ML20081L757

Proposed Tech Specs Re Containment Tendon Surveillance Requirements

ML20081L757
Person / Time
Site:	Fort Calhoun
Issue date:	06/28/1991
From:	OMAHA PUBLIC POWER DISTRICT
To:
Shared Package
ML20081L752	List: ML20081L750 ML20081L755 ML20081L757
References
NUDOCS 9107080050
Download: ML20081L757 (23)

Text

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, e ATTACHMENT A l

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t 9107080050 910623 PDR ADOCK 03000283 P PDR

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' 3.0 CURVEILLANCE REQUIREMENTS 3.5 Containment Test _s,(Continued)

(7) Surveillance for Prestressino System I a.\ ' urveillance Reouirements

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Two hundred ten dome tendons and 616 wall tendons shal b\ periodically inspected for '.ymptoms of material de rioration or force reduction. Inspections wili ce per rmed on three dome tendonss one from each layer, and o three wall tendons of each orier tation.

The surv illance tendons shall be inspected as follows:

(i) Lif off readings shall be taken on each of the tendo s selected to determine.the load exitting in the te on at the time of inspection. At s ch surveil nce period, readings may also be taken on the load ells of the special instrumented tendons. '

Force redu tions on the surveillance tendons and on the instrum ted tendons will be compdred. If good correlation e ists between these two grcups of tencens thrcugh severa surveillance periods, consideration will be given t eliminating some lift-off readings and monitoring o the load cellt as an alternative.

Each selected tend shall be completely detensioned and examined for bro, en wires and any evidence of damage or deteriorati of anchorage hardware.

(ii) One wire from each of th ee helical tendons and one wire of a dome tendon sha 1 be removed. Each removed wire shall be carefully ex ined over its entire length for evider.ce of corro 1on or other deleterious effects. . Tensile tests shall e made on it least three samples cut from each of the f5r wires. removed, one at each end ard one at midlength of a maximum length practical esting. fo\r tne In samples special being cases, the use of fatigie tests an accelerated cerrosion tests may be_considerfd.

(iii) Comparisons shall be made between the q ality control records and each of the surveillance ins ction records for each of the surv0illance tend s.

After. completion of the tendon surveillance the ind idual detensioned tendons shall be retensioned to a force mmen-surate with the average wire stress indicated by the 1 At lif t-off reading for that tendon. \

3-45 Amenoment t o. 95,g7

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3. 0 SURVEILLANCE RE0VIREMENT5 3.5 Containment Tests (Cont 1,nuec) l

o. 3ccectance Criteris (i The tencon force cetermined by the lift-off test snail be cons 1 cerea adeouate if it is not less than :ne farce snown on tne anpropriate lower limit curve of USAR igure 5.10-3, as adjustea for wire removal, for tne aosed time between the original prestressing anc ne pa ticular surveillance period. These icwer limit cur es have oeen generated by calculating the difference betw n the anticipated tenacn force at end of plant life d the minimum tendon force to meet the cesign recuire eats. One nalf of this difference nas been added to the anticipated total loss of prestreet at tne ena of pl t life and the curves nave been arawn to meet this imit. Since the lock-off force on incivicual tencons is ried to compensata for elastic snortening of the struct re, the tendon force at 70% of ultimate strength, rath r than the actual lock-off force snail b6 tak6n as the initial prestress force. An allowaole limit of not mor than one defective tencon out of the total samole popul tion is acceptacle, providee an adjacent tencon on ach side of the cefective tencon is tested and is found meet criteria. Should one of the aajacent tencons also founa defective, the Commission snall be not'fied in accorcance with Regula-tory Guice 1.16, " Report g of Operating Information" (ii) No unexpected change in co osion conditions or grease properties.

(iii) All three tensile tests on any ne wire indicate an l

ultimate strength at least equa to the specifiea i minimum ultimate strength of the girc. If a single test on any one wire shows an ultir ate strengtn less l

than the specified minimum, the Co ission will be i

l notified in accordance with Regulato Guide .16, l "Recorting of Operacing Information".

