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12-14 NEI EPRI Presentation NRC Public Meeting 16-03 R1
	ML23347A178
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Site:	Nuclear Energy Institute
Issue date:	12/13/2023
From:	; Nuclear Energy Institute
To:	Gerond George; Licensing Processes Branch
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	Download: ML23347A178 (1)
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©2023 Nuclear Energy Institute 2 Establish an industry-wide program (i-LAMP) that provides reasonable confidence that any future degradation of BORAL neutron absorber materials is reliably detected and addressed, thereby providing continued assurance of public health and safety.

Bridge the gap between licensees who currently retain a BORAL coupon surveillance program and those that do not.

Provide the technical basis for a regulatory framework that encourages adoption of and ongoing participation in i-LAMP by all licensees utilizing BORAL.

Industry Objectives for NEI 16-03, Rev. 1

Requires licensees without a Boral coupon surveillance program to establish participation in i-LAMP.

Maximizes the value of the i-LAMP program by associating each spent fuel pool that does not have a coupon surveillance program with every other spent fuel pool that does.

Objective for Todays Meeting

The NRC staff approves the NEI 16-03, Rev. 1, methodology for employing i-LAMP as an alternative monitoring strategy only if the i-LAMP program provides for the licensee to perform a detailed analysis of its SFP and BORAL material considering the parameters described in NEI 16-03 Rev 1. The i-LAMP alternative strategy is unacceptable unless a plant-specific analysis verifies that SFP conditions and BORAL parameters are consistent with those of a sibling SFP or are bounded by those of an older SFPs BORAL. This limitation is imposed to address the discussion in NEI 16-03 Rev.1 of a 2-bin system in which plants without coupons are assumed to be bounded by those with coupons.

Draft Safety Evaluation Report

The NRC staff approves the NEI 16-03, Rev. 1, methodology for employing i-LAMP as an alternative monitoring strategy if a plant-specific licensee analysis demonstrates that its SFP conditions and BORAL parameters are represented in the i-LAMP database and that there are no degradation trends identified by the i-LAMP program that are relevant to the licensee's BORAL. If a relevant trend is identified, the licensee shall identify one or more siblings with consistent parameters and will monitor the sibling(s) BORAL performance trends within its corrective action program.

Draft Safety Evaluation Report

©2023 Nuclear Energy Institute 6 After several decades of service in spent fuel pools, no degradation in the neutron absorbing safety function of BORAL has been identified to date. This effectively diminishes the meaning of the term bounded by in this case, with respect to age.

No correlation between service time or age has been established as relevant to any potential degradation mechanism. Other service parameters such as water chemistry, BORAL fabrication lot, or rack design could ultimately be the primary of cause of any future signs of degradation. Thus, establishment of sibling relationships is possible but not currently warranted.

i-LAMP will equip the industry with the tools to identify appropriate siblings if and when degradation is detected.

Basis for Revised Wording

Implementation Language in Draft SE Section 1.0: the NRC staff is not proposing to issue a regulatory guide to endorse NEI 16-03. Instead, as stated in this Safety Evaluation (SE), the NRC staff is treating NEI 16-03, Rev. 1, as a topical report, and as described below, the NRC staff has determined that NEI 16-03, Rev. 1 is acceptable, with the limitation described below, for referencing in a license amendment request (LAR) that includes the information described below in Section 4.0 of this SE.

Section 3.6: Based on the foregoing, the NRC staff has determined that NEI 16-03, Rev.1 is acceptable for referencing in a LAR requesting approval of a NAM monitoring program.

Section 5.0 (paragraph 2): The NRC staff finds that the requirements would be satisfied with respect to NAMs and the NAM monitoring program if referenced in an LAR requesting use of the program Section 5.0 (paragraph 3): Each licensee adopting NEI 16-03, Rev. 1 will need to implement it in accordance with its plant-specific processes and licensing basis. This will involve review under the plant commitment control process and 10 CFR 50.59. Either of these processes could result in the need for a plant-specific license amendment request. Each licensee will need to make its own evaluation in this regard under its site-specific change control program.

Section 1.0, Section 3.6, and paragraph 2 of Section 5.0 should be updated to allow for i-LAMP implementation via plant-specific processes per individual plant licensing bases and to eliminate confusion with paragraph 3 of Section 5.0.

