ML20205C616
| ML20205C616 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 03/20/1987 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20205C539 | List: |
| References | |
| NUDOCS 8703300222 | |
| Download: ML20205C616 (8) | |
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UNITED STATES
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- J l' j NUCLEAR REGULATORY COMMISSION
- E WASHINGTON, D. C. 20555 o
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SAFETY EVAltfATICN BY THE OFFICF OF NIffl. EAR REACT 0P PEGULATION RELATIts TO RELIEF FPOM CERTAIN FE0VIREMENTS OF SECTION XI 0F THE ASME CODE METPOPOLITAN EDISOP COMPANY JEPSEY CENTRAL POWER AND LIGHT COMPANY PENNSYLVANIA ELECTRIC COMPANY GPU NUCLEAR COPPCRATION THREE Mile ISLAND NUCLEAR STATION, UNIT N0. 1 DOCKET NO. 50-789
1.0 INTRODUCTION
The Technical Specifications for the Three Mile Islend Unit 1 (TMI-11 require that inservice examination of ASME Code Class 1, 2 and 3 components shall be performed in accordance with Section XI of the ASME Code as required by 10 CFP 50.5Ea(g)(4) except where specific written relief has been granted by the Commission. Because some plants were designed in conformance to early editions of this Code Section, certain requirements of later editions and addenda of Section XI are impracti-cal to perform due to the plants' design, component geometry, and material of construction. Consequently, paragraph 10 CFP 50.55a(g)(6)(i) authorizes the Commission to orant relief from those requirements upon making the necessary findings.
In letters dated August 20, 1986 and October 20, 1986, the GPU Nuclear Corporation (GPU or the licensee), identified specific ASME Code reouirements that GPU determined to be impractical to perform at TMI-1 and reauested relief from these requirements. The NRC staff evaluated the licensee's supporting technical justification and found the requested relief to be acceptable except for relief requests Nos. 4 and 7, where respectively, relief was withdrawn and the information was not sufficient to make a determination.
The current TMI-1 Inservice Inspection (ISI) Program is based on the ASME Code,Section XI,1974 Edition including Addenda through Summer 1075.
Additionally, GPU has adopted certain portions of ASME Section XI, 1977 Edition, including Addenda through Summer 1978 (specifically, IWA-??00, IWA-?300, and IWA-3000) as described in their letter dated July 6, 10Pl.
?.0 EVflUATION The licensee requested relief from specific ISI requirements and provided supporting technical information. We have reviewed this infonnation as related to the design, geometry, and materials of construction of the components. Each relief request is characterized below with a summary of the NRC staff's evaluation.
8703300222 870320 DR ADOCK 05000289 PDR
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A.
Relief Peouest fo. 1, Examination rategory B-B. Item No. P3.1.
Letdwn Cooler Panifold longitudinal Seam Weld.
Cede Fecuirement: Section XI, Tables Ik'R-?500 and IKE-?600, reenire a volumetric examination durina each inspection interval of at least 10f of the length of each longitudinal shell weld.
Code Relief Recuest:
Relief is reauested froni cerformine the volumetric examir:ation of the entire 10% o# the length of each lonoitudinal seam weld.
Reason for Recuest: The letdcen coolers (Mlt-CIA /B) are of a helical coil design whose function is to cool reactor coolant water prior to entrance into the makeup and purificetion demineralizers.
The welds involved are located on the inlet and outlet manifolds identified as assemblies PAI and PA? on drawing NU-D-1002 that has been provided to the NRC staff. Each manifold contains one continuous weld for the full length of the manifold, but for ISI documentation and location purposes, each manifold is considered to have two welds each. These manifolds are approximately 31" lono end are an integral part of the heat exchanger. Only approximately 1-1/4" of the inlet and ?-3/4" of the outlet welds are accessible for examination.Section XI of the Code requires 10t or 3.1" of these welds to be volumetrically examined each interval but, in this case. less than 3.1" of the welds are accessible.
The licensee intends to replace both coolers during the current 6P Outage. A pre-service examination will be performed on the accessible portions of these welds in both coolers prior to installation. Also, prior to the expiration of the present interval, inservice examination will he performed on the accessible portion of a percentace of the total number of these welds as required by the Code.
