ML20098B037
| ML20098B037 | |
| Person / Time | |
|---|---|
| Site: | Byron, Braidwood, 05000000 |
| Issue date: | 09/20/1984 |
| From: | Swartz E COMMONWEALTH EDISON CO. |
| To: | Harold Denton Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML20098B038 | List: |
| References | |
| 9216N, NUDOCS 8409250382 | |
| Download: ML20098B037 (5) | |
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N Commonwealth Edison '
f one First National P!ri Chicago. Illinois
(
-- } Addr;ss Reply to: Post Offica Box 767 Chicago, tuinois 60690 q
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September 20, 1984 Mr. Harold R. Denton, Director Office of Nuclear Reactor Regulation U.S.-Nuclear Regulatory Commission Washington, DC 20555 Sub jec t:. Byron Station Units.l.and 2 Braidwood Station Units 1 and 2 Pipe Whip Restraints-Utilizing Crushable Energy Absorbing Material NRC Docket Nos. 50-454/455 and 50-456/457 References (a).
B. J. Youngblood letter to D. L. Farrar dated July 21, 1983 (b):
E. D. Swartz letter to'H. R. Denton dated September 8, 1983 (c):
E. D. Swartz letter to H. R. Denton dated September 7, 1984
Dear Mr. Denton:
On August 29, 1984, a meeting was held in the NRC Region III offices between Region III, NRR, and Commonwealth Edison and our consultant-(Sargent & Lundy) personnel to discuss the remaining NRC concerns with the use of energy absorbing material (EAM) in certain of the pipe whip -restraints utilized at our Byron and Braidwood
. Stations.
At this meeting, the NRC staff requested that we provide a list of all installed pipe whip restraints utilizing a design concept consisting of a single EAM compression member with a single
. tension member, an analysis showing the bounding installation (s),
and the finite element analysis results which demonstrate the-adequacy of design of the bounding installation (s).
The purpose of this letter is to provide this requested information including the list of all restraints utilizing the configuration discussed above, and the results of the detailed nonlinear finite element analysis of the three worst case restraints SI3R-640A, FWR-35 and FWR-16.
A typical restraint using the design concept consisting of a single compression member with energy absorption material (EAM) and a single tension member is shown in the enclosed Figure 1.
In this conceptual design, the pipe whip energy can be absorbed either 8409250382 840920 PDR ADOCK 05000454 I lg A
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by.-crushing-of the EAM or-by-yielding of the tension rod by-adjusting 1the relative. sizes t of the EAM and the necked down area of thei ensioni ar.
When.the pipeLwhip energy is to be absorbed in the t
b a-
-EAM,Lthe: tension rod area is sized large enough not_to yield at the load ltheLEAM crushingcstarts. 'When_the pipe. whip energy is to be-
~ iabsorbed-in the yielding-tension rod, either the EAM is not provided-E Eor-whensprovided.(because of other_-pipe breaks), it is sized large
'enough:notz to~ crush at the~ load magnitude-initiating the yielding of
.the tension 1 rod.-
iThe' enclosed-Table-1 lists.all restraints utilizing the
- singlefcompression~ member.with EAM~and a single-tension member
- concept.
In~this table for'each pipe whip restraint, the angle from
- the/ tension ' leg' toLthe blow down : force direction is listed.
Also J
- listed.isEthe member (tension' leg or compression leg) in'which the pipe whip = energy is being absorbed.
Under:the remarks column,_the 2
- restraints 1which are.no-longer. required _ based on final as built walk
,down.and piping analysis areiidentified.
JThe(tableLlistsf27 tota 1' restraints, 10 of which have been
' deleted.
In 8 of the-remainin'g 17 restraints, the pipe whip energy
~
is?being absorbed _by yielding offthe tension rod without crushing of
.thelEAM. '.Thus,rthe NRC-staff's-concerns on EAM energy absorption
~
- properties ar~e not applicablefto'these restraints.
In 10 of the.17 y
restraints,-theEpipe whip 1 energy is1being absorbed by the EAM fcrushing.. Note restraint RH-R1;is governed by the tension leg'for-
' breaks?2 Land-3,.and by the compression leg _for break 1.-
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_ !In Referencer(a), the:NRC staff stated, "The staff believes Lthat the-tension = member ~for two. restraints.(identified ~as'FWR-35 and
- SI3R-640A).~willsbe in compression (not; tension) during the initial
~
loadingiphase. -Consequently,.the EAM willi be subjected to a load
- angularityfan'd< deformation not-explicitly considered in the
_Lrestraint-design.nor in the-test plan.
Furthermore,.the-EAM will be-subjected to an additional bending moment'(in ~ conjunction with the
~
compressive and lateralL loadings) which is.also not considered in Ethe~ restraint 1 design nor in'the test. plan." ~(Reference (b) stated ithelCommonwealth Edison position that it was not possible for LHexcel/ MCI to perform =a dynamic test to simulate-the FWR-35
. restraint design utilizing the existing-test configuration.)
