ML17268A221
| ML17268A221 | |
| Person / Time | |
|---|---|
| Site: | Fort Calhoun  |
| Issue date: | 09/25/2017 |
| From: | Fisher M Omaha Public Power District |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| LlC-17-0059 | |
| Download: ML17268A221 (20) | |
Text
Omaha Public Power District Ll C-17 -0059 September 25, 2017 U.S. Nuclear Regulatory Commission Attn : Document Control Desk Washington, DC 20555-0001 Fort Calhoun Station (FCS), Unit 1 Renewed Facility Operating License No. DPR-40 NRC Docket No. 50-285
Subject:
Response to Request for Additional Information (RAI) Regarding License Amendment Request 16-04 Revising Current Licensing Basis to Use ACI Ultimate Strength Requirements Fort Calhoun Station, Unit 1 Docket No.: 50-285
References:
- 1. Letter from Omaha Public Power District (S. M. Marik) to NRC (Document Control Desk), "License Amendment Request (LAR) 16-04; Revise Current Licensing Basis to Use ACI Ultimate Strength Requirements" dated October 25, 2016 (LIC-16-0093)
- 2. EMAIL from NRC (J. Kim) to OPPD (E. P. Matzke), "Final RAI for Fort Calhoun Ultimate Strength Design for Aux. Bldg LAR (MF8525)", dated July 13, 2017 (ML17194A973)
By letter dated October 25, 2016 (Reference 1), the Omaha Public Power District (OPPD) proposed an amendment to Renewed Facility Operating License No. DPR-40 for the Fort Calhoun Station (FCS). The proposed amendment would revise the FCS Updated Safety Analysis Report (USAR) to change the structural design methodology for the Auxiliary Building at FCS. Specifically, this LAR proposes the following changes:
- 1. Use the ultimate strength design (USD) method from the ACI 318-63 Code for normal operating/service conditions for future designs and evaluations.
- 2. Use higher concrete compressive strength values for Class B concrete based on original strength test data.
- 3. Use higher reinforcing steel yield strength values based on original strength test data.
- 4. Minor clarifications include adding a definition of control fluids to the dead load sections.
On July 13, 2017 (Reference 2), the NRC provided OPPD with Requests for Additional Information (RAI) regarding the proposed changes . Enclosure 1 of this letter provides the responses to the RAI.
U.S. Nuclear Regulatory Commission LIC-17-0059 Page 2 to this letter contains a revision to section 2.2 of the LAR (Reference 1). Enclosures 3 and 4 provide updated markups of the affected sections of the Final Safety Analysis Report as Updated.
This change to the LAR has been reviewed and approved by the station's plant operations review committee (PORC). This letter contains no regulatory commitments.
If you should have any questions regarding this submittal or require additional information, please contact Mr. Bradley H. Blome, Director- Licensing and Regulatory Assurance at (402) 533-7270.
I declare under penalty of perjury that the foregoing is true and correct. Executed on September 25, 2017.
Mary J. Fisher Senior Director - Decommissioning Fort Calhoun Station MJF/epm
Enclosures:
- 1. Response to Request for Additional Information
- 2. LAR 16-04 Revised Section 2.2
- 3. Revised affected USAR Section 5.11.3 (Mark-Up)
- 4. Revised affected USAR Section 5.11.3 (Clean) c: K. M. Kennedy, NRC Regional Administrator, Region IV J. Kim, NRC Project Manager R. S. Browder, NRC Senior Health Physicist, Region IV Director of Consumer Health Services, Department of Regulation and Licensure, Nebraska Health and Human Services, State of Nebraska
LIC-17 -0059 Page 1 ENCLOSURE 1 REQUEST FOR ADDITIONAL INFORMATION (RAI) REGARDING LICENSE AMENDMENT REQUEST 16-04: REVISING CURRENT LICENSING BASIS TO USE ACI ULTIMATE STRENGTH REQUIREMENTS OMAHA PUBLIC POWER DISTRICT FORT CALHOUN STATION, UNIT 1 DOCKET NO.: 50-285 On June 28,2017, the U.S. Nuclear Regulatory Commission (NRC) staff sent Fort Calhoun Station (FCS) the draft Request for Additional Information (RAI). This RAI relates to the amendment to revise Updated Safety Analysis Report {USAR) to change the structural design methodology for the Auxiliary Building at FCS. On July 13, 2017, a teleconference between FCS and NRC staff was held to discuss the information requested by the NRC staff was understood and any additional clarifications on the RAI were required. Based on the teleconference, FCS determined that the information requested by the NRC staff was clearly understood and any other additional clarifications on the RAI was not necessary. FCS agreed to provide a response to this final RAI shown below by September 29, 2017. The NRC staff also informed the licensee that a publicly available version of this final RAI would be placed in the NRC's Agencywide Documents Access and Management System.
