ML20214P343

Forwards Addl Info Re Inservice Insp Program Plan for Plant, Per 870213 Request.During First Refueling Outage,Five RHR Sys Welds from Exam Category C-F,Item C5.11,received Surface Exam

ML20214P343
Person / Time
Site:	Byron
Issue date:	05/28/1987
From:	Ainger K COMMONWEALTH EDISON CO.
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
References
3115K, TAC-60703, NUDOCS 8706030326
Download: ML20214P343 (7)

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CenNnonwealth Edloon r - - . - One Frat Nabonal Plaza. Chicago. IEnois

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\ Address Reply to: Post Omco Box 767 Chscago, IEncis 60800 - 0767 May 28, 1987 U.S. Nuclear Regulatory Comunission Attn: Document Control Desk Washington, DC 20555

Subject:

Byron Station Unit 1 Inservice Inspection Program TAC No. 60703

- NRC Docket No. 50-454

Reference:

(a) February 13, 1987 letter from L.N. Olshan to D.L. Parrar 4

i Gentlemen:

Reference (a) transmitted a request for additional information concerning the Inservice Inspection Program Plan for Byron Station Unit 1.

l Enclosed is the additional information-requested in reference (a).

Please direct any questions regarding this matter to this office.

( Very truly yours, L C .

i K. A. Ainger Nuclear Licensing Administrator Enclosure I

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! cc: Byron Resident Inspector NRC Region III Office l' ,

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ENCLOSURE Response to Request for Additional Information Byron Station Unit 1 Inservice Inspection Program Plan ISI Program Plan - Section 2.2 A. Review of ISI Program Tables for Class 2 welds in the Main Steam (MS)

System (Pages 326 through 340 of 407) show that, of the 145 Class 2 welds listed as Examination Category C-F, Item C5.21, only 30 welds (21%) are identified for ISI examination during the first 10-year interval. Based on the code requirement of 25%, it appears that six additional welds should be selected for examination in order to meet the Code requirement.

As the above finding was part of a sampling, the Licensee should review other systems as well as the Main Steam System to verify that the Code requirements are being met with respect to the number of welds being selected for examination during the first 10-year interval.

Response: Of the 145 class 2 welds listed as Examination Category C-F, Item C5.21, 97 are greater than 8 inch nominal pipe size and 48 are less than or equal to 8 inch nominal pipe size. Per Notes (1)(d)(3) and (4) of Examination Category C-F, additional welds selected shall equal 10% of circumferential piping welds less than or equal to 8 inch NPS (5 of 48 selected) and 25% of circumferential piping welds greater than 8 inch NPS (25 of 97 selected). Therefore, the 30 welds selected meet Category C-F, Item C5.21 requirements when pipe size is considered.

Prior to submittal of the ISI Program Plan, and subsequent revisions which affect the number of welds in piping systems, the percentage of welds selected within each system and Code item number are verified to meet Section XI selection

! requirements.

I ISI Program Plan - Sections 2.2 and 2.4 B. Staff review of the ISI Program Plan for Class 2 pressure retaining welds in the Residual Heat Removal (RHR) System shows that, of the 228 I Examination Category C-F welds listed in the Program Tables (Section 2.2),

20 welds are scheduled to receive surface examinations and 1 is listed for a volumetric examination during the first 10-year interval. Although this constitutes an acceptable sample, the Licensee should perform volumetric examination in lieu of the scheduled surface examination for these welds.

Response: During the first refueling outage, five (5) Residual Heat Removal (RH) system welds from Examination Category C-F, Item C5.11, received a surface (PT) examination. Byron Station will concur with the staff position and, during subsequent refueling outages, volumetrically examine the twenty one (21) Examination Category C-F, Item C5.11, RH system welds. The already completed surface examinations will be taken credit for, but not repeated during subsequent intervals.

(1)

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Staff rsview of tha ISI Program Plan alto a: hows that the Containm:nt Spray "C.

System has been completely exempted from ISI examinations based on the pressure / temperature exemption criteria contained in IWC-1220(b). This system should not be completely exempted from inservice volumetric examination based on Section XI exclusion criteria contained in IWC-1220.

