ML20236Q187
| ML20236Q187 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 10/13/1987 |
| From: | William Jones, Ragsdale J, Wormsley J TENNESSEE VALLEY AUTHORITY |
| To: | |
| Shared Package | |
| ML20236Q176 | List: |
| References | |
| NUDOCS 8711190230 | |
| Download: ML20236Q187 (9) | |
Text
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ELEVATED TEMPERATURE TEST REPORT AND MECHANICAL PULL TEST REPORT FOR j
LITTELFUSE PLAS 5, 5 AMP FUSES l
LOT NOS. 002, 003, 004, and 006 l
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w mv weervaNugNEplwDg?SC3-C St5 697 4264 P.04 FORWARD This intermediate report is being lesued at the request of the Division of Nuclear Engineering (DNE) for documentation 'of tests performed on Littelfuse fuses Lot Nos. 002, 003. 00a. and 006.
Tests on tot Nos. 00s and 006 are continuing.along with tests on later manufacturer's lots.
Several sections of this report will also pertain to tests on these other lots.
PURPOSE Fuses manuf actured by Littelfuse as Let 'No. 003 have exhibited a high failure rate at Sequoyah Nuclear plant.
These tests were conducted to determine. if.
the replacements manufactured as Lot No. 006 are of better quality, and if possible, to determine when the fuses in tot No. 006 will begin to fall.
Lot No. 004 and future production lots may also be tested.
SCOPE Fuse samples were received from the plant for testing'in several conditions; used and still intact, used and f ailed, or as a test sample from a'new production lot.
Initial work consisted of preliminary examination of two failed fuses from Let No. 003, all other work was performed on fuses that. wore intact when received.
Tests to destruction by r.iechanical loading, application of current for long periods of time, and elevated temperature were used to evaluate the fuses.
TECTS Scanning electron microscope photos of failed and intact fuses provided a preliminary method of failure and possibly some clue' as to how to test the remainder of the fuses.
Sectioned samples were made to attempt to examine the internal porosity and bending of the~ soldered joint.
Tests were set up to pass a nominal current of two amperes through approximately one half of the sample and four amperes through the other half.
The time ~ until the first f ailure was asasured for each half of the sample.
The current was reapplied to the sample, the time until the next f ailure recorded, and the resulting total number of days service for each sample lot wee reported weekly.
Several of each lot were reserved for tests regarding mechanical load. bearing capabilities and it" possible to determine the relation between mechanical strength and failure rate.
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TEST SPECIMEN IDENTIFICATION I
Specimens were identified by Lot No. and individual fuse according to the type test to be performed.
Fuses that were to be mechanically loaded to f ailure were designated " Lot No. 00K 5".
The individual fuse number (example: Lot No.001, D.)
indicates the third fuse in Lot No.
6 that was pulled to destruction.
The letter in the fuse which the individual fuse was subjected as described below. identifier refers to th
- P" = pull tests "M"
elevated temperature "L" = two Ampere current "H". four Ampere current PP00EDUPE 1
I Scanning electron microscope photos of the fuses and mechanical tests of the strengths of the solder joints and the indicator pin actuating spring were used to provide a preliminary cause of f ailure and to identify other needed tests.
Fuso holders were obtained and the fuses fitted into them in a series arrangement for long-term current tests.
power supplies and loads were
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configured to obtain the nomine' test currents of' two and four' amperes.for i
sach test.
A shunt of approxi.
aly the same resistance as a fuse was placed i
in series with each group.
A out monitored the current by sampling the voltage drop across the shunt. acquis lessor provided a printout every 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />, a printout if the current dropped The data b' low 0.8 e
amperes (indicating a blown fuse), a printout if the current went above 5 amperes (fuse current limit), and a printout on demand.
In the event of a power failure the time will be printed in red until the correct time is resst.
These records show interruptions to the test and allow proper i
accumulation of the total test time.
REPORTS Daily reports to the plant on an informal basis-were.made during the preliminary t%sts.
Weekly progress reports on long-term tests will be sent to the plant.
Intermediate reports will be provided as report issued at the conclusion of the long-term current tests. requested and a final TEST EDUIPMENT. y,
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Digital Thermometer, Flute Model 216SA, US TVA No. 462383, with type K thermocouple, US TVA No. 903320.
Liquid in Glass Thermometer, US TVA 903322.
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i Data Acquisition System. US TVA No. 903250.
