ML17347A296
| ML17347A296 | |
| Person / Time | |
|---|---|
| Site: | Turkey Point  |
| Issue date: | 02/13/1987 |
| From: | NRC |
| To: | |
| Shared Package | |
| ML17347A295 | List: |
| References | |
| NUDOCS 8703020155 | |
| Download: ML17347A296 (21) | |
Text
ENCLOSURF.
SAFETY EVALUATJON ON REOUESTS FOR RELIEF FROM INSERVICE INSPECTION REQUIREMENTS FLORIW POWER AND LIGHT COMPANY TURKEY POINT UNITS 3 AND 4 DOCKET NOS. 50-250 AND 50-25J I.
BACKGROUND In accordance with 10 CFR 50.55a(g),
Technical Specification 4.? for the Turkey Point Nuclear Generating Station Units 3 and 4 states that inservice examination of ASIDE Code Class I, 2, and 3 components shall be performed to the requirements of Section XI of the ASIDE Boiler and Pressure Vessel Code except where specific written relief has been granted by the Commission.
The regulation (10 CFR 50.55a) also requires that the examination and testina programs be updated every ten-year interval to the latest approved edition and addenda of Section XI in effect 12 months prior to the start of the interval.
However, certain requirements of the later editions and addenda of Section XI are impractical to perform on older plants because of the plants'esign, component
- geometry, and materials of construction.
Recognizing these facts, the regulation authorizes the Commission to grant relief from those-requirements upon making the necessary findings.
By letter dated August 6, 1986, Florida Power and Light Company (the licensee) submitted to the NRC requests for relief from the examination requirements of Section XI of the ASME Boiler and Pressure Vessel Code for the reactor vessel nozzle welds at Turkey Point Units 3 and 4.
The requests had been submitted previously with the ten-year inservice inspection program that was updated to the 1980 Edition through Minter 1981 Addenda of Section XI, but were withdrawn after the stag'equested additional information to support the licensee's determination that the examination requirements were i
8703020155 870213 PDR ADOCK 05000250 8
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impractical to perform.
The information requested by the staff could be obtained by the licensee only when the plants were down and access to the reactor vessel nozzles was permitted.
This information has been provided in attachments to the August 6, 1986 letter and is evaluated in this report to determine if the necessary findings can be made to grant the reliefs as requested.
II.
SL'PPORTING INFORMATION AND EVALUATION OF RELIEF REQUESTS A.
Relief Request No.
12 1.
Components Identification:
Reactor Pressure Vessel Nozzle-to-Safe End Welds and Steam Generator Nozzle-to-Safe End Welds.
Code Class 1
Code Category 8-F Code Item No. 81.6 (Reactor Vessel)
Code Item No. 83.3 (Steam Generators>
Safe End-to-Pipe Welds Code Class 1
Code Category 8-F Code Item No. 84.1
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Examination Requirements t1974 Edition through Summer 1975 Addenda of Section XI)
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1MB-2500 The examinations performed during each inspection interval shall cover the circumference of 100Ã of the welds.
Nozzle safe-end welds require volumetric and surface examination methods.
The area subject to examination shall include the base material for at least one wall thickness beyond the edge of the weld.
3.
Relief Requested a.
Relief is requested from "code volume and surface area not achievable in performance of ultrasonic and surface examination" for the following welds:
H Plant Unit No.
PTP-3 Meld Identification RCC-A-1 RCC-A-14 RCC-8-1 RCC-8-14 RCC-C-1 RCC-C-14 PTP-4 RC-1-1 RC-2-1 RC-2-14 RC-3-1 RC-1-14 RC-3-14 b.
Relief is requested to utilize the later edition of Section XI endorsed by the federal regulations for surface examinations for the following welds:
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PTP-3 Weld Identification RCC-A-1 RCC-A-14 RCC-B-1 RCC-B-14 RCC-C-1 RCC-C-14 PTP-4 RC-1-1 RC-2-1 RC-2-14 RC-3-1 RC-1-14 RC-3-14 RC-3-4 RC-3-5 4.
Licensee's Stated Bases for Requesting Relief l ~
a.
Portions of the required volumetric and surface area are inaccessible due to permanent physical obstructions in the annulus area around the reactor pressure vessel, i.e.,
biological shield wall, insulation brackets, and the structural configuration of the nozzle support lugs.
b.
In order to perform the examinations the sand boxes have to be removed.
c.
FPL performed detailed examinations of all the nozzle welds for Turkey Point 3 in 1975.
