Text

12-14 NEI EPRI Presentation NRC Public Meeting 16-03 R1
	ML23347A178
Person / Time
Site:	Nuclear Energy Institute
Issue date:	12/13/2023
From:	; Nuclear Energy Institute
To:	Gerond George; Licensing Processes Branch
References
	Download: ML23347A178 (1)
	v • d • e

Industry Comments on Draft NRC Safety Evaluation: NEI 16-03, Revision 1,Guidance for Monitoring of Fixed Neutron Absorbers in Spent Fuel Pools December 14, 2023

Industry Objectives for NEI 16-03, Rev. 1 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.

Objective for Todays Meeting Propose wording for the NRCs draft safety evaluation for NEI 16-03, Rev. 1 that:

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.

Draft Safety Evaluation Report Current language in Limitations and Conditions:

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 Proposed Wording for Limitations and Conditions:

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.

Basis for Revised Wording 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.

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.

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 www.epri.com © 2023 Electric Power Research Institute, Inc. All rights reserved.

Draft SE: i-LAMP Components Section 3.3.1, page 7, line 31: The core of i-LAMP is an SFP coupon database i-LAMP general layout i-LAMP not only relies on coupon database but also has other vital components to be considered an effective monitoring program 2 © 2023 Electric Power Research Institute, Inc. All rights reserved.

Technical Basis for an Effective Aging Management Program Laboratory: Accelerated Corrosion Test (to be published soon 3002023975)

Operating Actual panels, coupons, and in-situ Laboratory Experience: measurements from SFP: Zion comparative Tests Monitoring analysis (3002008196 and 3002008195)

Results*

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

Consequence Experience:

Analysis*** Actual Panel Analysis**

Evaluation of Panels from an Operating SFP (3002018497)

Coupon and in situ

- Panels from Zion & Operating SFP i-LAMP proposal (3002013122) and i-LAMP final report (3002018497)

- - Evaluation of impact of blister and pits on SFP reactivity Work has been published in 7 EPRI reports and > 25 papers To date, no significant degradation; no dependence on one parameter or parameters 3 © 2023 Electric Power Research Institute, Inc. All rights reserved.

Draft SE: i-LAMP Components 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.

Draft SE - Section 4.1: Limitations and Conditions 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.

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.

Draft SE implementation reads like SFP B - With Coupon SFP A - NO Identify sibling via plant specific Uncertainty in degree of Coupon detailed analysis similarity? How similar is consistent?

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,

Age of the BORAL - Is that a limiting factor?

Panels from Operating SFP

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

Panels from Zion SFP (~20 years service time)

EPRI and NRC independent analysis under MOU To date, age alone in the absence of other degradation drivers is not associated with degradation.

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

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

Example samples from Example sample from Service time (years) ~20 ~20 ~40** Zion panel SFP-2 panels

of panels removed 8 6 2 Dose and Blisters 1*** N N temperature Gross Degradation N N N vary with axial location; no Thickness (in.) 0.101 0.085 0.085 trend in actual measured data Min. Cert. AD 0.03 0.023 0.023 from panel with (g 10B/cm2) 40 years service

Panels had previous history, in SFP-1 time

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

- - Only one panel showed a very small blister at the corner To date, no variation with service time (age; neutron and gamma dose); type (varying areal densities and thicknesses) 8 © 2023 Electric Power Research Institute, Inc. All rights reserved.

Water Chemistry Parameters - Limiting factor for BORAL?

Zion Zion Zion SFP-2 SFP-2 SFP-2 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 9

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 (C-1) Panel History -

Coupons from S-1 are

Case-1: Two boral types coming to this SFP

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 has OLDER BORAL but less service time? Can they still use coupons from Sibling 1 based on draft SE language?

How similar is similar enough: Water Chemistry for Sibling Pool-1 versus Case - Boron Levels Are these similar enough?

Case-1 Boron Levels Sibling Pool-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?

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

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 13 © 2023 Electric Power Research Institute, Inc. All rights reserved.

Current Draft SE versus Proposed Change SFP A - NO Demonstrate consistent with the i-LAMP General Program Coupon data in i-LAMP Further binning and sibling determination will be done when/if a trending parameter(s) is established. Proposed approach maintains industrywide and learning components 14 © 2023 Electric Power Research Institute, Inc. All rights reserved.

Proposed Change SFP specific analysis to demonstrate within i-LAMP SFP specific analysis to demonstrate within i-LAMP for potential key parameters, such as:

B (PWR)

Cl

SO4 Distribution of B level for specific SFP Distribution of B levels across industry for PWRs 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 15 © 2023 Electric Power Research Institute, Inc. All rights reserved.

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.

Questions?

