ML18081B064
| ML18081B064 | |
| Person / Time | |
|---|---|
| Site: | Salem  |
| Issue date: | 02/14/1980 |
| From: | Mittl R Public Service Enterprise Group |
| To: | Parr O Office of Nuclear Reactor Regulation |
| References | |
| RTR-NUREG-0660, RTR-NUREG-660 NUDOCS 8002200453 | |
| Download: ML18081B064 (21) | |
Text
i',.
Public Service Electric and Gas Company 80 Park Place Newark, N.J. 07101 Phone 201/430-7000 February 14~ 1980 Director of Nuclear Reactor Regulation
- u. S. Nuclear Regulatory Commission Washington, D. c.
20555 Attn:
Mr. Olan D. Parr, Chief Light Water Reactors Branch 3 Division of Project Management Gentlemen~
RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION EMERGENCY DIESEL-GENERATOR RELIABILITY NO. 2 UNIT SALEM NUCLEAR GENERATING STATION DOCKET NO. 50-311 PSE&G hereby submits its response to your request for addit-ional information concerning implementation of the recommen-dations of NUREG-0660, "Enhancement of On Site Emergency Diesel-Generator Reliability", dated December 14, 1979.
Should you have any further questions in this regard, please do not hesitate to contact us.
Attachment HR3 The Energy People Very truly yours, r-1~--
R. L. Mittl General Manager -
Licensing and Environment Engineering and Construction 95-0942
4-.
Q8.l A8.l REQUEST FOR ADDITIONAL INFORMATION SALEM NUCLEAR GENERATING STATION,* UNIT 2 DOCKET NO. 50-311 Provide a discussion of the measures that have been taken in the design of the standby diesel generator air starting system to preclude the fouling of the air start valve or filter with moisture and contaminants such as oil carryover and rust (SRP 9.5.6, Part III, Item 1).
Air dryers in the starting air system lower the atmos-phere dew point to -lQOOF.
Filters are also included in this system which will remove contaminants such as oil carryover and rust.
M P80 7 15/1
Q8.2 REQUEST FOR ADDITIONAL INFORMATION SALEM NUCLEAR GENERATING STATION, UNIT 2 DOCKET NO. 50-311 Experi~nce at some operating plants has shown that diesel engines have failed to start due to accumula-tion of dust and othr deleterious material on electri-cal equipment associated with starting of the diesel generators (e.g., auxiliary relay contacts, control switches - etc.)
Describe the provisions that have been made in your diesel generator building design, electrical starting system; combustion air and venti-lation air intake design(s) to preclude this condition to assure availability of the diese.l generator on*
demand.
Also describe, under normal plant operation, what pro-cedure(s) will be used to minimize accumulation of dust in the Diesel Generator Room~ specifically address concrete dust control.
In your response also consider the condition when Unit is in operation and' Unit 2 is under construction (Abnormal generation of dust).
A.8.2 The building where the emergency diesel generators are located is compartmentalized such that the electrical equipment is located in a separate compartment from the emergency diesel generators.
This arrangement assures the proper operation of the electronic equip-ment in the starting system.
Also, the control equip-ment and instrumentation are located in cabinets which minimize the accumulation of dust on the relay con-tacts, control switches, etc.
The intake and exhaust combustion air is ducted from the outside of the building.
This precludes any con-tamination of the Diesel Generator Room atmosphere with deleterious materials.
The ventilation system design is a once through system with both intake and exhaust from the outside of the Emergency Diesel Generator Room.
The ventilation system inlet and exhaust ducts are located approxi-mately 30' and 50' above ground level, respec~ively, to minimize the amount of dust collected by the ven-tilation system.
M P80 7 15/2 The condition described whereby abnormal generation of dust from Unit No. 2 which is under construction affecting the operation.of the Unit No. 1 is not possi-ble.
The Emergency Diesel Generator Rooms for each unit are separate and distinct and have no common corridor between the two.
M PBO 7 15/3
Q8.3 A8.3 REQUEST FOR ADDITIONAL INFORMATION SALEM NUCLEAR GENERATING STATION, UNIT 2 DOCKET NO. 50-311 The diesel generators are required to start automati-cally on loss of all off-site power* and in the event of a LOCA.
