ML20085C974

AO 50-254/74-29:on 741010,loud Noise,Alarms & Chimney Radiation Monitors Showing Increase Indicated Occurrence of Offgas Detonation.Caused by Const Personnel Grinding Through Unpurged Section of Piping.Filters & Discs Replaced

ML20085C974
Person / Time
Site:	Quad Cities
Issue date:	10/18/1974
From:	Kalivianakis N COMMONWEALTH EDISON CO.
To:	Oleary J US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML20085C969	List: ML20085C967 ML20085C972 ML20085C974
References
AO-50-254-74-29, NJK-74-339, NUDOCS 8307130299
Download: ML20085C974 (12)

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C C-uad-Cibc4Generat:ng Station Post Office Box 216 Cordova Illinois 61242 (fi;*-[pC)

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October 18, 1974 - \ c;

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q Ns Mr. John F. O' Leary, Director Directorate of Licensing Regulation U. S. Atomic Energy Commission Washington, D. C. 20545

Reference:

Quad-Cities Nuclear Power Station Docket No. 50-254, DPR-29 Appendix A, Sections 1.0.A.3, 1.0.A.5, and 6.6.B.l.a

Dear Mr. O' Leary:

Enclosed please find Abnormal Occurrence Report No. AO 50-254/74-29 for Quad-Cities Nuclear Power Station. This occurrence was previously reported to Region III, Directorate of Regulatory Operations by telephone on October 10, 1974, and to you and Region III, Directorate of Regulatory Operations by telecopy on October 10, 1974.

This report is submitted to you in accordance with the require-ments of Technical Specification 6.6.B.1.a.

Very truly yours, COMMONWEALTH EDISON COMPANY QUAD-CITIES NUCLEAR P WER STATION

/r-Abik N. J. Kalivianakis Station Superintendent NJK/CWS/zr cc: Region III, Directorate of Regulatory Operations J. S. Abel ~

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O REPORT NUMBER: AO 50-254/74-29 REPORT DATE: October 18, 1974 OCCt1RRENCE DATE: October 10, 1974 FACILITY: Quad-Cities Nuclear Power Station Cordova, Illinois 61242 Identification of Occurrence:

Off Gas Detonation, Unit 1 Conditions Prior to Occurrence:

Unit 1 at 520 MWe increasing at 3 MWe/hr.

Unit 2 at 620 MWe increasing at 3 MWe/hr.

Unit 1 off Gas 3165 uci/sec. at the Main Chimney with ,

493 MWe at 0114 a.m.

Unit 2 Off Gas 28,832 uCi/sec at the Main Chimney with 639 MWe at 1:19 a.m.

Construction Activities in progress in the Off Gas Filter Building 1B SJAE in service 1B Off Gas Filter in Service Description of Occurrence:

At 10:04 a.m. on October 10, 1974, several personnel who were in the vicinity of the main chimney, in the off gas filter i - building,.and in the west side of the Turbine Building heard a loud " Boom". Control' Room Alarms were received for SJAE OFF

. GAS IIIGH FLOW, OFF GAS FILTER HIGH DP, SJAE lA LIQUID DRAIN HIGH LEVEL, SJAE 1B LIQUID DRAIN HIGH LEVEL, and SJAE lA LIQUID DRAIN LOW LEVEL. Shortly thereafter, the main chimney radiation monitors showed a step increase from approximately 30,000~uci/sec to approximately 100,000 uCi/sec. These indications led to .

the conclusion that an off gas detonation had occurred. The station procedure for off gas detonations was then followed.

At 10:07 a.m., a condition ABLE was declared and load reduction was initiated on Unit 1 to help maintain condenservacuum with erratic air ejector operation.- Unit 1 load was 399 MWe at 10:10 a.m. Personnel in the vicinity of the chimney checked the 4 off gas filter building and evacuated the personnel in that building. About three minutes later, an area-radiation monitor in_the off gas filter building alarmed. At 10:12 a.m., the station siren was sounded to effect an evacuation of the Turbina Building. The Station Environs Team was activated to investigate off site radiological consequences of the in'cident.

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O The 1A steam jet air ejector was placed in service and the 1B steam jet air ejector was removed from service and isolated by 10:30 a.m. Within approximately ten minutes, the main chimney radiation monitors decreased approaching pre-incident levels.

Also, the area radiation monitor alarms in the area of the SJAE rooms were cleared. The 1A off gas filter was placed in '

service and the la off gas filter was removed from service and isolated by 10:50 a.m. A check of the off gas filter building piping revealed a flow path of off gas to a pipe on which grinding was taking place at the time of the off gas detonation. The pipe, which had been ground through, was isolated at approximately 11:00 a.m. Condition ABLE was officially terminated at 11:04 a.m. A later inspection confirmed that the 1B SJAE rupture disc was ruptured, thus allowing off gas to enter the SJAE room, causing local area radiation monitors to alarm, and decreasing off gas hold up time to the chimney caus-ing an increase in off gas radiation at the main chinney monitors.