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

1. Coupon Monitoring

Many SFPs have no coupons

Many SFPs have few coupons left

Zion comparative analysis

2. In situ Measurements (Existing tool: BADGER) performed blind comparison of

- Expensive in-situ and actual panels, which showed false degradation

- SFP logistic issues and dose predicted by in-situ

- Can be inaccurate and lead to false degradation* measurements

3. Cutting NAM panels from rack modules

- Very expensive

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

NAM Degradation Mechanisms and Potential Concerns

1. Pitting 2. Blistering 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 different materials, Pit picture with 100x Blistering is only applicable to significance of parameters vary magnification; pit reached absorber materials with cladding (i.e., effect of gamma dose for absorber material (i.e., BORAL, Maxus, etc.) BORAL versus Boraflex)

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 21 © 2023 Electric Power Research Institute, Inc. All rights reserved.

Zion Comparative Analysis project - Key Findings Zion Panels Zion Zion In-situ 1. Good agreement between panel Coupons Measurements and coupon areal densities

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

Zion Comparative Analysis project - Key Findings Zion Panels 2K21N Neutron Attenuation AD BADGER AD Nominal AD 0.0370 Zion In-situ 0.0360

4. In situ (BADGER) measurements Densi ty [g/cm2 ]

0.0350 Coupons measurements 0.0340 underpredict Areal Density 0.0330 0.0320 Implies false degradation 0.0310 10 B Areal 0.0300 0.0290 0.0280 0.0270 2K21N-02 2K21N-04 2K21N-06 2K21N-08 2K21N-10 2K21N-12 Coupon Name 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 24 © 2023 Electric Power Research Institute, Inc. All rights reserved.

Accelerated Corrosion Test Objectives

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

Determine long-term corrosion rate of BORAL 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.

Accelerated Corrosion Tests - Key Findings Clad removed coupon

No statistically significant change in Areal Density values for Year 5

Even for clad removed coupons, no coupons

No statistically statistically significant change in AD significant change over time in Areal Density

Considered extending the project for Year 1-4 beyond 5 years, although coupons are coupons either in great condition, corrosion test baths degraded 27 © 2023 Electric Power Research Institute, Inc. All rights reserved.

Evaluation of the Impact of NAM Blistering and Pitting on SFP Reactivity - Key Findings Objectives Threshold for non-Perform simulations and negligible impact 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 Max. pit area from

2. The bounds when impact OE to date become non-negligible EPRI report, 3002013119, Evaluation of the Based on extensive simulations, pits observed to Impact of Neutron Absorber Material Blistering and Pitting on Spent Fuel Pool Reactivity, May date have no statistically significant impact on 2018. reactivity (need to be >300X larger and in worst location) 29 © 2023 Electric Power Research Institute, Inc. All rights reserved.

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)

1. No loss of absorber material

2. Used in two SFPs

2. Areal density (AD) values higher

3. Storage time in between two pools than minimum certified (AD)

(dry)

3. No clear dependence to

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 ~20 ~40**

of panels removed 8 6 2 Blisters 1*** N N Gross Degradation N N N Zion Module being Thickness (in.) 0.101 0.085 0.085 removed from pool Min. Cert. AD 0.03 0.023 0.023 (g 10B/cm2)

Example samples from Zion panels

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 Panels removed from Zion and SFP-2 were in very good condition:

i-LAMP: Industrywide Global Learning Aging Management Program Global program - Initial focus is on BORAL Sibling Pool Process - If No Coupons NAM specifications (type, vintage) Identify sibling(s)

NAM history (installation and manufacturing years) Commitment to i-LAMP for AMP SFP water chemistry history Periodic data updates (learning)

NAM performance (coupon monitoring) Periodic sibling performance update Siblings Similar NAM Specifications Similar Water Chemistry Similar NAM Vintage SFP With Coupons SFP Without Coupons EPRIs research over the past ~8 years informed establishment of technical basis and implementation plan for i-LAMP 32 © 2023 Electric Power Research Institute, Inc. All rights reserved.

i-LAMP Databases SFP Water Chemistry SFPs with Coupon SFPs w/o Coupon pH Pool name Pool name Conductivity Rack installation year

Rack installation year Chloride (Cl) concentration Rack type (egg crate versus flux trap)

Rack type (egg crate versus flux trap)

Fluoride (F) concentration Stainless steel encapsulation or not

Stainless steel encapsulation or not Sulfate (SO4) concentration Coupon unique ID number

Dimension data Additionally, for PWRs Coupon analysis year(s), if the same

Height, width, thickness Boron (B) concentration coupon is analyzed multiple times

Weight Sodium (Na) concentration Dimension data (pre-

Areal density values characterization and post-irradiation)

- Height, width, thickness

- Weight

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

- Pit and blister data

Two Pilots for Demonstration as Case Studies - Pilot-1 Surrogate Panel History Instead of simply using SFP-2 as surrogate, proposed to install extra samples from Surrogate-1 to Pilot-1, which is Pilot-1 Panel History beneficial for all stakeholders 34 © 2023 Electric Power Research Institute, Inc. All rights reserved.

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)

ML23347A178

Text

Navigation menu

Search