ML20211P078
| ML20211P078 | |
| Person / Time | |
|---|---|
| Site: | Brunswick  |
| Issue date: | 07/16/1986 |
| From: | Carfagno D, Carfagno S, Con V, Triolo S CALSPAN CORP. |
| To: | Shaw H NRC |
| Shared Package | |
| ML20211P084 | List: |
| References | |
| CON-NRC-03-81-130, CON-NRC-3-81-130 GL-83-08, GL-83-8, TER-C5506-321, TER-C5506-321-S01, TER-C5506-321-S1, NUDOCS 8607220579 | |
| Download: ML20211P078 (23) | |
Text
.
~
SUPPLEMENTARY TECHNICAL EVALUATION REPORT NRC DOCKET NO, 50-325, 50-324 FRC PROJECT C5506 NRC TAC NO. --
FRC ASSIGNMENT 12 NRC CONTRACT NO. NRC-03-81 130 FRC TASK 321 1
STRUCTURAL EVALUATION OF THE VACUUM BREAKERS (MARK I Cc3TAINMENT PROGRAM) 1j CAROLINA POWER & LIGHT COMPANY BRUNSWICK STEAM ELECTRIC PLANT UNITS 1 AND 2 a
TEli-C5506-321 7
j Prepared for Nuclear Regulatory Commission FRC Group Leader:
V. N. Con Washington, D.C. 20555 NRC Lead Engineer:
H. Shaw r.
l" July 17, 1986 l
J This report was prepared as an account of work sponsored by an agency of the United States iI..
Government. Neither the United States Government nor any agency thereof, or any of their I
employees, makes any warranty, expressed or implied, or assumes any legal liability or responsibility for any third party's use, or the resu!ts of such use, of any information, appa-ratus, product or process disclosed in this report, or represents that its use by such third 9
party would not infringe privately owned rights.
Prepared by:
Reviewed by:
Approved by:
E Mu,,
6 AMM
~-o Pridcipal%bthor
'Departmentpirec ' r 7, /0 /8h Date:
?-U -fk Date: 7' N - b Date:
FRANKLIN RESEARCH CENTER DIVIslON OF ARVIN/CALSPAN 20tn a sact stettis.mnAonmaa.pa tsics l
$bo) 22 09 7%h
~
f o l-TER-C5506-321 CONTENTS Section Title Page 1
INTRODUCTION 1
m 1.1 Generic Background.
1 1.2 Vacuum Breaker Function 2
2 EVALUATION CRITERIA.
9 3
DESIGN LOADS 10 T
b 4
STRESS EVALUATION 11 5
PLANT-SPECIFIC REVIEW: BRUNSWICK PLANT 15 5.1 Background Information.
15 7
5.2 Stress Analysis Results 15 A
6 CONCLUSIONS.
16 7
REFERENCES.
17
,A e
M Ih e
1 I
r iii
O s-TER-C5506-321 FOREWORD This Technical Evaluation Report was prepared by Franklin Research Center under a contract with the U.S. Nuclear Regulatory Commission (Office of Nuclear Reactor Regulation, Division of Operating Reactors) for technical assistance in support of NRC operating reactor licensing actions. The technical evaluation was conducted in accordance with criteria established by L'
the NRC.
I!1 4
3 a
>4 rii WI i
[
I I
'p.
I 1
I f
V
}
f*
(.
f*
TER-C5506-321 1.
INTRODUCTION In a latter state of the generic resolution of the suppression pool dynaric load definition of the Mark I Containment Long-Term Program, a potential failure mode of the vacuum breakers was identified during the chugging and condensation phases of hydrodynamic loadings. To resolve this issue, two vacuum breaker owner groups were formed, one for those with General Precision Engineering (GPE) vacuum breakers, the other for those with Atwood-Morrill (AM) vacuum breakers.
The issue was not part of the original scop'e of the Mark I Containment Long-Term Program as de' scribed in NUREG-0661 [1]. However, vacuum breakers I
have the function of maintaining containment integrity and, therefore, are y
subject to Nuclear Regulatory Commission (NRC) review.
In a generic letter dated February 2, 1983 [E), the NRC requested all affected plants either to submit the results of the plant-unique calculations which formed the bases for modifications to the vacuum breakers or to provide the justification for the as-built acceptability of the vacuum breakers.