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c. CorrectiveAgjoz If the acove acceptance criteria are rot niet, an i .meaiate investigation snall be made to determine the cause( ) for the non-conformance to the criteria, and results will be ecorted i to the Commission within 90 days.

d. Test Frecuency The tendons in the prestressing s tem s snall be inscisctEc l

ance every 5 years.

3-46 Amenament No. 35.97, 119 l

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4 3.0 SURVEILLANCE REQUIREMENTS 3.5 Containment Tests (continued)  :

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. I 3-47 Amenoment No. 95, 97 .

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. 3.0 SURVEILLANCE REQUIREMENTS 3.5 Containment Tests (continued) i DELETED ,

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N 3-48 Amendnx.iit No. $$. gy R

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te e 3.0 SURVEILLANCE RE0VIREMENTS +

3.5 Containment-Tests (Continued) 4 k -

l Basis The containment is designed for an accident pressure of 60 psig.(2) While the reactor is operating, the internal environment of the containment will be air at approximately atmospheric pressure and a maximum temperature of about 120*F. With these initial conditions the temperature of the steam-air mixture at the peak' accident pressure of 60 psig _is 288'F.-

Prior to initial operation, the containment was strength-tested at 69 psig and then was leak tested. The design objective of the pre-operational leakage rate test has been established as 0.1% by weight for 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> at 60 psig. This.leakege rate is consistent with the construction of the containment, which is equipped with independent leak-testable penetrations and contains channels over all. inaccessible containment liner welds, which 1 were. independently leak-tested during construction.

- Safety analyses have been performed on the- basis of a leakage rat'e of 0.1%

of the free volume par day of the first 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> following the maximum hypothetical accident. With this leakage rate, a reacter power level of- '

1500 MWt, and with minimum' containment engineered safety systems for iodine removal in operation (one air cooling and filtering unit), the public exposure -

would be well belo 10 CFR Part 100 values in.the event of the maximum hypo-thetical accident. 3) .The performance of a periodic integrated leakage rat 2 i

3-49 Amendment No. d$' 97 l

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3.0 SURVEILLANCE REQUIREMENTS 3.5 Containment Tests (Continued) test during plant life provides a current assessment of potential leakage frnm the containment.

The reduced pressure (5 psig) test on the PAL is a conservative method-of testing and provides adequate indication of any potential contain-ment leakage path. The test is conducted by pressurizing between two resilient seals on each door. The test pressure tends to unseat the resilient seals which is opposite to the accident pressure that tends to seat the resilient seals. The six nionth test ensures the overall PAL int'egritv at 60 psig.

The frequency of the periodic integrated leakage rate test (Type A test) is keyed to the refueling schedule for the reactor, because this test can only be performed during refueling snutdowns.

The specified frequency of periodic integrated leakage rate tests is based on three major consioerations. First is the low prcbability of leaks in the liner because of sie rest of the leak-tightness of the welds during erectica and _ conformance of the complete containment to a low leak rate at 60 psig during pre-operational testing, which is consistent with 0.1" leakage at design basis accident conditions and absence of any significant stresses in the liner during reactor opera-tion. Second is the more frequent testing, at the full accident pressure, of those portions of the containment envelope tnat are most likely to develoo leaks curing reactor operation (penetrations and isolation valves) and tne low value (0.60J of the total leakace that is specified as acceptacle from penetrations and isolation valves. --La-l Third is the tendon stress surveillance program, which provides assurance tnat an important part of the structural integrity of the containnent is maintained.

Integrity tests of the purge isolation valves are established .to identify excessive degracation of the resilient seats of these valves.

Simultaneous testing of redundant purge valves from a leak test connection accessible frcm outside-containment provides adequate testing. The testing method is identical to the Type C purge isola-tion valve test performed in accordance with 10 CFR Part 50, Appendix J. For leakages found to be greater than 18,000 SCCM, repairs'shall be initiated to ensure these valves meet the acceptance criteria.

