ML23291A013

Draft Safety Evaluation NEI 16-03 Revision 1

ML23291A013
Person / Time
Site:	Nuclear Energy Institute, 99902028
Issue date:	12/08/2023
From:	Leslie Fields Licensing Processes Branch
To:	Gerond George Licensing Processes Branch
Shared Package
ML23291A288	List: ML23291A013
References
NEI 16-03, Rev 1, EPID L-2022-NTR-0002
Download: ML23291A013 (1)

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OFFICIAL USE ONLY OFFICIAL USE ONLY THIS IS A DRAFT DOCUMENT UNDER NEI REVIEW FOR COMMENT. LINE NUMBERS HAVE BEEN ADDED TO EASILY IDENTIFY WHERE COMMENTS ARE BEING MADE.

LINE NUMBERS WILL BE REMOVED IN THE FINAL DRAFT.

OFFICIAL USE ONLY OFFICIAL USE ONLY DRAFT SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION 1

FOR NUCLEAR ENERGY INSTITUTE DOCUMENT, 2

NEI 16-03, REVISION 1, GUIDANCE FOR MONITORING OF 3

FIXED NEUTRON ABSORBERS IN SPENT FUEL POOLS 4

PROJECT NO. 689; DOCKET NO. 99902028; EPID L-2022-NTR-0002 5

6 7

OFFICIAL USE ONLY OFFICIAL USE ONLY 1

Table of Contents 2

1.0 INTRODUCTION

........................................................................................................... 3 2.0 REGULATORY EVALUTION........................................................................................ 4 2.1 Applicability of NRC Regulatory Requirements and Guidance..................................... 5 2.1.1 NRC Regulations......................................................................................................... 6 2.1.2 General Design Criteria................................................................................................ 7 2.1.3 NRC Guidance Documents.......................................................................................... 8

3.0 TECHNICAL EVALUATION

.......................................................................................... 9 3.1 Guidance for Developing a Neutron Absorbing Monitoring Program........................... 10 3.2 Coupon Testing Program............................................................................................. 11 3.2.1 Overview of NEI 16-03, Revision 1.............................................................................. 12 3.2.2 NRC Staffs Evaluation of the Coupon Testing Program.............................................. 13 3.3 Industrywide Learning Aging Management Program................................................... 14 3.3.1 Overview of NEI 16-03, Revision 1.............................................................................. 15 3.3.2. NRC Staffs Evaluation of the Industrywide Learning Aging Management Program.. 16 3.4.

In-Situ Measurement Program................................................................................... 17 3.4.1. Overview of NEI 16-03, Revision 1............................................................................ 18 3.4.2. NRC Staffs Evaluation of In-Situ Measurement Program.......................................... 19 3.5.

Evaluating Neutron Absorber Test Results................................................................ 20 3.5.1. Overview of NEI 16-03, Revision 1............................................................................ 21 4.0 CONDITIONS, LIMITATIONS, AND/OR ACTION ITEMS........................................... 22

5.0 CONCLUSION

S.......................................................................................................... 23

6.0 REFERENCES

............................................................................................................ 24 25 26 27

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1.0 INTRODUCTION

1 2

By letter dated August 19, 2022 (Ref. 1), as supplemented by letters (Ref. 4) dated October 12, 3

2022, December 15, 2022, May 23, 2023, and August 24, 2023, the Nuclear Energy Institute 4

(NEI) submitted proposed methodology document NEI 16-03, Revision (Rev.) 1, Guidance for 5

Monitoring of Fixed Neutron Absorbers in Spent Fuel Pools (Ref. 2), on behalf of its members 6

for U.S. Nuclear Regulatory Commission (NRC) review and endorsement. NEI 16-03, Rev. 1 7

includes Electric Power Research Institutes (EPRIs) Technical Report 3002018497, 8

Industrywide Learning Aging Management Program (i-LAMP): Global Neutron Absorber 9

Material Monitoring Program for Spent Fuel Pools (Ref. 3) dated August 2022, as an alternative 10 monitoring approach.

