ML17290B137

Recommendations for Future Inspection - Replacement Steam Dryer. with GE Hitachi Nuclear Energy Report 0000-0125-6316-R2-NP

ML17290B137
Person / Time
Site:	Grand Gulf
Issue date:	10/17/2017
From:	Neve D Entergy Operations
To:	Document Control Desk, Office of Nuclear Material Safety and Safeguards, Office of Nuclear Reactor Regulation
Shared Package
ML17291A089	List: ML17290B137
References
GNR0-2017/00067
Download: ML17290B137 (22)

Text

Attachment 2 of this letter contains proprietary Information - Attachment 2 is withheld from public disclosure per 10CFR2.390

---Entergy Entergy Operations, Inc.

P.O. Box756 Port Gibson, Mississippi 39150 Douglas A. Neve Regulatory Assurance Manager Grand Gulf Nuclear Station Tel: 601-437-2103 GNR0-2017/00067 October 17, 2017 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D.C. 20555

SUBJECT:

Grand Gulf Nuclear Station (GGNS) Recommendations for Future Inspection -

Replacement Steam Dryer Grand Gulf Nuclear Station Unit 1 Docket No. 50-416 License No. NPF-29

REFERENCES:

NRC Integrated Inspection Report 05000416/2017002 and 7200050/2017007 and Notice of Non-cited Violation August 3, 2017

Dear Sir or Madam:

The purpose of this letter is to provide the Grand Gulf Nuclear Station (GGNS)

Recommendations for Future Inspections. The two attached files contain, respectively, the public and proprietary versions of the document.

This letter contains no new commitments. If you have any questions concerning the content of this letter, please contact Mr. Douglas A. Neve at 601-437-2103.

Douglas A. eve Regulatory Assurance Manager DAN/rfp I Attachments: 1. 0000-0125-6316-R2-NP Grand Gulf Nuclear Station (GGNS) Recommendations for Future Inspections - Replacement Steam Dryer Public Version

2. 0000~0125-6316-R2-P Grand Gulf Nuclear Station (GGNS) Recommendations for Future Inspections - Replacement Steam Dryer Proprietary Version

GNR0-2017/00067 Page 2 of 2 WITHOUT ATTACHMENTS cc: NRC Senior Resident Inspector Grand Gulf Nuclear Station Port Gibson, MS 39150 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 U.S. Nuclear Regulatory Commission, Region IV ATIN: A~ting- Mr. Scott Morris, Regional Administrator 1600 East Lamar Boulevard Arlington, TX 76011-4511

Attachment 1 To GNR0-2017/00067 GGNS 0000-0125-6316;.R2-NP Grand Gulf Nuclear Station (GGNS) Recommendations for Future Inspections - Replacement Steam Dryer Public Version

GE Hitachi Nuclear Energy 0000-0 l 25-6316-R2-NP PLM Specification OOON0574 Revision 1 Revision2 September 2017 Non-Proprietary Information - Class I (Public)

Grand Gulf Nuclear Station (GGNS)

Recommendations for Future Inspection -

Replacement Steam Dryer Copyright 2017 GE-Hitachi Nuclear Energy Americas LLC All Rights Reserved

0000-0 l 25-6316-R2-NP Non-Proprietary Information- Class I (Public)

INFORMATION NOTICE This is a non-proprietary version of the document 0000-0125-6316-R2-P which has the proprietary information removed. Portions of the document that have been removed are indicated by an open and closed bracket as shown.here (( )).

IMPORTANT NOTICE REGARDING CONTENTS OF TIDS REPORT Please Read Carefully The design, engineering, and other information contained in this document is furnished for the purposes of providing recommendations for future inspection.s on the replacement steam dryer at Grand Gulf Nuclear Station in proceedings before the U.S. Nuclear Regulatory Commission (NRC). The only undertakings of GEH with respect to information in this document are contained in the contracts between GEH and its customers or participating utilities, and nothing contained in this document shall be construed as changing that contract.* The use of this information.by anyone for any purpose other.than that for which it is intended, is* not authorized; and with respect to any unauthorized use, GEH makes no representation or warranty, and assumes no liability as to the completeness, accuracy, or usefulness of the information contained in this document.