The diesel generator sets should be capa-ble of operation at less than full load for extended periods without degradation of performance or reli-ability.
Should a LOCA occur with availability of off-site power, discuss design provisions and other para-meters that have been considered in the selection of the diesel generators to enable them to run unloaded (on standby) for extended periods without degradation of engine performance or reliab*ility.
Expand your PSAR/FSAR to include and explicitly define the capa-bility of your design with regard to this requirement (SRP 9.5.5, Part III, Item 7).
The emergency diesel generators are designed to run unloaded for up to one week without degradation of engine performance or reliability.
M P80 7 15/4
Q8.4 AB.4 REQUEST FOR ADDITIONAL INFORMATION SALEM NUCLEAR GENERATING STATION, UNIT 2 DOCKET NO. 50-311 Section 9.5.4.1 emergency diesel engine fuel oil storage and transfer system (EDEFSS) does not specifi-cally reference ANSI Standard Nl95 "Fuel Oil Systems for Standby Diesel Generators".
Indicate if you in-tend to comply with this standard in your design of the EDEFSS; otherwise, provide justification for non-compliance (SRP 9.5.4, Ref. 1, Part II, Item 12).
The emergency diesel engine fuel oil storage and transfer system is installed.
It complies generally with ANSI Nl95.
Differences exist between the codes specified in the standard for the equipment.
ln many cases these differences can be attributed to the fact that some of the codes specified in the standard did not exist at the time of equipment manufacture.
The equipment installed, although not built to these newer codes, is of acceptable quality for use in an emer-gency diesel generator system.
M PBO 7 15/5
Q8.5 A8.5 REQUEST FOR ADDITIONAL INFORMATION SALEM NUCLEAR GENERATING STATION, UNIT 2 DOCKET NO. 50-311 Assume an unlikely event has o~curred requiring opera-tion of a diesel generator for a prolonged period that would require replenishment of fuel oil interrupting operation for the diesel generator.
What provision will be made in the design of the fuel oil storage fuel system to minimize the creation of turbulence of sediment in the bottom of the storage tank?
Stirring of the sediment during addition of new fuel has the potential of causing the overall quality of fuel to become unacceptable and could potentially lead to the degradation or failure of the diesel generator.
The location of the fuel oil inlet to the fuel oil storage tanks is approximately 50' of horizontal distance away from the fuel oil storage tank outlet connection to the fuel oil day tanks.
This distance is sufficient to preclude turbulence inside the fuel oil storage tanks during filling such as to dislodge sediment or other accumulations 50' away at the dis-charge connection from the tank.,Strainers located downstream of the tank will collect any loose sedimen-tation or other undesirable elements.
M P80 7 15/6
Q8.6 AS.6 REQUEST FOR ADDITIONAL INFORMATION SALEM NUCLEAR GENERATING STATION, UNIT 2 DOCKET NO. 50-311 Discuss the precautionary measures that will be taken to assure the quality and reliability of the fu~l oil supply for emergency diesel generator operation.
Include the type of fuel oil, impurities and quality limitations as well as diesel index number or its equivalent, cloud point, entrained moisture, sulfur particulates and other deleterious insoluble sub-stances~ procedure for testing newly delivered fuel, periodic ~ampling and testing of on-site fuel oil (interval between tests) interval of time between periodic removal of condensate from fuel tanks and periodic system inspection.
In your discussion, include reference to industry (or other) standard which will be followed to assure a reliable fuel oil supply to the emergency generators (SRP 9.5.4, Part III, Items 3 and 4).
Surveillance requirements to ensure the qual~ty and reliability of the fuel oil supply for the emergency diesel generators are stipulated in the Technical Specifications.
Periodic sampling and testing of on-site fuel oil is "performed at least once per ninety-two days to verify that a sample of diesel fuel from each of the 20,000 gallon fuel oil storage tanks is within the acceptable limits specified in Taqle 1 of ASTM D975-68 when checked for viscosity, water and sediment.
