ML20106C016

Revised marked-up Tech Spec 4.6.1.6.1,allowing Addl Time to Complete Containment Vessel Tendon Surveillances

ML20106C016
Person / Time
Site:	Callaway
Issue date:	02/08/1985
From:	UNION ELECTRIC CO.
To:
Shared Package
ML20106C009	List: ML20106C006 ML20106C016
References
NUDOCS 8502120118
Download: ML20106C016 (1)

Text

bAEk.YN* '4.; : Ob.-....qAMQ:wp.9+:Sh%h Y h* * . -;? ? . ,,;&ie.d W. n &bd -

= '

~ * ~

, x. y ;a , . ;.*y /;;y:~3

y. ay, ..

p.z ,; .'.y3 314 554 3550 02/07/85 14:37 RX1. EAR SERVICES NO.011 001

.~ .

Enclosure 1 to ULNRC-1037 l

SAFETY EVALUATION This amendment request revises the timing associated with Technical Specification Surveillance 4.6.1.6.1, by extending the containment vessel tendon surveillances by a stop change of six (6) months. This extension is required for the initial callaway inspection because INRYCO, a common inspection contractor to Union Electric and Alabama Power Co., is needed to evaluate anomalies found at the Parley - Unit 2 plant, prior to performing inspections at Callaway. The following sections address the Callaway post tensioning system design conservatism, inspections of installation activities, field anchor head materials, recent field inspection results, and expected results of the initial tendon surveillance based on Bechtel experience.

Design Conservatism The containment vessel post tensioning system is designed to provide a minimum level of prestress of 1.2 times the design accident pressure at the end of the 40-year design life of the plant. The prestressing tendons are initially stressed to provide an even higher level of prestress to allow for time dependent stress losses which occur during the life of the plant.

As such, there is a significantly higher level of prestress provided at the beginning of the design life than at the end.

The Callaway post tensioning system was designed for an internal containment pressure of 72 design accident pressure of 60 psig.psig, In the which event is 1.2 of atimes the postulated main steam line break (yields the maximum containment pressure), the maximum pressure will be only 48.1 psig, however. -

This provides an actual margin of 1.31 instead of the required value of 1.2. When the prestressing levels which are predicted to occur in approximately six months from.now are also taken into account, the margin becomes approximately 1.43.

It should be noted that the required level of prestress of 1.2 times the accident pressure is provided only to maintain compression in the concrete shell during the SIT. This level of prestrese is not required, however, to maintain structural integrity.

The containment was designed to remain elastic up to internal pressures of approximately 90 psig and it can be shown that the ultimate capacity is at least 120 psig.

_ Inspections of Installation Activities  !

During the period of February 1981 through October 1981, the following audits, surveillances and inspections were completed as a result of witnessing the installation of the Callaway containment post tensioning system by INRYCO. )

8502120110 850200 l PDR ADOCK 05000483 l p PDR l l - - 1

.m - 1

W & & g.= 2p~i %>s.m%%%hl

- +. *- .

w :w:a

~ q'g S.4llrk;1&*;6%ziM w 4,+. . .%e,pWQW 9g,y; 02/07/85 14:37 MILEAR SERVICES to.011 002 1 -

Bechtel/UEQA Audit d -

CEQA Surveillances 1 -

DIC/UEQA Audit 3 -

DIC/QA surveillances 7 -

NRC Inspection Reports These reports document the performance of tendon button heading, tendon stressing, greasing, material storage, equipment calibration / qualification, QC inspection, and personnel qualification. These reports indicate satisfactory performance of in=tallation of the callaway post tensioning system by INRYCO.

UEQA Surveillance Report 4/81-11 documents measures taken by INRYCO to assure that anchorhead failures which occurred in other plants in the past will not occur at callaway.

