ML20078R588
| ML20078R588 | |
| Person / Time | |
|---|---|
| Site: | LaSalle  |
| Issue date: | 11/12/1983 |
| From: | Schroeder C COMMONWEALTH EDISON CO. |
| To: | Harold Denton Office of Nuclear Reactor Regulation |
| References | |
| RTR-NUREG-0578, RTR-NUREG-578 7608N, NUDOCS 8311150215 | |
| Download: ML20078R588 (10) | |
Text
,.
- s' t
Commonwealth Edison
') ons First National Plan. Chic"go, lilenois
- \\ C Address Riply to: Post Offico Box 7fd N
Chicago. lilinois $290 November 12, 1983 Mr. Harold R. Denton, Director Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, DC 20555
Subject:
LaSalle County Station Units 1 and 2 SSER 5 Appendix C Erratta NRC Docket Nos. 50-373 and 50-374 Reference (a):
NUREG 0578, Supplement 5, Appendix C Evaluation of Relief Requests for Inservice Inspection Program Units 1 and 2.
Dear Mr. Denton:
Our review of Reference (a) identified a number of,
typographical errors which need correcting to provide a correct and complete reference for future ISI work.
These errors are corrected on the attached marked-up pages.
Additionally, three apparent omissions on our part are added to the list.
On page C8, Commonwealth Edison takes exception to the statement made that we agreed to surface (PT) examinations for given piping which was inaccessible or impractical (high radiation) to examine with ultrasonic techniques.
The matter is one of inaccessi-bility and extreme radiation, not one of examination technique.
Our position is as stated in the corrected paragraph and we believe it meets the code and intent of 10 CFR 50.55a(g)(6)(1) as explained in the Conclusions to this appendix.
i To the best of my knowledge and belief the statements contained herein and in the attachments are true and correct.
In some respects these statements are not based on my personal know-ledge but upon information furnished by other Commonwealth Edison i
and contractor employees.
Such information has been reviewed in l
accordance with Company practice and I believe it to be reliable.
If there are any further questions in this matter, please contact this office.
Very truly yours, lt/ B3 8311150215 831112
~
H
$DRADOCK 05000373 j
PDR C.
W. Schroeder Nuclear Licensing Administrator
[
cc:
NRC Resident Inspector - LSCS l
7608N.
t APPENDIX C EVALUATION OF RELIEF REQUESTS FOR INSERVICE INSPECTION PROGRAM FOR UNITS 1 AND 2 I.
INTRODUCTION The La Salle County Station Unit 1 operating license was issued on April 17, 1982.
The La Salle County Station Unit 2 construction permit was issued on September 10, 1973.
Section 10 CFR 50.55a(g)(4) requires that throughout the service life of a boiling or pressurized water-cooled nuclear power facility, components (including supports) which are classified as ASME Code Class 1, 2 and 3 shall meet the requirements set forth in the applicable Section XI Editions and Addenda of the ASME Boiler and Pressure Vessel Code to the extent practical within the limitations of design, geometry and materials of construc-tion of the components.
Paragraph 10 CFR 50.55a(g)(4) also requires that inservice examinations of components and system pressure tests during the initial 10 year inspection interval shall comply witn the requirements set forth in editions of Section XI of the ASME Code and Addenda in effect 12 months prior to the date of issuance of the operating license.
Paragraph 10 CFR 50.55a(g)(6)(i) authorizes the Commission to grant relief and to impose alter-native requirements upon making the necessary findings.
In letters dated July 13, 1982 and December 21, 1982, CECO submitted the initial ten year inservice inspection programs for Units 1 and 2 respectively.
The inservice inspection programs for both Units 1 and 2 are based on the 1980 Edition including Addenda through Winter 1980.
II.
EVALUATION OF RELIEF REQUESTS Ceco requested relief from specific Section XI inservice inspection requirements which have been determined to be impractical to perform at La Salle County Station, Units No. 1.and 2.
In cases where part of the required examination cannot be effectively performed because of a combination of component design or limitations in current inspection techniques, we will continue to evaluate the development of new or improved volumetric examination techniques.
As improve-ments in these areas are achieved, we will require that these new techniques be made a part of the updated inservice examination programs of those components or welds which received a limited examination.
