ML17308A472
| ML17308A472 | |
| Person / Time | |
|---|---|
| Site: | Saint Lucie  |
| Issue date: | 05/03/1989 |
| From: | FLORIDA POWER & LIGHT CO. |
| To: | |
| Shared Package | |
| ML17222A789 | List:
|
| References | |
| NUDOCS 8905150094 | |
| Download: ML17308A472 (34) | |
Text
ATTACHMENT 1 Marked-up Technical Specification
- Pages, St. Lucie Unit 1:
3/4 4-5 3/4 4-8 (with insert)
B 3/4 4-3 8905i50094 390505 PDR ADOCK 05000335 P
REACTOR COOLAh.'YSTEM STEAM GElIERATORS LIMITING CONOITION FOR OPERATION 3.4.5 Each steam generator shall be OPERABLE.
APPLICABILITY:
MOOES 1, 2, 3 and 4.
ACTION:
with one or more steam generators inoperable, restore the inoperable generator(s) to OPERABLE status prior to increasing T above 2OO'F.
avg SURVEILLANCE REOUIREIME.'ITS 4.4.5.1 Steam Generator Sample Selection.
and Inspection - Each steam generator shal be cezermined OPER"BLE during shutoown oy selecting and inspecting at least the minimum number of steam generators specified in Table 4.4-1.
4.4.5.2 Steam Generato~
Tube Sample Selec"'.on and Inscection - The steam generator t:uoe minimum sample size,
- Isoection resu z classif',cation, and the corresponding action required shaii
".e as soecified in Table 4.4-2.
The inservice inspec.ion of steam generator tubes shall be performed at the frequencies specified in Specification 4.4.5.3 and the inspe ted tubes shall be verified acceptable per the acceptance criteria of Specification 4;4.5.4.
Steam generator tubes shall be examined in accordance with Apoendix IV of the ASHE,Boiler and Pressure Vessel Code - Section XI - "Inservice Insoection of Nuclear Power Plant Ccmoonents" 1974 Edition and Addenda through Summer 1976.
The tubes selected for each inservice inspection shall include at least 3". of the total number of tubes in all steam generators; the tubes selected for these inspections shall be selected on a random basis except:
a.
Mhere experience in similar plants with similar water chemistry indicates critical areas to be.inspected, then at least 50" of the tubes inspected shall be from these critical areas.
iJe~t4ed wa1 1 1.
All previously penetrations
(>ZO")', and NO~
pluf)cd s Jc'tv(d 2.
Tubes in those areas where experience has indicated potential problems.
b.
The first inservice inspection (subsequent to the preservic inspection) of each steam generator shall include:
ST.
LUCIE - UNIT 1
3/4 4-5'
~
REACTOR COOLANT SYSTEM SURVEILLANCE RE UIRBIENTS Continued p'epha a
ai Alpha'r 5;
6.
7.
pefect means an imperfectfon. of such severity that ft exceeds limit.
A tube containing a defect fs defective.
Any tube which does not perm)t the passage of the eddy>>
current inspection probe shall be deemed a defective tube.
~
y P/at J Ja.
Plu in Limit means the imperfection depth t or beyon w
ch the cu e shall be removed from service because it ma
~et h'<<<
become unserviceable prior to the next inspection and fs
<y '<<e>
equal Co 40%>> of the nominal tube wall thickness.
Unserviceable describes the condition of a tube ff ft leaks
~ttf tta ttt tt t.tt t
t integrity fn the event of an Operatfng Basfs Earthquake, a
loss-of-coolant accident. or a steati lfnt or feedwater line break as specfffed fn 4.4.5.3.c, above.
b.
4.4.5.5 a.
b.
8.
Tube Ins ectfon means an inspection of the steam generator cu e rom the point of entry (hot leg sfde) completely around the U-bend to the top support of the cold leg.
The steam generator shall be determfned OpERABLE after completfng" the corresponding actions (plu all tubes exceeding the gpss aa 1 fmft and all. tubes contafnfng hrough-wall cracks) required by Table 4.4-2.
~Re orts following each fnservfce t
pectfon of steam generator
- tubes, the
'umber of tubes plugged each steam generator shall be reported to the Camfssfon within 15 days.
The complete results of the steam generator tube fnservfce inspec-tion shall be included fn the Annual Operatfng Report for the period fn which this inspection was completed.
