ML17138A441
| ML17138A441 | |
| Person / Time | |
|---|---|
| Site: | Susquehanna  |
| Issue date: | 11/06/1978 |
| From: | Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| To: | Curtis N PENNSYLVANIA POWER & LIGHT CO. |
| References | |
| NUDOCS 7811290142 | |
| Download: ML17138A441 (6) | |
Text
UNITED STATES NUCLEAR REGULATORY COMMISSION REGION I 63 I PARK AVENUE KING OF PRUSSIA, PENNSYLVANIA 19406 Docket Nos.
50-387 50-388 November 6, 1978 Pennsylvania Power 8 Light Company ATTN:
Mr. Norman W. Curtis Vice President Engineering and Construction (N-4) 2 North Ninth Street Allentown, Pennsylvania 18101 Gentlemen:
The enclosed IE Circular No. 78-18 is forwarded to you for informa-tion.
No specific action is requested and no written response is required.
If you desire additional information regarding this matter, please contact this office.
Sincerely, Director
Enclosures:
l.
IE Circular No. 78-18 2.
List of IE Circulars Issued in 1978 cc w/encls:
A. R. Sabol,
- Manager, Nuclear guality Assurance W. E. Barberich; Licensing Engineer
UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D. C.
20555 UL FIRE TEST
Background
IE Circular 78-18 Date:
November 6, 1978 Page 1 of 3 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'imulate 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 manufacturer'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 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 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.
0 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 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 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'nto 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.
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.
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 a cable in contact with the rung.
The ingress of the heptane into the ceramic fiber needs to be further evaluated since this appears to be the most significant failure mode.
Q 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 coriclusions 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 systems 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 importance.
The 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
ENCLOSURE 2
IE ircular No. 78-18 Date:
November 6, 1978 Page 1 of 2 LIST OF IE CIRCULARS ISSUED IN 1978 Circular No.
78-01 Subject Loss of Well Logging Source First Date of Issue 4/14/78 Issued To All Holders of Well Logging Source Licenses 78-02 Proper, Lubricating Oil 4/20/78 for Terry Turbines All Power Reactor Facilities with an Operating License (OL) or Construction Permit (CP) 78-03 Packaging Greater Than Type A guantities of'ow Specific Activity Radioactive Material
.for Transport 5/12/78 All Power Reactor Facilities with an OL or CP; and all Fuel Cycle, Priority I Materials and Waste Disposal Licensees 78-04 Installation Errors That 5/18/78 Could Prevent Closing of Fire Doors All Power Reactor Facilities with an OL or CP 78-05 78-06 Inadvertent Safety Injection During Cooldown Potential Common Mode Flooding of ECCS Equipment Rooms at BWR Facilities 5/26/78 5/31/78 All PWR Power Reactor Facilities with an OL or CP All Power Reactor Facilities with an OL or CP 78-07 78-08 Damaged Components on a
5/31/78 Bergen-Paterson Series 25000 Hydraulic Test Stand Environmental gualifica-5/31/78 tion of Safety-Related Electrical Equipment at Nuclear Power Plants All Power Reactor Facilities with an OL or CP All Power Reactor Facilities with an OL or CP
ENCLOSURE 2 (Continued)
LIST OF IE CIRCULARS ISSUED IN 1978 IE Circular No. 78-18 Date:
November 6, 1978 Page 2 of 2 Circular Subject No.
First Date of Issue Issued To 78-09 78-10 Arcing of General Electric 6/8/78 Company NEMA Size 2
Contactors Control of Sealed Sources 6/14/78 Used in Radiation Therapy All Power Reactor Facilities with an OL or CP All Institutional Medical Licensees 78-11 78-12 78-13 78-14 78-15 78-16 78-17 Recirulation M-G Set Overspeed Stops HPCI Turbine Control Valve Lift Rod Bending Inoperability of Multiple Service Water Pumps HPCI Turbine Re-versing Chamber Hold Down Bolting Tilting Disk Check Valves Fail to Close with Gravity in Vertical Position Limitorque Valve Actuators Inadequate Guard Training/gualification and Falsified Training Records 6/15/78 6/30/78 7/10/78 7/17/78 7/24/78 7/26/78 10/13/78 All BWR Power Reactor Facilities with an OL or CP All Power Reactor Facilities with an OL or CP having a
HPCI Terry Turbine All Power Reactor Facilities with an OL or CP All Power Reactor Facilities with an OL or CP having a
HPCI Terry Turbine excepting Duane Arnold and Monticello All Power Reactor Facilities with an OL or CP All Power Reactor Facilities with an OL or CP All Power Reactor Facilities with an OL; Susquehanna 1
5 2,
- Shoreham, and Salem 2