11 12 The purpose of NEIs document is to provide guidance for licensees to develop an acceptable 13 fixed neutron absorber monitoring program in spent fuel pools (SFPs) as a means to 14 demonstrate compliance with applicable regulations in Section 50.68 of Title 10 of the Code of 15 Federal Regulations (10 CFR), Criticality Accident Requirements, Appendix A to 10 CFR 16 Part 50, General Design Criterion (GDC) 61, Fuel Storage and Handling and Radioactivity 17 Control, and Appendix A to 10 CFR Part 50, GDC 62,Prevention of Criticality in Fuel Storage 18 and Handling, with respect to neutron absorbing materials (NAMs). Although NEI requested the 19 NRC staff to endorse NEI 16-03, Rev. 1, the NRC staff is not proposing to issue a regulatory 20 guide to endorse NEI 16-03. Instead, as stated in this Safety Evaluation (SE), the NRC staff is 21 treating NEI 16-03, Rev. 1, as a topical report, and as described below, the NRC staff has 22 determined that NEI 16-03, Rev. 1 is acceptable, with the limitation described below, for 23 referencing in a license amendment request (LAR) that includes the information described 24 below in Section 4.0 of this SE.

25 26 2.0 REGULATORY EVALUTION 27 28 The effectiveness of the NAM installed in SFP storage racks ensures that the effective neutron 29 multiplication factor (keff) does not exceed the maximum value derived from the criticality 30 analysis of record (AOR) and other licensing basis documents. The AOR is the basis, in part, for 31 demonstrating compliance with plant technical specifications and with applicable NRC 32 regulations. Degradation or deformation of the credited NAM may reduce safety margin and 33 potentially challenge the subcriticality requirement. NAMs utilized in SFP racks exposed to 34 treated water or treated borated water may be susceptible to reduction of neutron absorbing 35 capacity, changes in dimension, and/or loss of material that increases keff. A licensee 36 implements a monitoring program to ensure that degradation of the NAM used in SFPs, which 37 could compromise the ability of the NAM to perform its safety function as presumed in the AOR, 38 will be detected.

39 40

OFFICIAL USE ONLY OFFICIAL USE ONLY 2.1 Applicability of NRC Regulatory Requirements and Guidance 1

2 NRCs regulatory requirements and the corresponding staff review criteria and guidance for 3

NAM monitoring programs are identified in the following subsections.

4 2.1.1 NRC Regulations 5

The regulations in 10 CFR 50.68(b)(4), Criticality accident requirements, indicates that if the 6

licensee does not credit soluble boron in the SFP criticality AOR, the keff of the SFP storage 7

racks must not exceed 0.95 at a 95 percent probability, 95 percent confidence level, if flooded 8

with unborated water. If the licensee does take credit for soluble boron, the keff of the SFP 9

storage racks must not exceed 0.95 at a 95 percent probability, 95 percent confidence level, if 10 flooded with borated water; and if flooded with unborated water, the keff must remain below 1.0 11 at a 95 percent probability, 95 percent confidence level.

12 2.1.2 General Design Criteria 13 GDC 61, Fuel storage and handling and radioactivity control, states, in part, that 14 The fuel storage and handling, radioactive waste, and other systems which may 15 contain radioactivity shall be designed to assure adequate safety under normal and 16 postulated accident conditions. These systems shall be designed (1) with a capability 17 to permit appropriate periodic inspection and testing of components important to 18 safety[.]

19 20 GDC 62, Prevention of Criticality in Fuel Storage and Handling, states that 21 Criticality in the fuel storage and handling system shall be prevented by physical 22 systems or processes, preferably by use of geometrically safe configurations.

23 2.1.3 NRC Guidance Documents 24 NUREG-0800, Standard Review Plan [(SRP)], Section 9.1.1, Rev. 3, Criticality 25 Safety of Fresh and Spent Fuel Storage and Handling (Ref. 7) provides guidance 26 regarding the acceptance criteria and review procedures to ensure that the proposed 27 changes satisfy the requirements in 10 CFR 50.68.

28 29 NUREG-0800, Standard Review Plan, Section 9.1.2, Rev. 4, New and Spent Fuel 30 Storage (Ref. 8) provides guidance regarding the acceptance criteria and review 31 procedures to ensure that the proposed changes satisfy the requirements in 32 10 CFR 50.68.

33 34 NUREG-1801, Generic Aging Lessons Learned (GALL) Report, Rev. 2 (Ref. 9) 35 provides guidance on what constitutes an acceptable monitoring program for NAMs 36 providing criticality control in the SFP.

37 38

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3.0 TECHNICAL EVALUATION

1 This technical evaluation section documents the NRC staff's evaluation of the NEI 16-03, Rev. 1 2

against the relevant criteria identified in Section 2.0 of this SE.

