Calvert Cliffs 1 9/11/80 95% Both chillers failed to start.I'3 Unioeder vaNo adjusted on one unit and misc. repairs on cther unit. Unipressure valves were replaced by hot-gas bypass and pressure regulating valves to eliminate 7/16-9/11 problems Calvert Cliffs 1 9/80 100% Both essential chillers inoperable.") Faulty reset switch on one unit and operability check inadequate on other unit. Calvert Cittfs 1 8/81 95% Plant computer failed twice due to high roam tempa Chillers have inadequate cooling capacity. (87*F). Calvert Cliffs 1 7/22/83 100% Chiller No.12 compressor tripped. Set screws vibrated loose to drop shaft which damaged fan drive belts. Calvert Cliffs 1 7/27/83 100% Chiller No.11 condensor fan found damaged. Set screws vibrated loose to drop shaft to damage structural support. Calvert Cliffs 1 8/22/83 100 % Chiller wouldn1 start. High pressure switch out of calibration. Catawba 1 49/85 98% Chiller trip on low chilled water line flow. Line compression tank almost empty. Catawba 1 a/12/B5 98% Chiller trip on low chilled water line ficw. Line compression tank almost empty. Catawba 1 ' 4/12/85 98% Chiller trip on low chilled water line flow. Line compression tank almost empty. Problem was domin. water atorage tank float device not working. Catawba 1 1/16/B6 100% Chiller tripped twice, once for low chilied water flow Unreliable domin. water storage tank makeup source. and once for high motor bearing temp. along with Level transmitter malfunction. Motor temp. sensing CR ventilation prob?em. LCO event was required. module failed. Plant power was reduced.") Catawba 1 1/17/86 100 % Both chillers had low chilled water flow and were Chilled water pump leaked and low level computer alarm inoperable. Caused LCO event.Cl and transmitter had failures. Davis Besse 1 7/79 100 % Chiller failed to start. Failed thermistors in motor windings. Davis Besse 1 6/26/89 100% Chiller would not start during test. HP switch had tripped earlier in the month and had not been reset Compressor HP transfer set point was raised. Farley 1 9/6a53 100% Chi!!er compressor trip. Solenoid va!ve linkage on pump down line out of adjustment D.3

W M .M M M M M M M. m m m M-m m m 'm m m: Nuclear Power Experience (NPE) Database on Chillers Plant Date Power Level Description Cause Farley 1 12/3041/83 100% Chiller compressor trip. Freon leak at HP vatve. Grand Gulf 1 6/26/83 Shutdown Control room temp. exceeded 77T fimit. Chiller B Malfunctioning condensor cooling water flow control deficient in cooling.U8 valve. Limit switch on vane needed adjustment. Grand Gulf 1 7/27/83 Shutdown Chiller A shut down to repair freon shutoft vaNo. Valve failed due to norma! wear. Three compressor inlet Vane unloaded the compressor, strainers were blown through, damaging two compressor pistona. Hatch 2 6, 7 & 9/79 72-99 % Chillers serving dry well tripped. Personnel tripping and/or swapping chillers. Hatch 2 4/80 71-99 % Chiller B tripped and Chitler A failed to cool Chit!ar B oil pump failed and Chiller A guide vane arm adequately.03 failed. Hatch 2 5/90 71 99 % Chiller tripped, SW flow throttling by operators caused high head pressure in chiller. Hope Creek 5/88 100 % Chiller A down for scheduled PM. Chiller B down Chiller A problem caused by seasonal oil migration due for repair. Control room temp. increased. LCO to lower loads. Chiller B problem caused by compressor entered and plant shutdown initiated.M float design deficiency (weld failure susceptible). Design was modified. McGuire 1 9/82 50 % Chiller B tripped due to high bearing temp. Eartier Excessive oil added due to procedural error. Oil was in month, Chiller A tripped for same reason. removed and procedure was modified. McGuire 1 6/4/84 100 % Chiller trip due to low oil, both ventilation trains Chiller underloaded, oil deposited in evaporator, due to inoperable, LCO issued and plant power reduced.") oversized chil ers. McGuire 1 10/17/85 100% Chiller tripped 3 times on low chilled water flow, Cause of trips not found, other unR down for PM.W McGuire 1 7/3/86 Refueling One chiller tripped on low oit level, second chiller Low oil levet due to etnller being operated below 100% would not start due to low chilled water flow, tech capacity, e design problem to be solved by modifying spec LCO applied. Control room temps. rose.W vane settings on hot gas bypass. Low chilled water flow problem required control circuit modifications and numerous other items. McGuire 1 - 1/7/87 100 % Chiller B tripped on low refrigerant temp. Earlier, Chiller B tripped due to chiller thermostat being set too Chitler A failed to start. LCO event initiated. tow. Chitler A had freon leak through the oil cooler Control rooms maxed out at 837,l'3 threaded fating. D.4 ~.