Thfs report shall include:
T.
Number and extent of tubes inspected.
2.
Locatfon and percent of wall-thickness penetration for each fndfcatfon of an imperfection.
3.
Identfffcatfon of tubes plugg
~< z/ecvcd This 40'X plugging limit fs not applicable durfng the cycle 7 operation up to June 30, 1986. If at any Cime during this perfod the unit enters any Nodes other than Nodes 1 and 2, or Node 3 for greater than 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, the unit shall b
placed in cold shutdown and the Cubes with fndfcatfons greater than 40% through-wall penetration shall be removed froe service prior Co exceeding 200'F ST.
LUCIE - UNIT 1 3/4 4-8 Amendment No.
73
Insert for page 3/4 4-8 J
- 9. ~Sleevin means that tube sleeving is permitted, using an approved design sleeve, in areas where the'leeve spans the tubesheet area and whose lower joint is at the primary tubesheet face.
IJ I
EACTOR COOLANT SYSTEM BASES 3/4.4.5 STEAM GENERATORS Continued or ryss'r steam generator tube examinations.
Pluggfng tubes with imperfections exceeding the plug definition of Specification I.4.5.1.a fs 4
.thickness.
Steam generator tube inspection demonstrated the capability to reliably de penetrated 20% of the original tube wall t f ng faft which, by the of the tube nominal wall of operating plants have t degradatfon that has ckness.
The plant fs expected to be operated in a manner such that the secondary coolant will be maintained within those parameter limits found to result in negligible corrosion of the steam generator tubes.
If the secondary coolant chemistry fs,not maintained within these parameter
- limits, localized corrosion may likely result fn stress corrosion cracking.
The extent of cracking during plant operation would be limited by the limitation of steam generator tube leakage between the primary coolant system and the secondary coolant system (primary-to-secondary leakage
~
1 gallon per minute, total).
Cracks having a prfmary-io-secondary leakage less than this limit during operation will have an adequate margin of safety to withstand the loads imposed during normal operation and by postulated accidents.
Operating plants have demonstrated that prfmary-to-secondary leakage of 1 gallon per minute can readily be detected by radiation monitors of steam generator blowdown.
Leakage fn excess of this limit will require plant shutdown and an unscheduled inspection, during which the leaking tubes will be located and plugged.
wastage-type defects are unlikely wfih the a 1 volatile treatment (AVT) of secondary coolant.
However, even ff a feet of sfmflar type should develop fn service. ft will be found durf g scheduled fnservfce wf1 be required of all or SjeCvl g
ST.
LUCIE - UNIT 1 B 3/4 4-3 Amendment No.
69
ATTACHMENT 2 SAFETY ANALYSIS INTRODUCTION The St. Lucie Unit 1 Updated Final Safety Analysis Report (UFSAR) describes the steam generators as vertical U-tube heat.exchangers which transfer the heat generated in the reactor coolant system to the secondary system.
Reactor coolant enters the steam generator through the 42 inch I.D.
inlet nozzle, flows 'through 3/4 inch O.D.
by.049 inch wall tubes and leaves through two 30 inch I.D.
outlet nozzles.'ach steam generator, including U-tubes, is designed for the transients listed in section 5.2.1 and 5.5.1.1a through d of the UFSAR such that no component is stressed beyond the allowable limit as described in the American Society of Mechanical Engineers (ASME)
- Code,Section III. In addition to the normal transients, the additional abnormal transients of Section 5.5.l.le of the UFSAR were also considered in arriving at a satisfactory usage factor as defined in Section III of the ASME Code.
The unit is capable of withstanding these conditions for. the
, prescribed number of cycles in addition to the prescribed operating conditions without exceeding
'the allowable usage factor as prescribed in the ASME Code,Section III.
The purpose of this safety analysis is to address the potential safety impact of steam generator tube sleeving at St.
Lucie Unit 1.
This proposed license amendment addresses sleeves manufactured by both Westinghouse and Combustion Engineering.
The operation of Pressurized Water Reactor (PWR) steam generators
- has, in some instances, resulted in localized corrosive attack on the inside (primary side) and the outside (secondary side) of the steam generator tubing.
This corrosive attack results in a
reduction in steam generator tube wall thickness.
Steam generator tubing has been designed with considerable margin between the actual wall thickness and the wall thickness required to meet structural requirements.
