ML19210D518
| ML19210D518 | |
| Person / Time | |
|---|---|
| Site: | Midland |
| Issue date: | 10/15/1979 |
| From: | Gibbs M ISHAM, LINCOLN & BEALE |
| To: | Cowan F, Linenberger G, Smith I Atomic Safety and Licensing Board Panel |
| References | |
| NUDOCS 7911270242 | |
| Download: ML19210D518 (2) | |
Text
-,
'.*f ISHAM, LINCOLN & BEDTED CORRESPONDENQ3 COUNSELORS AT LAW O
D ONE FIRST NATIONAL PLAZA FORTY-SECOND FLOOR
/
CHICAGO,lLLINCIS 60603 N,
TELEPHON E 312-558-7500 TELEM:2-5288 N
T WASHINGTON OFFICE
/
q'a
,q[
].,
'050 17T STRE ET, N. W.
.7 f =.-
SEVENTH FLOOR Wa s M tMGTO N. O. C. 2 OO3 e p*
set 1 202-833-9730 October 15, 1979 CD Ivan W. Snith, Esq.
Mr. Gustava A. Linenberger Atomic Safety and Licensing Board Atomic Safety and Licensing Bd. Panel U.S. Nuclear Regulatory Commission U.S. Nuclear Regulatory Commission Washington, D.C.
20555 Washington, D.C.
20555 Dr. Frederick P. Cowan Apt. B-125 6152 North Verde Trail Boca Raton, Florida 33433 Re:
Consumers Power Company (Midland Plant, Units 1 and 2)
Docket Nos. 50-329, 50-330 Gentlemen:
Enclosed is an interim S50.55 (e) report which has recently been submitted by Consumers Power Company to the Nuclear Regulatory Commission.
Very truly yours,,
bj i
q I
Martha E. Gibbs MEG:mc cc:
Service List Enclosures 1396 005 7 9112 70 M M 6
\\
SERVICE LIST Co m sp0NDENc3 9
Ivan W. Smith, Esq.
Ms. Mary Sinclair Atomic Safety and Licensing Board 5711 Summerset Street U.S. Nuclear Regulatory Comn.
Midland, Michigan 48640 Wa."hington, D.C.
20555 Colleen P. Woodhead, Esq.
Mr. Gustave A. Linenberger Counsel for the NRC Staff Atomic Safety & Licensing Bd. Panel U.S. Nuclear Regulatory Comn.
U.S. Nuclear Regulatory Comn.
Washington, D.C.
20555 Washington, D.C.
20555 Atomic Safety and Licensing Dr. Frederick P. Cowan Board Panel Apt. B-125 U.S. Nuclear Regulatory Comn.
6152 North Verde Trail Washington, D.C.
20555 Boca Raton, Florida 33433 Atomic Safety and Licensing Frank J. Kelly, Esq.
Appeal Panel Attorney General of the U.S. Nuclear Regulatory Comn.
State of Michigan Washington, D.C.
20555 Stewart H. Freeman, Esq.
~
Assistant Attorney General Gregory T. Taylor, Esq.
Myron M. Cherry, Esq.
Assistant Attorney General 1 IBM Plaza - 4501 Environmental Protection Div.
Chicago, Illinois 60611 720 Law Building Lansing, Michigan 48913 Mr. C. R. Stephens Chief, Docketing and Service Mr. Wendell H. Marshall Section R.F.D.
10 office of the Secretary Midland, Michigan 48640 U.S. Nuclear Regulatory Comn.
Washington, D.C.
20555 Grant J. Merritt, Esq.
Thompson, Nielsen, Klaverkamp & James 4444 IDS Center Minneapolis, Minnesota 55402 cu.
/
' E/
gY hb o
WS #[5 tE Og 9 a;sidhg:;
i-a e
o a
c
)
f.
,,, ;g p(,3 h000(
- g. rT
- Stephen H. Howell
- (
{Qyfly Senior Vice President General Of fices: 1945 West Parnell Road, Jackson, Michigan 49201. (517) 788 0453 Septe=ber 28, 1979 Hove-251+-79 N
n>
s Mr J G Keppler, Regional Director
[g g#
Office of Int iection ani Enforcement US Nuclear Re ulatory Ccanission Region III
,Z gTS "5
9 799 Roosevelt Road
}
@T MO Glen Ellyn, IL 60137 cy$
6 s
MIDLAND NUCLEAR PIANT -
UNIT NO 1, DOCIef n0 50-329 ea UNIT NO 2, DOCKET NO 50-330 C01EAIIMENT BUILDING PRESTRESSING TERDONS Refarenec: S H Eovell letter to J G Keppler; Midland Nuclear Plant; Unit No 1, Docket No 50-329; Unit No 2, Docket No 50-330; Containment Building Prestressing Tendons; Serial Hove-226-79; dated August 23, 1979 The referenced letter was an interim 50.55(e) rerort, as is this letter, on tendon viras which were in nonconformance to length requirements. The enclosure provides the status of resolution of this condition.
