ML20148J414
| ML20148J414 | |
| Person / Time | |
|---|---|
| Site: | 05000463, 05000464 |
| Issue date: | 10/26/1978 |
| From: | Desylva D, Gray J, Linenberger G MIAMI, UNIV. OF, CORAL GABLES, FL, Atomic Safety and Licensing Board Panel, NRC OFFICE OF THE EXECUTIVE LEGAL DIRECTOR (OELD) |
| To: | Clark H Atomic Safety and Licensing Board Panel |
| Shared Package | |
| ML20148J420 | List: |
| References | |
| NUDOCS 7811160001 | |
| Download: ML20148J414 (1) | |
Text
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4 _
UNITED STAT.ES -
3S: NUCLEAR HEGULATORY COMMISSIOM -
WASHINGTOi% D. C. 20055 Qi, October 26, 1978 i Mr. Hugh K. Clark, Chairman Dr. Donald P. deSylva l P. O. Box 127A Associate Professor of Marine Science Kennedyville, Maryland 21645 Rosentiel School of Marine and Atmospheric Science ,
Mr. Gustave A'. Linenberger University of Miami ,,
Atomic Safety and Licensing Board Miami, Florida 33149 U.S. Nuclear Regulatory Commission -
i Washington, D . C . 20555
'T[@b - !
,.s Y In the Matter of Philadelphia Company lly ,hg[cY ,,
(Fulton Generating Station, Units l'and 2) m -
' Docket Nos. 50-463 and 50-464 h4 #
cp ,aUes Gentlemen:
Enclosed is a memorandum from the Director of the Office of Nuclear Reactor Regulation to the Commissioners dated September 29, 1978 discussing the i
, results of a recently conducted fire protection research test by the Under-writers Laboratory for the Commission as part of the NRC's fire protection research program.
If the Board of the parties wish any additiona information, please let us know, i
Sincerely ,
,9 /
l q Joseph R. Gray l l Counsel for NRC Staff
Enclosure:
As stated cc w/ enclosure:
- Lawrence Sager, Esq. Theodore A. Adler, Esq.
Dr. Chauncey R. Kepford Edward F. Lawson, Esq.
Eugene J. Bradley, Esq. Susquehanna River Basin Commission Dr. A . Dixon Callihan Atomic Safety and Licensing Donald P. Irwin, Esq. Board Panel 3.
Michael W, Maupin, Esq. Atomic Safety and Licensing ,
George C. Freeman, Jr. , Esq. Appeal Panel I W. Jeffrey Sidebottom, Esq. Docketing and Service Section Gilbert G. Malone, Esq.
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8 UNITED STAT C E
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i k...../ September 29, 1978
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- l MEMORAftDUM FOR: Chairman Hendrie l Commissioner Gilinsky Commissioner Kennedy i Commissioner Bradford
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Commissioner Ahearne ,-.
THRU: txecutive' Director for Operations h FROM: Harold R. Denton, Director Office of fluclear Reactor Regulation
SUBJECT:
NRC FIRE PROTECTION RESEARCH TEST M
On September 15, 1978, a fire test of a full-scale vertical cable tray array was conducted at the Underwriters', Laboratory near Chicago, Illinois. It was part of the NRC-expedited fire protection research program requested in the Commission's Orcer of April 13, 1978. The purpose of the test was to demonstrate the effectiveness of area sprinklers and mincral wool blanket type cable tray fire barriers in preventing damage to cables as a result of an exposure fire created by igniting two gallons of heptane.
The configuration of cables and fire protection features in the test did not simulate any particular nuclear i ower plant. There are plants in operation and under construction for which the electrical cable tray configuration of the test was typical. However, based on the staff's ongoing fire protection reviews, we know of no operating '
plants with the configuration of fire protection features used in l the test, although features of this type have been proposed for l installation and are currently under review by the staff. (
l The test resulted in damage tc some of the electrical cables. Prelim-inary analysis (see Enclosure 1) indicates that the configuration of fire protection features used in the test would not be acceptable for application in nuclear power plants. In particular, it appears that fire barriers for vertical trays in some configurations may need to be designed to prevent entry of flanmable fluids. A wick effect may also need to be considered in the design of fire Sarriers. The response of the fusible link sprinklers used in the test is also under further study.
