ML20062J979
| ML20062J979 | |
| Person / Time | |
|---|---|
| Site: | Midland |
| Issue date: | 08/06/1982 |
| From: | Jackie Cook CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | Harold Denton, James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III), Office of Nuclear Reactor Regulation |
| References | |
| 10CFR-050.55E, 10CFR-50.55E, 17560, NUDOCS 8208160514 | |
| Download: ML20062J979 (37) | |
Text
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Iof Consumers Power n
.c Vice President - Projects, Engineering and Construction Generet offices: 1945 West ParneH Road, Jockeon, MI 49201 e (517) 788r0453 August 6, 1982 82-06 #2 Mr J G Keppler, Regional Administrator US Nuclear Regulatory Commission Region III 799 Roosevelt Road i
Glen Ellyn, IL 60137 Mr H R Denton (20)
' Office of Nuclear Reactor Regulation US Nuclear Regulatory Commission Washington, DC 20555 MIDLAND PROJECT -
DOCKET NOS 50-329 AND 50-330
-B&W STEAM GENERATOR AUXILIARY FEEDWATER HEADER DESIGN CHANGE i
FILE:
0.4.9.62, 0505.2 SERIAL:
17560
Reference:
(1)' J W Cook letter to J G Keppler Serial:
17504,' dated May 26, 1982 This letter provides another interim 50.55(e) report concerning the B&W steam generator auxiliary feedwater header. Consumers Power Company and B&W con-sultants have completed an internal design review on the design modifications necessary for the Midland steam generator, and we are confident the planned
' modifications will provide a permanent solution to the problems reported
.previously with the internal auxiliary feedwater header. is a description of the modification details and design criteria for the Midland steam generator. The design provides for the addition of an external auxiliary feedwater distribution header with eight (8) injection nozzles through'the steam generator shell. The ASME III design reports on the steam generators will be revised, and design reports on the external piping will be submitted for ASME authorized inspector review. The design also O'o:
provides for abandonment and stabilization of the existing internal feedwater o$$
header which has not been damaged at Midland from operations. Enclosure 1
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also discusses the Midland plans for preoperational testing and post-operation g
inspections.
Sketches are also provided of the revised auxiliary feedwater P P ng inside the steam generator compartment. A schedule of the necessary i i o
' $g activities required to implement this modification is provided for your g
information.
<D O f is a drawing package of the new external auxiliary feedwater
.[
gg header to be used at Midland. A general assembly drawing and a detailed o
ma.u) drawing of the new injection nozzle is shown.
TMG 1 1 1982 OC0882-0004A-MP01' W
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i Serial 17560 2
82-06 #2 We have had several conversations with the staff during which they requested certain details. We are confident that the information enclosed provides the necessary Midland specific details pertaining to auxiliary feedwater header repairs. We are hopeful NRR approval to begin repairs can be granted as soon as possible.
Another report, either interim or final, will be sent on or before October 30, 1982.
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W JWC/DTP/WJC/ c
Enclosures:
(1)
Evaluation of Internal Auxiliary Feedwater Header and Installation of External Header at Midland Units 1 and 2 (2) B&W Drawing No 1134961F, Rev 6/18/82 B&W Drawing No 1132211D, Rev 7 CC:
Document Control Desk. NRC Washington, DC, w/a RJCook, NRC Resident Inspector Midland Nuclear Plant, w/a CBechhoefer, ASLB Panel, w/o RSDecker, ASLB Ponel, w/o FPCowan, ASLB Panel, w/o JHarbour, ASLB Panel, w/o AS&L Appeal Panel, w/c MMCherry, Esq, w/o MSinclair, w/o BStamiris, w/o CRStephens, USNRC, w/o WDPaton, Esq, USNRC, w/o FJKelley, Esq, Attorney General, w/o SHFreeman, Esq, Asst Attorney General, w/o WHMarshall, w/o GJMerritt, Esq, TNK&J, w/o JRajan, USNRC, w/a RHernan, USNRC (2), w/a DJudd, B&W, w/o OC0882-0004A-MP01
r Sarial 17560 3