Field Anchor Head Materials A sampling review of the records provided by INRYCO on the Callaway anchor head steel manufacturers and heat treatment vendors showed the following:

Steel Manufacturer Manufacturing Dates Copperweld 1980, 81 Tech. Steel & Alloy 1979, 80 Timken 1976, 80 Heat Treatment Vendors Procedure Used Varco Heat Division MIL-H-6875-F Accurate Steel Treating INRYCO PT 5.2.1 FPM Heating Division INRYCO PT 5.2.1 -

The use of the Military specification used'by Varco was approved by Bechtel via SDDR No. 10.

Problems encountered with cracking anchor heads at othe:: job sites were found to be with different steel msnufacturers and heat treatment vendors and manufactured in the early 1970's. In addition, INRYCO attributed as one of the possible causes for cracking to be the nickel content. As a result of this, INRYCO revised their specification to limit the nickel content to a maximum of 0.25% (Surveillance Report 4/81-11) . The records reviewed showed that in all cases the callaway anchor heads have nickel content below 0.25%.

Based on the above it would appear that the anchor heads used at Callaway are acceptable based on the fact that Callaway had different manufacturers and material analyses that were involved with anchor head failures at other sites.

- - . . ..h .._ _ _ . . _

.Nf. *hl. .

• I. EY

. l l f~'* : 5 "jY.

. '**? fj. ME*Q .:

02/Er7/95 14:38 14.lCLENt SERVICES 10.011 003 1

l l

Recent Field Inspection Results On February 5, 1985 a visual inspection of the Callaway containment post tensioning system was conducted by personnel from Union Electric engineering and operations maintenance departmentu and Bechtel field engineering. The inspection involved looking for tendon grease cap deformation or grease leakage and excessive cracking around the tendon bearing plates.

Further visual inspection cannot be performed without removing the grease cap, which requires the services of INRYCO to re-instate to operable status.

A close inspection was made of 172 (86 tendons) inverted U and 100 (50 tendons) hoop anchorages. No deformation, excessive grease leakage or cracking was found.

An inspection of the remaining 170 (85 tendons) hoep.and 60 (30 tendons) horizontal dome anchorages was made with the aid of field gicsses. No deformation or excessive grease leakage was found.

Based on this inspection of all Callaway tendon anchorages, no evidence was found to indicate a tendon failure nor. evidence to indicate excessive stress in the concrete.

Bechtel Initial Tendon Surveillance Experience Bechtel has designed 14 units which employ post tensioning system and have completed the first year inspections. Four of

' these units involved INRYCO, the same supplier as was used at -

Callaway. All surveillances were acceptable.

{ Conclusion '

[

l Based on the information above, the proposed revision to Technical Specification 4.6.1.6.1 does not affect or endanger the health and safety of the general public and does not involve an -

l unreviewed safety question.

t i

l l

i p .. _ _ - * .

I.".((2b !N '[ . . h..; f.. .

v-f 4 N. 1

? - -9l

.u .,;; - $N .

~ .g.m bNIPk g..y.. ps N?

y' . , -

. . -l.; .

>.m

. , ' J-. ,. .

7 w 2 w . ~;::: y a.y' .; ;

5.'_j k.'J.7 M "'?5$ y y ,i l .

}.g .. C~.y . , j. . ' 7.. 3,j.

- 1: ~ V. .- . . ,

02/07/85 14:38 MJCLEMt SERVICES 10.011 004 Enclosure 2 to ULNRC-1037 SIGNIFICANT HAZARDS CONSIDERATIONS This amendment request revises the timing associated with Technical Specification Surveillance 4.6.1.6, by extending the

' containment vessel tendon surveillances by a step change of six (6) months. The Safety Evaluation, included as Enclosure 1 to this letter, provides Union Electric's bases for concluding that the Callaway Plant can be safely operated consistent with the revised surveillance schedule.

The Commission has provided guidance concerning the application of the standards in 10CFR50.92 by providing certain examples (48 FR 14870). This amendment request is not completely analogous but is most similar to the example of an action involving no significant hazards consideration which relates to a change which either may result in some increase to the consequences of a previously - analyzed accident or may reduce in some way a safety margin, but where the results of the change are clearly within all acceptable criteria with respect to the system or component specified in the Standard Review Plan. However, based on the Safety Evaluation, we do not believe the increase in the initial surveillance interval in any discernible way increases the consequences or reduces the safety margin associated with the containment post tensioning system.

