May 11, 1981

4RELATED CORRESPONDENCE

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cocwd b1 'INITED STATES OF AMERICA ff M*Uin CLEAR REGULATORY COMMISSION'-

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3 BEFORE TriE ATOMIC SAFETY AND LICENSING BOARD

6 %7 z4

N5 In the Matter of )

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6 HOUSTON LIGHTING & POWER COMPANY ) Docket No. 50-466)

7 (Allens Creek Nuclear Generating )Station, Unit No. 1) )

8: )

9TESTIMONY OF RICHARD A. CLARKE AND

10- JOSEPH F. MONTALBANO ON BEHALF OFHOUSTON LIGHTING & POWER COMPANY

11 ON DOHF'_Y CONTENTION 10 -DIESEL GENERATOR RELIABILITY

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13 0 Mr. Clarke, please state your name and place of employment.

14 A. My name is Richard A. Clarke and I am employed by the

15 General Electric Company as a Senior Engineer in the

16 Systems Engineering Section.

17 0 Would you describe your professional qualifications?

18 A. My professional qualifications are set

19 forth in Exhibit RAC-1 to this testimony.

20 0. Mr. Montalbano, please state your name and place of

21 employment.

22 A. My name is Joseph F. Montalbano and I am employed by

23 Ebasco Services, Inc. as a Supervising Electrical Engineer.

24 Q. Would you describe your professional qualifications?

25 A. My professional qualifications are set

26 forth in Exhibit JFM-1 to this testimony.

27 Q. Mr. Clarke, what is the purpose of this testimony?

28 A. The purpose of this testimony is to address Mr. Doherty's

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2 contention which alleges that the diesel generator system

3 for the High Pressure Core Spray (HPCS) system at

4 Allens Creek as well as the rest of the nuclear plant

5 is not reliable in start uand operation. As a basis

6 for the contention, Mr. Doherty cites Nuclear Safety,

7 Volume 19, No. 1 and Volume 20, No. 1 and No. 2, which

8 report instances of past failures of diesel generator

9 systems. Mr. Doherty also cites an NRC contractor report

10 NUREG/CR-0660 " Enhancement of On-Site Emergency Diesel

11 Reliability" which examines the past diesel generator

12 system failures cited in Nuclear Safety and other

13 publications and makes specific recommendations to

14 address the root causes of the failures.

15 The testimony will describe Applicant's responses

16 to the recommendations of NUREG/CR-0660 and Applicant's

17 evaluation of NRC Inspection and Enforcement Circulars

18 which pertain to diesel generator systems reliability.

19 I will address the HPCS diesel generator while

20 Mr. Montalbano will address the Division 1 and Division

21 2 safety diesel generators.

22 Q. Mr. Clarke, directing your attention to the HPCS diesel

23 generator, and Mr. Montalbano, directing your attention

24 to the Divisions 1 and 2 safety diesel generators, please

25 describe Applicant's responses to the recommendations

26 of NUREG/CR-0660.

27 A. The stated intent of the program described by NUREG/CR-

28 0660 is to arrive at specific recommendations for ACNGS

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2 aimed toward preventing the occurrence at ACNGS of diesel

8 generator problems observed at operating plants. To ensure

4 that the concerns listed in this document have been ad-

5 dressed, an item by item response is provided below. As

6 in NUREG/CR-0660, the responses are classified into

7 three basic categories based upon the suggested

8- corrective action. These are:

9 A. Most Significant Corrective Action

10 (1) Air Dryers in compressed Air starting systems

11 Water in the air starting systems has caused

12 rust, pipe scale, and corrosion to take place in the air

13 starting system piping. This in turn has caused corrosion,

14 jamning and scoring of the internal surfaces of the starting

15 motors. In order to keep the moisture in the air from

16 condensing in the compressed air starting systems, NUREG/

17 CR-0660 recommends the use of air dryers, specifically

18 the refrigerant type.

19 The purpose of an air dryer is to reduce the

20 pressure dewpoint of the compressed air in the starting

21 system to a value below the ambient air. The pressure

! 22 devpoint of the air is a function of the amount of

l 28 moisture mixed with the air. By removir.c moisture

24 with the ait dryers, the pressure dewpoint is lowered,|

| 25 thereby lowering the temperature at which the remaining

26 water in the compressed air will condense. Regenerative

27 dessicant dryers are currently specified for use in thei

28 air starting systems of all three Allens Creek safety

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2, diesel engines. This type of air dryer removes moisture

3 by an adsorptive process. The refrigerant type dryer pre-

4 ferred by NUREG/CR-0660 will be evaluated for use on the

5 Allens Creek safety diesel engines. Such an evaluation

6 will include the considerations raised by NUREG/CR-0660 as

7 well as the recommendations of the diesel engine suppliers.