M M M M M M ' M-M M M M M M -M~ M Nuclear Power Experience (NPE) Database on Chillers Plant Date Power Level Description Cause McGuire 1&2 7/81 4/84 Various Chill trip on low olt, control room temp. rise leads to High temperatures in control cabinets cause cards to printed circuit card failures which create spurious create spurious indications. alarms and instrument readings. Temps. 86-90*F outside cabinets. McGuire 1&2 6/24/86 69% Chitler tripped on low refrigerant temp. Recent!y cleaned condensor tubes had high heat transfer, which caused low temp cutout switch to trip. McGuire 1&2 7/14/86 Cold Shutdown Chiller tripped again on low reft:gerant temp. Loose flange on compressor euction side caused refrigerant leak. Also controller needed calibration. May have also contributed to 6/24/86 event. North Anna 1 5/78 95% Containment temp. exceeds tech specs limit Absorption chiller steam noz:les and strainers clogged, gask et leak. North Anna 1 5/78 Hot Standby Containment temp. exceeds toch specs 1.mit. Absorption chiller tubes fouled. North Anna 1 8/t8/78 95 % Absorption chiller not functioning, caused incorrect valve line-up dumped all condensate from the containment temp. hmit to be exceeded (>105'F). chiller condenser. Backup chiller brought temp. back down. North Anna 1 4&5/81 100% Containment temp. exceeds tech specs limit. Absorption chiller operating improperty and mechanical chiller out of service. North Anna 1 6/81 100% Contamment temp. exceeds tech specs limit. Switch problem from absorption to mechanical chiller. Perry 1 6/90 100 % Chiller A outlet temp. and refrigerant pressure Guidevane linkage had slipped on the shaft to the readings were high. guidevanes. All 3 chillers needed modification to prevent set screw slippage. River Bend 1 11/85 5% Containment chillers tripped and temperature Voltage transient caused trip and operator failed to increased in containment. restore cooling water to containment coolers in timety manner. River Bend 1 2/90 100% Four chillers were inoperable. LCO entered and Chiller 1 A failed to start due to inadequate chilled water plant shutdown initiated.W flow because of low building temp. and valve control problem. Chiller 1D breaker needed resetbng due to unknown interiock and over-current trip. Flow bypass and valve control procedure was needed. River Bend 1 3&4/90 100 % Chiller C tripped. The motor current hmiter was set too low. D.5

LW W W~ M M M M ~m m W m m m m-m

m. > m

m. mL Nuclear Power Experience (NPE) Database on Chillers Plant Date Power Level -

