IR 05000498/1987048
| ML20237C323 | |
| Person / Time | |
|---|---|
| Site: | South Texas  |
| Issue date: | 12/15/1987 |
| From: | Callan L NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| To: | Goldberg J HOUSTON LIGHTING & POWER CO. |
| References | |
| NUDOCS 8712210250 | |
| Download: ML20237C323 (2) | |
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i In Reply Refer To:
rcr. ! 5195T Dockets: 50-498/87-48 50-499/87-48 Houston Lighting & Power Company ATTN:
J. H. Goldberg, Group Vice President, Nuclear P.O. Box 1700 Houston, Texas 77001 Gentlemen:
Thank you for your letter of November 12, 1987, in response to our letter and Notice of Violation dated September 22, 1987. We have reviewed your reply and find it responsive to the concerns raised in our Notice of Violation. We will review the implementation of your corrective actions during a future inspection to determine that full compliance has been achieved and will be maintained.
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L. J. Q La L. J. Callan, Director Division of Reactor Projects
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Houston Lighting & Power Company ATTN:
M. Wisenberg, Manager Nuclear Licensing P.O. Box 1700 Houston, Texas 77001 Houston Lighting & Power Company ATTN: Gerald E. Vaughn, Vice President
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Nuclear Operations P.O. Box 1700 Houston, Texas 77001 RIV:DRP/D [f3 DRP/DNf//w DRP
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,7 HBundy:gb GLConstable LGCallan A//f/87 ff/py/87 p/pj/87 1 \\
8712210250 871215 PDR ADDCK 05000490
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Houston Lighting and Power
Company Central-Power & Light Company ATTN:
R. L. Range /R. P. Verret P.O. Box 2121 Corpus Christi, Texas 78403 City Public Service Board ATTN:
R. J. Costello/M. T. Hardt
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P.O. Box 1771 San Antonio, Texas 78296 City of Austin ATTN:
M. B. Lee /J. E. Malaski
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Austin, Texas 78767-8814 Texas Radiation Control Program Director bec to DMB (IE01) - DRP and DRS bec distrib. by RIV:
- DRP
- RRI-0PS R.~ D. Martin, RA
- RRI-CONST.
- SectionChief(DRP/D)
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- RIV File
- Lisa Shea, RM/ALF
- RSTS Operator R. Bachmann, OGC
- H. Bundy
- P. Kadambi, NRR Project Manager
- R. Taylor
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- R. Hall
- DRS D. Powers
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,1 November 12, 1987 ST-HL-AE-2414 File No.: G2.4 10CFR2.201 hh
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U. S. Nuclear Regulatory Commission js
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d Attention: Document Control Desk
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Washington, DC 20555 South Texas Project
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Unit 2 Docket No. STN 50-499 Response to Notice of Violation 8748-01 Reference:
HL&P Letter ST-HL-AE-2394 dated October 23, 1987; M. R. Wisenburg to USNRC Document Control Desk.
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Houston Lighting & Power Company has reviewed Notice of Violation 50-499/8748-01 dated September 22, 1987 and submits the attached response pursuant to 10CFR2.201.
A submittal date extension was granted by Mr.
G. L. Constable as documented in the reference.
If you should have any questions on this matter, please contact Mr.
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J. S. Phelps at (512) 972-7071.
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J. H. Go dberg Group Vice Presi ent, Nuclear JSP/hg Attachment:
Response to Notice of Violation (50-499/8748-01)
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Revised 10/15/87
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Attachasnt
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File No.: G2.4
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Rilsponse'to Notice of Vioiati6n 8748-01
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I. Sk$tSuent of Violition -
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Criterion V,of Append 14 B to,10' CFR Part' 50" requires that activf. ties
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. y).affecting quality be ptescribed by and accomplished in accordance with I
- appropriate pastruetions, procedures, or drawings. This requirement'is i
~ Eamplified by;the approved Quality Assurat.tc3 Program Description (QAPD) of South Texas Project (STP).
