U-600964, Special Rept:On 870610,earthquake Estimated to Be 5.0 on Richter Scale Noted.Walkdowns of Plant Structures & Sys Conducted.No Damage or Abnormal Conditions Observed.Related Info,Including Sargent & Lundy ...Seismic...Rept, Encl

Special Rept:On 870610,earthquake Estimated to Be 5.0 on Richter Scale Noted.Walkdowns of Plant Structures & Sys Conducted.No Damage or Abnormal Conditions Observed.Related Info,Including Sargent & Lundy ...Seismic...Rept, Encl

ML20238B076
Person / Time
Site:	Clinton
Issue date:	06/19/1987
From:	Spangenberg F ILLINOIS POWER CO.
To:	Davis A NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML20238B078	List: ML20238B085 U-600964, Special Rept:On 870610,earthquake Estimated to Be 5.0 on Richter Scale Noted.Walkdowns of Plant Structures & Sys Conducted.No Damage or Abnormal Conditions Observed.Related Info,Including Sargent & Lundy ...Seismic...Rept, Encl
References
U-600964, NUDOCS 8709010053
Download: ML20238B076 (14)

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llLINO/S POWER COMPANY CLINTON POWER STATION, P.o. BCx 678, CLINTON. ILLINOls 61727 10CFR50.36 June 19, 1987 Docket No. 50-461 Mr. A. B. Davis Regional Administrator, Region III U.S. Nuclear Regulatory Commission 799 Roosevelt Road Glen Ellyn, Illinois 60137

Subject:

Special Report: Seismic Event at Clinton Power Station (CPS)

Dear Mr. Davis:

An earthquake was noticed by employees at CPS at approximately 6:50 p.m. on June 10, 1987. The epicenter was located near Lawrenceville, Illinois, approximately 120 miles southeast of CPS. The magnitude of the earthquake was estimated to be 5.0 on the Richter scale, according to the National Earthquake Information Center. The chronology of the actions taken by Illinois Power (IP) to evaluate this event is in.

CPS Technical Specification 4.3.7.2.2 requires any seismic event of greater than 0.02g vibratory motion to be reported to the Commission pursuant to CPS Technical Specification 6.9.2, SPECIAL REPORTS. During the event, the Main Control Room seismic monitor was out-of-service.

Engineering Evaluation of this event shows vibratory motion of approximately 0.02g.

Section 3.7.4 of the Clinten FSAR outlines the seismic instrumentation at the Clinton power plant. The time history system (FSAR Section 3.7.4.2.1) and related response spectrum analysis instrument were not operating at the time of the earthquake event. The inoperable status of this instrumentation was reported to the NRC per Illinois Power letter No. U-600941, dated May 21, 1987. The inoperable status of the instrumentation was the result of a lightning strike affecting the free field instrumentation a few weeko prior to the earthquake. Thus, no earthquake data was recorded by any of the active seismic instrumentation located at the plant during this period.

The passive instrumentation consisting of the Triaxial Response Spectrum Recorder at elevation 699' in the Circulating Water Screen House and the three Triaxial Peak Accelerographs located within the main plant did record the event. The data from the passive instrumentation vas analyzed by CPS Nuclear Station Engineering Department (NSED) with help from the Sargent and Lundy (S&L) Structural Design Department. A copy of the results of this analysis is attached (Attachment 2).

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Illinois Power conducted walkdowns of plant structures and systems.

These walkdowns revealed no damage or abnormal conditions as a result of the seismic activity of June 10, 1987. Walkdown methods, criteria and findings are discussed in Attachment 2.

The seismic activity at CPS was evaluated by Illinois Power and S&L to be well below the design basis for CPS. The 1 w energy level of this seismic event is evidenced by the lack of any damage to the systems and structures at CPS. Qualitative engineering evaluation estimates the gross ground acceleration at 0.02g.

Illinois Power has contacted the supplier of the Triaxial Response Spectrum Analyzer (Engdahl Enterprises) to review the recorded data and provide technical input. Engdahl Enterprises' input will be utilized to confirm our findings. However, at this time Engdahl Enterprises has not completed its evaluation.