Discussion Items - Other questions/comments Section 3.3.2: With respect to the concept of a 2 bin approach, the staff finds that NEI 16-03 Rev. 1 represents an overly simplistic approach.

Simple may be more appropriate for implementation and will enable population trending approach.

Suggestion: represents a generic approach.

Throughout document, consider using consistent with rather than bounding, given no observed trends in any of the parameters described in NEI 16-03 Rev 1.

w w w. e p r i. c o m Guidance for Monitoring of Fixed Neutron Absorbers in Spent Fuel Pools Hatice Akkurt Used Fuel and High-Level Waste Management Program, EPRI NRC Public Meeting December 14, 2023

2 Draft SE: i-LAMP Components i-LAMP not only relies on coupon database but also has other vital components to be considered an effective monitoring program Section 3.3.1, page 7, line 31: The core of i-LAMP is an SFP coupon database i-LAMP general layout

3 Technical Basis for an Effective Aging Management Program Work has been published in 7 EPRI reports and > 25 papers To date, no significant degradation; no dependence on one parameter or parameters Operating Experience:

Monitoring Results*

Operating Experience:

Actual Panel Analysis**

Consequence Analysis***

Laboratory Tests Laboratory: Accelerated Corrosion Test (to be published soon 3002023975)

Actual panels, coupons, and in-situ measurements from SFP: Zion comparative analysis (3002008196 and 3002008195)

Modeling and Simulation: Evaluation of Impact of Blister and Pits (3002013119)

Evaluation of Panels from an Operating SFP (3002018497) i-LAMP proposal (3002013122) and i-LAMP final report (3002018497)

Coupon and in situ

- Panels from Zion & Operating SFP

- - Evaluation of impact of blister and pits on SFP reactivity

4 Draft SE: i-LAMP Components Sister/Sibling pool criteria will depend on the analysis when/if trends are established since i-LAMP is a learning program Section 3.3.1, page 7, line 31: The core of i-LAMP is an SFP coupon database Suggested change:

Key components of i-LAMP are SFP coupon database, water chemistry, and analysis.

Analysis not only includes data analysis for coupons and water chemistry but also impact on reactivity.

5 Draft SE - Section 4.1: Limitations and Conditions Emphasis is on detailed plant specific analysis and age of the BORAL. As written, draft SE diminishes the industrywide and learning components of the program.

4.1.

Limitations and Conditions Based on the staff review of NEI 16-03, Rev. 1, described above, the NRC staff has identified the following limitation on the use of the methodology shown below:

The NRC staff approves the NEI 16-03, Rev. 1, methodology for employing i-LAMP as an alternative monitoring strategy only if the i-LAMP program provides for the licensee to perform a detailed analysis of its SFP and BORAL material considering the parameters described in NEI 16-03 Rev 1. The i-LAMP alternative strategy is unacceptable unless a plant-specific analysis verifies that SFP conditions and BORAL parameters are consistent with those of a sibling SFP or are bounded by those of an older SFPs BORAL. This limitation is imposed to address the discussion in NEI 16-03 Rev.1 of a 2-bin system in which plants without coupons are assumed to be bounded by those with coupons.

6 Draft SE implementation reads like Three observations:

1) Not tied to general i-LAMPs industrywide umbrella

2) To date, no trend is identified for informed sibling identification based on relative importance of different parameters,

3) Trend will be identified by the learning component of i-LAMP SFP A - NO Coupon SFP B - With Coupon Uncertainty in degree of similarity? How similar is consistent?

Identify sibling via plant specific detailed analysis

7 Age of the BORAL - Is that a limiting factor?

To date, age alone in the absence of other degradation drivers is not associated with degradation.

Panels from Zion SFP (~20 years service time)

EPRI and NRC independent analysis under MOU Panels from Operating SFP

(~40 years service time and resided in two SFPs with storage in warehouse in between)

8 Age, vintage, and cumulative neutron and gamma radiation dose - Are these limiting factors for BORAL?

Zion Region 1 Zion Region 2 SFP-2 Installation Year 1994 1994 1997*

Service time (years)

~20

~40**

of panels removed 8

6 2

Blisters 1***

N N

Gross Degradation N

N N

Thickness (in.)

