ML20138E178

Application for Amend to License NPF-42,revising Tech Spec Section 3/4.6.1.6 Re Containment Structural Integrity. Fee Paid

ML20138E178
Person / Time
Site:	Wolf Creek
Issue date:	12/06/1985
From:	Koester G KANSAS GAS & ELECTRIC CO.
To:	Harold Denton Office of Nuclear Reactor Regulation
Shared Package
ML20138E183	List: ML20138E178 ML20138E187
References
KMLNRC-85-264, NUDOCS 8512130362
Download: ML20138E178 (9)

Text

KANSAS GAS AND ELECTRIC COMPANY THE ELECTAC COMPANY GLENN L ROESTER vect .nt srosmt . muctaan Decerber 6, 1985 Mr. Harold R. Denton, Director Office of lbclear Reactor Regulation U.S. Ibclear Regulatory Comission h'ashington, D.C. 20555 KML?EC 85-264 RE: Docket No. STN 50-482 SUBJ: Revision to Technical Specification 3/4.6.1.6

Dear Mr. Denton:

The ptrpose of this letter is to transmit three (3) original and forty (40) conformed copies of an application for Ahendment to Facility Operating License No. NPF-42 for Wolf Creek Generating Station, Unit No. 1.

This application requests that Section 3/4.6.1.6, Containment Vessel Structural Integrity, of the Wolf Creek Generating Station

'Ibchnical Specifications be revised. This application for amendment revises ACTION b. and adds ACTION c. and d. associated with Technical Specification 3.6.1.6, and revises surveillance 4.6.1.6.1.e.l.

The AcrION Statement rewording assures acceptable design margins for the life of the plant. The revision to the surveillance eliminates the requirement for precise verification of the percent voids present in tendon sheathing filler grease. A conplete Safety Evaluation and Significant Hazards Consideration are provided as Attachments I and III respectively.

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ADOCK 05000482 PDR 201 N. Market -Wduta, Kansas - Mail Address: RO. Box 208 I Wichita, Kansas 67201 - Telephone: Area Code (316) 261-6451 L

.6.r. H.R. Denton KMLNRC 85-264 Page 2 Decenber 6, 1985 In accordance with 10 CFR 50.91, a copy of this application, with Attachments is being provided to the designated Kansas State Official. Enclosed is a check for the $150.00 application fee required by 10 CPR 170.21.

If you have any glestions concerning this matter, please contact ne or Mr. O.L. Maynard of my staff.

Very truly yours, W

Glenn L. Koester Vice President - Nuclear G M:see Enclosure Attachments: I -Safety Evaluation II -Initial Fill Void Factors III-Significant Hazards Consideration IV -Marked Tech. Spec, pages 3/4 6-8 and 3/4 6-9 cc: P0'Connor (2) w/a JCummins w/a G ulen w/a FJohnson w/a l

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Glenn L. Koester, of lawful age, being first duly sworn upon oath says that he is Vice President - Wclear and an Officer of Kansas Gas and Electric Conpany; that he has read the foregoing document and knows the content thereof; that he has executed that same for and on behalf of said Conpany with full power and authority to do so; and that the facts therein stated are true and correct to the best of his knowledge, information and belief.

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'Glenn L. Koester Vice President - Nulcear SUBSCRIBED and sworn to before me this ([" day of M t, 1985.

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Mr. H.R. Denton Attachment I to KMIRRC 85-264 Page 1 of 3 SAFE'IY EVALUATION This anendment requests the rewording of ACTION b. and the addition of ACTIONS c. and d. to Specification 3.6.1.6 and the revision of surveillance Specification 4.6.1.6.1.e.l. The existing ACTION b.

requires that whenever any element of the tendon surveillance acceptance criteria is not satisfied, it be considered as evidence of abnormal degradation of the structural integrity of the Containment vessel requiring that the integrity be restored or that the plant be shutdown. The proposed amendment, however, would classify a failure to satisfy an element of the acceptance criteria as evidence of possible abnormal degradation and would permit an evaluation to be performed demonstrating the continued ability of the Containment Vessel Structure to perform its design function. The proposed amendment still provides pronpt action for the plant to be shutdown if the engineering evaluation does not denonstrate Containment integrity.

The addition of ACTION c. provides for timely evaluation and correction of those parameters which in thenselves do not indicate abnormal-degradation but which may allow future degradation if not corrected. This ACTION also provides a report to the Cocmission describing the condition and action taken.

The inclusion of an exemption from the provisions of Specification 3.0.4 by adding ACTION d. reduces the inpact on plant operation consistent with the allowable times contained in ACTION a. and ACTION b.

