ML20149D645

Special Rept 87-002:voids in Tendon Sheathing Grease in Excess of 5% Net Duct Vol Detected During Surveillance. Containment Structural Integrity Demonstrated

ML20149D645
Person / Time
Site:	Vogtle
Issue date:	01/06/1988
From:	Gucwa L GEORGIA POWER CO.
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
References
87-002, 87-2, SL-3953, NUDOCS 8801130070
Download: ML20149D645 (6)

Text

• Geona Power Cornpany

. ,, ' 333 Piedmont Avenue Attanta, Georgia 30308 Telephone 404 5264526 Ma ling Ad$ess:

Post office Box 4545 Atlanta, Georgia 30302

, Georgia Power lic shA? Mil e:rci?C Stlte Manager Nuclear Safety .

and Ucensing SL-3953 0722m X7GJ17-V540 January 6, 1988 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Hashington, D.C. 20555 PLANT V0GTLE - UNIT 1 NRC DOCKET 50-424 OPERATING LICENSE NPF-68 SPECIAL REPORT 87-002 CONTAINMENT TENDONS STRUCTURAL INTEGRITY Gentlemen:

In accordance with the requirements of the Plant Vogtle Unit 1 Technical Specification sections 3.6.1.6.b and 6.8.2, Georgia Power 1 Company is submitting the enclosed Special Report concerning the

, containment tendons structural integrity. A copy of this submittal is 4

being provided to the NRC Region II office for review.

Si erely,

& RI L. T. Gucwa .

PAH/lm i

Enclosure:

Special Report 50-424/1987-002 c: (see next page) 1

)

1 I

8801130070 880106 PDR ADOCK 05000424 i

fM gV ,p i

S . _

asa.

P6A

Georgia Powerkn U. S. Nuclear Regulatory Commission January 6, 1988 Page Two c: Georgia Power Comoany Mr. J. P. O'Reilly Mr. P. D. Rice Mr. G. Bockhold, Jr.

Mr. C. H. Hayes Mr. J. E. $wartzwelder GO-NORMS Southern Comoany Services Mr. R. A. Thomas Mr. J. A. Bailey Shaw. Pittman. Potts & Trowbr_idge Mr. 8. H. Churchill, Attorney-at-Law Troutman. Sanders. Lockerman & Ashmore Hr. A. H. Domby, Attorney-at-Law U. S. Nuclear Regulatory Commission Dr. J. N. Grace, Regional Administrator Mr. J. B. Hopkins, Licensing Project Manager, NRR (2 copies)

Mr. J. F. Rogge, Senior Resident Inspector-0perations, Vogtle 0722m 7M77$

GeorgiaPower A ENCLOSURE PLANT V0GTLE - UNIT 1 NRC DOCKET 50-424 OPERATING LICENSE NPF-68 SPECIAL REPORT 50 424/1987-002 A. REOUIREMENT FOR REPORT The Plant Vogtle Unit 1 Technical Specification 4.6.1.6.1, Containment Tendons, requires that the containment tendons' structural integrity shall be demonstrated at the end of 1, 3, and 5 years following the initial containment vessel structural integrity test and at 5-year intervals thereafter.

Technical Specification 3.6.1.6.b. states:

"With any abnormal degradation of the structural integrity other than Action a. at a level below the acceptance criteria of Specification 4.6.1.6, restore the containment to the required level of integrity within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> and perform an engineering evaluation of the containment and provide a Special Report to the Commission within 15 days in accordance with Specification 6.8.2 or be in at least HOT STANDBY within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in COLD SHUT 00HN within the following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />."

Technical Specification 4.6.1.6.1.e. states:

"Verifying the OPERABILITY of the sheathing filler grease by:

1) No voids in excess of 5% of the net duct volume,

2) Hinimum grease coverage exists for the different parts of the anchorage system, and

3) The chemical properties of the filler material are within the tolerance limits as specified by the manufacturer."

Since voids in excess of 5% of the net duct volume were detected during the recent surveillance, a special report is required to be submitted to the NRC in accordance with Technical Specification 3.6.1.6.b and 6.8.2.

0722m E-1 01/06/88 SL-3953

\

1. ^

.. .e Georgia Power d ENCLOSURE (Continued)

SPECIAL REPORT 50-424/1987-002 B. DISCUSSION OF THE TENDON SURVEILLANCE AND ITS RESULTS Technical Specification 4.6.1.6.1.e.1 requires that the operability of the sheathing filler grease be assured by verifying that no voids exist that are in excess of 5% of the net duct volume. In order to assess this void percentage in horizontal tendons, hot grease is pumped in one end of the tendon until grease exits the opposite end.