0.101 0.085 0.085 Min. Cert. AD (g 10B/cm2) 0.03 0.023 0.023 Example sample from SFP-2 panels Example samples from Zion panel To date, no variation with service time (age; neutron and gamma dose); type (varying areal densities and thicknesses)

Panels had previous history, in SFP-1

- Wet storage time, does not include dry storage time in between SFPs

- - Only one panel showed a very small blister at the corner Comparison of Panels from Zion SFP vs. SFP-2 Bottom Top Dose and temperature vary with axial location; no trend in actual measured data from panel with 40 years service time

9 Water Chemistry Parameters - Limiting factor for BORAL?

Zion versus SFP-2 Panels: Despite variations in age, service time, water chemistry (especially for B), no significant degradation or difference in material condition. For panels from SFP-2, water chemistry from previous pool is not retrieved -

since panels were almost pristine Zion Zion Zion SFP-2 SFP-2 SFP-2

10 How similar is similar enough? Panel Histories: Case-1 (C-1) versus Sibling-1 (S-1)

Unique panel history - very similar to panel history residing in SFP-2, described in previous presentation Wet-Dry-Wet Old BORAL panels Case-1: ~30 years in-pool service history Sibling-1: ~40 years in-pool service history One BORAL type Case-1: Two boral types Old BORAL (reclaimed from SFP-A), installed in SFP-B in 1997 New BORAL, installed in 1998 New BORAL has higher AD but uses the same AD (lower value based on old BORAL) in CSA Sibling-1 (S-1) Panel History Case-1 (C-1) Panel History -

Coupons from S-1 are coming to this SFP Case 1 has OLDER BORAL but less service time? Can they still use coupons from Sibling 1 based on draft SE language?

11 How similar is similar enough: Water Chemistry for Sibling Pool-1 versus Case - Boron Levels Sibling Pool-1 Boron Levels Case-1 Boron Levels Case-1 Boron levels lower than Sibling Pool-1 Boron levels and more consistent with industry averages - despite differences, can they still use coupons from Sibling-1?

Are these similar enough?

12 How similar is similar enough? - Variations in Areal Density (AD)

For AD, SFPs without coupons are represented by SFPs with coupons

13 How similar is similar enough? - Variations in Installation Year For Installation year, SFPs w/o coupons are represented by SFPs with coupons - two exceptions were discussed separately

14 Current Draft SE versus Proposed Change Further binning and sibling determination will be done when/if a trending parameter(s) is established. Proposed approach maintains industrywide and learning components SFP A - NO Coupon Demonstrate consistent with the data in i-LAMP i-LAMP General Program

15 Proposed Change Plant specific analysis to demonstrate SFP data is consistent with general i-LAMP databases. Further binning and sibling determination will be done when/if a trending parameter is established Distribution of B levels across industry for PWRs SFP specific analysis to demonstrate within i-LAMP Distribution of B level for specific SFP SFP specific analysis to demonstrate within i-LAMP for potential key parameters, such as:

B (PWR)

Cl SO4

16 Draft SE Section 4.1 (Limitations and Conditions)

Current language:

The NRC staff approves the NEI 16-03, Rev. 1, methodology for employing i-LAMP as an alternative monitoring strategy only if the i-LAMP program provides for the licensee to perform a detailed analysis of its SFP and BORAL material considering the parameters described in NEI 16-03 Rev 1. The i-LAMP alternative strategy is unacceptable unless a plant-specific analysis verifies that SFP conditions and BORAL parameters are consistent with those of a sibling SFP or are bounded by those of an older SFPs BORAL. This limitation is imposed to address the discussion in NEI 16-03 Rev.1 of a 2-bin system in which plants without coupons are assumed to be bounded by those with coupons.

Proposed language:

The NRC staff approves the NEI 16-03, Rev. 1, methodology for employing i-LAMP as an alternative monitoring strategy if a plant-specific licensee analysis demonstrates that its SFP conditions and BORAL parameters are represented in the i-LAMP database and that there are no degradation trends identified by the i-LAMP program that are relevant to the licensee's BORAL. If a relevant trend is identified, the licensee shall identify one or more siblings with consistent parameters and will monitor the sibling(s) BORAL performance trends within its corrective action program.