Historically, the corrective action taken in the event of localized corrosive attack has been to install plugs at,the inlet of the steam generator tubes when the reduction in wall thickness reached a calculated value referred to as the plugging criteria. 'ddy current examination has been used to measure steam generator tubing
'degradation, and the tube plugging criteria account for eddy current measurement uncertainty.
Installation of steam generator tube plugs removes the heat
~ 4
transfer surface of the plugged tube from service and leads to a reduction in the primary coolant flow rate available for core cooling.
Installation of steam generator sleeves does not significantly affect the heat transfer removal capability of the tube being sleeved and a large number of sleeves can be installed without significantly affecting primary flow rate.
Z. Westinghouse The Westinghouse steam generator sleeving program at St. Lucie Unit 1 involves the installation of thermally treated alloy 690 sleeves in both the hot and cold legs of the steam generators.
The steam generator tubes to be sleeved are the tubes in which tube degradation within the tubesheet and just above the top of the tubesheet has exceeded the Technical Specification plugging limit of 404 of the nominal tube wall thickness.
Also, tubes in which such a level of degradation is possible in the future may be sleeved in anticipation of such degradation.
The sleeves span from the end of the tube, at the bottom surface of the tubesheet; to a point above the secondary side of the tubesheet.
The sleeves to be used in the sleeving process are long enough in length to span the degraded areas of the tubing,-in the tube sheet region in either the hot or cold legs.
The sleeve is secured in the tube by mechanical joints at the top and bottom of the sleeve.
Tubes to be sleeved are determined by the results and trends of eddy current test (ECT) indications.
Tooling access, i.e., location of the tube within the tube sheet, is also considered in determining tubes to be sleeved.
The St. Lucie Unit 1 steam generators are currently analyzed to 15 percent steam generator tube plugging (SGTP).
This safety analysis supports the installation of the maximum number of sleeves
- expected, as defined and described in Attachment 4, in each of the two steam generators.
This analysis has as a basis that an equivalent SGTP level of 15 percent of the tubes in any steam generator is not exceeded.
To maintain tube integrity consistent with the margin of safety used as the basis for the Technical Specification, allowable levels of tube wall degradation, referred to as plugging limits, are established.
Tubes which have ECT indications of degradation in excess of the plugging limits must be repaired or plugged.
The information provided in Attachment 4 defines the portion of the tube and sleeve for which indications of wall degradation must be evaluated.
This information can be summarized as follows:
1)
Indications of degradation in the entire length of the sleeve must be evaluated against the sleeve plugging limit.
2)
Indication of tube degradation of any
- type, including a
complete guillotine break in the tube between the bottom of the upper joint and the top of the lower roll expansion, does
IIg 4
I A
4 not require that the tube be removed from service.
3)
The Technical Specification tube plugging limit continues to apply to the portion of the tube on the upper joint and in the lower roll expansion.
As noted
- above, the sleeve plugging limit applies to these
- areas, also.
4)
The Technical Specification tube plugging limit continues to apply to that portion of the tube above the top of the upper joint.
The Code of Federal Regulations, 10 CFR 50.55a, requires that components which are a part of the primary pressure boundary be built to the requirements of Section III of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code.
Section 5.2.1.1 of the Standard Review Plan (SRP)
(NUREG-0800),
entitled "Compliance with the Codes and Standards
- Rule, 10 CFR 50.55a",
addresses evaluations to be done by the NRC Staff of the standards used.
Any modifications, repair or replacement of these components must also meet the requirements of the Code to assure that the basis on which the unit was evaluated is unchanged.
Regulatory Guide 1.121, Basis for Plugging Degraded PWR Steam Generator
- Tubes, is used as the basis to determine the sleeve plugging limit.
Regulatory Guide 1.83, Inservice Inspection of Pressurizer Water Reactor Steam Generator
- Tubes, is used as the basis to determine the inspection requirements for the sleeve.
The implementation of the sleeving installation program at St.
Lucie Unit 1
has been reviewed for its impact on safe plant operation, i.e.,
maintenance of steam generator tube integrity.
The sleeve design and installation process has been qualified through laboratory testing and actual field performance as discussed in Attachment 4.
Analytical verification per Attachment 4
has been performed using design and operating transient parameters selected to envelope loads imposed during normal operating,
- upset, and accident conditions at St.
Lucie Unit 1.