ii

0000-0125-6316-R2-NP Non-Proprietary Information- Class I (Public)

Table of Contents

1. Introduction ......................... ~ ........................................................................................ 1 1.1 Original Grand Gulf Dryer .......................................................................................... 1 1.2 Replacement Dryer Desig:ri .......................................................................................... 2 1.3 Modifications Made for Grand Gulf ............................................................................ 2 1.4 Design Improvements to BWR/4 Replacement Desig:ri ............................................... 2

2. Inspection Recommendations ...................................................................................... 3 2.1 Prior to the First Operating Cycle ................................................................................ 3 2.2 Inspections During the First Po.wer Ascension ............................................................ 3 2.3 Final Assessment at EPU ............................................................................................. 4 2.4 After One Operating Cycle .......................................................................................... 4 2.5 Scope Expansion .......................................................................................................... 5 2.6 Subsequent Re-Inspections .......................................................................................... 5

3. References ....... ~*.........1

• • • • ~ ********************************************************************************************** 6 List of Tables Table 1. General Description oflnspection Locations and Frequency oflnspections .............. 7 Table IA. Description of Inspection Locations and Frequency of Inspections for Steam Dryer (( )) Remnants (Reference 5) .......................... 8 Table 2. Description of Inspection Locations ............................................................................ 9 List of Figures Figure 1. Nomenclature for Major Components (Dryer Top) ................................................... 12 Figure 2. Nomenclature for Major Components (Dryer Top Internals) .................................... 13 Figure 3. Nomenclature for Major Components (Dryer Bottom) .............................................. 14 Figure 4. Typical (( )) Remnants After Removal (Reference 5) .......................*..................................... :................................................ 15 iii

0000-0 l 25-6316-R2-NP Non-Proprietary Information - Class I (Public)

Revision Status 0 July 2011 Original Release.

Added recommendation for ((

1 December 2013

)) remnants after removal.

Added markings to indicate GEH proprietary 2 September 2017 information to support submittal of the document to theNRC.

iv

0000-0125-6316-R2-NP Non-Proprietary Information- Class I (Public)

1. Introduction This document provides recommendations for future inspections of the Grand Gulf Nuclear Station replacement steam dryer.

The replacement steam dryer design .utilizes materials and fabrication processes that are

• expected to result in significantly improved resistance to stress corrosion cracking. Therefore, these inspection recommendations focus primarily on the locations. that may be susceptible to fatigµe from flow-induced vibration (FIV). The locations identified are those indicated to have relatively significant cyclic loading during the dryer's operation, as determined by detailed stress analyses (Reference 1).

In addition, this document provides recommendations for future inspections of the remnants of the (( )), on the Grand Gulf Unit 1 steam dryer. The (( )) was associated with the steam dryer

(( )) measurements recorded during the initial reactor startup operatfon in Spring 2012. The (( )) removal was performed during the Spring 2014 outage and included the removal of ((

)) with the following items remaining on the dryer surface

((

))

The (( )) removal included installation of a ((

))

1.1 Original Grand Gulf Dryer The original. Grand Gulf steam dryer is a curved hood six-bank dryer. Inspections of the original Grand Gulf dryer have reported only a few indications. Three indications have been found on the dryer support ring. These indications were determined to be intergranular stress corrosion cracking, which is common for support rings in dryers of this vintage. Other indications were found on the lifting eye-to-lifting rod tack welds. These cracks were caused by low cycle fatigue during handling of the dryer, not high cycle fatigue (HCF) during power operation of the reactor. When compared to other curved hood dryers, the Grand Gulf indications have been minor.

Other original equipment curved hood dryers have required repairs to drain channels, end plates, hoods and tie bars to address fatigue cracking. Since 2004 the interiors of several curved hood dryers have been inspected. These inspections have shown cracking at the junction of the interior hood supports, the hood panel and base plate, as well as the junction of the interior hood support and the trough. The configuration at these locations is very stiff (the junction of three perpendicular planes). It is believed that the cracks formed early in life and once formed, the 1

0000-0125-6316-R2-NP Non-Proprietary Information - Class I (Public) cracks introduced sufficient flexibility in the structure. Of those affected dryers that have been re-inspected, the results indicate that the existing cracks are relatively stable.

