U.S. EPR Critical Sections Selection Methodology Meeting

NRC Meeting - U.S. EPR Critical Sections Selection Methodology – Sep 18, 2009 1

Joe Harrold, P.E.

Engineering Supervisor

New Plants Deployment

AREVA NP Inc. and the NRCSeptember 18, 2009

ObjectivesTo present the AREVA Critical Section Selection Methodology, focusing on changes and additions made to the methodology to address NRC observations provided during the 19-Jun-09 meeting,

To receive NRC feedback on the proposed FSAR changes provided on 20-Aug-09, and

NRC Meeting - U.S. EPR Critical Sections Selection Methodology – Sep 18, 2009 2

To obtain NRC concurrence on the adequacy of the AREVA Critical Section Selection Methodology.

TopicsDefinition of Critical Sections

Three-Tiered Critical Sections Selection Criteria

Qualitatively Defined Critical Sections

Quantitatively Defined Critical Sections

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Supplementary Critical Sections

Overview of Critical Sections

Summary and Conclusion

Definition of U.S EPR Critical Sections

“Critical sections are those portions of individual Seismic Category I structures (i.e., shear walls, floor slabs and roofs, structure-to-structure connections) that are credited in prevention or mitigation of consequences of postulated design basis accidents

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consequences of postulated design basis accidents, or expected to experience the largest structural demands during design basis conditions, or needed for evaluation of an essentially complete design.”

Definition of U.S EPR Critical Sections

“Critical sections are those portions of individual Seismic Category I structures (i.e., shear walls, floor slabs and roofs, structure-to-structure connections) that are credited in prevention or mitigation of consequences of postulated design basis accidents

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consequences of postulated design basis accidents, or expected to experience the largest structural demands during design basis conditions, or needed for evaluation of an essentially complete design.”

Definition of U.S EPR Critical Sections

“Critical sections are those portions of individual Seismic Category I structures (i.e., shear walls, floor slabs and roofs, structure-to-structure connections) that are credited in prevention or mitigation of consequences of postulated design basis accidents

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consequences of postulated design basis accidents, or expected to experience the largest structural demands during design basis conditions, or needed for evaluation of an essentially complete design.”

Definition of U.S EPR Critical Sections

“Critical sections are those portions of individual Seismic Category I structures (i.e., shear walls, floor slabs and roofs, structure-to-structure connections) that are credited in prevention or mitigation of consequences of postulated design basis accidents

NRC Meeting - U.S. EPR Critical Sections Selection Methodology – Sep 18, 2009 7

consequences of postulated design basis accidents, or expected to experience the largest structural demands during design basis conditions, or needed for evaluation of an essentially complete design.”

“Once detailed design of Critical Sections is complete, the design for that structure is essentially complete for safety evaluation purposes. Thus, Critical Sections taken as a whole are analytically representative of an “essentially complete” U.S. EPR

Essentially Complete U.S EPR Design

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representative of an essentially complete U.S. EPR design and their structural design adequacy provides reasonable assurance of overall U.S. EPR structural design adequacy.”

Three-Tiered U.S. EPR Critical Section Selection Methodology

The Critical Section Selection Methodology embodies three complimentary approaches:

Qualitative Approach

Quantitative Approach

Supplementary Approach

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Definition of the Qualitative Approach

“The qualitative approach is applied to portions of the U.S. EPR NI Common Basemat Structures that are credited in the risk mitigation of the nuclear power plant under design basis loading conditions to provide protection of public safety

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conditions, to provide protection of public safety through the physical plant boundaries.”

Critical Sections Selected by the Qualitative Approach (8 total)

Reactor Containment Building

(1) Liner Plate

(2) Typical Cylinder Wall & Buttress

(3) Typical Dome & Dome Ring Areas

(4) Connection of Containment Wall to NI Basemat

(5) Equipment Hatch Area

R t B ildi I t l St t

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Reactor Building Internal Structures

(6) Primary Shield Wall/Reactor Vessel Support Area

NI Basemat & Reactor Building Internal Structures Base Slab

(7) Entire basemat

Fuel Building Internal Structures

(18) Spent Fuel Pool Walls and Floor Slab

These are identified by both qualitative and quantitative approaches.

Definition of the Quantitative Approach

“The quantitative approach achieves identification of critical sections by a thorough analysis of force and moment results extracted from portions of the global static model not already

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defined as critical sections by the qualitative approach.”

Critical Sections Selected by the Quantitative Approach (13 total)

Reactor Building Internal Structures

(8) Operating Floor Area

(9) Elevation +1.50m Heavy Slab & Support Walls

(10) SG Cubicle Area Walls

Safeguard Building 2/3 Hardened Shell

(11) Walls from Top of NI Basemat to Grade

Safeguard Building 2/3 Internal Structures

(12) Exterior Walls from Top of NI Basemat to Grade

(13) Floor Slab at Elevation 0.00m

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( 3) oo S ab at e at o 0 00

Safeguard Buildings 1 & 4

(14) Main Steam & Feedwater Valve Room Walls & Slabs

(15) Exterior Walls from Top of NI Basemat to Grade

Fuel Building Hardened Shell

(16) Walls from Top of NI Basemat to Grade

Fuel Building Internal Structures

(17) Major Walls from Top of NI Basemat to Elevation +1.00m

(18) Spent Fuel Pool Walls & Floor Slab

Building-to-Building Connections

(19) RSB Typical Wall Areas & Connection Between RSB Wall and SB/FB Roof Slabs

Reactor Shield Building:

(20) Typical Dome to Wall Transition Areas

U.S. EPR Critical Sections Selection Methodology-Supplementary Approach

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Se-Kwon Jung, Ph.D., P.E.