The following paragraphs discuss details of each specific relief request.
Unless otherwise noted, all relief requests apply to both La Salle Units 1 and 2.
References to the Code refer to the American Society of Mechanical Engineers Code,Section XI, 1980 Edition including Addenda through Winter 1980.
The numbering designations are not sequential because CECO deleted several items that were applicable only to the preservice inspection.
La Salle SSER 5 C-1
A.
Circumferential Butt Welds in Primary Containment Penetrations, Examination Category B-J (Relief Requests RI-05 ancGotT7) g ]\\
Code ' Requi rement':
A surface examination and a volumetric examination of the lower one-third of the weld volume is required.
Code Relief Request:
Relief was requested from performing the entire surface and volumetric examination required by the Code.
Reason for Request
Due to its design, the primary containment pene-tration assembly leaves one pressure-retaining piping weld inacces-sible for examination by either surface or volumetric methods.
A volumetric examination consisting of a radiographic examination was performed during fabrication to meet Section III requirements.
These fabrication documents are available for audit at La Salle County Station.
The~ welds can only be examined by inspecting for evidence of.-leakage during system hydrotests.
CECO proposed a visual examina-
. tion for leakage during a system hydrostatic test as an alternative
, examination.
A surface examination for the circumferential butt weld
' on the reactor core isolation cooling system penetration was proposed to be performed.
Staff Evaluation:
During our review of the inservice inspection program for Unit 2, we noted that RI-11 is included in the list of Relief Requests under Tab #6; however, RI-11 was not applied in the detailed sampling list in Tab #5.
Therefore, we concluded that RI-11 was not applicable to Unit 2.
'The circumferential butt weld on the primary containment penetrations that is required to be examined by the Code is physically inaccessible for inspection because of the' existing design. The circumferential butt welds between the containment penetration sleeve and the flued head fitting are located in the following penetration lines:
Unit 1 IMS01BA 1MS01EB*1A*
02FA*1A*
1MS01BB 1M501EC*1A*
1FWO2FB*1A*
IMS01BC 1MS01E0*1A*
1R101A*1A*
IMS01BD IMS01EA*1A*
. Unit 2 2FWO2FA*1A*
2MS01AB 2MS01BA 2FW02FD*1g*
2MS01AC 2MS01BB 2M501AA 2MS01AD 2M501BC 2MS01BD Imes w ifh The designation
- Type
- refers to welds included in the augmented inservice inspection program.
La Salle SSER 5 C-2
We have determined that part of the required Section XI examination is impractical because the existing geometric configuration limits the extent of the examination.
We have also determined that the size of the examination sample should not be reduced as a result of the inaccessible design.
Therefore, the NRC staff will require an augmented inservice inspection program consisting of the volumetric examination of one additional process pipe weld in each of the identi-fied lines, during the required inspection period, in order to main-tain an equivalent sample.
The weld selected for augmented examina-tion should be of the same material type, similar diameter, and simi-lar operating environment as the inaccessible weld subject to examina-tion. We conclude that performing the identified Section XI surface examination, the augmented inservice inspection program, and the hydrostatic test will provide an acceptable level of structural integrity.
B.
ASME' Class 2 Pipe Branch Connections, Examination Category C-F (Relief Request RI-07)
Code Requirement:
A surface examination is required of the pressure retaining branch connection welds.
Code Relief Request:
Relief was requested from performing 100 percent of the Code required surface examination.
Reason for Request
The branch pipe connection lines listed below are constructed with rc'nforcement saddles.
These saddles are fillet welded over the actual t anch connection weld.
Therefore, a surface examination cannot be performed on the branch connection weld.
Staff Evaluation:
The existing design makes the pipe branch connec-tions listed below physically inaccessible.
The pressure retaining weld required to be examined is totally covered by a reinforcement saddle.
CECO proposes to perform a surface examination of the all reinforcement saddle to process pipe welds as an alternative examination.
We have evaluated the subject welds for 'ccessibility on the foli' wing a
lines:
Unit l' 1MS01BA 1MS01BD 1MS01CC 1MS01BB 1MS01CA 1MS03Q{l IMS01BC 1MS01CB Unit 2 2MS01BA 2MS01CA 2MS38AA 2MS01BB 2MSO.1.4 2MS38AB 2M501pd 2MS01.Y 2MS01BD 2MS01CC La Salle SSER 5 C-3 Symme
%w.