These methods included visual, penetrant (both manual and mechanized) and ultra-sonic examinations, mechanized on the hot legs and manual on the cold legs.
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d.
The limitations denoted on Unit 3 are also applicable to Unit 4 as both units are identical in design.
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e.
Performance of these examinations on the nozzles involves excessive
- cost, man-hours and man-rem with little or no compensating increase in the level of quality and safety.
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The extent of surface to be examined has been revised by the later edition and addenda of'ection XI to include the weld plus 4" on each side.
g.
FPL is pursuing an alternate technique utilizina the ultra-sonic method of examining the outside surface of the welds from the inside surface.
This technique is to be used in lieu of the surface examination requirements.
This technique was utilized during the last refuelina outage and was demonstrated to the authorized nuclear inservice inspector (ANII) and the Region II NRC Inspector.
h.
FPL feels that the extent of examinations conducted and the volume achieved provide assurance of an acceptable level of quality and safety.
5.
Licensee's Proposed Alternative Examinations a.
Conduct examinations to the extent possible during the last outage of the third period to the 1980 Edition through Winter 1981 Addenda of Section XI Requirements.
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System pressure tests as required by Section XI 1980 Edition through Winter 1981 Addenda.
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Staff Evaluation 1 ~
This relief request and the evaluation and conclusions provided herein apply to the first ten-year inservice inspection intervals for Turkey Point Units 3 and 4.
The inspection intervals for Units 3 and 4 ended on February 21 and April 14, 1984, respectively.
Relief from the examination requirements of the 1974 Edition through Summer 1975 Addenda of Section XI for the reactor vessel nozzle-to-safe end and safe end-to-pipe welds had been requested by Florida Power and Light Company (FP8L) near the end of the intervals but was denied by the staff because of insufficient supporting information.
FP8L withdrew the request until access to the reactor vessel nozzles could be gained and detailed information in support of the request could be obtained.
Notifying the Commission of Code requirements determined to be impractical after expiration of the ten-year interval and submitting supporting
~ information are allowed by 10 CFR 50.55a(g)(4)(IV).
The intent 1
of this provision of the regulation is to cover those situations in which the impracticality or the extent of impracticality of a Code requirement could not be foreseen and was not included in the revised inservice inspection
- program, as is the subject case.
The staff has reviewed the information provided by the licensee including the sketches of the nozzle welds showing the various obstructions, the detailed extent of examinations that can be achieved by visual, surface, and ultrasonic techniques, and the extent of examinations performed during the past ten-year interval.
The information presented clearly supports the licensee's deter-mination that the required code surface and volumetric as well as visual examinations were 'impractical to perform completely, pri-marily due to the reactor vessel supports and biological shield
w7w wall interferences with the reactor vessel nozzle-to-safe end and safe end-to-pipe welds.
Based on the sketches showing the extent of examination coverage, coverage of the welds by a combination of visual, manual and mechanized penetrant, and ultrasonic techniques ranges approximately from 85 to 100 percent of lengths of the welds.
The staff has determined that the combination of methods covers a sufficient amount of the required examination surface and volume to conclude that any significant defects in the welds and base material would most likely have been detected during the examination interval.
To impose additional requirements would not significantly increase the probability of flaw detection over that attained by the methods utilized and the extent of coverage achieved in light of the existing obstructions to state-of-the-art examination technology.
Based on this, the staff concludes that relief from achieving 100K of the Code requirements may be granted as requested.
The request to utilize the surface examination requirements of the 1980 Edition of Section XI in lieu of the 1974 Edition for the reactor vessel and steam generator nozzle-to-safe end and safe end-to-pipe welds has also been reviewed by the staff.
The 1974 Edition required surface examination to cover the weld plus one wall thickness beyond the edge of the weld.
This require-ment was intended to cover the weld and heat-affected zone.
However, for relatively thick walled components, the reouirement covers areas of the component material not affected by the welding process.
In recognition of this fact, this requirement was revised in the lat'er editions of Section XI to require surface examination to extend only 4-inch beyond the edge of the weld.
l This distance pr>> ovides sufficient margin to cover the heat-affected
- zone, an area of the material in which flaws are most likely to
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The staff concludes that utilizing the requirements of the later edition of the Code for the surface examination will not decrease the effectiveness of detection of flaws in the heat-affected zone and that use of the later edition of Section XI for the surface examination requirement may be granted.
B.
Relief Request No.
2 1.
Component Identification
- Class 1
- Code Category 8-F
- Pressure Retaining Dissimilar Metal Welds - Reactor Pressure Vessel Safe-Ends
- Code Item Number:
B5.10 2.