3 3.1 Guidance for Developing a Neutron Absorbing Monitoring Program 4

NEI 16-03, Rev. 1 provides guidance for developing a NAM monitoring program for NAM in the 5

SFP. The purpose of a NAM monitoring program is to verify that the NAM installed in SFPs 6

continues to provide the criticality control relied upon in the AOR and help to maintain the 7

subcriticality margin in accordance with 10 CFR 50.68 requirements. NEI 16-03, Rev. 1 provides 8

an approach for developing a NAM monitoring program that relies on periodic inspection, 9

testing, monitoring, and analysis of the NAM. To accomplish this purpose, the NEI 16-03, Rev. 1 10 states that a monitoring program must be capable of identifying unanticipated changes in the 11 absorber material and determining whether anticipated changes can be verified. NEI 16-03, 12 Rev. 1 describes a method that uses coupon testing, in-situ measurement, and/or an i-LAMP as 13 a means to monitor potential changes in characteristics of the NAM.

14 The NRC staff reviewed NEI 16-03, Rev. 1 to determine whether the approach it describes will 15 result in an acceptable monitoring program, i.e., one that has the ability to ensure that potential 16 degradation of SFP NAM will be detected, monitored, and mitigated. As set forth below, the 17 NRC staff determined that an appropriate combination of the three methods listed above 18 (coupon testing, in-situ measurement, and/or i-LAMP) can comprise an effective NAM 19 monitoring program. During the course of NRC staffs review, several topics were identified that 20 warranted clarification. The NRC staff issued a request for additional information (Ref. 10) and 21 NEI provided clarifying responses and modified NEI 16-03, Rev. 1 as appropriate.

22 3.2 Coupon Testing Program 23 3.2.1 Overview of NEI 16-03, Revision 1 24 NEI 16-03, Rev. 1 describes the use of a coupon testing program as the preferred method for a 25 NAM monitoring program. This method employs small sections (coupons) of the same NAM 26 installed in the SFP, which are attached to a structure (coupon tree) in the SFP. The coupon 27 tree is placed near freshly discharged fuel assemblies in an attempt to accelerate potential 28 degradation mechanisms.

29 30 31

OFFICIAL USE ONLY OFFICIAL USE ONLY NEI 16-03, Rev. 1 provides the following criteria for an acceptable coupon program:

1 2

The number of coupons needs to be adequate to allow for sampling at intervals for 3

the intended life of the absorbers.

4 The sampling intervals are based on the expected rate of material change.

5 Performance of coupon testing includes:

6 7

Basic testing defined as visual observations, dimensional measurements, and 8

weight analysis, and 9

10 Full testing defined as density measurements, Boron-10 (10B) areal density (AD) 11 measurements, microscopic analysis, and characterization of changes, in addition to 12 the basic testing parameters.

13 14 NEI 16-03, Rev. 1 states that the coupons will be located in the SFP such that their exposure to 15 parameters controlling change mechanisms is conservative or similar to the in-service neutron 16 absorbers. For neutron attenuation testing, NEI 16-03, Rev. 1 provides acceptance criteria 17 for the NAM depending on if there is, or is not, an anticipated loss of 10B AD. The acceptable 18 result for NAMs with expected 10B AD loss is the 10B AD of the test coupon is greater than the 19 10B AD assumed in the licensees SFP criticality AOR. For NAM without an expected loss of 20 10B AD, the acceptable result is the 10B AD of the test coupon is equal to the original 10B AD 21 of the coupon (within measurement uncertainty).

22 23 In regard to sampling frequency, NEI 16-03, Rev. 1 states that the acceptable initial sampling 24 interval for testing of new material (i.e., with a limited, or no, operating history) is up to 5 years, 25 with subsequent intervals up to 10 years. For those materials that have well-documented 26 operating experience, they do not have a history of degradation or degradation mechanisms, 27 and information on stability of the material condition is well developed. NEI 16-03, Rev. 1 states 28 that initial and subsequent test intervals up to 10 years are acceptable. NEI 16-03, Rev. 1 states 29 that for materials with known degradation mechanisms, or a history of known degradation (e.g.,

30 Boraflex, Carborundum, Tetrabor, etc.), the acceptable interval for neutron attenuation testing is 31 at least once every five years. In addition, NEI 16-03, Rev. 1 includes neutron attenuation 32 testing in the full testing approach for any NAMs used, as a component of a satisfactory NAM 33 monitoring program.

34 3.2.2 NRC Staffs Evaluation of the Coupon Testing Program 35 The NRC staff has evaluated NEI 16-03, Rev. 1 for the basic and full portions of a coupon 36 testing program. The basic portion of the testing includes methods to monitor the physical 37 condition of the NAM so that signs of potential degradation may be observed. The full portion of 38 the testing includes neutron attenuation testing for all NAMs that are credited in the SFP 39 criticality analysis, which will allow the licensee to detect a potential loss in 10B AD. The staff 40 finds the coupon testing program to be acceptable because it includes measurements of 10B AD 41 and of dimensional changes in the material that can impact the ability of the NAM to perform its 42 function as assumed in the licensees SFP criticality AOR.