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d;[1 t
y y
We have determined that examination of these welds to the extent h
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required by Section XI is impractical due to the location of piping reinforcement saddles and the geometry of fillet welds attaching the saddles to the main pipe.
Q p
We conclude that performing a surface examination of the. saddle gi attachment welds and the hydrostatic test will provide an acceptable p
level of structural integrity.
H-M C.
ASME Class 2 Pressure-Retaining Welds in Unde 1round Piping, k$
Examination Category C-F (Relief Request RI-08)
C Code Requirement:
A surface examination is required on pressure f
retaining welds in piping less than or equal to 1/2 in. nominal wall d
thickness.
h' t
Code Relief Request:
Relief was requested from performing the
@y surface examination required by the Code.
Reason for Request
The underground location of these welds makes a C
surface examination impractical.
CECO proposes as an alternative u
test a visual examination consisting of a pressure leakage test that determines the rate of pressure loss during the system pressure test p
required by Paragraph IWC-5000 of Section XI.
3 Staff Evaluation:
Section IWC-1230 recognizes the impracticality of 7
examination of components encased in concrete.
We have determined 5
that even though IWC-1230 specifies concrete-encased components, the intent may be applied to components that are underground. This I
request applies to the following lines:
Unit 1
- 1HP01A
= 1L^ CIA 1R116A*2A*
I Unit 2 2HP01A 2R116A*2A*
CECO will perform a pressure test of these lines.
We have determined that the Code-required examination is impractical because of the underground location of these welds.
Imposing the Code requirement would result in hardships or unusual difficulties without a compensating increase in quality and safety.
We conclude that performing pressure tests in accordance with IWC-5000 to deter-mine leakage will provide an acceptable level of structural integrity.
D.
Closure Head Nozzle Inner Radius (NIR), Examination Category B-0, Item Bl.4 (Relief Request RI-09)
Code Requirement:
The extent of examination of each nozzle shall cover 100 percent of the volume to be inspected as shown in Sec-La Salle SSER 5 C-4 I
tion XI Figure IWB-25000.
All nozzles shall be examined during each inspection interval.
Code Relief Request:
Relief was requested from performing the 100 percent volumetric examination requirements for nozzle-to-vessel welds N7, N8 and N18 (both units have same designation).
Reason for Request
The reactor pressure vessel (RPV) closure head is removed during refueling activities allowing access to the RPV closure head nozzle inner radius (NIR).
A surface examination is more sensitive than a volumetric examination in detecting surface defects at the NIR.
Approximately 40 man-hours would be required to volumetrically inspect the 3 RPV closure head NIR and bore areas during inservice inspection.
The ultrasonic test (UT) technique employed during the preservice inspection employs five specially contoured variable-angle lucite wedges which track both the radial and circumferential marking lines.
By comparison, only 4 man-hours are required to examine all these areas via liquid penetrant test (PT) techniques. With equivalent radiation levels, the radiation exposure for UT would be ten times the exposure during PT for these inspections.
Staff Evaluation:
We conclude that a surface examination of the nozzle inner radius region and bore areas is more sensitive for detecting. service-induced surface connected defects than UT.
In addition, radiation exposure of inspection personnel will be reduced using PT techniques.
Therefore, we find the surface examination an acceptable alternative examination.
E.
Recirculation Pump Internal Surface and Valve Internal Surface Visual Examination (Relief Requests RI-13 and RI-14)
Code Requirement:
Examination Category B-L Visual examination of I of 2 pumps each 10 year interval.
Examination Category B-M Visual examination of 1 valve in each group of valves (as specified in Category B-M-2) each 10 year interval.
1 Code Relief Request:
Relief was requested to delete the periodic visual examinations as reqLired by the Code.
Reason for Request
i Relief Request 13 - The recirculation pump casing material is cast stainless steel.
This material type has performed very well in nuclear service and has demonstrated substantial resistance to such chemical processes as pitting corrosion and stress corrosion cracking i
which would decrease the structural integrity of the pump.