The 1A off gas filter was tested for efficiency and was de-termined to be defective at 2:00 p.m. An orderly shutdown was initiated, the turbine was tripped at 5:30 p.m., and the Unit was in shutdown mode at 9:15 p.m. on October 10, 1974.

DESIGNATION OF APPARENT CAUSE OF OCCURRENCE:

Installation / Construction The cause of this off gas detonation is attributed to construction personnel grinding through an unpurged and improperly isolated section of off gas piping in the new off gas filter building.

At the time of detonation, a modification was being made on the new piping. The personnel working on the job were under the impression that the subject piping had never been placed in service and thus could not contain off gas. Subsequent exami-nation showed that a flow path did e::ist from the off gas filter bypass line to the grinding location. This filter bypass line was in service.

Contributing factors include failure of construction personnel to notify operations personnel of work being done, failure to have the line taken out of service properly before beginning work, and failure to purge a'line possibly containing explosive l

. gases before beginning work.  !

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ANALYSIS OF OCCURRENCE:

The of f gas detonation resulted in:

1. Rupture of the 1B SJAE rupture disc.

2. Rupture of the 350 psi 2" rupture disc on the off gas discharge pipe upstream of the holdup line.

3. Demolition of the 1B Off Gas Filter.

4. Apparent Fire damage to the 1A off gas filter, probably due to small leakage of one of the filter isolation valves.

There were no personnel injuries and no excessive personnel radiation exposures related to this incident.

The wind was from the south during this incident at up to approximately 6 mph. On site environs station No. 1 is located due north of the station. The recording area radiation monitor at this location showed an increase during this incident as shown in attachment "A".

These results correspond to the indicated chimney radiation monitor increase from approximately 30,000 uCi/sec to 100,000 uCi/

sec as shown in attachment ' B".

This indicated increase is due to a combination of factors caused by the decrease in holdup time. The shorter holdup time caused an increase in the 22 fission product gases. The decrease in holdup also caused a change in composition which would' affect monitor calibration. Also, the shorter holdup allowed N13 to become a contributing factor.

Initial environs team samples showed minimal environmental implica tions . These were confirmed by an extensive environmental sampling program performed by Eberline Instrument Corporation on the afternoon of October 10, 1974. These results are enclosed as attachement "C".

CORRECTIVE ACTION Immediate corrective action was taken as described in " Description

, of Occurrence." Other follow-up action included replacing both off gas filters, and replacing both ructure discs. In addition, the instruments involved in monitoring the off gas holdup pipe were checked for damage and calibrated as required.

Immediately following the incident, a meeting was held between the Station Superintendent, the Commonwealth Edison Station l Construction Representative, and Contractor personnel involved.

It was again made clear that station procedures must be followed and that adherance to station procedures could have prevented this incident.

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FAILURE DATA  !

l Although this is the third off gas detonation to have occurred at Quad-Cities Station, the causes of previous detonations are attributed to ungrounded filters and possible unknown factors.

This occurrence was due to personnel error and not equipment failure or malfunction and the cause was readily explainable.

It should be noted that environmental implications on the health and safety of the public in this case were minimal, as expected

~ based on actual samples, calculations, and previous experiences.

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ENNRCiNE INSTRkiENT CORPORATION [h:  !

PLEACE REPLY TO: MIDWESTERN FACILITY 245 HOOSEVELT ROAD WEST CHICAGO, ILLINOIS 60185 PHONE (312) 2319400 E

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kl953-1973,/

15 October 1974 Quad Cities Nuclear Power Station P.O. Box 216 ,

Cordova, Illinois 61242 Attention: Mr. N. J. Kalevianakis

Dear Mr. Kalevinnakis:

The attached sheets list data obtained during the special environmental sample collection program of 10/10/74. We have also included your copy of the sample collection data sheet. These data confirm previous verbal reports of results, and are discussed below.

Gamma Isotopic Analyses - Soil Cs-137 was the only fission product gamma emitter detected. Concentra-tions for all stations sampled except Q-03 were within the range expected (0.1 - 0.4 pCi/ge) from worldwide fallout. Soil from Q-02 had a Cs-137:

concentration of 1.1 0.2 pCi/gm. While this value (which was confirmed by separate analyses of two aliquots of the sample) is somewhat higher than expected, in the absence of other (especially fresh) fissica pro-ducts, we feel this activity is unlikely to be due to station operations, but the possibility does exist.

Gamma Isotopic Analyses - Vegetation

> Cs-137 was detected in low concentration (0.3 0.2 pCi/go) at Q-15, but was not detected in vegetation samples collected ~elsewhere. As with the soil samples, this van the only fission product ga=ma emitter detected.

Here, too, plant operations are a possible, but not probable, source of this radioactivity.

