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           '                                                                                                                                                                                    I NRC Poans see
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: u. s. NUCLE A2 KEcutATcRv Commission tr m                                                    Update Report - Previous Report Date 6/30/80                                                                                        {
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43              44              47 CAUSE DESCRimCN AND CORRECTIVE ACTIONS @
43              44              47 CAUSE DESCRimCN AND CORRECTIVE ACTIONS @
l i l o i 1 A review of the original load calculations revealed loadine deficiencies. We have                                                                                        l g l received revised load calculations from Westinghouse and all embedment capabilities ;
l i l o i 1 A review of the original load calculations revealed loadine deficiencies. We have                                                                                        l g l received revised load calculations from Westinghouse and all embedment capabilities ;
                                                                                                                                                                                          ;
i l exceed the maximum imposed load.
i l exceed the maximum imposed load.
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: 30. ;
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NAME OP PREPARER
NAME OP PREPARER


_ _ _ _
    .
      .
Attachment To LER 80-44/01T-1 Beaver Valley Power Station Duquesne Light Company Docket No. 50-334 During a recent review of the original calculations for the steam generator lower snubber embedments, it was determined that the design calculations did not reflect the condition of the embedments as shown on the construction drawing. The original calculation assumed that the load was applied to an infinite wall normal to the wall surface, rather than skewed. Furthermore, the original calculations were based on loads specified in FSAR Volume 4, Table 5.2-3, which were subsequently incteased due to the effects of seismic loads and loads associated with asymetric pressurization of the reactor cavity due to a break at the RPV outlet nozzle.
Attachment To LER 80-44/01T-1 Beaver Valley Power Station Duquesne Light Company Docket No. 50-334 During a recent review of the original calculations for the steam generator lower snubber embedments, it was determined that the design calculations did not reflect the condition of the embedments as shown on the construction drawing. The original calculation assumed that the load was applied to an infinite wall normal to the wall surface, rather than skewed. Furthermore, the original calculations were based on loads specified in FSAR Volume 4, Table 5.2-3, which were subsequently incteased due to the effects of seismic loads and loads associated with asymetric pressurization of the reactor cavity due to a break at the RPV outlet nozzle.
When an analysis was e.de considering the "as-installed" configuration, the increased loadings, and the original design strength of concrete, i.e. 3,000 psi in accordance with Section 1707 of ACI 318-63* Code, it was found that the embedment exceeded the design allowables in peripheral shear. The following is the summary of the actions taken to resolve this issue.
When an analysis was e.de considering the "as-installed" configuration, the increased loadings, and the original design strength of concrete, i.e. 3,000 psi in accordance with Section 1707 of ACI 318-63* Code, it was found that the embedment exceeded the design allowables in peripheral shear. The following is the summary of the actions taken to resolve this issue.
Line 80: Line 65:
: 3. An analysis taking into account the overall loads on the embedment and the              l in-place strength of the concrete has been performed. As the steam generator snubbers are attached to the walls at an angle, the pullout force on the                l embedment was resolved into two components, one tensile component normal to            l the wall and the other shear component parallel to the face of the wall.                I This was done only as a mathematical tool, and the basis of the assumption              l 1s that if the peripheral shear capacity of the embedment is more than the              ;
: 3. An analysis taking into account the overall loads on the embedment and the              l in-place strength of the concrete has been performed. As the steam generator snubbers are attached to the walls at an angle, the pullout force on the                l embedment was resolved into two components, one tensile component normal to            l the wall and the other shear component parallel to the face of the wall.                I This was done only as a mathematical tool, and the basis of the assumption              l 1s that if the peripheral shear capacity of the embedment is more than the              ;
tensile component normal to the face of the wall, the.embedment is adequate            ;
tensile component normal to the face of the wall, the.embedment is adequate            ;
for the pullout force, as the shear component will not adversely affect the resistance of the concrete in the normal direction.      The wall (structure)          l was analyzed using Section 1707 of ACI 318-63 Code, utilizing a 0 factor of 0.85 and assuming a peripheral shear mode of failure.                                  i
for the pullout force, as the shear component will not adversely affect the resistance of the concrete in the normal direction.      The wall (structure)          l was analyzed using Section 1707 of ACI 318-63 Code, utilizing a 0 factor of 0.85 and assuming a peripheral shear mode of failure.                                  i l
                                                                                                  !
1 l
l 1
1 l
l 1
l