This
' LNRC"staffiabservation 'was based Ron the fact 'that the angle between (theitension legLand the; blow down. force direction for these two 1:
l restraints:was less thanL900..
i,_,
. _.In; response to the NRC staff's concern, we have performed a
-detailedJfinite element nonlinear, large deflection analysis of pipe
.~
(whip 4 restraints F.WR-35, SI3R-640A, and FWR-16.
FWR-16 was added to itheili'stLof.~ restraints ~because'it is the third worst case restraint fromLthe load: angularity' criteria as shown in the enclosed Table 1.
=As1 stated:during.theJAugust. 29, 1984 meeting,-both FWR-35 a'nd-FWR-16
'have;been' deleted andfare no longer required.
The analysis model and resulting responses are summarized in the attached SAD Report 442_ entitled, " Finite Element Analysis of Pipe Whip Restraints SI3R-640A, FWR-35 and FWR-16".
In this
, analysis, possible buckling of the tension rod and the direct compression with shear'and bending moment on the EAM is considered.
This analysis shows that the maximum strain.in the-EAM is less than 21% for the three cases.
The deformed shape of the EAM is also bounded by the.EAM. deformation achieved in the Byron Station
' impact.. loading in angularity configuration tests.
In addition, this
-analysis.also shows that_the tension leg is in tension at all levels of load and the question of buckling of the tension rod does not arise.- Based on the results of the detailed nonlinear finite element analysis of the three worst case restraints, it is our conclusion that the Byron and Braidwood Station pipe whip restraint.
design-is conservative _and that these restraints will perform their intended function.
Reference (c)'provided the simplified sketches for the 79 Sargent & Lundy and 23 Westin~ghouse designed pipe whip restraints as also-requested during the August 29,-1984 meeting.
Our response to the; remaining open items identified and discussed during the meeting
.is currently undergoing-our final review and will be provided early next week.
One signed original and fif teen copies of this letter with
-the_ Enclosure are provided for your use.
Additionally, this information package is being sent directly to Region III.
Very truly your
/
ep-E.
buglas Nuclear Licensing Administrator Enclosure EDS/ rap-t cc:
J. A. Stevens - LB1 J.'Streeter --RIII
'9216N
- s TABLE la LIST OF PIPE WHIP RESTRAINTS WITH A SINGLE EAM COMPRESSION MEMBER AND WITH A SINGLE TENSION MEMBER PIPE WHIP ANGLE FROM TENSION LEG YIELD IN COMPRESSION RESTRAINT NO.
TO BLOW DOWN DIRECTION OR TENSION LEG (*)
REMARKS 0
FWR-3 107 C
0 FWR-4 109 C
DELETED 0
FWR-6 90 C
DELETED 0
FWR-12 110 T
0 FWR-13 121 T
DELETED 0
FWR-16 91 T
DELETED 0
FWR-25 102 T
DELETED 0
FWR-27 109 T
DELETED FWR-30 112 T
DELETED 0
FWR-31 135 T
FWR-35 78 C
DELETED FWR-36 106 T
DELETED FWR-38 107 C
DELETED 0
FWR-39 111 T
0 MS-P10 164 T
0 MS-P25 168 T
MS-R1 133 C
0 MS-R2 135 C
MS-R9 135 C
MS-R10 131 C
0
'MS-R11 135 T
MS-R49 135 T
0 SIlR-10B 122 C
0 SI3R-640A 84 C
0 SI4R-15B 92 C
RH-R1 (BRK-2, 3) 135 T
0
~RH-R1 (BRK-1) 113 C
0 RH-R3 116 C
- T = Tension Leg j
C = Compression Leg
%" ~tRING EL. 40l'- 5 /s" 8
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%. PIPE} _
f
[ RING
( 8",
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- t I" x IO"(TYP.)
I k I" L 3 / " x 71/ " x l'-O" 1
L 2 / " x II" x l'-O" -
k 2
2 i
8 4
7 '/ "
L 2 / " x II" x l'-0" 1
2 4
-HONEYCOMB MATERIAL h
l 5
4 /s" x 9" x ll" I~ 2'/ GA. Al93-B7 M
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HE NUT A 4 2 8
5 w/ 2 / " DIA. UPSET ENDS i
10 4
1 3
t I" x 3 / " x l'-3 / "
2 2
3'/ "
2 t I" x 12" (TYP.)
L 3 / " X 7'/ " x l'-0" 3
9 2
2 3
3 L I" x 4 / " x O'-7" 2
L IN PLACE i IN PLACE
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y.3j.j 4'-34s" TYPICAL WHIP RESTRAINT UTILIZING TENSION-COMPRESSION MEMBER CONCEPT FIGURE i