Fatigue and stress analyses of sleeved tube assemblies have been completed in accordance with the requirements of the ASME Boiler and Pressure Vessel
- Code,Section III.
The results of the qualification testing,
- analyses, and plant operating experience demonstrate that the sleeving process is an acceptable means of maintaining steam generator tube integrity.
Laboratory testing and previous field experience have shown that the sleeving assemblies can be monitored through periodic inspections with ECT techniques per Regulatory Guide 1.83 recommendations.
Also, the pertinent portions of the tube behind the sleeve can be inspected using available ECT techniques.
The function of the sleeve is to restore the integrity of the tube pressure boundary in the region between the sleeve joints.
The sleeve has been designed and analyzed in accordance with the applicable sections of the ASME Boiler and Pressure Vessel Code including the implicit safety factors.
The sleeve has been shown not to have stress levels in excess of appropriate limits for normal and postulated accident loading conditions for the analytical case of a complete guillotine break in that portion of the tube between the joints.
To determine the basis for the sleeve plugging limits, the minimum wall thickness was calculated in accordance with the recommendations of Regulatory Guide 1.121.
The definition of the areas to which the plugging limit applies to the sleeve and to the sleeved portion of the tube as defined in Attachment 4,
and outlined above, is consistent with the design evaluation and this safety analysis.
The application of the plugging limit definition contained in Attachment 4 does not result in the possibility of an accident not previously analyzed.
Use of the ASME Code and Regulatory Guide 1.121 for the design and evaluation of the sleeves will provide for a possibility of failure no greater than that of the original tubes.
For both cases, the margin of safety is provided in part by the safety factors and assumptions in the ASME Code and Regulatory Guide 1.121.
The installation of a sleeve in a tube results in an additional flow restriction within the primary system with an associated increase in pressure drop in the steam generator.
The effect of this flow restriction on plant operation is evaluated in the same manner that tube plugging effects are analyzed.
Attachment 4
identifies the reduction in primary coolant flow caused by the projected sleeving under normal operating conditions and identifies the number of sleeves which result in a flow reduction equivalent to one plugged tube.
The postulated accidents assessed for the impact of sleeving include both Loss of Coolant Accident (LOCA) and non-LOCA transients.
The existing large break LOCA analysis with the basis of a 15 percent.
SGTP will bound the effects on all core and system parameters for a combination of plugging and sleeving up to 15 percent equivalent SGTP.
This analysis and the corresponding non-LOCA evaluation are considered applicable for the steam generator sleeving program with a combination of plugging and sleeving flow restriction equal to or less than the restriction due to 15 percent tube plugging.
Based on the use of 15 percent SGTP in the Emergency Core Cooling System (ECCS) performance
- analysis, the effect of a
combination of plugging and sleeving up to the equivalent of 15 percent tube plugging would not be expected to result in any design or regulatory limit being exceeded.
To evaluate the effect of sleeving on the non-LOCA transient 4
I
analyses and design transient assumptions have been made.
evaluations, the following The level of sleeving and plugging discussed in this report will not result in a Reactor Coolant System (RCS) flow rate less than the minimum flow rate required by the Technical Specifications.
2.
Operation at the RCS flow rate specified in the Technical Specification is bounded by the non-LOCA safety analyses and design transients.
3.
,With the reduced RCS flow rate greater than or equal to the minimum flow rate specified in the Technical Specification, the effect of anticipated maximum amount of steam generator tube sleeving on the non-LOCA. safety analyses is bounded by the existing analyses.
Therefore, a combination of steam generator sleeving and plugging up to the equivalent of 15 percent plugging would not invalidate any non-LOCA safety analyses.
Also, the design transients are established based on an assumed minimum flow.
Any combination of plugs and sleeves which does not result in an RCS flow rate less than that specified in the Technical Specification would not have an adverse, effect on the evaluation of the design transients.
Any smaller number of sleeves would have less of an effect.
The consequences of the installation of sleeves can be summarized as a restriction of the flow through steam generator tubes, a small reduction in primary volume, and a small reduction in the heat transfer capacity of the tube bundle.
The'ffect, of the restriction of the primary coolant flow can be bounded by the results of the tube plugging evaluation.
The reduction in primary volume results in a smaller mass energy release-.
Typically, in the accident
- analyses, the heat transfer area is not limiting so the small reduction in heat transfer capacity is not significant.