M PBO 7 15/7
Q8.7 REQUEST FOR ADDITIONAL INFORMATION SALEM NUCLEAR GENERATING STATION, UNIT 2 DOCKET NO. 50-311 Operating experience has shown that the accumulation of water in the starting air system has been one of the most frequent causes of diesel engine failure to start on demand.
Condensation of entrained moisture in.compressed air lines leading to control and start-ing air valves, the air start motors, and condensation of moisture on the working surfaces of these com-ponents has caused rust, scale and water itself to build up and score and jam the internal working parts of these vital components thereby preventing starting of the diesel generators.*
In the event of loss of off-site power the diesel generators must function since they are vital to the safe shutdown of the reactor(s).
Failure of the diesel generators to start from the affects of mositure condensation in air starting systems and from other causes have lo~ered their operational reliabil-ity to substantially last less than the desired relia-bility of 0.99 as specified in Branch Technical ICSB (PSB) 2 "Diesel Generator Reliability Testing" and Regulatory Guide 1.108 "Periodic Testing of Diesel Generator Units Used as Onsite Electric Power Systems at Nuclear Power Plants".
In an effort toward improving diesel engine starting reliability, NUREG-0660 indicates that compressed air starting system designs include air dryers for the removal of entrained moisture.
The two air dryers most commonly used are the dessicant and refrigerant types.
Of these two types, the refrigerant type is the most suited for this application and, therefore, is preferred.
Starting air should be dried to a dew point not more that 500F when installed in a normally controlled 70° environment, otherwise the starting air dew point should be controlled to at least 10°F less than the lowest expected ambient temperature.
Describe your diesel engine air starting system and indicate how your system meets the recommendation stated in NUREG-0660.
If there are any differences between your design and recommendations of NUREG-0060, provide justification of your design for plans for implementation.
M P80 7 15/8
A8.7
- The starting air system for the emergency diesel generators is provided with dessicant type heaters.
These dessicant heaters are designed to dry air to an atmospheric dew point of -
lQQOF.
This provision meets or exceeds the requirements of NUREG 0660.
M P80 7 15/9
Q8.8 REQUEST FOR ADDITIONAL INFORMATION SALEM NUCLEAR GENERATING STATION, UNIT 2 DOCKET NO. 50-311 Operating experience at certain nuclear power plants which have two cycle turbo charged diesel engines manufactured by Electromotive Division (EMD) of General Motors driving emergency generators have ex-perienced a significant number of.turbocharger mechan-ical gear drive failures.
The failures have occurred as a result of running the emergency diesel generators at no load or light load conditions for extended periods.
No load or light load operations could occur during periodic equipment testing or during accident conditions with availability of off-site power.
When this equipment is operated under no load conditions, insufficient exhaust gas volume is generated to operate the turbocharger.
As a result, the turbo-charger is driven mechanically from the gear drive in order to supply enough combustion air to the engine to maintain rated speed.
The turbocharger and mechanical drive gear normally supplied with these engines are not designed for standby service encountered in nuclear power plant application where the equipment may be called upon to operate at no load or light load condition and full rated speed.for a prolonged period.
The EMD equipment was originally designed for locomo-tive service where no load speeds for the engine and generator are much lower than full load speeds.
The locomotive turbocharged diesel hardly ever runs at full speed except at full load.
The EMD has strongly recommended to users of this diesel engine design against operation at no load or light load condition at full rated speed for extended periods because of the short life expectancy of the turbocharger mechan-ical gear drive unit normally furnished.
No load or light load operation also causes general deterioration in any diesel engine.
To cope with the severe service the equipment is normally subjected to and in the interest of reducing failures and increasing the availability of their equipment, EMD has developed a heavy duty turbocharger drive gear unit that can replace existing equipment.
This is available as a replacement kit, or engines can be ordered with the heavy duty turbocharger drive gear assembly.
M PBO 7 15/10
A8.8
- To assure optimum availability of emergency diesel generators on demand, applicants who have on order or intend to order emergency generators driven by two cycle diesel engines manufactured by EMD should be provided with the heavy.duty turbocharger mechanical drive gear assembly as recommended by EMD, for the class of service encountered in nuclear power plants.
