NL-19-1336, Implementation of BWRVIP-38 and -76 in Lieu of B-N-2 Examinations for Core Support Structures

Implementation of BWRVIP-38 and -76 in Lieu of B-N-2 Examinations for Core Support Structures

ML19308A110
Person / Time
Site:	Hatch
Issue date:	11/04/2019
From:	Gayheart C Southern Nuclear Operating Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
NL-19-1336
Download: ML19308A110 (9)

Text

~ Southern Nuclear Cheryl A. Gayheart Regulatory Affairs Director 3535 Colonnnde Parkway flirmingham . r\L 35143 205 991 .-316 NOV 0 4 2019 cagnyhea @sou thc:rnco.c(llll Docket Nos.: 50-321 NL-19-1336 50-366 U.S. Nuclear Regulatory Commission ATTN : Document Control Desk Washington, D. C. 20555-0001 Edwin I. Hatch Nuclear Plant Units 1 and 2 Implementation of BWRVIP-38 and -76 in lieu of B-N-2 Examinations for Core Support Structures Ladies and Gentlemen:

Pursuant to 10 CFR 50.55a(z)(1 ), Southern Nuclear Operating Company (SNC) requests Nuclear Regulatory Commission (NRC) authorization of proposed Alternative HNP-ISI-ALT 10. This Alternative corrects specific inconsistencies between the required examinations per HNP-ISI-ALT-05-04, and those examinations required per the applicable Boiling Water Reactor Vessel and Internals Project (BWRVIP) guidelines.

By letter dated January 22, 2019, the NRC authorized the use of proposed Alternative HNP-ISI-AL T-05-04 for Edwin I. Hatch Nuclear Plant (HNP), Units 1 and 2. This authorization allowed use of BWRVIP guidelines as an alternative to certain requirements of Section XI of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (B&PV Code) for the inservice inspection (lSI) of reactor pressure vessel interior surfaces, attachments, and core support structures.

Subsequent to the NRC authorization of HNP-ISI-ALT-05-04, SNC identified that certain examinations pursuant to the HNP Units 1 and 2 shroud and shroud repair were not clearly identified, and that the relationship between the ASME Code, BWRVIP, and previous HNP submittals regarding the shroud repair modification were not sufficiently delineated. This Alternative will provide the necessary clarity of HNP Unit 1 and Unit 2 specific design characteristics of the shroud support structure, and its relationship with the applicable BWRVIP guidance and previous HNP correspondence.

This letter contains no NRC commitments. If you have any questions, please contact Jamie Coleman at 205.992.6611.

Respectfully submitted, CAG/RMJ

U. S. Nuclear Regulatory Commission NL-19-1336 Page 2

Enclosure:

Alternative HNP-ISI-ALT-05-10 Cc: Regional Administrator, Region II NRR Project Manager- Hatch Senior Resident Inspector- Hatch RTYPE: CHA02.004

Edwin I. Hatch Nuclear Plant Units 1 and 2 Implementation of BWRVIP-38 and -76 in lieu of B-N-2 Examinations for Core Support Structures Enclosure Alternative HNP-ISI-ALT-05-10

Enclosure to N L-19-1336 Alternative HNP-ISI-ALT-05-1 0

1. ASME Code Component(s) Affected Code Class: ASME Section XI Code Class 1 Component Numbers: None Code

References:

ASME Section XI, 2007 Edition with 2008 Addenda Examination Category: B-N-2 Item Number(s): B13.30, and B13.40

2. Requested Approval Date Approval is requested by January 1, 2021

3. Applicable ASME Code Requirements Per the NRC Approval of HNP-ISI-ALT-05-04 (Reference H.), the following BWRVIP requirements apply to the items listed below for Hatch Nuclear Plant (HNP) Units 1 and 2:

ASME Item Applicable BWRVIP BWRVIP BWRVIP No. Table Component BWRVIP Exam Scope Exam Type Frequency IWB-2500-1 Document B13.30 Shroud BWRVIP-38, Weld H9 EVT-1 or UT Maximum of 6 Support 3.1 .3.2, including years for EVT -1, (Weld H9) Figures 3-2 gussets Maximum of 10 including and 3-5 years for UT gussets Note: Hatch Unit 2 configuration does not have gussets.

