ML20084L489
| ML20084L489 | |
| Person / Time | |
|---|---|
| Site: | Quad Cities  |
| Issue date: | 10/27/1970 |
| From: | Brian Lee COMMONWEALTH EDISON CO. |
| To: | Morris P US ATOMIC ENERGY COMMISSION (AEC) |
| Shared Package | |
| ML20084L494 | List: |
| References | |
| NUDOCS 8305230301 | |
| Download: ML20084L489 (7) | |
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Commonwealth Edison Company ONE FIRST NATIONAL PLAZA
- C H I C A G O, I L L I N O l1 40490 October 27, 1970 Dr. Peter A. Morris, Director Division of Reactor Licensing U.S. Atomic Energy Commission Washington, D.C.
20545
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Subject:
Additional information relative to the application for Construction Permit and Operating License for Quad-Cities Unit i filed under AEC Dkt 50-254
Dear Dr. Morris:
The purpose of this letter is to inform you of a small smoldering-type fire which occurred on some plywood docking material.on the lower core plate of quad-Cities Unit i reactor pressure vessel.- The potential effect of this fire on the vessel has been investigated and it has been established.that there was no detrimental effect to either the vessel or the lower core plate.
Attached hereto is Exhibit I which is our det' ailed report of the fire including construction status at the time of the fire, a description of the fire and subsequent clean-up~ opera-
'q tion, and an analysis of the fire and its effect.
In addition to three signed originals, 19 copies of 3
'NE this_i_nformation are also submitted.
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g Byron Lee, Jr.
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EXHIBIT I QUAD-CITIES STATION - UNIT 1 SEPTEMBER.27 REACTOR PRESSURE VESSEL FIRE Summary 27, 1970 a small smoldering type fire occurred on some On September temporary plywood decking material on the lower core plate of the The potential Quad-Cities Station Unit #1 Reactor Pressure Vessel.
effect of this fire on the vessel has been investigated in detail, and it has been established that the lower core plate was not affected and no detrimental effect was caused to the vessel.
However, prior to the main system hydro test of the Reactor Vessel an extensive smear test program and cleanup procedure will be performed on the interior surfaces of the vessel to ensure that no contaminates are left on the vessel interior surfaces.
Construction Status at Time of Fire The Reactor Pressure Vessel for Unit 1 was' positioned in the reactor building on June 5,1970 with the main system hydro test scheduled for Novemb er, 1970.
At the time of the fire, the major erection operation underway in the vessel was the installation of the control rod drive housings.
This installation work was proceeding on a double shif t operation.
The fire started sometime after 1:30 a.m. on the morning September 27, 1970.
The night shift effort had been of Sunday,d no erection work was underway at the time of the fire.
secured an Description of the Fire' and Cleanup Operations l
A smoldering wood fire occurred in two small areas (approximately' The-12 square feet and 4 square feet) on top of the lower core plate.
fire started from the heat released from a 1500 watt quartz type high intensity flood light which was mounted above the temporary. wood decking used on the lower core plate.
This flood light ignited either the insulation material on a welding cable coiled on the wood decking or the plywood material of the decking.
I The fire started in the north section of the lower core plate and spread to a smaller area in the northwest section.
The fire spread across a polyethylene plastic covered wooden ~ frame which was. utilized c
L during erection operations to control air currents around an optical alignment instrument.
The plastic covered frame evidently ignited
-from the initial fire area and transported the fire to the secondary fire area.
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'The following materials were consumed in the fire:
These!were 1 - Ap/proximatelyL16 wooden lower core plate covers.3 4". thick' plywood co 2" x 2" wooden frame.
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. i 2 - Approximately 40 feet of neoprene welding cable insulation.
3 - A 2 to 3 foot long section of 12" diameter Dupont plastic ventilation air duct.
4 - Approximately 80 square feet of reinforced polyethylene.
The fire was extingdished as follows:
1 - Two unsuccessful attenpts were made to extinguish the fire from below the lower core plate using a CO2 fire extinguisher.
i 2 - A third unsuccessful attempt was made from below the lower core plate with a dry chemical fire extinguisher.