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3-50 Amendment No. 2J,63,95

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3.0 SURVEILLANCE REOUIREMENTS 3.5 Containment Tests (continued) .

A reduction in prestressing force and changes in physical conditions are expected for the prestressing system. Allowances _have been made in the reactor-building design for the reduction and changes. -Me-nowen wn ...u.6, .m m .. -...... ...i' 50 re:Orded er the #0-r

vided for th:t perpe:: :nd compariser "i be made "itn the previcus t::t rc; ult: :r.d th: O iti:1 qu:lity centre' record .

" r --time tr:nd l'ne: 41' :!:0 be : tab!!:hed and :f-taf aed 'er

-:::P Of the :urvef'leace teadcas.

+ e force-time trend line, as extrapolated, falls below the predi o force-time curve for one or more surveillance tendons, then before next scheduled surveillance inspection, an inves-tigation shall de to determine whether the rate of-force reduction is indeed o ring for other tendons. If the rate of rectetion is confirmed, tn vestigation shall be extended so as to identify the cause of the ra f force reduction. The exten-sion of the investigation shall dete ... the needed changes in the surveillance inspection schedule and riteria and initial Planning for corrective action. If the force-t trend lines of

• the surveillance tendons at any time exceed the uppe 'nd curve

' of the band on the force-time graph, an investigation sha e made to determine t..e cause.

{ Through comparisons between the documented inspection results and the initial quality control records, the reductions in prestress and the physical changes are trended to verify excessive reductions- or changes -

do not occur or are detected in a timely manner to be corrected.

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3-51 Amendment No. $8, 97

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3.0 SURVEILLANCE REQUIREMENTS 1.5 Containment Tests (Continued) arison of the corrosion conditions, including chem. cal tests of the c s4cn_grotection material, indicates larger than expected change in the con 16 '

the time of installation or last surveillance inspection, an investi -tie -

11 be made to detect and correct the causes.

(prestressingj The prestressing system is a necessary strength element of the plant safeguards and it is considered desirable to confirm that the allowances are not being exceeded. The technicas chosen for surveillcnce is based upon the rate of change of ffi.ce and physical conditions so that the surveillance can either confirm that the allowances are sufficient or require maintenance before minimum

{ prestressingl levels off force or physical conditions are reached. The end anchorage concrete is needed to maintain the prestressing forces.

The design investigations ha/e concluded that the design is adequate and thj.s has- been confirmed by tests, The prestressing sequence has shown that the end anchorage concrete can withstand loads in e.vcess of those which result when the tendons are anchored.

Further, the containment building was pressure tested to 1.15 times the maximum design pressure.

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3-52 Amendment No. 97 9

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. 3.0 SURVEILLANCE REQUIREMENTS t

3.5 Containment Tests (Continued)

Referenc.:s, s

(1) USAR, Section 5.9A-(2) USAR, Section 5.1.1 (3) USAR, Section 14.15 l

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l 3-53 M.endment ::o 95 l l-

3.0 SURVEILLANCE REOUIREMENTS 3.5 Containment Tests (Continued)

(7) Surveillance for Prestressing System

a. Sample Selection The 210 dome tendons and 616 helical wall tendons shall be periodically inspected for symptoms of material deterioration or prestressing force reduction.

Inspections shall be performed on four dome tendons, one from each layer and the control dome tendon, and ten helical wall tendons, five of each orientation including one control tendon in each orientation.

The tendons to be inspected shall be randomly selected from the tendons which have not been tested in previous surveillances, except for the control tendons which shall be included in each surveillance sample selection to develop a historical trend in order to correlate the observed data,

b. Visual Inspection The following visual inspections shall be performed:

(i) The exterior surface of the containment shall be visually examined to detect areas of large spall, severe scaling, D-cracking in areas of 25 square feet or more, grease-leakage, and other significant structural deterioration or disintegration.

(ii) For each surveillance tendon, selected in accordance with 3.5(7)a., the tendon anchorage assembly hardware shall be visually inspected for signs of abnormal material behavior or wear.