Structural Engineering Branch (ESEB)- RAI 1
Background:
Table 1 in Section 2.1.1 of the LAR (Reference 1) notes that ACI 318-63 is the current licensing basis (CLB) design code of record for Fort Calhoun Station (FCS). The CLB requires the use of working stress design (WSD) method for normal service conditions, and ultimate strength design {USD) method for no loss-of-function and special load cases. The LAR proposes to revise the CLB to use the USD method from ACI 318-63 for normal service load conditions for future design and evaluation of the Auxiliary Building. Section 4.2 of the LAR notes that several operating nuclear power plants constructed in the era that FCS was built use the ACI 318-63 USD method for normal operating/service load combinations.
Class 1 concrete structures, including earlier-vintage plants that have adapted ACI 318-63 or ACI 318-71 as the licensing basis code-of-record, have typically been licensed to load combinations {normal operating/service condition and extreme (no loss of function and special cases) condition) with load factors associated with design loads in the combination based on the NRC staff position documented in NUREG-0800 Standard Review Plan (SRP) 3.8.4 and Regulatory Guide (RG) 1.142 (which currently endorses ACI 349-97 with conditions). The factor assigned to each load in a load combination is influenced by the degree of accuracy to which the load effect can be calculated, the variation expected in the load during the life of the structure, the probability of simultaneous occurrence, and assumptions and approximations in the structural analysis calculations.
LIC-17 -0059 Page 2 Issue:
The second and third load combinations (associated with footnote (2) in LAR Table 5) use the existing USAR USD equations for the no loss-of-function condition (extreme condition) and modify the equation by replacing the differential pressure component with the live load, and the differential temperature component with the soil load. The LAR notes that the resulting equation is "similar" to ACI 318-71 equation 9-2 (the load factors are not the same as equation 9-2). It is unclear to the staff why it is appropriate to modify in this fashion the loads in existing USD equations for extreme load conditions to develop load factors for the proposed USD service load combinations. It is also unclear why it is appropriate to selectively choose numerically inconsistent load factors from later editions of ACI318 without reconciling the other related code provisions, and/or existing NRC staff positions in the SRP and RG 1.142.
The LAR notes that other operating nuclear plants use the ACI 318-63 USD method for normal operating/service load conditions; however, the LAR does not cite specific precedent where the NRC has previously approved the load factors for USD service load combinations proposed in Table 5 of the LAR. The NRC staff is not aware of past precedent that used the proposed load factors.
Request:
Provide technical justification for the proposed load factors associated with USD service load combinations in the second and third equations (associated with footnote 2) in LAR Table 5 (i.e., justify acceptability of substituting service loads into an equation associated with unusual or extreme load conditions).
If the response discusses ACI 318-71 equation 9-2 clearly explain why it is appropriate to selectively use load factors from three different codes in the proposed USAR (ACI 318-63, ACI 318-71, and ACI 349-97) without reconciliation with other related code provisions or an existing staff position.
If the response basis relies on precedent based on operating nuclear power plants that used ACI 318-63 USD service load combinations, provide details identifying previous case history and explain how the proposed load factors for the second and third USD service load combinations in FCS's LAR is consistent with that of the precedent plant OPPD Response to ESEB - RAI 1 To address NRC's comments regarding the acceptability of substituting service loads into an equation associated with unusual or extreme load conditions and to eliminate the perception of selectively using load factors from three different codes (ACI 318-63 [1], ACI 318-71 [2], and ACI 349-97 [3]), the licensee is proposing a revision to Section 2.2 to replace the original ACI 318-63 Working Stress Design (WSD) methods for operating/service load conditions with ACI318-63 Ultimate Strength Design (USD) methods in combination with ACI 318-71 service condition factored load combinations. In other words, ultimate strengths of structural members calculated in accordance with ACI 318-63 USD methods along with the equivalent factored load combinations as defined in ACI 318-71 will be used .