Additionally, the limiting location for counter-current flow during the steam generator drain-down phase of the small break LOCA analysis, is typically not in the steam generator tubes.
The effects of sleeving on LOCA and non-LOCA transient analyses have been assessed.
No adverse result is indicated for. sleeve and plug combinations up to an equivalent of 15 percent SGTP.
The existing ECCS performance analysis and the corresponding non-LOCA evaluation are considered applicable to the steam generator sleeving program with a combination of plugging and sleeving flow restriction equal
'o or less than 15 percent tube plugging.. Steam generator sleeve installation up to the equivalent of 15 percent plugging would not be expected to invalidate any non-LOCA safety analyses or the evaluation of design transients.
Because the projected fluid velocities of Attachment 4 are less than the inception velocities for fluid impacting, cavitation, and
V I
N
> ~
pl
erosion-corrosion, the potential for tube degradation due to these mechanisms is low.
Accordingly, using the above assumptions, no ECCS results more adverse than those in the existing St. Lucie Unit 1 safety analysis are expected for equivalent tube plugging projected to occur at St.
Lucie Unit 1.
For a level of sleeving in combination with tube plugging bounded by existing analysis for 15% tube plugging, the consequences of an accident are not increased.
Any hypothetical sleeve failure is bounded by the consequences of a tube rupture.
II. COMBUSTION ENGINEERING The sleeve dimensions, materials, and joints were designed to the applicable ASME Boiler and Pressure Vessel Code.
An extensive analysis and test program was undertaken to prove the adequacy of the welded sleeve.
This program determined the effect of normal operating and postulated accident conditions on the sleeve-tube
- assembly, as well as the adequacy of the assembly to perform its intended function.
Design criteria were established prior to performing the analysis and test program which, if met, would prove that the welded sleeve is an acceptable repair technique.
Based upon the results of the analytical and test programs described in detail in Attachment 6, the welded sleeve fulfills its intended function as a leak tight structural member and meets or exceeds all the established design and operating criteria.
The installation of welded tube sleeves will'e performed in a
manner consistent with the applicable standards, will preserve the existing design
- bases, and will not adversely impact the qualification of any plant systems.
This will preclude adverse control/protection systems interactions.
The design, installation and inspection of the welded sleeve will be done in accordance with ASME Boiler'nd Pressure Vessel Code criteria.
By adherence to industry standards, the pressure boundary integrity will be preserved.
The installation of a sleeve in a steam generator tube increases the flow resistance through the sleeved tube.
To determine the effect of installing welded sleeves in the steam generators, an analysis was performed and is detailed in Attachment 6.
A conservative sleeve length was used in evaluating the effects of the sleeves on the heat transfer and hydraulic capabilities of the steam generators.
Using the head and flow.characteristics of each of the four primary pumps in conjunction with the primary system hydraulic resistances, the flow rate was calculated as a function of the number of sleeved tubes.
The St.
Lucie Unit 1 Technical Specification minimum allowable flow rate was used to determine the maximum number of tubes per steam generator which can be sleeved at both sides.
The change in primary system flow rate based on the
maximum number of. tubes which can be sleeved per steam generator was calculated to be 2.6 percent.
. The steam generator has been designed to ensure that critical vibration frequencies will be well out of the forcing function frequency range expected during normal operation and abnormal conditions.
The steam generator tubing and tubing supports are designed and fabricated with consideration given to both the normal operation and abnormal conditions secondary-side flow-induced vibrations.
In addition, the heat transfer tubing and tube supports are designed such that they will not be structurally damaged under the loss of secondary pressure conditions that may produce a fluid velocity in the tube bundle four times the design velocity.
The effect of the change in flow rate on heat transfer between the primary and secondary side of the steam generator was determined to be negligible.
The overall resistance to heat transfer between
,the primary and secondary sides consists of the primary side film resistance, the resistance to heat transfer through the tube wall, and the secondary side film'esistance.
Since the primary side film resistance is only a small portion of the total resistance, the effect of the calculated maximum change in flow rate on heat transfer is negligible.
The loss in heat transfer area associated with sleeving was also determined to be small.
When the sleeve is installed in the steam generator tube, there is an annulus between the sleeve and the tube except in the sleeve to tube weld regions.
- Hence, there is effectively little primary to secondary heat transfer in the region where the sleeve is installed.