17 Questions?

18 TogetherShaping the Future of Energy

19 Backup Slides

20 Spent Fuel Pool (SFP) Neutron Absorber Material (NAM) Monitoring

1. Coupon Monitoring

Many SFPs have no coupons

Many SFPs have few coupons left

2. In situ Measurements (Existing tool: BADGER)

- Expensive

- SFP logistic issues and dose

- Can be inaccurate and lead to false degradation*

3. Cutting NAM panels from rack modules

- Very expensive

- May lead to rack module damage (left with cells that cant be used)

- Plant and SFP logistic issues and dose

Zion comparative analysis performed blind comparison of in-situ and actual panels, which showed false degradation predicted by in-situ measurements SFPs with neutron absorber materials need a NAM aging management program (AMP)

21 NAM Degradation Mechanisms and Potential Concerns Pit picture with 100x magnification; pit reached absorber material

1. Pitting

2. Blistering Blistering is only applicable to absorber materials with cladding (i.e., BORAL, Maxus, etc.)

For a given neutron absorber material, aging effects in SFPs can be a function of:

1. Type and vintage of the material

2. Time in the SFP

3. SFP water chemistry

4. Temperature

5. Cumulative neutron dose

6. Cumulative gamma dose For BORAL, based on research and data analysis over the past 10 years and >40 years of OE; no significant degradation observed; therefore, no correlation to a given parameter For different materials, significance of parameters vary (i.e., effect of gamma dose for BORAL versus Boraflex)

22 Zion Comparative Analysis Project

23 Zion Comparative Analysis project - Key Findings Zion Panels Zion In-situ Measurements Zion Coupons Coupons represent panels in a conservative manner

1. Good agreement between panel and coupon areal densities

2. No axial height dependence for areal density for panels (radiation and temperature impacts are minimal)

3. Coupons show more pits compared to panels

24 Zion Comparative Analysis project - Key Findings Zion Panels In-situ measurements Zion Coupons One of the key recommendation after Zion was to re-insert coupons into SFP without heat drying to avoid losing remaining coupons across the industry. This approach is now accepted by the NRC and implemented by the industry 0.0270 0.0280 0.0290 0.0300 0.0310 0.0320 0.0330 0.0340 0.0350 0.0360 0.0370 2K21N-02 2K21N-04 2K21N-06 2K21N-08 2K21N-10 2K21N-12 10B Areal Density [g/cm2]

Coupon Name 2K21N Neutron Attenuation AD BADGER AD Nominal AD 4.

In situ (BADGER) measurements underpredict Areal Density Implies false degradation

25 Accelerated Corrosion Project

26 Accelerated Corrosion Test Approach

Place pre-characterized BORAL coupons in test baths representing

PWR and BWR water chemistry

Water chemistry measured regularly

At elevated temperatures (91oC - 196oF)

Compared to typical pool temperature: ~27-38°C (80-100°F)

Evaluate changes in coupon attributes after exposure to accelerated environmental conditions.

Five year test Objectives

Evaluate/demonstrate BORAL in-pool performance for an extended service life

Determine long-term corrosion rate of BORAL

27 Accelerated Corrosion Tests - Key Findings No statistically significant change in Areal Density values for Year 5 coupons No statistically significant change in Areal Density for Year 1-4 coupons either Clad removed coupon Even for clad removed coupons, no statistically significant change in AD over time Considered extending the project beyond 5 years, although coupons are in great condition, corrosion test baths degraded

28 Evaluation of Impact of Blisters and Pits on SFP Reactivity (Consequence Study)

29 Evaluation of the Impact of NAM Blistering and Pitting on SFP Reactivity - Key Findings EPRI report, 3002013119, Evaluation of the Impact of Neutron Absorber Material Blistering and Pitting on Spent Fuel Pool Reactivity, May 2018.

