ML20148M726

Forwards IE Circular#78-18,UL Fire Test. W/Encl ANO:7811150002

ML20148M726
Person / Time
Site:	Arkansas Nuclear
Issue date:	11/06/1978
From:	Seyfrit K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
To:	Cavanaugh W ARKANSAS POWER & LIGHT CO.
References
NUDOCS 7811220117
Download: ML20148M726 (1)

Text

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. , /2LA gS RFG UNITED STA TEC g 'o NUCLEAR REGULATORY COMMISS.ON 8' 3 REGION IV 5 k*;],+y o*

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• • • • • November 6, 1978 Docket Nos. 50-368 50-313 l 7gis DOCUMEUT CONTNNS Arkansas Power and Liaht Company POOR QUAUTY PAGESJ ATTN: Mr. William Cavanaugh III i Executive l'irector of Generation and Construction Post Office Box 551 Little Rock, Arkansas 72203 Gentlemen:

The enclosed IE Circular 78-18 is forwarded to you for information. No specific action is requested and no written response is required. If you desire additional infonnation regarding this matter, please contact this office.

Sincerely,

- ->/ ., j /. '

'A}l-l tf-l). 3 'j -1 Karl V. Seyfrit' Director

Enclosures:

1. IE Circular 78-18

2. List of IE Circulars Issued in 1978 l

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e UNITED STATES NUCLEAR REGULATORY COMMISSIO:1 0FFICE OF INSPECTION AND EilFORCEMENT WASHINGTON, D. C. 20555 IE Circular 78-18 Da te : flovember 6,1978 Page 1 of 3 UNDER'.iRITERS LABORATORY FIRE TEST

Background:

On September 15, 1978, a fire test of a full-scale vertical cable tray array was conductui at the Underwriters Laboratory (UL) near Chicago, i Illinois. It was part of the fire protection research program managed by Sandia Laboratories under th(C contract. The purpose of the test was to demonstrate the ef fec.tiveness of area sprinklers and cable tray fire barriers constructed of ceramic fiber blankets in preventing damage to cables as a result of an exposure to a flammable liquid fire. The test resulted in damage te some electrical cables.

Discussion:

The configuration of the fire test was selected to simulate a section of a pldnt area with vertical cable trays containing redundant safety divisions arranged such that the redundant divisions could be simul-taneously expose <l to a potential fire resul Ling from an inadvertent spill of flammable liquid in the area. The arrangement of the cable trays and the designation of the redundant tray divisions is shown in Figure 1.

Figure 2 sho',is the location of the fire detectors and the three groups of sprinklers. Each of the five cable trays contained cable insulated 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 recoamendations. The sprinkler and detector arrangement was as permitted by NFPA Code. However, no water was actually used at any time during this test due to the failure of some sprinkler heads to actuate, as explained belo',i.

Ecch sprinkler location in the test arrangement contained three nominally identical temperature .;ensing sprinkler heads with fusible links adjacent to an open sprinkler head which was connected to a manual water supply valve. The temperature sensing heads were wired to signal when their links fused. Af ter all three temperature sensing heads at a given loca-tion activated, then the water supply for the open head was to be manually admitted. The sprinklers were of a type which activate at the slow end of acceptance for reaction time. The test procedure required that all three temperature sensing heads had to activate before water would bm turned on. In this way, it was expected to get some data on the variabilit.y in the response time of identical sprinkler heads.

IE Circular 78-13 Date: November 6, 1978 Page 2 of 3 Test Details:

The test was started by igniting the two gallons of heptane that were poured into the floor pan. A fully developed fire occurred almost immediately. The ceiling sraoke detector alarmed in about 15 seconds.

In about 50-60 seconds, two of the three temperature sensing sprinklers located between the wall and cable trays 1 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 ceramic fiber blanket absorbed some of the heptane so that after the heptane in the pan burned, most of the flame seemed to come from the bottom outside surface of the ceramic fiber blanket. No additional temperature sensing sprinkler heads at any location activated; thus, the sprinkler water supply was not turned on for any of the three sprinkler locations.

The apparent slow response of the third temperature sensing sprinkler is being investigated, since this was not intended to be a slod 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 huight of the flames appeared to subside; however, residual flames continued for about 40 minutes.

Preliminary Results and Analyses:

Preliminary information indicates that the flammable liquid or flames i penetrated the protective barriers at the bottom of the vertical trays i and caused fire damage to the polyvinyl chloride insulation on cables in four of the five trays.

On subsequent 500-volt riegger tests, it was found that another cable in tray 2 had also experienced some damage, as evidenced by a conductor to ground short circuit.

