ML19309A128
| ML19309A128 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 02/27/1973 |
| From: | Deyoung R US ATOMIC ENERGY COMMISSION (AEC) |
| To: | Allen R BECHTEL GROUP, INC. |
| References | |
| NUDOCS 8003260847 | |
| Download: ML19309A128 (7) | |
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'HIIS DOCUMENT CONTAINS POOR QUALITY PAGES i
Robert D. Allen, Vice Pre:ident Bechtel Corporation Fifty Donle Street San Francisco, California 94119
Dear Mr. Allen:
As a recult of our continuing review of Dcchtel Corporation Topicci Ecport LN-TCP-2 dated Septenbor 25, 1972, vc find that we need addi-j tional inforr.ction to ccuplete our cycluation. The specific infor=ation is listed in the enclosure.
The additional infornation chould be prcvided in cecordcace with the revic.i schedule we have cct:bliched for those applications referene-ing the topical.
We understand you are cvarc of thecc cchedules through your norcal connuaicction channels with the respective cpplicants and trill infor:c cach of the cpp11 cents that has referenced this topicci report in its application of your schedule for recponding to our nocdc.
Plence contcet us if you dcaire any diccuccion or clarification of th,e caterini required.
Sincercly, gging.s g a @ c,toYc d R. C. EcYoung, Accistant Director for Pressurized Vater P.ccctors Directorate of Licensing
Enclosure:
Ecquent for Additionci Infernation b
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3 REQUEST FOR ADDITIONAL INFORMATION BECHTEL TOPICAL BN-TOP-2 " DESIGN FOR PIPE BREAK EFFECTS" 0
1.
Judging from the governing equations (A-7 and A-9), and the subsequent derivations,pipewhipdynamiceffectswithregardtobothpipingand-restrainha is determined on the basis of an energy-balance approach for obtaining maximum deflections during the initial quarter cycle of response.
This method may not be representative if the break is associated with a 1
large energy reservoir in the system such as in the case of steam line i
breaks.
Experience to date indicates that the maximum response may i
occur af ter a few cycles due to the continuous energy input to the k
system.
In order to be considered acceptable'the subject report should l
be modified in accordance with the following:
i (a) Either replace the energy-balance approach by a time history response 1
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approach using a more rigorous dynamic analysis method to account for t
the mentioned rebound effects or, introduce the following coefficients i
to amplify the thrust prior to the use of er.ergy-balance approach.
(1) Use 1.5 if the thrust remains 70% or higher of its initial value after 0.2 second b,
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(2) Use 1.2 if the thrust redu'ces to less than 70% after 0.2 second.
(b) In lieu of the above provide a fully justified means of adjusting the proposed solutions using energy-balance approach to account for pipe rebound effects.
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Provide a more detailed description concerning the methods and 1
procedures used for computing the-piping stiffness K used in the p
i proposed analysis, especially the approaches used to account for the boundary effects.
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3.
Provide a more detailed explanation concerning the methods and 3
l procedures used to determine the loadings on the restraint if tne 1
f break is not postulated to occur directly at the restraint location.
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4.
Modify th.: criteria for determining (a) the piping systems in which breaks are postulated to occur, (b) the break locations, and (c) the I
' break orientations in various size piping to conform with the latest acceptable regulatory position as shown in Attachment I.
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i ATTACICIENT I s
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Acceptable Criteria of Pipe Whip Protections s'
I.
Protection against pipe whip is required for high energy fluid j
systems (or portions of systems) except where t
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Either of the following p'iping system conditions exist:
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t (a) the service temperature is 200 F or less (b) the desig\\
n pressure is 275 psig or less, or the pipin's,is physically separated (or isolated) from other B.
piping or components by protective barriers, or restrained from whipping by plant design features, such as concrete encasement, or f
C.
following a single break, the unrestrained pipe movement of either end of the ruptured pipe in any possible direction about a plastic hinge formed at the nearest pipe whip restraint cannot impact any structure, system or component important to f
safety, or e.
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D.
the internal energy level associated with the whipping pipe 1The internal fluid energy level associated with the pipe break reaction may take into account any line restrictions (e.g., flow limiter) between the pressure source and break location, and the effects of either single-ended or double-ended flow conditions, as applicable.
