ML19347F524

Testimony of RA Clarke & Jf Montalbano Re Doherty Contention 10,diesel Generator Reliability.Prof Qualifications Encl. Related Correspondence

ML19347F524
Person / Time
Site:	Allens Creek File:Houston Lighting and Power Company icon.png
Issue date:	05/11/1981
From:	Clark R, Montalbano J EBASCO SERVICES, INC., GENERAL ELECTRIC CO.
To:
Shared Package
ML19347F516	List: ML19347F515 ML19347F520 ML19347F522 ML19347F524 ML19347F527 ML19347F529 ML19347F530 ML19347F531 ML19347F532 ML19347F534 ML19347F535 ML19347F536 ML19347F537 ML19347F539
References
NUDOCS 8105190526
Download: ML19347F524 (14)

Text

May 11, 1981 p 4 RELATED CORRESPONDENCE 1 'INITED STATES OF AMERICA ff cocwd b M*U

'- in CLEAR REGULATORY COMMISSION

'y 2 op MAY 13 gggg y y 3 BEFORE TriE ATOMIC SAFETY AND LICENSING BOARD 4

6 %7 z N

5 In the Matter of )

)

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

)

7 (Allens Creek Nuclear Generating )

Station, Unit No. 1) )

8: )

9 TESTIMONY OF RICHARD A. CLARKE AND 10- JOSEPH F. MONTALBANO ON BEHALF OF HOUSTON LIGHTING & POWER COMPANY 11 ON DOHF'_Y CONTENTION 10 -

DIESEL GENERATOR RELIABILITY 12 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 810519a 626

, 1 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

C 1 .

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, l

l 25 thereby lowering the temperature at which the remaining 26 water in the compressed air will condense. Regenerative i 27 dessicant dryers are currently specified for use in the 28 air starting systems of all three Allens Creek safety l

I

, 1 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

1, '

2l' 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-6l tion which are extremely restrictive, or by upgrading 7l 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 hours0.0231 days <br />0.556 hours <br />0.00331 weeks <br />7.61e-4 months <br /> accumulative time at less 15 than 20% of rated load; 16 (b) 4000 hours0.0463 days <br />1.111 hours <br />0.00661 weeks <br />0.00152 months <br /> 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.

28

. 1 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.

, 1 _7_

2 (3) Testing, Test Loading and Preventive Maintenance All testing procedures and preventive main-4 tenance procedures to be utilized for the diesel generators will be formulated in accordance with the NRC and the manufacturer's specific recommendations.

7 (4) " Root Cause" and Correction Action This section deals specifically with the g

identification of the real reason, i.e., " root cause" of any engine / generator malfunction. HL&P operating g personnel will be trained to determine and correct the

" root cause" of diesel generator malfunctions.

C. Additional Corrective Action g (1) DG Room Ventilation & Combustion Air Inlets g (a) Recommendations discussed below reduce p the amount of dust / contaminants in and around the diesel.

In accordance with recommendation C.la of NUREG/CR-0660, 4

g g combustion air is extracted from the outside at an elevation 35 feet above the finished floor, filtered g

and then ducted directly to the diesel generator air 21 g intake.

g (b) As noted in Item A-2, C.lb of NUREG/CR-g 0660 is addressed as follows: room ventilation is taken in at a level starting 3 1/2 feet above grade (Elev.

g 142'6") up to an elevation of 173 ft. This arrange-g g ment is necessary to provide adequate surface area of louvers so as to control the maximum room temperature.

g 1

1 t 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 Sj tank for pumping out accumulated water. Fuel transfer 9! to each of the diesel engine day tanks from the bulk fuel 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.

1 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 Monitoring Elements - Mounting and Supports 23 The 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

1 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 a 9 potential failure of the turbocharger en diesels manu-f 10 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 hour3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> 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

o 1 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 hour3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> 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.

i

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).

19 20 21 22 2h 24 25 26 27 28

1 EXHIBIT JFM-1

• EDUCATION 7?iD PROFESSIONAL QUALIFICATIONS 2l-8 JOSEPH F. MONTALBANO 4' EXPERIENCE

SUMMARY

Registered Professional Engineer with nine years of 5l experience in electrical design engineering of fossil-and 6l nuclear-fueled electric generating stations. Responsibilities 7

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

i i

O 1 2

• Supervising Engineer, 1981-Present h

3'

• Principal Engineer, 1980-1981 4

• Senior Engineer, 1977-1980 5..

• Engineer, 1975-1977 6

li

• Associate Engineer, 1974-1975 f

7

• Assistant Engineer, 1972-1974 p;

8 I EDUCATION 9l. l

• Polytechnic Institute of Brooklyn-BSEE-1972 10 '

• Polytechaic Institute of New York-MSEE-1977 11

• New York Institute of Technology-MBA-1981 12 13 REGISTRATIONS 14 Professional Engineer in the States of New York 15 and New Jersey.

16 PROFESSIONAL AFFILIATIONS 17 IEEE-Member 18 19 20 21 22 23 24 25 26 27 28

.. . - - . . - _ -. . - - - - -