To do the required visual inspection of this pump's internal surfaces, a large amount of radiation exposure and time would be required.
This was demonstrated at a similar nuclear station, where an expenditure of La Salle SSER 5 C-5 v
e-
~
i approximately 1000 man-hours and 50 man-rem was required to complete the visual inspection of a similarly designed pump.
The large expenditure of man-rem and man-hours to complete the visual j
inspection of this pump is impractical and not commensurate to the increased safety achieved by the inspection. Commonwealth Edison i
believes that adequate safety margins are inherent in the basic pump design and that the health and safety of the public will not be adversely affected by not performing the visual' examination of the pump casing internal surfaces solely for the purpose of inspection.
However, if a pump requires disassembly for maintenance, then a visual inspection, to the extent practical, will be performed.
Relief Request 14 - In Class 1 systems, there are 69 valves in 18 groups which are greater than 4 inches nominal pipe size.
The requirement to disassemble an operable valve for the sole purpose of performing a visual examination of the internal pressure boundary is impractical and not commensurate to the increased safety achieved by the inspection and has only a very small potential of increasing plant safety margins with a very disproportionate impact on expendi-tures of plant man power and radiation exposure.
Performing these visual examinations under such adverse conditions as high dose rate (10 R/hr) and poor as-cast surface condition provides little addi-tional information as to the valve casing integrity.
The performance of both carbon and stainless steel cast valve bodies has been excellent in all boiling water reactor applications.
Common-wealth Edison believes that adequate safety margins are inherent in the basic valve design and that the health and safety of the public will not be adversely affected by not performing the visual inspec-tions of the valve body internal surfaces solely for the purpose of inspection.
However, if a valve requires disassembly for maintenance, then a visual inspection, to the extent practical, will be performed.
Staff Evaluation: We have determined that the disassembly of pumps and valves that are operating within nominal conditions for the sole purpose of a visual examination is impractical and technically unwar-ranted. We have concluded that a visual examination performed in the event of disassembly for maintenance, to the extent accessible, is an acceptable alternative to the Code requirement.
F.
Reactor Pressure Vessel Welds at the Vessel Bottom Head (Relief Request RI-15)
Code Requirement:
The volumetric examination erformed during the first inspection interval shall include the accessible length of all welds.
The Code defines " accessible" to include essentially 100 per-cent of the weld length.
Code Relief Request:
Relief was requested from performing 100 percent of the Code required volumetric examinations.
La Salle SSER 5 C-6
===.
Reason for Request===
These welds are partially or completely inacces-sible due to the control rod drive housings.
A volumetric examination consisting of a radiographic examination was performed during fabri-cation to meet Section III requirements.
These fabrication documents are available at the vessel manufacturer for audit.
The Unit 1 ves-sel was manufactured by Combustion Engineering and the Unit 2 vessel was manufactured by Chicago Bridge and Iron Nuclear.
CECO proposes to perform a visual examination for evidence of leakage during the hydrostatic pressure test.
Staff Evaluation:
The subject welds are:
Unit 1 GEL-IOoto - A p4,CA,CB, CC, CD,f C, C F~, CQ 0:L 1001 ;;
-::L 1;;; ;-
Unit 2~
CEL 1007 GEL-1061 - og DR Volumetric examination to the extent required by the Code of the subject welds is not physically possible due to the design and loca-tion of control rod drive penetrations from the. exterior and core shroud plate from the interior.
We have determined that the required Section XI examination is impractical because the vessel design limits the extent of examina-tion.
We conclude that the Code required hydrostatic test and visual examination for evidence of leakage will provide an acceptable level of structural integrity.
G.
Circumferential and Longitudinal Pipe Welds with Access Limitations (Relief Requests RI-16 and RI-18)'
Code Requirement:
i Examination Category B-J - A surface and/or volumetric examination is required on circumferential and longitudinal pipe welds in accordance with Table IWB-2500-1 of Section XI.
Examination Category C-F - A surface and/or volumetric examination is required of circumferential butt welds.
1 Code Relief Request:
Relief was requested from performing 100 percent of the Code-required examination.
Reason for Request
During our review of the inservice inspection program for Unit 2, we noted RI-18 is included'in the list of Relief Requests under Tab #6; however, RI-18 was not applied in the detailed i
sampling list in Tab #5.