The coolers are located in the letdown cooler room in the reactor building basement where previous plant history indicates radiation fields of about 100 mr/hr general area with hot spots in excess of IR/hr. Also, it is anticipated that radiation fields will increase significantly as plant operation continues.
The areas to be examined intersect the circumferential piping tie-in welds and are the most highly stressed area of the manifold.
It would be expected that any failures in the manifold would originate from this area and would be detected during examination.
Failures in the inaccessible pertion of the manifold car be detected at an early stage and isolated on noting an increase in the volume and radioactivity of the intermediate closed cooling system which is the heat sink for the coolers. System hydrostatic and leak tests will t'e performed on these coolers in accordance with ASME Section XI.
Therefure, the licensee believes that eranination of the accessible portion of these welds in accordance with the Code required frequencies is adeouate and meets the intent of the ASME Code.
Staff Evaluation and
Conclusion:
Based on the review of the drawino provided by the licensee, we have determined that a volumetric examination to the extent specified by the Code is impractical for the entire inspection interval. The licensee intends to replace buth heat exchangers and perform a pre-service examination.
In addition, the licensee intends to per#orm a volumetric examination er the accessible portion of these welds as required by the Code prior to the expiration of the present interval.
The Code required examinations for this Examination Cateoory are based on the inservice inspection of a representative sample of welds to detect generic service-induced decradation if present. At least for the outlet welds, the licensee could perform essentially 100% of the Code requirement for the entire interval. The samplino tFat can be performed on both the outlet and inlet manifold is in the most highly stressed area.
Since the licensee intends to replace the heat exchangers during the current cutace and perform an inservice inspection o' the accessible portions of the weld, we conclude that this plan is acceptable for the balance of this inspection interval.
B.
Relief Pequest No. ?, Examination Category C-G, Item C4.1, ASMF Class ?, Valve Body Welds On Valves AH-VIA, AH-VIP, AH-V1C, and AH-VID.
Code Pequirement:
ASPE Section XI,1974 Edition, including Addenda through Summer 1975, requires a volumetric examination of pressure retaining valve body welds.
Code Relief Peouest: The licensee intends to adopt the recuirements of ASME Section XI, 1977 Edition, including Addenda through Summer 1978, Table IWC-2500-1, Examination Category C-G, Item No. C6.20, for the performance of inservice inspection on the subject reactor building purge valves.
Peason for Request: The licensee is advising the NRC of its intent to use portions of later Code editions referenced in 10 CFR 50.55 afb).
Therefore, relief from ASME Code requirements is not needed for this item. GPU intends to perform a surface examination of the welds in these valves as required by this updated portion of the Code.
Staff Evaluation and
Conclusion:
Paragraph 10 CFR 50.55a(g)(4)(iv) states:
... listed in paragraph (b) of this section, and subject to Commission approval. Portions of editions or addenda may be used provided that all related requirements of the respective editions or addenda are met."
The licensee intends to use provisions from a later approved ASMF Code edition and addenda. Even though the extent and method of examinations have been reduced, other licensees with ISI programs
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based en the later ASPE Code documents are followino these requirements pursuant to 10 CFP E0.55a(c)(4). The staff has reviewed the licensee's request and has determined that the licersee proposes to use all related reouirements of the proposed Code edition. The staff finds the request relief acceptable.
C.
Relief Request No. 3, Examination Categorv B-I-1 and B-I-2, Vessel Clad Patches, Items B1.13, Bl.14, PP.9, and P3.8 Code Requirement: ASME Section XI,1974 Edition, including Addenda through Summer 1975, requires a visual examination of at least one patch (36 souare inch) in the primary side of the vessel.
Code Relief Request: The licensee requests relief to eliminate the requirement to examine the clad patches on the reactor vessel.
Reason fur Peouest: The examination of vessel cladding patches requires examination personnel to enter high radiation areas, resulting in substantive radiation exposure. Based on radiation levels obtained during the 1979 TMI-1 refueling outage. personnel would be enterino radiation fields from 3 to 5 R/hr.
It is estimated that this examination would expend 1.5 - 3.0 person-rem.
To date, four 36 sq. in, patches have been surface and visually examined in the reactor vessel head and four 36 'sq. in, patches have been visually examined in the reactor vessel. These examinations revealed no degradation, which is consistent with other B&W plants of similar design, and provide a basis for assuring the structural integrity of the cladding.
