ML19329E886
| ML19329E886 | |
| Person / Time | |
|---|---|
| Site: | Midland |
| Issue date: | 04/22/1977 |
| From: | Howell S CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | Hayes D NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| References | |
| HOWE-70-77, NUDOCS 8006180720 | |
| Download: ML19329E886 (6) | |
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- 3T JO -3.56 ej'j Stephen H. Howell J
Is Vice President
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Generof Offices: 1945 West Pernell Roed.Jeckson. Michigan 49201
- Aree Code 517 788-0453 April 22, 1977 Howe 70-77 Mr D W Hayes Senior Reactor Project Inspector Office of Inspection & Enforce =ent Region III
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.US Nuclear Regulatory Co= mission 199 Roosevelt Road Glen Ellyn, IL 60137 During your April 14, 1977 visit to the Bechtel - Ann Arbor offices, you requested copies of certain documents which provide plans to evaluate the extent of damage relating to the bulging of the Unit No 2 containment liner plate. These documents could not be given to you because they are in a form which Bechtel policy requires be limited to internal Bechtel distribution. Bechtel has now provided the re-quested information in a documentary form which can be distributed externally and, therefore, a copy is herewith enclosed for your use.
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THIS DOCUMENT CONTAINS POOR QUALITY PAGES
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8006180 M O APR 2 51977
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Bechtel AsLciates Professional Corhoration
'777 East Eisenhower Parkway C
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Ann Arbor, Michigan h
u.r4eess.P.O Dox 1000, Ann Arbor, Micnigan 48100 I
l April 18, 1977 BLC-3948 Cmisumers Pouer Company 1945 W. Parnall Road Jackson, Michigan 49201 Attention:
Mr. R. C. Bauman
Subject:
Consumers Power Company Midland Plant - Job 7220 Damaged Liner Plate File: G270, 0670.1, C-2167 Gentlemen:
Pursuant to your request at the liner plate meeting with the NRC on 4/14/77, we have summarized Project Engineering's direction regarding investigation of the damaged containment liner plate between azimuths 2500 and 270 of Unit 2.
These direc-ions were forwarded to Bechtel construction earlier in four separate ecmos.
GENERAL:
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No repairs of the damaged arca and plate shall be started until k Project Engineering approval is received.
[y RECORDS:
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2.
The damaged plate shall be surveyed'to record the bulged profile.
A sketch showing the development of the plate shall be maintained to record the location of the preliminary holes, observations noted, and to identify the position of the designated removed plate segments for later study.
Photographs shall be taken as requested by Engineering.
Additional information was later requested after most of the liner plate was removed, including:
3.
In the damaged arca, show the existing condition with dimensions locating the embedded channels and the concrete markup of the stiffening ang1cs. Any angles which are still embedded in concrete should be identified (length and location) on a sketch.
Arcas
-where the flange of the W14X61 columns has deformed should be described. Tnc c:: tent to which the liner was cut at the top should be shown.
Arcas where concrete has been removed more than 3" in depth and areas where concretc is intact (e.g., near the penetration assembly at El. 605/009 and near the columns and high r clev.itions)
' should be identified.
c The channels which were pulled out from the kN
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Bechtel Associates ProfessionalCoiporation Consumers. Power Company BLC-3948
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Page 2 concretc should be marked up and the length and location of the por. ions which were pulled out should be given.
Information, other than uhat is listed above, describing the existing condition of the subject panci should be included.
4.
'On the same sketch tha penetration assembly at El. 605/609 and the embedment at El. 691 have been covered by a 4"x4" grid. The defor-mation within these areas should be measured at the nodal points of the grid.
In regions where the plate is not excessively deformed (as determined by the engineering representative), m2asurements can be taken-at alternate nodal points (8" spacing rather than 4").
' LINER PLATE REMOVAL:
Initial direction included:
5.
Remove t'he damaged 1/4" liner plate between azimuths 250 and 270 except as noted below:
Allow a'six inch minimum width of 1/4" liner plate to remain attached to the following items: 1) 14 HF strong backs at azimuth 250 and 2700, 2) the 1/2 inch thickened liner plate about the penetration, 3) the bottom of the liner plate shall not be initially cut below elevation 594'-0".
The plate shall not be removed above elevation 690' or where no further bulge is apparent ac determined by the engineering representative.
6.
Representative samples as selected by the structural engineering representatives shall be marked for later identification. This identification shall be noted on the developed elevation sketch.
Damaged plate sections shall be retained until Project Engincaring review is completed.
Construction has the option to cut the plate to sizes convenient for the handling.
7.'
Leak chase channels may be cut as required.
Precautions shall be taken to prevent foreign material from entering remaining channel.
