ML20062C899
| ML20062C899 | |
| Person / Time | |
|---|---|
| Site: | Kewaunee  |
| Issue date: | 11/06/1978 |
| From: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | James E WISCONSIN PUBLIC SERVICE CORP. |
| References | |
| NUDOCS 7811150072 | |
| Download: ML20062C899 (1) | |
Text
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UNITED STATES c
.- t NUCLEAR REGULATORY COMMISSION
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\\J ll0V G 1978-Docket No. 50-305 hisconsin Public Service Corporation ATTN:
Mr. E. W. James Senior Vice President Power Generation and Engineering P. O. Box 1200 Green Bay, WI 54305 Gentlemen:
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The enclosed IE Circular No. 78-18 is forwarded to you for infor-mation. No specific action is requested and no written response is required.
If you desire additional information regarding this matter, please contact this office.
Sincerely, u
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[ aces'G. (el!bfer _
Director
Enclosures:
- 1. IE Circular No. 78-18
- 2. List of IE Circulars Issued in 1976 cc w/encls:
Mr. C. Lucca, Plant Superintendent Central Files Director, NRR/DPM Director, NRR/ DOR PDR Local PDR NSIC TIC n
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e U.S. NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCE!tEPT REGION III IE Circular Ro 78-16 UL FIRI TEST November 6, 1978
Background
on September 15, 1978, a fire test of a full-scale vertical cable tray array was conducted at the Underwriters Laberatory (UL) near Chicago, Illineis.
It was part of the fire protection research program managed by Sandia Laboratories under NRC contract. The purpose of the test was te de enstrate the effectiveness of area sprinklers and cable tray fire barriers constructed of ceramic fiber blankets in preventing damage to
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cables as a result of an exposure to a flammable liquid fire. The test resulted in damage te sete electrical cables.
Discussien The configuration of the fire test was selected to simulate a section of a plant area with vertical cable trays centaining redundant safety divisions arranged such that the redundant divisions could be simul-taneously exposed to a potential fire resulting from an inadvertent spill of flat =able liquid in the area. The arrange =ent of the cable trays and the designation of the redundant tray divisions is shewn in Figure 1.
Figure 2 shows the locatien 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 cera=ic fiber blanket fire barrier from floor to ceiling in accordance with the manu-facturer's reco=cendations. The sprinkler and detector arrangement was as per=itted by NFPA Code. However, no water was actually used at any
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time during this test due tc the failure of some sprinkler heads to actuate, as explained below.
Each sprinkler location in the test arrangecent centained three nominally identical temperature sensing 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. After all three temperature sensing heads at a given loca-tien activated, then the water supply for the open head was to be manually 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 te:perature 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 respense time of identical sprinklers.
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IE Circular No. 78-16 Nove=ber 6, 1978 Test Details The test was started by igniting the twe gallons of heptane that was poured into the floor pan. A fully developed fire occurred almost ic=ediately. The ceiling smoke detector alarmed in about 15 seconds.
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=ic fiber blanket absorbed some of the heptane so that after the heptane in the pan burned, most of the flame seemed to co=e from the botto= outside 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 any of the three sprinkler locations.
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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 5-7 minutes the height of the flames appeared to subside; however, residual flames continued for about 40 minutes.
Prelicinary Results and Analyses Preliminary information indicates that the.'la==able liquid or fla:es penetrated the protective barriers at the bottom of the vertical trays and caused fire da= age to the polyvinyl chloride insulation on cables l
it four of the five trays.
l Or subsequent 500-volt megger tests, it was found that another cable in
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tray 2 had also experienced some da=aga, as evidenced by a conductor to ground short.
The most probable cause of the fire da: age in certain cable trays appears to be related to the absorption or seepage of heptane under the ceratic 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 vaper/ air path within the joints. There is sece indication that some cable damage 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 to a cable in contact with the rung. The ingress of the heptane into the cera:ic 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 to establish firm conclusions at this time; however, the results now available indicate that the following areas of the fire protection progra: need close consideration:
1.
To protect against spills of flam=able liquids, barriers or curbs may be needed to prevent entry of the flam=able liquid behind fire barriers. A vick effect may also need to be considered in the design of fire barriers.
2.
Some s=all fires may not actuate sprinkler heads. To reduce this possibility in sprinkler systens to be installed, fast respense 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 importance. The path of the air movement in the area influences the actuation of such devices and should be considered in the syste: 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 infor=ation regarding this matter, contact the Director of the appropriate NRC Regional Office.
Attachments:
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IE Circular No. 78-18 November 6, 1978 LISTING OF IE CIRCULARS ISSUED E 1978 Circular Subject Date Issued To No.
of Issue 78-01 Loss of Well Logging 4/5/78 All Helders 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 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 Coeldown Reactor OLs er cps 78-06 Potential Coc=en Mode 5/23/78 All Holders of Flooding of ECCS Equipnent Reactor OLs og Roons at Bk'R Pacilities cps 78-07 Danaged Conponents of a 5/31/78 All Holders cf Bergen-Paterson Series Reactor OLs or 25000 Eydraulic Test cps Stand 78-08 Environ = ental Qualificatien 5/31/78 All Holders cf of Safety Related Equipnent Reactor OLs or at Nuclear Pcwer Plants cps 78-09 Arcing of General Electric 6/5/78 All Eolders of Conpany Size 2 Contactors cps
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IE Circular No. 78-18 November 6, 1978 LISTING OF IE CIRCULARS ISSUED IN 1978 Circular Subj ect Date of Issued to No.
Issue 78-10 Centrol of Sealed 6/14/78 All Medical Sources Used in Licensees in Radiation Therapy Categories G and G1 78-11 Recirculation M-G 6/15/78 All Holders of Set Overspeed Stops BWR OLs or cps 78-12 HPCl Turbine Control 6/30/78 All Holders of Valve Lift Rod Bending BWR OLs or cps for plants with EPCI Terry Turbine 78-13 Ineperability of Multiple 7/10/78 All Holders of Service Water Pumps Reactor OLs and cps except for plants located in: AL, AK, CA, FL, GA, LA, MS, SC 78-14 EPCI Turbine Reversing 7/12/78 All Helders of SWR Cha=ber Hold Down Bolting OLs or cps for plants with a EPCI l
i Terry Turbine excepting Duane l
Arnold and Monticello 78-15 Checkvalves Tail to 7/20/78 All Holders of Clo.se In Vertical Reactor OLs er cps Positien 78-16 Li=iterque valve 7/26/78 All Holders of Actuators Reactor OLs or cps 78-17 Inadequate Guard Training /
10/13/78 All Holders of Qualification and Falsified Training Records and applicants for Reactor OLs.
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