ML20072E976

Forwards Results of plant-unique Calculations Which Form Bases for Mod Program in Response to Generic Ltr 83-08, Mod of Mark I Containment Vacuum Breakers

ML20072E976
Person / Time
Site:	Brunswick
Issue date:	06/23/1983
From:	Zimmerman S CAROLINA POWER & LIGHT CO.
To:	Vassallo D Office of Nuclear Reactor Regulation
Shared Package
ML20072E980	List: ML20072E976 ML20072E982 ML20072E995
References
REF-GTECI-A-07, REF-GTECI-CO, TASK-A-07, TASK-A-7, TASK-OR GL-83-08, GL-83-8, LAP-83-254, NUDOCS 8306270225
Download: ML20072E976 (85)

Text

,..

SERIAL: LAP-83-254 Carolina Power & Light Company JE 231983 Director of Nuclear Reactor Regulation Attention:

Mr. D. B. Vassallo, Chief Operating Reactors Branch No. 2 Division of Licensing United States Nuclear Regulatory Commission Washington, DC 20555 BRUNSWICK STEAM ELECTRIC PLANT, UNIT NOS. 1 AND 2 DOCKET NOS. 50-325 AND 50-324 LICENSE NOS. DPR-71 AND DPR-62 RESPONSE TO NRC GENERIC LETTER 83-08 MODIFICATION OF MARK I CONTAINMENT VACUUM BREAKERS

Dear Mr. Vassallo:

By letter dated May 19, 1983 (Serial No. LAP-83-148), Carolina Power & Light Company (CP&L) responded to Generic Letter 83-08 dated February 2, 1983 concerning modification of vacuum breakers on Mark I containments. As requested by Generic Letter 83-08, CP&L committed to submit by June 30, 1983 the results of plant unique calculations which formed the bases for our modification program. To fulfill this commitment, CP&L herewith provides one copy of the following documents:

1.

" Mark I Vacuum Breaker Improved Valve Dynamic Model - Model Development and Validation," Continuum Dynamics, Incorporated, Technical Note 82-31, September 1982.

2.

" Improved Dynamic Vacuum Breaker Valve Response for the Brunswick Plant," Continuum Dynamics, Incorporated, Technical Note 82-22, September 1982.

3 Applicable sections of "GPE Vacuum Breaker Modification Program Phase II Final Report," NUTECH Engineers, MKI-05-045, October 1982.

If you have any questions concerning this submittal, please contact our staff.

Yours very truly, 8306270225 830623 S. R.

immerman PDR ADOCK 05000324 P

PDR Manager Licensing & Permits WRM/cfr (7132WRM)

f. F[

Enclosures o

cc:

Mr. D. O. Myers (NRC-BSEP) k)

Mr. J. P. O'Reilly (NRC-RII)

Mr. S. D. MacKay (NRC) 411 Fayetteville Street

• P. O. Box 1551

• Raleigh, N. C. 27602

e ABSTRACT During the Full Scale Test Facility (FSTF) steam condensation tests performed as part of the Mark I Containment Program, a GPE wetwell-to-drywell vacuum breaker cycled repeatedly during the chugging phase of steam blowdown.

The vacuum breakers were not originally designed for such cycling, nor the resulting impact of l

the pallet on the valve seat.

The GPE Vacuum Breaker Modifica-tion Program was established to address this issue.

i Phase I of tb's GPE Vacuum Breaker Modification Program investi-gated a number of alternative approaches to mitigating vacuum I

breaker cycling and selected a concept for reducing pallet impact velocities.

Phase I was completed in 1981 and concluded that a snubber device was the most practical means of limiting pallet impact velocities.

The purpose of Phase II of this program was to design, analyze, and test a prototype of the modification to demonstrate the feasibility of the concept.

Phase II also evaluated _ impact velocity predictions obtained from improved fluid dynamic modeling performed by Continuum Dynamics, Inc.

l

( CDI).

l l

l This report presents the results of all the activities of Phase j

II of the GPE Vacuum Breaker Modification Program. The prototype modification has been demonstrated to substantially reduce impact i

velocites during chugging.

The improved CDI impact velocity i

I MKl-05-045 iii Revision 0 i

I l

l predictions are also evaluated and recommendations are made for modifying the GPE Vacuum Breakers carrently in Mark I plants.

In light of the reduced impact velocities predicted by CDI, replacement of the critical vacuu'm breaker parts with materials of increased strength will be sufficient to permit the valves to meet design requirements.

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1.0 INTRODUCTION

Facility (FSTF) steam conden-During the Full Scale Test sation tests performed au part of the Mark I Containment Program (Reference 1) a GPE wetwell-to-drywell vacuum breaker cycled repeatedly during the chugging phase of The vacuum breakers were not originally steam blowdown.

nor the resulting impact of desig'ned for such cycling, Gasket foldover also the pallet on the valve seat.

occurred during cycling.

The GPE Vacuum Breaker Modification Program was estab-lished to improve the performance of the GPE vacuum impact breakers during chugging by reducing the pallet flange and by eliminating gasket velocity at the front foldover.

To meet the objectives, the program was divided into three phases.

Phase I Evaluate and select a modification concept.

Phase II Design, analyze and test the modification.

Design an improved pallet gasket.

Evaluate CDI pallet impact velocity predictions.

f 1.1 MKl-05-045 Revision 0

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e Phase III Implement the plant modification.

Phase I is reported in Reference 2, while the results of Phase II are presented in this report.

Phase III is a plant unique activity and is not addressed in this report.

1.1 Background

b In Mark I plants the GPE wetwell-to-drywell vacuum breakers are located inside the wetwell, cantilevered from the main vent header.

Figure 1.1-1 illustrates their relative position inside the Mark I Containment.

In Fi ure 1.1-2, a schematic of the unmodified GPE vacuam breaker is shown.

The vacuum breaker is basically a check valve permitting air to flow into the drywell only.

During a postulated Loss-of-Coolant-Accident (LOCA) the vacuum breaker will be exposed to a drywell/wetwell pressure differential as shown in Figure 1.1-3.

This transient comprises a number of different phenomena.

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Drywell pressurization is the first phase of the LOCA.

During this phase, the vacuum breaker pallet remains MKl-05-045 1.2 Revision 0 t

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shut as the drywell is filled with steam following pipe rupture.

Steam travels through the main vent, ring l

i header, and downcomers and is condensed in the suppression pool.

t In the second phase, called condensation oscillation, the discharge of steam into the suppression pool at a relatively high pressure produces pressure oscillations I

in the pool and vent system.

During this phase, the differential pressure across the vacuum breaker pallet Y

i L is sufficient to keep the pallet closed.

t The third phase of the LOCA is the chugging phase.

Steam condensation during this phase is characterized by movement of the water-steam interface in the downcomer.