B13.40 Integrally BWRVIP-38, Shroud EVT-1 or UT Based on as-found Welded 3.1.3.2, support conditions, to a Core Figures 3-2 welds H8 maximum 6 years Support and 3-5 and H9 for EVT-1, 10 years Structure including for UT where gussets accessible

4. Reason for Request

In accordance with 10 CFR 50.55a(z)(1 ), HNP Units 1 and 2 previously submitted a request for NRC approval of alternative HNP-ISI-ALT-05-04 (ML18172A281) to use of the Boiling Water Reactor Vessel Internals Project (BWRVIP) guidelines in lieu of ASME Code Section XI B-N requirements. The NRC authorized this alternative January 22, 2019 (ML19011A010). Upon review of particular details in that alternative, SNC identified that E-1

Enclosure to NL-19-1336 Alternative HNP-ISI-ALT-05-1 0 certain examinations pursuant to the HNP Units 1 and 2 shroud and shroud repair were not clearly identified, and that the relationship between the ASME Code, BWRVIP, and previous HNP submittals regarding the shroud repair modification were not sufficiently delineated.

This alternative is therefore being submitted to provide the necessary clarity of HNP-specific design characteristics of the shroud support structure and its relationship with BWRVIP guidance and previous HNP correspondence. This will allow staff review of these specific details to ensure future misinterpretation is avoided.

The BWRVIP Inspection and Evaluation (I&E) Guidelines recommend specific inspection by BWR owners to identify material degradation with BWR components. The BWRVIP I&E Guidelines focus on specific and susceptible components, specify appropriate inspection methods capable of identifying known or potential degradation mechanisms, and require re-examination at appropriate intervals. The scope of the I&E Guidelines exceeds that of ASME Section XI and, in most instances, include components that are not part of the ASME Section XI jurisdiction.

Use of this proposed alternative will maintain an adequate level of quality and safety and avoid duplicate or unnecessary inspections, while conserving radiological dose.

5. Proposed Alternative and Basis for Use Proposed Alternative SNC requests to modify the examination requirements for HNP Unit 1 and Unit 2 welds H8 and H9 as approved in Reference H. The modified examination requirements are shown in Table 1.

Basis for Use B13.30 - Interior Attachments Beyond the Beltline Region BWRVIP-38 governs the industry requirements for H9. BWRVIP-38 clearly states in Section 2.1.2 that the Unit 2 H9 weld is not addressed since it is a low alloy steel weld that is not susceptible to IGSCC and concludes that the ASME Code Section IWB-2500 B-N-2 core support structure examinations (813.40) are sufficient for degradation monitoring.

B13.40 - Core Support Structure The previously approved alternative, ISI-ALT-05-04, did not include the H8 weld as structurally replaced by the shroud tie rod repair. References C. and E. and NRC authorizations D. and F. establish that the shroud repair also includes the H8 weld for HNP Units 1 and 2.

E-2

Enclosure to NL-19-1336 Alternative HNP-ISI-ALT 10 For HNP Unit 2, no augmented examinations are required per BWRVIP-38 for the H9 weld as it is not susceptible to IGSCC. In SNC's response to the staff's request for information regarding the absence of any reference to gusset inspections in the HNP-2 shroud stabilizer modification submittal by stating in reference G.:

"Plant Hatch Unit 2 was constructed with a 8.8" thick shroud support plate fabricated from low alloy steel and clad with Type 304 stainless steel on the bottom (lower plenum side) and alloy 82/182 on the top (annulus side). This thick plate design is unique to Plant Hatch Unit 2 and structurally takes the place of the thinner support plate/gussets or thinner support plate/support leg configurations found in other BWRs. For this reason no gusset plate examinations are specified. The Unit 2 shroud support is exempted from the inspection criteria of BWRVIP-38. Section 2.1.2 of BWRVIP-38 clearly states this and that Code examinations are adequate since the shroud support is low alloy steel and thus not susceptible to IGSCC. A collet/clevis pin assembly was installed in 1995 to provide a lower attachment for each tie rod assembly. These assemblies have no welded components."

Therefore, for Hatch Unit 2, the ASME Code Section XI B-N-2 item B 13.40 visual (VT -3) examination will continue to be performed for the accessible shroud support plate surfaces from the H8 weld up to and including the H9 weld.

6. Duration of Proposed Alternative This proposed alternative will be used for the Fifth Ten -Year Interval of the lnservice Inspection Program for HNP Units 1 and 2.

7. Precedents Precedents from HNP-ISI-ALT-05-04 are still applicable.

8. References A. US NRC Letter to BWRVIP, dated July 24, 2000, "Final Safety Evaluation of the "BWR Vessel and Internals Project, BWR Shroud Support Inspection and Flaw Evaluation Guidelines (BWRVIP-38), "EPRI Report TR-108823 (TAC NO. M99638).