Confirm your compliance with this requi~ement.
The turbocharged diesel engines were manufactured by Alco Engine Division of White Motor Company.
In the Alco design, the turbocharger is a free spinning device which does not require the same type of arrangement as the General Motors design.
M P80 7 15/11
Q8.9 AB.9 REQUEST FOR ADDITIONAL INFORMATION SALEM NUCLEAR GENERATING STATION, UNIT 2 DOCKET NO. 50-311 Provide a detail discussion (or plan) of the level of training proposed for your operators, maintenance crew, quality assurance, and supervisory personnel responsible for the operation and maintenance of the emergency diesel. generators.
Identify the number and type of personnel that will be dedicated to the operations and maintenance of the emergency diesel generators and the number and type that will be assigned from your general plant operations and maintenance groups to assist when needed.
In your discussion identify the.amount and kind of training that will be received by each of the above categories and the type of ongoing training program planned to assure optimum availability of the emergency generators.
Also discuss the level of education and minimum ex-perience requirements for the various categories of operations and* maintenance personnel associated with the emergency diesel generators.
Current training of personnel in the various disci-plines required to assure optimum operability of the Emergency Diesel Generators is as follows:
Operations
- 1.
Shift Supervision..*. receive, in the course of licensing for NRC, detailed functional and opertional instruction Qn the emergency diesel generators and associated support systems and controls.
This occurs in both the initial and re-qualification (on-going) training as required by NRC.
- 2.
Shift Control Operators ***. in addition to training similar to supervisory training (above), CO'.s have gone through the phase training received by the equipment operators as stated below.
- 3.
Equipment Operators **** receive Phase I and II training at corporate training facilities which provides non-equipment-specific training which en-hances skills required for all equipment M P80 7 15/12 operation.
On the job training and individual check outs on the emergency diesel generators by shift supervision completes the E.O.'s training on the equipment.
Maintenance
- 1.
Maintenance Supervision...* have mostly received skills training and on-the-job experience while assigned to maintenance gangs as non-supervisory employees (below).
- 2.
Maintenance Personnel ***. receive skills training at a 3 month intermediate skills training course at corporate training facilities and 3 months on the job training at the station prior to assuming productive assignments.
Quality Assurance Receive 3 week -
Level II "Verifier" training by Corporate QA Department in which personnel are indoc-trinated in Quality Program Fundamentals.
Currently they accompany Operating Department personnel to become familiar with equipment and operational methods.
This training provides adequate assurance that the operators and maintennce staff can maintain the emergency diesel generators in an optimum state of operability.
There are no special groups or individuals in the Ope~ating and Maintenance Departments dedicated solely to the Emergency Diesel Generators.
All personnel in these departments are used as necessary in accordance with ANSI/ANS 3.1-1978 and 10CFR55 requirements as applicable.
Station supervisory personnel associated with the Emergency Diesel Generat.ors meet or exceed the requirements of ANSI-Nl8.l.
M PSO 7 15/13
REQUEST FOR ADDITIONAL INFORMATION SALEM NUCLEAR GENERATING STATION, UNIT 2 DOCKET NO. 50-311 Q8.10 Several fires have occurred at some operating plants in the area of diesel engin.e exhaust *manifold and inside the turbocharger housing which have resulted in equipment unavailability.
The fires were started from lube oil leaking and accumulating on the engine exhaust manifold and accumulating and igniting inside the turbocharger housing.
Accumulation of lube oil in these areas, on some engines, is apparently caused from an excessively long prelube period, generally longer than five minutes, prior to manual starting of a diesel generator.
This condition does not occur on an emergency start since the prelube is minimal.
When manually starting the diesel generators for any reason, to minimize the potential fire hazard and improve equipment availability, NUREG-0660 recommends that the prelube period should be limited to a maximum to three to five minutes unless otherwise recommended by the diesel engine manufacturer.