However, since negligible heat is transferred in the tubesheet region
- anyway, the loss in heat transfer area associated with sleeving is also negligible.
III'ONCLUSION Based on the above, the sleeve design and installation processes have been verified by analytical methods, laboratory testing, and installations at other facilities.
Any combination of sleeving and plugging used at St. Lucie Unit 1 up to the allowable 15 percent equivalent SGTP limit in any steam generator is bounded by the analyses for 15 percent tube plugging.
Installation of the sleeves in the St.
Lucie Unit 1 steam generators will provide a primary system boundary equivalent to that of the original steam generator tube and will not adversely affect the safe operation of the steam generators.
( p II I
V
- I
ATTACHMENT 3 DETERMINATION OF NO 81GNIFICANT HAZARDS CONSIDERATION The standards used to arrive at a determination that a request for amendment involves no significant hazards consideration are included in the Commission s regulation, 10 CFR 50.92, which states that no significant hazards considerations are involved if the operation of the facility in accordance with the proposed amendment would not (1) involve a significant increase in the probability or consequences of an accident previously evaluated; or (2) create the possibility of a new or different kind of an accident previously evaluated; or (3) involve a significant reduction in a margin of safety.
Each standard is discussed as follows:
(1)
Operation of the facility in accordance with the proposed amendment would not involve a significant increase in the probability or consequences of an accident previously evaluated.
The repair of degraded steam generator tubes using sleeves will result in tube bundle integrity consistent with the original design basis.
The sleeve configuration has been designed and analyzed in accordance with the rules of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code.
Fatigue and stress analyses of the sleeved tube assemblies produced acceptable results.
Mechanical testing has shown that the structural strength of the sleeves under
- normal, faulted and upset conditions is within acceptable limits.
Leak rate testing has demonstrated that the leak rates of the joints between the sleeve and the existing tube under normal, faulted and upset conditions are well below acceptable rates.
The existing Technical Specification leakage rate requirements and accident analysis assumptions remain unchanged in the event significant leakage from the sleeve would occur.
Any leakage through the sleeved region of the tube due to potential localized tube degradation is fully bounded by leak-before-break considerations and ultimately by the existing steam generator tube rupture analysis included in the St.
Lucie Unit 1
Updated Final Safety Analysis Report.
The proposed Technical Specification change to support the installation of mechanical joint sleeves does not adversely impact any other previously evaluated design basis accident or the results of Loss of Coolant Acccident (LOCA) and non-LOCA analyses.
The results of the qualification testing,
- analyses, and plant operating experience demonstrate that the sleeve assembly is an acceptable means of maintaining tubes in service.
Furthermore, per U.S.
Nuclear Regulatory Commission Regulatory Guide 1.83 recommendations, the sleeved
tube can be monitored through periodic inspections with present eddy current techniques.
Plugging limit criteria are established in the Technical Specifications for the tube in the region of the sleeve and the sleeve.
These measures demonstrate that installation of sleeves which span degraded areas of the tube will restore the tube to its original design basis.
The sleeve dimensions and joints were designed to the'pplicable ASME Boiler and Pressure Vessel Code.
An extensive analysis and test program was undertaken to prove the adequacy of the welded sleeve.
This program determined the effect of normal operating and postulated accident conditions on the sleeve-tube
- assembly, as well as the adequacy of the assembly to perform its intended function.
Design criteria were established prior to performing the analysis and test program which, if met, would prove that the welded sleeve is an acceptable repair technique.
Based upon the results of the analytical and test programs, the welded sleeve fulfills its intended function as a leak tight structural member and meets or exceeds all the design and operating criteria.
(2)
Operation of the facility in accordance with the proposed amendment would not create the possibility of a
new or different kind of accident from any accident previously evaluated.
Implementation of the proposed tube degradation repair method does not introduce significant changes to the plant design bases.
Repair of tubes does not provide a mechanism to result in an accident outside of the sleeved area.
Any hypothetical accident as a result of potential tube or sleeve degradation in the repaired'ortion of the tube would be bounded by the existing tube rupture accident analysis.
The installation of welded tube sleeves does not create the possibility of a new or different kind of accident from any previously analyzed.
The installation of welded tube sleeves will be performed in a
manner consist with the applicable standards, will preserve the existing design bases, and will not adversely impact the qualification of any plant systems.