Therefore, we concluded that RI-18 was not j
applicable to Unit 2.
1f I
r l
La Salle SSER 5 C-7
_~
- b The subject welds are inaccessible due to immovable supports, braces,
'hhngers or whip restraints covering the inspection area to such an
~
extent-~that examination to the minimum requirement of the Code (i.e.,
the weld and adjacent base metal) cannot be met.
A volumetric exami-nation was' performed during fabrication to meet Section III require-ments.
These fabrication documents are available for audit at La Salle County Station.
The surface examination required by the Code will be performed on welds that are accessible.
In addition, a visual inspection for evidence of leakage will be conducted during the system hydrotest of IWB-5000.
Staff Evaluation:
We have evalur+.ed the accessibility and inspecta-bility of welds on the following iines:
Unit 1 I sw02EC.
1FWO2EA 1M501AB 1RH19CB 1HP08C 1M501AC 1RR01AA*1A*
1HP09B 1MS01AD 1RR01AB*1A*
ILP06B 1RH01AA 1RR07AA IM501AA 1RH04A
'"' '^^^ --
Unit 2 2FWO2EA 2LP06B 2RH04A 2LP028 % lA M 2M501AB 2RH19CB We have determined that examination of these welds to the extent required by the Code is impractical due to the design of the piping system and/or location of piping hangers and supports.
OEi!U"1rtTT
- . '_;t _ _ c f _;. ;n;r "..
.vua m.um...mim
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uv uno smu s un
^'r' ::r.;t Le sumpiece;, ~...J L.,
th; lu osvoeu inspeudon. We conclude that the limited Section XI examination,
...m f::: ^ ~ # :-
+9eer and the hydrostatic test will demonstrate an acceptable level of structural integrity.
III. CONCLUSIONS Based on the foregoing, we have determined, pursuant to 10 CFR 50.55a(g)(6)(i),
that certain Section XI required inservice examinations are impractical, and compliance with the requirements would result in hardships or unusual diffi-culties without a compensating increase in the level of quality and safety.
Our technical evaluation has not identified any practical method by which the existing La Salle Units 1 and 2 can meet all the specific inservice inspection requirements of Section XI of the American Society of Mechanical Engineers Code.
Requiring compliance with all the existing Section XI required inspec-i tions would require redesign of a significant number of plant systems, obtaining sufficient replacement components, installing the new components, and repeating the preservice examination of these components.
Examples of components that j
would require redesign to meet the specific inservice examination provisions I
are the reactor vessel and a significant number of the piping and component La Salle SSER 5 C-8
4
+ '9 support systems.
Even after the redesign effort, complete compliance with the inservice examination requirements probably could not be achieved.
Based on our review and evaluation, we conclude that the public interest is not served by imposing certain provisions of Section XI of the American Society of Mechanical Engineers Code that have been determined to be impractical and pursuant to 10 CFR 50.55a(g)(6)(i), relief is granted from these requirements.
We conclude that relief granted from the examination requirements and alter-native methods imposed through this document give reasonable assurance of the piping, component pressure boundary and support structural integrity, that granting relief where the Code requirements are impractical is authorized by law and will not endanger life or property, or the common defense and security, and is otherwise in the public interest considering the burden that could result if they were imposed on the facility.
We have determined that granting relief from specific ASME Section XI Code requirements does not authorize a change in effluent types or total amounts nor an 11 crease in power level and will not result in any significant environ-mental i.1 pact.
Having made this determination, we have further concluded that this is an action which is insignificant from the standpoint of environmental impact and, pursuant to 10 CFR 951.5(d)(4), that an environmental impact state-ment or negative declaration and environmental impact appraisal need not be prepared in connection with the grant of this relief.
We have concluded, based on the considerations discussed above, that:
(1) because this action does not involve a significant increase in the probability or consequences of accidents previously considered and does not involve a sig-nificant decrease in a safety margin, the action does not involve a significant hazards consideration, (2) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed man-ner, and (3) such activities will be conducted in compliance with the Commis-sion's regulations and the issuance of this action will not be inimical to the j
common defense and security or to the health and safety of the public, a.
I l
l La Salle SSER 5 C-9 d
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