Provide the prelube time interval your diesel engine will be exposed to prior to manual start and if this interval does not agree with the recommendations of NUREG 0660 to provide justification why your interval time is acceptable.
A8.10 The design of the turbochargers on the emergency diesel engines is such that prelube is not required.
Lubrication of the turbochargers start_s only after the diesels have attained a lube oil pressure higher than the prelube oil pressure.
M P80 7 15/14
REQUEST FOR ADDITIONAL INFORMATION SALEM NUCLEAR GENERATING STATION, UNIT 2 DOCKET NO. 50-311 Q8.11 An _emergency diesel generator unit in a nuclear power plant is normal in the ready standby mode unless there is a loss of offsite power, an accident, or a diesel generator is under test.
Long periods on standby have a tendency to drain or nearly empty the engine lube oil piping system.
On an emergency start of the engine as much as five to fourteen or more seconds may lapse from the start of cranking until full lube oil pressure is obtained even though full engine s.peed is generally reached in about five seconds.
With an essentially dry engine, the momentary lack of lubrica-tion at various moving parts may damage bearing sur-faces producing incipient or actual component failure with resultant equipment unavailability.
The emergency condition of readiness requires this equipment to obtain full rated speed and enable auto-
. matic sequencing of electric load within ten seconds.
For this reason, and to improve upon availability of this equipment on demand, it is necessary to establish as quickly as possible an oil film in the wearing parts of the diesel engine.
Lubricating oil is normally delivered to the engine wearing parts by one or more engine driven pump(s).
During the starting cylce the pump(s) accelerates slowly with the engine and may not supply the required quantity of lubricat-ing oil where it is needed fast enough.
To remedy this condition as a minimum, electrically driven lubricating pump, powered from a reliable DC power supply, should be installed in the lube oil system to operate in parallel with the engine drive main lube pump.
The electric driven prelube pump should operate only during the engine cranking cycle or until satis-factory lube oil pressure is established in the engine main lube distribution header.
The installation of this prelube pump should be coordinated with the respective engine manufacturer.
Some diesel engines include a lube oil circulating pump as a integral part of the lube oil preheating system which in use while the diesel engine is in a standby mode.
In this case an additional prelube oil pump may not be needed.
M P80 7 15/15
~* Indicate whether your design includes an electric pre-1 ube oil pump.
If your design does not include this pump, provide justification why it is not necessary.
A8.ll An electrically driven prelube oil pump in parallel with the engine driven main lube pump is installed on each of the Diesel Generators.
This pump is powered from a vital AC source and operates continuously to maintain the required lube oil header pressure when-ever the diesels are not operating.
An alarm is provided in the Control Room for immediate detection of any malfunction in the lube oil system including prelube pump failure.
M P80 7 15/16.
REQUEST FOR ADDITIONAL INFORMATION SALEM NUCLEAR GENERATING STATION, UNIT 2 DOCKET NO. 50-311 Q8.12 Periodic testing and test loading of an emergency diesel generator in a nuclear power plant is a necessary function to demonstrate the operability, capability and availability of the unit on demand.
Periodic testing coupled with good.preventative main-tenance practices will assure optimum equipment readi-ness and availability on demand.
This is the desired goal.
To achieve this optimum equipment readiness status, NUREG 0660 recommends the following:
- 1.
The equipment should be tested with a minimum of 25% of rated load.
No load or light load operation will cause incomplete combustion of fuel resulting in the formation of gum and varnish deposits on the cylinder ~alls, intake and exhaust valves, piston rings, etc., and accumulation of unburned fuel in the turbocharger and exhaust system.
The consequences of no load or light load operation of potential equipment due to the gum and varnish deposits and fire in the engine ex-haust system.
- 2.
Periodic surveillance testing should be performed in accordance with applicable NRC Guidelines (RG 1.108), and with the recommendations of the engine manufacturer.
Conflicts between any such recommendations and the NRC guidelines, particu-larly with respect to test frequency, loading and duration, should be identified and justified.
- 3.
Preventive maintenance should go beyond the normal routine adjustments, servicing and repair of com-ponents when a malfunction occurs.