If no grease exits, the pumping operation is transferred to the other end of the tendon. The veld is determined in vertical tendons by opening the top grease vent and pumping grease from both ends to force grease from the top vent. If no grease is emitted, hot grease is poured or pumped into the top vent to completely fill the sheathing void. Pumping pressure is limited to 150 psig on vertical tandons an) 100 psig on horizontal tendons to prevent sheathing damage.

The void is calculated by taking the total grease added, subtracting the total grease lost, and dividing by the net duct volume.

The surveillance results are shown in Table 1. Horizontal tendons H-149, H-14, H-88, and H-49 exhibited voids in excess of 5%. Tendon H-69 exhibited a void of approximately 5%. 1he remaining tendons did not exhibit any voids in excess of 5% and are therefore considered acceptable per the requirements of the unit's Technical Specifications.

C. ENGINEERING EVALUATION The procedure used by the Georgia Power Company Construction Department for installing the tendons assured a high degree of corrosion protection for the tendons. The tendons were handcoated with Visconorust 2090 P-4 as they were pulied into the sheathing.

Additionally, the tendons were coated with a temporary corrosion preventive material at the factory. During the greasing procedure, vents were opened to allow the release of air bubbles. Hot grease was pumped until a clear flow of grease was observed exiting the appropriate vent. This process ensured that the tendons received a thorough coating of grease. .

l Visconorust 2090 P-4, which is manufactured by the Viscosity 011 i Company, provides an effective barrier to moisture and air which i retard the effect of a corrosive atmosphere. The grease provides a protective film which is not easily penetrated by free water and 0722m E-2 01/06/88 SL-3953 SDr75

o 1- ,

GeorgiaPower d ENCLdSURE(Continued)

SPECIAL REPORT 87-002 which has a reserve alkalinity for long term acid neutralization. The film aids in rstarding corrosion introduced by water soluble ions from chlorides, nitrc.tes, and sulfides. (It should be noted that samples of grease taken during the surveillance tests are being tested to determine the reserve alkalinity of the grease. Test results are expected at the end of January, 1988. If the test results are not satisfactory, a supplemental report will be submitted to the NRC).

Resylts from the first year tendon surveillance revealed voids in excess of 5% for four of the tendons surveyed. There are several factors that could reduce the voids measured to a value less than 5%.

4) The machining tolerance on the wires, trumpets, and other machined components could have increased the void by one percent.

2) Shrinkage of grease during construction may have been higher '

than 7%. Visconorust 2090 P-4 has a coefficient of expansion of approximately one percent (1%) for every 20 degrees Fahrenheit.

Initial filling temperature ranged between 150 and 220 degrees Fahrenheit. Cold weather conditions can cool the filler material and can cause a contraction.

3) The initial filling method may cause air entrapment in the filler material. Pumping operations can introduce air into the filler material which may add up to two percent of the net duct -

volume. The void v&lue could be higher for horizontai tendons  !

since the pumping head was lower than that used for vertical i tendons.

During this surveillance, the end anchorages of these tendons were inspected for corrosion, grease coverage, anchorage cracking, and strand condition. In addition, a strand was removed from a vertical and ,

horizontal tendon. A visual inspection revealed no evidence of active i corrosion during these inspections.

Based upon the inspections performed for corrosion, the characteristics of the grease, the construction process used to initially fill the ducts, and dimensional tolerances used in calculating the net duct volumes, it ,

can be concluded that the grease is providing adequate corrosion protection and that no abnormal degradation has occurred due to tendon sheathing grease voids in excess of 5%. The containment integrity has not been adversely affected by this condition.

0722m E-3 01/06/88 SL-3953 ,

s one .

A

GeorgiaPower A TABLE 1 l flRST YEAR SURVEILLANCE TENDONS NET VOLUME OF GREASE  :

ADDED TENDON VOLUME VOLUME GALLONS  % OF NET NO. OF OF DUCT VOLUME GREASE GREASE ADDED LOST

^

H-149 30.0 6.50 23.50 6.4%

H-14 36.0 13.0 23.00 5.1%

H-88 29.75 9.25 20.50 5.5%

H-49 49.00 20.25 28.75 7.5%

H-83 15.75 3.25 12.50 3.4% l H-45 32.15 14.50 17.65 4.7%

H-69 30.63 11.75 18.88 5.0%

H-126 23.75 12.25 11.50 3.1%

H-151 24.50 14.00 10.50 2.9% l H-139 20.25 7.50 12.75 3.4%

i V42-144 11.75 5.50 6.25 1.1%

V58-128 104.75 105.5 -0.75 -0.12%

V4-108 6.0 8.75 -2.75 -0.47%

V18-94 8.0 8.25 -0.25 -0.04%

0722m E-4 01/06/88 SL-3953 ers