1.2 Replacement Dryer Design The Grand Gulf replacement steam dryer design is based on the design of a curved hood six bank replacement dryer used in a* prototype BWR/4 reactor. To satisfy the current minimum alternating stress ratio (MASR) and maximum allowable stress limits, the BWR/4 replacement dryer design ((

)) In addition, ((

)) This steam dryer also uses ((

)) to improve the stress distribution and move the welds away from the stress concentration at these panel junctjons. The replacement steam dryer also uses an improved ((

)) As a result, .

the BWR/4 prototype replacement steam dryer design is significantly more robust than the steam dryer it replaces. Both the Grand Gulf reactor vessel and the. BWR/4 reactor vessel where the BWR/4 *prototype replacement dryer was installed have the same internal diameter. Thus the Grand Gulf replacement steam dryer design remains essentially unchanged from the BWR/4 prototype design. Differences between the BWR/4 dryer and the Grand Gulf replacement steam dryer are discussed in the section below. The Grand Gulf replacement dryer is very similar in profile to the original Grand Gulf dryer with the addition of the improvements incorporated in the (( )) design.

1.3 Modifications Made for Grand Gulf Several minor changes were made to the BWR/4 prototype dryer design to match the fit and form of the original Grand Gulf steam dryer. First, the Grand Gulf reactor design uses six vessel supports for the steam dryer as opposed to four supports for the BWR/4 design. The six support locations are included in the Grand Gulf replacement steam dryer design. The steam dryer skirt was lengthened by 9.5 inches to match the original Grand Gulf dryer. The Grand Gulf reactor is designed with six hold-dowrt locations on the vessel head to hold the dryer in place during a postulated inain steam line (MSL) break.. Four of these are the lifting rods as in the BWR/4 design. .The additional two hold-down channels in the BWR/6 design are located in. the end closure plates between the two center banks. ((

))

1.4 Design Improvements to BWR/4 Replacement Design A minor change to the BWR/4 prototype steam dryer was ((

)), reducing the stress in this 1

location. (( ))

2

0000-0125-6316-R2-NP Non-Proprietary Information - Class I (Public)

2. Inspection Recommendations 2.1 Prior to the First Operating Cycle All fabrication records should be inventoried, reviewed and archived. The records shall be sufficient to comprehensively define the condition of all structural components and their attachment welds, so that they provide a basis for comparison of all critical areas for future inspections. The records shall include documentation pertaining to any deviations or structural alterations that may occur during shipment from the fabricator, final assembly on the reactor floor, and installation in the reactor.

2.2 Inspections During the First Power Ascension During startup and power ascension above current licensed thermal power (CLTP), MSL strain data will be recorded and dryer loads will be determined and monitored. ((

)) The primary function of the monitoring program is to confirm that the pressure loading on the steam dryer during power operation is consistent with the pressure_ loading assumed in the* structural fatigue evaluation and to confirm that the steam dryer can adequately withstand the acoustic and hydrodynamic pressure loads. The primary objectives are as follows:

• Provide a controlled approach to power ascension.

• Provide start-up test acceptance criteria for comparison with measured readings during power ascension.

• Confirm the steam dryer analyses performed for the extended power uprate (EPU) conditions.

The power ascension test program (PATP) includes:

((

))

• Forwarding to the Nuclear Regulatory Commission (NRC) the evaluation results taken at the CLTP baseline, halfway through the power ascension, and at the end of the power ascension test plan.

During power ascension, Entergy plans (and GEH recommends) to ((

3

0000-0125-6316-R2-NP Non-Proprietary Information- Class I (Public)

)) power ascension will stop and power will be lowered to a known acceptable level.

The acceptability of the steam dryer for the measured loading would then be evaluated and revised acceptance criteria defmed as required. The duration of the holdpoints will be .

determined by the time required to obtain the specified data, complete the evaluation, and obtain the required level of approval.

