ML20148J006

Forwards IE Circular 78-18

ML20148J006
Person / Time
Site:	Grand Gulf
Issue date:	11/06/1978
From:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
To:	Stampley N MISSISSIPPI POWER & LIGHT CO.
References
NUDOCS 7811150094
Download: ML20148J006 (1)

Text

. - - - - . _ - _ _ - _ . - - . _ _ _ _ _ _ _ _ _ __ - __________ ___ ___ _ _ _ _ _ _ _ _ _ _

s t 6" " GW UNITED ST ATES -

1. f o NUCLEAR REGULATORY COMMISSION ,, g h- ' ' E 101 M ARIETT A STRE E T, N W ATL ANT A, GEORGI A 30303

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% ,',$ . / NOV 1978 In Reply Refer To:

RII:JP0 50-416, 50-417 Mississippi Power and Light Company Attn: Mr. Norris L. Stampley Vice President of Production P. O. Box 1640 Jackson, Mississippi 39205 Centlemen:

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

Sincerely,

/'

/

/ /,

/ames J P. N'Reilly

~ Director l

Enclosures:

i 1. IE Circular 78-18

2. List of IE Circulars Issued in 1978 cc w/ enc 1:

Mr. W. L. Nail, Plant Superintendent P. O. Box 756 Port Gibson, Mississippi 39150 7811150D99 E _ - - - - _ - - - _ _ _ _ - _ - _ _

UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEENT WASHINGTON, D. C. 20555 November 6, 1978 IE Circular 78-18 UL FIRE TEST

Background

On September 15, 1978, a fire test of a full-scale vertical cable tray array was conducted at the Underwrit ers Labora tory (UL) near Chicago, Illinois. It was part of the fire protection research program managed by Sandia Laboratories under NRC contract. The purpose of the test was to demonstrate the effectiveness 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 flam=able liquid fire. The test resulted in damage to some electrical cables.

Discussion The configuration of the fire test was selected to siculate 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 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 shows 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 recommendations. 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 below.

Each sprinkler location in the test arrangement contained three noninally identical temperature sensing sprinkler heads wit h f usible links adj acent to an open sprinkler head which was connected to a manual water supp1v valve. The temperature sensing heads were wired to signal when their links fused. Af t er all three t emperat ure 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 actuate 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 be turned on. In this way, it was expected to get some data on variability in the response time of identical sprinklers.

November 6, 1978 IE Circular 78-18 Test Details The test was started by igniting the two gallons of heptane that was poured.into'the floor pan. A fully developed fire occurred almost immediately. The ceiling smoke 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 No additional temperature sensing surface of the ceramic fiber blanket.

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 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 i 5-7 minutes the height of the flames appeared to subside; however, residual flames continued for about 40 minutes.

Preliminary Results and Analyses l Preliminary information indicates that the flammable liquid or flames the bottom of the vertical trays penetrated the protective barriers at .;

and caused fire damage to the polyvinyl chloride insulation on cables l in four of the five trays.

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

The most probable cause of the fire damage in certain cable trays appears f heptane under the ceraefe

.to be related to.the absorption or seepage o Once the heptane entered fiber blanket at the juncture with the floor.

the interior regions of the cable tray, then ignition apparently occurred via the email 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 (vicking effectl l and its ignition which heated a cable tray ladder rung, causing dLaage

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to a. cable in contact with the rung. The ingress of the heptane into l

.the ceramic fiber needs to be further evaluated since this appears to be the most significant failure mode.

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November 6, 1978 IE Circular 78-18 Tentative Conclusions The test results are still being analyzed, and it would be premature to establish firm conclusions at this time; however, the results now available indicate that the following areas of the fire protection prograe need close consideration:

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

2. Some small fires may no- actuate sprinkler heads. To reduce this possibility in sprinklet systems to be installed, fast response sprinkler heads should te considered (less than approximately 3 minutes in the UL Star.3ard 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 importance. The path of the air movement in the area influences the *ctuation of such devices and should be considered in the system layout.

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

This circular is being issued for information only. No 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:

1. Figure 1

2. Figure 2

IE Circular No. 78-18 November 6, 1978 LISTING OF IE CIRCULARS ISSUED IN 1978 Circular Subj ec t Date Issued To No. of Issue 78-01 Loss of Well Logging 4/5/78 All Holders of Source Well Logging Source Licenses 78-02 Proper Lubricating 011 4/20/78 All Holders of j for Terry Turbines Reactor OLs or cps 78-03 Packaging Greater Than 5/12/78 All Holders of Type A Quantities of Reactor OLs, cps, Low Specific Activity Fuel Cycle,

Radioactive Material Priority I Material for Transport and Waste Disposal Licenses 78-04 Installation Error That 5/15/78 All Holders of Could Prevent Closing of Reactor OLs or Fire Doors cps 78-05 Inadvertent Safety Injection 5/23/78 All Holders of During Cooldown Reactor OLs or cps 78-06 Potential Common Mode 5/23/78 All Holders of Flooding of ECCS Equipment Reactor OLs or Rooms at BWR Facilities cps 78-07 Damaged Components of a 5/31/78 All Holders of Bergen-Paterson Series Reactor OLs er 25000 Hydraulic Test cps Stand 78-08 Environmental 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 Enclosure Page 1 of 2

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t IE Circular No. 78-18 November 6, 1978 LISTING OF IE CIRCULARS ISSUED IN 1978 Circular Subject Date of Issued to No. Issue -

78 .10 Control of Scaled 6/14/78 All Medical Sources Used in Licensees in Radiation Therapy Categories C and G1 78-13 Recirculation M-G 6/15/78 All Hsiders of Set Overspeed Stops Bk'R OLs or cps 78-12 HPCI Turbine Control 6/30/78 All Holders of Valve Lift Rod Bending  ??R OLs or cps for plants with HPCI Ter ry Turbine 78-13 Inoperability of Multiple 7/10/78 All Holders of Service Water Pumps Reactor OLs and cps except for plants located in: AL, AF.,

CA, FL, GA, LA, MS, SC 78-14 HPCI Turbine Reversing 7/12/78 All Holders of Bk?

Chamber Hold Down Bolting OLs or cps for plants with a HPC Terry Turbine except ing. Duane Arnold and Monticelle 78-15 Checkvalves Fail to 7/20/78 All Holders cf Close In Vertical Reactor OLs or cps Position 78-16 Limitorque Valve 7/26/78 All Holders of Actuators Reactor OLs or cps l

78-17 Inadequate Guard Training / 10/13/78 All Holders of Qualification and Falsified and applicants Training Records for Reactor OLs.

Enclosure Page 2 of 2

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