Should Engdahl Enterprises' evaluation provide additional information pertinent to IP's conclusions, a supplemental report will be provided.

If there are any further questions on this topic, please contact me.

Sincerely yours R$'.lIf O

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A. Spang berg, II Manager - Licensin and Safety GSL/ckc Attachments cc: B2iL.~Siegel, NRC Clint"on Licensing Project Manager NRC Resident Office Illinois Department of Nuclear Safety Document Control Desk

i SEISMIC EVENT CHRONOLOGY June 10, 1987 1850 Plant Personnel experienced a minor seismic event. The Shif t Supervisor felt a minor " bump".

Plant operators begun to carry out the steps cf CPS 4301.01, EARTHQUAKE.

1852 -

Standby EHC Pump Auto-Started - an operator was sent to investigate.

Staff Assistant Shift Supervisor received an initial 1854 report from St. Louis University that confirmed that a small seismic event had taken place possibly in Southeastern Illinois.

1900-2000 -

The Shift Supervisor called the Plant Manager to inform him of the event and actions taken in response.

The Plant Manager directed plant personnel to begin evaluation of the seismic scratch plates.

1916 E-Area operator reported everything is normal at the dam area.

Larry Haug (Plant Staff - Technical) was called in to collect data from seismic scratch plates.

1940 D-Area operator reported no problem with EHC arca, 1942 -

Radwaste Operations Center (ROC) operator reported hearing a noise he associated with a hairline crack in the ROC west wall.

NRC (Bethesda) notified of seismic evenr..

1945 Note: An Unusual Event was not declared at this time since the Control Room Seismic Monitor was out-of-service and other means available to directly determine the magnitude of the event had not yet been interpreted. Also plant personnel believed the magnitude of the event to be minor in nature (based on the minor " bump" that they felt).

Therefore, the Plant Management did not believe this event met the j

bases for declaring an Unusual Event.

l Plant Manager arrived on site.

2000-2100 Plant Manager requested a printout of all security alarms just befcre, during, and just af ter the seismic event.

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Plant Manager requested additional inspections by j

Engineering and Quality Assurance.

Plant Staff requested that NSED help cvaluate the data from the seismic scratch pads located in the Screenhouse.

Results of preliminary operator walkdowns show no signs of damage from the seismic event, t

NSED and QA call in personnel to perform detailed 2100-2300 walkdowns/ inspections.

Engineering and QA teams developed criteria, parameters 2300-2400 methods to use, and what specific areas should be inspected.

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June 11, 1987 1

I Engineering and QA inspection teams dispatched, j

0000-0100 i

NSED began evaluation of seismic scratch plate data.

Seismic scratch plate instruments were calibrated to 0100-0200 verify accuracy.

1 P. Hiland (NRC Resident Inspector) arrived on site.

l NSED requested assistance from S&L to help evaluate 0200-0300 seismic scratch plate data.

1 Engineering and QA inspection teams returned from 0300-0400 inspection, were debriefed. No obvious evidence of l

earthquake damage was reported. A hairline crack in the j

face of the west wall of the ROC was inspected. Evidence l

indicated that the crack was old (i.e., existed before l

this event). Therefore it was dispositioned as being not related to the seismic event.

l Data from seismic scratch plates indicated that the 1

0342 Technical Specification value of 0.02g acceleration may l

have been exceeded at some frequencies which requires I

calibration of equipment involved within 5 days, analysis of data, and submission of a special report to the NRC within 10 days.

Notification of Unusual Event declared because it is 0345 required by the EPIP for a seismic event in excess of 0.02g acceleration.

0353 -

State of Illinois notified of Unusual Event.

Notification of Unusual Event cancelled.

0355 State of Illinois notified of cancellation of Unusual 0358 l

Event.

P. Hiland debriefed ou event.

0400-0500 0435 Notified NRC that an Unusunl Event had been declared at 0345, and cancelled at 0355.