LIC-17-0059 Page 3 To show the generic relationship between the ACI 318-63 WSD load combinations and the ACI 318-71 USD load combinations, a derivation is provided in Attachment A of this RAI response.
As derived, the equations (RAI Eqn. 3 and RAI Eqn. 4) in Attachment A are the same as equations 2 and 3 of the revised LAR Section 2.2 (see Enclosure 2) except the load factor forD, which is 1.05 per ACI318-71, Eqn. (9-2) instead of 1.27 as derived, and ct> which is required since U in the LAR is nominal ultimate strength.
This response to the NRC's RAI does not rely on precedent from any operating nuclear power plants that used ACI 318-63 USD service load combinations.
This proposed change will apply load factors from ACI 318-71 to the equivalent load combinations listed in the revised USAR Section 5.11.3.4 for operating conditions. Currently, USAR Section 5.11.3.4 specifies the working stress method for Operating Basis Load Combinations. This is different than USAR Section 5.11.3.5 that specifies the ultimate strength method from ACI 318-63 for no-loss-of-function load combinations, which include tornado wind, maximum hypothetical earthquake, differential pressure, soil pressure, and maximum flood loads. This change will promote a consistent implementation of calculations by permitting a uniform design methodology for the re-evaluation of the Auxiliary Building at Fort Calhoun Station.
Comparison of LAR to NUREG-0800 Standard Review Plan (SRP) 3.8.4 Per note 1 on page 13 of SRP 3.8.4 [6], the one-third increase in allowable stress for concrete and steel due to seismic or wind loadings is not permitted for WSD. So, the wind load factor derived in Attachment A becomes 1.69 (i.e., 1.333*1.27). 1.69 is essentially the same as 1. 7 wind load factor in load combination b.3 on page 9 of SRP 3.8.4. The seismic load factor derived becomes 1.9 (i.e., 1.333*1.4). The load factor for OBE seismic load in load combination b.2 on page 9 of SRP 3.8.4 is also 1.9.
SRP 3.8.4 references ACI 349 as the applicable code. To remain consistent with code years applicable to SRP 3.8.4, Regulatory Guide (RG) 1.142 [9] endorses the use of ACI 349-76 [8] for design of nuclear safety related concrete structures. As shown in Section 9.3.1 of ACI 349-76, as augmented by RG 1.142, the load factors for both wind and OBE seismic loads are the same as those listed within SRP 3.8.4.
Since concrete structures at FCS were designed per ACI 318-63, which allows one-third increase in allowable stresses (long before SRP 3.8.4 was first issued) the wind and seismic load factors from ACI 318-71 are considered more appropriate for a plant of FCS's vintage. It is important to point out that differences in wind and seismic load factors between ACI 318-71 and SRP 3.8.4 are due to different allowable stresses permitted for WSD load combinations involving wind and seismic loads as proved by the derivation in Attachment A.
Comparison of LAR to ACI 349-97 Regulatory Guide (RG) 1.142 [7] endorses ACI 349-97 for design of nuclear safety related concrete structures. As shown in Section 9.2.1 of ACI 349-97, the load factors for both wind and OBE seismic loads are 1.7.
L1 C-17 -0059 Page 4 The wind load factor derived in Attachment A is 1.69 (i.e., 1.333*1.27). 1.69 is essentially the same as 1. 7 for wind and OBE seismic loads required by ACI 349-97. Larger wind and seismic load factors in AC! 349-97 are due to the one-third increase in allowable stresses is not permitted in ACI 349-97. The increase in allowable stresses is permitted by ACI 318-63 for WSD load combinations involving wind and seismic loads.
Since concrete structures at FCS were designed per ACI 318-63, which allows one-third increase in allowable stresses, long before ACI 349-97 was first issued, the wind and seismic load factors from ACI 318-71 are considered more appropriate for a plant of FCS's vintage.
