ML18191A235

Response to Request for Additional Information Protection Against Pipe Breaks Outside Containment

ML18191A235
Person / Time
Site:	Columbia
Issue date:	03/26/1975
From:	Stein J Washington Public Power Supply System
To:	Giambusso A Office of Nuclear Reactor Regulation
References
G02-75-90
Download: ML18191A235 (12)

Text

Washington Public Power Supply System A JOINT OPERATING AGENCY P, O. BOX 968 3000 GEO. WAIHINOTON WAY R>CHl.ANO. WASHINOTON 09352 PHONC (509) 946-968l Docket No. 50-397 March 26, 1975 G02-75-90 Mr. A. Giambusso, Director Division of Reactor Licensing Office of Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission Washington,- DC 20555 p0CKETED

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Subject:

WPPSS NUCLEAR PROJECT NO. 2 RESPONSE'TO REQUEST FOR ADDITIONAL INFORMATION o P,PR "3.1975 PROTECTION AGAINST PIPE BREAKS OUTSIDE CONTAINMENT u.s. Nua~

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Reference:

Letter from W. R. Butler to J. J. Stein, Transmitting Request for Additional Information Dated January 17, 1975 (GI2-75-10)

Dear Mr. Giambusso:

The attachment provides information requested-in the referenced letter.'his information has been provided in a question and response format; Forty (40) copies of the attachment are being submitted for your review.

Very truly yours, J .. TEIN Managing Director JJS:GLG:ski Attachment cc: JJ Byrnes - Burns and Roe, Inc.

'BW Kennedy - Bonneville Power Administration 3470 FA MacLean - General Electric Company JJ Verderber - Burns and Roe, Inc.

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Letter, JJ Stein to A Gi sso, entitled "Protection Aga Pipe Breaks Outside Containment," dated March 26, 1975, Letter No. G02- 5-90.

STATE OF WASHINGTON )

) ss COUNTY OF BENTON )

J. J. STEIN, Being'first duly sworn, deposes and says: That he is the Managing Director of'the WASHINGTON PUBLIC POWER SUPPLY SYSTEM, the applicant herein; that he is authorized to submit the foregoing on behalf of said applicant; that he has read the foregoing and knows the contents thereof; and believes the same to be true to the best of his knowledge.

DATED 'll' 1975 J.J T N On this day personal ly appeared before me J. J. Stein to me known to be the individual who executed the foregoing instrument and acknowledged that he signed the same as his free act and deed for the uses and purposes ther ein mentioned.

GIVEN under my hand and seal this ZVl day of l975.

WMWc: ~

Not y Pu lic in and for State of Washington Wza ..2c ~

Residing at

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%%PPSS NP No. 2 PROTECTION AGAINST PIPE BREAKS OUTSIDE CONTAINMENT RESPONSES TO MECHANICAL ENGINEERING BRANCH QUESTIONS QUESTION 1:

In the discussion of AEC Item 2, you quote "alternate rules for determination of postulated pipe break locations" from 2.1.2 of WPPSS-74-2-Rl. State specifically whether these "alternative rules" are intended to apply only to ASME Code Class 2 and 3 piping.

RESPONSE

The alternate rules for determination of postulated pipe break locations quoted in the discussion of AEC Item 2 are not restricted to ASME Code Class 2 and 3 piping, but apply equally to ASME Code Class 1 piping.

QUESTION 2:

In the discussion of AEC Item 3, you quote from the -Rl report paragraph 2.2.1 a procedure for using the ratio of hoop and axial stresses to determine whether a longitudinal split or a circumferential"no break will be considered between and you quote your criterion of significant. difference the hoop and axial stresses" for consideration of both types of break. You should provide a more quantitative criterion.

The staff considers a stress ratio of 1.5 to be necessary to justify the consideration of onlya agivenlongitudinal split or of only a circumferential break at location.

RESPONSE

The report WPPSS-74-2-Rl quoted in the discussion of 1975.

AEC Item 3 has been reissued as Revision 1 dated March, In this revision, the referenced paragraph 2.2.1 has ofbeen to include the more quantitative criterion consid-eration of only longitudinal split, or only circumferential

'odified break at any particular locations as follows:

2.2.1 At each of the postulated break locations, consider-ation will be given to the occurrence of either a longitudinal

PSS NP No. 2 split or circumferential break. Both types of breaks orwill be if considered, if the rules of 2.1.2 above are applied, the maximum stress ranges in the circumferential and axial directions are not significantly different. Only one type break will be considered as follows:

a. If the result of a detailed stress analysis, such as finite element analysis, indicates that the maximum stress range in the axial direction is at least 1.5 times that in the

'ircumferential direction, only a circum-ferential break will be postulated.

b. If this type of analysis indicates that the maximum stress range in the circumferential direction is at least 1.5 times that in the axial direction, only a longitudinal split will be postulated.