Data from screenhouse seismic scratch plate indicates that 0560-0600 accelerations at two high frequencies may have exceeded the values for an Operational Bases Earthquake (OBE).

I Preliminary discussions with seismic specialists from S&L confirmed that an OBE had not occurred.

Personnel take pictures of various site offices wh1ch 0700-0800 indicated no effects of seismic event.

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Structural Engineer dispatched to perform inspection of 0900-1000 dam toe area - no apparent damage.

S&L seismic specialist indicated that the higher accelerations at high frequencies are typical of midwestern earthquakes, and that the seismic event at CPS did not exceed the OBE.

S&L began preparing detailed analysis of this event. NSED will review this report, and prepare an additional report.

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!,1987 JUN 18 $87 un F. A. SPANGEftBER F. A. Spangenberg, V-920 Seismic Disturbance at Clinton Power Station This memorandum provides a technical discussion of the impact of the seismic event which occurred June 10, 1987 at Clinton Power Station.

The earthquake was noticed by employees at CPS at approximately 6:50 p.m.

The epicenter was located near l

Lawrenceville, Illinois, approximately 120 miles south-east of CPS.

The magnitude of the earthquake was estimated to be 5.0 on the Richter scale, according to the National Earthquake i

l Information Center.

Subsequent to the event, a Plant Walkdown group was organized, consisting of approximately 15 people from NSED, IPQA, i

and Sargent & Lundy, Structural Engineering Division.

The group members were briefed at midnight and inspections were performed Members were briefed i

by 7 teams between 12:30 a.m. and 3:00 a.m.

on specific areas and components considered vulnerable to seismic i

activity.

There were no items found to be affected by the seismic event.

At one specific location an operator reported

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that he heard a noise during the event and later. observed a small l

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crack in a wall.

Structural engineers from the Walkdown Group

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J inspected the area and determined that the hairline crack was due to normal concrete shrinkage and was not associated with the seismic event.

Main dam inspections were performed during the night by NSED Civil / Structural and QA personnel, and again the following morning by NSED Civil / Structural and NP&S personnel.

These inspections revealed no apparent damage due to the earthquake.

At the time of the event, all ' active' seismic instruments, which provide data directly to the main control room, were not operable.

These instruments include a response spectrum analyzer, one triaxial accelerometer outside the plant, three

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triaxial accelerometers inside the power block, and a triaxial seismic trigger on the base mat.

The triaxia?. accelerometers feed data directly to a response spectrum anttrzer (RSA) in the main control room.

The RSA is capable of computing and plotting the response spectra from a seismic event from the data provided by the triaxial accelerometers.

The computed values are compared 3

automatically by the RSA against the analytical response spectra i

for the sensor location which is permanently stored in memory-If any axis of the sensors exceeds these stored values, an indicating light and an annunciator in the main control room are

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actuated.

One annunciator will inform the operator'if any OBE value is exceeded, and another annunciator if any SSE value is exceeded.

The RSA provides detailed information as to the frequencies, axis, and sensor which resulted in actuation of the annunciator.

' Passive' seismic instruments were operable at the time, including one response spectrum recorder in the screen I

I house and three triaxial peak accelerographs in the power block.

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Data was recorded by the passive instrumentation in the plant.-

l The data recorded by'the response spectrum recorder at el. 699 in the screenhouse is scribed on thirty-six plates by reeds which are tuned to specific frequencies.

This data was measured and 4

calculated by Plant Staff Technical personnel per CPS 1337.05 and the results were provided to NSED for analysis.

This data was.

plotted to form response spectra curves and compared to the design basis response spectra curves at el. 699, screenhouse.

This data revealed that, generally, very low energy levels of

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seismic activity occurred.

Thirty-six data points (twelve I

frequencies in each of three orthoganal directions) were recorded.

Two instances of Operational Basis Earthquake (OBE) exceedance at high frequency points were observed.

The S&L Structural Department has discounted the effect of these data l

points as negligible for the event since the overall seismic energy level was substantially lower than the OBE.