It is during this chugging phase that the l

wetwell-to-drywell vacuum breaker may cycle due to the g

oscillating pressure across the pallet.

The fourth and final phase is drywell depressurization.

During this phase of the LOCA, the vacuum breakers open to limit the negative pressure differential on the drywell and vent system caused by rapid steam condensa-tion in the drywell.

MKl-05-045 1.3 Revision 0

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VACUUM l

BREAKER i

TO DRYWELL WETWELL

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MAIN VENT l

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W S UPP RESSION POOL FIGURE 1.1-1 LOCATION OF MARK I GPF WETWELL-TO-DRYWELL l

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FIGURE 1.1-2 N

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i UNMODIFIED 18-IMCH GPE VACCUM BREAKER

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DRYWELL CONDENSATION DEPRESSURIZATION OSCILLATIONS CHUGGING 5

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DRYWELL PRESSURIZATION in m

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FIGURE 1.1-3 TYPICAL PRESSURE DIFFERENTIAL ACROSS VACUUM BREAKER DURING LOCA MKl-05-045 1.6 Revision 0 l

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1 1.2 Results of Phase I

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.a Phase I evaluated various concepts for reducing the effects of chugging on GPE vacuum breakers.

Reference 2 summarizes the Phase I effort.

This investigation

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showed that if replacement of critical components with

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higher strength materials did not result in acceptable I

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stress levels during chugging, installation of a snubber device to limit impact velocity would be the most

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t 1.3 Phase II I

i identified and In Phase II, two parallel efforts were One effort was to design, analyze, and investigated.

This included test a prototypical snubber modification.

fabrication of a ring-stiffened pallet gasket.

the j

Phase II also evaluated impact velocity predictions l}

obtained from improved fluid dynamic modeling performed i'

Inc. (CDI).

Included in this by Continuum Dynamics, i-for modifying GPE vacuum evaluation are recommendations in Mark I plants based on the CDI predictions.

breakers

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a 1.4 Phase III the implementation of any needed i

Phase III involves Phase III is a plant vacuum breaker modifications.

i addressed in this report.

unique activity and is not n

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3.4 Stress Analysis of the 18 and 24-INCH GPE Vacuum Breakers I

The finite-element stress analyses of the 18 and 24-inch

.I GPE vacuum breakers were carried out during the Short Term Program describcd by References 4 and 5.

In that program, a finite element analysis was performed using the computer program ANSYS.

This analysis showed that stress is a linear function of pallet impact velocity and that the impact is elastic for velocities in the range occurring in Mark I vacuum breakers.

Figures 3.4-1 and 3.4-2 show the finite element models.

A plate element was used to model pallet response and a beam element was used for the shaft and hinge arm 1

1 del-05-045 3.5 Revision 0 1

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assembly.

Because of symmetry, only half of each lI assembly required modeling.

l Since the response was elastic, the analysis could be i

performed for one.value of the impact velocity and then scaled linearly to obtain the stresses at other values of impact velocity.

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FIGURE 3.4-1 CRITICAL STP.ESS PLANES FOR COMPUTING PALLET STRENGTH FOR IMPACT WITH FLANGE MK1-05-045 3.7 Revision 0

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DISPLACEMENT 7

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1. DISPLACEMENT AND ROTATION TIME HISTORIES IMPOSED AT NODE 7 OBTAINED FROM DETAILED

>3 PALLET MODEL.

2. ALL DEGREES OF FREEDOM COUPLED 5 rff BETWEEN NODES 6 AND 4 EXCEPT ROTATION ABOUT X AXIS.

FULL RESTRAINT ANALYTICAL MODEL a.

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DETAILED VACUUM BREAKER HINGE MODEL

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3.5 Gasket Modification i

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s s %.. During the FSTF tests, it was observed that the pallet i._ %%

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the pallet and the front flange of the vacuum breaker.

To prevent fold over the gasket was redesigned to-

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g the gasket.

This involved designing a sandwich gasket

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with two outer layers of' ethylene propylene (EPDM)

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i enclosing ;t. st.ainless steel ring of eighteen (18) gauge jl x

material.

This redesigned gasket is much stiffer than 2

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In Appendix A, Figure A-5

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illustrat'es the redesigned gasket.

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J 4.0 UNMODIFIED GPE 18-INCH VACUUM BREAK'R,, TESTS Simplifying assumptions were used to reduce the com-p3exity of the mathematical models developed to predict the

dynamic response and resultant stress levels of the unmodified vacuum breaker during chugging.

At' the request of the GPE Owners Group, tests.with an unmodified GPE vacuum breaker were performed to l

+

determine the accuracy of the results cbtained from these'models.

To comply with this request, a simple drop test of the vacuhm breaker pallet was devised, and the closing impact velocities and stresses were measured.

This section describes the unmodified vacuum breaker tests and presents the test results.

Section 6 compares the test results with the analyses.

I I

4.1 Purpose of Test Analytical investigations of the stress levels in the l

moving parts of GPE vacuum breakers exposed to postulated chugging loads were perfor.ned using two mathematical models.

The first model was designed to predict the dynamic response of the vacuum breaker pallet to the chugging loads.

This model was used to MKl-05-045 4.1 Revision 0 L

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predict the impact velocity of the pallet on the front flange of the vacuum breaker.

It is this impact velocity which determines the peak stresses in the

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P moving parts of the vacuum breaker.

A sophisticated i

finite element model of each component was also i

developed for input to the ANSYS computer program in g

l order to predict the stress levels.

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f A simple drop test of the pallet under the force of gravity is sufficient to produce impact velocities in j

the range of the' levels predicted by the improved CDI I

methods.

This test was carried out, and excellent 1

agreement was found between analysis and the test results.

4.2 Test Description i

Since impact stresses in the moving components of the vacuum breaker valve are proportional to the impact velocity, a simple pallet drop test was devised to

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obtain stress versus impact velocity data for various values of impact velocity.

Results obtained from the analytical models predicted that pallet drop tests using inclination angles up to 64* from vertical would result

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in stresses below the material yield stresses.

Based on i

l these results, it was decided to perform the pallet drop

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MK1-05-045 4.2 Revision 0

a inclination angles of 10*,

20*,

30*,

40*,

50*,

tests at and 64* from vertical.

It should be noted that the pallet is at an inclination of 4* from vertical when in the closed position.

The drop tests were performed by raising the pallet to to fall freely the desired angle and releasing it The against the front flange of the vacuum breaker.

process was repeated for each of the specified angles.

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4.3 Test Instrumentation II instru-Figure 4 3-1 shows a schematic of the test mentation, exclusive of strain gauges.

The angle of inclination of the pallet relative to the vertical was g

measured by an inclinometer attached to the center of i

I the pallet.