82-06 #2 BCC: JLBacon, M-1085A, w/o RCBauman, P14-312B,w/a WRBird, P14-418A, w/a NRC Corres File, P24-517, w/a LHCurtie, Bechtel Ann Arbor, w/o LEDavis, Bechtel-Midland, w/o MADietrich..Bechtcl-Midland, w/o GREagle, CPCo Ann Arbor, w/o BWMarguglio, Midland, w/o DBMiller, Midland (3), w/a JAMooney, P14-ll5A, w/o JARutgers, Bechtel Ann Arbor, w/o REWhitaker, Midland, w/a MLCurland, Midland,w/o DMTurnbull, Midland, w/a MEGibbs, IL&B, w/o FDField, Union Electric, w/o RAWells, P14-ll3A, w/o FCWilliams, IL&B Washington, w/o PSteptoe, IL&B-Chicago. w/o RHustin, Washington, w/a DTPerry, P-14-300, w/o WJCloutier, P-24-505,'w/o DMBudzik, P-24-517A, w/o FJLevandowski, B&W-Lynchburg, w/a EMHughes, Eechtel Ann Arbor, w/o AVovides, Bechtel Ann Arbor, w/a l
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OC0882-0004A-MP01 L-
o EVALUATION OF INTERNAL AUXILIARY FEE 0 WATER HEADER AND INSTALLATION OF EXTERNAL HEADER AT MIDLAND UNITS 1 AND 2 mi0782-2296a173
1.0 Introduction There are two configurations of auxiliary feedwater (AFW) header assemblies which are used on the steam generators for Babcock &
Wilcox's 177 Fuel Assembly Plants. The first type uses an external distribution header mounted outside the once through steam generator (OTSG) with nozzles penetrating the shell and shroud. The second type uses an internal distribution header mounted inside the OTSG. Recent inspections showed damage in the internal AFW headers at three plants:
Duke Power Co., Oconee 3; Sacramento Municipal Utility District, Rancho Seco; and Toledo Edison Co., Davis-Besse 1.
The internal AFW header design also exists at General Public Utilities, Three Mile Island (TMI-2). The Midland units also have the internal header design.
TMI-2 has not been inspected. The Midland Units have not operated and the internal header has not experienced to the damage that exists at the operating plants. The external AFW headers have operated for more than 22 reactor years with no evidence of damage. They are used at:
Duke Power Co., Oconee 1 & 2; Arkansas Power & Light Co., ANO-1; Florida Power Corp. Crystal River 3; and General Public Utilities, Three Mile Island-1.
The purpose of this report is to describe the evaluation and replacement activities related to precluding the internal header damage at Midland Units 1 and 2.
t In the following section of this report, facts will be presented to show that a most probable cause of the internal header damage has been established and that the intended installation and use of an external header will prevent occurrence of damage to both the non-functional mio782-2296a173 1-1
internal header and the new external header.
In addition, the report will show that the external header provides all the functional requirements previously provided by the internal header design.
1.1 Internal AFW Header Design The internal AFW header is a rectangularly shaped torus fabricated of welded plate segments. The header is positioned on the upper end of the upper vertical cylindrical baffle (upper shroud) (see Fig. 1-1).
The header also serves as a continuation of the upper shroud to separate the tube bundle from the steam annulus. The header is positioned and retained by eight sets of inner and outer brackets welded ~to the bottom of the header and match drilled through the shroud. A dowel passes through each set of brackets and is welded to the inner bracket (see Fig. 1-2).
A single 3 1/2 inch diameter AFW nozzle delivers water to the header via a thermal sleeve which is a slip fit into the header (see Fig.
1-3).
Water leaves the header through 60 - 1 1/2 inch diameter flow holes near the top of the inner header wall. The flow holes are equally spaced around the circumference. There are 8 - 1/4 inch diameter drain holes near the bottom of the inner vertical wall.
The auxiliary feedwater system piping connects to the AFW nozzle on each steam generator. During power operation the internal AFW header, thermal sleeve, and a portion of the horizontal piping would be filled with dry superheated steam.
The bracket and dowel arrangement permits differential thermal movement of the internal AFW header in a radial direction during operation.
mi0782-2296a173 1-2
1.2 Internal AFW Header Functional Requirements The internal auxiliary feedwater header provides three functions. The header distributes auxiliary feedwater whenever required over the steam generator tube bundle at a point just below the upper tubesheet.
It also acts as an extension of the upper shroud which separates the tube bundle from the steam outlet annulus.
The third function is served while the plant is shutdown. When a plant is in wet lay up the header distributes water and chemicals, during fill and recirculation, to the top of the steam generator secondary side to insure a well mixed solution.