43 44

OFFICIAL USE ONLY OFFICIAL USE ONLY The NRC staff also determined the acceptance criteria for the coupon testing program provided 1

in NEI 16-03, Rev.1 is acceptable, as follows. The acceptance criteria are adequate to establish 2

that the presumptions regarding the AD of the NAM in the licensees SFP criticality AOR will be 3

maintained, because the acceptance criteria show that the material is either not losing 10B AD 4

(for materials not expected to lose 10B AD), or the 10B AD is still above the 10B AD presumed in 5

the licensees SFP criticality AOR (for NAM anticipated to lose 10B AD). In addition, the NRC 6

staff recognizes that if a coupon being tested approaches the 10B AD value used in the 7

licensees SFP criticality AOR, the licensee would likely need to perform further evaluations 8

and/or take additional corrective actions to conclude that the in-service NAM will not degrade 9

below the 10B AD presumed in the licensees SFP criticality AOR. Provisions for additional 10 corrective actions that may be necessary are discussed in Section 2.4, Evaluating Neutron 11 Absorber Test Results, of NEI 16-03, Rev. 1, and NRC staffs evaluation is discussed in 12 Section 3.5 of this SE.

13 14 NEI 16-03, Rev. 1 also states that coupons may be re-inserted into the SFP after non-15 destructive examination and analysis as long as the coupons are not subjected to heat drying 16 which may cause mechanical damage. The NRC staff understands that the re-installation of 17 coupons may be valuable for licensees that have a limited number of coupons remaining. As 18 stated previously, coupon testing is the preferred method for NAM monitoring and efforts to 19 maintain the coupon inventory are acceptable if the reinserted coupons will continue to yield 20 valid data.

21 3.3 Industrywide Learning Aging Management Program 22 3.3.1 Overview of NEI 16-03, Revision 1 23 The primary difference between NEI 16-03, Rev. 0 and NEI 16-03 Rev. 1 is the addition of 24 i-LAMP as an alternative monitoring option for BORAL plants that do not have surveillance 25 coupons in their SFP. The objective of i-LAMP is to provide access to surrogate or sibling pool 26 data for plants that do not have a coupon monitoring program. The 27 i-LAMP approach is not intended to serve as a replacement for a coupon monitoring program for 28 SFPs with coupons.

29 30 The core of i-LAMP is an SFP coupon database. EPRI compiled data from existing coupon test 31 reports and continues to add data as new test results become available.

32 33

OFFICIAL USE ONLY OFFICIAL USE ONLY NEI 16-03, Rev. 1 states that the following data is being collected from plants with BORAL 1

coupon monitoring programs:

2 3

Pool name 4

Rack installation year 5

Rack type (egg crate versus flux trap) 6 Stainless steel encapsulation or not 7

Coupon unique identification (ID) number 8

Coupon analysis year(s), if the same coupon is analyzed multiple times 9

Dimension data (pre-characterization and post-irradiation) 10 11

- Height, width, thickness 12

- Weight 13

- Areal density values (pre-characterization and post-irradiation) 14

- Pit and blister data 15 16 To participate in i-LAMP and leverage surrogate test results for an SFP, a facility that does not 17 have a BORAL coupon monitoring program identifies a sibling plant or plants in the existing 18 database.

19 20 The essential parameters needed to identify an appropriate sibling plant is listed below:

21 22 Similarity of BORAL characteristics 23 24

- Areal density values 25

- Manufacturing and installation years 26

- Thickness 27 28 Similarity of water chemistry data between SFPs 29 30

- Boron levels 31

- Chlorine, Fluorine, Sulfate levels 32

- Other chemistry parameters 33 34 NEI 16-03 Rev. 1 calls for licensees to review i-LAMP data at least every 5 years to confirm the 35 continued acceptable performance of sibling pool BORAL.

36 37 Acceptance Criteria are described as follows:

38 39 The sibling pool BORAL material is represented in the i-LAMP database.

40 Representation is determined using the parameters described above including 41 material age, areal density, and SFP water chemistry.

42 43 Applicable surrogate data has been updated with new operating experience within the 44 last 10 years, unless older data remains bounding for the sibling pool.

45 46 Applicable surrogate data does not indicate unanticipated changes are occurring.

47 48 Applicable surrogate data confirms that there is no loss of 10B within the 49 measurement uncertainty.