Description Cause San Onofro 2 7/11/82. Hot Shutdown Both essential chillers inoperable. Trip relay cover improperty installed and fauhy temperature module. San Onofre 2 7/16/82 Hot Standby Unit compressor failed to start Defective impeller displacement switch. San Onofre 2 7/19/82 Hot Standby Both essential chillers inoperable. Fauhy high temperature beanng alarm in one unit. San Onofre 2 11/28/82 50% Both essential chillers inoperable,08 One unit out of aervice and other unit had f aulty Ngh temp. motor winding RTD. San Onofre 2 12/18/82 Cold Shutdown Both essential chillers inoperable. One unit out of service and other tnpped on high beanng temperature. San Onofre 2 3,2/83 Cold SD Chiller A failed to start Chitled water flow control switch inadvertently valved out. San Onofre 2 4!22/87 Cold SD . Chiller B stalled during testing. Valve closed on compression tank surge line. 2 San Onofre 2&3 4-10/83 Various Series of electrical problems to both chillers. Caused LCO problems due to lost inverters and loss of air cooling for LOSp. TGis, and Si events. San Onofre 2&3 4/29/83 Chiller start failure. Supply breaker misalignment San Onofre 2&3 6/1/83 Chiller inoperable. Control circuitry and breaker problems. San Onofre 2&3 8.21/83 Chiller failed to start. Fuse failure. San Onotre 2&3 10'21/83 50 & 100% Chiller tripped twice. Spurious alarms for low CCW flow. San Onofre 2&3 5/84 100% Jumper installation error caused chiller to start and Restart failed due to stuck microswitch in program timer, then trip. As a result, two invertors were inoperable. and LCO was invoked?I Sequoyah 1 5/80 Shutdown invertor room temperature high. Chitler thermostat out of calibration. Summer 3/17/B3 50% Train A chiller inoperable. CanVmicroswitch misalignment. Summer 3/25/83 Cold Shutdown Train B chiller inoperable.. Faulty isolat>on valve control switch. Surry 1

• 9/9/83 100 % '

Two of 3 chillers inoperable. One downior main-Blown condenser zine plug caused motor starter tenance and other had control panet catch on fire. contractors to short. Surry 1 8.28/B8 Cold Shutdown A!! essential chillers inoperable. Lack of service water cooling, inadequate CCW HX-filling procedure. 0.6

M M -M'- W. M M W-M M m~m M.m M 'M - m ' mi:. ~ Nuclear Power Experience (NPE) Database on Chillers Plant Date Power Level Description Cause Surry 1 8/15/88 Hot Shutdown All essential chillers inoperable. Lack of SW cooling due to inadequate chiller starting / stopping procedure. Surry 2 3/81 100% Two of 3 chillers inoperable. SW strainer was clogged on one unit. Turkey Point 3&4 7/26/s6 100% Potential loss of 3 compressors and air handlers in Transfer switch stuck during safeguards test. CRVS. Loss of power at MCC's a concem. Circuits jumpered temporarily. Turkey Point 384 12/19/06 100% MCC transfer switch failed. Concem for Transfer switch cover plate was improperty designed. subsequent f ailure of chiner compressors to be operable. (1) Situations where all essential chillers are inoperable. Often causes LCO event. Sometimes plant shutdown. (2) - Complex situation with two plants sharing common power supplies, etc. 0.7

y

I

I I APPENDIX E I IPRDS DATABASE MAINTENANCE REPORT

SUMMARY

FOR NUCLEAR POWER PLANT A iI I ( ll I l

APPENDIX E IPRDS DATABASE MAINTENANCE REPORT

SUMMARY

FOR NUCLEAR POWER PLANT A l This appendix contains a summary of chiller maintenance record data from a single NPP (Plant A). The information is from the IPRDS Database at the Oak-Ridge National Laboratory. The plant and chiller identification is confidential. I I I I I lI 3: I !I I I .I I

il

I-Chiller Maintenance Records for Plant A, Chiller 1A ll.