~
Franklin Research Center (FRC) has been retained by the NRC to evaluate, the acceptability of the structural analysis techniques and design criteria used in the plant-unique analysis (PUA) reports of 16 plants. As a part of this review, the structural analysis of the vacuum breakers has been reviewed y
and documented in this report.
ll The first part of this report (Sections 1 through 4) consists of generic information that is applicable to all affected plants. The second part of the
~
report (Sections 5 and 6) provides a plant-specific review, which pertains to Brunswick Units 1 and 2 i
1.1 GENERIC BACKGROUND I
I In 1980, the Mark I owners and the NRC became a e of the vacuum breaker damage during full-scale test facility testing and of the potential for damage during actual LOCAs. Two vacuum breaker owner groups, General Precision Engineering (GPE) and Atwood-Morrill (AM), were formed to develop action plan for resolving this issue.
In February 1983, the NRC issued Generic Letter 83-08 [2), requesting commitments from affected utilities to provide
},
TER-C5506-321
(
1 analytical results. The licensees responded to the NRC request by developing appropriate force functions simulating the anticipated hydrodynamic loads, and chen performing stress analyses that used these loads. With respect to loading, the NRC has reviewed and issued a staff position as indicated in Section 3.
FRC's function is to review the stress analysis submitted by a licensee.
L 1.2 VACUUM BREAKER FUNCTION During steam condensation tests on BWR Mark I containments, the wetwell-j to-drywell vacuum breakers cycled repeatedly during the transient phase of steam blowdown. This load was not included in the original load combinations fr used in the design of the vacuum breakers. Consequently, the repeated impact ja of the pallet on the valve seat and body created stresses that may impair its N
capability to remain functional!
A vacuum breaker is a check valve installed between the wetwell and the drywell.
Its primary function is to prevent the formation of a negative pressure on the drywell containment during rapid condensation of steam in the drywell and in the final stages of a LOCA. The vacuum breaker maintains a B.
wetwell pressure less than or equal to the drywell pressure by permitting air flow from the wetwell to the drywell when the wetwell is pressurized and the drywell is depressurized slowly.
A vacuum breaker can be internally or externally mounted. Figures 1 and
]
.3 2 illustrate locations of vacuum breakers.
Schematics of typical GpE and AM vacuum breakers are illustrated in Figures 3 and 4.
A typical pressure differential vacuum breaker during a LOCA is provided in Figure 5.
Table 1 lists tr.e various vacuum breaker types and the plants affected by them.
1
- i,_ _
i.
l.
TER-C5506-321 IN TEAN AL.
Vacuum
~
WETWhL r.,
}
AIRSPACE MAN VEN 7
I U
LRIM(a MEADEA
[
t
.m m.
m
~
OcWNCoMERS
!l TORUS tuPPREnicN PCOL
\\-
?
lI
(
!I l
l Figure 1.
Internal Vacuum Breal:er i'
_3_
e l-TER-CS506-321 External Vacutrn Breaker Q
~
(
I
.a htwell Airspace
[IO min ven k
l
% -Ring Header
}
s U
M 00mers m
7 To m i
Suppression 7
Pool l
T l
I I
Figure 2.
External Vacuum Breaker
, a TER-C5506-321 4
?
,L f
VACW M BRfAFES WALL 8
i
]
].
fh
-m, N__3 ',
o va.
m N
N l
b SE A? etteC i
i j '
+
.q vacuya d
=*"(
SptAPE9 t
(.
,A w s,
%, A, s
's
( C'.0,5 E.C.
-?
L 3 f g.!
PALLE* $?CP
.a RA@t? LA?Of 5 ?'.* C LOCA*lom 14 PLACES.
g,!
J l
6 i
Figure 3.
GPE Vacuum Breaker --,
I TER-C5506-321 2:W.*
T 'b 4e _-
covNTERw1E44 a
iI ex covNrtawt44 5
Lcv tst.
>u I?
iL" J
k'
,. a I
J s
i mME
- a3c, 2
._7_.
s Aes
/
l g
d
\\.
Il
\\
O
\\
\\
s uTERAL DSC. I k
l
~
_ t, scof SEATfEE
,9 g
o y
~
$[o+. b*
\\
e,,
~
ourtaT 6
,w1-g+ %
\\4
.4 T
4
(
\\
-/
t
///viin, /i /,w;,;/ v.;//ui i
t q
2, I
s 9
Figure 4.
Atwood-Morrill Vacuuta Breaker i -.
s.
TER-C5506-321 l-v
?
t-eve WW - tee twe ll DW - Drywell
'I[
t su E
n-e.