  .
e t.ttachment To LER 80-44/OlT                              Beaver Valley Power Station Duquesne Light Company Docket No. 50-334
e
                                                                              .
                                                            '
t.ttachment To LER 80-44/OlT                              Beaver Valley Power Station Duquesne Light Company Docket No. 50-334
: 4. The results of this analysis provide a factor of safety for these embedments which varies from 1.28 to 2.7 (as compared to a code requirement of 1.0) depending on magnitu'de of loading and geometry of the six embedments. The contribution from the reinforcing steel and the effcets of proximity to the adjoining supports have not been taken into account, and the analysis is therefore, considered to be conservative. It should be noted that as a further conservatism, no increase in concrete stress allowable was considered due to the dynamic nature of the load.
: 4. The results of this analysis provide a factor of safety for these embedments which varies from 1.28 to 2.7 (as compared to a code requirement of 1.0) depending on magnitu'de of loading and geometry of the six embedments. The contribution from the reinforcing steel and the effcets of proximity to the adjoining supports have not been taken into account, and the analysis is therefore, considered to be conservative. It should be noted that as a further conservatism, no increase in concrete stress allowable was considered due to the dynamic nature of the load.
: 5. In connection with this review, we have also reevaluated the internal support structure under snubber loads combined with other appropriate loads.
: 5. In connection with this review, we have also reevaluated the internal support structure under snubber loads combined with other appropriate loads.
This evaluation demonstrates that the structure is capable of carrying all applicable loads.
This evaluation demonstrates that the structure is capable of carrying all applicable loads.
     . Based upon the above evaluation, we conclude that the steam generator lower embedments are adequate to perform their intended function.
     . Based upon the above evaluation, we conclude that the steam generator lower embedments are adequate to perform their intended function.
                                                                              .
e e
e
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                                                                .
                                                                                            .'
                                                                                          .
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                                                                                               .}}
                                                                                               .}}

Latest revision as of 10:45, 18 February 2020

Updated LER 80-044/01T-1:on 800630,during Recent Review of Original Calculations for Steam Generators,Lower Snubber Embedments Conditons Found Inconsistent W/Design Specs. Caused by Loading Deficiencies
ML19338F106
Person / Time
Site: Beaver Valley
Issue date: 09/30/1980
From: Lacey W
DUQUESNE LIGHT CO.
To:
NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML19338F098 List:
References
LER-80-044-01T, LER-80-44-1T, NUDOCS 8010070526
Download: ML19338F106 (2)
v • d • e


Text

.

' I NRC Poans see

u. s. NUCLE A2 KEcutATcRv Commission tr m Update Report - Previous Report Date 6/30/80 {

LICENSEE EVENT REPORT CONTRot stoCx: l l l l l l l (Pt.EAsa PRINT OR TYPf ALL REQutRED INFORMATIONI i e@

@ l 4P9 l A lUCENSig B l VCooE l S l 1 l@l 0 l 01- l 0WCEN5ENumetR 10 l 0 l 0 l 0 l- l0 l 0 l@l4 4S 2A l1 WCENSEl1 l1 Typel 1aJ l@l l

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8 le it CON'T RTTl O',"c!IL @lol 5101010131314 l@l016 tad 69 f 31018 tvtNT cATg I o @l o I o IREPORT to 15 3 I ooATE f a l 01@ 80 I 4 to el coCKETNUMSER EVENT DESCRim0N AND PROSA8LE CONSECuENCE5 h roTT1 o i A review of the orie.inal calculations for the steam generator lower snubber l (TTTl I embedments showed that the design calculations did not reflect the "as constructed" [

ITT71 I condition of the embedments. Attached is a summarv of the actions taken to resolve l

^

g ithis issue. This analysis provided a safety factor for all the embedments greater l o e I than the ende recuirement: therefore, there were no consecuences to this event. l I

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43 44 47 CAUSE DESCRimCN AND CORRECTIVE ACTIONS @

l i l o i 1 A review of the original load calculations revealed loadine deficiencies. We have l g l received revised load calculations from Westinghouse and all embedment capabilities ;

i l exceed the maximum imposed load.