References:
- 1. ACI318-63, American Concrete Institute (ACI) standard building code requirements for reinforced concrete
- 2. ACI318-71 , ACI standard building code requirements for reinforced concrete
- 3. ACI 349-97, Code Requirements for Nuclear Safety Related Concrete Structures
- 4. Letter from Omaha Public Power District (S. M. Marik) to NRC (Document Control Desk),
"License Amendment Request (LAR) 16-04; Revise Current Licensing Basis to Use ACI Ultimate Strength Requirements" dated October 25, 2016 (LIC 16 0093) (ML16299A275)
- 5. Michael R. Lindeburg, Civil Engineering Reference Manual, 5th Edition
- 6. NUREG-0800 Standard Review Plan (SRP) 3.8.4, Rev. 1
- 7. Regulatory Guide (RG) 1.142, Safety-Related Concrete Structures for Nuclear Power Plants (Other than Reactor Vessels and Containments), Rev. 2
- 8. ACI 349-76, Code Requirements for Nuclear Safety Related Concrete Structures
- 9. Regulatory Guide (RG) 1.142, Safety-Related Concrete Structures for Nuclear Power Plants (Other than Reactor Vessels and Containments), Rev. 1 Attachment A. ACI 318-63 WSD I ACI 318-71 USD Derivation
L1 C-17 -0059 , Attachment A Page 1 ENCLOSURE 1 ATTACHMENT A ACI 318-63 WSD I ACI 318-71 USD Derivation Derivation of Wind Load Factor In the current license basis, the WSD load combination involving wind load is, S = D + L + W + H, where Sis the required section strength Section 1004 of ACI 318-63 allows 33-1/3 percent increase in allowable stresses for members subject to stresses produced by wind or earthquake forces combined with other loads. So, allowable bending moment for sections governed by reinforcement is, S =As{1 .333fs)*jd
- Where, As = steel area fs = allowable steel stress, which is 20 ksi for 40 ksi reinforcement per ACI 318-63 Section 1003 d = distance from extreme compression fiber to centroid of tension rebar j = moment arm factor, which is the distance between centroids of concrete compression block and tension rebar when multiplied by d Per ACI 318-63 Eqn. (16-1 ), ultimate bending strength for sections governed by steel is, U= 0.9*Asf/(d-a/2)
- Where, fy = Yield strength of steel, which is 40 ksi for 40 ksi reinforcement d= distance from extreme compression fiber to centroid of tension rebar a = depth of concrete block s 1.333Asfs
- jd 0.74j
u 0.9A sf y *d(l - ~) 1- -
a 2d 2d
LIC-17-0059 , Attachment A Page 2 Per step 1 in Section 8.G of Chapter 14 of Reference 5, a general rule used to design economical beams is to satisfy the following equation, (RAI Eqn. 1) where p and .( are reinforcement ratio and compressive strength of concrete, respectively. RAI Eqn. 1 corresponds to half of the maximum allowable reinforcement ratio Pmax = 1/2*(0.75* Pbatance ) ,
i.e. 0.375 P batance , where P balance is balanced reinforcement ratio. Neutral axis at balance dbatance measured from the extreme compression fiber is, d b l E d& d£s E c 87000d
~ d = = = 0.685d (RAI Eqn. 2) aaozce d - d balance =E-c s
balance Es c
+ Ec E s &s + E s E c Jy + 87000 =
Where Es = Young's Modulus of steel, which is 29000000 psi 8s = Yield strain of steel E
c
= 0.003, which is the maximum strain of concrete at ultimate strength Esec = 87000 psi Whenp = 0.375pbalance , a = {3 1 (0.375* dbalance) = 0.85*0.375*0.685d = 0.218d
( /3 1 , as defined in ACI 318-63 USD, is equal to 0 .85 for 4000 psi concrete)
As shown by the Mathcad calculation on the following page, j = 0.948. So, s 0.74*0.948 u= 0.21 8 = 0.787 s = 0.787U 1- - -
2 S = 0.787U = 0 + L + W + H ~ U = 1.270 + 1.27L + 1.27W + 1.27H (RAI Eqn. 3)
Equation 2 in Section 2.2 of the LAR is U = ~ cp (1.05D + 1.275L + 1.275W + 1.275H), which is effectively the same as RAI Eqn. 3, except the load factor for 0, which is 1.05 per ACI 318-71, Eqn. (9-2) instead of 1.27 derived above, and ct> which is required since U in the LAR is nominal ultimate strength.