50

OFFICIAL USE ONLY OFFICIAL USE ONLY NEI 16-03 Rev. 1 states that based on major research projects conducted by EPRI and data 1

collected from the industry, there are no known degradation mechanisms that have resulted in 2

loss of 10B in BORAL. Because of this, NEI 16-03, Rev. 1 proposes a 2 bin approach which 3

separates plants into those with coupons and those without coupons. NEI 16-03, Rev. 1 4

proposes that plants without coupons are bounded by the collective database of plants with 5

coupons and therefore do not need to perform a detailed analysis to confirm that they are 6

bounded by a sibling plant or plants. The NRC staffs evaluation of this concept is provided 7

below.

8 3.3.2. NRC Staffs Evaluation of the Industrywide Learning Aging Management Program 9

The NRC staff has evaluated the proposal in NEI 16-03, Rev. 1, for the implementation of i-10 LAMP surrogate test data for BORAL plants without a coupon monitoring program. The staff 11 finds that the guidance provides adequate detail with respect to the essential parameters 12 needed to identify a sibling plant. Specifically, the manufacture date, areal density, service life, 13 physical thickness of the BORAL, and its SFP environment including chemistry should be 14 consistent with or bounded by the characteristics of the BORAL and the service environment in 15 a sibling plant in the existing database.

16 17 In addition, the staff finds that the acceptance criteria and surveillance intervals described in 18 NEI 16-03 Rev. 1 conform to the NRC guidance in the GALL Report, Rev. 2. The acceptance 19 criteria provide reasonable assurance that the assumptions regarding the AD of the NAM in the 20 licensees SFP criticality AOR will be maintained, because the acceptance criteria show that the 21 material not losing 10B AD and is still above the 10B AD assumed in the licensees SFP criticality 22 AOR.

23 24 With respect to the concept of a 2 bin approach, the staff finds that NEI 16-03 Rev. 1 25 represents an overly simplistic approach. While it may be true that the data collected in i-LAMP 26 to date anecdotally bounds all operating SFPs in the United States, the NRC staff is approving 27 use of the i-LAMP approach only for a SFP for which the i-LAMP data bounds the physical 28 characteristics of the BORAL and environmental conditions in the specific SFP. A licensee 29 seeking to reference NEI 16-03, Rev. 1 in an application will need to verify in its application that 30 such is the case. Any licensee that intends to employ i-LAMP as an alternative monitoring 31 strategy should perform a detailed analysis of their SFP and BORAL material considering the 32 parameters described in NEI 16-03 Rev 1. Failure to perform plant-specific analysis to verify 33 that parameters are consistent with a sibling SFP, or bounded by an older SFPs BORAL, 34 constitutes inappropriate application of i-LAMP as an alternative monitoring strategy. This will be 35 addressed in Section 4.0, Limitations and Conditions of this safety evaluation.

36 37 Should a new or different degradation mechanism that causes a loss of 10B in BORAL be 38 discovered, NEI 16-03, Rev. 1, calls for that information to be entered into each affected sites 39 corrective action program. This may include development a coupon monitoring program, or use 40 of in-situ monitoring. If the sibling plant data shows a loss of 10B, then the licensee needs to 41 assume that its plant is also losing 10B and develop another means to monitor its NAM.

42

OFFICIAL USE ONLY OFFICIAL USE ONLY 3.4.

In-Situ Measurement Program 1

3.4.1. Overview of NEI 16-03, Revision 1 2

NEI 16-03, Rev. 1 states that in-situ measurement is another method that can be used to 3

confirm 10B AD of NAM. It further states that this method can be used to supplement coupon 4

monitoring to extend the coupon testing interval, permit greater reliance on basic testing, or in 5

lieu of coupon testing for plants that may no longer have coupons in the SFP. It also states that 6

in-situ measurement can be used if surrogate data in i-LAMP may not be bounding of a plants 7

SFP and NAM parameters.

8 9

The NEI 16-03, Rev. 1 states that all in-situ measurement campaigns are to be performed at an 10 acceptable interval and on an adequate number of panels. NEI 16-03, Rev. 1 gives two options 11 for determining what constitutes an adequate number of panels. The first option uses the 12 methodology of NUREG-6698, Guide for Validation of Nuclear Criticality Safety Calculational 13 Methodology (Ref. 10), to measure a minimum of 59 panels to provide 95/95 confidence limits.

14 The second option selects the panels with the greatest exposure (top 5%) to parameters that 15 influence degradation (e.g., neutron fluence, temperature, time). The number of panels selected 16 from those with the greatest exposure for testing will be no less than one percent of the total 17 panels in the SFP, although more panels can be tested from other areas of the SFP to gain a 18 more representative sampling. NEI 16-03, Rev. 1 also states sources of uncertainty in the in-situ 19 measurement will be identified and quantified.