The location of the inclinometer is shown in Figure 4.3-1.

I A velocity proximity probe was located near the bottom of the pallet, in the vicinity of the front stops.

Its to accurately measure the approach and purpose was rebound velocities.

This information was required in of restitution, order to calculate the coefficient

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4.3 MKl-05-045 Revision 0

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which, in turn, was needed for the analytical modeling of the phenomenon.

The pallet was instrumented with three 45* strain rosettes attached at the locations indicated in Figure 4.3-2.

No attempt was made to find the peak stress, although the strain gauges were located close to points of peak stress.

The primary intent was to locate the strain gauges in order to measure the trend in pallet stresses which would be compared with analytical predictions.

If the-analytical model could predict the measured stresses accurately, it would also predict peak stresses accurately.

The stress values given in Figure 4.3-2 correspond to an impact velocity of 25.0 radians /sec.

H Instrumentation for the shaft consisted of two uniaxial i

l strain gauges welded 90* apart.

Analysis had shown tnat t

the significant stresses were caused by the shaft bending.

Because of symmetry, the maxiraum point of i

,' l bending occurs at the middle of the shaft.

Figure 4.3-3 illustrates the locations of the strain gauges on the p

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shaft and hinge arm.

A complete list of test instrumentation is presented in Table 4.3-l'.

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TABLE 4.3-1 a

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I' INSTRUMENTATION _

i l TEST uniaxial strain gauges Four(4) o rosette strain gauges Three(3) k o

Eighteen-channel wheatstone bridge non-contacting proximity probe o

a One(l) 7 o

i Fourteen-channel FM tape recorder e

o GenRad minicomputer system 4

o Oscillocope o

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PIVOT POINT

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VELOCITY J

PROXIMITY PROBE

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'I 17ACUUM BREAKER TEST INSTRUMENTATION t

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t FIGURE 4.3-2 1, 2, AND 3 LOCATION OF STRAIN GAUGE ROSETTES ON OUTSIDE SURFACE OF PALLET _

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1 SECTION A-A FIGURE 4.3-3 UGES LOCATION OF SHAFT AND HINGE STRAIN GA l

1A, 1B, AND 2A, 2B_

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pata Accuisition System 4.4 1

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the components of the data acquis -

Figure 4.4-1 shows l

The strain gauges are connected to signa l

i tion system.

in strain gauge change conditioners which convert the is recorded on This voltage resistance to a voltage.

it and in addition,

record, tape to obtain a permanent A computer program is read into a GenRad minicomputer.

into principal (strain reading) converts the voltage stresses.

i' ll of the The GenRad minicomputer did virtually a i

tests.

This required data collection for the dynam c up for real time acquisition set minicomputer system is l

to for up to four channels with an internal ana og floppy The system uses magnetic digital converter.

for data for storage and is programmable disks for data it was also used Therefore, manipulation.

l Data can be represented as both an ana og redaction.

listing of the elements making up graph or a digital that block of data.

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4.5 Test Procedure fixture is shown in Figure 4.5-1.

This steel The test fixture supported the vacuum breaker in the same manner in which it is supported in the Mark I containment.

i The dynamic impact test consisted of dropping the valve f

4 pallet from several open positions, namely 10' increments starting from 10*.

Table 4.5-1 presents i

stress as a function of impact velocity.

The maximum stress was expected to occur at an impact velocity developed by a 60* opening angle.

Care was exercised for each test so that the yield stress in each component part was not exceeded.

The maximum impact velocity during the test was about 6.0 rad /sec.

A detailed description of the test procedures is provided in Reference 6.

1 consisted of opening the valve The execution of the test ll to the desired position.

This was done using a come-i along (see Figure 4.3-1).

After the valve was opened to position, the tape recorder was activated.

The signal to release the electromagnet, thereby releasing the l

valve pallet, began the test.

The readings from the strain gauges and the proximity probe were recorded on f-tape by the GenRad minicomputer.

The proximity probe

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channels of the strain gauges were routed and three (3) i At to the minicomputer for storage and data reduction.

'i the same time, strain information from the vacuum i

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breaker shaft and pallet hinge arm was recorded.

l, h-data was later processed to obtain the maximum averaged I[

stresses.

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7 TABLE 4.5-1 LEVELS BY COMPONENT _

STRESS FOR 18-INCH GPE VACUUM BREAKER _

STRESS (KSI) FOR VARIOUS PALLET L

IMPACT VELOCITIES 3.0 4.5 9.3 ASME ALLOWABLE (rad /sec)

EXISTING STRESS (ksi)_

MATERIAL _

COMPONENT _

i 21.6 32.4 67.0

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35.0 SA-516 Gr 70 Pallet

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i 11.8 17.7 36.6 35.0 SA-516 Gr 70 Hinge Arm 19.1 28.6 59.2 30.0 SA-320 B8 Hinge Shaft a

12.5 18.8 38.8 30.0 SA-320 B8 Hinge Arm Stud 1

velocity for all 1

is a linear linear interpolation of the above function of impact stress Note:

Stress Thus components.

values can be applied, i

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1 4.13 MKl-05-045 Revision 0

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TEST SUPPORT FIXTURE

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FIGURE 4.5-1 TEST FIXTURE USED FOR PALLET DROP TEST

1 MKl-05-045 4.14 Revision 0

Data Reduction 4.6 reduced to analog and digital The acquired data was In the case of the strain listings of time-histories.

s time.

the listings consisted of strain versu

gauges, listings consisted of the For the proximity probe, Typical stress outputs are shown distance versus time.

in Appendix B.

4.7 Test Results_

odified This section describes the results of the unm

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vacuum breaker tests.

Impact Velocities 4.7.1 the relationship between the pallet In Figure 4.7-1, impact velocity is shown.

angle of inclination and the series of from the first The data points were obtained fitted to the test data was The line drop tests.

squares.

calculated using the method of least Hinge Stresses 4.7.2 i

right angles to one strain gauges at Two uniaxial located on the pallet hinge arm (see another are h

4.15 MKl-05-045 Revision 0

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Figure 4.7-2 shows the combined stress 0

Figure 4.3-3).

i 2A and 2B, measured by gauges the test curve can be seen that From Figure 4.7-2 it xes.

does not go through the origin of the coordinate a I

i the strain gauges is due to the fact that This effect llet removed were calibrated to zero stress with the pa

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When the pallet was replaced from the vacuum breaker.

its dead weight produced a small in the vacuum breaker, the tests were performed with the Subsequently, stress.

A corrected curve, hinge having a small initial stress.

d, is also the initial stress having been subtracte presented in Figure 4.7-2.

i 1

4.7.3 Pallet Stresses for the outside 1

Figure 4.7-3 shows the test results The stresses are the maximum surface of the pallet.

from the Distances are measured principal stresses.

i of the pallet along Section A-A shown in F gure midpoint 4.3-2.

