ML20062D373
| ML20062D373 | |
| Person / Time | |
|---|---|
| Site: | Fort Saint Vrain  |
| Issue date: | 11/06/1978 |
| From: | Seyfrit K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| To: | Millen C PUBLIC SERVICE CO. OF COLORADO |
| References | |
| NUDOCS 7811220121 | |
| Download: ML20062D373 (1) | |
Text
{{#Wiki_filter:* x o N UNITED STATES =- [ a Nac,'#o NUCLEAR REGULATOR 4Y COMMISSION [ ',F REGION IV n 611 RYAN PLAZA DRIVE, SUITE 1000 2. L %, Jg.! j AR LINGTON, TEX AS 76011 November 6, 1978 Docket No. 50-267 Public Service Company of Colorado ATTN: Mr. C. K. Millen Senior Vice President Post Office Box 840 Denver, Colorado 80201 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 information regarding this matter, please contact this office. Sincerely, n' n i /. of *.*o( [.; V =* .f:
- l;
,;f s... Karl V. Seyfrit Director
Enclosures:
1. M Circular 78-18 2. List of IE Circulars Issued in 1978 i o 0 e 7811220lJ.}. 3 L
i V UilITED STATES fiUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEf1ENT WASHINGTON, D. C. 20555 IE Circular 78-18 Date: November 6, 1978 Page 1 of 3 UNDERWRITERS LABORATORY FIRE TEST
Background:
On September 15, 1978, a fire test of a full-scale vertical cable tray array was conducted at the Underwriters Laboratory (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 flammable liquid fire. The test resulted in damage to some electrical cables. 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 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 3 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 recomendations. 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 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-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 be turned on. In this way, it was expected to gat some data on the variability in the response time of identical sprinkler heads.
IE Circular'78-18 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 flcor pan. A-fully developed fire occurred almost immediately. The ceiling smoke detector alanned 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 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, residua 1 ' flames continued for about 40 minutes. Preliminary Results and Analyses. Preliminary information indicates that the flammable 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 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 to ground short circuit. The most probable cause of the fire damage in certain cable trays appears to be relattJ 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 a cable in contact with the rung. The ingres's of the heptane into the' ceramic fiber needs to be further evaluated since this appears to be the most significant failure mode.
.y IE Circular 78-18 Date: November 6, 1978 Page 3 of 3 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 program 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 not actuate ' sprinkler heads. To reduce this possibility in sprinkler sys~tems 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 fir ? detection devices and the sprinkler heads relative to the fire and components being protected is of great importance. TLu path of the air movement in the area influences the actuation 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
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..... ~ IE Circular No. 78-18 November 6, 1978 LISTING OF IE CIRCULARS ISSUED IN 1978 Circular Subject First 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 4/20/78 All Holders of Oil for Terry Turbines Reactor Operating Licenses (OL) or Construction 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 Permits (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 (0L) or Doors Construction Permits (CP) 78-05 Inadvertent Safety 5/23/78 All Holders of Injection During Cooldown Reactor Operating Licenses (OL) or Construction Permits (CP) 78-06 Potential Common 5/25/78 All Holders of l Mode Flooding cf i ECCS Eauioment Reactor Operating Licenses (OL) or Rooms at B',!R Construction Facilities Permits (CP) 78-07 Damaged Components 5/31/78 All Holders of Of a Bergen-Paterson Reactor Operating Series 25000 Hydrau-Licenses (OL) or lic Test Stand Construction Permits (CP) Enclosure Page 1 of 3
4 IE Circular No. 78-18. 4 November 6, 1978 78-14 HPCI Turbine Reversing 7/12/78 All Holders of I Chamber Hold Down BWR Operating Bolting Licenses (OL) or Construction Permits (CP) for plants with a HPCI Terry Turbine excepting Duane - Arnold and - Monticello i 78-15 Tilting Disc Check 7/20/78 All-Holdars of Valves Fail to Close Reactor Operating With Gravity in Licenses (0L) or Vertical Position Construction Permits (CP) 78-16 Limitorque Valve 7/26/78 All Holders of Actuators Reactor Operating Licenses (0L) or Construction Permits (CP) 78-17 Inadequate Guard 10/13/78 All Holders of Training /Qualifica-and applicants tion and Falsified for Reactor Training Records Operating Licenses (0L). i l i Enclosure l. Page 3 of 3 L}}