B. BWRVIP-76NP, Revision 1: "BWR Vessel and Internals Project BWR Core Shroud Inspection and Flaw Evaluation Guidelines," May 2011 (ML11195A182).

C. SNC Letter NL-07-1155; Edwin I. Hatch Unit 1 Proposed Modification of the Unit 1 Core Shroud Stabilizer Assemblies, dated August 14, 2007 (ML072280298)

D. US NRC letter to Mr. Dennis R. Madison: "Edwin I. Hatch Nuclear Plant, Unit No. 1 (Hatch-1), Safety Evaluation for Reactor Core Shroud Relief Request, dated March 26, 2008 (ML080570109)

E. SNC Letter NL-08-1301; Edwin I. Hatch- Unit 2 Request for Authorization Under Provision of 10 CFR 50.55a(a)(3)(i) for Modification of the Unit 2 Core Shroud Stabilizer Assemblies, dated September 3, 2008 E-3

Enclosure to NL-19-1336 Alternative HNP-ISI-ALT-05-10 F. US NRC letter to Mr. Dennis R. Madison: "Edwin I. Hatch Nuclear Plant ,Unit No. 2 (Hatch-2), Safety Evaluation and Request for Additional Information for Reactor Core Shroud Relief Request, dated February 13, 2009 (ML090330216)

G. SNC letter NL-08-1897, Edwin I. Hatch- Unit 2 Response to NRC Request for Additional Information Regarding Modification of the Core Shroud Stabilizer Assemblies, dated December 19, 2008 (TAG No. MD9579)

H. US NRC letter to Ms. Cheryl A. Gayheart: "Edwin I. Hatch Nuclear Plant, Unit Nos 1 and 2- Proposed Alternative HNP-ISI-ALT-05-04 for the Implementation of BWRVIP Guidelines (EPID L-2018-LLR-0099)", dated January 22, 2019 (ML19011A010)

E-4

Enclosure to NL-19-1336 Alternative HNP-ISI-ALT 1 0 Table 1 HNP Units 1 and 2 ASME Item Applicable BWRVIP BWRVIP No. Table Component BWRVIP BWRVIP Frequency Exam Scope Exam Type IWB-2500-1 Document 813.30 Interior BWRVIP-38, Weld H-9 EVT-1 or UT Maximum of 6 years for EVT -1, Maximum of Attachments 3.1.3.2, 10 years for UT beyond Beltline - Figures 2-5, 3-Shroud Support 2 and 3-5 (HNP-1) 813.30 Interior BWRVIP-38, Weld H-9 None Per BWRVI P-38, H9 is not susceptible to Attachments 2.1.2 IGSCC, continuation of 813.40 visual (VT-3) beyond Beltline - Figures 2-2 each ten-year interval is sufficient for Shroud Support degradation monitoring (HNP-2) 813.40 Integrally BWRVIP-38, Shroud EVT-1 or UT Based on as-found conditions, to a maximum Welded Core 3.1.3.2, support weld of H9 and 6 years for EVT-1 , 10 years for UT where Support Figures 2-5, H8 and H9 gussets accessible Structures 3-2, 3-5 and gussets (HNP-1) BWRVIP-76 Shroud None for H8 Shroud hardware examination scope and R1-A, 3.5 hardware EVT -1 of four frequency is in accordance with references C (repair and gussets and D; performed in lieu of shroud horizontal components), anchorages serving as welds H1-H8.

3.6 anchorages.

(anchorages)

E-5

Enclosure to NL-19-1336 Alternative HNP-ISI-ALT-05-10 Table 1 HNP Units 1 and 2 ASME Item Applicable BWRVIP BWRVIP No. Table Component BWRVIP BWRVIP Frequency Exam Scope Exam Type IWB-2500-1 Document 813.40 Integrally BWRVIP-38, Shroud VT-3 of Each 10-year interval Welded Core 2.1.2, Figure 2- support from accessible Support 2 weld H8 up surfaces Structures to and (HNP-2) including H9 BWRVIP-76 Shroud None Shroud hardware examination scope and R1-A, hardware frequency is in accordance with references E Section 3.5 and F; performed in lieu of shroud horizontal (repair welds H1-H8. HNP-2 has no "highly stressed" components), anchorages.

Section 3.6 (anchorages)

E-6