ML20237L665

Draft Summary of Seismic Adequacy of Twenty Classes of Equipment Required for Safe Shutdown of Nuclear Plants

ML20237L665
Person / Time
Site:	Sequoyah
Issue date:	02/28/1987
From:	Hardy G, Horstman N, Swan S SEISMIC QUALIFICATION UTILITY GROUP
To:
Shared Package
ML20237L651	List: ML20237L647 ML20237L665
References
NUDOCS 8708200295
Download: ML20237L665 (9)

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SUMMARY

OF THE SEISMIC ADEQUACY OF l

. TWENTY CLASSES OF EQUIPMENT REQUIRED FOR p THE SAFE SHUTDOWN OF NUCLEAR PLANTS February 1987 I

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). Prepared by:

Nancy G. Horstman l

Sam W. Swan Greg S. Hardy Prepared for:

THE SEISMIC QUALIFICATION UTILITY GROUP 801 18th Street, N.S., Suite 300 h Washington, DC 20006 l EQE Project Number; 82001.11

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595 Market Street.18th Aoor 33CO IMne Avenue Ste M5 Two Annocel Lone. Ste.101 ton Poncnco. CA 9.1105 Newport Boocn. CA 92620 Son Dornon, CA 945&3 fe,ex U6166/(415) 195-f,500 (714) 852 9299 (415) 866 1766 ,

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23. INSTRUMENT RACKS Page 2 of 5 A

SUMMARY

OF SEISMIC ADEQUACY <

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' Instrument racks are structural steel-brace frames used to provide mounting for local controls and instrumentation, such as instrumentation signal transmitters to remote control panels. The equipment class of -

instrument racks includes both the rack structure and all instruments commonly mounted to a rack (e.g., transmitters, gauges, recorders, pressure switches, tubing, conduit, and junction boxes).

l DESCRIPTION OF EQUIPMENT WITHIN THE DATA BASE Instrument racks are a primary element in control and instrumentation systems. The starting point in instrumentation systems is a signal transducer, typically mounted to a pipe, pressure vessel, or an item of equipment to be monitored. In control systems, the starting point is a l control valve on a pipe. Most modern power and industrial facilities locate instrument racks in the general area of the equipment being controlled or monitored. A rack will typically consolidate the  !

transducer or control signals from several dquipment items in its j immediate vicinity. The components on an instrument rack either allow local monitoring or control of equipment in the vicinity, or amplify and

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transmit transducer signals to a remote readout or controller, typically i in the plant main control room.  !

Presented below are brief descriptions of the more common structural 1

configurations of instrument racks, and of the more common components '

) attached to racks. #

Racks Instrument racks usually consist of steel members (typically steel f angle, pipe, channel, or Unistrut) bolted or welded together into a frame. Components are attached either directly to the rack members or l to metal panels that are either welded or bolted to the rack. The racks are normally bolted to the floor at no less than four points: at the 713/ twt 01c23/1 23-1 g]

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< bottom corners of the frame and at the base of diagonal braces runn from the rear face of the rack to the floor. Floor-mounted instrument .

-racks range from 4 to 8 feet in height, with widths varying from 3 to 10 feet depending on the number of components supported on the rack.

Examples of this rack configuration are illustrated in Figures 23-9 and 23-13. ,

1 A simpler configuration of instrument rack is a sir 71e floor mounted post supporting one or two co conents as illustrate in Figure 23 11 -

Wall-mounted and structural column-mounted racks are occasionally used for supporting only a few compor.ents.

23-5. Examples are shown in Figure i' Rack-mounted components are usually relatively small with weight-of less than 50 pounds.

Components such as transmitters are sometimes mounted directly to walls or steel columns rather than supported on a rack.

Examples of direct wall or column mounting are illustrated in Figure 23-12.

Comoonents .

i Prior to the 1970s, instrumentation and control systems usually involved a combination of pneumatic and electronic systems. i!

Electronic systems I were used for functions such as temperature monitoring (through  !

thermocouple), starting, stopping, and throttling electric motors, and I

monitoring electric power (such as through ammeters). Pneumatic systems were used for monitoring fluid pressure, liquid level, fluid flow, and for adjusting pneumatically-actuated control valves.

In the 1970s electronic control and instrumentation systems replaced

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pneumatic systems in many power plant applications. The primary effect of this trend on instrument racks was the replacement of transmitters l that amplify a pneumatic signal (pneumatic relays) with transmitters that convert a pneumatic signal from the transducer to an electric signal to be transmitted to the main con!rol panel.