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Standard Site Procedure (SSP) 38, Revision 1, paragraph 5.9, references Specification 5V279VS1003, Revision 7 " Installation of Safety and'
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Non-safety HVAC Equipment and.Ductwork." Paragraph 3.12 of this specificat' Ion states, " Bolts and nuts for. galvanized ductwork shall be
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hot-dipped galvanized. cadmium-plated, or electromagnetic zine-coated.
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' Hot-dipped galvanized nuts shall only be used.with hot-dipped galvanized
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bolts.
Cadmium-plated and electromagnetic zine-coated nuts may be used s
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with either cadmiwn plated or electromagnetic zine-coated bolts."
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Con t r-.,, to the Ab'ovo, hot-dipped galvanized nuts were used with o
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electromagnetic zine-coated bolts, and hot-dipped
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used/vith electromagnetic zire einted. nuts.
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Salvanized bolts were jl Thikis a Se3erity Level IV violaticn-if
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- II. Reason for Violation
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Construction' failed to take measures, prior to September 1986, to prevent commingling of bolting materials during HVAC duct installations. hi addition, similarities in appearance of hot-dipped galvanized and electror.ag@ tic zine-coated materials made it difficult to identify commingle 6(bolts and nutsfduring visual inspection.
Corrective action t.eken to resolve the problem for Unit 1 (identiff ed in September 1986)
. did not completely address the duct which was already installed in Unit 2.
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/ III. Corrective Action Taken and Results Achieved
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,i Two Nonco formance Reports (NCRs) were generated to docuw nt.the suspect a
condition.
Additional investigations performed by Bechtil Engineering as
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part of NCR disposition disclosed that six (6) out of thirty-wo (32)
suspect bolts / nuts sampled did not meet the requireinent of the
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specification.
As a result of the earlier problem in Unit 1 (Saptember 1986),
construction' personnel were instructed to use only black electromagnetic zirn coated bolting for installation of duct flanges.
Construction;
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personnel vore also instructed at that time to purge HVAC working l
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locationsofboltingmaterialexceptthej>1tekboltsandnuts.
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Attachment l4 4 2
ST-ML-AE-2414
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File No.: G2.4 Page 2 of 4 s
A surveillance was performed during January 1987, to verify that bolting
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materials other than the black bolts and nuts had been purged from work areas.
The surveillance concluded that only the black bolts and nuts were being used for duct flange installations.
To assess the extent of the problem in Unit 1, a curvey was performed of over 3000 nut / bolt combinations in September 1986. Only seven (7) cases of commingling were identified (0.23%) from the total sample. During October 1987, a survey of Unit 2 installations was conducted which included approximately 5 percent of the safety-related ductwork. This survey involved 5750 bolt / nut installations distributed among 265 duct flanges.
The results revealed 150 cases of commingling in 25 flanges (approximately 2.6%).
Although this percentage was low, extensive commingling existed on 8 of the flanges. As a result of the extensive commingling on the 8 flanges, as well as the conditions documented on the NCRs, testing was performed by Bechtel to demonstrate the adequacy of flanges containing commingled nuts and bolts.
Initially, tensile load testing was performed on specimens of commingled bolt and nut assemblies as part of NCR disposition.
Twelve specimens of bolt / nut assemblies, consisting of four 3-specimen sets representing matched and commingled galvanized and electromagnetic zine-coated (or electroplated) material, were tested to determine their tension ultimate load. Results of the tests indicated that the ultimate load for the specimens of commingled bolts and nuts exceeded the specified minimum ultimate load.
Therefore, the tensile load capacity was not degraded by the thread incompatibility introduced by commingling of bolting material.
Although the three specimens which represented the loose fit of electroplated bolts with oversized galvanized nuts exhibited failure by thread-stripping instead of the preferred failure by elongation of the bolt shank, the specified minimum ultimate load was exceeded in all cases.
As a result of the Unit 2 survey, additional tensile testing of bolt / nut assemblies was performed using two specific types of electromagnetic zine-coated (or electroplated) bolts (EPTB: as-coated bolts, manufactured by Texas Bolt; and EPMD: cleaned and polished bolts, manufactured by Maryland Bolt and Nut Company) plus galvanized (HDG) bolts.
