ML20237J866
| ML20237J866 | |
| Person / Time | |
|---|---|
| Site: | Callaway  |
| Issue date: | 08/13/1987 |
| From: | Blosser J UNION ELECTRIC CO. |
| To: | NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM) |
| References | |
| 87-08, 87-8, ULNRC-1575, NUDOCS 8708180382 | |
| Download: ML20237J866 (5) | |
Text
_ _ _ _ _ _ - _ - _
w Etscraic a
August 13, 1987-CaHaway Plant U. S. Nucicar Regulatory Commission Document Control Pesk Wcshington, DC 20555 l
ULNRC-1575 Centlemen:
. DOCKET NUMBER 50-483 CALLAWAY PLANT UNIT 1 FACILITY OPERATING LICENSE NPF-30 SPECIAL REPORT 87-08 3RD YEAR INSERVICE CONTAINMENT VESSEL TENDON SURVEILLANCE FA_ILDR,E The enclosed Special Report is submitted pursuant to Technical Specification 3.6.1.6 ACTION b.and 6.9.2 dt.e to a failure of Surveillance Requirement 4.6.1.6.1.e.l.
The enclosed report contains an engineering evaluation of the containment vessel structural integrity and is submitted te meet the 15 day reporting requirement of Technical Specification 3.6.1.6 ACTION b.
Since the 3rd year surveillance is still underway, if required, a supplemental report will be issued to-identify any additional tendon surveillance failure (s).
Results of the first year inservice tendon surveillance were reported in Special Report 85-06, dated 7/24/85.
4 DBfw J. D. Blosser i
Manager, Callaway Plant 4 PSP:jl1 Enclosure cc: Distribution attached e41 8708180382 070813 PDR ADOCK 05000403 ij S
,a
_ Mailing Address
- P.O. Box 620, Futn, MO 65251
I cc distribution for ULNRC-1575 Mr. Thomas W. Alexion (2 copies)
Manager, Electric Department Office of Nuclear Reactor Regulation Missouri Public Service Commission U.S. Nuclear Regulatory Commission P. O. Box 360 Mail Stop P-316 Jefferson City, MO 65102 7920 Norfolk Avenue Bethesda, MD 20014 Mr. O. Maynard Wolf Creek Nuclear Operating Corp.
American Nuclear Insurers P. O. Box 411 c/o Dottie Sherman, Library Burlington, KS 66839 The Exchange Suite 245 270 Parmington Avenue Mr. Merlin Williams Farmington, CT cS032 Supt. of Regulatory Quality &
Administrative Services.
Records Center Wolf Creek Nuclear Operating Corp.
Instittite of Nuclear Power Operations P. O. Box 411-Suite 1500 Burlington, KS 66839
'1100 Circic 75 Parkway Atlanta, GA 30339 Mr. A. Bert Davis Regional Administrator U.S. Nucleer Regulatory Commission Region III 799 Roosevelt Road Glen Ellyn, IL 60137 NRC Resident Inspector D. F. Schnell (400)
R. J. Schukai (470)
G. L. Randolph J. F. McLaughlin J. E. Davis (240SR)
(Z40SR) (w/c)
D. W. Capone /R. P. Wendling (470)
F. D. Field (480)
A. P. Neuhalfen A. C. Passwater/D. E. Shafer/D. J. Walker (470)
G. A. Hughee Z170.05 (QA Record)
J. M. Price T. H. McFarland M. E. Taylor H. Wuertenbaechar, Jr. (100)
S. L. Auston (470)(NSRB)
S. J. Bellers/J. D. Schnack JDB Chrono 3456-0021.6 3456-0260 Z40ULNFC A160.761 N. Date (Sandra Auston) (470)-
f
. A+h e
. ~m u_ -
- _=a er
~
EVALUATION OF THE THIRD YEAR INSERVICE TENDON SURVEILLANCE FOR THE CALLAWAY NUCLEAR PLANT The Callaway Plant Technical Specification 4.6.1.6.1 requires the demonstration of containment structual inte rity through a surveillance of the c
containment post-tensioning system at the end of 1 5, 3 5, and 5.5 years following the initial structural integrity test, and every 5 years after. During the surveillance of the system af ter 3 5 years, which began July 6,1987, it was discovered that the net refill volume of the sheathing filler material exceeded 5%
of the net duct volume for surveillance tendon V18. This void condition failed to meet Tech. Spec. 4.6.1.6.1(e) which requires verification of operability of the (1) No voids in excess of 5% of the net sheathing filler material by assuring duct volume". Due to the fact that a void greater than 5% was discovered after tilling, action statemant 3.6.1.6.B was immediately satisfied. The NRC Staff concurred with this position in a meeting on the same subject for the first year I
surveillance on July 19, 1985 The Callaway containment building is a post-tensioned, reinforced concrete structure comprised of a vertical cylinder with a hemispherical dome roof and is supported by a reinforced concrete slab. A continuous access gallery is provided beneath the foundation slab for inspection of the vertical tendons. Three concrete buttresses are provided for anchorage of the horizontal tendons.