(iii) The concrete surroundmg tiie visually inspected tendon anchorages shall be visually inspected for signs of significant structural deterioration.

(iv) The bottom grease caps of all helical wall tendons shall be visually inspected to detect grease leakage or grease cap deformations, Removal of the grease caps is.not necessary for this inspection.

c. Prestress Monitoring Tests i

Liftoff tests shall be performed on each tendon selected in accordance with 3.5(7)a. to monitor prestress. Additionally, the tests shall include the following:

3-45 Amendment No. 95-97

s 3.0 SURVEILLANCE REOUIREMENTS 3.5 Containment Telts (Continued)

(i) Two helical wall tendons, one of each orientation, and one dome tendon, each randomly selected from their respective groups of surveillance tendons, shall be detensioned and inspected for broken or damaged wires.

The control tendons shall NOT be included as tendons to be detensioned.

(ii) During retensioning, simultaneous elongation and jackir g force measurements shall be made at a minimum of three approximately equally spaced levels of force between zero and the lock-off force. The two intermediate stress levels shall be as near as practical to the values shown on the initial stressing records for the respective tendon,

d. Tendon Material Tests and Insnections One wire from och of two helical wall tendons, one of each orientation, and one dome tendon, shall be removed for the following tests and examinations:

(i) Each removed wire shall be examined over its entire length for any evidence of corrosion or other deterioration.

(ii) Tensile tests shall tu made on at least three samp!cs of each wire, one cut from each end and one cut from midlength. The samples shall be the maximum length practical for testing and the guage length for elongation shall be in accordance with ASTM E8 " Standard Test Methods for Tension Testing of Metallic Materials." The following information shall be obtained from each test:

(a) Yield Strength, (b) Ultimate tensile strength, and (c) Elongation at ultimate tensile strength.

3-46 Amendment No. 95;97;149 i

3.0 SURVEILLANCE REOUIREMENTS 3.5 Containment Tests (Continued)

The tendons detensioned in accordance with 3.5(7)c.(i) may be the tendons from which the sample wires are temoved. The control tendons shall NOT be included as tendons to be detensioned or have wires removed.

In addition, all wires found to be broken shall be removed for tensile testing and visual examination.

e. Insocction of Filler Grease A sample of sheathing filler grease from each of the sample tendons shall be taken and analyzed according to the following national standards:

(i) To determine water content, ASTM D95, " Standard Test Methods for Water in Petroleum Products and Bituminous Materials by Distillation."

(ii) To determine reserve alkalinity, ASTM D974, " Standard Test Method for Acid and Base Number by Color-Indicator Titration."

(iii) To determine the concentration of water soluble chlorides, ASTM D512,

" Standard Test Methods for Chloride Ion in Water."

(iv) To determine the concentration of water soluble nitrates, ASTM D3867,

" Standard Test Methods for Nitrite-Nitrate in Water."

(v) To determine the concentration of water soluble sulfides; APHA 4500 S 2.

D. " Methylene Blee Method, Standard Methods for Examination of Water and Waste Water. Seventeenth Editi on.

In addition to these tests, the amount of filler grease mouved f rom and replaced into each surveillance tendon shall be recorded and compared to assess grease leakage within the containment structure,

f. Accentance Criteria (i) No evidence of significant structunl deterioration of the concrete .

inspected in accordance with 3.5(7)b.(i) and 3.5(7)b.(iii) which may affect the structural integrity of the containment structure can be detected.

c. 3-47 Amendment No. 95,9-7

o 3.0 SURVElLLANCE REOUIREMENTS 3.5 Containment Tests (Continued)

Significant structural deterioration is defined as measurable structural deterioration which, when compared v ith past inspections, shows strong evidence of an increase of structural deterioration which could affect the.

Containment's structural integrity. Evidence of cc,smetic or superficial deterioration, unless determined by sound engineering judgement to be significant, is not considered to be significant structural deterioration.