These were combined with galvanized (HDG) and electroplated (EP) nuts to obtain the following bolt / nut combinations of concern: HDG/EP, EPMD/HDG and EPTB/HDG.
For each combination, 6 specimens were tested to failure, 3 specimens were tested to the allowable design load, and 3 specimens were tested to the allowable faulted load (1.5 X design load).
The test results are as follows:
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For all tests to failure, the ultimate load exceeded the specified minimum ultimate load of 4600 lbs., except one EPTB/HDG specimen that failed by bolt breakage at a lower load.
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ST-HL-AE-2414 File No.: G2.4 Page 3 of 4 2.
All failure modes were by elongation and/or breakage of the bolts.
No failures were due to stripping of the threads that could have been anticipated due to the loose fit obtained when galvanized nuts (furnished with oversized threads) are installed on electroplated-bolts (furnished with nominal size threads).
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.None of the specimens which were tested to and held at the specified allowable loads,' including the specimens tested to failure, exhibited any evidence of thread damage.
L The bolt / nut tightness attained in matched and commingled assemblies was evaluated by measuring and comparing the resisting torques developed in representative specimens installed and tightened under controlled, nearly identical conditions. The resisting torque is a valid direct indicator of the ability of the bolt / nut assembly to remain tightly engaged during service conditions since the torque is what prevents the nut from rotating loose from the bolt. A test companion flange was assembled with thirty fasteners representing each of the five following bolt / nut combinations by 6-specimen sets:
EPMD/EP, EPTB/EP, HDC/HDG, EPMD/HDG, EPTB/HDG The fasteners were tightened fo11ow1.,g a fixed, controlled sequence to assure equal representation of each combination at various stages of tightening. The initial (Level I) tightening was selected to represent the actual installation procedure in which the tightened condition is established when the lockwashers are flattened.
That procedure provides a nominal non-exacting tightening which is consistent with the type of bolts used (non high-strength, A-307).
This is adequate for the ductwork service. The resultant torque, however, is low and not easily measured.
Accordingly, the comparison of the low torque values was inconclusive and a higher (Level II) tightening, corresponding to a half-turn as provided by the AISC " turn-of-the-nut" method, was introduced to obtain higher, more easily compared torque values. Neither test level indicated a distinct trend toward the development of lower resisting torques in the combinations of electroplated bolts with loose-fitting galvanized nuts.
The Level II test results permitted quantification and averaging of the torques developed for the six specimens representing each of the five combinations, and they compare as follows:
BOLT / NUT lbs.)
COMBINATION TORQUE AVG. (Ft.
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EPMD/EP 10,67 EPTB/EP 6.25 HDG/HDG 9.75 EPKD/HDG 7.25 EPTB/HDG 6.50 ALL Combinations 8.08 14/NRC/mf
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ST-HL-AE-2414 File No.: G2.4 Page 4 of 4
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I The torques developed in the commingled nut / bolt combinations are comparable with the others.
Based on the tensile load and torque tests, HMP has concluded that the duct flanges installed with commingled nuts and bolts are acceptable since neither structural integrity or the tightness of the flange connections have been degraded.
The test results will be used as the basis for acceptance of commingled flanges installed in Unit 2.
IV. Corrective Steps Taken to Prevent Recurrence l
l Because the testing described above has demonstrated that any combination l
of bolts and nuts used for HVAC duct installations are technically l
acceptable, HMP believes that no recurrence controls are required.
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However, in order to provide clear and explicit direction to the constructor, the applicable procedure will be revised to require the use of black electromagnetic zine-coated bolting material for future installation of duct flanges.
The specification will be revised to allow the use of any combination of bolting material (hot-dipped galvanized, cadmium or electromagnetic zinc-coated).
In the event that the supply.of black electromagnetic zinc-coated bolting material becomes exhausted, the
existing stock of other types of bolting material permitted by the I
specification will be utilized.
The procedure and the specification will
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be revised by November 20, 1987.
As a result, the requirement for QC verification of the nut and bolt combinations will be deleted.
V. Date of Full Compliance STP is presently in full compliance with the revised program as described above; the procedure and specification will be revised by November 20, 1987.
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