The most probable cause of the fire damage in certain cable trays appears to be related to the absorption or seepage of heptane under the ceramic 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 damage was caused by absorption of heptane on the inside of the barrier (wicking effect) and its ignition which heated a cable tray ladder rung, causing damage to e cable in contact with the rung. The ingress of the heptana into the ceramic fiber needs to be further evaluated since this appears to be the most significant failure mode.

IE Circular 78-18 Date: flovember 6, 1978 Page 3 of 3 Tentative Conclusions The test results are still being analyzed, and it viould be prenature to establish firm conclusions at this tim 2; however, the resul ts no'.t available indicate that the following areas of the fire protection program need close consideration:

1. To protect against spills of flannable liquids, barriers or curbs may be necded to prevent entry of the flammable liquid behind fire barriers. A wick ef fect may also need to be considered in the design of fire barriers.

2. So:ce amell fires may not actuate sprinkler heads. To reduce this possibility in sprinkler system; to be installed, fast response sprinkler heads should be considered (less than approximately 3 minutes in the UL Standard 199 " Automatic Sprinklers for Fire Protection Service").

3. The location of the fire detection devices and the sprinkler heads relative to the fire and components being protected is of great i importance. The path of the air movement in the area influences the actuat. ion of such devices and should be considered in the l system layout.

The final results of this test will be issued when the analysis of the tes t is complete.

This circular is being issued for information only, ilo specific action is requested and no 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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2. Figure 2

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IE Circular I!o. 78-18 November 6, 1978 LISTIllG OF IE CIRCULARS ISSUED Ifl 1978 Circular Subject First Date Issued To No. Of Issue 78-01 Loss of !! ell Logging 4/5/78 All Holders of Source Well Logging Source Licenses 78-02 Proper Lubricating 4/20/78 All Holders of Oil for Terry Reactor Operating Turbines Licenses (OL) or Cons truc tion Permits (CP) 78-03 Packaging Greater 5/12/78 All Holders of Than Type A Reactor Operator Quantities of Low Licenses (OL),

Specific Activity Construction Radioactive Material Permi ts (CP), Fuel for Transport Cycle, Priority I

' Material and Waste Disposal Licenses 78-04 Installation Error 5/15/78 All Holders of That could Prevent Reactor Operating Closing of Fire Licenses (OL) or Doors Cons truc tion Permits (CP) 78-05 Inadvertent Sa fety 5/23/78 All Holders of Injection During Reactor Operating Cooldoun Licenses (OL) or Construction Permits (CP) 78-06 Potential Common 5/25/78 All Holders of Mode Flooding of Reactor Operating ECCS Eauipment Licenses (OL) or Rooms a t C'.M Construction Facil i ties Permits (CP) 78-07 Damaged Componentt, 5/31/78 All Holders of Of a Bergen-Paterson Reactor Ooerating Series 25000 Hydrau- Licenses (OL) or lic Test Stand Construction Permits (CP)

Enclosure Page 1 of 3

IE Circular tio. 78-18 flovember 6,1978 78-03 Environiaental Quali- 5/31/78 All Holders of fication of Safety- Reactor Operating Related Equipment Licenses (OL) or at fluclear Power Construction Plants Permits (CP) 78-09 Arcing of General 6/5//8 All Holders of Electric Company Reactor Operating Size C Contactors Licenses (OL) or Construction Peraits (CP) 78-10 Control of Sealed 6/14/78 All fledical Sources Used in Licensees in Radiation Therapy Categories G and G1 78-11 Recirculation 11-G 6/15/78 All Holders of Set Overspeed Stop CWR Operating Licenses (OL) or Construction Permits (CP) 78-12 HPCI Turbine Control 6/30/78 All Holders of Valve lif t P.cd BWR Operating Bending Licenses (0L) or Construction Permits (CP) with Similar HPCI Design 78-13 Inoperability of 7/10/78 All Holders of Service Water Pumps Reactor Operating Licenses (OL) or Construction Permits (CP) except for plants located in: AL, AK, CA, FL, GA, LA,ils, SC i

Enclosure Page 2 of 3

IE Circular No. 78-18 Noveraber 6,1978 78-14 HPCI Turbine Reversing 7/12/78 All Halders of Chamber Hold Down BWR Operating Bol tin 9 Licenses (OL) or Cons truction Peraits (CP) for ,

plants with a HPCI Terry Turbine excepting Duane Arnold and Monticello 78-15 Tilting Disc Check 7/20/78 All Holders of Valves Fail to Close Reactor Operating With Gravity in Licenses (OL) or Vertical Position Cons truc tion Permits (CP) 78-16 Limitorque Valve 7/26/78 All Holders of Ac tua tors Reactor Operating Licenses (OL) or Construction Permits (CP) 78-17 Inadequate Guard 10/13/78 All Holders of - -

Training /Quali fica- and applicants tion and Falsified for Reactor Training Hecords Operating Licenses (OL).

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