Another report, either interim or final, vill be sent on or before October 31, 1979 "h.
&k wRs/lr
Enclosure:
MCAR-33, Interim Report dj2, dated September 10, 1979 CC: Director of Office of Inspection and Enforcement Att~: MrVictorStello,USImc(15)
Director, Office of Management f j 9[j n
Infoz=ation and Program Control, USIGC (1)
Ub[
2 Hove-254-79
,)
O BCC: JLBacon, M-1085A RCBau=an, P14-412 WRBird, JSC-216B LHCurtin, Bechtel AA JLCorley, Midland LALreisbach, Bechtel-Midland GSKeeley, P14-408B BW4arguglio, JSC-220A DBM111er, Midland WMoring, Bechtel AA JIRutgers, Bechtel AA CAHunt, P14-209B GTBlack, Midland MEGibbs, II&B File: 0.4 9 30 e
e.
6 O
9 M
M 1
g NS 9
Hove-2%-79 Bechtel Associates ProfessionalCorporation s
SUBJECT:
HCAR 33 (issued 7/27/79)
Differential Vire Length of Contain=2nt Building Prestressing Tendons INTERIH REPORT 2 DATE:
Septecher 10, 1979 PROJECT:
Consumers Power Company Hidland /lant Units 1 & 2 Bechtel Job 7220 Introduction This report su==arizes Bechtel actions and evaluation regarding the differential length of wires in prestressing tendons.
Description of Deficiency During an inspection of the Inryeo Wiremil facility on July 19, 1979, Inryco and Bechtel personnel discovered that the back-tension cla=p of the wire shear was not functioning during f abrication of tendon H32-246.
Tne electrical panel controlling the tendon fabrication line was examined and the automatic back-cension selector switch was found in the off position for an unknown period of time.
The wires for tendon H32-246 vere scrapped.
Ten percent of the wires (17 wires) for tendon H32-249',
produced earlier in the day were re=oved from the anchor head and examined for length.
There was a length differential of + 1 inch." .
It was unknown whether the back-tension device was in the on or off position when these wires were cut.
The switch was turned on, four vires were run to length, sheared, and noted to 'be as much as 7 inches longer than the wires sheared when the switch was in the off position.
A hold was placed by Inryco on all 38 tendons which were fabricated, at the Wiremil facility and fabrication was discontinued.
The status of the 38 tendons is as follows:
1)
Twenty two tendons (7 vertical and 15 horizontal) were shipped to the Midland site.
The break-down is as follows:
a)
Seven vertical tendons were installed.
O.
b)
Five horizontal tendons were returned to Wiremil upon arrival at Midland.
c)
Ten hori=ontal tendons were stored at Midland.
I396 309 e=
Bechtel Associates ProfessionalCorporation i
MCAR 33 Interim Report 2 September 7.0, 1979 Page 2 2)
Sixteen tendons (7 vertical and 9 hori=onta'1) were not shipped to-Midland.
These tendons were stored at the Wiremil facility.
NCR 2373 was issued on July 24, 1979, placing ths tendons at the site on hold with QC hold tags attached to each tendon.
The differential wire length problem discovered at the Wiremil facility is in violation with the tendon and wire length tolerances given in the Midland FSAR Subsection 3.8.1.6.3.1 which states, "the differential length of any two wires in the sa=e tendon up to 100 feet wire icngth is j 1/16-inch and i 1/8-inch for wires longer than 100 feet.
Cutting tolerances for overall tendon length is j-1/2-inch up to 100 feet and +,
1-inch over 100 feet."
Investigation An investigation was initiated at both the Wiremil and Melrose Park facilities by Bechtel and Consumers Power Company personnel in the following areas.
~
1)
Hanufacturing Processes
.Melrose Park Facility, Illinois Helrose Park employs a mechanical fail-safe system such that a constant tension has to be applied to the wire and a mechanical end stop engaged prior to the shearing ac the wire.
Several atte= pts at shearing wires at shorter than set lengths were unsuccessful, attesting that the fail-safa mechanics of manufacturino the tendons are effective. Accordingly, the tendons produced at Melrose Park are not affected.
Wiromil Facility, Florida The mechanical operations at Uiremil are different from those at
. Helrose Park.
