ML17194B092

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Forwards Draft Evaluation of SEP Topic III-7.B, Design Codes,Design Criteria & Loading Combinations. Response Requested within 30 Days
ML17194B092
Person / Time
Site: Dresden Constellation icon.png
Issue date: 05/20/1982
From: Oconnor P
Office of Nuclear Reactor Regulation
To: Delgeorge L
COMMONWEALTH EDISON CO.
Shared Package
ML17194B093 List:
References
TASK-03-07.B, TASK-3-7.B, TASK-RR LSO5-82-05-037, LSO5-82-5-37, NUDOCS 8206010480
Download: ML17194B092 (8)
v • d • e


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May 20, 1982 l

Oocket'No. 50-237 LS85-82 05-037

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I Mr'. L. Del George Director of Nuclear Licensing Commonwealth Edison Company Post Office Box 767 Chicago, Illfno1s 60690

Dear Mr. DelGeorge:

SUBJr8r *

~. SEP TOPIC III-7.B, DESIGN CODES, DESIGN CRITERIA ANO LOAP COMBINATIONS - ORES![EN 2 Enclosed is a copy of our draft evaluation of SEP Topic III-7.B.

The eval uatfon identifies ;&B!eas of codes where changes have occurred to decrease safety margfn-S:

\\I~t also identfffes loads applicable to some or al 1 of the structures at Dresden 2 which have increased f n magnf tude.

You are to review how these areas of the codes were applied fn the desf gn of Dresden 2 and assess th@'rrent safety margins.

We are*

currently assessing the ~bf11ty of the drywell to withstand combined seismf c and LOCA loadings. These res.ults will be supplied to you as a supplement to this topic evaluation.

You are requested to examine the.facts upon which the staff has based its evaluation and respond by conffrmfngtthat the facts are correct or by identifying errors a.nd. supplying the corrected fnformatfon.

l4e encourage you to supply any other material that mf ght affect.the staffs evaluation of this topic or be significant in the integrated assessment of your facility.

YourC;response is requested wfthfn 30 days of recef pt of this letter.

Sf ncerely, 51,0~

>*{l 8206 0104<6°

Enclosure:

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As stated

.Paul O'Connor, Project Manager

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Op~ratfng Reactors Branch No. 5

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  • Division of L f cen~fng j

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cc w/enclosure:

See next page NRC FORM 318 (10-80) NRCM 0240 USGPO: 1981-335-960

Mr. L. DelGeorge cc Robert G. Fifzgibbons, Jr.

Isham, Li nco n & Beale

  • Counselors at Law Three First National Plaza - Suite 5200 Chicago, Illincis 60602 Mr. Douq Scott
  • Plant Superintendent Dresden Nuclear Power Station Rural Route #1 Morris, Illinois 60450
  • The.Honorable Tom Corcoran United States House of Represent~tives Washington, D. C.

20515

  • u *. S. Nuclear Regulatory Commission Resident Inspectors Office Dresden Station RR #1 Morris, Illinois 60450 Mary Jo Murray Assistant Attorney General Environmental Control Division 188 W. Randolph Street Su~ te 2315 Chicago, Illinois 606Gl Chainnan Board of Supervisors of cGrundy County Grunay-tourity Courthouse Morris, Illinois 60450 John F. Wolf, Esquire 3409 Shepherd Street Chevy Chase, Maryland 20015 Dr. Linda W. Little 500 Hennitage Drive Raleigh, North Carolina 27612.

Judge Forrest J. Remick

. The Carriage Ho~se - Apartment 205

. 2201 L Street, N. w.

Washington, D. c.

20037

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Illinois* Department of Nuclear Safety 1035 Outer Park Drive, 5th Floor Springfield, Illinois 62704 U. S. Environmental Protection Agency Federal Activities Branch.

Region V Office ATTN:

Regional Radiation Representative 230 South Dearborn Street Chicago, Illinois 60604 James G. Keppler, Regional Administrator Nuclear Regulatory Commission, Region III 799 Roosevelt Street Glen Ellyn, Illinois 60137

/).