Further examinations would provide minimal information to be gained for the amount of radiation expenditure involved.
Later referenced editions of ASME Section XI (1977 with Addenda through Summer 1978) do not reauire claddino examinations.
Staff Evaluation and
Conclusion:
The licensee proposes to use provisions from a later approved ASME Code edition and addenda.
The staff has reviewed the licensee's request and has determined that the licensee proposes to use all related requiremerts of the proposed Code edition. The staff finds the request relief acceptable.
D.
Relief Request No. 4, Examination Category B-F, F eactor Vessel Core Flood Safe-End Welds, Iten Bl.6 Code Reouirement: ASME Section XI, 1974 Edition, includino Addenda through Summer 1975, requires a volumetric and surface examination of these welds.
Code Pelief Request: The licensee originally requested relief to eliminate the surface examination reoufrerent.
-E-Feason for Pequest: The examinations involved in this request for relief are currently scheduled to be performed durino the 1990 to 1991 time frare. GPU intends to qualify the adecuacy of this ultrasonic examiration technioue to detect unacceptable flaws at both the ID and 00 surfaces prinr tn use.
Due to constant improve-ments in ultrasonic ecuipment and techniques, and the anticipated release of Section XI procedure qualification cuidelines, GPU feels definition of specific ovalification guidelines at a later date (approximately one year prior to examination) may be more appro-priate. The results of this techniove c.ualification will be made available for NRC review. Therefore, this relief request is being withdrawn for administrative purposes at this time. However, we may refer to this request in later correspondence.
Staff Evaluation and
Conclusion:
Since the licensee has withdrawn this request for administrative purposes, no NRC staff action is reouired at this time.
E.
Relief Request No. 5, Examination Category B-M-1, PC-RV2 Valve Body to Flance and Valve Body to Operator Welds, item P6.6 Code Requirement: ASME Section XI, 197d Edition, includina Addenda through Summer 1975, requires a volumetric examination of these welds.
Code Relief Request: The licensee intends to adopt the requirements of ASME Section XI,1983 Edition, Table IWB-2500-1, Examination Cateoory B-M-1, for the performance of inservice inspection on the valve RC-RV?.
Reason for Request: Valve RC-RV? is a ?i" nominal diameter pilot The valve operated relief valve for the reactor coolant system.
is of a design that meaningful volumetric examination results cannot be obtained as shown in a drawing that has been provided to the NRC staff. The valve does not have sufficient area to apply angle beam ultrasonic transducers for scanning. Radiography of the i'
areas of interest cannot be made without inclusion of unfaverable images from other parts of the valve. The licensee intends to perform surface examination of the welds as required by ASPE Section XI, 1983 Edition. Therefore, relief from ASME Code requirements is not needed for this item.
Staff Evaluation and
Conclusion:
The licensee proposes to use The staff has provisions from a later approved ASME Code edition.
reviewed the licensee's request and has determined that the licensee proposes to use all related requirements of the proposed Code edition. The staff finds the reouest relief acceptable.
F.
Relief Pequest No. 6, Examination Categories B-H and B-V-1, Intearally Welded Support Attachments, Items B1.17, 67.8, B3.7, P4.9, and 86.4 i
4 Code Requirement: ASME Section XI, 1974 Edition, including Addenda through Summer 1975, recuires a volumetric examination of these welds.
Code Relief Peouest: The licensee intends to adopt the requirements of ASME Section XI, 1977 Edition, includina Addenda throuch Summer 1978, for these welded attachments.
1 Peason for Request: The expected service failure mode for integrally welded support attachments would involve an outside surface flaw. The configuration of tFese attachments is seldoni simple as indicated by a drawing of a typical example that has been provided to the NPC staff. The results of volumetric examina-tien would be less sensitive to the detection of surface flaws than a surface examination method, particularly where the configuration of the welded attachment is more complex and accessi-bility is a problem. The licensee intends to perform a surface examination of the integrally welded attachments equal to or creater than 5/8 inch in thickness as required by the later referenced Code. Therefore, relief from ASME Code requirements is not needed for this item.
Staff Evaluation and
Conclusion:
The licensee proposes to use provisions from a later approved ASME Code edition. The staff has reviewed the licensee's request and has determined that the licensee proposes to use all related requirements of the proposed Code edition.
The staff finds the request relief acceptable.