For similar plants, the staff has previously determined that a 7.5%

i augmented volumetric sample of the Class 2 welds from the Containment Spray Pumps to.the.first weld beyond the isolation valve inside j~ containment constitutes an acceptable resolution. The staff points out that later editions and addenda of the Ccde do not permit the temperature / pressure exclusion for RHR, ECC, and CHR Systems.

Response: It is Byron Station's understanding that the underlying staff I concern, and primary reason for not exempting the containment spray system, is the presence of stagnate borated water in stainless steel piping systems. This problem was originally i identified in IE circular 76-06 and further in IE Bulletin 79-17, " Pipe Cracks in Stagnate Borated Water Systems at PWR Plants". Byron station's position is that Bulletin 79-17, and therefore the requested 7.5% augmented sample, does not apply to Byron for the following reasons:

l 1) The operating boron concentration of the reactor coolant r

and support systems is a maximum of 4% boron at Byron.

2) Byron has established chemistry control programs in accordance with Technical Specifications to maintain low j dissolved oxygen content (<0.10 ppm) and low chloride /flouride content-(< 0.15 ppm). Further, outside agents contacting the piping (inside and outside) must be less than 0.10 ppm chloride /flouride content.

3) Per the piping system design specification, ASME Class piping systems are constructed with a minimum of schedule 40 pipe.

4) Commonwealth Edison's Zion Station is a similar plant, with respect to piping configuration, to Byron. Non-destructive j examination (NDE) of stagnate borated piping systems in 1976, 1977, and 1979 revealed no reportable indications or pipe wall degradation.

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5) The Byron ISI Program Plan calls for volumetric inspection

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of 49 welds (including 21 RH welds referenced in "B" response) contained in the RH and Safety Injection (SI) systems. These welds are included in 8", 10", 12", 16",

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and 24" lines which remain statically flooded during normal plant operation. For the above stated reasons, Byron Station does not consider a 7.5% augmented sample of CS welds necessary at this time. However, the augmented sample will be considered if volumetric examination results 1 of the RH and SI systems warrant concern and an additional sample selection.

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ISI Program Plan - Srction 2.3 D. Notes 2 and 3: Notes 2 and 3 discuss Code Class 1 and Class 2 pressure retaining piping welds selected for examination during the first inspection interval which have geometric configurations which limit the ultrasonic examinations for reflectors parallel to the weld. The Notes state that the inspection covers essentially 100% of the required weld i volume. However, the Code does not define the term " essentially 100%."

The staff should be provided with an accurate estimate of the percentage of the code-required volumetric examination that can and will be completed for each item listed in Notes 2 and 3. If the subject welds are not receiving 100% of the Code-required volumetric examination, relief should.

be requested.

Response: It is Commonwealth Edison's position that where the code states

" essentially 100% of weld length" (i.e, Note 3 of Examination

< Category B-J), this shall be interpreted as no less than 90% of the total weld length. The Code is vague i and open to interpretation in this critical area. The NRC Staff-has approved this position for use at Zion Nuclear Power Station in a letter from S. A. Varga (NRC) to D.L. Farrar (Ceco) dated February 11, 1986.

Note 6: Note 6 in the ISI Program Plan states that, since the exposed E.

surface of the Reactor Coolant Pump flywheels is coated with a corrosion preventative primer paint, a surface examination of these surfaces each.

10-year interval is not practical. If this is the case for liquid penetrant surface examination, has the Licensee considered using a magnetic particle surface examination? Also, Regulatory Guide 1.14, Paragraph C.4.b(2) requiras "a surface examination of all exposed surfaces

! and a complete ultrasonic volumetric examination at approximately 10-year intervals,' during the plant shutdown coinciding with the inservice inspection schedule as required by Section XI of the ASME Code." Verify that the complete ultrasonic volumetric examination will be completed during the 10-year interval.