Precision Resistors, US TVA No. 903309, US TVA No. 903310. US 7VA No. 90 US TVA 903312. US 77A 903319.
TEST DESCRIPTION Long term current tests, as described in the procedure, were started for Lo*
No. 006 on July 10, 1987, for Let No. 003 on July 21, 1987, and tot No. 004 or August 11, 1987.
Scannin5 electron microscope photos and a meterials analysis of the selder in the fuse were reviewed by Ken Greene of DNE at the Central Laboratories Services Branch (CLSB).
These examinations and information provided by the manufacturer indicated that the element Bismuth was included in the used in Lot No. 003. Fuses from Lot No. 006 did not indicate a presence of Bismuth.
Four fuses from each of Lot No. 003 and 006 were placed in an oven, under no electrical load at 200 degrees Parenheit on July 29, 1987 to point, was a cause of the failure of Lot No. determine if the pres 003 fuses.
programmed to print the time when each fuse failed due to this temperature.The dat l
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PESULTS The photographs taken at the CLSB indicated partial moltir.g was present in a of the failed fuses; however, there was also present a larse amount of porosity in the solder, a great variability in the wettin$ of ths cemponents by the solder inside the fusos, and even one fuse with almost no solder.
These These problems also influenced to some extentproblems were v4wed The pull tests were made on tot No.
the pull tests that were made.
002, 003, and 004 fuses and indicated that the solder joint was stronger than the resistor body to which it was attached.
The Lot No. 002 and 003 fuses pulled apart at approximately 10 pounds less than Lot No. 004 The pull test results are attached as Appendix 1.
i h covits of tne elevated temperature tests provided a more pronounced difference.
The first fuse from tot No. 003 failed within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />. The second and third fuses failed between 24 and 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> and the failed prior to 80 hours9.259259e-4 days <br />0.0222 hours <br />1.322751e-4 weeks <br />3.044e-5 months <br /> into the test.
The first fuse _ from Lot No. 006' failed on September second fuse failed *on day AS, the third on day $1, and there re from Lot No. 006 that has not failed at present (71 days).
one fuse Additional tests on tot No. 00s, 006 and later manufactured. lots to measure the effects of temperature rise with various currents were reported to DNE o October 1, 1987 (alms No. E13 871001 167 ), but these results did not include n
results for Lot No. 003.
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a m eruu4:En it& %P5C3-C EIS 697 4364 P.37 The Isng-tera curr;nt tests on Lot No.
003 were discontinued af ter 40. days.
The fuses in the higher. current loop (which produced higher solder - joint temperatures in all Lot Nos.) f ailed at a much higher rate than Let Nos and 006. Eleven of the fuses in the four ampere circuit f ailed within 33 004 days.
The first fuse in this circuit failed on day five of the test.
two ampere circult only one fuse failed (at day 26) during a total of 40 In the days.
No fuse has, at this time, failed in the long-term current tests other than those in Lot No. 003.
The photographs, data logger records, and failed fuses that were not de during the tests are 'being held at the current tests on all other fuse lots and will be included in the final r as appropriate.
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APPENDIX I
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FUSE IDENTIFIER SPRING TENSION PAILURE LOAD REMA RKS (1bs)
(1bs)
LOT 002 P1 1.15 29.25 resistor body failed P2 1.12 5.25(pin).
spring unwound at 15.25 lbs P3 1.13 5.25(pin) spring unwound at 15.25 lbs
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i LOT 003 P1 1.23 5.25(pin) spring' unwound at 15.2$_Ibs P2 1.13 23.25 resistor body fallec.
P3 1.12 18.25 resistor body failed PA 1.14 22.25 resistor body failed PS 1.13 19.25 resistor body failed j
P6 1.12 5.25(pin) spritig unwound at 11.25 lbs J
P7 1.10 19.25 resistor body failed p8 1.12 22.25 reslutor-body failed i
P9 1.15 22.25 resistor body failed P10 1.13 24.25 resistor body failed-i P11 1.18 5.25(pin) spring unwound at 13.25 lbs P12 1.13 17.25 resistor body failed F13 1.13 10.25(pin) spring unwound at 11.25 lbs P14 1.03 5.25(pin) spring unvound at 11'.25 lbs P15 1.08 13.25(pin) spring unwound at 16.25 lbs P16 1.20 20.25 resistor body failed
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P17 1.20 5.25(pin) spring unwound at 13.25 lbs l
PIB 1.13 5.25(pin) spring unwound at 12.25 lbs l
P19 1.09 13.25 resistor body failed P20 1.24 25.25 joint Iailed 1.
