ML12040A274

E-Mail from G. Wilson, NRR to D. Merzke, EDO; Subject: Seismic Instruments at North Anna

ML12040A274
Person / Time
Site:	North Anna
Issue date:	08/31/2011
From:	George Wilson Office of Nuclear Reactor Regulation
To:	Boger B, Mchale J, Daniel Merzke Office of Nuclear Reactor Regulation, NRC/EDO
References
FOIA/PA-2011-0357
Download: ML12040A274 (20)

Text

Martin, Robert From: Wilson, George Sent: Wednesday, AuuDst 31, 2011 2:32 PM To: Merzke, Daniel; McHale, John; Boger, Bruce; Leeds, Eric; Grobe, Jack; Hiland, Patrick; Giitter, Joseph; Skeen, David Cc: Khanna, Meena; Manoly, Kamal; Munson, Clifford; Karas, Rebecca; Kammerer, Annie; Martin, Robert; Kulesa, Gloria; Zimmerman, Jacob

Subject:

seismic instruments at North Anna Attachments: seismic NCRODP.ppt See attached George Wilson USNRC EICB Branch Chief, Division of Engineering Mail Stop 012H2 301-415-1711 32

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Tri-Axial Peak Accelerog ra ph.-

Tri-Axial Response Spectrum Recorder Seismic Tri ge r eis mic, Switch Tn~-Axial Time-Histor Accelerogra~ph

Ter'ms.

The Seism ic Monito ring, System has both active and passive com~ponents :: '** !*'* :

Active components Require an outside, resource.to thenir design function rperfr (electricity,' com pressed air, nitrogen, etc.)

The Tri-Axial Time-History Accelerograph is* the":only active device Passive components Require no outside resource to perorm design functions These include the Tri-Axial. Peak Acelerograph and the Tri-Axial Response Spectrum Recorder

Tri-Axial..

Pea k Ac ce lerog-ý raphh

EX 4 (2 pages)

Tri-Axial Peak Accelerograph A passive instrument that measures and records wide-band, low frequency, acceleration it measures a riey detectors in three directiolns:

- Vertical (up.down) gLongitudinal ,(North-So u.t.h)

,.Transverse (East-West)

The are, three. Tri-Axial Peak Acce erog raph's

Tri-Axial Peak Accelerog-raph The three detector locations are:.-.

- Unit-I containment basement,.on-."C" .Sl accumulator discharge pipe downstream. o.0fl-SI-MOV-i 8650

- Unit-I containment RHR.flat, on "B" RHR heat exchanger

-1".Auxiliary building third floor, on the unit-I "A" CC-heat exchanger,

Tni-Axial Response. spectrum Recorder

EX 4 (6 pages)

Tri-Axial Res po n se ,:$Spectrum Recorder A passive instrument that is similar to the peak accelerograph Has: 12 reeds of different lengths and weights monitoring each direction (36 total)

Measure and record acceleration over a range of 12,specific frequencies in the three monitored direction s,

-Vertical (u p- down)

Longitudinal (North-South)

- Transverse (East-West) ,, " * . 9,.;

.'t' , 9 The. are four Trii,-AXial'. R-e s, oi- ýe- S. R--ecor ers 9 9 94

Tri-Axial Response Spectrum Recorder Thelfour detector locations are:--:,'

- Auxiliary building m a t,- between Unit-1 and Unit-2 CCG pumps

- Auxiliary building 3rd. flooýr, on support near unit-1 "A" CC heat exchanger Unit-I conta nment basement, outside crane wall near PDTT Unit-1 containment, RHR pu m p and h eat exchanger area

Tri-Axial Response S pectrum Recorder unique is'its, abilit t-Yo mo~nitor peak acceleration in each of 12 different frequencies: (2 24. Hz all three directio'n in Protected from moisture by use of Adesic"cant The containment mat tri-axial response spectrum recorder, while considered a passive device has an mponent 36dual-actioncmicro-switChes which input, to the peak shock annunciatbr panel--

The1 first contact on eachjmicro."-s:wihi set, to pickupat approximately'67% of DBE (AMBER)

The second contact is Set at 100% :f DBE (RED)-,

These alarms do not directly.-feed the ....MCR annunciators

Seismic Trigger Tr-Axial Seismic Trigger The trigger is an "on-off", switch set at 0.01 g's in any direction The trigger has pendulums in the horizontal and vertical directions (imagine a grandfather clock)

Motion exceeding 0.01 g's in any direction, will cause the switch to pick-up The signal is sent to the seismic panel in the MCR The seismic trigger is loCated on the seismic instrument pad in the unit-I containmenit:: basement

Containment Structure Instrument Transmitter Rack 1-100 (Area Enlarged Below)

Seismic Instruments Pad Triaxial Time-History Accelerograph Seismic Trigger Triaxial Seismic Switch Triaxial Response Spectrum Recorder SEISMIC INSTRUMENTS LOCATION (CONTAINMENT 216' 11" ELEVATION)

Seis~mic Sich-Tri-Axial Seis mic Switch The seismic switch detects motion using.accelerometers-,

The seismic switch operation is similarto the analog time-7history.-

accelerographs-"

The voltage output is sent to internal relays which provide an "on-off" output when the setpoi nt-iseexcee ded Its output is used to directly actuate a.MCR annunciator

Tri-Axial Seis mic Switch The seismic switch has two setpoints (OBE)

- Vertical - 0.04 g's

- Horizontal - 0.06 g's.

The seismic switch performs the following:

-Alerts the operator- EARTHQUAKE- JIN .STRUMEN

• T PANEL TROUBLE.

Illuminates local yellow lIght for approximately 10 se condS,,s.-

then resets automatically:

The seismic switch is located next to the seismic trigger in the Unit-I containment basement.

EX 4 (5 pages)