ML19208A401
| ML19208A401 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 08/06/1979 |
| From: | Reid R Office of Nuclear Reactor Regulation |
| To: | Herbein J METROPOLITAN EDISON CO. |
| References | |
| NUDOCS 7909130524 | |
| Download: ML19208A401 (5) | |
Text
.
/
'o UNITED STATES
[
[;* /g
! ]
s., ( ~ gg NUCLEAR REGULATORY COMMISSION
'7 WASHINGTON, D. C. 20555 4g /7fp
. y[g August 6, 1979 N
Docket No. 50-289 Mr. J. G. Herbein Vice President Metropolitan Edison Company P. O. Box 542 Reauing, Pennsylvania 19640
Dear Mr. Herbein:
. The Three Mile Island Unit No.1 (TMI-1) Fire Protection Safety Evaluation Report (FPSER) under Item 3.2.2, Cable Separation, specified that a study and/or testing be performed cn the asbestos board fire barriers which protect TMI-l cable trays and conduits. The purpose of this study and/or testing is to verify the effectiveness of the presently installed design in pre-venting the spread of a cable tray fire to other trays and in preventing damage to redundant cables in the event of an exposure fire.
By letter dated May 18,1979 (GQL 0692) you provided a description of the proposed test to be perfomed as part of this verification program. This submittal which was provided to us for irdomation and comments, includes the design of the test cable trays, description of asbestos board and test procedures for two tests.
We have reviewed your submittal and discussed our coments with your staff by telephone. These comments are listed in the enclosure and confirm our understancing of the resolution.
In regard to applying the test results, the submittal does not state the specific objectives nor the criteria to judge the results for acceptability. We expect these items to be covered in the final report.
The submittal shows that you are planning two tests, one tray fire test and one exposure fire test on the same tray and conduit configuration. The test results would be applied to evaluate other configurations that exist throughout the plant.
In selecting those plant configurations that would be bounded by test configuration, we should be assured that each test variable reflects the most conservative condition existing in the plant configurations. Although these tests will verify the effectiveness of the asbestos for the board barrier design as called for in Section 3.2.2 of the FPSER, other lines of defense, such as
- 34. 2 6 7009130S y p
Mr. J. G. Herbein detection and suppression, will still be required as appropriate for the individual configuration and potential consequences.
For an example, in those areas where a large concentration of cables exist, a fixed suppression system will be required in addition to an adequate cable separation.
Sincerely, Robert W. Reid, Chief Operating Reactors Branch #4 Division of Operating Reactors
Enclosure:
FPSER Comments cc w/ enclosure:
See next page
,I.
iletropolitan Edison Company cc:
G. F. Trowbridge, Esquire Shaw, Pittman, Potts & Trowbridge 1800 f1 Street, N.W.
Washington, D.C.
20036 GPU Service Corporation Richard W. Heward, Project Manager Mr. E. G. Wallace, Licensing Manager 260 Cherry Hill Road Parsippany, tiew Jersey 07054 Pennsylvania Electric Company Mr. R. W. Conrad Vice President, Generation 1001 Broad Street Johnstown, Pennsylvania 15907 Miss Mary V. Southard, Chairman Citizens for a Safe Environment P. G. Box 405 Harrisburg, Pennsylvania 17108 Mr. Robert B. 3orsum Babcock & Wilcox Nuclear Power Generation Division Suite 420, 7735 Old Georgetown Road Bethesda, Maryland 20014 Government Publications Section State Library of Pennsylvania Box 1601 (Education Building)
Harrisburg, Pennsylvania 17126 t
e wc O
~
~
o JU
_ A 1) a w1:ai$
Enclosure TMI-l FIRE PROTECTION SAFETY EVALUATION REPORT COMMENTS The following are comments on the proposed test to determine the adequacy of the fire barriers existing at TMI-1:
1.
Size of the Excosure Fire Because the configuration of the test simulates an area that is free of fixed combustibles, the amount of transient combustibles that can be brought into or through the area under consideration should be factored into the deter-mination. To demonstrate that the barrier provides protection from an exposure fire, the fire should represent a significant threat to the cables and challenge to the barrier. The test should include a reproducible arrange-ment so that if further tests are performed the results can be compared easily.
The licensee proposed and we agreed that the size of the test fire will be based on the transient combustibles permitted by the licensee's administrative procedures which will also include an allowance for a breakdown of these procedures.
2.
Size of the Cable Tray Fire The oil soaked burlaps may not produce enough heat to develop a well-developed cable tray fire.
We prefer the use of propane, heptane, or methane burners to assure a well-developed tray fire challenges the fire barrier.
The licensee agreed to usetwo 70,000 STU/hr methane burners and cause ignition in the cable tray that would res' ult in~a well-developed fire.
3.
Trav and Conduit Conficuration The proposed test configuration of trays and conduits does not appear to envelop all configurations of concern. The licensee was requested to compare the test configuration with those of various plant areas to which the test results will be applied. Variables to be verified include tray stacking above and below the barrier, relative distances of test components with respect to one another and to the floor and the ceiling, mixtures of IEEE 383 and (if existing) non-383 cable, and mixtures of power and. control cables.
The licensee agreed to identify the plant areas for which the selected test configuration is applicable in the test report.
250 94.Jin&'
4.
Enercizinu Test Circuits The procedures call"for energizing cables in trays E and C and in the conduits to 120 volts; however, they are energized in such a way that currents are limited as insulation' degradation occurs. The concern is that as the cable insulation is degraded during a cable fire, the leakage current will provide another heat source that should be considered in the fire test. The cable current during the test should be representative of the insitu plant conditions.
The licensee has proposed and we have agreed that the conductors during the test fire will be energized to the wire rated current at 120V AC. The circuit sill contain a 15 amp fuse, a current measuring device and a lamp to indicate that power is applied to the circuit.
5.
Relative Location of Fire The proposed arrangement of locating the fire at the center of the barrier appears not to correspond to the worst case conditions. Thetestfire(s) should be initiated at approximately halfway between the center and the edge of the barrier or at the edge of the barrier to present the most severe
' challenge to the barrier's ability to protect the higher tray from an exposure fire that may affect the lower tray.
The licensee agreed to relocate the fire at the location which presents the most severe challenge to the barrier. The centerline of the exposure fire will be halfway between the edge of tray A and the edge of the barrier along the centerline of tray E.
LM b'JGO 251