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The Commissioners fj e
Tue test results are still being analyzed and it would be premature to establish firm conclusions at this time; however, the results now
- available suggest that modifications to certain of the staff's fire protection criteria may be necessary. The staff is continuing its review and will meet with the test ccatractors (Sandia and UL) on ;
October 3,1978'to further study the prelirrinary findings and results. A quick look report is expected d o be completed by UL within the next several days and will be issued by Sandia shortly thereafter. The schedule and nature of further testing under this program are under review. -
We will keep the Commission informed of significant results and ,
possible . impacts on operating reactors as information becomes available.
A circular or bulletin will be issued by IE to inform licensees of the results of the test. Its preparation will follow the October 3 -
meeting with the contractors. Plants currently in operation remain subject to administrative procedures aimed at minimizing the sources of ignition and continue to maintain manual fire f-ighting capability.
We will. inform the Commission of any action deemed necessary as a result of our continuing review of the test results. The public announcement provided in Enclosure 2 is planned for release by the Office of Public Affairs on October 2. We are in the process of informing the ACRS'and Hearing Boards where this information is relevant.
/ 4&S Harold R. Denton, Director Office of Nuclear Reactor Regulation l
Enclosures:
- 1. Preliminary Analyses
- 2. Public Announcement cc: (w/encls.) -
Union of Concerned Scientists )
Office of the Secretary h?.C Public Document Room 1
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- SEP 2 71978, u
MEMORANDUM FOR: Robert L. Tedesco, Assistant Director
. for Plant Systems ,
Division of Systems Safety FROM: Gregory A. Harrison Auxiliary Systems Branch Division of Systems Safety
' Philip R. Matthews, Section Leader Auxiliary Systems Branch .
Division of Systems Safety i l
THRU: Victor Benaroya, Chief l Auxiliary Systems Branch
. Division of Systems Safety
SUBJECT:
UL FIRE PROTECTION TESTS On' September 15, 1978, Underwriters Laboratory conducted a full scale I vertical cable tray fire test including fire barriers and sprinklers. '
The source of the fire was two gallons of heptane liquid. This test was part of the expedited fire protection research program as requested in the Commission's order of April 13, 1978. The purpose of the test was to demonstrate the effectiveness of area sprinklers and cable tray fire barriers in preventing damage of safety significa- 'Se cable circuits due to exposure fire conditions.
The configuration of the fire test was selected to simulate a section l of a plant area with wrtical cable trays containing redundant safety i divisions arranged such that the redundant divisions could be simul- l taneously exposed to a potential fire resulting from an inadvertent .
l spill of flanmable liquid in the area. The arrangement of the cable 1 trays and the designation of the redundant tray divisions is shown in Figure 1 taken from the User Request Memorandum.1/ Figure 2 shows the location of the fire detectors and the three groups of sprinklers.
Each of the five cable trays was enclosed in a separate mineral wool blanket fire barrier from floor to ceiling in accordance with the manu-facturers specifications currently recommended to their customers.
The sprinker and detector arrangement was as permitted by NFPA Code.
1/ . %/$$5G373 User Request Memorandum dated June 1, 1978, from E.G. Case, NRR to S. Levine, PES ,
Enclosure 1 hM 4j l
h Robert L. Tedesco p
SEP 2 71978 u
I Each sprinkler location contained three nominally identical tempera-ture 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
'j fused. After all three temperature sensing heads at a given location 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 A detailed description in the response time of identical sprinklers.
of the test set up and procedure will be in the UL test report which will be issued later. It was agreed that the demonstration would be !
considered to have no safety significance if the electrical circuits '
did not fail in more than one tray.2/
The following suimiary of the test results is based on direct observa- ;
tion of the test by NRC staff. Test data are still being correlated '
by UL and will be included in their Quick Look Report to be issued to Sandia for its review shortly.