4.7.4 Shaft Bending Stresses i

shows the location of two uniaxial stra n 2

Figure 4.3-3 and ninety the center of the shaft located at gauges 4.16 MK1-05-045 Revision 0 l

.I degrees apart circumferentially.

This configuration j

permitted calculation of the maximum bending stresses from the strain gauge data.

In Figure 4.7-4, a plot of the test results is shown.

4.8 conclusions that of linearity The key assumptions of the analysis, for material behavior and selection of boundary to be very accurate based ca the conditions,.nppears the test results test results.

Chapter 6.0 compares with the results of analysis.

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. U U.*

<t 2-me g78 3

gg 1-e Data Points

.D b

10 20 30 40 50 60 70 80 INITIAL POSITION (Degrees from Vertical)

W t.

FIGURE 4.7-1 IMPACT VELOCITY VERSUS INITIAL PALLET OPEN ANGLE i

I i

MKl-05-045 4.18 Revision 0

OPEN ANGLE (Degrees) 12.7 24.5 48.0 60.0 71.5 12.5 -

i 10.0 -

?

CORRECTED TEST DAT.A

7. 5 -

s Ea r.a y

5. 0 -

z I

2. 5 -

e COMBINED TEST RESULTS (SRSS) f E CORRECTED TEST DATA 0

p 0

1 2

3 4

5 l

t IMPACT VELOCITY (Radians /Second) 1 1

FIGURE 4.7-2 f

HINGE STRESS VERSUS PALLET IMPACT VELOCITY l1 MKl-05-045 4,19 l

Revision 0 i

w 3

I c

liil l

l 1

il l

pl 9

B l

L i

i l

l l

5

(

l 40-I A EST ESUMS 30 -

i.

I 1

1 l

i 20 -

1 n

r usx w

10 -

e un 9

E

=

0--

2 4

6 8

10 12 DISTANCE FROM CENTEPLINE (inches) rad TEST IMPACT VELOCITY = 5.0 sec

-20 16

'l ll l

l lr b

1 FIGURE 4.7-3 6

PRINCIPAL STRESS MEASURED ALONG 6

SECTION A-A OF PALLET i

{

I i

MKl-05-045 4.20 Revision 0 io

OPEN ANGLE (Degrees) j 0

10 20 30 40 50 60 70 I

t t

t t

I f

)

a 40 -

35 -

30 -

C jl 25 -

m

=

m 20 -

15 -

10 -

1 5-e TEST DATA i

0 j

0 0.77 1.62 2.47 3.32 4.17 5.02 5.78 IMPACT VELOCITY (Radians /Second)

I FIGURE 4.7-4 SHAFT BENDING STRESS VERSUS PALLET OPEN ANGLE AND D1 PACT VELOCITY MKl-05-045 4.21 j

Revision 0 l

3

)

6.' O COMPARISON OF TEST RESULTS AND ANALYSIS _

s j

The vacuum breaker test results compared favorably with the results of analysis.

In this section, this i

D comparison is presented and analyzed.

.9 l.

6.1 Comparison of Unmodified Vacuum Breaker Test Results and I

Analysis 6.1.1 Analytical Results i

The results of the analytical investigation focused on the four moving parts of the vacuum breaker.

Applying the chugging load definition, the valvo body was found to be stressed to an insignificantly low level.

Figure i

3.4-1 illustrates the finite element model of the pallet.

Because of symmetry, only half of the model is shown.

In Figure 3.4-2, the geometry of the pallet shaft and hinge arms is shown schematically.

Also l

because of symmetry, only half the shaft and hinge arm i

assembly is used in the analysis.

For the finite element analysis, the beam element model also shown in Figure 3.4-2 was selected.

i l

The significant bending stresses in the pallet occur in l-ll the region where it contacts the front stops.

To l?

MK1-05-045 6.1 Revision 0

f h for comparison with ASME Code Y

determine a failure stress i

i al j

the stresses were averaged along pr nc p allowables, for An average stress is appropriate stress planes.

is applicable The peak stress i

failure calculations.

when fatigue is the primary consideration.

+

for an impact Figure 4.3-2 presents the stress results Since the analysis is velocity of 25.0 rads /sec.

itable the stress curves can be reduced by a su

, l, 2

linear, t velocity.

ratio to correspond to other values of impac f

lists the materials The second column of Table 4.5-1 h

critical originally used by the manufacturer to make t e Individual plants may have replaced parts components.

t rials.

with components fabricated from other. ma e Impact Velocities 6.1.2 the relation between the pallet angle In Figure 6.1-1, shown.

The

[

of inclination and the impact velocity is f:

1 series of drop first data points were obtained from the is good.

Agreement between analysis and test test data was determined by using tests.

The line fitted to the the method of least squares.

i i

6.2 MKl-05-045 s

Revision O

- l I

10 ll 6.1.3 Hinge Stresses l'

Two uniaxial strain gauges at right angles to one I

Figure another are located on the pallet hinge arm.

2A stress measured by gauges 6.1-2 compares the combined The analysi.s and 2B with the 'results of analysis.

results were determined by combining two orthogonal in the hinge arm using the SRSS method.

moments 5

was converted to Subsequently, the resulting moment l

6 stress.

1 I

From Figure 6.1-2, it can be seen that the test curve o

1 does not go through the origin of the coordinate axes.

The effect is due to the fact that the strain gauges removed were calibrated to zero stress with the pallet When the pallet was put from the vacuum breaker.

i's dead weight installed in the vacuum breaker, A corrected curve, the initial produced a small stress.

is also presented in stress having been subtracted, Figure 6.1-2.

I 6.1.4 Pallet Stresses results with analysis of test Figure 6.1-3 compares the surface of the pallet.

The the stresses on the outside calculated stresses stresses are the maximum principal 1

6.3 MKl-05-045 Revision 0

and averaged along Section A-A in Figure 4.3-2.

Distances are measured from the midpoint of the pallet along this section.

The calculated pallet stresses are taken from Reference 4.

It was necessary to ratio the stresses in Reference 4, since the angular impact velocity assumed I

analysis was 25 rad /sec while the maximun for that The ratio impact velocity from the tests was 5 rad /sec.

j is thus 5/25 or 0.2.

1 Agreement between test results and analysis is good over

,1 the interval where stress was measured.

While the test results were taken over only a portion of Section A-A, the close agreement between test and analytical results if more strain gauges were applied to the implies that the entire analytical curve could be reproduced.

pallet l

6.1.5 Shaft Bending Stresses j

lE Figure 4.3-3 shows the location of two uniaxial strain gauges located at the center of the shaft and ninety degrees apart circumferentially.

This configuration from permits calculation of the maximum bending stresses the strain gauge data.