8' (2) Air Quality in Diesel Generator Room

9 This section focuses upon failures which have

10 occurred due to the build up of dust and grit on the

11 contacts of electrical relays. At Allens Creek, due to

12 the large volume of air which is required to maintain

13 the appropriate room temperature, the ventilation air

14 cannot be restricted to an elevation 20 feet above ad-

15 jacent ground surfaces. However, the Allens Creek

16 specification requires that a NEMA 12 enclosure (dust

17 tight) be provided for instruments, relays, control

18 switches etc. Where louvered cabinets are required

19 for proper heat dissipation, washable filters will be

20 provided to preclude the entrance of foreign material.

21 (3; (3) Turbocharger Heavy Duty Gear Dri,ve

22 The turbocharger deficiencies reported in

23 NUREG/CR-0660 deal with the two-cycle diesel engine

24 produced by General Motors, which is used as the

25 standby power supply for the HPCS. A two-cycle

26 diesel engine does not have enough energy in the

27 exhaust gases at no load to drive the turbocharger.

28 Therefore, the turbocharger is mechanically gear

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2|' driven at no load and at light load conditions.'

3 The turbocharger gear drive has experienced some

4 failures due to a horsepower overload at no load or

5 light load conditions. This situation can be remedied

by either placing limits on light load or no load opera-

6|7| tion which are extremely restrictive, or by upgrading

8 the strength of the gear drive and thus relaxing the no

9 load and light generating restrictions. HL&P has

10, chosen to replace the present 18:1 gear ratio with the

11 new 17.9:? heavy duty gear drive assembly. This will

12 result in the following warranted no load and light

13 load operation:

14 (a) 2000 hours accumulative time at less

15 than 20% of rated load;

16 (b) 4000 hours accumulative time limit between

l'7 20-50% of rated load.

18 The Division 1 and Division 2 safety diesels for Allens

19 Creek are four-cycle engines which utilized a gas turbine

20 turbocharger. With this arrangement, the engine is

21 naturally aspirated during starting and low power

22 operation. The gas turbine turbocharger provides the

28 appropriate air mixture when the unit is operating at

24 rated load. Therefore, due to the nature of the design,

25 the deficiencies reported in this section of the NUREG

26 are not applicable to the Allens creek Divisions 1 and

27 2 safety diesels.

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2 (4) Personnel Training

3 Personnel training will be conducted by

4 HL&P to insure that maintenance personnel are cognizant

5 of the prescribed maintenance procedures.

6 B. Significant Corrective Action

7 (1-2) Pre-Lube

8 This section recommends a pre-lube period of

9 3 to 5 minutes for all non-emergency starts. For emer-

10 gency starts, it is recommended that the engine pre-lube

11 be started by the same signal which initiates the cranking

12 of the engine.

13 The Allens Creek design (for all three safety

14 diesels) incorporates a continuous lube oil circulating

15 system which eliminates the need for a pre-lube period. For

16 the HPCS diesel generator there are two AC powered motor

17 driven lube oil pumps. One pump is dedicated to keeping

18 the turbocharger bearings lubricated while the other is

19 dedicated to keeping the filter / cooler rack full and the

20 main engine bearings pre-lubed.

21 For the Division 1 and Division 2 safety

22 diesels, the continuous lube oil system has a small AC

28 motor driven pre-lube pump designed to keep the cylinder

24 head rocker assembly lubricated when the engine is shut-

25 down and a larger AC motor driven pump which provides

26 continuous pre-lubrication at keep-warm temperature

27 to the rest of the engine and keeps all external

28 systems full.

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2 (3) Testing, Test Loading and PreventiveMaintenance

All testing procedures and preventive main-4

tenance procedures to be utilized for the diesel

generators will be formulated in accordance withthe NRC and the manufacturer's specific recommendations.

7(4) " Root Cause" and Correction Action

This section deals specifically with theg

identification of the real reason, i.e., " root cause"

of any engine / generator malfunction. HL&P operating

personnel will be trained to determine and correct theg" root cause" of diesel generator malfunctions.

