ML19319D511
| ML19319D511 | |
| Person / Time | |
|---|---|
| Site: | Crystal River  |
| Issue date: | 07/13/1973 |
| From: | US ATOMIC ENERGY COMMISSION (AEC) |
| To: | |
| Shared Package | |
| ML19319D504 | List: |
| References | |
| NUDOCS 8003170637 | |
| Download: ML19319D511 (4) | |
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Attachment B w1:Li MEB REGULATORY POSITION
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1.5 PIPE In!IP ANALYSIS w
f Analyses are required to effects of postulated design basis becaks within containmentsu
'j impact or overstress any structures, systcas or component will not
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to safaty to the extent that their safety functi n i l,(
s important precluded.
the resulting loadings in terms of:The analysis methods used should s impaired or o
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,gg m ne the kine' tic energy or momentum induced by the impact a,
qgg pipe, if unrest tant to safety, rained, on a, protective barrier or a componentof the whipping t
j impor-h3 b,
the dynamic response of the restraints in'duced b L,
rebound if any, of the ruptured pipe.
y the impact and 1:
A m.,
The basis used to determine che magnitude of jet
.j in dynamic analysis should be provided thrust force as required h
6 The methods of dynamic analysis specified in II and III y
provided the following associated criteria are met:
are acceptc$le
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I.
Pipo ilhlo Dvnnmic Analvsic Criteria An analysis of the pipe run er brant; D cod D
q"-
o a.
3 g
j ey, add 9m desian basis break locations,cach lcagitudinal and circumf the b.
The loading condition of a pipe run or branch prior t rupture in terms of internal pressure, I
o postulated condition (normal and upset), state should be those conditi r operating For a circumferential rupture, pipe whip dynamic an l c.
'which is connected to a contained fluiJ cncray a ysis need ranch a sufficient capacity to develop a jet eservoir having stream.
d.
Dynamic analynts method.s uced for calculating the pi i piping / restraint p ng or system response to the jet following postulated rupture should adequately account fthrust d effects of:
or the (1) mass inertia and stiffness properties of the system,
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a sw
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h.
.x r,
t t
1 i
h (2) impact and rebound (if any) cffects as permitted by gaps between piping and restraint,
. eR (3) clastic and inclastic deformatidn of piping and/or restraint
[.i and
_F2 (4) limiting boundary conditions.
c.
The allowable design strain limit for the restraint should not exceed 0.5 ultimate uniform strain of.the materials of the restraints. The nethod of dynamic analysis used should be capabic of de craining tne inelastic behavior of piping-restraint h}
system response within.these design limits.
Q k_
f.
A 10% increase of minimum specified design yield strength (S )
y
=ay be used in the analysis to account for strain rate effects.
g.
Dynamic analysis methods and procedures.should consist of:
U' a representative mathematical model of the piping sys ca n
or piping / restraint systc=,
Q (2) the analytical acthod of sblution selected, i,
(3) solutions for the most severe response among the design bisis breaks analyzed, (4) solutions with dc=onstrabic accuracy or justifiable conservatisa.
h.
The c>: tent of mathematical ecdeling and analysis should be governed by the method of analysis selected among those specified by these Il Criteri u.
w=
II.
Acceptable Dynamic Analysis for Restrained Pipine Systems 8
Accept:ble Models for Analysis for ASME Class 1, 2 and 3 piping a.
systems are:
I,.
(1) Lumped-Parameter Analysis Model; Lumped cass points arc inter-connected by springs to take into account inertia and stiffness effects of the system, and time histories of responses are
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computed by nu=crical integration to account for gaps and in-t ciactic effects.
(2) Energy-Balance Analysis Model; Kinetic energy generated during the first quarter cycle covement of the ruptured pipe as in-
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parted to the piping /rcstraint system through impact is convertog 7:
into equivalent strain energy. Defor=ations of the nigejgEd).thek N
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@BDD I
e
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~~=...~=-*,....-,..,c-. -. =. - -
7..a7- -
.m.
x...-
c s
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---w-
"d
,j p
a e
,q g
(
-o s
3-l restraint are compatibic with the icvel of absorbed energy.
For applications where pipe rebound may occur upon impact on the restraint an additional amplification factor of 1.5 should E
be used to establish the ma:;nitude of the forcing function in
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order to determine the maximum reaction force of the restrainc
]
after the first quarter cycic of.rcsponse.
Amplification i
factors other than 1.5 may be used if justified by more detailed dynamic analysis.
(3) Static Analysis Modal - The jet thrust force is represented by a conservatively amplified static loading, and the ruptured i..
' system is analyzec statically. Tac amplification f:.ctor used to establish the magnitude of the forcing function should be g
based on selection of a conservative value as obtained by g
comparison with the factors derived from detailed dynamic I
analysis performed on'comparabic systems.
III.
Acceptable Dynamic Analysis for Unrestrained Pipe '# nip a.
Lumped-Parameter Analysis Model as stated in 11.a(1) is acceptrble.
a b.
Energy-Balance Analysis Model as stated in II.a(2) is acceptabic.
e The energy absorbed by the pipe deformation may be dedue cd from L
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the total energy impa ted to the system.
c.
_ The assumptions used to guide the mechanism of pipe movenent should be justificu to be conservative.
d.
The results of analysis should be expressed in terms compatibic with the approach used for verifying the design adequacy of the q
impacted structure.
IV.
Flow Thrust Force a.
The time function of the thrust force induced by jet flow at the design basis pipe break location should consider:
(1) the initial pulse, (2) the thrust dip, and (3) the transient function.
L b.
A steady state forcing. function can be used when conditions as l
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specified in c'bclow are met.
The function should have a magnitude not less than.
[-
I T-nA p
l t
"-M O
W 9
4 D
n : = 2 :-- :
=
= --
x..y Q.
g p
- s **
V i
j sf'
- a,.
l, s
a i
.i where i
p = system pressure prior to pipe break
'N A = pipe break arca, and -
h K - thrust coefficient.
Acceptable K values should not be less than the following:
(a) 1.26 for saturated steam, water and stec=/ water sixture (b) 2.00 for subcooled water-nonflashing.
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4
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c.
A pulse rise. time not, exceeding one millisecond should be used.
f for the initial pulse,'unless longer crack propagation times or
)
rupture opening times 4can be substantiated by experimental data or analytical theory.
t d.
The transient function should be provided and justified. The shape cf the transient function, IV a. (3) above. should be related.co the capacity of the upstres= energy reservoir, including source pressure, fluid enthalpy, and the capability of the reservoir 7;
to supply high energy flev stream to the break area for a significant ll interval.
The shape of the transient function ny be modified by considering the break area and the syste. flow conditions, the h
piping friction losses, the flow directional' changes, and the,.
application of Llow limiting devices.
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e.
The jet thrust force ay be repreco". ed by a steady state function, b above, provided tha following conditicas are cet:
o a'.
(1) The-transient function, IV a. (3) above, is conoconically L
di=inishing.
t
=
(2) The energy balance nedel or the static codel is used in the analysis.
In the former case, a step function amplified to the magnitude as indicated in II.a(2) is acceptabic.
(3) The energy approach is used for the i= pact effects of the j
unrestrained piping.
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