No evidence of significant material degradation or corrosion of tendon anchorage hardware can be detected.

If any grease leakage is detected during visual examination of the containment exterior surface, an investigation shall be made to determine the extent of potential reduction of Containtnent structural integrity. An investigation shell also be made to determine which tendons could have lost the grease and whether the grease loss has adversely affected their corrosion protection.

(ii) The prestressing force measured for each tendon liftoff tested in accordance with 3.5(7)c. shall be compared with the limits predicted by USAR Fig 5.10-3. If the measured prestressing force of a selected tendon is greater than the prescribed lower limit, the tendon is acceptable.

If the measared prestressing force of a selected tendon is less than .the prescribed lower limit but greater than or equal to 95% of the prescribed lower lim t,i the tendon shall be tensioned :o a prestress value greater than the prescribed lower limit but less than 742 kips. After increasing the tendon's prestress the tendon will be considered acceptable.

3-48 Amendment No. 95,9-7 I

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l 3.0 SURVEILLANCE REOUIREMENTS l 3.5 Containment Tests (Continued)

If the measured prestressing force of a selected tendon is less than 95%

of the prescribed lower limit but greater than or equal to 90% of se prescribed lower limit, two additional tendons, one on each side of the first tendon, shall be liftoff 1.sted. If the prestressing forces of each of the second and third tendons are greater than 95% of the prescribed lower limit, all three tendons shall be tensioned to greater than the prescribed lower limit, but less than 742 kips. After increasing the tendons' prestress, the tendons will be considered acceptable. If the prestressing force of either the second or third tendcas is less than 95% of the presc.ibed lower limit, liftoff tests shall be performed on additional tendons to determine the cause and extent of such occurrence. This occurrence shall be considered reportable per 3.5(7)g, If the measured prestressing force of a selected tendon is less than 90% of the prescribed lower limit, the defective tendon shall be fully inspected to determine the cause and extent of such occurrence. This occurrence shall be considered reportable per 3.5(7)g.

If the average prestressing force of all measured tendons of a group (corrected for average condition) is found to be less than the prescribed lower limit, an investigation shall be performed to determine the cause and extent of such an occurrence. Such an occurrence shall be coasidered reportable per 3.5(7)g.

If from consecutive surveillances the average measured prestressing force of a tendon group trends at a rate which would indicate that the loss of prestress would make the average prestress of the group of tendons less than the prescribed lower limit before the nnt surveillance, additional i

liftoff tests shall be performed to determine the cause and extent of such occurrence. Such an occurrence shall be considered reportable per 3.5(7)g.

(iii) If during the detensioning and retensioning of tendons in accordance with 3.5(7)c., the elongation corresponding to a specific load differs by more than 10% from that recorded during installation ci the tendons, an iavestigation shall be made to ensure that the difference is not related to wire failures or slippage of wires in anchorages. A difference of more than 10% shall be considered reportable per 3.5(7)g.

s 3-49 Amendment No. 95,97 1

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l 3.0 SURVEILLANCE REOUIREMENTS 3.5 Containment Tests (Continued)

(iv) The minimum acceptable ultimate tensile strength of the wire samples to be tensile tested shall be 240,000 psi with a miniinum elongation of 4% in accordance with ASTM A421-65 for Type BA wire. Failure in the tensile test at strength or elongation values less than those specified shall be considered repoitable per 3.5(7)g.

Other conditions which indicate corrosion found by visual examination of the wire shall be considered reportable par 3.5(7)g.

(v) Results of the laboratory tests and examinations of the filler grease will be considered acceptable if the following conditions are met:

(a) Water content i 10% by weight (b) Chlorides i 10 ppm (c) Nitrates i 10 ppm (d) Sulfides i 10 ppm (e) Reserve alkalinity >0 l (' Base numbers)

(f) The difference between the amount.of grease injected into a tendon to replace the amount which was removed during inspection shall not exceed 5% of the net tendon sheath

-(duct) volume-when injected at the original installation pressure.

l (g) The lack of the presence of any free water.