C. Additional Corrective Action

(1) DG Room Ventilation & Combustion Air Inletsg(a) Recommendations discussed below reduceg

the amount of dust / contaminants in and around the diesel.pIn accordance with recommendation C.la of NUREG/CR-0660,g

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combustion air is extracted from the outside at angelevation 35 feet above the finished floor, filteredgand then ducted directly to the diesel generator air

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intake.g(b) As noted in Item A-2, C.lb of NUREG/CR-g

0660 is addressed as follows: room ventilation is takengin at a level starting 3 1/2 feet above grade (Elev.g142'6") up to an elevation of 173 ft. This arrange-gment is necessary to provide adequate surface area ofglouvers so as to control the maximum room temperature.g

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2 (c) In accordance with recommendation C.lc

3, of MUREG/OR-0660, room ventilation air and engine exhaust:

4'- gases are expelled directly to the atmosphere.

5 (2) Fuel Storage Bui.lding

6 As recommended by NUREG/CR-0660, the ACNGS bulk

7' fuel tanks have a gravity drain from the bottom of the

S tank for pumping out accumulated water. Fuel transferj

! to each of the diesel engine day tanks from the bulk fuel9

10 tanks is provided by gravity flow.

11 (3) High Temperature Insulation for Overload

12 In order to protect the generator against

13 overheating in an overload condition, NUREG/CR-0660

14 recommends, as a criteria, that the generator electrical

15 insulation be able to withstand a 105'C rise over a 40*C

16 timbient, for a maximum temperature of 145*C.

17 Each of the three diesel generators has a

18 Class F electrical insulation which is rated for a 105*C

19 rise over a 40*C ambient. The generators are limited to a

20 80*C rise over a 50*C ambient; yielding a 15'C margin.

21 The amount of margin in the HPCS and Divisions

22 1 and 2 is sufficient for the following reasons:

23 (a) The HPCS DG is connected to only one

24 large load, the HPCS pump motor. The DG

25 will be qualified to power that load under

26 emergency conditions. Therefore, there is

27 no potential for extended overload of the

28 diesel generator.

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2 (b) The continuous rating for the Divisions

3 1 and 2 safety diesel generators is 110% of the

4 continuous rating of the Divisions 1 and 2

5 diesel engines. This combined with the

6 margin already incorporated in the insulation

7 design eliminates the possibility of overheating

8 the generator durino the postulated engine

9 overload condition.

10 (4) Engine Cooling Water Temperature Control

11 In accordance with recommendation C.4 of NUREG/

12 CR-0660, the ACNGS diesels accomplish cooling water

13 temperature control by means of a 3-way thermostat for

14 directing the water to 5 , ass the cooler or to the

15 cooler as required.

16 (5) Concrete Flcors - Painting

17 In accordance with recommendation C.5 of NUREG/

18 CR-0660, the diesel generator building floors will be

19 painted to minimize concrete dust accumulation that might

20 interfere with devices which are part of diesel generator

21 system and which depend on electrical contacts.

22 (6) Instrumentation and Controls or MonitoringElements - Mounting and Supports

23The location of engine / generator control

panels will be as specified by the manufacturer. To the

extent functionally practical, sensing instruments and

control or monitoring elements will be on free standing,

floor mounted panels in accordance with recommendation

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2 C.6 of NUREG/CR-0660.

3 Q. Mr. Clarke, please describe HL&P's evaluation of Inspection

4 and Enforcement Circular No. 79-12.

5 A. On January 28, 1979, the NRC Office of Inspection and

6 Enforcement issued an Inspection and Enforcement Circular

7 No. 79-12 titled " Potential Diesel Generator Turbocharger

8 Problem". In this IE circular the NRC identified a9 potential failure of the turbocharger en diesels manu-

f10 factured by the Electro-Motive Division (EMD) of the

11 General Motors Corporation.

12 The problem that was cited occurred if the diesel

13 engine received a repeated rapid start within a 15 minute

14 to 3 hour time period after a shutdown from a previous run

15 in which the engine had reached operating temperature.

16 During normal standby the flow from the circulating

17 oil pump is divided via a 30 psi spring loaded check valve

18 into separate flows to the turbocharger bearings and to

19 the accessory rack. This flow split keeps the turbo-

20 charger bearings prelubed and the accessory rack filled

21 and primed for a fast start. However, when the oil is

22 hot, insufficient oil pressure is generated to accomplish

23 the flow split. As a result all the circulating oil is

24 supplied to the turbocharger bearings and the ac-25 cessory rack partially drains. Upon restart the engine

26 driven scavenger pump must first fill the accessory rack

27 before oil can be supplied to the main engine oil sump.