Approximately 12 lbs. of this naterial was used.
3 - The fire was extinguished from above the lower core plate using domineralized water.
The fire left a deposit of black soot on the interior surface of the l
Reactor Vessel shroud in the area above the fire.
Also, the bottom l
of the vessel contained a small amount of water and bits and pieces i
of debris from the combustible material.
On the lower core structure in the fire area, black soot and coubustible products were deposited on the exposed metal surfaces.
The interior of the RPV was cleaned after the fire as follows:
1 - All loose and burned material was removed'from the vessel.
The water in the lower head region was removed through a control rod drive penetration via a drain hose.
2 - Demineralized water was used to wash down the lower core spray sparger, the interior shroud wall and the entire lower area of the vessel below the lower core structure.
3 - The areas as indicated in Item 2 were then rubbed down with acetone l-and rags and then with denineralized water containing 500 ppm Trisodiun Phosphate.
4 - The debris on the lower core plate was renoved with stainless steel j
wire brushes and stainless steel putty knives.
Attachment A details the chronology of the fire.
Analysis of the' Fire and Its Effects 1 - Sensitization Analysis -- as mentioned previously, the combustible materials involved in the fire included wood, neoprene, plastic duct,- and. polyethylene ' sheet plastic.
The. intensity of the fire can be judged by the fact that the welding cable insulation' '(neoprene 1
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rubhcr) was consumed but that the cabic itself - made up of small r
strands of copper wire - was not consuned.
This would indicate a possible upper fire tenperature limit of approxinately 1900*F.
e The aluninun housing and frame of the high intensity quartz flood light showed sone distortion and an indication that the nelting This would mean temperature of the aluminun had been reached.
p' d that the mininum fire temperature reached could have been as low as 950*F.
The temperature range is also indicated from the pyrex cover on the light which showed no indication of softening.
This fact would linit tenperatures to the 1300 - 1500*F range.
The UESC and General Electric supervisors who extinguished the fire with demineralized water both concur that the lower core plate structure did not reach significant tenperature during the fire.
Their conclusions were based on the fact that the lower core structure was only warn to the touch of their hands during and innediately after the fire, and that the water used to extinguish the fire did not steam upon contact with the lower core plate structure.
In addition, detailed inspection of the lower core plate structure indicates no discoloration or oxidation of the stainless steel.
As such, we have concluded that the lower core plate structure was not exposed to temperature conditions which would produce sensitization of the netal.
2 - Dimensional Changes -- after the fire, detailed neasurenents werc
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taken of the lower core plate structure.
These measurenents have been compared with the "as fabricated" shop neasurements established for the lower core plate structure.
With one exception, the measurenents taken af ter the fire are consistent with the "as fabricated" noasurements.
One guide tube hole in the. lower core plate within the fire area, measured slightly smaller on both dianeters (up to 0.008") than the "as fabricated" dimensions.
We have not been abic to establish a logical explanation as to why the fire would have caused an overall reduction in the size of the hole.
Accordingly, we have concluded the original "as fabricated" dinensions were likely subject to some error because the lower core plate measurements are very sensitive to anbient conditions.
In summary, our detailed inspection of th.e lower core plate structure indicates no warping, alignment, or dimensional probicas exist as a result of the fire.
3 - Analysis for Contaninants -- the materials consumed in the fire and those materials used to extinguish the fire were analyzed to determine if they contained any ingredients which might be harmful to the vessel material.
The analyses were perforned by independent consulting chemists.
The results of these analyses are tabulated below:
Sanple Chloride (as C1)
Total Sulfur (as S)
Fire extinguisher dry
~ ~5 chemical 35.00%/,
23.2 ppm *
- ppm = parts per million
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Sanple Chloride (as C1)
-Total Sulfur (as S)
Glue fron plywood 0.67%
Trace l
Air vent duct 0.060%
- 4. 3 ppm Cable insulation-0.0042%
2.8 ppm The fire extinguisher material was originally indicated to contain
" Formula - !!" as supplied by the C-0-TWO Fire Extinguisher Company.