Civil/Structural Engineer

New Plants Deployment

Selection of Supplementary Critical Sections for the U.S. EPR

Critical Sections by the Qualitative and Quantitative Approaches

Most parts of the RCB and NI Basemat are covered by the qualitatively defined critical sections.

Limited portions of the RBIS, SBs, and FB are identified as quantitatively defined critical sections.

No critical sections are identified for non-NI Seismic Category I structures.

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Supplementary Critical Sections

Sections that constitute significant portions of the Seismic Category I structures in terms of their physical dimensions (i.e., wall and slab surface areas).

Sections that serve as major lateral and gravity load resisting structural elements for non-NI Seismic Category I structures (i.e., Emergency Power Generating Building (EPGB) and Essential Service Water Building (ESWB)).

Surface Area Comparisons for Critical Sections and U.S. EPR Structures

»Ratio of Sum of Surface Areas of NI Critical Sections to Total Surface Area of NI Structures,

NI Area Ratio 1 = 29 %

»Ratio of Sum of

RBIS Slab 8 & 9 0.33 0.75

RBIS Wall 9 & 10 0.12 0.63

SB23 Slab 13 0.13 0.15

SB23 Wall 12 0.07 0.26

NI Building Name

Slab/Wall

CriticalSections

Surface Area Ratio 1*

Surface Area Ratio 2**

RSB Slab/Wall 19 & 20 0.48 1.00

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»Ratio of Sum of Surface Areas of All Sections Typified by Critical Sections to Total Surface Area of NI Structures,

NI Area Ratio 2 = 57 %

SB23S & FBS

Slab 19 0.30 0.58

FBS Wall 16 0.13 0.73

FB Wall 17 & 18 0.19 0.69

FB Slab 18 0.05 0.05

SB1 & SB4 Slab 14 0.06 0.07

SB1 & SB4 Wall 14 & 15 0.18 0.65

*: Ratio of Sum of Surface Areas of Critical Sections to Total Surface Area of NI Structure

**: Ratio of Sum of Surface Areas of All Sections Typified by Critical Sections to Total Surface Area of NI Structure

Additional candidate critical sections necessary to increase coverage areas

30 cm thick walls for SB23

50 cm thick slabs for SB23

40 and 50 cm thick slabs for FB

50 cm thick slabs for SB1 and SB4

Supplementary critical sections selected

Selection of Supplementary Critical Sections for the U.S. EPR

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Supplementary critical sections selectedSafeguard Building 2/3 Internal Structures

• (21) Floor Slab at Elevation -5.00mFuel Building Internal Structures

• (22) Floor Slab at Elevation -6.20mSafeguard Building 2/3 Internal Structures

• (23) Shear Wall Next to RSB

Ratio of sum of surface areas of all sections typified by NI critical sections to total surface area of NI structures

NI Area Ratio 2 = 77 %

Critical Sections 21: Safeguard Building 2/3 Internal Structures – Floor Slab at Elevation -5.00m

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Critical Section 22: Fuel Building Internal Structures – Floor Slab at Elevation -6.20m

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Critical Section 23: Safeguard Building 2/3 Internal Structures – Shear Wall Next to RSB

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Emergency Power

Generating Building

Plan View Elevation ViewBuilding

A A’

<A A’>

(EPGB)

Critical Sections for EPGB and ESWB – Plan and Elevation Views

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B

B’

<A-A >

<B-B’>4 ESWB Critical Sections (Critical Sections 29 Thru 32)

Essential Service Water

Building

5 EPGB Critical Sections (Critical Sections 24 Thru 28)

(ESWB)

ABCDEFGHJ

CS 24

CS 26: Reinforced Concrete Slab and Composite Beams at Elevation 51’ – 6”

CS 26

CS 27: Shear Wall on Column Line C

CS 27

CS 28: Emergency Power Generating Building – Shear Wall on Column Line E

CS 28

CS 25

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CS 24: Emergency Power Generating Building –Basemat Foundation at Elevation – 0’-0”

EPGB - Elevation

A BC D E F G

H J

11

12

13

14 EPGB Pl Vi

CS 24CS 25: Emergency Power Generating Building –

Shear Wall on Column Line 11CS 25CS 26CS 27CS 28

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CS 27: Emergency Power Generating Building –Shear Wall on Column Line C

CS 28: Shear Wall on Column Line E

14

15

16

17

18

19

EPGB – Plan View

1 2 3 4 5 CS 29

CS 30: Shear Wall on

CS 30

CS 31: Fan Deck Slab at Elevation 63’ - 0”