28 This temporary loss of main engine oil pressure can

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2 result in cumulative damage to the turbocharger hearings.

3 The Allens Creek HPCS diesel is manufactured by

4 EMD. However, the Allens Creek design utilizes two in-

5 dependent flow paths, each with its own pump. One pump

6 supplies the turbocharger bearings and the other pump

7 supplies the accessory rack. With this arrangement, the lube

8 oil system will retuain primed and ready for a restart and

9 the 15 minute to 3 hour restriction will be eliminated.

10 Q. Describe HL&P's evaluation of Inspection and Enforcement

11 Information Notice No. 79-23.

12 A. On February 26, 1979, the NRC Office of Inspection and

13 Enforcement issued Inspection and Enforcement Notice No.

14 79-23 titled " Emergency Diesel Generator Lube Oil Coolers".

15 This notice reported the failure of tube sheets in lube

16 oil coolers of diesels manufactured by the Electro-Motive

17 Division of General Motors. The failed tube sheets were

18 1/8" thick and had soldered joints. Corrosion of the

19 soldered joints caused the failures. The tube sheets

20 used on the Allens Creek HPCS diesel generator are

21 jointed by a rolling process and are 1/2" thick. The

J 22 increased thickness and the elimination of the soldered

23 joint will preclude this problem on ACNGS.

24 Q. What are your conclusions?

25 A. Improvements in the design of the diesel generators

26 systems have been made to address NUREG/CR-0660 and

27 various I&E Bulletins. These design improvement will

28 ensure high reliability for the ACNGS diesel generators.

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1 Exhibit RAC-1.

2! EDUCATION AND PROFESSIONAL QUALIFICATIONS

3 Richard A. Clarke

4 Mr. Clarke is currently a Senior Engineer in the Systems

5 Engineering Section of the Nuclear Control and Instrumentation

6 Department of the Nuclear Energy Business Group of the General

7' Electri c Company. In this capacity, Mr. Clarke is assigned

8 the task of providing follow-up engineering and licensing

9 services as required to support General Electric contracts,

10 in the area of the HPCS system. Previously, Mr. Clarke was

11 the Lead Engineer in charge of Electronic Design of a Solid

12 State Protection System for a BWR nuclear plant. Past

13 experience also includes etart-up work on five nuclear

14 plants and includes work on several standby diesel generator

15 power systems.

16 Mr. Clarke has twelve years of power plant engineering

17 experience, and a BS Degree in Electrical Engineering from

18 the University of Santa Clara (1969).

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1 EXHIBIT JFM-1EDUCATION 7?iD PROFESSIONAL QUALIFICATIONS*

2|- JOSEPH F. MONTALBANO8

4' EXPERIENCE SUMMARY

Registered Professional Engineer with nine years of5|6|

experience in electrical design engineering of fossil-and

7 nuclear-fueled electric generating stations. Responsibilities

8 included developing the electrical system and basic design

9 criteria for each project, application of computer analyses

10 for an optimum electrical auxiliary system, develop:cnt of

11 electrical main and auxiliary one-line diagrams, input

12 criteria fo' physical design drawings for the station,

13 economic analysis of equipment options, preparation of

14 equipment specifications, purchase requisitions, bid evaluations

15 and recommendations for purchase, surveillance of equipment

16 orders for compliance with specification and required-at-site

17 dates, and engineering support to field forces.

18 Administrative responsibilities have included project

19 implementation of OA Programs, development of CPM logic and

20 manpower forecasts and resources and exercising job control

21 by monitoring schedule and workday and Earned Value reports.

22 Responsible for distribution system design for 5 kV

23 and 13 kV underground networks including conductor selection,

24 cable and transformer selection and location and impedance

25 calculations.

26 EMPLOYMENT HISTORY

27 Ebasco Services Incorporated, New York, New York;

28 1972 - Present

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Supervising Engineer, 1981-Present2 *

h3' Principal Engineer, 1980-1981*

Senior Engineer, 1977-19804 *

Engineer, 1975-19775.. *

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Associate Engineer, 1974-19756 *

fAssistant Engineer, 1972-19747 *

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8I EDUCATION

9|. Polytechnic Institute of Brooklyn-BSEE-1972l *

10 'Polytechaic Institute of New York-MSEE-1977*

11 New York Institute of Technology-MBA-1981*

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13 REGISTRATIONS

14 Professional Engineer in the States of New York

15 and New Jersey.

16PROFESSIONAL AFFILIATIONS

17IEEE-Member

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