Objectives Based on extensive simulations, pits observed to date have no statistically significant impact on reactivity (need to be >300X larger and in worst location)

Max. pit area from OE to date Threshold for non-negligible impact Perform simulations and analysis to evaluate Impact of pits on reactivity Impact of blisters on reactivity Perform analysis to determine

1. Impact based on operational experience (OE) to date

2. The bounds when impact become non-negligible

30 Evaluation of Panels from an Operating SFP - Key Findings Panels are in very good condition No blisters Despite being considered most susceptible to blisters due to age General flow patterns, scratches but no gross degradation These panels are unique:

1. Age and vintage (considered most susceptible for blistering)

2. Used in two SFPs

3. Storage time in between two pools (dry)

4. Long service time (~40 years)

1. No loss of absorber material

2. Areal density (AD) values higher than minimum certified (AD)

3. No clear dependence to variation in axial heightNo impact of temperature and radiation variations Bottom Top

31 Comparison of Panels from Zion SFP vs. SFP-2 Zion Region 1 Zion Region 2 SFP-2 Installation Year 1994 1994 1997*

Service time (years)

~20

~40**

of panels removed 8

6 2

Blisters 1***

N N

Gross Degradation N

N N

Thickness (in.)

0.101 0.085 0.085 Min. Cert. AD (g 10B/cm2) 0.03 0.023 0.023 Zion Module being removed from pool Panel being removed from SFP-2 Example sample from SFP-2 panels Example samples from Zion panels Panels removed from Zion and SFP-2 were in very good condition:

General flow patterns, scratches but no gross degradation

Panels had previous history, in SFP-1, as shown in Slide 12

- Wet storage time, does not include dry storage time in between SFPs

- - Only one panel showed a very small blister at the corner

32 i-LAMP: Industrywide Global Learning Aging Management Program EPRIs research over the past ~8 years informed establishment of technical basis and implementation plan for i-LAMP Global program - Initial focus is on BORAL NAM specifications (type, vintage)

NAM history (installation and manufacturing years)

SFP water chemistry history NAM performance (coupon monitoring)

Similar NAM Specifications Similar Water Chemistry Similar NAM Vintage SFP With Coupons SFP Without Coupons Sibling Pool Process - If No Coupons Identify sibling(s)

Commitment to i-LAMP for AMP Periodic data updates (learning)

Periodic sibling performance update Siblings

33 i-LAMP Databases EPRI is the owner of these databases. Databases are live and updated as new data comes SFP Water Chemistry pH Conductivity Chloride (Cl) concentration Fluoride (F) concentration Sulfate (SO4) concentration Additionally, for PWRs Boron (B) concentration Sodium (Na) concentration SFPs with Coupon Pool name Rack installation year Rack type (egg crate versus flux trap)

Stainless steel encapsulation or not Coupon unique ID number Coupon analysis year(s), if the same coupon is analyzed multiple times Dimension data (pre-characterization and post-irradiation)

- Height, width, thickness

- Weight

- Areal density values (pre-irradiation and post-irradiation)

- Pit and blister data

- Pictures SFPs w/o Coupon Pool name

Rack installation year

Rack type (egg crate versus flux trap)

Stainless steel encapsulation or not

Dimension data

Height, width, thickness

Weight

Areal density values

34 Two Pilots for Demonstration as Case Studies - Pilot-1 Surrogate Panel History Pilot-1 Panel History Instead of simply using SFP-2 as surrogate, proposed to install extra samples from Surrogate-1 to Pilot-1, which is beneficial for all stakeholders

35 Necessary Elements for i-LAMP Long Term Success i-LAMP data, need, and commitment is global

Maintain existing coupon inventory o Return coupons to SFP after periodic testing Prior typical utility practice was to discard o Transfer coupons to a sibling SFP after decommissioning

Update coupon monitoring data o Provided by utilities to EPRI after periodic testing o EPRI identification of adverse trends

Maintain and update water chemistry data (sent by utilities to EPRI)

Standardization of coupon analysis EPRI report 3002018497, published in August 2022. Report is publicly available

v t e Letter Sequence Request
EPID:L-2022-NTR-0002, (Open)
Initiation Request, Request, Request, Request Acceptance, Acceptance, Acceptance, Acceptance Supplement Administration Meeting Questions 24 April 2023 24 April 2023 Answers 23 May 2023 Results Approval Other: ML24054A079
MONTHYEAR2023-12-19 [Table View]

ML23347A178

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