CS 31CS 32

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ESWB – Elevation

CS 29: Essential Service Water Building –Basemat Foundation at Elevation – 16’-0”

CS 30: Shear Wall on Column Line 4

3

4

5

ESWB – Plan View

CS 29CS 30CS 31

CS 32: Essential Service Water Building – Shear Wall on Column Line D

CS 32

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CS 30: Essential Service Water Building – Shear Wall on Column Line 4

B ACDEF

1

2

Critical Sections for EPGB and ESWB and Surface Area Comparisons

EPGB & ESWB Critical Sections Identified by the Supplementary Approach (9 total)

Emergency Power Generating Building

• (24) Basemat Foundation at Elevation 0’-0”• (25) Shear Wall on Column Line 11• (26) Reinforced Concrete Slab and Composite Beams at Elevation 51’-6”• (27) Shear Wall on Column Line C• (28) Shear Wall on Column Line E

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• (28) Shear Wall on Column Line EEssential Service Water Building

• (29) Basemat Foundation at Elevation 16 ft - 0 in• (30) Shear Wall at Column Line 4• (31) Fan Deck Slab at Elevation 63 ft – 0 in• (32) Shear Wall on Column Line D

Ratio of sum of surface areas of EPGB & ESWB critical sections to total surface area of EPGB & ESWB, EPGB & ESWB Area Ratio 1 = 43 %

Ratio of sum of surface areas of all sections typified by EPGB & ESWB critical sections to total surface area of EPGB & ESWB, EPGB & ESWB Area Ratio 2 = 100 %

Critical Sections Identified by the Supplementary Approach (12 Total)

Safeguard Building 2/3 Internal Structures

(21) Floor Slab at Elevation -5.00m

Fuel Building Internal Structures

(22) Floor Slab at Elevation -6.20m

Safeguard Building 2/3 Internal Structures

(23) 0.30m Thick Shear Wall Next to RSB

Emergency Power Generating Building

»Ratio of Sum of Surface Areas of All Sections Typified by Critical Sections to Total Area of U.S. EPR Structures,U.S. EPR Area Ratio 2 = 84 %

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(24) Basemat Foundation at Elevation 0’-0”

(25) Shear Wall on Column Line 11

(26) Reinforced Concrete Slab and Composite Beams at Elevation 51’-6”

(27) Shear Wall on Column Line C

(28) Shear Wall on Column Line E

Essential Service Water Building

(29) Basemat Foundation at Elevation 16 ft - 0 in

(30) Shear Wall at Column Line 4

(31) Fan Deck Slab at Elevation 63 ft – 0 in

(32) Shear Wall on Column Line D

Overview of Critical Sections for NI Common Basemat Structures

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NI Critical Section Overview – 1/3

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NI Critical Section Overview – 2/3

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NI Critical Section Overview – 3/3

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Summary and Conclusion

Definition of critical sections

Three-tiered critical section selection criteria

32 U.S. EPR critical sections identified by qualitative, quantitative, and supplementary approaches

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Essentially complete design of U.S. EPR

Summary of NRC Observations and Resolutions on June 19 Meeting

A. The current methodology is only applied to the NI structures. The scope for selection of the critical sections should consider all Seismic Category I structures.

Critical sections for other Seismic Category I structures are added.

B. The methodology refers to the selection of critical sections “in lieu of a complete design." This does not appear to be consistent with the need to use critical sections to represent an "essentially complete design."

Editorial changes have been made to refer to an essentially complete design as suggested

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suggested.

C. The current methodology in several cases refers to selection of critical sections to address design basis accidents (DBAs) / loss of coolant accidents (LOCAs). AREVA indicated that this should be revised to consider all loads and load combinations that are part of the design basis of the plant.

Revisions have been made as suggested.

D. In addition to using "qualitative" criteria and "quantitative" criteria, AREVA agreed that a third criterion which ensures that an adequate "representation of structural elements" throughout each of the Seismic Category I structures should also be included in the methodology.

Supplementary approach has been added.

Summary of NRC Observations and Resolutions on June 19 Meeting

E. For the AREVA calculation identified above, the critical sections which require approval from the NRC should be identified as Tier 2* not Tier 2.

Correction has been made.

F. For the AREVA calculation identified above, the qualitative criteria should also be applied to the fuel building because one of the functions of this building is to prevent release of radioactive material.

The qualitative approach has been applied to the Fuel Building.

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G. For the AREVA calculation identified above (Section 2.1), the qualitative criteria dealing with the "defense in depth" needs to be revised. The "safety margin" should not be considered to be part of the defense in depth, but rather is in addition to defense in depth.

Editorial changes have been made as suggested.

H. The third criterion consisting of adequate representation of structural elements (see Item D above) should include other types of structural elements and locations not captured by the qualitative and quantitative criteria, such as structural steel members and major discontinuities (e.g., large openings in structural walls/slabs).

Supplementary approach has been added.

Thank you!

Any Questions?

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Any Questions?