1.3 History of the Problem In April, 1981 tube leakage was experienced at the Davis-Bessee 1
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station. An eddy current (EC) inspection determined that two adjacent peripheral tubes were leaking. The elevation and circumferential location of the tube leaks were aligned with the location of a header bracket pin. An expanded eddy current inspection carried out in this generator identified one additional tube indication (ding) which could be correlated to a dowel pin location.
In May, 1981 tube leakage at Rancho Seco was identified. An inspection was performed at all dowel pin locations. The inspection recorded dings in tubes at five of the eight dowel pin locations.
In February,1982 a leaking tube at the bundle periphery was identified at Oconee 3.
An eddy current inspection performed at four of the eight dowel pin locations recorded no tube indications.
mi0782-2296a173 1-3
As a result of these indications a visual inspect. ion of the Davis-Besse
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f 1 internal header was planned for their 1982 refueling outage. The intent of these inspections was to check for loose dowel pins in the brackets attaching the internal header to the steam generator suroud.
It was during this inspection that the header and bracket damage was first detected. The results of this inspection ler) to the irispections at Rancho Seco and at Oconee 3 where similar damage was,found.
Following the preliminary inspections during March of this ye'ar at Davis-Besse and Rancho-Seco, a meeting was held April 24, l'382 to provide the NRC staff with information then available on this problem.
Since that time, there have been several plant specific meetings with the staff to review additional inspection information and the repair plan. The three operating plants with the internal h'eader design have
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also filed Licensee Event Reports with their regional tiRC Inspection and enforcement Offices and Consumers Power Company his filed a 10CFR50.55e Report with their NRC I & E regional office.
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2.0 Site Inspections and Results As a result of the 1981 eddy current inspection additional inspections were initiated at Davis-Besse 1 in March of this year during their planned refueling outage. The damage noted during that inspection and the absence of any plant specific cause suggested the need for inspection of Rancho Seco and Oconee 3 internal headers.
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Thesiteinspedtiontechniqucls used for these inspections include direct visual inspection, dimensional measurement, fiber optics and remote TV camera viewing.
In addition eddy current testing (ECT) in being used to determine tube wall thinning. Analysis of tbe ECT ~Jata is used to indicate. clearances' between peripheral tubes and the inner most parts of the internal headers. Visual examinations along with ultrasonic, (UT) and penetrant tests (PT) are also being performed to establish the mechanical integrity of the feedwater header plates and welds and the steam generator shell in the vicinity of the new AFW
_ nozzle penetrations.
With'one exception, the inspection results from all three plants were
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i generally similar.
Portions of the outer vertical wall of the header were distorted inward toward the center of the generator, some#of the i
support -br' ckets were bent or damaged and some of the dowel pins were a
either out of-position or missing (see Fig 2-1).
The exception was the presence of holes in the' top and bottom plates of the headers at Oconee 3.
Because this damage is concluded to have occured during operation of these plants and because.the Midland Units have not s
operated, there is no reason to expect that the Midland internal headers have bee'n dama ed in a similar minner.
nio782-2296a173 2-1 b
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3.0 Probable Cause 3.1 Mechanisms Examined A number of mechanisms were evaluated as probable causes of the internal header damage. Both stress and thermal hydraulic calculations were performed to analyze these mechanisms. Mechanisms examined were:
Impingement velocity and turbulent flow conditions due to high o
AFW flows High pressure drop due to condensation at the beginning of AFW o
flow when the cold water enters the steam-filled header Thermal stresses due to cold AFW flow into a header preheated by o
steam to about 550-590*F 3.2 Probable Cause Condensation-induced high pressure difference has been found to be the damage mechanism which could create large enough pressure differentials to partially collapse the internal AFW header. The tall vertical walls have low rigidity and tend to buckle inward at about 200 psi pressure differential. This inward diatortion could bow the lower plate upward binding the bracket and dowel pins. This could prevent the dowel pins from sliding and ratcheting of the brackets and pins could occur.
Also, because portions of the header may be cooled more than others during AFW injection, the header may become distorted, eg, out-of-round or twisted, and this too could bind the dowel pins and prevent slipping. Forces may be sufficient to break bracket ligaments, bend pins, break bracket or dowel pin welds and deform inner brackets, mi0782-2296a173 3-1
Repeated application of such forces could increase the severity of the damage.
According to the Creare Report, NUREG 0291(I) condensation-induced high pressure difference can be anticipated under the following conditions:
1.
Trapped steam 2.
Sufficient flow of subcooled water 3.