Date Description of Problem 10/18/82 Gasket blown. -l 10/18/82 Need to' install a press gage on the high press top of FS. 10/20/82 Anti-recycle timer has loose internals; contacts some-I- times makeup. 03/03/83 Chiller high discharge pressure safety switch shutting down chiller. 03/03/83 Condenser oil cooler tubes are getting plugged up, chiller can't make 100%. 08/12/83 011 temperature sensing element should be located on oil line down stream of 011 pump. .l 08/28/83 Chiller condenser tubes plugged. 11/30/83 Cannot read delta on lube oil filter. Replace oil filter. 03/27/84 Chillers been tripping lately, with safety switches light on and 2TR relay. l 03/30/84 Cannot get chiller loaded, oil pump breaker keeps tripping off. E 05/11/84 Control building chiller tripped on oil pressure l3 failure. 05/15/84 Suspect that the heat exchangers are becoming fouled again. 05/29/84 Chiller when in ' auto' tripped on low oil pressure. Slide VLV went T. 05/29/84 Chiller has oil leak on discharge pipe from oil pump. 06/14/84 Won't start. Not enough oil pressure hot gas B/P f doesn't open. 07/22/84 Chiller tripped on low oil press. The alarm would not l reset. 08/01/84 Lube oil filter dP is 22#. Limit is 8-12. 10/31/84 The "A" chiller trips with no associated alarms for indication of trip. 12/06/84 Several oil leaks including mechanical seal and oil drain plug. E.2 I T

f Chiller Maintenance Records for Plant A, Chiller IA Date Description of Problem 02/23/85 Chilled water temperature too high. 03/16/85 While removing fire barrier from tray section IL-3A cable 18-305A nicked. 03/16/85 Cable IB305A given temperature fix on MAR 061346 on due 'I to being nicked and then shorted out. 03/26/85 Leaking oil, appears to be leaking at compressor seal near coupling. 06/17/85 Condenser on this chiller needs to be cleaned. 06/24/85 "A" chiller safety switch will not allow starting of IV-CH-1A. 06/24/85 Hot gas B/P solenoid does not open. 06/24/85 1C026/B5 alarm; "A" chiller trouble in solenoid. There is no apparent problem. I 06/24/85 "A" chiller will not start due to safety switch acti-vation. 07/06/85 On a startup sequence the oil pump comes on but will not -I. clear / reset low. 07/21/85 "A" chiller shows characteristics of being very low on freon. Low suct pressure. ~ 07/21/85 011 plus discharge pressure gauge missing. .E 08/08/85 "A" chiller trips off on low temperature (oil sump) even g-when oil temperature shows ok. 08/08/85 "A" chiller slide valve operation is sporadic. 01/06/86 Plug and seal top panel" openings of chiller starter cabinet. 'E 04/23/86 011 pumps does not develop a discharge pressure.

E Chiller tripped on low oil pressure.

04/26/86 Oil leak of I drop /10 seconds from the southern most l compressor load / unload solenoid. 04/28/86 100% current limit setting is 180 amps while motor nameplate is 230A. I -05/19/86 It tripped on low oil sump temperature when sump temper-ature was 125*F and switch was set at 90. Switch and/or gage needs checked. E.3 I

h E I Chiller Maintenance Records for Plant A. Chiller IA .f Date Description of Problem 06/01/86 Chiller fails to start due to low oil pressure; low oil level. 08/03/86 Liquid line sight glass 1/2 full. As per IP200 it should be full and clear. 08/14/86 Anti-recycle timer not set at 15 minutes per vendor-manual. ' E 10/20/86 Temperature load controller not holding chilled water ' E temperature steady. Temperature keeps dropping for a given setting. 11/11/86 Condenser head gasket is leaking (East end). 11/13/86 Relays and relay block terminal boards need to be g replaced; due to sloppiness in pin connection board. !E l Switching relays and blocks: ISR, 2SR, 3SR, and 4SR. 11/22/86 011 leak on connection on the Southern most unloader I assembly solenoid valve. The leak is on upper con-nection between the solenoid operator and the valve body. 11/22/86 Oil leak on load solenoid valve. 12/08/86 Small freon leak on sts of load solenoid valve. This leak persisted after installing solenoid valve repair

l kit.

