ML20062C877
| ML20062C877 | |
| Person / Time | |
|---|---|
| Site: | Callaway  |
| Issue date: | 11/06/1978 |
| From: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | Bryan J UNION ELECTRIC CO. |
| References | |
| NUDOCS 7811150059 | |
| Download: ML20062C877 (1) | |
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UNITED STATES NUCLEAR REGULATORY COMMISSION w
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799 ROCSEVELT ROAD
,4 OLEN ELLYN, ILLINOIS 60137 TiOV D 1978~
Docket No. 50-483 Docket No. 50-486 Union Electric Company ATIh:
Mr. John K. Bryan Vice President - Nuclear P. O. Box 149 St. Louis, Mo 63166 i
Gentlemen:
The enclosed IE Circular No. 78-18 is fcrwarded to you for infor-
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mation. No specific action is requested and no written response is required. If you desire additienal information regarding this matter, please contact t!!i*s office.
Sincerely, gj m uu -
gJanesG.KeppIer Director
Enclosures:
- 1. IE Circular No. 78-18 i'.
- 2. List of IE Circulars Issued in 1978 l
cc w/encls:
i Central Files Director, NRR/DPM Director, NRR/ DOR PDR Local PDR NSIC TIC i
Region I & IV Ms. K. Drey Hon. C. J. Frass, Chairman Missouri Public Service Commission i
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U.S. NUCLEAR REGULATORY COMMISSION 0FFICE OF INSPECTION AND ENFORCEMEFT j
REGION III i
IE Circular Ro 78-18 i
November 6,1978 l
UL FIRI TEST 1
Background
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on September 15, 1978, a fire test of a full-scale vertieni cable tray i
array was conducted at the Underwriters Laboratory (UL) near Chicago,
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Illineis. It was part of the fire protection research program managed by.Sandia Laboratories under NRC contract. The purpose of the test war.
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to demenstrate the effectiveness of area sprinklers and cable tray fire
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barriers constructed of ceramic fiber blankets in preventing damage to j
cables as a result of an exposure to a flammable liqu'.d fire. The test i
resulted in damage to some electrical cables.
l Discussion The configuration of the fire test was selected to simulate a section of a plant area with vertical cable trays containing redundant safety divisions arranged such that the redundant divisions could be simul-taneously exposed to a potential fire resulting from an inadvert.nt spill of fla==able liquid in the area. The arrangement of the cable trays and
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the designatien of the redundant tray divisions is shown in Figure 1.
l Figure 2 shows the location of the fire detectors and the three groups of sprinklers. Each of the five cable trays contained cable insulated.
f with polyvinyl chloride and was enclosed in a separated ceramic fiber blanket fire barrier from floor to ceiling in accordance with the manu-facturer's recommendations. The sprinkler and detector arrangement was j
as permitted by NFPA Code. However, no water was actually used at any t
time during this test due to the failure of some sprinkler heads to actuate, as explained below.
Each sprinkler location in the test arrangement contained three nominally identical te=perature sensing sprinkler heads with fusible links adjacent to an open sprinkler head which was connected to a manual water supply valve. The te=perature sensing heads were wired to signal when their links fused. After all three temperature sensing heads at a given loca-l tion activated, then the water supply for the open head was to be
- nually ad=itted. The sprinklers were of a type which actuate at the slow end of acceptance for reaction time. The test procedure required that all three tecperature sensing heads had to activate before water would be turned on.
In this way, it was expected to get some data on variability in the response time of identical sprinklers.
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IE Circular No. 78-15 November 6, 1978 I
e Test Details i
The test was started by igniting the two gallons of heptane that was poured into the floor pan. A fully developed fire occurred almost
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ic=ediately. The ceiling smoke detector alarmed in about 15 seconds.
l In about 50-60 seconds, two of the three te=perature sensing sprinklers located between the wall and cable trays I and 2 activated. The fire between cable trays 1, 2, 3, and 4 appeared most intense, apparently because of a chimney effect between the four trays. The flames between cable trays 3 and 5 did not appear to be so intense. The cera=1c fiber blanket absorbed some of the heptane so that after the heptane in the pan burned, most of the fin =e seemed to come from the bottom outside l
surface of the cera=ic fiber blanket. No additional te=perature sensing sprinkler heads at any location activated; thus, the sprinkler water supply was not turned on for an'; of the three sprinkler locations.
The apparent slov response of the third temperature e, sing sprinkler is being investigated, since this was not intended to be slow response sprinkler.
At about 3 minutes into the test there was an indication of a short circuit in cable tray 3, which was probably caused by the fire. After 5-7 minutes the height of the flames appeared to subside; however, r
residual flames continued for about 40 minutes.