The test was started by igniting the two gallons of heptane that was poured inta the floor pan. A fully developed fire occurred almost inrnediately. 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 mineral 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 tio additional temperature sensing surface of the mineral blanket. -
sprinkler heads at any location activated; thus, the sprinkler water supply wa< not turned on for any of the three sprinkler loca-The apparent tions. tio water was used at any time during the test.
slow response of the third temperature sensing sprinkler is being investigated. ,
1 1
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U emorandum M dated September 13, 1978, from V. Benaroya and G. Lainas to G. Bennett
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At about 3 minutes there was an indication of a short circuit in cable trays 3, and after 7 minutes indication of a short in tray 1.
After 5-7 minutes the height of the flames appeared to subside; however, residual flames continued for about 40 rninutes. It was reported that apparently the highest measured temperature inside any cable bundle was less than 150 F; however, damage to the cables' indicates that higher temperatures were reached in the trays at the bottom regions, below the location of the thennocouples.
Test results are still being analyzed and no firm conclusions can be drawn at this time. Preliminary information received from RES subse-quent to the test indicates that the flan:nable liquid or flames pene- ~
trated an opening in the protective barriers at the bottom of the vertical trays and caused fire damage to the PVC cables in four of ,
the five trays. The electrical short to ground that occurred in cable tray 3 probably was caused by the fire. The second electrical
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short in tray l apparently was caused by a broken instrument connec-tion, and is not considered to be related directly to the fire. On subsequent 500-volt rnegger tests, it was found that another cable in tray 2 had also experienced some damage.
The most probabic cause of the fire damage in certain cable trays appears to be related to the absorption and/or seepage of heptane under the mineral wool 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. It is believed that this type of failure mode could be prevented by using a seal material that would prevent the absorption or the seepage of heptane under the I mineral wool blanket. There is some indication that some ccble damage I was caused by absorption of the inside of the barrier (wicking effect) which heated a cable tray ladder, causing damage to a cable in contact with the ring. The investigation of the results is still underway, and while no definitive findings can be stated, damage did occur to cables in several trays due to the fire. The slow response of the sprinkler system was not predicted. The ingress of the heptane into the mineral wool needs to be further evaluated since this appears to be the most significant failure mode.
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: (a) fire detectors located approximately 15 feet away from the fire promptly (N15 seo) detected the fire; (b) some small fires may not actuate sprinkler heads; and (c) protective barriers should be designed to prevent the entry of flarrrnable liquids.
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Robert L. Tedesco 4 SEP 2 7 g The staff plans to meet with personnel from Sandia .and LL during the first week of October. A Quick Look Test Report is expected to be released in early October.
It does appear that further evaluation of the results may lead to the formulation of supplemental fire protection requirements concerning seals and types of sprinkler heads to be used. In view of this, it is appropriate to notify the ACRS, the Commission, and any Boards, where this issue is relevant, as 'to the current situation. We will continue our evaluation of the test results and consideration of new additional tests to be conducted. A Office of Public Affairs (public announcement Enclosure 3) and ' has been to be prepared released by the September 29, 1978. ,
5
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PUBLIC AtlN00flCEl<EllT l NRC Staff Evaluating Results of Test of Fire Protection Systems -
The staff of the fluclear Regulatory Commission (flRC) is evaluating the results of a recent test of fire suppression systems to determine whether changes should be made in NRC fire protection criteria for nuclear power plants.
As part of NRC's research program, the test was conducted at -
Underwriters.' , Laboratory (UL) near Chicago on September 15, 1978.
The test involved electrical cables in five vertical trays and included fire barriers and water sprinklers. The test resulted in damage to some of the electrical cables. Preliminary analyses indicate that the fire barrier and sprinkler configuration used in the test would not by itself be acceptable fire protection in nuclear power plants.
As a result of the fire at the Browns Ferry Nuclear Plant in Alabama in 1975, the NRC has imposed strict administrative controls over fire ignition sources at all nuclear power plants, and manual firefighting capability has been strengthened. Fire suppression systems of the type tested at Underwriters' Laboratory are among those being reviewed for further strengthening of fire protection in these plants. Although some pignts already have sprinkler systems, ,
and many rely on various types of fire barriers, the NRC staff knows of no present use of the system tested at Underwriters.' Laboratory.
Enclosure 2 u -
_ _ _ _ _ _ __ s