ML040290388

Meeting Handouts - Enclosure 2 - Joseph M. Farley Plant Reactor Vessel Head Penetration Nozzle Inspection Relaxation Unit 2 Spring 2004- 2R16

ML040290388
Person / Time
Site:	Farley
Issue date:	01/29/2004
From:	Southern Nuclear Operating Co
To:	Office of Nuclear Reactor Regulation
Peters S, NRR/DLPM, 415-1842
References
EA-03-009, TAC MC1519
Download: ML040290388 (16)

Text

Joseph M. Farley Nuclear Plant 0 0

Reactor Vessel Head Penetration w Nozzle Inspection Relaxation Unit 2 Spring 2004 -2R16 Mike Stinson Vice President Southern Nuclear 1

Agenda

1. Introduction and Purpose

2. NRC Order EA-03-009 Overview.

Safety Issues

- Inspection Requirements

3. SNC Response to Order

4. Specific FNP 2R1 6 Relaxation Request

5. Basis for FNP 2R16 Relaxation Request

6. FNP 2R16 Spring 2004 Inspection Plans

7. Summary

8. NRC Feedback 2

1. Introduction and Purpose

• Discuss NRC Order requirements

• Discuss Farley's reactor vessel head inspection history and results

• Discuss specific relaxation request for 2R1 6, basis for request, and inspection plans

• Receive NRC feedback on relaxation request 3

2. NRC Order EA-03-009

• Safety Issues

- Corrosion of the RPV head

- Nozzle ejection

• FNP Unit 2 is in the "High" category for susceptibility to PWSCC

• Inspection Requirements - each outage

- RPV head bare metal visual

- Penetration nozzle non-visual NDE 4

3. SNC Response to Order

• SNC consented to the Order

• SNC also requested relaxation of the required inspection coverage due to the physical limits imposed by:

- "Footprint" of the CRDM shroud on the head

- Configuration of the nozzle bottoms (OD thread and ID taper)

• NRC approved the requested relaxation

• An Order revision reflecting these generically applicable relaxations is expected soon 5

4. Specific U2R16 Relaxation Request

• Farley will perform IV. C.(1)(a), bare metal visual of the RPV head

• Relaxation is requested to not perform non-visual examination per Item IV.C.(1)(b)

• Relaxation is requested per Order Item IV.F.(2) because compliance would result in hardship without a compensating increase in safety

• The hardship entailed is an estimated 4.1 Rem of additional radiation exposure to inspection personnel 6

5. Basis for Relaxation Request

• Cracks through either the nozzle or J-groove weld can cause corrosion only after they reach the nozzle annulus area.

• Corrosion products occupy more volume than the steel corroded and therefore are forced to the head surface.

• Bare metal visual inspection will detect corrosion products on the head surface.

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5. Basis for Relaxation Request (continued)

• Fall 2002 2R1 5 bare metal visual inspection of the head and UT exam of the nozzles detected no evidence of cracks.

• Analysis demonstrates that nozzle cracks propagating from below the examined volume (or from flaws within the examined volume too small to detect) would take >2 operating cycles to cause leakage.

• Industry experience shows that leakage over multiple operating cycles is required for head corrosion to threaten a LOCA.

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5. Basis for Relaxation Request (continued)

• Unit 2 head replacement is planned for fall 2005 at 2R17.

• Analysis demonstrates that about 12 cycles of operation are needed for a circumferential crack to threaten nozzle ejection.

• Only 2 cycles will have elapsed since the last nozzle UT in fall 2002 (2R15) when the planned head replacement occurs in fall 2005 (2R1 7)

5. Basis for Relaxation Request (continued)

Unit 2 has injected zinc into the RCS for

>5 years; SNC believes this has mitigated initiation of PWSCC (as has been shown by laboratory testing).

• Unit 2 will have accrued fewer EDY at 2R1 6 (16.8 EDY) than Unit 1 had when found crack-free by BMV and UT examination per the Order in spring 2003 at 1R1 8 (17.5 EDY).

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5 Basis for Relaxation Request U

Summary

• Bare metal visual will address the RPV head corrosion safety concern

- corrosion products will appear on the RPV head

- industry experience demonstrates multiple operating cycles are required to threaten a LOCA

• Analysis shows NDE each outage is not needed to address nozzle ejection safety concern

- circumferential cracking requires about 12 cycles to threaten nozzle ejection 11

6. Farley Unit 2 Spring 2004 Inspection Plans

• Farley will perform a bare metal visual inspection of the outer surface of the RPV top head per Order Item IV. Ca(1)(a).

• Absent approval of the requested relaxation of the Order, Farley will perform UT examination of the RPV penetration nozzles per option IV.C.(1 )(b)(i).

• Farley will also perform a visual examination of the outer surface of the RPV bottom head. as. described in SNC's response to NRC Bulletin 2003-02. 12

7. Summary

• Performing only a bare metal visual inspection provides adequate assurance that the safety concerns of Order EA-03-009 are met.

• This is supported by the previous crack-free inspection history and crack propagation time analyses for FNP Unit 2.

• Performance of non-visual NDE during the spring 2004 Unit 2 outage (2R1 6) would therefore impose a hardship (4.1 Rem dose to inspection personnel) without a compensating increase in the level of quality and safety.

8. NRC Feedback

• SNC's Technical Approach

• NRC's Review Schedule

• Projected Decision Date (2R1 6 Outage Starts 3/13/2004) 14

4' Dia. Penotraflon Nozzle Minimum

\ Interference Fit Zone J-Groove Weld I Minimum Cladding O.D. Thread Approx Lower Limit of UT Coverwage I.D. Taper

• .8;; Penetration nozzle volume I'j W covered by UT exam during L.  ; fall 2002 outage 2R15 NOT TO SCALE FNP UNIT 2 TYPICAL PENETRATION NOZZLE CROSS-SECTION

NRC Bulletins Issued NRC Order 2002-01 EA-03-009 200 1-01 2002-02 Issued 2R14 1R17 21 U15 lR18 2R16 1R19 2R17 Al I I l I I _-

l 1l 1 - 1S1 1S6 S I-n I _

2001 2002 .2003 2004 2005 2006 Performed Unit 2 Performed Unit 2 Relaxation Planned Unit 2 Best-Effort 100% BMV Requested to RPV Head BMV Head Head Inspection Perform Only Replacement Inspection and 100% BMV Nozzle UT Exam on Unit 2 Performed Unit 1 Performed Unit 1 Planned Unit 1 100% BMV 100% BMV RPV Head Head Inspection Head Inspection Replacement and Nozzle UT & ECT Exams Farley Nuclear Plant Units 1 & 2 RPV Closure Head Inspection and Replacement Timeline