The composition of " Formula - H" is:
92% Sodium Bicarbonate 5% Attapoulgous clay 2% Mica 1% Poly siloxane coating Upon learning of the high chloride content in the dry chemical, further discussions and investigation revealed that the fire extinguisher. had been recharged with potassium chloride.
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resultant nixture of " Formula - 11" and potassium chloride contained 35% free chlorides.
Based on the aforementioned analyses, it was determined that chlorides were the only potentially detrimental contaminant.
A smear program was instituted to determine the chloride icyc1 remaining on various portions of the vessel.
The vessel head was smeared to obtain background data as it was located on the refueling floor and was not contaminated by the fire.
The nozzles on the reactor were also taped and sealed shut from the inside and not subjected to the fire's environment.
Smear tests were also run on sone of these nozzles.
The results of the smear tests run by independent consulting chemists are tabulated below:
Location Chloride Concentration Inside llead - (background) 02 -.05 mg/sq. ft.
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Outside taped sealed main steam, feddwater, and' recirculation outlet nozzles
.01 -
03 mg/sq. ft.
Vessel wall
.03 - 0.10 mg/sq. ft.
Shroud Interior 03 - 0.10 mg/sq. ft.
Lower core plate structure 0.20 - 4.8 mg/sq. ft.
The results of this smear program indicate that the initial cleaning has reduced the chloride' residuals to an acceptable level.
l As such, we intend to continue with the control rod drive housing-installation work... Prior to the system hydro, however,.the entire vessel interior will be cleaned.using a high pressure liquid blast-technique, with any'other required measures,-and the smear program repeated.
This-procedure will be repeated until chloride levels are' reduced to background.-
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. The following additional factors are of significance in this matter:
322EE A - The control rod drive stub tubes and welds are inconel andahighchloridecontentdoesnothaveadetrimentalaalg17"$
effect on inconel.
B - Sulfur content for the materials analyzed are below the level of concern for inconel.
We have therefore concluded that the resultant contaminant level after cicaning will not result in a detrimental effect on the vessel.
The other factors, such as temperature and pressure, did not exist when the contaminants were present and as a result, the contaminants, when they were present, did not have a detrimental effect on the vessel.
4 - Preventive Measures - to preclude against a recurrence of a fire in the vessel, a fire retardant paint has been applied to the wooden blocks used as a deck on the lower core plate.
The use of high voltage quartz lamps for illumination has been discontinued.
Additional approved fire extinguishers have been located in the area and in the vessel.
Procedures for handling fires have also been reviewed and strengthened.
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Chronology The following is a complete chronology of the events which took place on Sunday, September 27, 1970, the day of the fire.
The times specified are approximate.
1:30 a.m. - Night shift stopped work in the Reactor Pressure Vessel.
At this time the RPV ventilation and electrical power supply (except lighting) t'o the RPV was shut off.
3:45 a.u. - Fire discovered by Connonwealth Ed'ison equipnent attendant while making a routine plant inspection on the Refueling Floor.
lie observed smoke coming through small openings in the temporary covering on top of the RPV.*
3:45 - 3:55 a.m. - First attempt to extinguish fire with CO -
2 3:55 a.m. - Plant construction guards notified, who in turn notified the UEGC Boilermaker Superintendent and the Cordova Fire Departnent.
4:05 a.m. - General Electric Co. Operations Superintendent notified at houe.
4:05 - 4:15-a.m. - Second attempt to extinguish fire with CO -
2 4:15 a.m. - Cordova Fire Department arrived - attempt to extinguish fire with dry chemical.
4:30 a.n. - UEGC Boilermaker Superintendent arrived and started hook up of denineralized water supply to RPV.
4:45 a.m. - General Electric Co. Operations Superintendent and Site Manager arrived.
5:40 a.m. - Fire extinguished.
- Commonwealth Edison Co. operators and General Electric Co. hired construction guards routinely patrol the plant for observation of abnormal conditions and to maintain a fire watch.
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