12/14/86 011 and refrig leaking from suction flange of compressor -E and manual isolation unloading valve at the compressor ll near suction flange (leak is very small). 04/03/87 Does not dump hot gas at low load (<20%). 04/26/87 The " low 0.7 temperature" alarm light socket broke and shorted out. The chiller will run without it, but we have no " low temperative" indication. 04/28/87 The "A" chiller has tripped 3 times today. No alarm conditions were indicated by the' time the second ASST got up there. Readjust oil pickup valves, adjust TCU lI for the water. 05/01/87 A chiller waterbox gasket is blown out. 05/16/87 Has an excessive oil leak as evidenced by lowering oil pressures and increasing leak-off bottle level. This bottle level is increasing. E.4 i P

I I Chiller Maintenance Records for Plant A, Chiller IA I Date Description of Problem ~ 06/22/87 Chiller is getting low on oil. Oil addition required unit to be shut down about one hour. 1 07/20/87 Chiller condenser needs cleaning. 07/21/87 Check oil cooler tubes for cleanliness. j. 08/11/87 Mechanical seal of compressor still leaking. 08/18/87 Chiller tripping on oil press failure. ( 09/09/87 Insufficient cooling in condenser. Believe tubes need I to be cleaned. I lI E i I x J W' W W u E.5 M ~. ________i___________________

I Chiller Maintenance Records for Plant A, Chiller IB Date Description of Problem 02/26/81 Chiller was not operating correctly. f 05/04/81 Low oil pressure. 05/19/82 Chiller has low oil pressure after 2 days of running. I 07/20/82 Gasket rupture on well WTR/FSW piping between condensate and cond outlet. 07/24/82 Gasket leak on chiller condenser, West side of condenser- . I-between end bel. 08/03/82 Control building chiller will not control load in auto. It always drifts. 10/18/82 Gasket ruptured. 10/18/82 Need to install a press gage on the high press top of FS. 10/19/82 Copper line from sniffers to compressor suction line has crack and is leaking. 02/27/83 Condenser and oil cooler tubes are getting plugged. 03/10/83 TLC load signal causing load solenoid to chatter. 03/15/A3 Chiller circuit power on local panel keeps tripping; chiller must be C. 07/13/83 Cannot read delta on lube oil filter. 07/17/83 011 sump has low oil level; no level is visible with chiller on. 08/30/83 Chiller condenser tubes plugged. l 11/08/83 Will not start. 11/09/83 Timing for anti-cycle does not work. j 04/03/84 Timing for anti-cycle does not work. 04/16/84 Motor termination box for 200 HP chiller motor has a hole burned in it. 05/17/84 Chiller tripped. 06/14/84 Control building chiller cycles ~ continuously _ between I-loading and unloading. F 07/09/84 Leaks oil from oil regulator that control slide valve. 12/17/84 Vertical run on oil pickup line has a crack in it. E.6 I i

? g Chiller Maintenance Records for Plant A, Chiller IB I Date Description of Problem 04/30/85 Condenser refrigerant service valve leaks by seal. f 05/07/85 Install temperature DP indicators across two-flow switches. .g. 05/19/85 Three-way well water inlet valve to chiller condenser 3-stuck closed. 05/20/85 Gaskets on both ends of chiller condenser are bad. Gaskets blown. 05/27/85 011 leaks on unload solenoid throttle and load indicator housing. 05/29/85 Anti-recycle timer times out in 7' minutes. 06/01/85 While performing PMAR on chiller, found contacts l carboned over and badly arched; needs replacement. 06/03/85 Load solenoid chatters at near temperature set point. 06/23/85 "B" chiller unloaded and stopped for STP. When restarted, would not load. 06/25/85 "B" chiller loading solenoid valve is chattering due to I chiller loading and unloading. 06/25/85 Circuit power button trips off. No safety switch trips on chiller. 09/24/85 Chiller will not load beyond 50% (loading solenoid is energized). 01/06/86 Plug and seal top panel openings of chiller control panel. 08/04/86 Anti-recycle timer times out in 4 minutes. 08/27/86 The East end of chiller has a lagged pipe that connects the chiller and compressor has an oil leak. Oil-is leaking from under the lagging. 09/01/86 Uppermost oil pickup line has a cracked flare fitting. -l 09/08/86 Oil pressure is low reading 33#'s instead of the normal 60#. g 09/26/86 Load control unit was found to be rapidly blinking the g; load and unload lites on and-off causing loading. solenoid valves to chatter continuously. E.7 I y

