L-2018-232, Metamic Inservice Surveillance Campaign Summary Report

Metamic Inservice Surveillance Campaign Summary Report

ML18347B364
Person / Time
Site:	Turkey Point
Issue date:	12/13/2018
From:	Hess R Florida Power & Light Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
L-2018-232
Download: ML18347B364 (6)

Text

December 13 , 2018 L-2018-232 U. S. Nuclear Regulatory Commission Document Control Desk Washington, D.C. 20555-00001 Re: Turkey Point Units 3 and 4 Docket Nos. 50-250 and 50-251 Metamic Inservice Surveillance Campaign Summary Report The purpose of this letter is to satisfy the reporting requirements stated in Section 16.2.17.4 of the Turkey Point Updated Final Safety Analysis Report (UFSAR) for submitting to NRC a summary report with the results of each surveillance campaign, six months after completing the campaign.

The attached summary report provides the results of the second Turkey Point in-service surveillance campaign on Metamic Inserts, which was completed on November 29, 2018.

Should there be any questions or comments regarding this information, please contact Mr. Robert Hess at (305) 246-4112.

ess Licensin Manager Turkey Point Nuclear Plant Attachment cc: Regional Administrator, Region II, USNRC Senior Resident Inspector, USNRC, Turkey Point Plant Florida Power & Light Com pany 9760 S.W . 3441n Street Homestead, FL 33035

Attachment to L-2018-232 Florida Power and Light Turkey Point Units 3 and 4 Second In-Service Surveillance Campaign on Metamic Insert Summary Report

Attachment to L-2018-232 1.0 Introduction Metamic is a homogenous, fully dense material with no capillary path through which spent fuel pool water can penetrate. Thus, the dimensions of the insert are not expected to change due to the spent fuel pool environment. The Metamic materials are manufactured to a nominal B-10 loading of 0.0160 g/cm2. After fabrication, random samples are measured by neutron attenuation to confirm the proper B-10 areal density and the homogeneity of the fabrication process.

Consequently, all Metamic materials contain the same nominal value of poison loading.

The purpose of this Metamic Insert Surveillance Program is to demonstrate that the effects of aging of the Metamic inserts are adequately managed such that the intended function(s) will remain consistent with the current licensing basis for the period of extended operation per the requirements of nuclear power plant license renewal rule 10 CFR 54, Requirements for Renewal of Operating Licenses for Nuclear Power Plants.

The Metamic Insert Surveillance Program is credited with managing the aging effect of change in material properties for the Metamic inserts in the spent fuel storage racks. The scope of the Metamic Insert Surveillance Program provides for camera aided visual inspections of inserts, dimensional measurements of inserts, weight measurements of inserts, and neutron attenuation testing of coupons. The 4 year surveillance was completed in 2014 with no anomalies detected.

2.0 Analysis This Metamic Insert Surveillance Program report provides a summary of the results of tests performed at the Turkey Point Unit 3 spent fuel pool. Turkey Point Operations Surveillance Procedure, 0-OSP-034.3 Metamic Insert Surveillance, calls for:

1. Visual inspections of five inserts at 4, 8, 12, 20, and 30 years for indications of corrosion/damage, bubbling, blistering, corrosion pitting, cracking, or flaking.

2. Dimensional measurements of length, width and thickness of two inserts at 4, 12, 20, and 30 years.

3. Weight measurement of two inserts at 4, 12, 20, and 30 years.

4. Neutron attenuation testing of two coupons at 4, 12, 20, and 30 years.

The analysis that follows describes results of the surveillance testing at a Metamic insert utilization time of 8 years. Per the requirements of UFSAR Section 16.2.17, Metamic inserts for the program were selected by considering the following criteria and generally selecting the most challenging conditions:

1. Results of site receipt and pre-installation inspections (i.e., inserts shall be selected if they have more pre-existing conditions);

2. Experience gained during installation (i.e., select inserts that experienced higher insertion or removal forces);

3. Post-Installation spatial distribution of inserts in Region II racks and within the individual storage rack modules (i.e., selecting inserts surrounded by fuel assemblies and located in areas not adjacent to the pit walls);

4. Spatial variations in cooling water flow within the spent fuel pit, specifically considering the effects of the Spent Fuel Pit Cooling system suction and discharge piping;

5. Storage arrangements and the characteristics of fuel assemblies proximate to each insert, especially heat generation rates; 1

Attachment to L-2018-232

6. Noteworthy or unique aspects of Turkey Point fuel pit-related operating experience during the in-service interval, such as atypical water chemistry or impact by a foreign object;

7. Relevant operation experience from other plants.

Testing was performed according to the Operations Surveillance Procedure for the Metamic inserts, 0-OSP-034.3, which outlines the acceptance and functional criteria as follows:

1. Acceptance Criteria

a. Visual inspections of Metamic inserts did NOT identify indications of corrosion/damage, bubbling, blistering, corrosion pitting, cracking, flaking, or other surface based defects.

b. Dimensional measurements of Metamic inserts determined:

Length to be within of +/- 1.0 inches of initial factory acceptance measurements.