E MKl-05-045 6.4 Revision 0

.4

(

is presented showing the test In Figure 6.1-4, a plot analysis.

results and the results of a finite element f

it can be seen that excellent i

From the figure, t results.

correlation exists between analytical and tes Conclusions from Unmodified Tesrs b

I 6.1.6 F

s and analytical results has shown a

A comparison of test the key Furthermore, remarkably good agreement.

i rity for

i assumptions of the analysis, that of l nea d

y conditions, material behavior and selection of boun ar 1

results.

ate based on the test I

appears to be very accur it can be stated with justification that Consequently, g

the test data confirms the analysis, t

1 i

l t

6.5 MKl-05-045 Revision 0-

,n i

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e 0

10 20 30 40 50 60 70 80 g

0 i

'y m.__

INITIAL POSITION (Degrees fron Vertical)

)

3.1,

~

~

1.i

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_W

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FIGURE 6.1-1 IMPACT VELOCITY VERSUS INITIAL w.

PALLET OPEN ANGLE

,<N

N 1

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s I

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s 9

k2.7- 24.5 48.0

-5 0 ~. 0 71.5 j

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s 12.5 -

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- 10, 9 '-

w

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CORRECTED s

h

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TEST DICA 3

~ s,'

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7. 5 -

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ANALYSIS POINT i

x e COMBINED TEST RESULTS N

2. 5 -

s' j,t t

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(SFS3)

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.a.

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'u-a1

s.,

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s.s ' '

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(Radians /Second)

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• IMPACT VELOCIT,Y 4

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.m

(,

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=4 I

FIGURE 6.1-2 s

s Ny g,, {

Q HINGE STEnSS VERSUS PALLET I'1 PACT VELOCITY t k l

'l

[<

t I

\\

-E t

'.d K l- 0 5 - 0 4 5 6.7 k

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-MAX PRINCIP AL STPISS OUTSIDE SURFACE t

A TEST RESULTS 30 -

i 20 -

"m i

.M 10 -

mm ta=

b M

0 2

4 6

8 10 12 DISTANCE FROM CENTERLINE (inches)

- 10 rad TEST IMPACT VELOCITY = 5.0 g

-20 I

t J

o FIGURE 6.1-3 PRINCIPAL STRESS DISTRIBUTION ALONG SECTIO A-A FROM PALLET CENTER TO IMPACT POINT MKl-05-045 6.8 Revision 0

fl ll OPEN ANGLE (Degrees) k!

ll 0

10 20 30 40 50 60 70

/

0 40 -

3

)

35 -

s P

.L.i 30 -

O 2 5 -

~

m m

o 20 -

ea e

15 -

l 10 i

E 5

TEST DATA 5

o

.i l'

O 0.77 1.62 2.47 3.32 4.17 5.02 5.78 0

(Radians /Second)

\\

IMPACT VELOCITY FIGURE 6.1-4 SHAFT SENDING STRESS VERSUS PALLET l

OPEN ANGLE AND IMPACT VELOCITY MKl-05-045 6.9 Revision 0

i 1r il l}

6.4 Calculation of the Coefficient of Restitution ll1 H

i i

f I

The finite element analysis of the GPE vacuum breaker t

was done using a coefficient of restitution of 0.6 for 1

the impact between the valve's pallet and the front i

flange.

The coefficient of restitution was found from the tests to be about 0.7.

This value represents an k

average from all the drop tests.

f I

I h

i l

r 1

I t

P MK1-05-045 6.22 Revision 0

)

7.0 VACUUM BREAKER SIZING ANALYSIS The primary containment, consisting of the drywell, wetwell, and vent system, _is designed for an external pressure of 2.0 psid.

The GPE wetwell/drywell vacuum breakers are part of the vacuum relief system designed to prevent the containment external pressure from exceeding this value.

The valves provide vacuum relief between the wetwell airspace and the drywell and. limit the water level in the vent system.

The GPE vacuum breakers are mounted on the end of the main vent lines as shown in Figure 1.1-1.

The valves allow gases in the wetwell airspace to be vented into the drywell.

A separate system of vacuum breakers provides vacuum relief between the wetwell airspace and the reactor building by permitting air to flow from the reactor building into the airspace.

The ability of the modified GPE va cuum breakers to limit the wetwell-to-drywell pressure differential was analyzed.

The analysis was performed with a computer program, described in Reference 9, which was developed during the Mark I Containment Program.

The analysis verifies that the modified GPE vacuum breakers satisfy their functional requirements with the existing number of vacuum breakers.

The modified vacuum breakers MK1-05-045 7.1 Revision 0

]

l limited the wetwell-to-drywell pressure differential to

i less than 2.0 psid and also successfully controlled the rise of the water level in the vent system.

These conclusions are based on the results from analysis of three representative GPE Mark I plants using bounding drywell depressurization transients.

7.1 GPE Valve Characteristics 1

Flow tests to determine the ef fective flow area of an 18-inch Atwood and Morrill (A&M) internal vacuum breaker were performed by FluiDyne Engineering Company.

The test results are documented in Reference 10.

This valve is similar to the GPE vacuum breakers (see Figure 7.1-1).

The effective flow areas of the GPE vacuum breakers (18 and 24-irich) were analytically determined using Reference 11.

The results of the tests with the A&M valve were used to confirm the analytically deter-mined effective flow areas of the GPE vacuum breakers.

7.1.1 Vacuum Breaker Effective Flow Area The FluiDyne tests performed with the A&M vacuum breaker established the relationship between air flow rate, pressure drop across the valve, and valve disk orienta-tion.

Differential pressu'res across the valve were 1

MKl-05-045 7.2 Revision 0

h-T.easured for mass flow rates ranging from 5 to 45 lb.,/ s ec.

The corresponding flow area was determined j

f rom measurements of the disk angle and disk angle versus valve flow area correlations.

This data along with thermodynamic stagnation conditions, allowed the valve loss coefficient and effective flow area to be calculated from the incompressible flow relation.

1 2

2 2 pg A 96*3 A g

K=

144 AP = p AP (7-1) 2 h

h i

i The ef fective flow area is then:

1 A/ 6 =

(7-2)

96. 3 / p AP loss coefficient, dimensionless wnere:

K

=

2 valve flow area, ft A

=

g gravitational constant,

=

g 2

32.2 lb -ft/lb -sec m

g 3

f p

fluid density, ib /ft

=

m AP =

differential pressure, psid d.

air mass flow rate, lb /see i

at

=

g n

.i Table 7.1-1 summarizes the FluiDyne test results includ-ing the determination of the valve ef f ective flow area 4Kl-05-045 7.3 Revision 0

from Equation (7-2).

The variance in the ef fective flow l

area when the valve is fully open (0 = 45') is reason-able for normal experimental error.