SYSTEMATIC EVALUATION PROGRAM TOPIC II I -7. B DRESDEN 2 TOPIC:

III-7.B, DESIGN CODES, DESIGN CR!TERIA AND LOADING COMBINATIONS I.

INTRODUCTION SEP plants were generally designed and constructed during the time span from the late 1950's t~ late 1960's.

They were designea according ~o criteria and codes which di ff er from those accepted by the NRC for ne*,.,

plants.

The purpose of this topic is to assess the safety margins existing in Category I structures as a result of changes in design codes and criteria.

II *. REVIEW GUIDELINES The current licensing criteria which governs the safety issue in this topic is 10 CF~ 50, Appendix A, GDC 1, 2, and 4 as interpreted by Standard Review Plan 3.S.

III.

RELATED SAFETY TOPICS The following SEP topics are related to III-7.B:

1.

I II-2, Wind and Tornado Loadings

2.

III-3.A, Effects of High Water and Level on Structures

3. III-4.A, Tornado ~issiles
4.

III-5.A, Effects of High Energy Pipe Breaks Inside Containment S.

III-5.8, Effects of High Energy Pipe Breaks Outside Containment

6.

III-6, Seismic Design Considerations

7. V I-2.D, Mass and Energy Release for Postulated Pipe Break Inside Containment
8.

VI-3, Containment Pressure and Heat Removal Capability IV.

EVALUATION The evaluation is based on a Technical Evaluation Report (TER) prepared by the Franklin Research Center (FRC) in conjunction with the NRC staff through contract.

The report is entitled, ~Design Codes, Design Criteria and Loading Combinations" and is attached to this Safety Evaluation Report as Enclosure (1 ).

I~

  • We have compared structural design codes employed in the design of Category I structures at Dresden 2 to present codes.

This was done through generic code versus code comparison without investigating specifically how the original code was applied to the Dresden 2 design; however, after reviewing drawings of structures at Dresden 2, we concluded that certain portions of the codes were not applicable to Dresden 2 because the types of structures to which the codes are referring were non-existent at Dresden 2.

We have compared the loads and loading combinations employed in the design of Dresden 2 as described in the Dresden 2 FSAR to those required today.

A result of these comparisons is that a number of code changes could potentially impact significantly margins of safety (denoted by scale A and Ax in Enclosure l ).

This can be attributed to several factors such as:

l) New codes have imposed stricter limitations than old,

2)

New codes have included sections governing design of certain types of structures which were not included in the older codes,

3) Design loads required today were not included in the plant design, and
4) Certain load combinations judged to be significant were not included in plant design.

The code changes of concern from Enclosure (l) are:

(See next page)

Structural Elements to be Examined Code Change Affecting These Elements Composite Beams

l. Shear connectors in composite beams
2.

Composite beams or girders with formed steel deck Compression Elements With width-to-thickness ratio higher than speci-fied in 1.9.l.2 Tension Members When load is transmitted by bolts or rivets C6Mections

l. Beam ends with top flange coped, if subject to shear 2~

Connections carrying moment or restrained member connection Members Designed to Operate in an Inelastic Regime Spacing of lateral bracing Short Brackets and Corbels having a shear span-to-depth ratio of unity or less New Code Old Code AISC 1980 l.ll. 4 l.ll.5 AISC 1980.

l. 9.1.2 and Appendix C AISC 1980
  • Double dash (--) indicates that no provisions were provided in the older code.