G.
Relief Request No. 7, Examination Categories C-F and C-G, ASME Code Class ?, Pipe Branch Connection Welds, Item CP.3 Code Requirement: ASME Section XI, 1974 Edition, including Addenda through Sunner 1975, reouires a volumetric examination of these welds.
Code Relief Request: The licensee requests relief to perform a surface examination on 76 main steam system welds and 4 decay heat removal system welds, all of which are ASME Class ? non-exenpt.
Reason for Reouest:
The subject welds are of the standard " weld-o-let" design, or as in the case of some main steam welds, they are of weld-o-let desion with an adjacent reinforcinq pad as shown in a figure provided to the NRC staff. The design of this joint is such that ultrasonic examination from the branch side of the connection cannot be performed due to lack of space required to apply the transducer and due to a constantly changing contour.
Ultrasonic examination from the outside surface of the main pipe run would not be in the correct direction to detect service induced inside diameter flaws and would be less sensitive to outside dia-meter flaws than surface examination techniques. Also, in the case of welds with reinforcing pads, sound would be prevented from penetrating the required volume.
Padiographic examination of these welds is best performed with access to the inside of the piping. Put in this case, without access, less than optimum examination results would be obtained.
Surface examination only of these welds meets later editions of the Section XI Code (Summer 197E and later) and Code Case N-408.
Therefore, the licensee believes that the alternate examinatino is justified and meets the intent of the ASMF Code.
Staff Evaluation and
Conclusion:
We do net have sufficient information to complete an evaluation of this issue. The licensee states that some of the welds contain reinforcement pads.
Generally, this type of structural reinforcement makes inservice volumetric examination impractical.
In order for us to complete an evaluation, the licensee should identify the specific welds with reinforcement pads and provide a table defining the nominal diameter of the main pipe run, the nominal diameter of the branch run, the pipe schedules and material of construction o# the weld-o-let.
H.
Relief Request No. 8, ASME Code Class 1, inteorally Welded Attachments Code Requirement: ASME Section XI, 1974 Edition, including Addenda through Summer 1975, contains requirements for integrally welded attachments that define the areas subject to examination, the extent and frequency of examination and the method of examinatior.,
Code Relief Recuest: The licensee intends to adopt the requirements of ASME 5ection XI, 1980 Edition, including Addenda through 1080, to define the examination boundaries for integrslly welded attachmerts.
Reason for Request: The updated ASME Code was revised to include figures that show that if the attachment weld distance from the pressure boundary is greater than the pressure boundary thickness, it is not in the IVP-boundary.Section XI, 1974 Edition, with Addenda through Summer 1975, does not address this confiouration. Therefore, it is the position of GPU that the 1980 Edition of Section XI con-tained a clarification to examination of welded attachements and this clarification was the intent of the Section XI,1974 Edition, with Addenda through Summer 1975.
Staff Evaluation and
Conclusion:
The licensee proposes to use provisions from a later approved ASME Code edition, e.g. Figures IKB-2500-13. -14, and -15, to define the areas subject to examination. The staff has reviewed the licensee's request and has determined that the licensee proposes to use all related reouirements of the proposed Code edition. The staff finds the request relief acceptable.
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2.0 CONCLUSION
We have completed the review of the licensee's letters dated August 20, 1986 and October 20, 1986 based on the provisions of 10 CFR 50.55a(g)(6)(i).
With the exception of relief requests Nos. 4 and 7, where respectively, relief was withdrawn and the information was not sufficient to make a determination, we have determined that the relief requests are authorized by law and will not endanger life or property or the common defense and security and are otherwise in the public interest giving due consideration to the burden that would result if the requirements were imposed on TMI-1. We, therefore, find that the relief requests should be granted.
As a reminder, GPU should be aware that the regulation permits a licensee to update the ISI Program to meet requirements of certain later ASME Section XI editions, or portions thereof, subject to Commission approval.
In which case, the licensee should notify NRR or the regional office, prior to its implementation, of the scope of all proposed program revisions that modify or affect the ASME Code requirements defined in the regulation and Technical Specifications. We will review and approve actual plant-specific revisions to the ISI Program before implementation.
As such, GPU letter dated July 6,1981 is currently undergoing staff review.
Principal Contributor:
M. Hum Dated: March 20, 1987 i
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