lI I Chiller Maintenance Records for Plant A Chiller IB Date Description of Problem s 10/05/86 Chiller cycles (loads) on and off. This MAR can be referenced to what was worked on 10/1/86 and problem still existed after sign off. 11/13/86 Relays and relay block terminal boards need to be I replaced due to sloppiness in pin connection board. Switching relays and blocks ISR, 2SR, 3SR, and 4SR. 02/13/87 Install new ejector valve and oil jet pump. 02/21/87 Chiller tripped twice and was running with low suction press (45#) high oil temperature. See attached readings chiller will not run now. Trips on low suction. Leak ^I-needs repair. 06/23/87 "B" chiller needs to have freon added to it. 08/24/87 Temperature load control current limiter does not allow motor to go to full load amps, thereby reducing full load capacity of chiller. Resistor needs to be adjusted. I I il !I I

g:

lI I E.8 .I

y a m. a I-I I. I ] I amNmx e I CHILLER WORK REQUEST

SUMMARY

FOR NUCLEAR POWER PLANT B I. I I

I I

I I it !I I g I

-i APPENDIX F CHILLER WORK RE0 VEST

SUMMARY

FOR NUCLEAR POWER PLANT B This appendix contains a summary of the Nuclear Power Plant B chiller maintenance, work-request database. The information was provided by a cooperating utility from their maintenance data base..These two chillers are non-safety, and they are relatively new. I I I I I I I I I I i I F.1 I

I I Work Request Summary for Plant B, Chiller IA Date Work Request Description 01/08/88 Verified S/D oil level, ran unit and monitored oil level for 4 hours. Oil less than 1/2 sight glass, no draining I required. 01/08/88 Voided level normal per vendor operating procedures. 03/30/88 Removed test gages from chiller, capped test gages and sensing lines. 04/27/88 Drained evaporator and purged with N2. 12/04/90 Completed flushing unit. 'I 12/05/90 Removed chiller float assembly, placed on storage racks. ) Removed condenser and evaporator water heads, cleaned inner surfaces. Fabed flush fixtures, covers, blind flanges, etc. for flushing cond/evap shell. I 12/27/90 Cut pipe on elbow socket, tightened nipple into float chamber nozzle, rewelded socket. 01/17/91 Fabricated magnetic liquid level indicator, piping hanger and installed. Performed hydro test on level indicator. Repainted new hanger, installed insulation on level indicator piping. 02/01/91 Repair'ed plug welds as required in Section XI plan, .I appeared to be solid and sound when finished. 01/21/91 Installed two 12 pt. screws. 02/27/91 All electrical components on the chiller skid and in the !l control panel cleaned, inspected and tested. Various terminal UGS.and electrical components were replaced per ? MWR instructions. Startup of the chiller was per specifications. 06/10/91 Fabricated cover and gasket. 09/26/91 Replaced cover. 12/03/91 Applied adequate heat and sufficient leverage to free shaft from bull gear. Cleaned threads and shaft ll. surface. 11/22/91 13 access holes were cut and plates were stamped and bagged tubes from condenser and evaporator were removed. I Cleaned purge unit. Cleaned inside shell, wire brushed i 4 and sand blasted. Removed debris from shell.

I F.2 I

I

I LI Work Request Summary for Plant B, Chiller 1A Date Work Request Description 01/29/92 Cut service water supply piping to condenser, then cut "I off chilled water supply piping to evaporator, re-installed and hydrotested SW and CCH piping IAW Section. XI plan. I-02/07/92 Obtained spare jet pump solenoid from warehouse, removed solenoid and installed it on this chiller, installed new terminal board and replaced flex conduit. 03/04/92 Performed calibration as required. 04/02/92 Painted chiller. f 03/04/92 Prepped, reinstalled and welded access cut out plates back onto shell IAW MWR and section XI plan. Performed pneumatic testing on shell per test requirements. ~ 03/04/92 Installed new evaporator tubes per MWR-and Section.XI plan number 2-0667 instructions, installed new mist eliminator and reinstalled expanded metal, installed and welded plugs in damaged tube sheet holes per change notice #1 of Section XI plan. 06/30/92 Added oil. 'I. l I LI !I (I L