20 21 The sampling interval will be based upon the NAM credited in the SFP. New materials with 22 minimal operating experience will have an initial test interval that does not exceed 5 years, with 23 subsequent intervals up to 10 years (with appropriate operating experience). For materials with 24 known histories of degradation and known degradation mechanisms, test intervals do not 25 exceed 5 years. For other materials that do not have known histories of degradation or known 26 degradation mechanisms test intervals will not exceed 10 years. NEI 16-03, Rev. 1 also states 27 that if used in conjunction with a coupon monitoring program, the in-situ sampling interval can 28 be longer.

29 30 NEI 16-03, Rev. 1 also provides acceptance criteria for in-situ measurements. It states that for 31 NAMs that do not have potential degradation mechanisms for loss of 10B AD, results of the 32 in-situ measurements are acceptable if the nominal measured 10B AD is greater than or equal 33 to the value assumed in the licensees criticality AOR (within measurement uncertainties). For 34 materials that have potential degradation mechanisms that result in loss of 10B AD, results are 35 considered acceptable if the nominal measured 10B AD minus measurement uncertainty is 36 greater than the 10B AD used in the licensees criticality AOR.

37 38 3.4.2. NRC Staffs Evaluation of In-Situ Measurement Program 39 40 The NRC staff has reviewed the NEI 16-03, Rev. 1 method for performing in-situ measurement 41 testing and finds it to be acceptable, because it allows for detection of degradation mechanisms, 42

OFFICIAL USE ONLY OFFICIAL USE ONLY potential loss of neutron absorption capacity (e.g., loss of 10B), and ensures the NAM will 1

continue to provide the criticality control relied upon in the AOR. The NRC staff reviewed the 2

methodology recommended for determining the number of panels that may be selected for 3

in-situ inspection and finds it to be acceptable because it is based in part on guidance provided 4

in NUREG-6698, or on selecting panels that have experienced the greatest exposure to the 5

SFP environment. The NRC staff also finds that depending on the population of NAM panels in 6

the SFP, a licensee may need to measure more than the minimum of 59 panels to produce 7

95/95 confidence limits. The method used for selecting the panels for in-situ testing will be used 8

to obtain data that is bounding or representative of the entire NAM in the SFP.

9 10 In addition, the NRC staff has determined that the proposed testing intervals (intervals not to 11 exceed 10 years for materials with no known history of degradation/degradation mechanisms, 12 and 5 years for materials with a known history of degradation/degradation mechanisms or for 13 new materials (i.e., no operating history)) are acceptable and consistent with NRC guidance in 14 the GALL Report, Rev. 2. Regardless of how the licensee uses the in-situ monitoring program 15 (e.g., in conjunction with coupons, without a coupon program, or other reasons as described in 16 NEI 16-03, Rev. 1), NEI 16-03, Rev. 1 is acceptable only if neutron attenuation is performed on 17 the intervals as described in the in-situ methodology. The statement in NEI 16-03, Rev. 1 that 18 the in-situ sampling interval can be longer if used in conjunction with a coupon program does 19 not obviate the need to perform neutron attenuation testing on intervals not to exceed 5 or 10 20 years (depending on the NAM used and associated operating experience).

21 22 In addition, sources of uncertainty can greatly impact results and confidence in the data 23 collected, especially as it relates to the subcriticality margin. Accordingly, the NRC staff finds the 24 program to be acceptable if it includes provisions to identify and evaluate sources of uncertainty 25 in order to assess the reliability of the instruments and methodology used to the collect the data.

26 3.5.

Evaluating Neutron Absorber Test Results 27 3.5.1. Overview of NEI 16-03, Revision 1 28 NEI 16-03, Rev. 1 states that the test results from neutron absorber monitoring may fall within 29 the following categories:

30 31

1) Confirmation that no material changes are occurring, 32 33

2) Confirmation that anticipated changes are occurring, and/or 34 35

3) Identification that unanticipated changes are occurring.

36 37 Furthermore, NEI 16-03, Rev. 1 states that the testing results, and/or surrogate i-LAMP data, 38 will be compared to the AOR input (i.e., 10B AD assumed in criticality AOR). If there are no 39 material changes, or if anticipated changes are occurring, then the proposed program indicates 40 that the licensee can conclude that the material continues to be adequately represented in the 41 AOR.

