ML20032B786
| ML20032B786 | |
| Person / Time | |
|---|---|
| Site: | Point Beach  |
| Issue date: | 10/29/1981 |
| From: | Churchill B SHAW, PITTMAN, POTTS & TROWBRIDGE, WISCONSIN ELECTRIC POWER CO. |
| To: | |
| References | |
| NUDOCS 8111060318 | |
| Download: ML20032B786 (8) | |
Text
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11 EV -3 P3:M ITED STATES OF AMERICA
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NUCLEAR REGULATORY COMMISSION NOVO 51
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[0 eNO[e Atomic Safety and Licensing Board "'8g
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In the Matter of
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m WISCONSIN ELECTRIC POWER COMPANY
)
Docket Nos. 50-266
)
50-301 (Point Beach Nuclear Plant,
)
(OL Amendment)
Units 1 and 2)
)
LICENSEE'S SUPPLEMENTAL RESPONSE TO BOARD OUESTION ON DEPLUGGED TUBES Following is Licensee's supplemental re.tponse to Question 2 set out in the Board's October 13, 1981 " Memorandum and Order Concerning Further Board Questions," in accordance with the Board's request, memorialized at Tr. 133.
YUESTION 2 Please show in one table (or set of tables) all tests performed on, tubes from which plugs were removed and the results of those i
tests.
Minimum values and ranges should be indicated.
Tables i
should be clearly labeled so that they disclose differences i
between the testing conditions and the Point Beach project.
RESPONSE
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As noted in Licensee's response to Question 3 of the second round of Board questions, in excess of [
]a,c,e tests of specimens of plugged and deplugged tubes have been performed, to study the intagrity of the tube-to-tubesheet weld. The results of those test are described generally in Licensee's response to Question 3 of the second round of Board questions; as discussed there, in some of those laboratory test
~8111060318 811029 p$d8 PDR ADOCK 05000266 G
PDR 9
specimens, the tube-to-tubesheet welds were non-destructively tested prior to plugging and after plug removal, and exhibited no weld cracking.
In a recent, more definitive set of. tests, the removal
' of mechanical plugs from plugged tubes and the effects on tube-to-tubesheet welds were tested under conditions more severe than are expected to be encountered in the fie.ld.
Non-destructive examination of the tube-to-tubesheet welds after plug removal showed no signs of weld degradation due to plug removal.
Data regarding these recent tests are provided in Table 1.
These tests are conservative for the following
~
reasons:
1.
Test specimens used tubes which were rolled into the simulated tubesheet for a distance of only 7/8-inch
. compared to the approximately 2-inch' roll used in actual steam generators.
The shorter roll results in higher pulling forces transmitted to the tube-to-tubesheet weld during plug removal than would be encountered in the field.
2.
The tube-to-tubesheet weld in the test specimehs was machined to obtain the minimum acceptable tube-to-tubesheet weld.
This results in higher weld stresses than would be encountered in the field.
3.
The plugs were installed in the test specimens at forces greater than the field installation force of 17,000 lbs..This results in abnormally high plug removal forces.
Further, additional information about the effects of the removal-of mechanical plugs on the interior surface of tubes has been culled from the visual inspection of approxi-mately 70' tubes involved in the two groups-of tests described above. The results of those inspections, generally of a quali-tative nature, do not lend themselves to tabular presentation, but are summarized below:
1.
Mechanical plugs can be consistently removed from tubes after they have been installed.
2.
Occasionally, a plug may break during the removal operation and the broken portion of the plug which remains in the tube can be removed from the tube by machining methods.
3.
The tube interior surface may receive from only very slight to moderate damage during the removal operation, all of which may or may not require repair by machining methods.
In the case of only very slight damage, a mechanical plug may be installed with no repair of the tube surface.
4.
Most of the damage during nearly all of the plug removals occurred to the mechanical plug -- not'to the tube surface.
5.
In all cases, the tube-to-tubesheet weld was not damaged.
4 i
Additional tests.have been conducted on explosive plug removal.
These tests were conducted in the qualification of the equipment for explosive plug removal and also to provide l i
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specimens for mechanical testing as outlined in the Sleeving Report on pages 6.8 and 6.9.
Eight specimens were included in the mechanical tests. The results are shown in Table 2.
In addition, ten samples were prepared for equipment qualification.
The results of the tube inspection for these ten specimens is also shown in Table 2.
In order to establish a visual reference for tube conditions in the field, photographs were made of machined surfaces and will be used in the field as an aid to determine acceptable or rejectable conditions along with the diameter measurements that will be taken.
Tubes that are found to be unacceptable for sleeving will be plugged.
The difference between the test specimens and field conditions is that the plugs in the field have been exposed to the steam generator operating conditions.
This difference is not expected to introduce new problems'for either the mechanical plug or the explosive plug removal.
Respectfully submitted, SHAW, PITTMAN, POTTS & TROWBRIDGE' s
i By:
t 3ruce W.Mhurchill Delissa A. Ridgway Counsel for Licensee 1800 M Street, N.W.
Washington, D.
C.
20036 (202) 822-1000 Dated:
October 29, 1981
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1 TABLE 1 4
MECilANICAL PLUG REMOVAL TESTS Mech.