The wire is drawn from a coil rack, passing through the driving pinch rolls and wire sheac.
The wire is driven through the runout guide at high speed until it passes a photo-c1cceric cell in front of the catcher assembly.
The photo-electric cell activates a brake which slobs the wire until it engages the length-gage stop switch in the catcher assembly, which in turn activates the wire clamp.
The pinch rollers reverse to back tension the wire and the wire shear automatically cuts the wire, once the wire enters the catcher assembly, the operations are automatic and nearly simultaneous.
The following deficiencies were observed at
-Wiremil.
1396 010 e
Bechtel Associates ProfessionalCorporation g
HCAR 33 Interim Report 2 September 10, 1979 Page 3 a)
The switch controlling the back-tension devico. was situated on the control panel enabling it to be switched to the off position inadvertently by the operator.
b)
The end stop limit switch had a built-in toler.tnce which may have allowed wires to be cut to lengths exceeding acceptable variance tolerance.
c)
The end cla=p assembly had the possibility of allowing the wire to slip during back-tensioning, due to a structural defect (weld crack) in the end clamp assembly and possibic low air pressure.
2)
Quality Control Procedures At the Melrose Park facility, differential wire length was checked
~
periodically by Inryco personnel; hcwever, no data was recorded.
No such checks were made at the Wiramil facility.
A QC program change has been made to check and record differential wire lengths (see corrective action for details).
The duties of QC and production Bechtel personnel were not well-defined at the Wiremil facility.
also expressed concern regarding other areas of Inryco's quality Further investigation was to be accomplished by Bechtc1's program.
quality program verification.
~
Safety Imolications Project engineering's investigation indicates that the quality assurance program used at the Wircmil f acility broke down.
The differential wirc lengths in a tenden will cause wire stresses in excess of the desige values.
The safety margin of the containment structure is thus reduced from the design con itions as stated in the FSAR.
Therefore, the defici-d is considered reportable under 10 CTR 50.55(e). However, the enc; situation probably would not have an adverse effect on plant safety for the following reasons:
"1)
A tendon is subjected to the maximum stress during the initial prestressing operation, when they are stressed to 80% of the ult 1= ate strength. Therefore, if a tendon can withstand the initial prostress-ing force, it will not fail during any design condition.
2)
Since a tendon experiences the highest stress level during the initial prestressing operation, wires that are overstressed may break.
The condition would have been detected as a part of specifi-cation requirements for broken wire.
l396 01I
~
~
Bechtel Associates ProfessionalCorporation s
HCAR 33 InterLa Report 2 September 10, 1979 Page 4 During the prestressing operation, the jacking force is monitored 3) with calibrated gages and the tendon elongations are checked against calculated values.
Any abnormality would be detected and corrective massures would be made.
Corrective Action The deficiencies in the manufacturing processes observed at Wiramil are corrected as follows.
1)
The back-tension device has been put in an on position and the switch re=oved from the control panel to prevent it from being turned off.
2)
The end stop limit switch has been replaced by a switch with 0.057-inch tolerance.
3)
The end clanp assembly has been structurally reinforced, and a pressure regulator has been added to ensure constant air pressure.
To preclude any system deficiencies from being left undetected for undetermined periods of time, a quality control inspection procedure, QC 5.1.1, was developed by Inryco.
The procedura describes a method and frequency with which to measure and record the differential lengths of two wires sheared on the tendon production line.
The procedure was approved by Bechtel on August 17,-1979, and had been impicmented at the Melrose Park and Wiremil facilities.
The areas of concern in Inryco's quality program at Wiremil were addressed during a Bechtel suppliar quality department's quality program verification.
Inryco's resolution was found to be satisfactory and the hold on the tendon production at Wiremil was lifted.
Disposition 1)
Inryeo will submit a tendon length correction procedure for evaluation by Bechtel for the 7 vertical tendons installed.
2)
If Inryco's tendon 1cngth correction procedure is successful in eliminating the excessive wire differentials in the 7 installed vertical tendons, then the 7 vertical tendons which are being held at Wiremil may be corrected using the same method.
1396 012
Bechtel Associates ProfessionalCorporation s
HCAR 33 Interim Report 2 September 10, 1979 Page 5
~
3)
The ten horizontal tendons stored at Midland were returned to Wiremil on the week of September 10, 1979. All 24 horizontal tendons fabricated at Wiremil will not be used as originally iatended.
The materials c.ay be reworked for fabrication of rhorter vertical tendons.
Submitted by: AC #' ~ - _
Approved by:,4 44CM./ M M
. Consurrence by:
EAR /js 9/4/2 1396 O.l3
,