2.3 Final Assessment at EPU Once EPU conditions are obtained and data collected at EPU conditions, a fmal stress evaluation will be performed and submitted to the NRC. Station operating procedures will be used to.

monitor plant parameters potentially indicative of steam dryer failure as recommended in General Electric Services Information Letter (SIL) 644, "BWR Steam Dryer Integrity" (Reference 2).

Results will be reviewed and evaluated on a defmed basis to monitor ((

)).

2.4 After One Operating Cycle 2.4.1 General Area Examination Inspection personnel planning or evaluating the steam dryer inspections should review the Reference 3, 4, 5, and 6 assembly and modification drawings, and become familiar with the steam dryer configuration and weld locations. It is recommended that the replacement steam dryers be visually examined during each scheduled refueling outage until at least two full operating cycles at full EPU conditions have been achieved. A general area visual examination (VT-3) should be performed over all areas that are accessible from the exterior of the steam dryer to confirm that the replacement steam dryer has no obvious cracking, significant deformation or missing parts.

In order to be consistent with previous inspections, the examination resolution requirements shall be per Reference 7. This utilizes the 1/32 iuch black line on an 18% neutral gray card as reference for VT-1. Because there are no specific VT-3 resolution requirements per Reference 8, the resolution requirements of the VT-3 examinations shall be the same as those forVT-1.

2.4.2 Locations Potentially Subject to Fatigue Tables 1 and 2 list locations that are considered the most susceptible for fatigue cracking based on boiling water reactor (BWR) dryer experience and the stress analysis (Reference 1).

Accessible weld and weld heat affected zone base metal surfaces of the replacement steam dryer should be visually inspected during each scheduled refueling outage until at least two full operating cycles at full EPU conditions have been achieved. The resolution standard for these visual examinations , should be "best effort VT-1" in accordance with Section 5.2 of BWRVIP-139 (Reference 9).

4

0000-0125-6316-R2-NP Non-Proprietary Information - Class I (Public) 2.4.3 Vessel Support Lugs In consideration of the [ [ )), all six of the vessel steam dryer support lugs .should be visually (VT-1) examined. This examination should include the entire lug attachment weld to the vessel, and at least Vi-inch of adjacent lug weld heat affected zone material. In addition, the top surface of the lug at the inboard end where the dryer weight is supported (bearing area) and at least one inch of the vertical lug

• surface adjacent' to the dryer bearing area should be examined.

2.4.4 Locations Prone to Handling Damage There are a number of locations thought to be prone to handling damage (e.g., local deformation, and gouges, rolled metal and tom welds). These locations are the lower ring at the guide rod and vessel support bracket azimuths and at the middle support ring where the vessel support brackets land. These locations should be examined at each outage when the steam dryer is removed. A VT-3 resolution is sufficient for these examinations.

2.4.5 Remnant of Removed (( ))

\

This examination is applicable to the replacement dryer after the [ [ ))

has been removed. Items listed in Table lA, the remnants of the removed ((

)) (References 5 and 6), should be visually inspected for loose parts and weld cracks. Except for the (( )), this equipment does not provide any structural support or pressure retention for the replace~ent steam dryer. Except for the [ [ )), a* VT- 3 resolution is sufficient for these examinations. The weld for the

(( )) should be visually (VT-1) examined.

2.5 Scope Expansion 1

Should a relevant indication be found in any of the Table 1 and 2 weld locations during the recommended inspections in Section 2.4.2, similar locations (welds) in Table 1 and 2 should be examined during the same outage. Scope expansion should include as a minimum the mirror symmetric dryer locations that correspond to the component with the relevant indication. If one or more of the mirror symmetric dryer locations also shows a relevant indication, all dryer locations that contain this type of component should be inspected. Should a relevant indication be found during the general area examination in a location not specifically identified in Table 1 and 2, the scope of the inspection should be expanded to include all similar locations (e.g., mirror symmetric dryer location). The resolution standard for these visual examinations should be "best effort VT-1" in accordance with Section 5.2 of BWRVIP-139 (Reference 9).

2.6 Subsequent Re-Inspections 2.6.1 Fatigue Locations The VT-1 inspections described m Section 2.4.2 should be repeated during subsequent 1

See Section 3.2 in BWRVIP-03 (Reference 7) for definition of relevant indication.