The failure to meet any of the above conditions for the filler grease shall be considered reportable per 3.5(7)g.

(g) Corrective Action and Rgp0niDE If the above acceptance criteria are not met, an immediate investigation shall be made to determine the catise(s) and extent of the non-conformance '

to the criteria, and the resu'ts shall tse reponed to the Commissio.n within 90 days via a special report in accordance with Technical Specification 5.9.3.

l 3-50 Amendment No. 24,68 795

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3.0 SURVEILLANCS Rb 'IREMENTS 3.5 Containment Tests (Contmued)

(h) Test Frequency The tendon prestressing system surveillance shall be performed once every 5 years.

Basis The containment is designed for an accident pressure of 60 psig.* While -

the reactor is operating, the internal environment of the containment will be air at approximately atmospheric pressure and a maximum temperature of about 120'F. With these initial conditions the temperature of the steam-air mixture at the peak accident pressure of 60 psig is 288 F.

Prior to initial operation, the containment was strength-tested at 69 psig and then was leak tested. The design objective of the pre-operational leakage rate test has been established as 0.1% by weight for 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> at 60 psig. This leakage rate is consistent with de construction of the containment, which is equipped with independent leak-testable penetidens and contains channels over all inaccessible containment liner welds, which were independently leak-tested during construction.

Safety analyses have been performed on the t uis 6f wleaka e a.0 of 0.1% of the free volume per day of the firr '4 Eue Wbwing the maximum hypcthetical accident. With this less  % uctor 1,ower level of 1500 MWt, and with min'.num cowinn.ient engiNered safety systems for iodine removal in operation L e dr ccding and filtering unit), the public exposure would be well bmw 10 CFX Part 100 values in the event of the maximum hypothmics. acciaent m The performance of a periodic integrated leakage rate h > , Wom iiie povides a current assessment of potential lege tro.. toe containment.

The reduced pressure (5 psig ::st u the PAL is a conservative method of testing and provides adeqt. . 'ndication of any potential containment leakage path. The test is conducted by pressurizing between two resilient seals on each door. The test pressure tends to unseat the resilient seals which is opposite to the accident pressure that tends to seat the resilient seals. The six month test ensures the overall PAL integrity at 60 psig.

The frequency of the periodic integrated leakage rate test (Type A test) is keyed to the refueling schedule for the reactor, bwause this test can only be performed during refueling shutdowns.

3-51 Amendment No. 68,97

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3,0 SURVEILLANCE REOUIREMENTS 3.5 Containment Tests (continued)

The specificd frequency of periodic integrated leakage rate tests is based on three major considerations. First is the low probability of leaks in the liner because of the test of the leak-tightness of the welds during erection and conformance of the complete containment to a low leak rate at 60 psig during pre-operational testing, which is consistent with 0.1% leakage at design basis accident conditions and absence of any significant stresses in the liner during reactor operation. Second is the more frequent testing, >

at the full accident pressure, of those portions of the containment envelope that are most likely to develop leaks during reactor operation (penetrations and isolation valves) and the low value (0.60L.) of the total leakage that l is specified as acceptable from penetrations and isolation valves. Third is the tendon stress surveillance program, which provides assurance that an '.aportant part of the Fructural integrity of the containment is maintained.

Integrity tes of the purge isolation valves are established to identify excessive degradation of the resilient seats of these valves. Simulta icous testing of redundant purge valves from a leak test connection accessible from outside containment provides adequate testing. The testing method is identical to the Type C purge isolation valve test performed in accordance with 10 CFR Part 50, Appendix J. For leakages found to be greater than 18,000 SCCM, repairs shall be initiated to ensure these valves meet the acceptance criteria.