IL lI j'

F.3 ll

I I Work Request Summary for Plant B, Chiller IB Date Work Request Description 01/05/87 Void; no work required. Unit has held it's charge since 11/09/86 without any loss of pressure. 01/22/87 Removed freon charge from A/B units, removed float chamber cover. Removed wire tiedown from float I. assembly, evacuated, purged with N2. Evacuated second time, checked for leaks. Charged.with 650# freon 11. Started and ran both units. Set hotgas bypass linkage. Torqued bolts to 80#. 04/02/87 Removed and replaced oil pump from vendor, changed pump discharge tube fitting. Run pump, checked rotation. 'I: Checked for leaks, found none. Rebuilding of pump will be done. 01/11/88 Started unit', monitored oil level for 4 hours, drew 1/2 gallon of oil to keep level <1/2 upper sight glass. 04/25/88 Lack of run capability caused by a bad valve -lineup. 07/06/88 Replaced oil filter. 04/27/88 Simulated all alarm sensor actuations, all operate fine. 06/29/88 ' Void, no work required. 07/07/88 Void, no work required. 08/17/88 Added about 2-1/2 gallons of oil. 05/25/90 Added approximately 625 lbs. freon R-11. 09/19/91 Installed liquid level indicator on expansion piping at chiller. g. 11/14/91 Replaced refrigerant filter, leak checked, repaired g leaks, serviced with R-11. ~ 12/13/91 Removed jet pump solenoid valve and rotated 180' and reinstalled. Charged syshm with oil and R-11, test ran I' machine. 12/16/91 Changed oil filter and replaced with new oil. Solenoid I. valve coil needed replacement, also removed bottom of. jet pump for inspection and reassembly, continued trouble-shooting steps. 'l 01/16/92 Installed test-equipment for degraded voltage test. Perform preventive maintenance. Disconnected test equipment for degraded voltage test. F.4 I

ta a .a a <,I il g I g APPENDIX G I ~ ANS PAPER COMPARING SAFETY AND NON-SAFETY CHILLERS LI .I I

I

-I. I

g il

I I

I

I APPENDIX G ANS PAPER COMPARING SAFETY AND NON-SAFETY CHILLERS This appendix contains a transactions summary of a paper that compares safety and non-safety chiller failure experience at the River Bend NPP. The paper was presented at the American Nuclear Society (ANS) 1992 Annual Meeting-I in Boston, Massachusetts, June 7-12, 1992. This summary is from ANS Transactions, Volume 65, June 1992. Pages 303-305. (Permission to use is in progress.) "I LI I

I lI

!I I l .I 1 I I 4 I I. a1 I; e

.M-4. Impact of Safety Requirements on Component Availability, Bob Christle (RAPA), Wendell McDougald (Gulf States Util, St. Francisville) The purpose of this work was to show the impact of safety requirements on the availability of similar components. It is generally believed that

3

" safety-related" equipment is more-reliable that,non-safety-related equipment.

3 This is not always the case. This work documents the negative impact that safety requirements can have on component availability.

As part of the System Reliability Program at the River Bend Nuclear Station, component availabilities were calculated and trended for the control building chillers (safety related) and for the turbine building chillers (non- 'g' safety related). There are four control building chillers (A and C in 3 Division I; 8 and 0 in Division II) with only one chiller running at a time. There are three turbine building chillers (A, B, C) with two running at a time.

I The chillers are very similar in design. All the chillers have been cooled by the same normal service water and powered by essentially the same electric power sources. The major differences in the chillers are as follows:

1. Control Building Chillers Manufacturer: Carrier Model MFA 443 Size: 189 t Loading: Mostly throttled 2. Turbine Building chillers Manufacturer: Trane Model N0X-T52-WV2 Size: 1250 t Loading: Generally fully loaded. The availabilities of the non-safety-related turbine building chillers have been generally above the availabilities of the safety-related control building chillers. Tables I and II (see next page) show the run hours,-. fail hours, availability, number of failures, mean-time-to-failure, and mean-time-to-repair of the respective chillers. The key difference _is the mean-time-to- -E failure of the average turbine building chiller versus-the mean-time-to-5 failure of the average control building chiller. The safety-related control build.ing chillers fail approximately three times as often. The safety-related control building chillers-' fail 'approximately three. . times as often as the non-safety-related turbine building chillers because of the stringent control requirements imposed on the control building chillers. The control building chillers must meet the single-failure criterion and must ~ respond automatically to a wide variety of changing parameters following any. perturbation in the control building chilled water system..This added- , complexity in the control building chillers has.resulted in a significantly lower availability and a significantly higher maintenance and operation burden c on plant personnel. h The control building chillers are included in the. technical specifications for the' plant because of their safety classification. Because l G.2 I' ~ 4 e

I of the lower availabilities of the control building chillers, the. conditions. that place the system in a limiting condition of operation (LCO) are l I frequently entered. Operations and maintenance personnel have been able to -l avoid plant derating due to exceeding the'LC0 (time).in the period covered in the Tables I and II. However, the plant was derated twice in 1987 because of .I-problems with the control building chillers. While the final numbers have not yet been compiled for calendar. year 1991, the same pattern is continuing. The non-safety-related turbine building I: chillers have achieved an availability of >99% while the availability of the safety-related control building chillers dipped below 80% in 1991. I I I I I 1 I .I I I I I 'I .I I G.3

I Reliability and Risk Assessment b; TABLE I Turbine Building Chillers 1988 1989 1990 TOTAL HVN-CHLIA Run Hours 6379 4480 3750 14609 Fail Hours 20 0 0 20 .I Availability 99.7 100 100 99.9 Failures 3 0 0 3-4870 MTTF 2126 6.7 MTTR 6.7 HVN-CHLIB Run Hours 4627 4863 5403 .14893 Fail Hours 187 30 387 604 Availability 96.1 99.4 93.3 96.1 Failures 4 2 4 10 MTTF 1157 2432 1350 1490 MTTR 46.8 15 97 60 HVN-CHLIC Run Hours 6387 3365 4693 14445 Fail Hours 665 29 76 770 Availability 90.6 99.1 98.4 94.9 Failures 4 2 2 -8 MTTF 1597 1680 2350 1810 MTTR 166 14.5 38 96 ALL Run Hours 17393 12708 13846 43947 Fail Hours 872 59 463 1394 Availability 95.2 99.5 96.8 96.9 Failures 11 4 6 21 MTTF 1581 3177 2308 2090 MTTR 79.3 14.8 77.2 66 I I g

g G.4 il-

+

q I Reliability and Risk Assessment TABLE II (Paper i) Control Building Chillers 1988 1989 1990 ALL HVK*CHLIA Run Hours 3654 1650 2356 7660 Fail Hours 96 2 2 100 I Availability 97.4 99.9 99.9 98.7 Failures 6 2 2 20 MTTF 609 825 1150 766 9 MTTR 16 1 1 10 HVK*CHL1B Run Hours 2102 2723 1588 6413 I Fail Hours 46 2 820 868 Availability 97.9 99.9 66.0 88.1 I Failures 3 6 2 10 MTTF 350 1360 794 641 MTTR 7.7 1 410 86.8 iB HVK*CHLIC Run Hours 1292 1516 1101 3909 E Fail Hours 82 5 5 92 Availability 94.0 99.7 99.6 97.7 Failures 4 2 1 7 MTTF 323 758 1101 558 MTTR 20.5 2.5 5 13.1 HVK*CHL1D Run Hours 1739 615 2130 4484 Fail Hours 8 775 254 1037 Availability 99.5 44.2 89.4 81.2 Failures 3 2 3 8 MTTF 580 310 710 561 MTTR 2.7 390 85 130 ALL Run Hours 8787 6504 7175 22466 Fail Hours 232 784 1081 2097 Availability 97.4 89.2 86.9 91.5 Failures 19 8 8 35 I MTTF 460 813 897 642 MTTR 12.2 98 135 60 I I G.5}}