I I
6 Chugging Drywell 7
condensation D
4%p
)
gff-De pre s surl a s t ion Oscillations
" Q
";;, n ',,
-~;;a^ - 3 j
j
(
'I Drywell 4
f, Pressurization a
l E
..I F
_ve Time +
4 I
Figure 5.
Typical DW/WW Vacuu:n Breaker Pressure Differential Due to LOCA l - _, _ _ _ _
c
{?
),
TER-C5506-321 j,'
i Table 1.
Vacuum Breaker Types and Affected Plants Vacuum Breaker Plant GPE 18 In (Internal)
Brown Ferry Units 1, 2, and 3 i
Pilgrim Unit 1 Brunswick Units 1 and 2 Cooper Hatch-Units 1 and 2 2
Peach Bottom Units 2 and 3 Duane Arnold
[]
Fermi Unit 2
.J GPE 24 in (Internal)
Hope Creek Ji AM 18 in (Internal)
Monticello Quad Cities Units 1 and 2
- f AM 18 in (External)
Dresden Units 2 and 3
[,.
Millstone Unit 1 Oyster Creek Vermont Yankee AM 18 in (External)
FitzPatrick Nine Mile Point Unit 1 2
l f
)
Y i
! +
-l e
[-
TER-C5506-321 1.
l 2.
EVALUATION CRITERIA To evaluate the design of the vacuum breakers, the affected licensees follow the general requirements of NUREG-0661 [1] and those of " Mark I Containment Program Structural Acceptance Criteria Plant Unique Analysis Application Guide" [3). Specifically, the requirements of the ASME Boiler and Pressure Vessel Code,Section III, Subsection NC for Class 2 Components, 1977 Edition, including the summer 1977 addenda [4], have been used to evaluate the structural integrity of the vacuum breakers.
tn h
ia r it O
b l
J
[
e f
i f,
t
_9_
h*r TER-C5506-321 3.
DESIGN LOADS The loads acting on the Mark I structures and on the vacuum breaker are based upon the Mark I Program Load Definition Report [5] and the NRC Acceptance Criteria [1]. The loads acting on the vacuum breaker include gravity, seismic, and hydrodynamic loads. The hydrodynamic forcing functions were developed by Continuum Dynamics, Inc, (CDI). CDI used a dynamic model of a Mark I pressure suppression system, which was capable of predicting pressure transients at specified locations in the vent system. With this dynamic model and the full-
}l scale test facility data, load definition resulting in pressure differential across the vacuum breaker disc was quantified as a function of time. This
]
issue has been reviewed and addressed by the NRC [6).
d PM
.i I
J WI Mt l
r*
i r
i 4 i
P 4
f TER-C5506-321 4.
STRESS EVALUATION To determine structural integrity of the vacuum breaker, the licensees have employed standard analytical techniques, including the finite element method, to calculate stresses of critical components of the vacuum breaker under various design loadings. Loads resulting from the hydrodynamic phenomenon were compared with those values specified in the ASME Codes (4).
For illustration purposes, a schematic drawing of the moving parts of all components other than the actual disc of the Atwood-Morrill valve and of the qj corresponding finite element model are shown in Figures 6 and 7, respectively.
The model in Figure 7 was used to investigate the dynamic response following 1]
impact.
A typical model for stress analysis of the vacuum breaker disc is shown in Figure 8.
Loading inputs to this'model are the displacement time histories that were obtained from the impact model analysis.
1 J
W e
w PN
>b.
TER-C5506-321 f
a
/- Counte rwe ight Rearing Supports q
J C
N Counterweight Arm Disc Arm
'~% Q2 b.
Shaft E
L'j Counterweight Arm Bolts
- Counterweight
)
Arm Connector
.u 1
I l
Figure 6.
Detailed Valve Internal Model - - - -.
TER-C5506-321
?
COU?iTERWEIGHT 4
N>
I?'TERMEI CHT
- SHAFT 7,
.1 1
J N DISC AR11 t
1 j
- COUl:7ERhTIGHT AP14 CONNECTOR I
f Figure 7.
Finite Element Model of Valve Internals.. _ _
e P.
,f.
TER-C5506-321 l.
MM-t INSIDE DISC SURFACE
,n od P
i.a HUB CONTROL POINT
/
O i
T 2
/
+4 N
nT f
f
/
]
x RIM CONTROL POINT J
f OUTSIDE DISC SURFACE t-
. 1 I
f i
Figure 8.