LIC-17-0059 , Attachment A Page 3 Derivation of Seismic Load Factor Per ACI 318-71 Section 9.3.3, the USD load combination involving seismic load is obtained by substituting 1.1 E for W. By substituting 1.1 E for W in the load combination for wind derived above, we get, U = 1.270 + 1.27L + 1.27*1.1 E + 1.27H =1.270 + 1.27L + 1.4E + 1.27H (RAI Eqn . 4)
Equation 3 in Section 2.2 of the LAR is U =; (1.05D + 1.275L + 1.40£ + 1.275H), which is effectively the same as RAI Eqn. 4, except the load factor forD, which is 1.05 per ACI 318-71 ,
Eqn. (9-2) instead of 1.27 derived above, and ct> which is required since U in the LAR is nominal ultimate strength.
LIC-17-0059 , Attachment A Page 4 Mathcad Calculati on Concrete Compression Strength ~ f'c := 4000-psi Yield Stress of Steel IPer ACI 318, for normai 1Neight concrete Densit y of normal weight c o c1et.e: ,,, := il45-ibf (for calculating concrete modulus of elasticity}
Concrete Modulus of elasticity .
Modt.!lus of elasticity steel:
AC I-318 WORKING STRESS BEAM DE 51iG~N (Tria ngular Concrete Stress Block)
E5 Modular ratio: n -*= E ="I ..Q<i8 ~
c Concret e al~ owab! e compression stress :
Per Sect~ on 1003 of ACI 3"18 [1] "fur all other reinforcemernt" , allowable stress reinforcement is 20.000 psi
.n. **~-t'y -- ~")
4 Steel allowable tension stress : 1'*:; .- - lJI X 11-' -P-l For the balance condition. neutral ax~ s i:act or k is determined as follows in accordance with Appendix 8 t o Chapter 14 of Refe rence 5.
Neutral axis factor at ba~an ce : k := - - - = 0.4 1 f.,.,
-~- +1 n-f c
!' ~, l<il .
- - 1 '-'-~ ! -'"- _ n n "
Moment arm factor: J .- - -j- - v.;:o4,:;
LIC-17-0059 Page 1 ENCLOSURE 2 LAR 16-04 Revised Section 2.2 2.2 Use USD for Normal Operating/Service Conditions For normal operating/service conditions, ACI 318-63 USD method with factored load combinations defined in ACI318-71 is used . Ultimate strengths of structural members are calculated in accordance with ACI 318-63. The design loads are not changed; however, definitions of soil pressure (H) and controlled hydrostatic loads and their inclusion into load combinations are added to the USAR for better clarity of the design method.
The strength reduction factors (<t>) for use with USD in normal operating/service conditions remain consistent with those already accepted for use with USD in no loss-of-function loading conditions.
In normal operating/service conditions, the equivalent load combinations for USD (PLB) in comparison to WSD (CLB) are as follows:
Table 5- Load Combinations Ultimate Strength Design Working Stress Design (PLB) (CLB)
U =2:.(1.4D rp
+ 1.7L + 1.7H)< 1l S=D+H+L U =; (l.OSD + 1.275L + 1.27SW + 2 3 1.27SH)l X l '
S = D + L + H + W or E U = 2:.(1.05D rp
+ 1.275L + 1.40£ + 1.275H)<4 l( 5 l U = 2:. (1.4D + 1. 7H + 1.4F)l6 l S=D+H+F rp Where:
S = Required section capacity U = Required ultimate strength capacity D = Dead load, including hydrostatic load of internal controlled liquid 7 L =Live load H = Soil Load 8 W =Wind load E =Design earthquake F = Flood hydrostatic load to elevation 1007 feet
<t> = Strength reduction factor 1
<l The USD load factors for normal operating/service load conditions are consistent with Equation 9-1 and those in Section 9.3.4 of AC1318-71 (Reference 6.10). Note that these factors are less severe than those required by the ACI 318-63 Code for the USD load combination of Section 1506 equation ( 15-1 ). However, 1.40 and 1. 7L load factors were implemented in the ACI318-71 Code (References 6.10 and 6.13) and have remained constant up to today. In addition, soil pressure (H) (lateral earth pressure or ground water pressure for design of structures below grade) is added to align with editions of ACI 318 issued subsequent to 1963.