This will preclude adverse control/protection systems interactions.
The design, installation and inspection of the welded sleeve will be done in accordance with ASME Boiler and Pressure Vessel Code criteria.
By adherence to industry standards, the pressure boundary integrity will be preserved.
As
- such, the possibility of a
new or different kind of accident is not created.
(3)
Use of the modified specification would not involve a
significant reduction in a margin of safety.
I tg yl (I
I 4 ~
The effect of sleeving on the design transients and accident safety analysis has been reviewed based on the installation of the maximum number of sleeves expected.
The installation of sleeves can be evaluated as the equivalent of some level of steam generator tube plugging.
The St. Lucie Unit 1 steam generators are currently licensed to 15 percent steam generator tube plugging (SGTP).
Evaluation of the installation of sleeves is based on assuming that LOCA evaluations for 15 percent tube plugging bound the effect of a
combination of tube plugging and sleeving up 'to an equivalent of 15 percent SGTP.
For the purpose of assessing the impact on the non-LOCA safety analyses and the design transients, it is assumed that the reactor coolant flow rate used for these analyses and transients is less than that which results from 15 percent equivalent SGTP.
Given that the reactor coolant flow rate up to 15 percent equivalent SGTP is greater than the flow rate used for the these
- analyses, the non-LOCA safety analyses and design transients are not adversely impacted by steam generator sleeving.
The safety margins in the analyses of postulated accident conditions and design transients are provided in the assumptions and conservatism in the calculations and computer codes used and in the requirements and recommendations of the NRC.
Accordingly, based on the information outlined above, there is no decrease in the safety margins defined in the basis of the plant Technical Specifications.
Implementation of tube repair by sleeving will decrease the number of tubes which must be taken out of service with tube plugs.
Installation of tube plugs reduces the Reactor Coolant System (RCS) flow margin, thus implementation of tube repair by sleeving will maintain the margin of flow that would otherwise be reduced in the event of increased plugging.
Based on the above, it is concluded that the proposed change does not result in a significant reduction in a loss of margin with respect to plant safety as defined in the Updated Final Safety Analysis Report or the basis for the St. Lucie Unit 1 Technical Specifications.
The installation of a
sleeve in a
steam generator tube increases the flow resistance through the tube.
The increase resistance may result in reduced flow through the sleeved tube.
To determine the effect of installing welded sleeves in the steam generators, an analysis was performed.
A conservative sleeve length was used in evaluating the effects of the sleeves on the heat transfer and hydraulic capabilities of the steam generators.
Using the head and flow characteristics of each of the four primary pumps in conjunction with the primary system hydraulic resistances, the flow rate was calculated as a function of the number of
sleeved tubes.
The Technical Specification minimum allowable flow rate was used to determine the maximum number of tubes per steam generator which can be sleeved at both hot and cold legs.
The change in primary system flow rate based on the maximum number of tubes which can be sleeved per steam generator was calculated to be 2.6 percent.
The effect of the change in flow rate on heat transfer between the primary and secondary side of the steam generator was determined to be negligible.
The overall resistance to heat transfer between the primary and secondary sides consists of the primary side film resistance, the resistance to heat transfer through tube
- wall, and the secondary side film resistance.
Since the primary side film resistance is only a small portion of the total resistance, the effect of the calculated maximum change on flow rate on heat transfer is negligible.
The loss in heat transfer area associated with sleeving wa's also determined to be small.
When the sleeve is installed on the steam generator
- Hence, there is effectively little primary to secondary heat transfer in the region where the sleeve is installed.
However, since negligible heat is transferred in the tubesheet region anyway, the loss 'in heat transfer area associated with sleeving is also negligible.
Based on the above, we have determined that the amendment request does not (1) involve a significant increase in the probability or consequences of an accident previously evaluated, (2) create the probability, of a
new or different kind of accident from any accident previously evaluated, or (3) involve a
significant reduction in a margin of safety; and therefore does not involve a significant, hazards consideration.
ATTACHMENT 4 St. Lucie Unit 1 Steam Generator Sleeving Report (Mechanical Sleeves)
%CAP - 12076
ATTACHMENT 7 Affidavit Pursuant to 10 CFR 20790 re:
CEN 377 (F) - P; St. Lucie Unit 1 Steam Generator Tube Re air Usin Leak Ti ht Sleeves
AFFIDAVITPURSUANT TO 10 CFR 2.790 Combustion Engineering, Inc.