Valve Detailed Disc Model Geometry I
iw e
f TER-C5506-321 5.
PLANT-SPECIFIC REVIEW: BRUNSWICK d
5.1 BACKGROUND
INFORMATION o
Vacuum breaker type:
18 inch GPE (internal) f Vacuum breakers are located at the vent header / main vent intersection.
o 5.2 STRESS ANALYSIS RESULTS A finite element model of the vacuum breaker was developed using the 1
ANSYS computer program. The stress levels for vacuum breaker critical components were calculated for various pallet impact velocities (Table 2).
An
']b analytical model of the vacuum breaker / vent system fluid dynamics was evaluated [7] to predict the impact velocity of the Brunswick plant. Since q
the stresses are directly proport'ional to the impact velocity, the impact J
velocity for the Brunswick plant was used to scale the stresses in Table 2 to determine vacuum breaker component stresses.
It was decided that since the impact velocity for Brunswick was 5.57 rad /sec, some stresses would exceed allowables and that modifications were required. The modification was a material upgrade to the materials listed in Table 3, which have an allowable stress of 70 ksi.
[
2 4
'f I
o i. - _ _
i, s.
b' TER-C5506-321
~.
t Table 2.
Stress Levels by Component For 18-inch GPE Vacuum Breaker Stress (ksi) for l
Various Pallet Impact Velocities Existing ASME Allowable 3.0 4.5 9.3 Component Materia' Stress (ksi)
(rad /sec) t Pallet SA-516 Gr 70 35.0 21.6 32.4 67.0 Hinge Arm SA-516 Gr 70 35.0 11.8 17.7 36.6 Hinge Shaft SA-320 B8 30.0 19.1 28.6 59.2
'Tj Hinge Arm Stud SA-320 B8 30.0 12.5 18.8 38.8 3
![:
1 2
I I
i if i
l
{
l ' t
7..
![
{
TER-C5506-321 i'
t Table 3.
Higher Strength Replacement Materials For 18-inch GPE Vacuum Breaker Allowable Component Material Stress t-Pallet SA-705 Gr 630 70 ksi (age hardened at 1100*F)
Hinge Shaft SA-564 Gr 630 70 ksi
.l Hinge Arm (age hardened Hinge Arm Stud at 1100*F) a 1
l
[]
~
- []
- t 1
2
' s.
.i
~ f
~!
\\
l 1
C i
g TER-C5506-321 l
r 6.
CONCLUSIONS A review has been conducted to determine the structural integrity of the vacuum breakers of the Brunswick plant. The design loads associated with the hydrodynamic phenomena have been reviewed and addressed by the NRC in i
i Reference 6.
This review covered only the structural analysis of the vacuum breaker, and the following conclusion is drawn from the review:
The analytical methods used to evaluate stresses of critical o
components have been reviewed and judged to be adequate. The stress results exceed allowables; however, the Licensee decided to upgrade h
the vacuum breaker components to the materials listed in Table 3.
This method of modification has been reviewed and found to be adequate.
1 II
[.
.1
'I 1
?
h I
i
- Q' r
1 h
TER-C5506-321 7.
REFERENCES 1.
" Safety Evaluation Report, Mark I Containment Long-Term Program Resolution of Generic Technical Activity A-7," Office of Nuclear Reactor i
Regulation, USNRC
,i.
July 1980 r
2.
D. G. Eisenhut og "USNRC Generic Letter 83-86, Hodification of Vacuum Breakers on Mark I Containment" February 2, 1983 3.
" Mark I Contairunent Program Structural Acceptance Criteria Plant Unique
- f Analysis Application Guide," General Electric Co., San Jose, CA October 1979
' t, q
4.
American Society of~ Mechanical Engineers j
Boiler and Pressure Vessel Code,Section III, Division 1, " Nuclear Power.
Plant Components," New York, 1977 Edition and Addenda up to Summer 1977
'~
5.
NEDO-21888 Revision 2
" Mark I Containment Program Load Definition Report," General Electric Co., San Jose, CA W
November 1981 6.
D. B. Vassallo, NRC Letter with Attachment to H. C. Pfefferlen, BWR Licensing Programs, GE
'I
" Evaluation of Model for Predicting Drywell to Wetwell Vacuum Breaker
~
Valve Dynamics" December 24, 1984 7.
" Improved Dyna:nic Vacuum Breaker Valva Response for the Brunswick Plant,"
Continuum Dyna:nics, Incorporated, Technical Note 82-22 September 1982 I
-