The maximum percent t

difference between the effective flow areas is eight 1

percent.

The range of the effective flow area when the valve is fully open is:

'l 2

Af/5 A&M = 1.08 - 1.17 ft 1

l

't.

The effective flow area of the A&M vacuum breaker can j

also be calculated.

Using the formulas of Reference 11, the effective flow area of the A&M vacuum breaker was calculated to be:

2 AA/R~ggg = 1.12 ft i

The agreement of the calculated and empirically deter-mined effective flow areas for the A&M vacuum breaker establishes the validity of using the formulas of

.l a

Raference 11 to calculate the ef fective flow area for f

the GPE vacuum breaker.

e The effective flow area of the unmodified 18-inch GPE vacuum breaker (Reference 12) calculated from Reference 11 is :

2 A//r apg = 1.05 ft MKl-05-045 7.4 Revision 0 I

TABLE 7.1-1 FLUIDYNE TEST RESULTS FOR 18-INCH t'

A&M VACUUM BREAKER t

Q O

A A/ /K Test No.

AP P

T o

(psi)

(psia)

( R) (lb /ft ) (lb /sec) (deg)

(ft )

(ft )

m m

1 0.16 14.44 508 0.0768 10.2 35.5 1.236 0.97 2

0.10 14.38 508 0.0765 5.15 21.5 0.757 0.62 3

0.24 14.54 504 0.0780 15.5 45.0 1.711 1.17 4

0.43 14.73 490 0.0813 20.8 45.0 1.711 1.16 5

0.58 14.88 484 0.0831 24.1 45.0 1.711 1.14 6

0.51 14.81 497 0.0805 22.5 45.0 1.711 1.15 7

0.61 14.91 494 0.0816 24.7 45.0 1.711 1.15 3

2.01 16.30 494 0.0893 44.1 45.0 1.711 1.08 10 0.21 14.43 512 0.0762 14.1 44.0 1.667 1.16 11 1.28 15.30 499 0.0828 34.8 45.0 1.711 1.11 fI*

- Differential pressure across valve AP l6 P

- Total pressure

- Temperature at valve entrance T

- Air density p

6

- Air mass flow rate f

- Angular displacement of valve disk 0

l

- Flow area corresponding to O A

'{

A/ /K - Ef fective flow area

'I 1

MEl-C5-045 7.7 Revision 0

1

' 13 7.1.*2 Modified Vacuum Breaker Assembly Effective Flow Area I

d:

I k In order to' determine the effective flow area of the entire modified GPE vacuum breaker assembly, the flow

. 3 losses due' to the modified snubber arm and the piping j

l downstream of the valve must be included.

With the 4

N exception of Browns Ferry and Pilgrim, the GPE vacuum j

t breaker installations have a straight section of pipe ji i J downstream of the valve.

Browns Ferry and Pilgrim have jj it '

60* and 90' miter elbows, respectively, downstream of I

l l the vacuum breaker.

The effective flow area of a single S

vacuum breaker assembly and the total for all assemblies for each GPE plant are given in Table 7.1-2.

EVALUATION OF CDI RESULTS Continuum Dynamics, Inc. (CDI) has developed an imprcved analytical model of the vacuum breaker / vent system fluid i

dynamics to determine vacuum breaker response during chugging.

This model takes into account the decrease in the pressure differential across the valve pallet during chugging due to pallet motion and fluid flow past the pallet.

These imprc.iments, which were not utilized in previous models, result in reduced impact velocity

'7

- j predictions.

.1 Basis of Evaluation

- t The Mark I Owner's Group authorized impact velocity calculations for each Mark I plant utilizing the improved CDI model.

The funding for this work was provided by the Mark I Owners Group.

The output of the CDI analysis is an impact velocity prediction for each GPE plant.

The NUTECH evaluation of these velocities used the vacuum breaker stress model to predict stresa levels in the critical components.

Since the stresses are directly proportional to the impact velocity, the stresses in the critical components were scaled for each plant.

MKl-05-045 8.1 Revision O 4

l F

General Electric Company has recommended in Reference 17 3o that the " expected" impact velocity predicted by CDI be multiplied by a factor of 1.18 to achieve a design impact velocity.

The expected impact velocities i

predicted by CDI for each of the GPE plants were provided in References 18 thru 27.

Table 8.1-1 lists these values along with the design value (expected f

multiplied by 1.18).

1 To determine suggested vacuum breaker modifications based on these velocity predictions, NUTECH calculated j

allowable stress values for the existing vacuum breaker materials.

Table 8.1-2 provides a summary of the allowable stresses for the critical components based on existing materials for the 18-inch vacuum breakers.

This table also includes a summary of stress levels in the various components for several impact velocities.

The information in Table 8.1-2 indicates that the allowable stresses of current components are exceeded at impact velocities above 4.5 rad /sec.

If predicted stresses exceed code allowable values, one solution is to replaca the affected component with an identical I

compenent rade of higher strength material.

NUTECH evaluated higher strength materials and determined that materials with a coda allowable stress of 70 ksi could be used for replacement parts.

Examples of such materials are shown in Table 0.1-3.

MKl-05-045 8.2 Revision O

o To determine the predicted stress in critical com-ponents, load combinations were considered.

For example, SRV and seismic loads could be postulated to occur coincident with chugging and result in additional loading on the vacuum breaker.

NUTECH's evaluation of these load combinations for one plant concluded that such additional loads contribute less than 5% of the l

code allowable stress.

l Based on stress allowables for the existing materials and the replacement materials, modification decision guidelines for each GPE plant with 18-inch vacuum breakers are given in Table 8.1-4.

Stress levels for the critical components of the Hope Creek 24-inch GPE vacuum breaker (see Figure 8.1-1) are shown in Table 8.1-5.

Higher strength replacement materials, recommended for the 24-inch vacuum breaker, are i

shown in Table 8.1-6.

a-It is recommended that the eccentric shaft be upgraded even though the calculated stress is slightly below the allowable stress.

This recommendation is based on the fact that small departurcs from pallet seating can produce large changes in the shear stress across the eccentric shafts.

A material upgrade would permit a larger margin against overstress.

l MKl-05-045 8.3

y-

.)

TABLE 8.1-1 b

[

GPE' VACUUM-BREAKER IMPACT VELOCITIES

't DESIGN EXPECTED (EXPECTED x 1.18)

?LANT (rad /sec)

(rad /sec) il Pilgrim 6.99 8.25 7.6*

Fermi 2 Browns Ferry 5.84 6.89 j

Duane Arnold 5.72 6.75 Hope Creek 5.23 6.17 Brunswick 4.72 5.57 Cooper 3.14 3.71 Hatch 1 1.07 1.26 Hatch 2 0.10 0.12 Peach Bottom 0.0 0.0 1

~

I_

3 i,

• Plant unique calculational method.