Plug Installation Parameters Removal Parameters Serial larce Dist.
Pressure 1st Pull 2nd Pull 3rd Pull 4th Pull Sth Pull
_6th Pull 1
(Lbs.)
(Inch)
( Psici)
Psig Lbs.
Psig Lbs.
Psig Lbs.
Psig Lbs.
Psig Lbs.
Psig Lbs.
i l
1294 17,840 0.867 6,440 2,300 6,340 j
1281 17,820 0.864 6,440 4,000 11,040 4,500 12,420 5,000.13,820 5,500 15,180 5,700 15,732 j
1245 17,830 0.861 6,440 4,000 11,040 4,500 12,420 4,700 12,972 4
1205 17,870 0.872 6,450 4,000 11,040 4,500 12,420 4,600.
12,696 i
1227 17,870 0.850 6,450 4,000 11,040 4,500 12,420 4,900 13,524 1206 17,820 0.859 6,450 4,000 11,040 4,500 12,420 4,800 13,248 1250 17,820 0.879 6,440 4,000 il,040 4,300 11,868
.i 1222 17,830 0.846 6,440 4,000 11,040 4,500 12,420 5,000 13,800 5,500 15,180 6,000 16,560 6,100 16,236 1
]
1241 17,630 0.861 6,440 4,000 11,040 4,500 12,420 4,700 12,972 l
1240 17,830 0.848 6,460 4,000 11,040 4,500 12,420 4,600 12,646
\\
- The area of the cylinder employed was 2.76 in2 The removal forces were calculated b'y multiplying the recorded.
pressure by this area.
l 4
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TABLE 2 EXPLOSIVE PLUG REMOVAL TESTS ID OF TEST REAMER TUBE AFTER NO.
SIZE REAMING CONDITION OF TUBE SURFACE 1
0 008 0.810 to 0.813
/
2 0.808 0.811 to 0.812 Surface conditions were found 3
0.808 0.810 to 0.812 to have light circumferential 4
0.808 0.811 to 0.812 reaming marks.
All samples 61 0.797 0.799 to 0.801 would be acceptable for 76 0.806 0.809 sleeving.
Reamer size for 81-0.806 0.807 to' O.808 field conditions has been 99 0.806 0.807 to 0.808 set at 0.806 to minimize 408 0.806 0.808 to 0.810 tube wall removal and provide 457 0.806' O.807 to 0.808 maximum surface reaming.
MECIIANICAL TEST SPECIMENS 28 0.797 0.800 Surface conditions wer'e found 37 0.804 0.806 to have light circumferential 46 0.797 0.799 to 0.800 reaming marks, acceptable 89 0.806 0.810 for sleeving.
Test sleeves 93 0.812 0.814 installed and tested per 115 0.797 0.799 to 0.800 item 6 of Table 6.1-3 of the Sleeving Repon
- 155 0.006 0.809 Unacceptable - sleeved and tested
- 191 0.806 0.806 to 0.808 Unacceptable sleeved and tested
- Both tes t samples leaked on test.
UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMISSION Before the Atomic Safety and Licensing Board In the Matter of
)
)
WISCONSIN ELECTRIC POWER COMPANY ) Docket Nos. 50-266
)
50-301 (Point Beach Nuclear Plant,
) (OL Amendment)
Units 1 and 2)
)
CERTIFICATE OF SERVICE This is to certify that copies of Licensee's Supplemental Response To Board Question on Deplugged Tubes" were served, by hand,on all those on the attached service list, on October 29, 1981, except that those whose names are marked by an asterisk are being served with a non-proprietary version of the document, by deposit in the U.S.
Mail, first class, postage prepaid, this 2nd day of November, 19 1.
. d uns
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V Deli'g A.)RidjJway Dated:
November 2, 1981
UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMISSION Before the Atomic Safety and Licensing Board In the Matter of
)
)
l WISCONSIN ELECTRIC POWER COMPANY ) Docket Nos. 50-266 l
)
50-301 (Point Beach Nuclear Plant,
) (OL Amendment) l Units 1 and 2)
)
SERVICE LIST Peter B.
Bloch, Chairman Charles A.
Barth, Esquire Atomic Safety and Licensing Office of the Executive Board Panel Legal Director U.S. Nuclear Regulatory U.S.
Nuclear Regulatory Commission Commission Washington, D.C.
20555 Washington, D.C.
20555 Dr. Hugh C. Paxton Kathleen M. Falk, Esquire 1229 -41st Street Wisconsin's Environmental Los Alamos, New Mexico 87544 Decade 114 North Carroll Street Dr. Jerry R. Kline Suite 208 Atomic Safety and Licensing Madison, Wisconsin 53703 Board Panel U.S. Nuclear Regulatory Commission Washington, D.C.
20555
- Atomic Safety and Licensing Board Panel U.S. Nuclear Regulatory Commission
' Washington, D.C.
'20555
- Atomic Safety and Licensing Appeal Board Panel U.S. Nuclear Regulatory Commission Washington, D.C.
20555
- Docketing and Service Section Office of the Secretary,
U.S. Nuclear Regulatory Commission Washington, D.C.
20555
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