Response: Each reactor coolant pump flywheel will be subjected to a complete ultrasonic volumetric examination each 40 month period during refueling or maintenance shutdowns coinciding with the service inspection schedule as required by Section XI of the ASME Code. In addition, a surface (MT) examination of all exposed surfaces, and a surface (PT) examination of the bore and keyway, will be performed whenever the flywheels are removed for maintenance purposes, but not more frequently than once each 10 year interval. The performance of the above examinations meets and exceeds the Byron Technical Specification 3/4.4.10,

" Structural Integrity", surveillance requirements as well as the requirements of Regulatory Guide 1.14. Note 6 will be revised to more clearly represent this position.

(3) 1 4

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'2 -* F1 Noto 7h Note 7 ditcu sss Augmentsd InJpection of ths Turbina Rotors cnd states that:. "At'this time the inspection frequency for subsequent

v. examinations...(following the first refueling outage)... is being evaluated and shall be submitted at a later date." Indicate when this

information will be available for staff review.

I i l . Response: Westinghouse generic turbine rotor integrity methodology l provides a procedure for estimating crack growth, missile generation probability, and volumetric inspection intervals.

This methodology is being used on the low pressure turbine rotors of Byron Unit I to determine new inspection intervals

?f based on the existence or lack of flaws observed during the l

inspection. Refer to a May 20, 1985 letter from B. J.

Youngblood (NRC) to D. L. Farrar (Ceco.).

G. Note 8: Examination Category C-C requires a surface examination of integrally welded attachments as defined by Figure IWC-2500-5. The two

, , integrally welded attachments, as identified in Note 8, to which the connecting component support has been deleted, should not be considered to be' exempt from the above requirement. Even though the additional static f,

l or dynamic loads of the connecting component support have been removed,

[ the integral attachment weld still exists on the piping pressure

[., boundary. If the Code-required examination can not be completed, a request for relief is required.

Response: ASME Code Interpretation XI-80-03, which references Examination Category C-E-1 of 1974 Edition - Summer 75 Addenda, states that integrally welded attachments which are not used for support or restraint of components are not subject to examination requirements. Although later editions of Section XI changed the Category from C-E-1 to C-C, the examination requirements remain unchanged, as well as the intent of the code Interpretation.

i Therefore, Byron Station maintains that the two integrally l

welded attachments identified in Note 8, to which the connecting component support has been deleted, are exempt from Examination

) Category C-C requirements. These welds will, however, be f included in the Visual VT-2 Examination requirements of Examination Category C-H.

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1 ISI Program Plan - Section 2.7 l-

! II. Relief Requests NR-4, NR-5, NR-6, and NR-7: The February 6, 1986 cover

' letter for the ISI Program Plan submittal states that these relief requests have been omitted from Section 2.7 of the ISI Program Plan as these relief requests address the volumetric examinations of various cast stainless steel welds in the reactor coolant loops and that they will be submitted for staff review later. Indicate when this information will be made available for staff review. Review of the ISI Program Plan cannot be completed until all relief requests for the first 10-year inspection interval have been received and reviewed. ,

Response

Relief Requests NR-4, NR-5, NR-6, and NR-7 will be finalized

,9 A following completion.of the scheduled cast stainless steel loop weld examinations during the first refueling outage. The subject relief requests will then be submitted to the staff l

prior to-September 1, 1987 for their review.

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• I.. Reli*f R*cuert NR-8: Tha ASME Siction XI Requirements as listed in R311sf Request NR-8 are Examination Categories B-L-1, B-M-1, B-L-2, and B-M-2.

The only items listed in the' relief request are Reactor Coolant Pump casing internal surfaces which are Examination Category B-L-2, Item No.

4 B12'. 20. The references to the other Examination Categories should be.

deleted from-this relief request as they are not applicable.

Response: The reference to B-L-1, B-M-1, and B-M-2 will be deleted from NR-8.

J. Relief Request NR-9: The ASME Section XI Requirements as listed in Relief Request NR-9 are Examination Categories B-L-1, B-M-1, B-L-2, and B-M-2.

The only items listed in-the relief request are valve body internal surfaces which are Examination Category B-M-2, Item No. B12.50.. The references ~to the other Examination Categories should be deleted from this relief request as they are not applicable.