.Y Structural Elements to be Examined Shear Walls used as a primary load~arrying member Precast concrete Structural Elements, where shear is not a member of diagonal tension Concrete Regions Subject to High Temperatures Time-dependent and position-dependent temperature variations Columns with Spliced Reinforcement subject to stress reversals:

fy in compression ro 1/2 fy in tension Steel Embedments used to transmit load to concrete All elements whose failure under impulsive and impactive loads must be precluded containment Vessels

l.
2.
3.
4.

containment vessels of materials no longer listed as code acceptable COntainment V*essels containing telltale holes COr 1inment vessels de~-~ned by formula and subject to substantial loads Stiffening rings for cylindrical shells subject to external pressure Code Change Affecting These Elements New Code Old Code ACI 349-76 ll.16 ACI 349-76 11.15 ACI 349-16 Appendix A ACI 349-76 7.10.3 ACI 349-76 Appendix B ACI 349-76 Appendix C ASME Sec. III, NE-3112.4 ASME Sec. III, ASME Sec. III, NE-3131 ASME Sec. III, NE.,..3133. 5 (a)

ACI 318-63 ACI 318-63 ACI 318-63 ACI 318-63 805 ACI 318-71 ASME Sec. VIII, UG-23 ASME Sec. VI II, 1962 UG-25(d)

ASME Sec. VIII, ASME Sec. VIII, UG-29 Structural Elements to be Examined Code Change Affecting These Elements

s. Different materials used for the shell.and stiffening rings
6. Vessels with reducer section with *reversed*

curvature when RI.It < 23

7. Vessels with pC>sitive locking devices - Quick actuating closures
e.

Pressure indicating devices for vessels having quick ectuating closures Shell Qpenings and Attachments

l. Openings and reinforcements.
2.
3.
4.

Provisions for fatigue analysis Reinforcement for openings Bellows expansion joints, over 6 inches in diameter Bellows - New design requirements Roofs New Code Old Code ASHE Sec. III, ASHE Sec. VIII, NE-3l33.5(b)

ASHE Sec. III, Fig. 3324.ll (a) (6)-l ASME Sec. III, NE-3327.l ASHE Sec. III, NE-3327.4 ASME Sec. III, NE-3331 (b)

ASHE Sec. III, NE-3334.l NE-3334.2 ASHE Sec. III, NE-3365(f)

ASHE Sec. III, NE-3365.2 ASME Sec. VIII/

Fig. UG-36 (d)

ASHE Sec. VIII, ASME Sec. VIII, ASME Sec. VIII, UG-36 AsHE Sec

  • VI II, tJG-40 (b)

UG-40(c)

ASHE Sec. VIII, ASHE Sec. VIII, Extreme environmental snow loads are provided by SEP Topic II-2.A.

NRC*

Reg. Guide 1.102 (Position 3) provides guidance to preclude adverse con*sequences from ponding or parapet roofs.

Failure of roofs not designed for such circumstances could generate impulsive loadings and water damage, possibly extending to Seismic Category I components of all floor levels.

4~.*

      • Section 10 of Enclosure (1) addresses load and load combination changes which occurred as a result of code changes and identifies specific plant structures for which various load combinations may be significant. Based upon a lack of detailed information on the stress results for loads and load combinations used during design of structures at Dresden 2, these loads and load combinations may be potentially significant.

We will issue a supplement to this SER which will assess the ability of the drywell to resist combined seismic LOCA loads that were developed in other SEP topics.

V.

CONCLUSIONS We conclude that after comparing design codes, criteria, loads and load combinations, a number of changes have occurred which could potentially impact margins of safety. These changes are identified above.

These differences between plant design and current licensing criteria should be resolved as follows:

lJ R.evi ew* Seismic Category I Structures at Dresden 2 to determine if any of the structural elements for which a concern exists are a part of the facility design of Dresden 2.

For those that are, assess the impact of the code changes on margins of safety on a plant specific basis, and

2) Examine on a sampling basis the margins of safety of Seismic Category I Structures for loads and load combinations not covered by another SEP topic and denoted by Ax in Enclosure (1 ).

(The load tables should be reviewed to assure their technical accuracy concerning applicability of the loads for each of the structures and their significance. The Category I structures considered should be reviewed to insure completeness.

Appendix A should be reviewed for accuracy of structural element applicability.)

Regarding the ability of the Dresden 2 drywell to resist seismic and LOCA loads a supplement to this evaluation is forthcoming.

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