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LOT 004 P1 1.02 31.25 resistor body falled I
P2 1.06 29.25 resistor body failed P 3.
0.91 33.25 resistor body failed P4 0.80 34.25 spring-resistor joint failed P 5..
1.02 28.25 resistor body failed P6 1.07 35.25 resistor body failed P7 1.18 20.25(pin) spring unwound et 18.25 lba
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P8 1.15 30.25 resistor body failed P9 1.13 20.25(fatigue) weight applied overnight P10
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1.15 30.25 resistor body failed '
P11 1.12 33.2[
_ resistor body fa}1ed 5
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32/;2/1997 14:49 C&EfVEN3]NEERING/DBS503-C 6:5 697 4:54 5.09 APPENDU ((
est Available Copy FUSE IDENTIFIER STARI DAT8 STOP DATE TOTAL TIME Lot No.003 L1 7-21-87 6-31-87*
40 days L2 7-21-87 6 31-87*
40 days L3 7-21-87 8-31-87*
40 days LA 7-21-87 6-16-87 26 days LS 7-21-87 6-31-87*
i 40 days L6 7-21-87 6-31-875 40 days L7 7-21-87 6-31-875 40 days LB 7-21-87 8-31-87*
40 days i
L9 7-71-87 6-31-87*
40 days L10 7-21-87
.8-31-87*
40 days L12 7-21-87 6-31-87*
40 days L12 7-21-87 8-31-875 L13 7-21-87 40 days 6-31 87*
40 days L14 7-21-87 6-31 87*
40 days LIS 7-21-87 6-31-87*
40 days i
L16 7 21-87 6-31 87*
40 days L17 7-21-87 6-31-87*
L18 7-21-87 B-31-875 40 days L19 7-21-87 40 days L20 8-31-87*
- 40. days 7-21,87 6-31-E7' 40 days FilSE IDENTIFI!_R START DATE STOP DATE TOTAL TIME kot No.003 H1 7-21-87 8-5-87 H2 7-21-87 7-30-87 15 days H3 7-21-87 8-31-875 9 days H4 7-21-87 7-28-87 40 days HS 7-21-87 7 days N6 7-28-87 7 days 7-21-87 6-31-87*
. H7 7-21-87 B-31-87*
40 days HB 7-21-87 7-26-87 40 days H9 7-21-87 8-13-87 5 days H10 7-21-87 6-31-875 23 days H11 7-21-87 8-31-875 40 days E12 7-21-87 40 days HIS 8-11-87 21 days H14 7-21-87 8-31-87*
40 days 7-21-87 H1$ %
8-7-87 3
"17 days V
H16 7-21-87 6-3$-87*
40 days
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7-21-87 8-6-87 16 days Hi?
7-21-87 8-31-87*
40 days H18 7-21-87 B-19-87 29 days H19 7-21-87 H2O 6-31-875 40 days 1
7-21-87 8-4-87 14 days
- Lot No. 003 removed from test by instruction from DNE on 8-31-87.
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1 "Sequoyah Nuclear Plant j
Littlefuse Type FLAS-05 Fuses Predicted Service Life SME-MET-87-901" i
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c4y B43 77 C 92 8 001-
- DNITt:D BTATES GOVERNMENT Memorandum TENNESSEE VALLEY AUTHORITY I
To W. S. Raughley, Chief Electrical Engineer, W8 0126 C-K ynom D. W. Wilsort, Chief Nuclear Engineer, W10 C126 C-K Hest Available Lopy
,SEP 281987 utTE l
SEQUOYAH NUCLEAR PLANT - LITTLETUSE TYPE FLAS-05 FUSES -
st:10ECT:
LIFE We are transmitting the Singleton Materials Engine.ering Laboratory report SHE-MET-87-901 as requested by Ken Green on August i
18, 1987.
Please refer i
to a preliminary report on FLAS-05 fuses given as QIE NEB 87281 (B46 870919 I
003).
OU Und y D. W. Wilson (p,PVG:MHD p Attaohnents N.
oo (Attachments): \\
...EINS._SL26 C-K t
s W. H. Childres, SME-K j
l This was prepared principally by Paul V. Outhrie Jr., extension 2771..
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