)
State of Connecticut
)
County of Hartford
)
SS.:
I, A. E. Scherer, depose and say that I am the Director, Nuclear Licensing, of Combustion Engineering, Inc., duly authorized to make this affidavit, and have reviewed or caused to have reviewed the information which I
4 l's identified as proprietary and referenced in the paragraph immediately below.
I am submitting this affidavit in conformance with the provisions of 10 CFR 2.790 of the Commission's regulations for withholding this information.
The information for which proprietary treatment is sought is contained in the following document:
CEN-378(L)-P, "St. Lucie Unit 2 Steam Generator Tube Repair Using Leak Tight Sleeves",
July 1988.
This document has been appropriately designated as proprietary.
I have personal knowledge of the criteria and procedures utilized by Combustion Engineering in designating information as a trade secret, privileged or as confidential commercial or financial information.
Pursuant to the provisions of paragraph (b) (4) of Section 2.790 of the Commission's regulations, the following is furnished for consideration by the Commission in determining whether the information sought to be withheld from public disclosure, included in the above referenced
- document, should be withheld.
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1.
The information sought to be withheld from public disclosure is a description of the design, manufacture,
- testing, and installation of steam generator tube welded sleeves, which is owned and has been held in confidence
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by Combustion Engineering.
2.
The information consists of test data, or. other similar data concerning a
I
- process, method or component, the application of which results in substantial competitive advantage to Combustion Engineering.
3.
The information is of a type customarily held in confidence by Combustion Engineering and not customarily disclosed to the public.
Combustion Engineering has a rational basis for determining the types of information customarily held in confidence by it and, in that connection, utilizes a system to determine when and whether to hold certain types of information in confidence.
The details of the aforementioned system were provided to the Nuclear Regulatory Commission via letter DP-537 from F. M. Stern to Frank Schroeder dated December 2, 19?4.
This system was applied in determining that the subject document herein are proprietary.
4.
The information is being transmitted to the Commission in confidence under the provisions of 10 CFR 2.790 with the understanding that it is to be received in confidence by the Commission.
5.
The information, to the best of my knowledge and belief, is not available in public sources, and any disclosure to third parties has been made pursuant to regulatory provisions or proprietary agreements which provide for maintenance of the information in confidence.
6.
Public disclosure of the information is likely to cause substantial harm to the competitive position of Combustion Engineering because:
4 f
a.
A similar product is manufactured and sold by major pressurized water reactor competitors of Combustion Engineering.
b.
Development of this information by C-E required tens of thousands of manhours of effort and millions of dollars.
To the best of my knowledge and belief a competitor would have to undergo similar expense in generating equivalent information.
c.
In order to acquire such information, a competitor would also require considerable time and inconvenience related to the development of the
- design, manufacture, testing, and installation of steam generator tube welded sleeves.
d.
The information required significant effort and expense to obtain the licensing approvals necessary for application of the information.
Avoidance of this expense would decrease a comp'etitor's cost in applying the j
information and marketing the product to which the information is applicable.
t e.
The information consists of a description of the design,
'anufacture,
- testing, and installation of steam generator tube welded sleeves, the application of which provides a competitive economic advantage.
The availability of such information to competitors would enable them to modify their product to better compete with Combustion Engineering, take marketing or other actions to improve their product's position or impair the position of Combustion Engineering's product, and avoid developing similar data and analyses in support of their processes, methods or apparatus.
f.
In pricing Combustion Engineering's products and services, significant research, development, engineering, analytical, manufacturing, licensing, quality assurance and other costs and expenses must be included.
The ability of Combustion Engineering's competitors to utilize such
t'4
information without similar expenditure of resources may enable them to sell at prices reflecting significantly lower costs.
g.
Use of the information by competitors in the international marketplace would increase their ability to market nuclear steam supply systems by reducing the costs associated with their technology development.
In addition, disclosure would have an adverse economic impact onCombustion Engineering s potential for obtaining or maintaining foreign licensees.
Further the deponent sayeth not.
l Sworn to before me thing~day of
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'r Notary<'Public PTAS PUB r'~ SUSANHE SMLTH 74148 ot CorrAac Expires Starch 31, 1990 0rrrrrrlsslorr ir A. E.
cherer Director Nuclear Licensing
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