2l The USD load combination for normal operating/service conditions is the same as Equation 9-2 of ACI318-71, except H. Even though Equation 15-2 of ACI318-63 specifies that U = 1.250+1.25L+1.25W, which is less severe than Equation 9-2 of ACI318-71 when W governs design, the latter equation is used to avoid selectively using load factors from different codes (ACI 318-63 and ACI 318-71 ).
LIC-17-0059 Page 2 3
<l When D or L reduces the effect of W, the corresponding coefficients shall be taken as 0.90 for D and zero for L. This note, which accounts for Equation 9-3 of ACI318-71, will be added to the updated USAR.
4
<l The USD load combination for normal operating/service conditions meets the ACI 318-71 Section 9.3.3 requirement that U shall be at least equal to 1.05D+1.275L+1.4E. Even though Section 1506 (a) 3 of ACI 318-63 specifies that U = 1.25D+1.25L+1.25E, which is less severe than 1.05D+1.275L+1.4E from Section 9.3.3 of ACI318-71 when E governs design, the latter equation is used to avoid selectively using load factors from different codes (ACI 318-63 and ACI 318-71).
(s) When D or L reduces the effect of E, the corresponding coefficients shall be taken as 0.90 for D and zero for L. This note, which accounts for Equation 9-3 as modified per Section 9.3.3 of ACI318-71, will be added to the updated USAR.
6
< l The USD load combination for normal operating/service load conditions is revised to consider dead load (D) in combination with hydrostatic flood load (F) and lateral soil pressure (H). This change is consistent with ACI 318-71 Section 9.3.5 requiring that U shall be at least equal to 1.4D+1.7L+1.4F. Where lateral soil pressure H must be included in design, His substituted for L. ACI 318-63 is silent regarding proper combination of hydrostatic flood load and lateral soil pressure.
7
< l Hydrodynamic pressure of internal controlled liquid shall be accounted for in Load Combination 3.
<Bl Dynamic effects of lateral soil pressure H shall be accounted for in Load Combination 3.
These changes will be applied to new designs or to re-evaluations of existing reinforced concrete structures of the Auxiliary Building (not including the foundation mat or the Spent Fuel Pool).
For extreme conditions, the no loss-of-function USD load combinations in USAR 5.11.3.5 will remain unchanged. However, a clarification to load combinations involving soil load (H), which was included in design basis calculations, is added to the USAR. This is not considered a change as it is intended to clarify the license basis.
LIC-17-0059 Page 1 ENCLOSURE 3 Fort Calhoun Station Unit No.1 Renews Facility Operating License No. DPR-40 Revised Updated Safety Analysis Report (Mark-Up)
Sections 5.11.3.1 a. and 5.11.3.4
USAR-5.11 Information Use Page 5 of 20 Structures Other Than Containment Rev. XX 5.11.3.1 Loading
- a. Dead Load (D)
Dead loads included the weight of the structure and other items permanently affixed to it such as equipment, non-structural toppings, partitions, cables, pipes and ducts.
Dead loads also include interior hydrostatic fluid loads which are known and controllable. This type of loading is often sustained over time . This classification is consistent with /\CI 34Q Q7 *.vhich defines fluid loads as "loads due to weight and pressures of fluids with well defined densities and controllable maximum heights."
USAR-5.11 Information Use Page 5 of 20 Structures Other Than Containment Rev. XX 5.11.3.4 Operating Basis Load Combinations for Class I Concrete Structures Class I structures were designed on the basis of working stress for the following load combinations:
S= O+H+L S = 0 + L + H + W or E S= O+H+F where:
S= Required section capacity D- Dead load L Live load, including hydrostatic load W- Wind load E Design earthquake F- Hydrostatic load to elevation 1007 feet The ACI Code 318-63 design methods and allowable stresses were used for reinforced concrete.