Anchorages are designed such that tendons can be detensioned, inspected and retensioned readily during the life of the plant. The vertical cylinder wall is provided with a system of vertical and horizontal (hoop) tendons. Vertical tendons are continuous tc form inverted U's that extend over the dome. The configuration of the ter. dons in the dome is based on a three-way system consisting of two groups of vertical tendons oriented at 90 degrees with respect to each other and a horizontal (hoop) group extending from the spring line to approximately 45 degrees from the horizontal. Hoop tendons in both the wall and the dome are placed in a 240 degree system in which three tendons form two Each tendon is complete rings using three buttresses for anchoring the tendons.
cumprised of 170 - 1/4"O wires, terminating at each end with a colo formed buttonhead at the anchorage fixture.
The essential criterion for the operability of the sheathing filler material is to prevent corrosion of both the tendon wires and the anchorage components.
The material used in the Callaway Plant post-tensioning system, Visconorust 2090P-4, accomplishes this by a characteristic which gives the filler material an affinity to adhere to steel surfaces, its ability to emulsify any moisture in the system which nullifies its rusting tendency, and by its resistance to moisture, mild acids, and alkalis.
In addition, protection is afforded by each tendon wire being individually pre-coated with a greass, Amber 1501, prior to installation.
Results frcm the first year tendon surveillance revealed voids in excess of 5%
for all tendons surveyed, without a loss of integrity to the system. From lab tests on the removed wires and grease, and from visual inspectica of the tendon components, the filler material is performing its intended function of prohibiting corrosion of the tendon.
The void in the V18 tendon sheathing, as indicated by the refill volume, was 6.2% of the net d_uct volume and may be attributed to a number of factors:
~
- 1) Visconorust 2090P-4 has a coefficient of expansion which yields an
- expansion of about-15 per every 20 F.
Initial. filling temperatures of the filler material averaged 160 F.
Cold weather conditions can cool the hw w
a w
een&wn 6
p yu m 1
I filltr c tsriel to 40 F, giving a contenction of 65 cf th2 n;t duct volum3. During tha third yttr innervica survaillanca of tha t ndons, tha
. temperature of insitu filler material averaged 90 F, giving a contraction
{
of 3 to 45 from initial fill.
I
- 2) Characteristics of the initial f1111ng method may induce air entrapment into the filler material. Pumping operations can introduce air into
)
filler material and may add up to as much as 25 of the net duct volume.
l The tendons at Callaway Plant were initially greased between April and October 981 by Inryco using current industry standard filling
- 3) During the initial filling operations, the tendon bundle was cold (ambient 1
temperature of 65 F) and as the heated filler material (exit temperature 4
of 140 F) was pumped into the sheathing void, it solidified on the surface of the tendon bundle, leaving small voids between the wires.
As the filler material gradually heated the tendon bundle, it is likely that the voids between the wires allowed migration of the f!13 er material into the tendon bundle. Because this process is slow and gra:1ual, it is reasonable to expect that it took place substantially af ter the filling l
operation was complete and possibly during the surveillance refill operation.
In addition, this type of migration could also occur at other areas such as where tendons are in contact with the sheathing.
'.n addition, visual inspection of the exterior concrete of the containment building after the initial greasing and during the surveillance t-evealed no signs of grease seepage from the tendon duct. Therefore, refill volumes in excess of the lost grease during the surveillance indicate that the void existed within the l
tendon duct boundary.
{
The Callaway Plant tendon V18 requiring net refill volumes of the filler material in excess of the 5% criteria has not shown any abnormal deterioration or degradation of strength. The lift-off force for that tendon has been found to fall within the predicted limits (see attachment 1, Preliminary Lift-Off Force Data Sheet). Laboratory examination of the filler material has not been performed as of this date but the grease has shown no signs of discoloration or water present in the grease. Visual inspection.cf the different components of the anchorage system revealed proper coverage by the filler material with ne signs of j
corrosion or presence of water.
As indicated by the above, the function of the filler materia' in protecting the post-tensioning system is being maintained.
As long as suff;cient filler material has been introduced into the system to completely coat the wires and anchorage system, corrosion protection is assured. Voids, such as those 3rienced at the Callaway Plant, can be expected due to the characteristics of the filler material and initial filling operations as noted above. Since each wire is individually pre-coated with Amber 1601., the degree of filling interstitial spaces, which comprise the net duct volume, is not directly related_
to the degree of coating which occurs, and therefore, is not a major indicctor of the operability of the post-tensioning system. Based on the lift-off results, visual inspection and results from the first year surveillance, we have concluded that the structural integrity of the tendon and anchorage system has not been adversely affected by the measured void.
Since compliance with all remaining surveillance requirements for Tech. Spec.
4.6.1.6.1 was demonstrated, it_is concluded that " voids in excess of 5% of the net duct voluh:e" have' not resulted in any degradation cf the post-tensioning system,~
assuring the structural integrity of the containment structure.
We w
e m
a se smem
N~G$W In cddition, future achsdulcd survaillancas of tha post-tansioning systra and full precsura int:grat1d leak rate tests will monitor th3 structural piramstors of the containment-to datect any potsntial abnormal degradation, assure continued operability of the system, and. verify containment srructural integrity on a continuing basis.
As the 3rd yeer surveillance is still underway, this report has been filed to meet the 15 day r.ction statement as specified in Tech. Spec. 3.6.1.6.B.
A supplemental report will be filed, should the laboratory test on the tendon V18 grease reveal abnormal results, or should any other tendon exceed the 55 void
-limit for grease.
I l
I l
1 w
o.
A
=
~
~
.a
~
y me
[
=e*
r
-