5

0000-0125-6316-R2-NP Non-Proprietary Information - Class I (Public) refueling outages as indicated in Table 1. Inspection of additional regions will only be required by the scope expansion requirement of Section 2.5. The basis of these recommendations is engineering judgment considering prior EPU experience. If relevant indications are reported in any inspection, the inspection interval noted for that location in Table 1 shall be reduced to each subsequent refueling outage until *. the indication is determined to have stabilized.

2.6.2 All Other Areas The inspections recommended in Sections 2.4.1 (VT-3 of dryer exterior), 2.4.3, and 2.4.4 are recommended at each refueling outage. Inspections recommended in Section 2.4.5 should follow the frequency recommendations found in Table lA.

2.6.3 lJases of Inspection Recommendations The bases for these inspection recommendations are:

1. Typical BWR practice, engineering judgment, experience with original equipment steam dryers, and industry recommendations (BWRVIP-139).

2. Fatigue cracking experience with BWR steam dryers.

3. (( )), which suggests additional.

attention to potential damage in the region of the steam dryer support lugs.

4. Removal of (( ]l.

3. References

1. GE Hitachi Nuclear Energy,* "Grand Gulf Replacement Steam Dryer Fatigue Stress Analysis Using PBLE Methodology," NEDC-33601P, Revision 0, September 2010.

2. GE SIL-644, "BWR Steam Dryer Integrity."

3. (( ))

4. (( ))

5. (( ))

6. (( ))

7. BWRVIP-03, "BWR Vessel and Internals Project, Reactor Pressure Vessel and Internals Examination Guideline.s," Latest Edition.

8. ASME Boiler and Pressure Vessel Code Section XI, "Rules for In-Service Inspection of Nuclear Power flant Components," 2001 Edition, to and including the 2003 Addenda.

9. BWRVIP-139, "BWR Vessel and Internals Project, Steam Dryer Inspection and Flaw Evaluation Guidelines," 1011463, Latest Edition.

6

0000-0125-6316-R2-NP Non-Proprietary Information - Class I (Public)

Table 1. General Description of Inspection Locations and Frequency of Inspections

((

))

7

\

0000-0125-6316-R2-NP Non-Proprietary Information - Class I (Public)

Table lA. Description of Inspection Locations and Frequency of Inspections for Steam Dryer (( )) Remnants (Reference 5)

((

))

Table 1 Notes:

F = Each refueling outage until at least two full operating cycles at full EPU operating conditions have been achieved. Inspection areas that *show no relevant indications during EPU inspections should be re-inspected at a frequency not to exceed five refueling cycles.

LF = Each refueling outage until at least two full operating cycles at full EPU operating conditions have been achieved. Inspection areas that show no relevant indications during EPU inspections should be re-inspected at a frequency not to exceed five refueling cycles. Fifty percent of components should be inspected in each subsequent re-inspection outage. .

IN = Each refueling outage until at least two full operating cycles at full EPU operating conditions have been achieved. Inspection areas that show no relevant indications during EPU inspections should be re-inspected at a frequency not to exceed five refueling cycles. Twenty-five percent of components should be inspected in each subsequent re-inspection outage.

Table lA Note 2:

((

))

8

0000-0125-6316-R2-NP Non-Proprietary Information - Class I (Public)

Table 2. Description of Inspection Locations

((

9

0000-0125-6316-R2-NP Non-Proprietary Information - Class I (Public) 10

0000-0 l 25-6316-R2-NP Non-Proprietary Information - Class I (Public)

))

11

0000-0125-6316-R2-NP Non-Proprietary Information - Class I (Public)

((

))

Figure 1. Nomenclature for Major Components (Dryer Top) 12

0000-0125-63 l 6-R2-NP Non-Proprietary Information - Class I (Public)

((

))

Figure 2. Nomenclature for Major Components (Dryer Top Internals) 13

0000-0125-6316-R2-NP Non-Proprietary Information - Class I (Public)

((

))

Figure 3. Nomenclature for Major Components (Dryer Bottom) 14

0000-0125-6316-R2-NP

. Non-Proprietary Information- Class I (Public)

((

))

Figure 4. Typical (( )) Remnants After Removal (Reference 5) 15