'A'ith the approval of Amendment No. XX. Tthe Auxiliary Building. with the exception of the foundation mat and the Spent Fuel Pool. design criteria changed to implement the ultimate strength design method for normal/operating service conditions for changes and reanalysis using the following load combinations from sections 9.3.1 through 9.3.5 of ACI 318-71 (reference xx):
U = 1 (1.40 + 1.7L + 1.7H)
¢ U = 1 (1.050 + 1.275L + 1.275W + 1.275H) <1)
¢ U = 1 (1.050 + 1.275L + 1.40E + 1.275Hl <2 )
¢ U = 1 (1.40 + 1.7H + 1.4F)
¢
USAR-5.11 Information Use Page 5 of 20 Structures Other Than Containment Rev. XX where:
U = Ultimate strength capacity per the ACI 318-63 Code
<f.>= Reduction factors in accordance with the following values and applications:
<f.>= 0.90 for concrete in flexure
<f.>= 0.90 for mild reinforcing steel in direct tension excluding mechanical or lapped splices
<f.>= 0.85 for mild reinforcing steel in direct tension with lapped or mechanical splices
<f.>= 0.85 for diagonal tension. bond and anchorage
<f.>= 0.70 for tied compression members
( 1) When D or L reduces the effect ofW. the corresponding coefficients shall be taken as 0.90 forD and zero for L.
(2 ) When D or L reduces the effect of E. the corresponding coefficients shall be taken as 0.90 forD and zero for L.
The ultimate strength capacity of Class I reinforced concrete structures is determined in accordance with the ultimate strength provisions from the ACI 318-63 Code using the capacity reduction factors. <f.> listed above.
LIC-17-0059 Page 1 ENCLOSURE 4 Fort Calhoun Station Unit No.1 Renews Facility Operating License No. DPR-40 Revised Updated Safety Analysis Report (Clean)
Sections 5.11.3.1 a and 5.11.3.4
USAR-5.11 Information Use Page 11 of 16 Structures Other Than Containment Rev. XX 5.11.3.1 Loading
- a. Dead Load (D)
Dead loads included the weight of the structure and other items permanently affixed to it such as equipment, non-structural toppings, partitions, cables, pipes and ducts.
Dead loads also include interior hydrostatic fluid loads which are known and controllable. This type of loading is often sustained over time.
USAR-5.11 Information Use Page 12 of 16 Structures Other Than Containment Rev. XX 5.11.3.4 Operating Basis Load Combinations for Class I Concrete Structures Class I structures were designed on the basis of working stress for the following load combinations:
S= D+H+L S= 0 + L + H + W or E S= O+H+F where:
S= Required section capacity The ACI Code 318-63 design methods and allowable stresses were used for reinforced concrete.
The Auxiliary Building, with the exception of the foundation mat and the Spent Fuel Pool, design criteria changed to implement the ultimate strength design method for normal/operating service conditions for changes and reanalysis using the following load combinations from sections 9.3.1 through 9.3.5 of ACI 318-71 (reference xx):
U = 1 (1.40 + 1.7L + 1.7H)
¢>
U = 1 (1.050 + 1.275L + 1.275W + 1.275H) (1)
¢>
U = 1 (1.050 + 1.275L + 1.40E + 1.275H) (2 )
¢>
U = 1 (1.40 + 1.7H + 1.4F)
¢>
USAR-5.11 Information Use Page 13 of 16 Structures Other Than Containment Rev. XX where:
U = Ultimate strength capacity per the ACI 318-63 Code
¢ = Reduction factors in accordance with the following values and applications:
¢ = 0.90 for concrete in flexure
¢ = 0.90 for mild reinforcing steel in direct tension excluding mechanical or lapped splices
¢ = 0.85 for mild reinforcing steel in direct tension with lapped or mechanical splices
¢ = 0.85 for diagonal tension, bond and anchorage
¢ = 0. 70 for tied compression members 1
( ) When D or L reduces the effect of W, the corresponding coefficients shall be taken as 0.90 forD and zero for L.
(2 ) When D or L reduces the effect of E, the corresponding coefficients shall be taken as 0.90 forD and zero for L.
The ultimate strength capacity of Class I reinforced concrete structures is determined in accordance with the ultimate strength provisions from the ACI 318-63 Code using the capacity reduction factors , ¢ listed above.