Examination Requirements:
(1980 Edition through Winter 1981 Addenda)
The examinations performed during each inspection interval shall cover the circumference of lOOX of the welds.
Nozzle safe-end welds require volumetric and surface examination methods.
The area subject to examination is identified in IMB-2500-8.
3.
Relief Requested Relief is requested from the "code volume and surface area not achievable in the performance of ultrasonic and liquid penetrant examination" for the following welds:
Plant/Unit No.
PP-UL INLET OUTLET INLET OUTLET INLET Meld Identification 9-RCS-1304-1 27.5-RCS-1307-14 29-RCS-1305-1 27.5>>RCS-1306-14 29-RCS-1308-1
- 27. 5-RCS-1309-14 HOT LEG COLD LEG HOT LEG COLD LEG HOT LEG COLD LEr.
PTP-4 OUTLET INLET OUTLET INLET OUTLET INLET 29-RCS-1404-1
?7.5-RCS-1407-14 29-RCS-1405-1 27.5-RCS-1406-14 29-RCS-1408-1
- 27. 5-RCS-1409-14 HOT LEG COLD LEG HOT 'LEG COLO LEG HOT LEG COLO LEG 4.
Licensee's Stated Bases for Requesting Relief a.
Portions of the required volumetric and surface area are inaccessible due to permanent physical obstructions in the annulus area around the reactor pressure vessel, i.e.,
biological shield wall, insulation brackets, nozzle support
- lugs, and sand box area.
b.
In order to conduct these examinations at Turkey Point access to these areas can only be performed from the refueling pool which requires the seal ring and sand plug removal.
c.
Nonremovable vessel insulation restricts access.
d.
Less than 50% of the surface area can be effectively examined.
e.
Performance of these examinations on the nozzles involves excessive cost, man-hours, and man-rem with little or no compensating increase in the level of quality and safety.
f.
FPEL feels that the extent of examinations conducted and the volume achieved provide assurance of an acceptable level of quality and safety.
5.
Licensee's Proposed Alternative Examinations a.
Conduct volumetric and surface examinations to the extent possible for Code category B-F, inlet reactor pressure vessel nozzle safe-end welds.
PTP-3 PTP-4 27.5-RCS-1307-14 27.5-RCS-1306-14
- 27. 5-RCS>>1309-14 27.5-RCS-1407-14 27.5-RCS-1406-14 27.5-RCS-1409-14 b.
Conduct a full volume ultrasonic examination technique to effectively examine the outside surfaces of the reactor vessel. nozzle safe-end welds (outlet nozzles) in lieu of the surface examinations as defined in the proposed Attach-ment No.
2 to this relief request.
PTP-3 PTP-4 29-RCS-1304-1 29-RCS-1305-1 29-RCS-1308>>1 29-RCS-1404-1 29-RCS-l405-1 29-RCS-1408-1 c.
Conduct system pressure tests as required by Turkey Point Inservice Pressure Test Program.
6.
Staff Evaluation This relief request, evaluation, and conclusions apply to the second ten-year inservice inspection intervals for Turkey Point Units 3 and 4 which began on February 22 and April 15,
- 1984, respectively.
The staff has reviewed the information contained in the attach-ments to the letter dated August 6, 1986 which was provided by the licensee to demonstrate the impracticality of the Code requirements for complete examination of the reactor vessel nozzle-to-safe-end and safe-end-to-pipe welds at Turkey Point Units 3 and 4.
The information provided indicates that 100Ã of' the required ultrasonic examination of the welds in the reactor vessel hot legs can be performed from the inside diameter (I.D.) of the pipe, less than 50K of the weld lengths o~ both the hot and cold leqs can be examined by surface, and less than 505 of the lengths of welds in the cold legs can be examined by ultrasonic techniques.
The extent of the examinations is limited by the vessel supports and biological shie1d wall.
The licensee proposes to conduct a volumetric examination (from the I.D. of the pipe) of the welds in the hot legs with an ultrasonic technique capable of detecting outside diameter (O.D.) flaws, thereby eliminating the surface examination requirement.
The welds in the cold legs will be examined to the extent practical by both the ultrasonic technique and surface methods.
The ultrasonic examination technique proposed for the welds in the hot legs has been demonstrated to and witnessed by a Region II inspector.
A detailed description of the technique and the results. of the demonstration are documented in I.E. Report Hos.
50-250/86-15 and 50-251/86-15 dated March 26, 1986.