Sufficient subcooling Resulting in:
- Rapid condensation of steam
- Sudden depressurization of steam void NUREG 0291 describes condensation-induced pressure surge phenomena which can occur in a flowing system. These phenomena can be separated into three distinct stages. Stage #1 ts the process of void formation, assumed to occur maini.y by fluid mechanical interaction, possibly aided by countercurrent steam flow. Stage #2 is the condensation and heat l
transfer driven void collspse, resulting in potentially very large localized pressure decreases in the header. Stage 03 is the water slug impact with the upstream water, creating the large amplitude shock waves.
The AFW header internal damage mainly shows evidence of an inward collapse of the outer (shellside) wall. The " ballooning" effects which l
l are typical of feedwater line water hammer were not evident.
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The inward bowing of the shellside header wall is postulated to be attributed to high velocity steam flowing through the holes on the inside (tubeside) of the header, which, by a method similar to the "open channel" wave effect described by Creare, could create a water slug and a trapped steam void tangent to the outer wall inside the header. During the subsequent rapid void collapse, a large pressure differential could be created across the outer wall, with normal OTSG pressure (1000 psi) on the outside and very low pressure in the void region. The outer AFW header wall should bow inward under this pressure difference, and permanent deformation could result if the pressure difference is large enough.
It should be noted that the AFW internal header is not similar to auxiliary feedwater pressure piping in this respect. Auxiliary feedwater piping outside the steam generator is designed for system pressures and would not yield under the differential pressures resulting from void condensation.
There are two reasonable explanations why the headers did not suffer more severe damage from the positive shock wave. First is that the sixty holes in the inner header wall attentuate the pressure pulses.
The second explanation is that the deformation of the header wall reduces the potential energy of the slug-void interaction. That is, the wall deformation compresses the void region and reduces the pressure difference driving force which accelerates the slug.
If this happens, the shock wave would be attenuated.
In summary, the observed damage to the AFW headers points to a conclusion that the probable damage mechanism is condensa*..on-induced high pressure difference. The first phase of the pressure transient mio782-2296a173 3-3
creates a condensation induced high pressure difference across the AFW P
header wall when trapped steam pockets collapse, resulting in header
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E deformation. The effects of the resulting shock wave were not evident t
.due to the attenuation by both the wall deformation and by the flow holes in the header which provided a fluid " escape route".
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4.0 Description of Repair Any modification to the Midland Units required that the modification meet all the auxiliary feedwater functional requirements.
The most logical choice from a functional standpoint was to use either a configuration as similar as possible to that used on other operating OTSGs, i.e., the external AFW header o, since the Midland internal header was not damaged, to modify the header to prevent any future damage.
It was determined, based on technical feasibility and schedule, that the best solution would be to add an external header and abandon the use of the internal header for AFW introduction into the steam generator.
It was considered desirable to retain the internal header as an extension of the shroud to serve as a steam flow baffle but to weld the header to the shroud to prevent future movement. The nozzle holes in the steam generator shell were located so that they could serve as welding access openings.
4.1 Internal Header 4.1.1 Design Requirements (2)
A set of design requirements for securing the internal header has been established. The requirements, met by the repair described in Section 4.2, include the following:
- The header must be maintained in a fixed position relative to the tube bundle. The minimum clearance between unplugged (functional) steam generator tubes and the header / restraint is 1/8" when the plant is shutdown. This clearance was based cn the sum of the mi0782-2296a173 4-1
maximum differrential thermal motion and the maximum movement due to flow induced tube vibration times a factor of two.
Since the Midland headers are not distorted, this requirement will be met with considerable margin.
The secured header must serve as an extension of the upper cylindrical baffle to channel steam flow through a similar flow area as it did in the original design.
- The secured header must withstand the expected static and dynamic loads resulting from:
- 1) normal and upset operating transients
- 2) seismic conditions (OBE) 3)
flow-induced vibration
- The header must not cause leakage of steam generator tubes when subjected to faulted conditions of:
- 1) steam line break 2) loss of coolant accident 3) feedwater line break
- 4) seismic conditionz (SSE) mi0782-2296a173 4-2
The design, fabrication, and examination of the devices to secure the internal header must meet the intent of the ASME Boiler and Pressure Vessel Code,Section III, Subsection NB for Class 1 Components, 1977 Edition including Addenda through Summer 1978, except that:
1.
Certification per NB-4120 and-NB-8100 is not required.
2.