I.

p MKl-05-045 8.4 Revision 0 g

a>

l,o TABLE 8.1-2 f

g STRESS LEVELS BY COMPONENT FOR 18-INCH GPE VACUUM BREAKER f

[

STRESS (ksi) FOR VARIOUS PALLET IMPACT VELOCITIES EXISTING ASME ALLOWABLE 3.0 4.5 9.3 COMPONENT MATERIAL STRESS (ksi)

(rad /sec)

Pallet SA-516 Gr 70 35.0 21.6 32.4 67.0 a

Hinge Arm SA-516 Gr 70 35.0 11.8 17.7 36.6 o

Hinge Shaft SA-320 B8 30.0 19.1 28.6 59.2 Hinge Arm Stud SA-320 B8 30.0 12.5 18.8 38.8 1

1 1

I I

I I

MKl-05-045 8.5 Revision 0

TABLE 8.1-3 HIGHER STRENGTH REPLACEMENT MATERIALS FOR 18-INCH GPE VACUUM BREAKER t

ALLOWABLE L

'^*1PO! TENT MATERIAL STRESS aallet SA-705 Gr 630 70 ksi o

i (age hardened at 1100*F) 1 L

iinae Shaft SA-564 Gr 630 70 ksi iinge Arm (age hardened

ince Arm Stud at 1100*F) i I

I i

f l1 l1 1

I I

.I I

MKl-05-045 8.6 Revision 0 r

1 1

i

TABLE 8.1-4 r

. {

MODIFICATION DECISION GUIDELINES FOR 19-INCH GPE VACUUM BREAKER I:4 PACT 7ELOCITY (rad /sec)

ACTION Less than 4.5 No action required 4.5 to 9.3 Material upgrade 4

(

Greater than 9.3 Use a snubber

- 1

+

2 I

Assumptions:

'faterial upgrade consists of material with 70 kai code allowable

~

Loads other than chugging contribute less than 5% of allowable stress MKl-05-045 8.7 Revision 0

i 8.2 Recommendations Utilizing the guidelines in Section 8.1 and the design impact velocities in Table 8.1-1, modification recommendations for each GPE plant are shown in Table j

8.2-1.

Although no plant requires the use of a snubber, t

the snubber modification can be used in lieu of a material upgrade.

All plants should also consider replacing the original gasket with the modified For those plants needing upgraded materials, gasket.

identified in either Table 8.1-3 the critical components or Table 8.1-6 should be upgraded.

ii e

C

I

'l i

MK1-05-045 8.11 o

Revision 0

ih TABLE 8.2-1 i'

t Modification Recommendations i

i i

e-Current Materials Acceptable:

d Cooper 3.71 rad /sec Hatch 1 1.26 rad /sec 1

Hatch 2 0.12 rad /sec Peach Bottom 2 & 3 0.0 rad /sec i

Upgrade Materials of Critical Components:

j I'

.i Pilgrim 8.25 rad /sec Fermi 2 7.6 rad /sec Browns Ferry 1, 2& 3 6.89-rad /sec i

Duane Arnold 6.75 rad /sec f

Hope Creek 6.17 rad /sec Brunswick 1 & 2 5.57 rad /sec t

'.11 plants should consider replacing the original gasket with

ne modified gasket.

'4Ki-05-045 8.12 Revision 0

Phase II of modificatio the GPE w tw e

pr totype n has be ell-to-dryw ll

\\

o en e

\\

succ v

br snubber s has bee modific tion tssfully e

u eaker a

uded.

re n de igned, o the GPE v sults s

of the that e generic

analyzed, cug s

a the c

and propo impact modificationa tivit teste pallet sd e

e demo v lo itic substantially v lv.

e a

nt s

c e

Simila ly mpared a co r

s eal properly r dg e

the to o

an m dified anm difie4 Analytic l install e gasket o

a ha cuum br studies hav asily, a d r s be va en n

sht eaker also esist e

ting dryw llsa tisfie show foldov limi n that er.

s the the e

during dryw and original modified vet design n

ell depr system diffe m dification d o

cri teri essuriz tic ential r

a actical esign ha a tra pre pr s been nsients.

ssutr modificatio show means n fo n to be

Thus, of th@

mitigating the e in the Mark viable, r us a

GPE vacuum bre ker.

effects I

a pla ts s

of n

chugging loads as e

A finite br element on the eaker a

was de nalysis mo of te t an data.

nstr ted s

u to be nr dified a

o NUTECH ha ac GPE v u

nmodified va cur te by c acuum s

a also c

ev lu ted ompa iso u ing the Co ti eaker impa t uum br a

s a

r the n to n

r dyn esults nuu c

s amic model.

m Dyna ics, v locitie e

of m

s pr dicted Bas d In.

c e

MKl-05-045 n these improv d e

o e

Revisio v lo itie fluid e

c n0 s,

NUTECH 91 has

h

2 commended modifications for each Mark I GPE plant as irllows

urrent materials of critical components are acceptable f

Cocper Hatch 1, 2

Peach Bottom 2 & 3 1

Teolace critical components with materials of hicher strencth I

Pilgrim Fermi 2 Browns Ferry 1, 2,

& 3 Duane Arnold Brunswick 1 & 2 i

Hope Creek l

Those plants needing to upgrade materials could use the snubber modification in lieu of stronger materials.

All i

plants should consider replacing the original gasket with the modified gasket.

1 The work completed in Phase II of the GPE vacuum breaker i

1 modification program has demonstrate' the generic l

1 MKl-05-045 9.2 Revision 0 1

a

F

.pplicability and viability of the snubber modification y

acncept.

If plants select to use the snubber modifica-

-ion, additional plant unique analyses should be J

cmpleted to confirm the generic analyses presented in h

this report.

Plant unique calculations should be performed to confirm the results of the generic vacuum breaker sizing analyses described in Section 7.

These unique analyses could also reduce some of the plant i

.]

conservatisms identified in Section 7.

Similarly, 4

analyses confirming that the modified vacuum breaker

]

reduces impact velocities during chugging to acceptable levels should be performed, utilizing appropriate forcing functions.

1 Included in Appendix G of this report is a generic Safety Evaluation of the modification to the GPE aetaell-to-drywell vacuum breakers.

The information in Appendix G is intended to serve as a guide for use in preparing a plant unique Safety Evaluation Report (SER) if the modification is installed.

The plant unique SER should document the confirming plant unique analyses iescribed above.

1

]

1 1

'Kl-05-045 9.3 Revision 0

1

h

!b.

t

10.0 REFERENCES

[

1.

" Mark I Containment Program Full-Scale Test Program Final Report," General Electric Co. Report, NEDE-E 24539, April 1979.

y 2.