Engineering estimates of the gross ground acceleration are approximately 0.02g the OBE gross ground acceleration is approximately 0.10g.

1 The engineering estimate of 0.02g is a qualitative assessment of ground acceleration as it relates to descriptive passages in the Modified Mercalli Intensity Scale as shown in Table 2.5-61 of the CPS FSAR (Attachment A) and compared with Table I of Attachment "B".

Attachment B is specifically mentioned as an acceptable j

reference document in section 2.5.2 of NUREG-0800.

Attachment C 1

is a memorandum to File documenting that unsupported items l

outside the Protected Area were not dislodged from their normal positions.

Due to the fact that no significant operational impacts occurred and plant inspections revealed no apparent structural damage, NSED has concluded that the seismic event imposed earthquake loadings on the plant structures which were within the limits of l

the operational basis earthquake.

S&L has concurred in this conclusion in their letter SLS-I-5848, dated June 16, 1987 (Attachment D).

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E. W.t Kant Director l

Design Engineering Attachments ME/ amp M997/M51 cc:

D. P. Hall, V-275 J. S. Perry, V-275 J. W. Wilson, T-31 E. W. Kant, V-928 R. T. Kerestes, V-928 F. G. Schwarz, V-928 J. H. Mansker, V-928 M. E. Ehalt, V-928 i

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ATTACHMENT A i

CPS-FSAR TABLE 2.5-61 l

i MODIFIED HERCALLI INTENSITY (DAMACE) SCAI.E OF 1931 l

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Not felt except by a very few under especially favorable circum-stances.

(I, Rossi-Forel Scale) l II.

Felt only by a few persons.at rest, especially on upper floors of l

buildings. Delicately suspended objects may swing.

(I to II, Rossi-Forel Scale)

III.

Felt quite noticeably indoors', especially on upper floors of.

buildings, but many people do not recognize it as an' earthquake, d

Standing motorcars may rock slightly. Vibration like passing of

'I truck. Duration estimated.

(III, Rossi-Forel Sca.le)'

IV.

During the day, felt indoors by many, outdoors by few. At night,'

some awakened. Dishes, windows,. doors disturbed; walls make creaking sound. Sensation like heavy truck striking building.

Standing motorcars rock noticeabl,y.

(IV to V, Rossi-Forel Scale)

V.

Felt by nearly everyone, many awakened.

Some dishes, windows, etc., brolen; a few instances of cracked plaster; unstable objects overturned. Disturbances of trees, poles, and other tall objects sometimes noticed. Pendulum clocks may stop.

(V to VI, Rossi-Forel Scale) l

' VI.

Felt by all, many frightened and run outdoors.

Some heavy furni-ture moved; a few instances of fallen plaster or damaged chimneys.

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Damage slight.

(VI to VI g Rossi-Forel Scale)

VII.

Everybody runs outdoors. Damage negligible in buildings of g'ood design and construction; slight to moderate in vell-built ordinary structures; considerable in poorly built or badly designed struc-tures: some chimneys broken. Noticed by persons driving motor-5 cars.

(VIII, Rossi-Forel Scale)

VIII. Damage slight in specially designed structures; considerable in ordinary substantial buildings,.'with partial collapse; great in pocely built structures. Panel valls thrown out of frame struc-tures. Fall of chimneys, factory stacks, columns, monuments, walls. Heavy furniture overturned. Sand and mud ejected in small amoonts. Changes in well water. Persons driving motorcars dis-turbed.

(VIII+ to IX, Rossi-Forel Scale)

IX,,

Damage considerable in specially designed structures: well de-signed frame structures thrown out of plumb; great in substantial buildings;.with partial collapse.

Buildings shifted off founda-.

tions. Ground cracked conspicuously. Underground pipes broken.

1 (IX+, Rossi Fcral Scale) j X.

Some vell-built s.t oden structurc.s destroyed: most masonry and frama structures cestrcyed with foundations; ground badly cracked.