No weld joint category applies (Reference NB-3551).
3.
The required examination of welds consists of visual examination of the root pass and final. trface per Appendix KVI-3700 with the acceptance standards of NG-5360.
The design must minimize the risk of creating loose parts in the i
steam generator. The existing dowel pins will be welded on the outside of the shroud in addition to the weld that already exists on the inside of the shroud.
The design must be compatible with the carbon steel materials of the header, upper cylindrical baffle, and steam generator shell, and it must be compatible with the feedwater chemistry requirements.
- The process of securing the header must be accomplished via the existing secondary manway and/or the auxiliary feedwater nozzle openings, old and new.
- The process of securing the header must not damage the tubes, create loose parts inside the steam generator, or introduce mi0782-2296a173 4-3
unacceptable contaminants which cannot be removed from the steam generator.
- The design must meet all current design bases.
4.1.2 Internal Header Repair The bottom of the internal header will be secured to the shroud in eight locations around the circumference. These will be oriented above and adjacent to the circumferential location of the shell to shroud alignment pins. At each location a 7 inch long continuous 3/4 inch fillet weld will be used at attach the outside of the snroud to the bottom of the header.
In the same locations 1/2 inch thick by 5 inch long by 3 inch wide gusset plates will be fillet welded to the bottom of the header and the outer face of the shroud. The fillet welds' and 5" gusset' plates are designed to take the forces and moments generated by normal operating or accident conditions.
Figure 4-1 illustrates the intended modification.
l The thermal sleeve used to direct AFW to the internal header will be removed. A flange will be welded to the existing nozzle and a blind l
flange will be used to seal the opening.
As mentioned at the beginning of this section a major consideration l
in the repair approach was to provide access to the internal header for welding with'a minimum of machining on the shell. An engineering evaluation indicated that 4 15/16" diameter holes would provide j
sufficent access for. securing the header without unacceptable effects l
l on the pressure boundary integrity or mechanical strength of the steam generator shell. A demonstration of the ability to secure an j
mi0782-2296a173 4-4 i
internal header to the shroud by the described method was performed on a full scale steam generator mock-up on May 21, 1982.
It is important to note that the probable cause of damage to the internal header, identified in Section 3.2, describes a condition that only exists when that header is used for auxiliary feedwater additions.
It is, therefore, considered reasonable to leave the internal header in place, once it is properly secured, since it will no longer be exposed to conditions which produced the damage.
4.2 External Header 4.2.1 Description The new external' header will be connected to the existing plant auxiliary feedwater line by 6" diameter piping. The header will be about a 300* circumferential ring made from 6 inch schedule 80 pipe capped at each end. Eight 3 inch schedule 80 pipe risers equally spaced around the ring feed auxiliary feedwater through the steam generator shell and shroud to the secondary side of the tubes.
Flanges will be located in the vertical risers just above the ring and at each point of entry into the steam generator shell. A tapered thermal sleeve will direct the flow from the shell opening through j
the shroud to the steam generator secondary side.
l The centerline of the riser inlet to the steam generator will be located about 14 inches above the top (15th) tube support plate. The injection point for AFW in the Midland replacement design is about three inches higher in elevation than in existing external header designs to allow access for securing the internal header. This mi0782-2296a173 4-5
difference in injection point elevation could result in a small increase in flow induced vibration loads on the tubes since the injection point at Midland with the external header is about 3 inches closer to the tube midspan that in the existing internal header plants. However, this increase in vibration loads is more than offset by a reduction in these flow loads due to a more gradual taper in the thermal sleeve resulting in a lower discharge velocity. The risers will contain variable size orifices at the flange in the vertical run to ensure sufficiently equal distribution of flow.
Figure 4-2 shows the arrangement of the replacement external AFW header.
4.2.2 Functional Design Requirements Specifications have been issued to insure the header design meets its two basic functional requirements, i.e.,
supplying and distributing auxiliary feedwater to the steam generator tube bundle and providing distribution of recirculating water and chemicals during wet lay-up.(3)
A maximum flow of 300 gpm per riser has been established by B&W to limit the flow induced vibration loading.( ) (6)
This flow limit was met by selecting an appropriate number and configuration of the nozzles.