QUESTION 3:

In the discussion of AEC Item 3, you quote from paragraph 2.2.4 of the -Rl report in regard to the movement of the free end of a pipe't a postulated circumferential break. The staff feels that. an acceptable criterion would "require that except for movement (such as one diameter lateral displace-ment) assumed in order to establish a design basis jet re-action, pipe whipping should be assumed to occur in a direc-tion which logically results from the effect of the jet re-action upon the piping configuration, including the geometry, strength, and stiffness of the piping and its supports, re-straints, and snubbers.

RESPONSE

The report WPPSS-74-2-Rl quoted in the discussion of AEC Item 3 has been reissued as Revision 1 dated March, 1975.

In this revision, the referenced paragraph 2.2.4 has been modified as follows:

2.2.4 For circumferential breaks, the free end of the moving pipe will be assumed to move within a plane determined by the free end segment and the pipe segment formed by the first change in direction (such as an elbow) . The restraint re-action force will be assumed to be parallel to the axis of

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~WPPSS NP No. 2 the free end segment and in a direction compatible with the jet reaction. The pipe segment formed by the first change in if direction will be constrained by appropriate restraints, necessary. This type of break event will not cause dynamic instability (large amplitude oscillations) since analyses have shown that critical length required for this phenomenon is substantially greater than any major pipes in the drywell.

WPPSS NP No. 2 PROTECTION AGAINST PIPE BREAKS OUTSIDE CONTAINMENT RESPONSES TO'TRUCTURAL ENGINEERING BRANCH QUESTIONS QUESTION 1:

Provide a statement that the design criteria and the design methods for the Category I structures are in accordance with Document (B) cited above.

RESPONSE

The design criteria and the design methods for Category I structures are in'accordance with Document (B), Structural En ineerin Branch, Directorate of Licensin , entitled "Structural Design Criteria for Evaluating the Effects of High-Energy Pipe Breaks in Category I Structures Outside the Containment" dated June 1973.

The analytical procedure used to estimate the structural re-sponse of barr'iers to pipe break effects, and for predicting their adequacy is described in Section 7.2 of Appendix C, "Structural Response to Pipe Break Effects", in Report WPPSS-74-2-R3., The level of conservatism in this procedure is comparable to that provided by the analysis procedure described in'he paper by Williamson and Alvy entitled "Impact Effects of Fragments Striking Structural Elements",

NP-6515 (1957) referred to in Section E.2 of Document (B) .

The Williamson and Alvy paper formulates the solution to the problem of physical missiles with ballistic characteristics (projectile-like metal fragments) impacting structural isele-ments whereas the formulation presented in Appendix C more suitable to reflect in a conservative manner the response of structural elements to pipe break effects.

PSS NP No. 2 QUESTION 2:

Include a discussion of ductility factors and their use for members under combined loading.

RESPONSE

The ensuing discussion relates to Appendix C of the report

,WPPSS-74-2-R3.

In determining the required resistance force of a structural element subjected to postulated pipe break effects, elasto-plastic behavior of the element is assumed, and the maximum allowable ductility ratios are selected from the revised Table C-2, attached. The tabulated values are limited, generally, to less than 50% of the ductility ratio values corresponding to structural collapse defined in Reference 6 to Appendix C.

Since the elasto-plastic behavior assumption negates the use of the principle of superposition of effects, when using the Energy Balance Method (refer to paragraph 7.2 of Appendix C),

all applicable concurrently applied loads/effects will be considered simultaneously.

After determining the structural response of an element sub-jected to postulated pipe break effects, assuming elasto-plastic behavior, a verification will be made to ensure that maximum calculated deflections will not result in loss of function of the element and will not impair the proper func-tioning of other safety related systems.

t e J PSS NP No. 2 TABLE 2 (Revised)

MAXIMUM ALLOWABLE DUCTILITY RATIOS Reinforced Concrete Structural Com onents Tension reinforced concrete beams and slabs, (flexure controls design); 0. 10 10 p

• Doubly reinforced concrete beams and slabs, (flexure controls design); 0.10

~pp Reinforced concrete columns, walls and other elements exhibiting brittle fracture, (compression controls design); 1.3 Steel Structural Com onents Steel beams under lateral loads, (flexure, compression and shear);

(Note: members proportioned to preclude lateral and local buckling) 13 Steel Columns (Note: members proportioned to preclude elastic buckling) 1.3 Members stressed in tension only 0.5 u Y

Composite T beams

• p is the ratio of tensile reinforcement and must satisfy the limitations:

As 0.0025 w p = bd ( 0.015;

• • p's the ratio of compression reinforcement and must satisfy the limitations:

A' p' bd - 0.0025; e

u is the ultimate strain of the material; e is the yield strain of the material.

0 v

p