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Rails bent. Landslides considerable from river banks an'd steep slopes. Shifted sand and mud. Water splashed (slopped) over banks.

(X, Rossi-Forel Scale)

XI.

Few, if any, (masonry) structures remain standing.

Bridge.s de-

- 1 stroyed. Broad fissures in. ground. Underground pipelines com-pletely out of service. Earth slumps and land slips in sof t l

ground. Rails bent greatly.

XII..

Damage total.. Waves seen on' ground surface. Lines of sight and l

level distorted. Objects thrown upward into the air.

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1 For the MKS intensity sede (Medvedev and Sponheuer,1969) and for the Japanese JhtA scale (Okamoto.1973), the range of possible pcek accelerations' is presented in Figurs 3 and Table 1.

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"On the derrelation o'f Seismic Intensity' Scales' 'with f:be !

Peaks of Recorded Strong Ground Motion by M. D. Trifunac and A. G. Bradyr Bulletin of,th'e, a

seismological Society of America vol.'6.5, No.

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ATTACliMENT C June 11, 1987 T0:

FILE FROM:

utherford, V-905

SUBJECT:

Tour of office trailers subsequent to the earthquake which occurred near.the Clinton Power Station on June 10, 1987 A walking tour of several office trailers at the Clinton Power Station was conducted on June 11, 1987 between 7:00 AM and 7:45 AM. The attached pictures were taken of items which may have fallen or become disoriented as a result of the earthquake which occurred on the evening of June 10, 1987.

There were 40 items noted which appeared to be out of their normal locations. The locations of the pictures taken are delineated on the attached page.

OLR/lej Attachment cc:

W. Connell, V-928 (w/o pictures)

J.A.Fertic,V-923(w/opictures)

E.Corrigan,V-905(w/opictures) l l

E__._________._________._____.______

________________E.__

Locations of Pictures Taken on June 11, 1987 1

1.

QC trailer (C1) outside of supervisor's office (2 pictures) l l

2.

QTS trailer (C1) - office area j

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Pinkerton trailer - storage area j

4.

GE trailer and temporary structure - file area

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GE trailer and temporary structure - office. area 6.

NSED Configuration Management trailer (B1) - office area 7.

NSED trailer complex - file area l

8.

NSED trailer complex - reference material storage f

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NPS Reference Library - vendor storage l

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ATTACHMENT D I

SARGENT& LUNDY ENGINEERS j

rouNocosees SS C A S T M O N 8t O E STRECT CHICAGO, ILLINOIS 60603

( 388 ) 899-2030 TWM 910 2313807 SLS-I-5848 June 16, 1987 Project No. 7685 File No. 1.1, 5.90.3 i

Illinois Power Company Clinton Power Station - Unit 1

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l Seismic Event Report Mr. W. Connell, Manager Nuclear Station Engineering 1

Illinois Power Company I

Clinton Power Station P. O. Box 678 - Mail Code V-928 Clinton, IL 61727 1

Dear Mr. Connell:

Sargent & Lundy has completed an engineering review of the seismic data recorded at the Clinton Site resulting from the southeastern Illinois earthquake on June 10, 1987.

The re-corded data was received on June 11, 1987 and was transmitted formally per FPR 201,600 on June 12, 1987.

The results of our review are enclosed in a report prepared by Mr. A. K. Singh, Structural Department Design Director.

The report is titled " June 10, 1987 Seismic Event Report" and dated June 12, 1987.

Yours very trul,

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O Steve R. Raupp SRR/as Senior Structural Engineer Enclosures Copies:

D. P. Hall (1/1)

A. K. Singh (1/1)

E. W. Kant (1/1)

D. K. Schopfer (1/1)

CPS D/R Center (1/1)

R. A. Witt (1/1)

B. A. Erler (1/1)

J. W. Blattner (1/1)

J. M. McLaughlin (1/1)

D. J. Gullaksen >ll/1)

H. M. Sroka (1/1)

W. P. Mcdonald (1/1)

P. L. Wattelet (1/1)

J. S. Steele (1/1)

C____.____________

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