Response: The references to B-L-1, B-M-1, and B-L-2 will be deleted from NR-9.

K. Relief Request NR-15: In Relief Request NR-15 confusion exists as to the weld for which relief is required. The text for the relief request lists Weld Number C-1 as a valve-to-pipe weld (Examination Category C-F).

Inconsistencies exist between the relief request text and the Attachment 1

. table and drawing. The drawing shows the valve-to-pipe weld to be Weld No. C-2A (FW398) and the table lists Weld C-2A (FW398) as a Pipe-to-Valve Containment Assembly Weld. Likewise, Weld C-1 (PW368) is shown on the drawing as a pipe-to-valve' containment assembly weld and in the table it

] is listed as the valve-to-Pipe Weld. Provide clarification as to the weld and Examination Category for which relief is requested.

4 Response: The identification of field welds FW368 and FW398 on the drawing portion of Attachment 1 was inadvertently switched. The welds as identified in the table of Attachment 2 are correct.

Relief is requested from the examination requirements of Examination Category C-F, Item C5.21 and Examination Category C-H, Item C7.30 for valve-to-pipe welds C-1 (FW368) and.C-1 (PW372). The reference to performance of the visual examination -

4 (VT-2) will be deleted from the " Alternate Test Method" as this test is also impractical.  ;

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i. IS.I Program Plan - Sections 5.4 and 6.4 L. Relief Request CR-2: CR-2 requests relief from the examination boundaries as defined by the Code for all non-exempt component supports on insulated lines, The IWF boundary of an integral attachment to the pressure retaining component begins where the IWB, IWC, or IWD boundary ends.

Provide an estimate of the total number of supports, by Code class, which are not covered by the definition described in IWF-1300(e).

Response: The following numbers are estimates of total number of non-exempt insulated line supports by class.

250 Non-exempt Class 1 supports on insulated lines.

150 Non-exempt Class 2 supports on insulated lines.

O Non-exempt Class 3 supports on insulated lines.

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IWF-1300(e) covers approximately 20 percent of these supports further reducing the class 1 and Class 2 non-exempt support numbers to 200 and 120 respectively.

Finally, some of the insulation on these pipes may stop at the pipe support clamp and start again on the other side of the pipe clamp. This will reduce the total numbers again by about ten percent leaving the following conservative estimate of the number of supports for which relief is requested:

180- Class 1 supports not covered by IWF-1300(e) 110 Class 2 supports not covered by IWF-1300(e)

O Class 3 supports not covered by IWF-1300(e)

M. Relief Request SR-1: SR-1 requests relief from the examination boundaries as defined by the Code for-non-exempt safety-related snubbers covered by insulation. The " Justification" states that in some cases, the mechanical connection of a non-integral attachment is buried within the component insulation. This relief request also indicates that there are approximately 429 non-exempt safety-related snubbers on insulated components. Are all of the 429 snubbers buried within the component insulation? If not, provide an estimate of the total number of snubber attachments for which relief is being requested.

Response: With respect to non-exempt safety related snubbers on insulated components, essentially all (greater than 90%) of the snubber pipe clamps can be assumed to be covered by insulation. None of the snubbers are buried in the insulation. Approximately ten Pacific Scientific ' SE r 1/4 or PSA 1/2 Class ~ 1 snubbers are partially covered by insulation due to their small size relative to thick.(3" radius) insulation. The insulation, however, does not interfere with snubber operation.

General N. Verify that there are no additional requests for relief other than those .

received in Sections 2.7, 5.4, and 6.4 of the ISI Program Plan received February 6, 1986 and NR-4, NR-5, NR-6 and NR-7 regarding the volumetric j- examinations of various' cast stainless steel welds in the Reactor Coolant

System. Indicate when NR-4 through NR-7, and any additional relief requests, if required, will be received for staff review.

Response: Per the response to item (H), relief requests NR-4 thru NR-7 will be submitted prior to September 1, 1987. At this time, no additional relief requests are known to be required for the ISI Program Plan.

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