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. . acey PHONE.

~ ~

NAME OP PREPARER

Attachment To LER 80-44/01T-1 Beaver Valley Power Station Duquesne Light Company Docket No. 50-334 During a recent review of the original calculations for the steam generator lower snubber embedments, it was determined that the design calculations did not reflect the condition of the embedments as shown on the construction drawing. The original calculation assumed that the load was applied to an infinite wall normal to the wall surface, rather than skewed. Furthermore, the original calculations were based on loads specified in FSAR Volume 4, Table 5.2-3, which were subsequently incteased due to the effects of seismic loads and loads associated with asymetric pressurization of the reactor cavity due to a break at the RPV outlet nozzle.

When an analysis was e.de considering the "as-installed" configuration, the increased loadings, and the original design strength of concrete, i.e. 3,000 psi in accordance with Section 1707 of ACI 318-63* Code, it was found that the embedment exceeded the design allowables in peripheral shear. The following is the summary of the actions taken to resolve this issue.

1. The increased lower snubber embedment loads described above were compared with loads for similar embedments for Beaver Valley Unit 2 and other similar plants. It was found that Beaver Valley Unit 1 loads are much higher than other newer stations and, therefore, Westinghouse was contracted to generate revised loop forcing functions for a break at the RPV outlet nozzle based on latest analytical techniques. Using the revised Westinghouse forcing functions, the BVPS Unit 1 architect-engineer (Stone & Webster) developed a new set of loads to be applied to the steam generator lower snubber embedments, including the seismic and asymetrical pressure effects. The overall loads on the steam generator lower snubber embedm'ents are louer than the original loads specified in the FSAR by approximately 100 to 180 k-ps (10 to 12 percent).

~

2. Due to the presence of fly ash in the design concrete mix and the age of the concrete, the present in-place strength of concrete in the embedment walls is much higher than the original design strength of 3,000 psi. By using Windsor probles which were correlated with strength of concrete cores, an evaluation in accordance with ACI 214-77 has been completed of the in-place concrete strength of the snubber embedment area which indicates the present compressive strength of in-place concrete to be 5,560 psi.
3. An analysis taking into account the overall loads on the embedment and the l in-place strength of the concrete has been performed. As the steam generator snubbers are attached to the walls at an angle, the pullout force on the l embedment was resolved into two components, one tensile component normal to l the wall and the other shear component parallel to the face of the wall. I This was done only as a mathematical tool, and the basis of the assumption l 1s that if the peripheral shear capacity of the embedment is more than the  ;

tensile component normal to the face of the wall, the.embedment is adequate  ;

for the pullout force, as the shear component will not adversely affect the resistance of the concrete in the normal direction. The wall (structure) l was analyzed using Section 1707 of ACI 318-63 Code, utilizing a 0 factor of 0.85 and assuming a peripheral shear mode of failure. i l

1 l

1 l

e t.ttachment To LER 80-44/OlT Beaver Valley Power Station Duquesne Light Company Docket No. 50-334

4. The results of this analysis provide a factor of safety for these embedments which varies from 1.28 to 2.7 (as compared to a code requirement of 1.0) depending on magnitu'de of loading and geometry of the six embedments. The contribution from the reinforcing steel and the effcets of proximity to the adjoining supports have not been taken into account, and the analysis is therefore, considered to be conservative. It should be noted that as a further conservatism, no increase in concrete stress allowable was considered due to the dynamic nature of the load.
5. In connection with this review, we have also reevaluated the internal support structure under snubber loads combined with other appropriate loads.

This evaluation demonstrates that the structure is capable of carrying all applicable loads.

. Based upon the above evaluation, we conclude that the steam generator lower embedments are adequate to perform their intended function.

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.

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