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j Depending on age of the particular facility, the data base offers a wide diversity of representation in both electronic and pneumatic  ;

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Attachent 1 Page 4 ot 5 instrumentation and control systems. Facilities constructed prior to 1970 usually include a mixture of electronic and pneumatic components on -

instrument. racks (Figure 23-7). Facilities constructed after 1970 show an. increasing trend toward electronic control and monitoring systems (Figure 23-8).

Typical components supported on instrument racks include: '

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a 1 Pressure Switches - piston, bourdon tube and diaphragm types (Figure 23-1).

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Transmitters - pneumatic or electronic pressure, level, I l

flow and temperature signal transmitters (Figure 23-2)

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Gauces - pneumatic, bourdon tube and diaphragm types (Figure 23-3), or electronic gauges or' meters J l

m Recorders - typically polar type chart recorders-1, a

Controlq - switches (including Mercoid-type switches),  ;

push buttons ., , I m I Valve coerators (addressed in Chapters 20 and 21) I J a Solenoids (addressed in Chapter 21) a Relays I e Associated conduit and tubina i ll Attachments to instrument racks include steel or plastic tubing from -

j pneumatic transducers (mounted in tanks and pipes) and conduit for transmitting tic converted signals to electronic instrument readouts mounted on central control panels. Junction boxes for instrumentation ,

cable are also frequently attached to instrument racks.

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( , The IBM / Santa Teresa Comouter Facility experienced a PGA of 0.379 with i strong motion occurring for about 8 seconds, during the 1984 Morgan Hill  !

Earthquake. This facility included several strong motion monitors, one ~

located in the free field,100 yards from the main building.

1 The facility includes several wall-mounted pressure transducers (Figure 23-12). fleither the transmitters nor their supports were damaged in the j earthquake. )

l IllSTANCES OF SEISMIC EFFECTS Atl0 DAMAGE The experience data base contains one instance of seismic effects to i instruments. There are no cases of seismic damage to instruments, the racks themselves, or to attached tubing or wiring.

At Steam Plant Number 3 on Adak Naval Station, affected by the 1986 Adak Earthquake, two pressure switches were tripped (Figure 23-14). During the earthquake, vibration of the internal push rod caused the actuation of diaphragm-type sudden pressure switches on two of the boilers. These sudden pressure switches are on a " hair-trigger" and are easily actuated by vibrations. The actuation of the pressure switches tripped an auxiliary relay, which in turn tripped the MCC controlling the boiler j fan motor. There was no damage to any of the equipment in this system.

No instances of seismically-induced damage to instruments, racks, or attached tubing and wiring were found in an extensive literature search and telephone survey.

RECOMMENDED RESTRICTIONS ON EQUIPMENT

l. The anchorage of instrument racks should be evaluated for their seismic adequacy.

2. The rack structure should be evaluated to ensure seismic adequacy.

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. 3. Sufficient slack should be provided between rack-mounted instruments and attached conduit and tubing to allow for seismically-induced j differential displacement.

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22. ENGINE-GENERATORS

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SUMMARY

OF SEISMIC ADEQUACY This class of equipment includes a wide range of sizes and types of

[ generators driven by piston engines or gas turbines. The equipment class of engine-generators includes all direct attachments to the skid -

j or engine block, but excludes freestanding peripheral equipment, such as control panels, that are not attached to the engine-generator structure.

DESCRIPTION OF EQUIPMENT WITHIN THE DATA BASE I l

l Engine-generators are emergency power sources designed to start l

automatically in the event of loss of offsite power. The primary l

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l components of engine-generators are discussed in the sections that '

follow.

Generators are typically the brushless rotating-field type with either a rotating rectifibr exciter, or a so!4d-state exciter and voltage regulator. Both synchronous and induction types of generators are used in power plant applications. Generator capacity is measured in kilovol t-amperes "(kVA) . In typical power plant applications, emergency I generators range from 200 kVA to 5000 kVA; electrical output is normally i at 480 volts or 4160 volts. i Recinrocatina-oiston enaines are the most common driver for emergency  !

power generators.

Piston engines are normally diesel-fueled, although engines that operate on alternate fuels such as natural gas or oil are -

common in facilities which process these fuels. In typical power plant -

applications, piston engines range from tractor-size to locomotive-size, with corresponding horsepower ratings ranging from 400 to 4000 hp.

Gas turbines are sometimes used as drivers for emergency generators due to the advantages of relative simplicity (compared to piston engines), l reliability, smooth operation, compactness, and freedom from peripheral cooling water systems. Turbines are typically fueled by diesel oil, i

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s 400 to 4000 hp. 1.ike piston-engines, turbines range in

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1 4- -Engine-generators normally include the p direct shaft connection, bolted to a common steel skid.

engine block also support peripheral cattachments The skid or thc su h piping, and a local control and instrumentation as conduit, panel, Figure 22-1 {

depicts a typical large diesel engine with its f peripheral attachments.