This amendment request does not involve a significant increase in the probability or consequence of an accident or

, other adverse condition over previous evaluationst or create the possibility of a new or different kind of accident or condition  !

reduction in a margin of safety. Based on this information, the l requested license amendment does not present a significant

• l hazard.

..a e-w *- /*al/ "y- lU* '

s ? * *

• Wl ' . * * * * *. . ' - * - - .

1. s *

• de.4.[q. . ..*J; &' ..'. ,. :,:-4,: a n.'&..m. Q .'4 . p .:,, u T- Q = = b.: , Ch- ?, . , 'y 5%.n ,

. *p.:;' . s Ud..

~ G.

?5* ,

.}' f .. .,y-lf y_" Q

.Vf. .? l,,(.'l y-2 T.f. 6y. .

, 4 gyl4../.

f .g.  ; y d[4 - . ,. a . ,. .g-yg 'i . --

m' ,Q,.$gg

r. . . .g _ . , . . . . ,,. N, . y, 314 554 3550 t,:0NI AINM!.N1 Vl ut t SflitlCIURAt INICCW!!Y

~

. l_tMifING CON 01 TION 10R OPERATION

't . G .1. 6 The structural integrity of the containment vessel shall be maintained

.it .i level consistent with the acceptance criteria in Specification 4.6.1.6.

AP,tlCAutiIlY:

p MODES 1, 2, 3, and 4.

fg:

a. With more than one tendon with an observed lif t-off force between the predicted lower limit and 90% of the predicted lower ifmit or with one tendon below 90% of the predicted lower limit, restore the twndon(s) to the required level of integrity wi. thin 15 days and perform an engineering evaluation of the containment and provide a Special Report to the Commission within 30 days in accordance with Specif icat.iun 6.9.2 or be in at least HOT STANDSY within the next G hours and in COLD SHUT 00WN within the following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />.

h. With any abnormal degradation of the structural integrity other than ACTION a. at a level below the acceptance criteria of Specifica-tion 4.6.1.6, restore the containment vessel 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 ul the containment and provide a Special Report to the Commission within 15 days in accordance with Specification 6.9.2 or be in at least NOT STANOBY 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 SHUTDOWN .v .

within the following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />.

SURVI.llt.ANCE REQUIREMENTS e

~ f.f 3.3 3 4.6.1.G.1 Contain1hent. Vessel Tendons. Thecontainmehtvssel endons' struc-tur.il int.egrity shall be demonstrated at the end of E, ' , and,Ir" years following the init.ial cuntainment vessel structural integrity test and at 5 year intervals there.sf ter. the tendons' structural integrity shall be demonstrated by: *

a. lietermining that, a random but representative sample of at least 11

• l tendons (4 inverted U and 7 hoop) each have-an observed lift-off i l

lurce within predicted limits for each. l'or each subsequent inspec- l l t inn one Lention from each group may be kept unch'anged to develop a _,

l History and to correlate the observed data. If the observed lift off lorce of any one tendon in the original sample population lies In' tween the predicte I lower limit and 90% of the predicted lower j limit, two tr!ndons, one un each side of this tendon shnold be checkec .I

f or t heir li f t-ni f fnrces. 'll both~of these adjacent. tendent. are l inunti t.n be within their predicteil limits, all three tendons should lu* re.tored to t,he required level of integrity. This. single acticiency l m.iy in' t.inisinered unique and acceptable. Unless there is abnormal eli'ilr.idation of the containment vessel during the first three inspec-tions. the sample population for subsequent inspections shall include a t. least 6 tendens (3 inverted U and 3 hoop);

b CAtt AWAY - UNil 1 3/4 6-8 1

t

~

~

~

-w -

om -