42

OFFICIAL USE ONLY OFFICIAL USE ONLY NEI 16-03, Rev. 1 also describes the additional actions that may be necessary when 1

unanticipated changes in the NAM are identified. It states that there are certain technical 2

evaluations that may be necessary in addition to any required regulatory or licensing processes.

3 The technical evaluations include one to determine if an unanticipated change in NAM may 4

result in a loss of 10B AD. Any potential impacts of a loss of 10B AD on the SFP criticality AOR 5

will be evaluated and addressed through licensee processes. In addition, the results of 6

monitoring and testing are to be evaluated and trended, regardless of potential impact on the 7

SFP criticality AOR. If an unanticipated change does not appear to result in the loss of 10B AD, 8

the change will still be evaluated for impacts on the SFP criticality AOR. The effects on the SFP 9

criticality AOR due to a potential dimensional change of the NAM, or other material in the SFP, 10 are evaluated and addressed in accordance with licensee processes.

11 12 3.5.2. NRC Staffs Evaluation of Neutron Absorber Test Results 13 14 The NRC staff has reviewed the actions described in NEI 16-03 Rev. 1 for when potential 15 degradation is detected in the neutron absorbing material as potential degradation of the NAM 16 may impact 10B AD presumptions in the SFP criticality AOR. The NRC staff finds the actions 17 described in the NEIs document acceptable because they will be able to identify anticipated, 18 and unanticipated changes to provide information that will allow a licensee to determine whether 19 the neutron absorbing material is performing its safety function as credited in the AOR.

20 21 The NRC staff has also determined that it is necessary to evaluate and trend the results of 22 10B AD measurements from neutron attenuation testing in the NAM as described in NEI 16-03, 23 Rev.1. The NRC staff finds the methods to trend data acceptable because they will provide 24 information regarding the potential degradation mechanism(s) and rate for the NAM in the SFP.

25 This information will also help the licensee determine whether the 10B AD of the NAM will not 26 decrease below the value assumed in the SFP criticality AOR between the specified test 27 intervals for neutron attenuation testing. In addition, these data can identify previously 28 un-evaluated degradation mechanisms that may have an impact on the SFP criticality AOR.

29 30 The actions described above ensure, in part, that the ability of the NAM to provide the criticality 31 control relied upon in the AOR, is maintained.

32 33 3.6.

NRC Technical Evaluation Conclusion 34 35 As summarized below, the NRC staff has determined that the NAM monitoring program 36 described in NEI 16-03, Rev. 1 is acceptable because it includes neutron attenuation testing at 37 acceptable intervals or relies on testing from a surrogate i-LAMP plant that is acceptable if the 38 surrogate plant SFP and NAM conditions and parameters bound those of the licensees plant.

39 More specifically, the NRC staff finds the interval for inspection and testing acceptable because 40 the frequency is determined to be based on the neutron absorbing material credited and the 41 operational history of that material. Further, depending on the material used, the interval for 42 neutron attenuation testing will not exceed 5 years (for materials with a history of known 43 degradation or a known degradation mechanism, and new materials), or 10 years (for other 44 materials that do not have a history of degradation, or a known degradation mechanism). Such 45

OFFICIAL USE ONLY OFFICIAL USE ONLY testing intervals are adequate to detect degradation of NAM before such degradation has the 1

potential to affect criticality safety. Periodic neutron attenuation testing, and the intervals 2

described in NEI 16-03 are consistent with NRC guidance (i.e., the GALL Report, Rev. 2).

3 Licensees will likely need to request site-specific NRC review and approval to extend the 4

interval of any neutron attenuation testing past the approved intervals, as described in 5

NEI 16-03, Rev. 1.

6 7

In addition, the NRC staff finds the proposed program acceptable insofar as it calls for the 8

inclusion of the measurement uncertainty in a determination whether the 10B AD value derived 9

from the program is lower than the presumed value in the SFP criticality AOR. If a given test 10 result shows a 10B AD value lower than the value presumed in the SFP criticality AOR, the 11 program provides for the appropriate corrective actions in accordance with licensee programs 12 and processes.

13 14 Based on the foregoing, the NRC staff has determined that NEI 16-03, Rev.1 is acceptable for 15 referencing in a LAR requesting approval of a NAM monitoring program.

16 17 4.0 CONDITIONS, LIMITATIONS, AND/OR ACTION ITEMS 18 Limitations and Conditions are additional restrictions imposed by the NRC staff to further 19 define the scope of applicability of NEI 16-03 Rev. 1 and identify any additional actions that will 20 need to be addressed to support NRC staffs review of a request associated with this NEIs 21 document.

22 23 4.1.