Design, fabrication and analysis of the B&W supplied components will t
meet the requirements of Section III of the ASME code, Class 2 for the header ring, risers and shell flanges.( )
mi0782-2296a173 4-6
4.2.3 Comparison to Existing Designs As pointed out in Section 1.0 of this document, the retrofit of the auxiliary feedwater external header has the advantage of applying a design proven in more than 22 reactor years of operation at five operating plants. No evidence of water hammer or other steam condensation-induced damage has been noted in the existing external header designs. The thermal sleeves have been inspected at all operating plants that use the external header design and have found to be free of damage due to thermal shock or condensate induced pressure surge. The thermal sleeves provided for Midland have been designed to prevent the occurrence of minor cracking which has been experienced at some plants.
There are two additional features in the external header design which tend to minimize the possibility of any damage by condensation induced pressure surges. These are:
- 1) Top discharge nozzles, which preclude header ring draining ands suppress slug formation, and
- 2) Snort horizontal runs, which limit void formation and slug acceleration.
mi0782-2296a173 4-7
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I 5.0- Pre-Operational Tests t
This modification is presently intended to be made before the intial steam generator hydro-test. The testing of the modified system will be I
completed during the normal pre-operational test period.
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6.0 Post Operation Inspections The plant ISI/IST Programs will be revised to require EC inspection of
. tubes at. selected perimeter locations adjacent to the aux'feedwater injection points during the first and second refuelings.
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7.0 Safety Assessment and Summary B&W and Consumers Power recognize that this repair has safety significance. The retrofitted external header is -a component of a safety system whose function is designed to mitigate the following events:( )
- 2) Loss of offsite AC Power
- 3) Main Steam Line Break (SLB) 2
- 4) Small Break Loss of Coolant Accident (LOCA) - less than 0.5 ft break Furthermore, the modification has considered the need to secure the internal header to assure no damage to steam generator tubes.
Analysis and design evaluations have been performed to assure that the AFW functions of the external header will be provided. Backing this assurance is the satisfactory experience at the five operating plants presently using the external header design.
Both the retrofitted external header and the securing of the internal header have had independent evaluations at B&W by in-house Design Review and Consumers has retained MPR Associates to provide a review of the modification.
In summary, Consumers and MPR working closely with B&W consider that a logical probable cause for the original damage has been established and mi0782-2296a173 7-1
t that the repair program fully considers that cause and will preclude the occurrance of damage at. Midland.
In addition the replacement external header is a proven design approach that has been successfully
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operated. Furthermore, the Midland units will be inspected the end of the first fuel cycle and periodically thereafter to assure no significant degradation of the units ' occurs in service, as discussed in 1
Section 6.
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8.0 Auxiliary Feedwater Line Modification The routing of the auxiliary feedwater line will not require a major revision because of this modification. Attached is Figure 8-1 through 8-4 which depict the revised layout. As shown on these figures, the only change to the layout is within the steam generator compartment.
The objective in rerouting this pipe was to make the pipe constantly rising with the steam generator inlet being the highest point. This routing helps provide protection against potential line drainage and water hammer. Consumer's A/E is currently performing a stress analysis on the revised routing to define any addition or changes to pipe hangars, supports, or restraints which may be required to meet the existing stress limits for the Midland AFW piping.
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b 9.0 Schedule Figure 9-1 depicts the schedule and sequence of activities which are required to complete the installation of the auxiliary feedwater header. The modification has been scheduled to be complete with the exception of seismic hangars or helba whip restraints by the steam generator secondary hydro test. Those items not completed by the hydro test will be completed before hot functional testing.
mi0782-2296a173 9-1
10.0 References 1.
NUREG-0291, NRC-1, An Evaluation of PWR Steam Generator Waterhammer, Final Technical Report, June 1, 1976 - December 31, 1976, by Creare, Inc., Hanover, NH.
2.
Engineering Requirement for Internal Header Stabilization B&W Doc No 51-1134169-06.
3.
Functional Specification for Steam Generator Emergency Feedwater -
Header B&W Doc No 18-1134783'-00.
4.
Equipment Specification for Steam Generator Auxiliary Feedwater Header B&W Do No 08-1134172-01.
5.
Response of Tubes to Random Turbulence Excitation - AFW B&W Doc No 32-1134728-00.
6.
Revised AFW Header Capacity B&W Doc No 32-1134729-00.
7.
Internal AFW Header Tiedown Analysis B&W Doc No 32-1134668-00.
mi0782-2296a173 10-1
t Figure ONCE-THROUGH STEANI GENERATOR WITH INTERNAL AUX. FEEDWATER HEADER f_ Primary inlet nozzle y
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