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The engine-generator systen includes peripheral heating, starting' and monitoring, as well as components for cooling,-

lubrication, and exhaust. supplying fuel, l

following components mounted: to the engine blo )

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Euel sucolv system - The fuel supplyessystem the incl i strainers, filters, piping and fuel pump.

m Lubrication system - The diesel-generator on lubri system includes piping, filters, end the oil pump .

u toolino system - This-system . includes a waj (radiator and fan) or a water-to-water hea t

c anger mounted to the engine block o~r ' supporting skid.

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e Heater - The electric jacket-water heaters are e to maintain the water temperature at 90*F r to in orde i

!! facilitate easier starting at cold ambient tem t; e peratures.

4 air intake system - This system includes the d '

fans and filters necessary to limit temperatur e (

.7 variations in the generator room and to, cool make clean

- air available to the engine. i a \

Exhaust system - The exhaust system includes aI

.h er, i and the ducting that directs the exhaust diesel room. e-out of th  !

There is generally a collar in the wall l opening and an expansion joint in the absorb ducting to operating vibrations and thermal expansion .

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Attachment 2 t Page 3 of 4 f a Startino system - Medium and large engines generally rely 4 .

,on compressed air for starting. Air in a receiver tank -

' powers air motors driving the crankshaft through a gear 1

linkage, or the air can go directly to the cylinders in i

L large diesels. Battery-driven electric motors are i

l .. sometimes used on smaller capacity systems.

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[ s local control and instrument canel - The local engine

{ control panel contains gauges and controls oesigned to monitor conditions such as low oil pressure, engine overheat, engine overspeed and generator overload.

Freestanding peripheral equipment that supports the operation of the engine-generator would typically include a local fuel (day) tank with its supply pump., an air compressor and plenum tanks for the engine k i l .- pneumatic starting system, switchgear cabinets (which can include an automatic transfer switch) and a control panel for the generator. This  !

equipment is ad' dressed separately in their respective equipment classes,

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.rather than as part of the engine-generator. Figure 22-2 illustrates an 1 engine-generator with typical attachments and peripheral equipment.

] Eauioment Anchorace

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All components of engine-generators are bolted either to the engine block or to the supporting skid. The skid is normally anchored to the supporting concrete foundation with cast-in-place bolts through bolt f) holes in the skid base channel. Smaller engine-generator units may be supported on isolation mounts. Manufacturers will sometimes supply

!} engine-generator sets and all peripheral equipment as a package mounted

, i in an outdoor enclosure. A variation of this design is to mount the engine-generator set on a trailer, as a mobile emergency power source.

Resistance to Seismic loads Diesel generator sets produce vibrations due to combustive forces, (

} ' torque reactions, structural mass and stiffness combinations, and 1

manufacturing tolerances on rotating components. These unbalanced l' v 4

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.i Page 4 of 4 Seismic damage to engine-generator sets from inadequat o anchorage, poorly designed isolation mounts, damage to attached pi i the instance at Elmendorf Hospital, discussed p ng (similar above) to ,

, or loss of water due to broken water mains (similar to the instance Municipal Light and Power Plant, discussed e Anchorage above) ha

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s occurred at several sites, including those affected by the arthquake, 1964 tiiigata E the 1969 Santa Rosa Ea-thquake, the 1971 San Ferna d n o Earthquake (including Olive View Medical Center, Pacoima Hospital , and Holy Cross Hospital), the.1972 Managua-Earthquake (including EllALUF ower Plant),

the 1978 Miyagi-ken-Okt Earthquake (including Sendai S ewage Treatment Plant and other pumping plants), and the 1986 tiorth P l a m. Springs i

Earthquake (including Whitewater Microwave Tower Commu i n cation Sjstem).

RECOMMENDED RESTRICTI0tlS ON EQUIPMEtlT 1.

The anchorage of engine-generators should seismic adequacy.

be evaluated f or sn. -: -

2.

3.

Isolation mounts should be evaluated c adequacy.for their seis The engine and generator should be mounted to a co prevent differential displacement. mmon base to not mounted to a common base, the pctential differentia i displacement should be evaluated.

4.

Sufficient slack should be provided in attached u cond it and tubing to allow for seismically-induced differentialcement. displa BIBLIOGRAPHY

l. ,

U. S. Nuclear Regulatory Commission. ,

December 1979.

Design, and Qualification of Diesel-generator sed as Units U " Selectio Standby (onsite) Electric Power Systems at Nuclea Regulatory Guide 1.9. r Power Plants."

Revision 2.

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