The energy level in a whipping pipe may be considered as insufficient to rupture an impacted pipe of equal or greater nominal pipe size and equal or heavier wall thickness.
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t can be demonstrated to be insufficient to impair the safety functionofanystruckura, system,orcomponenttoanun-
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acceptable level.
II. Design basis piping break locations in the piping systems specified I
under I should conform with the following acceptable criteria:
A.
ASME Section III Code Class 1 piping breaks should be postulated to occur at the following locations in each i
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piping run or branc'h run:
i (a) the terminal' ends, and 3
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l-1 (b) any intermediate locations between terminal ends where i
j the primary plus secondary stress intensities S, (circum-
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f ferential or longitudinal) derived on an elastica 11y I
calculated basis u'nder the loadings associated with one 4
j half safe shutdown earthquake and operational plant 4 exceeds 2.0 S,5 for'ferritic steel, and conditions 7
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Piping is a pressure retaining component consisting of straight or curved -
i i., pipe and pipe fittings (e.g., elbows, tees, and reducers).
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3 A piping run interconnects components such as pressure vessels, pumps and rigidly fixed valves that may act to restrain pipe movement beyond that required for design thermal displacement. A branch run differs from a piping run only in that it originates at a piping intersection, as a branch of the main pipe run.
4Operatienal plant conditions include normal reactor operation, upset conditions (e.g., anticipated operational occurrences) and testing conditions.
5S is the design stress intensity as specified in Section III of the ASME B$ilarandPressureVesselCode,"NuclearPowerPlantComponents."
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2.4 5,for austenitic steel, and
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(c) any intermediate locations between terminal ends where the cumulative usage factor (U) derived from the piping
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i fatigue analysis and based on all normal, upset and t
l testing plant conditions exceeds 0.1, and I
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(d) at intermediate locations in addition to those determined-d i
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i by (b) and (c) above, selected on a reasonable basis as necessary td provide protection. As a minimun, th' era should '
\\1 be two intermediate locations for each piping run or branth run.
- b. ASME Section III Code Class 2 and 3 piping breaks should be postulated to occur at.the following locations in each piping run or branch rue.:
(a) the terminal ends, and (b) any intermediate locations between terminal ends where either the circumfereritial or longitudinal stresses derived on an elastica 11y calculated basis under the loadings
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associated with seismic events and operational.pl' ant con-
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ditions exceed 0.8 (S +S) or the expansion stresses 6U is the cumulative usage factor as specified in Section III of the ASME 3 oiler and Pressure Vessel Code, " Nuclear Power Plant Conponents."
7 is the stress calculated by the rules of NC-3600 and ND-3600 for
.Sh+SA Class 2 and 3 components, respectively, of the ASME Code Saction III Winter 1972 Addenda.
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exceed 0.8 5
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(c) intermediate locations in addition to these determined by 4
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(b) above, selected on reasonable basis as necessary to I
provide protection. As a minimum, there should be two intermediate locations for each piping run or branch run.
III. Pipe break orientation at the break locations as specified under i
II should conform with the following acceptable criteria:
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i longitudinal' breaks in piping runs and branch runs, 4 inches A.
nominal pipe size and larger, and/or 0
B.
circumferential breaks in piping run's and branch runs exceeding 1 inch nominal pipe size.
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8S is the allowable stress range for expansion stress calculated by the A
i rules of NC-3600 of the ASME Code,Section III, or the USA Standard Code for Pressure Piping, ANSI B31.1.0-1967.
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' Longitudinal. breaks are parallel to the pipe axis and oriented at any point around the pipe circumference. The break area is equal to the effective cross-sectional floc area upstream.of the break location.
Dynamic forces resulting from such breaks are assumed to cause lateral
- . pipe movements in the direction nornal to the pipe axis.
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10Circumferential breaks are perpendicular to the pipe axis, and the break area is equivalent to the internal cross-ractional area of the ruptured pipe. Dynamic forces resulting from such breaks are assumed to separate the piping axially, and cause whipping in any direction normal to the pipe axis.
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