ML19209B853
| ML19209B853 | |
| Person / Time | |
|---|---|
| Site: | Cook  |
| Issue date: | 07/17/1979 |
| From: | Scavuzzo R Advisory Committee on Reactor Safeguards |
| To: | Advisory Committee on Reactor Safeguards |
| References | |
| ACRS-CT-1151, NUDOCS 7910110053 | |
| Download: ML19209B853 (4) | |
Text
.
\\
Cf H51 fB # fM94/1 I
.s l c
.c, 7 >..,..
,..s,n..t a... w -..,5
--___.__.,_m...
Report on the Meeting of July 11, 1979 of the Advisory Committee on Reactor Safety Nuclear Re6ulatory Connission ue n, um c >
3.s r:.
n w,
[L II.
.. a.,iH:s:-
,,gs;9;'ssjJi it~t
(
Ii %uf R. J.V Scavuzio, Ph.D P.
ACRS Consultant July 17, 1979 ti i
I 7 9.1011 cog 3 o
9 C
11'O 140
Combination ofDynanic Loads 1.0 1.1 Introduction The basic purpose of the ACRS meeting held in t
was to review the sta us the afternoon of July 11, 1979, d
in of nethods used for combination of dynamic loa s Specifically seismic analyses.of nuclear cocponents.
the neeting was directed toward the seismic analysis l
b i6 of piping in 14 nuclear plants that used the a ge ra summation method in combininc seismic loans.
1.2 Discussion II.odal forces at a cross section calculated i dynacic analyses v;hich are based on response spectr Signs and phase relation-not be combined algebraienlly.
Signs of forces at ships are lost in response spectra.
depend a particular location are arbitrally assigned and h
upon the normalization process used to calculate t e However, it should be eigenvectors (node shapes).
emphasized that signs of forces within a mode have a specific relationship to each other.
As a result,in order to combine modal forces, P3 moments or stresses at a particular location in ad structure,one of four nethods are usually employe :
(1)
Absolute Sum of Effects Square Root Sum of the Squares (SRSS)
(2) of effects t
})I0 \\'
}
t li *
. a SRSS nethod ncdified to add closely (3) spaced nodal effects absolutely The liRL Sua v;hich adds the SRSS value (4) of all nodal effects except the largest to the largest nodal effect absolutely The 13.0 requires that either nothod 1 or 3 be ative Either of these methods v'till lead to a co used.
analysis of seismic loads.
It has been well documented that piping pumps are systens that do not support large valves or I.any naval vestels have inherently shcck resistant.
to 250 g been shock tected viith g forces in the 50 g Critical range ~;ithout damage directly to the piping.
zle connect-areas are the pipe supports, joints and noz I-This data is consistant vith the presentation j
ions.
nade by Dr. R. L. Cloud.
E I
ConclusionsIf seismic stresses in nuclear piping calculcted 13 l
paced modes using the SRSE nethod accounting for close y s 2C%) away from j~
slightly exceed allowable values (109 to idered nozzles or pipe bends, the systen should be cons j
b Stresses in nozzle. regions and pipe supports G
safe.
Established stress should be critically reviewed.
If a pipe supports a I
limits should not be exceeded.
limits lj large concentrated weight such as a valve, stress
~
r]r should not be exceeded.
Q 11'O 142 M-
3-D. C. Cook Unit 6toan Generater I!ozzle Cracking A number of Westinghouse FJR's reported 2.0 the stean cracking in the 16" main feedwater line near Dr. Zudans suggested ti.at the piping generator nozzle.
between the may be highly stressed from relative motionh feed-steam generator and the other anchor point of t e In the discussion that followed, it was water line.
d by suggested that the relative notion may be cause some type of vibrating motion.
I agree with this content, that this type of king.
vibratory notion nay be the ccuse of the crac notion of the two anchcr points may However, relatit' Both steady state also be caused by thermal expansion.
t up and and transient conditi6ns associated with star died.
po:.er level changes should be thoroughly stu
.g
$u f
v I
h lO 143
^
j r
l-i
!