8.
The wind girder at approximately clevation 670' may be removed.
Replacement is a field option inasmuch as the structural purposes of this~ member is now obsolete.
Later, the above direction was modified.as follows:
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-Cut the buckled panel of the liner plate approximately 1" from the edge of the embedded coltmin flange on cach side of a;:imuths 250 0
and 270 top to bottom.
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.Bechtel Associates ProfessionalCorporation Consumers Power Company BLC-3948 Page 3
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10.
Remove the Icak chase channel and 1/4" liner p' ate around the embedment at elevation 691'-0" and azimuth.2550-31'.
11.
Test leak chase at azimuths 250 and 270.
CONCRETE:
12.
No particular attention as to the removal of the spalled concrete is required. A sample of approximately 100 lbs. of the larger size concrete rubble shall be retained, all other concrete rubble may be disposed of.
13.
Clean off exposed concrete surface following all cracks to sound concrete.
BASE SLAB:
14.
Clean out the debris between the liner plate and base-slab.
Later, the following directions were added:
15.
Chip out about an 8"x8" trench of the cover slab at the bottom of the liner plate panel.
Care must be exercised not to damage the
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leak chase channel between the liner and the 1/2" knuckle plate and the reinforcing bars. This trench should be extended about 6" on each side of the L'14X61 columns at azimuths 250 and 270 degrees.
This chipping shall be done after the loose concrete above this area has been removed to preclude any debris falling into this trench. Alternately, the field can proceed with the trench before the loose material above is completely removed, providing measures to maintain the trench free of debris are provided.
16.
Test leak chase between liner and knuckle plate at El. 595; also r6 dial leak chase channels on the knuckle plate joints at azicuchs 250, 260 and 270 degrecs.
CORE DRILLINC:
17.
Remove a 5"x5" squarc of the 1/4" liner plate (without using a burning torch) at the following two location:
Center of squarc at 2'-9" from the centerline of the Icak a.
chase channel at the 270" strong back toward azimuth 280, and at elevation 598'-0".
' b.
Center of.squarc at 2'-3" from the centerline of the Icak chase channel at the 250 strong back toward azimuth'240",
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and at cicvation 598'-0".
Bechtel Asuciates Professional Co[poration Consumers Power Company BLC-3948 Page 4 Take precautions to keep the concrete behind the removed squares intact.
18.
Ar the center of the exposed squarcs, core drill, perpendicular to the wall, to obtain cylinderical core specimens 2.5" in diameter and 6" long.
If concrete degradation is noted behind the removed squares, do not core drill and notify engineering.
'19.
Core drill at the hair crack at about azimuth 260 and clevation 647 on the exterior of the reactor building perpendicular to the wall to obtain cylinderical core specimens of 1.5" in dismeter and in segmcats of 3" long; one, two or three segments maximum can bc core drilled depending on how deep this crack is and is decided by engineering.
20.
Note that complete records of removal and core drilling is required and that this work shall be carried out with the presence of engineering representative at the jobsite.
21.
Do not' fill the core-drilled examination holes until notified by project engineering.
22.
Please be advised that additional core drilled holes may be requested by the project engineering representative as necessary to. support our investigation.
PIPE RDIOVAL:
, Initial direction included:
2 3'.
Fill the water line from the bottom at a very low rate.
Keep a record of the pressure and detect any leaks inside the building.
24.
Chip out around pipe where Icak exists to expose the leaking area of the pipe as directed by project engineering representative at jobsitc; if neccssary fill pipe with water again to help project engineering representative locate the Icaking area.
Later, the following instructions were added:
25.
acmove a section of the 2"0 water pipe which appeared to be'lcaking during the hydrostatic test.
Limits of such removal shall be as directed by the engineering representative ~ at the jobsite.
26.
Take photographs of the pipe section before and after removal of, the pipe.
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Bechtel Associates Professional Corporation Consumers Power Company BLC-3943 i
Page 5 TEST liLOCKS:
27.
Make 6 blocks l'-0"x2'-0"x2'-4" cach, and 3 blocks l'-0"x2'--0"x3'-6" each, of the concrete mix used in the next lift of exterinr cor. crete vall of containment Unit 2.
These blocks should all be made from the same truck load. Also from the same truck load, make 6 test cylinders 6" diameter x 12" height for performing strength tests.
Curing 'of the blocks should.be carried out at the jobsite in a way similar to that in use for curing the walls "
The above directions have been uacd by Construction to obtain necessary
.information for the investigation of the liner plate failure, and also for the development of appropriate repair procedure alternates.
Picase advise if you,have further questions on this item.
Very truly yours,
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.'L. Castleberry
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i Project Engineer RSE/j t 4/15/4
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