Preliminary Results and Analyses l
r Preliminary information indicates that the flam=able liquid or flames penetrated the protective barriers at the bottom of the vertical trays and caused fire damage to the polyvinyl chloride insulation on cables 7
in four of the five trays.
f On subsequent 500-volt zegger tests, it was found that another cable in tray 2 had also experienced some damage, as evidenced by a conductor to ground short.
i The most probable cause of the fire damage in certain cable trays appears l
to be related to the absorption or seepage of heptane under the cera=le fiber blanket at the juncture with the floor. Once the heptane entered the interior regions of the cable tray, then ignition apparently occurred via the small opening at the floor or through a vapor / air path within the joints. There is some indication that some cable da= age was caused by absorption of heptane on the inside of the barrier (vicking effect) and its ignition which heated a cable tray ladder rung, causing da= age I
to r. cable in contact with the rung. The ingress of the heptane inte the ceramic fiber needs to be further evaluated since this appears to be the most significant failure mode.
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4 IE Circular No. 78-18 November 6,1978 Tentative Conclusions The test results are still being analyzed, and it would be premature te establish fir = conclusions at this time; hcvever, the results now available indicate that the following areas of the fire protection progra: need close consideration:
1.
To protect against spills of fla==able liquids, barriers or curbs may be needed to prevent entry of the fla==able liquid behind fire barriers. A vick effect may also need to be considered in the desigr.
of fire barriers.
2.
Some small fires may not actuate sprinkler heads. To redece this possibility in sprinkler systems to be installed, fast response sprinkler heads should be considered (less than apprcximately 3 minutes in the UL Standard 199 " Automatic Sprinklers for Fire Protection Service").
3.
The location cf the fire detection devices and the sprinkler heads relative to el e fire and components being protected is of great importance. The path of the air movenent in the area influences the actuatier. of such devices and should be considered in the system layout.
The final results of this test will be issucd when the analysis of the test is ce=plete.
This circular is being issued for information only. No specific actien is requested and ne written response is required. If you desire addi-tional information regarding this matter, contact the Director of the appropriate NRC Regional Office.
Attachments:
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P IE Circular No. 78-18 November 6, 1978 LISTING OF IE CIRCULARS ISSUED IN 1978
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r Circular Subject Date Issued To l
No.
of Issue 78-01 Loss of Well Logging 4/5/78 All Eelders of Source Well Logging Source Licenses 78-02 Proper Lubricating 011 4/20/78 All Holders of for Terry Turbines Reactor OLs or cps 78-03 Packaging Greater Than 5/12/78 All Holders of f
Type A Quantities of heactor OLs, cps,
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Low Specific Activity Fuel Cycle, Radioactive Material Priority I Material for Transport and Waste Disposal i
Licenses 78-04 Installation Error That S/15/78 All Holders of Could Prevent Closing of Reactor OLs or Fire Doors CPa r
78-05 Inadvertent Safety Injection 5/23/78 All Holders of During Cooldown Reactor OLs or cps f
78-06 Potential Com=en Mode 5/23/78 All Holders of I
Flooding of ECCS Equipment Reactor OLs or Rooms at BWR Tacilities cps 78-07 Da= aged Components of a 5/31/78 All Holders of Bergen-Paterson Series Reactor OLs or 25000 Eydraulic Test cps Stand 78-08 Environnental Qualification 5/31/78 All Holders of of Safety Related Equipment Reactor OLs or at Nuclear Power Plants cps 78-09 Arcing of General Electric 6/5/78 All Holders of Company Size 2 Contactors cps f
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IE Circular No. 78-18 November 6, 1978 l
LISTING OF IE CIRCULARS ISSUED IN 1978 Circular Subj ect Date of Issued to No.
Issue i
r 78-10 Control of Sealed 6/14/78 All Medical Sources Used in Licensees in
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Radiation Therapy Categories G I
and G1 78-11 ~
Recirculation M-G 6/15/78 All Holders of i
Set Overspeed Stops BWR OLs or cps r
78-12 EPCI Turbine Control 6/30/78 All Holders of Valve Lift Rod Bending BWR OLs or cps i
for plants with i
EPCI Terry Turbine
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78-13 Ineperability of Multiple 7/10/78 All Holders of i
Service Water Pumps Reactor OLs And cps except for plants located in: AL, AK, CA, FL, GA, LA, MS, i
SC 1
78-14 HPCI Turbine Reversing 7/12/78 All Holders of BWR k
Chamber Hold Down Bolting OLs or cps for plants with a HPCI i
Terry Turbine j
excepting Duane
-s Arnold and Monticelle i
78-15 Checkvalves Fail to 7/20/78 All Holders of i
Close In Vertical Reactor OLs or cps Position 78-16 Limitorque Valve 7/26/78 All Holders of f
i Actuators Reactor OLs or cps 78-17 Inadequate Guard Training /
10/13/78 All Holders of
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Qualification and Falsified and applicants l
Training Records for Reactor OLs.
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