The demon-strations were performed on a mock-up simulating a 29-inch diameter X 2.750-inch wall reactor vessel nozzle, nozzle cladding, pipe weld, and reactor coolant piping material with I.D. and O.D. axially and circumferentially oriented surface flaws.
The demonstration showed that the ultrasonic technique was capable of detecting surface indications of a size smaller than those allowed by Section XI.
Although there were some differences between the mock-up demonstration and actual application, i.e.,
manual versus automatic
- scans, Ultragell II couplant versus
- water, and standard DAC versus electronically enhanced, the results obtained by the actual examination should not be adversely affected.
The staff has determined that the proposed ultrasonic technique will provide the necessary assurance that significant O.D. flaws will be detected and that the structural integrity of the welds has not been compromised.
Me, therefore, conclude that relief from the surface examination requirement for the hot leg welds may be granted when the proposed ultrasonic examination technique is utilized.
The licensee has stated that examination of the inlet nozzle-to-safe-end welds will be performed by both the proposed ultrasonic technique and surface examination "to the extent practical."
Clarification of "to the extent practical" was requested by the staff via telephone on December 4, 1986.
The licensee's response was that due to the geometry of the elbow-to-nozzle in the cold legs, the total amount of coverage of the welds that would provide acceptable ultrasonic examination results with the new technique was not known at this time and would be known only when the actual examination is performed.
However, attempts to perform the examination on 100K of the required volume would be made-and surface examinations would be performed manuallv on accessible areas of the welds to supplement the volumetric examination.
The examination of the welds in the cold legs can be performed only when the core barrel is removed.
The amount of coverage of the welds by both examination methods is an important consideration in assessing their struc'trual integrity.
Relief from the Code require-ments cannot be granted at this time because of the uncertainty in the extent of weld coverage.
The staff will reconsider the request when the examinations are performed and details of the results are provided.
III. CONCLUSIONS A.
Relief Request No.
12 The conclusions provided for Relief Request No.
12 apply to the first ten-year ISI intervals for Turkey Point Units 3 and 4.
The inspection intervals for Units 3 and 4 ended on February 21 and April 14, 1984, respectively.
Notifying the Commission of Code reouirements determined to be impractical after expiration of the ten-year interval and submitting supporting information are allowed by 10 CFR 50.55a(g)(4}(IV>.
The intent of this provision of the regulation is to cover those situations in which the impracticality or the extent of impracticality of a Code requirement could not be foreseen and was not included in the revised inservice inspeciton
- program, as is the subiect case.
The staff has determined that relief from the inservice examinations required by Section XI is justifiable.
The alternative examinations, as proposed by Florida Power and Light Company, will cover a sufficient amount of the surface and volume and will not decrease the effectiveness of detecting flaws in the heat-affected zones based on the details provided in the evaluation portion of this Safety Evaluation.
Therefore, relief may be granted pursuant to paragraph 10 CFR 50.55a(gl(6)(i) based on our finding that certain specific requirements of the Code are impractical, and the alternative examination imposed will provide an acceptable level of quality and safety.
The granting of this relief is authorized by law and will not endanger life or property or the common defense and security, and is otherwise in the public interest giving due consideration to the burden that could result if the requirements were imposed on the facility.
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B.
Relief Request No.
2 The conclusions provided for Relief Request No.
2 apply to the second ten-year ISI intervals for Turkey Point Units 3 and 4.
These intervals begin on February 2? and April 15, 1984, respectively.
The staff has determined that relief from the surface examination required by Section XI is,iustifiable.
The alternative examinations, as proposed by Florida Power and Light Company, will provide the necessary assurance that significant 0.0. flows will be detected and that the structural integrity of the welds will not be compromised for the hot leg welds based on the details provided in the evaluation portion of this Safety Evaluation.
- However, due to the uncertainty of the extent of coverage utilizing the alternative examinations (ultrasonic technique) for the cold leg welds, relief cannot be granted for these welds based on the details provided in the evaluation portion of this safety evaluation.
This portion of the relief request will be reconsidered at the time information necessary for assessing the extent of coverage of the welds can be obtained.
Therefore, relief may be granted for the hot leg welds pursuant to paragraph 10 CFR 50.55a(g)(6)(i) based on our finding that certain specific requirements of the Code are impractical, and the alternative examination imposed will provide an acceptable level of quality and safety.
The granting of this relief is authorized by law and will not endanger life or property or the common defense and security, and is otherwise in the public interest giving due consideration to the burden that could result if the reauirements were improsed on the facility.
Relief is denied for the cold leg welds for the above stated reasons.
Oated:
February 13I 1987 Principal Contributor:
G. Johnson
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