Width to be within of +/- 0.5 inches of initial factory acceptance measurements.

Thickness to be within of +0.010 / -0.004 inches of initial factory acceptance measurements.

c. Weight measurements of Metamic inserts determined weight to be within of +/- 10% of initial factory acceptance measurements.

d. Neutron attenuation testing of Metamic coupon did NOT identify a significant decrease in areal density.

1) Significant is defined as any unexpected decrease in areal density from the As-Fabricated condition outside the statistical inaccuracies of the testing methodology.

2) TS 5.5.1.1.g specify that the minimum certified 10B areal density shall be greater than or equal to 0.015 grams 10B/cm2.

2. Functional Criteria None 3.0 Inspection Methods Visual Inspection of Metamic Inserts Visual inspections were performed and documented on five inserts (one welded and four formed) using an underwater video camera by qualified VT-1 inspectors. The surfaces, edges, welds, and attachments were inspected for any visual anomalies. The visual inspection included the left panel, right panel, outside left panel, and outside right panel.

For a formed Metamic insert, it was ensured that:

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Attachment to L-2018-232

1. Mechanical hardware attachments do NOT exhibit anomalies such as cracking, corrosion, pitting corrosion, or other surface defects.

2. The edges, folded region (interior and exterior radii), and the base material of the panel do NOT exhibit anomalies such as cracking, deformation, corrosion pitting, or other surface defects.

3. Metamic to Metamic and Metamic to Aluminum welds do NOT exhibit anomalies such as cracking, deformation, corrosion pitting, or other surface defects.

For a welded Metamic insert, it was ensured that:

1. Mechanical hardware attachments do NOT exhibit anomalies such as cracking, corrosion, pitting corrosion, or other surface defects.

2. The edges, areas near welds (heat affected zone) on external surfaces (that can be seen without disassembly or destructive testing), and the base material of the panel do NOT exhibit anomalies such as cracking or voids, excessive discoloration, corrosion pitting, or other surface defects.

3. Metamic to Metamic and Metamic to Aluminum welds do NOT exhibit anomalies such as cracking, deformation, corrosion pitting, or other surface defects.

4.0 Results The following five inserts were selected for inspection.

Table 4.1 Insert # Formed/Welded Purpose 0274 Formed Four spaces away from discharge piping impingement plate.

N1465101 Welded From region with higher heat generation rates. Welded design.

Cracks noted on outside bend during pre-installation 0023 Formed inspections.

Insert surrounded by fuel assemblies and not adjacent to pit 0085 Formed walls.

0892 Formed Insert experienced higher than normal removal forces.

Visual Inspection of Metamic Inserts Table 4.2 Insert # Pass/Fail Comments One small round rust spot <1/8 diameter. No issues with corrosion 0274 Pass or structure identified.

N1465101 Pass No issues with corrosion or structure identified.

No corrosion issues identified. Cracking at 5th bend outside 0023 Pass diameter and subsequent bend areas down the insert identified.

No corrosion issues identified. Minor area of coatings 0085 Pass scratched/scraped off.

Retaining bar partially dislodged. No corrosion issues identified.

0892 Pass Minor surface scratches.

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Attachment to L-2018-232 All Metamic inserts inspected did not exhibit any unexpected anomalies such as corrosion/damage, bubbling, blistering, corrosion pitting, or flaking. The deviations observed in panels MI-0023 and MI-0892 were due to pre-existing conditions and operating history. The conditions of these two panels does not indicate a degrading trend within the panel population nor does it challenge the operability of these two Metamic inserts. Since no adverse conditions were discovered on the lead Unit (Unit 3), no inspections were performed on the non-lead Unit (Unit 4).

5.0 Conclusion The surveillance program was successfully completed per the requirements outlined in the Turkey Point Operations Surveillance Procedure, 0-OSP-034.3 Metamic Insert Surveillance. Based on the physical observations contained herein, the Metamic panels installed in the spent fuel pool at Turkey Point Nuclear Station are performing their intended design function with respect to neutron absorption and with no evidence of any significant degradation.

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