A reduction in prestressing force and changes in physical conditions are expected for the prestressing system. Allowances have been made in the reactor building design for the reduction and changes. Through comparisons between the documented inspection results and the initial quality control records, the reductions in prestress and the physical

changes are trended to verify excessive reductions or changes do not occur or are detected in a timely manner to be corrected.

i 3-52 Amendment No. 9'l

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s 3.0 SURVElLLANCE REOUIREMENTS 3.5 ContainmenLTssis (continued)

The prestressing system-is a necessary strength element of the plant safeguards and it is desirable to confirm that the allowances are not being -

exceeded. The technique chosen for surveillance is based on the rate of change of prestressing force and physical conditions so that the j surveillance can either confirm that the allowances are sufficient or require maintenance before minimum levels of prestressing force or physical conditions are reached. The end anchorage concrete is needed to main the prestressing forces. The design investigations have concluded that the design is adequate and this has been confirmed by tests. The prestressing sequence has shown that the end anchorage concrete can withstand loads in excess of those which result when the tendons are anchored. Further, the containment building was pressure tested to 1.15 times the maximum design pressure.

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.Referenegs (1) USAR, Section 5.9 l

(2) USAR, Setion 5.1.1 (3) USAR, Section 14.15 3-53 Amendment No. 95

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Discussion and Justification The Omaha Public Power District proposes to change Technical Specification 3.5(7) to adopt the guidance of NRC Regulatory Guide 1.35, Revision 3, July 1990, for the maintenance of the Prestressing System Surveillance Program.

I The current specification was written to comply with the guidance of NRC Regulatory Guide 1.35, Revision 1 June 1974. It requires the inspection of three dome tendons and three helical wall tendons of each orientation at a five year frequency. The inspection is to include liftoff force measurements for each selected tendon, complete detensioning of all selected tendons to inspect for broken wires and any evidence of damage or deterioration of the anchorage hardware, and the removal of one wire from each of one dome tendon and three wall tendons for examination and tensile testing. It also requires a comparison be made between the quality control records and each of the surveillance inspection i records for each of the surveillance tendons.

The proposed change to the specification would require the inspection of four dome tendons and five helical wall tendons of each orientation at a five year frequency. The inspections would include liftoff force measurements for each selected tendon, complete detensioning of one dome tendon and one helical wall tendon of each orientation to inspect for broken wiros and any evidence of damage or deterioration of the anchorage hardware, and the removal of one wire from each of one dome tendon and one helical wall tendon of each orientation for examination and tensile testing. The new specification would require the

laboratory testing of samples of filler grease from each tendon to determine water content, reserve alkalinity, and the cc'icentrations of water soluble

, chlorides, nitrates and sulfides. It would also require the estimation of grease

, leakage from each selected tendon by measuring the difference between the amount of grease removed from a tendon and the amount of grease required to refill the

, tenden. These tests and examinations are recommended by Reg Guide 1.35, Revision l 3.

! Fort Calhoun Station's Containment Prestressing System is configured dif ferently than the configuration described in Reg Guide 1.35, Revision 3, Regulatory Position C.2. The wall endoas mentioned in Regulatory Position C.2. include l hoop and vertical tendons. The wall tendons an fort Calhoun Station are left-i hand and right-hand oriented helical wall tenduns. Each orientation will be considered as a separate group.

l The current Specli1 cation _has these three acceptance criteria:

i. The tendon force determined by the lif toff test shall be considered adequate if it is not less than the force sh;wn on the appropriate lower limit curve of USAR Figure 5.10- for wire removal, for the elapsed time between the[3), as adjustec original prentressing and the particular surveillance period... An allowable limit of not mere than one defective tendon out of the total sample population is acceptable, provided an adjacent tendon on each. side of the defective tendon is tested and is found to meet criteria.

ii. No unexpected change in the corrosion conditions or grease properties, iii. All three tensile tests on any one wire indicate an ultimate strength at least equal to the specified minimum ultimate strength of the wire.

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Discussion and Justification (continued)

If any of the above acceptance criteria are not met, an imediate investigation shall be made to determine the cause(s) for the non-confermance to the criteria, and results will be reported to the Commission [NRC) within 90 days. (Tech Spec paragraphs 3.5(7)b. &

3.5(7)c.)