Preventive
-maintenance should encompass investigative testing of components which have a history of repeated malfunctioning and require constant attention and repair.
In such cases consideration should be given to replacement of those components with other products which have a record of demonstrated reliability rather than repair and maintenance of existing components.
Testing of the unit after adjustments or repa~rs have been made, only con-firms that the equipment is operable and does not necessarily mean that the root cause of the problem has been eliminated or alleviated.
M P80 7 15/17
~* 4.
Upon completion of repairs for maintenance and prior to a actual start run and load test, a final equipment check should be made to assure that all electrical circuits are functional, i.e., fuses are in places, switches and circuit breakers are in their proper position, no loose wires, all test leads have been removed, and all valves are in the proper position to permit a manual start of the equipment.
After the unit has been satisfactorily started and load tested, return the unit to ready automatic standby service and under the control of the Control R?om Operator.
Provide a discussion of whether the recommendations of NUREG-0060 have been implemented in the emergency diesel generator system design and how they will be considered when the plant is in commercial operation i.e., by what means will the above requirements be en-forced?
A8.12 Compliance with the recommendations of NUREG 0660*is described below.
- 1.
The Technical Specifications define the periodic testing to be performed on the Emergency Diesel Generators.
Periodic testing is performed with a minimum of 25% of rated load.
- 2.
Please refer to our response to question 13.9 (c) in our February 5, 1979 submittal regarding com-pliance to RG 1.108.
- 3.
During normal routine adjustments, servicing and repair of components when a_malfunction occurs, components with a history of repeated failures are brought to the attention of the Engineering Department for investigation and possible substi-tution with more reliable components.
- 4.
Upon completion of repairs, the.diesel generators are returned to operational readiness in accord-ance with station procedures which require that the equipment be returned to operating readiness status.
M P80 7 15/18 _
REQUEST FOR ADDITIONAL INFORMATION SALEM NUCLEAR GENERATING STATION, UNIT 2 DOCKET NO. 50-311 Q8.13 The availability on demand of an emergency diesel generator is dependent-upon, among other things, the proper functioning of its controls and monitoring instrumentation.
This equipment is generally panel mounted and in some instances the panels are mounted directly on the diese.l generator skid.
Major diesel engine damage has occurred at some operating plants from vibration induced wear on skid mounted control and monitoring instrumentation.
The sensitive instru-mentation is not made to withstand and funciton accurately for prolonged. periods under continuous vibrational stresses normally encountered with in-ternal combustion engines.
Operation of sensitive instrumentation under this environment rapidly deteriorates calibration, accuracy and control signal output.
Therefore, except for sensors* and other equipment that may be directly mounted on the engine or associated piping, NUREG 0660 recommends that the controls and monitoring instrumentation be installed on a free standing floor mounted panel separate form the engine skids and located on a vibration free floor area or equipped with vibration mounts.
Provide a description of how the controls and monitor-ing systems are installed and indicate how your design addresses the recommendations of NUREG 0660.
AB.13 The controls and monitoring instrumentation panels for*
the emergency diesel generators are located in a separate room from the emergency diesel generators.
Because of the isolation of this instrumentation from the emergency diesel generators, no damage can occur to the instruments as a result of vibration from the diesel generators.
M PBO 7 15/19
REQUEST FOR ADDITIONAL INFORMATION SALEM NUCLEAR GENERATING STATION, UNIT 2 DOCKET NO. 50-311 Q8.14 Experience at operating plants has shown that a diesel engine that is provided with an eng~ne cooling water temperature control system employing a three-way bypass-type thermostatically controlled valve has demonstrated consistent trouble free operation over engines provided with other methods of temperature control such as shutter controls on radiators.
Does our system employ a water thermostat of the three-way or bypass-type which puts the water flow so only as much water passes through ~he cooler or radiator as needed to maintain the proper temperature?
If your engine cooling system does not use a three-way valve describe your installed system and justify its design as opposed to a design employing a three-way valve.
AB.14 The emergency diesel generators employ a three-way valve to divert water to the cooler in order to main-tain the proper outlet temperature.
M PBO 7 15/20