The revision to 4.6.1.6.1.e.1 changes the requirement to verify the operability of the sheathing filler grease by assuring that there are no voids in excess of 5% of the net duct volume to the requirement to assure that widespread grease leakage has not occurred. The tendons at Wolf Creek were initially greased between February and Septecber,1982, by Inryco using current industry standard filling procedures. These procedures did not require recording the amount of grease injected into each sheath nor did they require verificaton that there were less than 5% voids. At that time, Kansas Gas and Electric was conmitted to Reg.

Gilde 1.35, Rev. 2, which deals only with voids in the trunpet area and not in the entire sheath. Revision 4 of Westinghouse Standard Technical Specifications, from which Wolf Creek made its original submittal, makes no mention of void measurement. The only method to accurately determine voids in the grease which "could be indicative of leakage in the tendon-duct system" is to assume the sheath was

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Mr. H.R. Denton Attachment I to KMLNRC 85-264 Page 2 of 3 1

coupletely filled initially. Attachment II shows that even under

cptinum filling conditions. volds of approximately 15% could be expected after the initial filling operation using current filling techniques. Therefore, the requirement for verification of less than

5% voids in not meaningful for 21f Creek and should be deleted.

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, The filling technique required -to assure that the tendon sheaths are i

initially 100% full of filler grease involves repeated filling of the sheath and allowing of the grease to cool. This can lead to gasket i

failures and leakage of the grease due to grease expansion during the

! sunner months.

The Elf Creek first year tendon surveillance is scheduled to be 1

performed beginning in Decenter 1985. Uhder the current Technical

, Specification requirements of assuring no voids in excess of 5% of the net duct volume, it is necessary to regrease the tendons involved to i

determine the percentage of voids. This operation is considered to be ,

unnecessary in view of the arguments presented herein and 4= = = an

' unnecessary burden especially in view of the difficulty of punping grease during the winter months.

Prevention of corrosion of the tendons is assured by coating adequately the tendon wires and the anchorage cwp ents. The material used in.

! the 21f Creek post-tensioning system, Visconorust 2090 N ,

acconplishes its corrosion protection function by the filler material's affinity to adhere to steel structures, its -ability to enulsify any moisture in the system nullifying its rusting ability, and 1

by its resistance to moisture, mild acids, and alkalis. As long as i

sufficient grease has been introduced into the system to coat the wires and anchorages completely, corrosion protection is assured. Protection j

' is also afforded by each tendon wire being individally pre-coated with Anber 1601 prior to installation. The degree ,of filling the interstitial spaces, which conprise the. net duct volume, i directly related to the degree of coating which occursisand, not 1

consequently, is not of significant inportance as an indicator of

. operability of the sheathing filler material.

Test data from the Callaway Plant, which has the identical containment as W lf Creek, and other plants with longer operating history have failed to show any correlation between the amount of voids and tendon strength -failures.

Callaway, Results of the initial tendon surveillance at

~ which are discussed in Ohion Electric letters to the IRC, i UIJmC-1172 dated Septenber 12, 1985 and UIJEC-ll73 dated September 18, i 1985, show that tendons requiring net refill volumes of the filler material in excess of the acceptance criteria have not shown any j abnormal deterioration or degradation of strength. The lift-off forces L

for those tendons, as well as the other surveillance tendons, have been j found to fall within (or above) the predicted limits. Examination and testing of the individual wires at Callaway has revealed that there is I

Mr. H.R. Denton Attachment I to KMLNRC 85-264 Page 3 of 3 no eviden of corrosion and that the wire strength exceeds the mininum required ultimate strength throughout the wires. Examination of the filler material has shown virtually no change in the physical appearance or chemical properties. 'Ibst results indicate that the amount of chlorides, sulfides, nitrates, and moisture fall far below the maxinum allowed limits as specified by the manufacturer. Visual inspection of the different conponents of the anchorage system revealed proper coverage by the filler material with no signs of corrosion or presence of water.

In accordance with the reconnendations of Regulatory Guide 1.35, proposed Rev. 3, a visual examinati>n of the exterior surfaces of the containment will be made at the beginning of the surveillance to. detect areas of widespread cracking, spalling, or grease leakage.

Additionally, if the presence of significant voids in the grease coverage is detected during surveillance operations or during grease replacement, the tendons will be regreased.

Based on the above discussion, the first surveillance at Callaway, and the evaluation of results from other plants, this amendment to Technical Specification 3/4.6.1.6 will not adversely affect the structural integrity of the containment vessel nor will it endanger the health and safety of the general public. This amendnent does not involve significant safety hazard as discussed in Attachment III.

Mr. H.R. Denton Attachment II to KMLNRC 85-264 Page 1 of 1 INITIAL FILL VOID FAC'IORS Voids in the tendon sheathing may be attributed to a nunber of additive factors:

1) Visconorust 2090P-4 has a coefficient of expansion which yields an expansion of about 1% per every 20 F. Initial filling tenperatures of the filler material can average 160 F. Cold weather conditions can cool the filler material to 40 F, giving a contraction of 6% of the net duct volume.