Gamma Isotopic Analyses - Air Particulates, No fission product gamma emitters were detected in any air particulate filter at a system sensitivity of 0.01 pCi/m 3 (30). Naturally occurring

- Be-7 was detected in all samples of this type and naturally occurring K-40 in some.

Airborne I-131

'A composite of all charcoal cartridges co11ceted.(8) counted for 500 min-utes on the GeLi system. A small, but clearly detectable number of counts were observed in the 364 KcV cnergy peak, but could not be quantified N.

w^ P. O. BOX 2103 AlHPORT ROAD SAN TA FE, NEW MEXICO 87501 PHONE (505) 0821881 TWX 9'0-985 0678

t GA30fA ISOTOPIC ANALYSES OF SOIL, VEGETATION AND AIR PARTICULATE SAMPLES COLLECTED 10/10/74 ,

pCi/g* Soil pCi/g* Vegetation Air Particulates pCi/m 3, Station Cs-137 Others(1) Cs-137 Others(1) Fission Products Gamma Emitters Q-01 0.3 0.1 <.03 <0.37 <0.37 <0.01 Q-02 0.4 1 0.1 <.03 - -

<0.01 Q-03 Q-12 1.1 0.2 0.2 0.1

<.03

<.03

<0.21

<0.18

<0.21

<0.18

<0.01

<0.01 lll Q-13 <0.03 <.03 <0.30 <0.30 <0.01 Q-14 0.2 ! 0.1 <.03 <0.20 <0.20 <0.01 Q-15 0.3 ! 0.1 <.03 0.27 0.18 <0.20 <0.01 Q-16 0.1 2 0.1 <.03 <0.20 <0.20 <0.01

• All quoted uncertainties are 2a, "<" data are 3a.

(1) Spectra are computer scanned from ~1 to ~2000 kev, with special attention to fission product

, nuclides. Naturally occurring gamma emitters such as K-40, radium and its daughters, and Be-7 i f were present in most samples but are not included in "others" above.

l RADI0 IODINE (I-131) IN CHARC0AL CARTRIDGES COLLECTED 10/10/74 gg)

Station: 0-01 0-02 0-03 0-12 0-13 0-14 Q-15 0-16 I-131 pCi/m 3 <.04 <.04 <.04 <.04 <.04 <.04 <.04 <.04 ION CHAMBER READINGS

, 10/10/64 '

Station mR/ Week

• Station mR/ Week

• Q-01 FS 2.8 Q-13 5.6 (1) 2.1 Q-02 2.1 FS Q-14 2.8 2.8 Q-03 2.0 2.1 Q-15 2.5 1.4 Q-12 1.4 1.4 Q-16 2.8 2.8

• Readings were taken after 5 days' exposure and are presented normalized to 7 days' exposure.

(1) Apparently anomalous reading.

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. . .. o o Mr. N. J. Kalevianakis Page 2 15 October 1974 -

Airborne I-131 (Continued) because the system cannot be calibrated for this non-standard geometry.

Analyses of individual cartridges on a 4" x 4" NaI(Tl) crystal with a single-channel spectrometer set for I-131 ga=nas indicated that the I-131 concentration was <0.04 pC1/m3 (3a) corrected for decay to time of sampling at all stations. The apparent presence of I-131 in the com-posite is probably either an artifact or real, but detected only because the composite is eight times as large as an individual sample.

Ion Chamber Readings Adopting the usual convention of accepting the lower of the two ion chambers as the reporting value and normalizing to a seven-day exposure, Q-14, Q-16 and Q-01 indicate doses somewhat higher than usual. These increases may be due to station operations, but in view of the wide variability of ion chamber data is probably not statistically demon-strable.

Cross Beta in Air Particulates Gross beta concentrations in air particulate filter samples collected were, for all stations sampled, well within the values expected for these samples. The spread of concentrations observed was very small .

indicating similar concentrations in the whole area sampled. There is no indication that radicactivity attributable to station operations was present in any of these samples.

Summary of Stations Sampled Station Location Time of Sampling Q-01 Nitrin .

1655 Q-02 Clinton 1730 Q-03 Sikkema Farn 1635 Q-12 Hanson's Landing 1800 Q-13 Low Moor 1815 Q-14 On-Site, North 1540 Q-15 On-Site, East 1500 Q-16 On-Site, South 1530 Sincerely yours, EBERLINE INSTRUMENT CORPORATION

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t Trautman MT:md Manager, Midwest Facility cc: John Golden, CECO Rich Flessner, Quad Cities' [

. Attach.

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.. l GROSS BETA CONCENTRATIONS IN AIR PARTICULATE FILTERS Collected 10/10/74 Station m3 pCi/m 3( 2a)

Q-01 216 0.05 1 0.01 Q-02 210 0.05 0.01 Q-03 210 0.06 1 0.01 Q-12 210 0.06 0.01 Q-13 210 0.05 0.01 Q-14 210 0.06 0.01 L Q-15 210 0.06 ! 0.01 Q-16 210 0.06 0.01 W

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