" Status Report - GPE Wetwell-to-Drywell Vacuum

,L Breaker Modification," NUTECH Report, MKl-05-002, d

July 1981.

[

s 3.

DISCO 1.4.0 Verification / Calibration Analysis for

}J Mark I Owners Group, NUTECH Calculations, August 1982.

NUTECH File Number 138.2105.0709.

4.

" Dynamic' Analysis of Wetwell-to-Drywell Vacuum

h Breakers for Mark I Program Short Term Loads c.,

(Operating Plants)," NUTECH Report, GEN-67-015',

Revision 0, May 1980.

'T 5.

" Dynamic Analysis of Wetwell-to-Drywell Vacuum Breakers for Mark I Program Short Term Loads (Plants Under Construction)," NUTECH Report, GEN-67-018, Revision 0, Jdly 1980.

}

G 6.

" Test Plan and Procedures for Dynamic Testing of U.

the 18" Unmodified GPE Vacuum Breaker," NUTECH h

Engineers, Test Plan MKl-05-023, Revision 0, March h

1982.

yy 7.

" Test Plan and Procedures for Dynamic Testing of

[

the 18" Modified GPE Vacuum Breaker," NUTECH I

Engineers, Test Plan GEN-79-001, Revision 1, August 1982.

L b

8.

" Test Report for Dynamic Testing of the 18" Modified GPE Vacumn Breaker," NUTECH Testing 5

Services, P.eport GEN-79-004, Revision 0, September f{

1982.

cf (L

9.

Wolfe, W.

L.,

" Mark I Containment Program, Mark I I*

Wetwell-to-Drywell Vacuum Breaker Functional h;

Requirements, Task 9.4.3,"

General Electric Co.,

Report No. NEDE-24802, April 1980.

i!

5e 10.

"18-Inch Check Valve Tests," FluiDyne Engineering Corp. Job No. 0988, November 1973.

t, 11.

Idel'Chik, I.E.,

Handbook of Hydraulic Resistance, Coefficients of Local Resistance and of Friction, Israel Program for Scientific Translation Ltd.,

ij 1966.

8'!

t i-i!

MKl-05-045 10.1 el Revision 0 1-

1 o

12.

" Vacuum Breaker, 18" 150 Flange Out]et x 20" Seat Inlet," GPE Controls Drawing No. LD-240-210, Revision B, July 1973.

13.

'24" Slimline Vacuum Breaker," GPE Controls Drawinc No. LD-240-447, Revision A, July 1979.

a j

14.

" Hope Creek 1 Containment Data," General Electric Nuclear Energy Division, Specification No. 22A6209, Revision 0, April 1979.

k 15.

" Calculation of GPE Wetwell/Drywell Vacuum Breaker Effective Flow Area," NUTECH Calculations, Revision 0,

July 1982, NUTECH File No. 138.2105.0021.

16.

" Pressure Suppression Test Program," Appendix I,

g Preliminary Hazard Summary Report, Bodeca Bay 3

Atomic Park, Unit 1,

General Electric Co. and Pacific Gas and Electric Co.,

December 1962.

17.

General Electric Company, " Mark I SSE Question Response d315," Transmitted via GE letter MI-G-43 to all Mark I utilities, July 1982.

18.

" Revised Vacuum Breaker Valve Response for Fermi-2,"

Continuum Dynamics, Inc., Tech. Note No. 82-26, Revision 0, September 1982.

}

19.

" Improved Dynamic Vacuum Breaker Valve Response for Duane Arnold," Continuum Dynamics, Inc., Tech. Biote No. 82-6, Revision 1, September 1982.

20.

"Imprcved Dynamic Vacuum Breaker Valve Response for Cooper.," Continuum Dynamics, Inc., Tech. Note No.

82-8, Revision 1, September 1982.

21.

" Improved Dynamic Vacuum Breaker Valve Response for Peach Bottom," Continuum Dynamics, Inc., Tech. Note No. 82-10, Revision 1, September 1982.

22.

" Improved Dynamic Vacuum Breaker Valve Response for Browns Ferry," Continuum Dynamics, Inc., Tech. '!ot e No. 82-11, Revision 1, September 1982.

i 23.

" Improved Dynamic Vacuum Breaker valve Response for Hatch 1 Plant," Continuum Dynamics, Inc., Tech.

Note No. 82-13, Revision 1, September 1982.

24.

" Improved Dynamic Vacuum Breaker Valve Response for 3

Hatch 2 Plant," Continuum Dynamics, Inc., Tech.

J Note 'To.

82-14, Revision 1, September 1982.

MKl-05-045 10.2 Revision 0

i l

h 95.

" Improved Dynamic Vacuum Breaker Valve Response for a,a Pilgrim," Continuun Dynamics, Inc., Tech. Note No.

82-19, Revision i, September 1982.

26.

" Improved Dynamic Vacuum Breaker Valve Response for the Brunswick Plant," Continuum Dynamics, Inc.,

Tech. Note No. 82-22, Revision 1, September 1982.

27.

" Improved Dynamic Vacuum Breaker Valve Response for Hope Creek," Continuum Dynamics, Inc., Tech. Note No. 82-30, Revision 1, September 1982.

1 1

3 1

1 1

1 1

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Revisi,on 0 B.12

t i

i

'2 Pallet Gasket Modification f

4 L

A ring stiffened sealing gasket has been suggested as a replacement for the gasket supplied by the manufac-turer.

This' stiffened gasket precludes foldover during i

i chugging.

l i-l l

'4Kl-0 5 -0 4 5 G.5 i

Revision 0 it ja t --

~J.

~-

-*.s G.2.1 Plant Application The modified gasket is designed to replace the flexible gasket supplied by the manufacturer.

It is applicable to GPE wetwell-to-drywell vacuum breakers installed in General Electric Boling Water Reactors having Mark I containments.

G.2.2 System f

The gasket modification applies to 18" and 24" GPE i

wetwell-to-drywell vacuum breakers.

These valves are part of the Mark I vacuum relief system.

G.2.3 Description of Modification The modification consists of sandwiching a flat eighteen gauge stainless steel ring between two layers of ethylene prophylene material.

A compression molding process is used to bond the three layers of material.

l l

l As designed, the modified gasket can be installed on the i

j vacuum breaker pallet without removing the valve from i

the main vent header.

Since the modified gasket has the same thickness as the one it replaces, there should be j

i no need for adjusting the pallet.

l MK1-05-045 G.6 Ravision 0 I

m

2 G.2.4 Purpose of the Idodification The purpose of the modified gasket is to prevent foldover during chugging.

G.2.5 Safety Evaluation Functional requirements for the Mark I containment as stated in the FSAR for each individual plant have not been compromised.

i i

i

?

5 4

J t

MKl-05-045 G.7 Revision 0

.