2) Calculated voids between the wires which cor: prise the tendon bundle are aproximately 7% of the net duct volume. If during the initial filling operations the tendon bundle is cold (anbient tenperature of 65 F.) and, as the filler material is punped into the sheathing void, it solidifies on the surface of the tendon bundle, small voids will be left between the wires. As the filler material gradually heats the tendon bundle during tendon surveillance, it is likely that the voids between the wires allow migration of the filler s terial into the tendon bundle. In addition, this type of migration could also occur at other areas such as where tendons are in contact with the sheathing.

3) Characteristics of the initial filling method may induce air entraFaent into the filler material. Punping operations can introduce air into filler material and may add up to as noch as 2%

of the net duct volume. This void value could be higher for horizontal tendons due to the lower punping head used when conpared to the vertical tendons.

In sunmary, even under optinum filling conditions, voids of approximately 15% could be expected after the initial filling operations.

Mr. H.R. Denton Attachment III of KMLNRC 85-264 Page 1 of 2 SIGNIFICANT HAZARDS CONSIDERATION This amendment request revises AcrION b. and adds ACTION c. and d.

associated with Technical Specification 3.6.1.6, and revises surveillatce 4.6.1.6.1.e.l. The ACTION statement rewording assures that there are acceptable design margins for the life of the plant while eliminating the need to shutdown the plant or maintain the plant shutdown when it can be shown by an engineering evaluation that the nonconforming parameters do not degrade containment integrity. The revision to the surveillance eliminates the requirements for precise verification of a parameter that cannot be accurately determined and has adequate backup surveillance parameters to assure acceptable design margins are maintained throughout plant life.

The Safety Evaluation submitted with this application provides Kansas Gas and Electric's bases for concluding that the Wolf Creek Generating Station can be safely operated consistent with the revised action statement.

In evaluating the increase in probability or consequences of any previously analyzed accident, the following areas were considered:

1. Desion Conservat4am The Containment vessel post tensioning system is a passive element designed to provide a mininum level of pre-stress of 1.2 x the design accident pressure at the end of the 40 year design life of the plant. As such, there is a wide margin of safety at the beginning of_ the plant life which decreases to a mininum value of 1.2 at 40 years.

2. Surwillance Precuency Periodic tendon surveillances are required by Reg. Guide 1.35.

The first three surveillances occur at 1.0, 3.0 and 5.0 years after the structural integrity test, and surveillances are required every five years thereafter. The length of the intervening period of 5 years between successive surveillances is evidence of the recognition of the extreme inprobability of the deterioration of the post tensioning system to a level where vessel integrity would be affected in this time period. As such, there is not basis for the requirement for restoration or shutdown within the time periods given in the Technical Specification.

3. Surveillance Results During the initial inservice tendon surveillance at the Callaway Plant, it was discovered that net refill volumes of sheathing filler material (grease) exceeded 5 percent of the net duct volume

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Mr. H.R. Denton Attachment III to P:MLNRC 85-264 Pay 2 of 2 for several tendons. These results for the affected tendons suggest that those tendon sheaths were not totally filled with grease, due to the initial fill void factors discussed in Attachment II and since volume control techniques were not used (or required) during initial filling.

The above incidences, involving net refill grease volumes in excess of the acceptance criteria, did not affect the strength of the Callaway tendons. Lift-off forces for the surveilled tendons were found to lie within (or above) predicted limits indicating that, among other things, wire integrity was not degraded.

Examination and testing of individual wires from the tendons revealed that there was no evidence of wire corrosion and that wire strength was not degraded. Examination of the grease itself revealed that there were no changes in the presence (at the anchorage) or physical appearance of the grease and the chemical properties were verified by laboratory analysis. As evidenced by examination of the surveillance tendons, the detected underfill conditions did not affect the ability of the grease to provide minimum coverage for the different parts of the anchorage system.

Additionally, data gathered from other plants with more operating history than Callaway have failed to show any correlation between percent voids and lift-off force or tensile strength failures.

Based on the above discussions, this change does not involvu a significant increase in the probability or consequences of an accident previously evaluated.

The propsed change to the Specification: will not inpact tendon integrity since tendon integrity will be assured by surveillance of remaining parameters and restoration of parameters or assurance by engineering evaluation; ~ will not affect the method and manner of plant operation; and will not affect conponents and equipment inportant to l safe operation. Therefore, the proposed amendment does not create the possibility of a new and different accident from any previously evaluated.

The surveillances and actions requested provide assurance that any tendon degradation would be identified and corrected in a timely manner consistent with the indicators, and, therefore, this change does not involve any reduction in a margin of safety.

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