The proposed change would incorporate acceptance criteria similar to those specified in Reg Guide 1.35 Revision 3. To prevent the ovar stressing of tendons tha proposed change would limit any corrective increas6 of a tendon lock-off stress to greater than the lower limit but less than 0.7 Ultimate Tensile Strength (UTS) or 742 kips.

The Commission has expressed its desired format for a prestressing system surveillance program in its Regulat.ory Guide 1.35, Revision 3, issued July 1990.

The proposed change incorporates that format and would improve the surveillance program by requiring the visual inspection of the concrete and anchorages, the analysis of the protective filler grease, and the use of control tendons to establish an ongoing history. It would also reduce the burden by eliminating Justification of the costly, unnecessary changes to Technicaldetensionings of the tendons. Specification Surveillance Requirement 3 and the Regulatory Guide 1.35, Revision 3, are contained in NUREG/CR-2719, Evaluation of Jnservice Ins _pection o' Greased PresidLsjjna Tendons s and in NUREG/CR-4712, Reaulatory Analysis of Reaulatory Guide 1.35 (Revision 3. Draft 2) "In-Service Inspection of Unarouted Tendons in Prestressed Concrete Containments".

Administrative Changes l

Page 3-52 The allowable leakage rate symbol L, is added to the discussion on i

its value.

Page 3-53 Reference 1 is revised from b.9.1 to 5.9.

Bases of No Significant Hazards Consideratio 3 Will the proposed change involve a significant increase in the probability or consequences of an accident previously evaluated?

I I No. The prestressing system was designed to be tested and inspected. The l activities required by the proposed change do not add any new stresses to the containment structure and the increase in sample size will not adversely af fect any tendons since the tendons are designed to be tested in the manner prescribed. In the unlikely event that a design basis LOCA occurs during the performance of a prestressing system surveillance and one of the tendons is detensioned, sufficient prestress would still be applied to the containment concrete according to USAR Section 5.3.3, which stated, The design of the containment satisfies the criteria of [USAR Sections] 5.5.1, 5.5.2.2, 5.5.2.3, and 5.5.2.4 with sufficient margin to compensate for the loss of approximately five to ten wall tendnns and two to three dome tendons depending on their location and spacing relative to each other.

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Bases of No Significant Hazards Consideratics (cc..!!.wed) j Will the change create the possibility -of a new or different kind of accident from any accident previously evaluated?

No. The prestressing system doe's ' not interf ace with ary active systems of the station. -The prestressing system was designed to be tested and inspected. Thereforo, this change will not create the possibility of a new or different nind of accident from any accident previously evaluated.

Will the change involve a significant reduction in a margin of safety.

No. The ch n ge does not alter any testing practices in a way which would comprt...ise containment structural integrity. The relaxation of the requirement to detension all selected tendons to detensioning one-tendon per group increases.the margin of safety by reducing the probability of prestressing tendon assembly degradation by component dismantling and reassembling. This shouTd provide increased assurance of the overall margin of safety designed into the containment structure.

The Commission has provided guidance concerning the application of the standards for determining whether a significant hazards consideration of amendments that are exists by providing considered not likely certain toexamples involve significant (48 FR 14870) hazards ' consideration.

Example-(ii relates to a change that constitutes additional controls not presently co)ntained in the Technical Specifications.

I The proposed change described above is similar to Example (ii) in that the

-proposed changas will adopt surveillance,requiraments stated in Regulatory Guide 1.35 Revision 3.

Therefore based on the above considerations, 0 PPD does not.believe that this proposed amendment involves a significant- hazards consideration as-defined by 10 CFR 50.92 and 'the proposed changes -will not result in a cor.dition which significantly -alters the impact of- the Station on the +

environment. Thus, the pro 30 sed change meets the plio categorical exclusion-set forth in -16 CFR 51.22(e)(f)ibility and pur:;uant criteria to for 10 CFR 51.22(b)' no environmental assessment need be-prepared.

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