Limitations and Conditions 24 25 Based on the staff review of NEI 16-03, Rev. 1, described above, the NRC staff has identified 26 the following limitation on the use of the methodology shown below:

27 28 The NRC staff approves the NEI 16-03, Rev. 1, methodology for employing i-LAMP as an 29 alternative monitoring strategy only if the i-LAMP program provides for the licensee to perform a 30 detailed analysis of its SFP and BORAL material considering the parameters described in 31 NEI 16-03 Rev 1. The i-LAMP alternative strategy is unacceptable unless a plant-specific 32 analysis verifies that SFP conditions and BORAL parameters are consistent with those of a 33 sibling SFP or are bounded by those of an older SFPs BORAL. This limitation is imposed to 34 address the discussion in NEI 16-03 Rev.1 of a 2-bin system in which plants without coupons 35 are assumed to be bounded by those with coupons.

36 37

OFFICIAL USE ONLY OFFICIAL USE ONLY

5.0 CONCLUSION

S 1

2 The NRC staff has reviewed NEI 16-03, Rev.1 and the proposed methods for developing a NAM 3

monitoring program. For the reasons discussed in this SE, the staff has determined that a NAM 4

monitoring program implementing the NEI 16-03, Rev. 1 program will be able to detect 5

degradation of neutron absorbing material and provides assurance that the ability of the NAM to 6

provide the criticality control relied upon in the AOR is maintained.

7 8

The NRC staff finds that the requirements of 10 CFR 50.68(b)(4), GDC 61, and GDC 62, as well 9

as the guidance provided in SRP 9.1.1, SRP 9.1.2, and the GALL, Rev. 2, would be satisfied 10 with respect to NAMs and the NAM monitoring program if referenced in an LAR requesting use 11 of the program, and, for an application requesting use of i-LAMP as an alternative, that meets 12 the limitation stated in this SE. Accordingly, the NRC staff has concluded that NEI 16-03, Rev. 1 13 is acceptable for referencing in an application requesting approval of a NAM monitoring 14 program.

15 16 Each licensee adopting NEI 16-03, Rev. 1 will need to implement it in accordance with its plant-17 specific processes and licensing basis. This will involve review under the plant commitment 18 control process and 10 CFR 50.59. Either of these processes could result in the need for a 19 plant-specific license amendment request. Each licensee will need to make its own evaluation in 20 this regard under its site-specific change control program.

21

6.0 REFERENCES

22 23

1. Letter from R. McCullum (NEI) to J. Donoghue (NRC), Transmittal of Guidance Document 24 NEI 16-03, Revision 1, "Request for Review and Endorsement of NEI 16-03, Guidance for 25 Monitoring of Fixed Neutron Absorbers in Spent Fuel Pools, Revision 1 dated August 2022,"

26 August 19, 2022 (Agencywide Documents Access and Management System (ADAMS) 27 Accession No. ML22231B042).

28 29

2. Nuclear Energy Institute Guidance Document NEI 16-03, Revision 1, "Request for Review 30 and Endorsement of NEI 16-03, Guidance for Monitoring of Fixed Neutron Absorbers in 31 Spent Fuel Pools," August 2022 (ADAMS Accession No. ML22231B043 (Non-Proprietary).

32 33

3. Electric Power Research Institute (EPRI) Technical Report 3002018497, Industrywide 34 Learning Aging Management Program (i-LAMP): Global Neutron Absorber Material 35 Monitoring Program for Spent Fuel Pools, August 2022 (ADAMS Accession 36 No. ML22231B044 (Non-Proprietary).

37 38

4. Letters from R. McCullum (NEI) to J. Donoghue (NRC), "Supplement to NEIs Request for 39 Review and Endorsement of NEI 16-03, Guidance for Monitoring of Fixed Neutron 40 Absorbers in Spent Fuel Pools, Revision 1, dated August 19, 2022", October 12, 2023, 41 (ADAMS Accession No. ML22298A281), and Response to NRC Request for Supplemental 42 Information Supporting the Acceptance review of NEI 16-03, Rev. 1, Guidance for 43

OFFICIAL USE ONLY OFFICIAL USE ONLY Monitoring of Fixed Neutron Absorbers in Spent Fuel Pools, December 15, 2022 (ADAMS 1

Accession Nos. ML22349A656), and Response to NRC Request for Additional Information 2

Supporting the Review of NEI 16-03, Rev. 1, Guidance for Monitoring of Fixed Neutron 3

Absorbers in Spent Fuel Pools, May 23, 2023 (ADAMS Accession Nos. ML23143A306),

4 and Letter from B. Montgomery (NEI) to NRC, NRC Review of NEI 16-03, Guidance for 5

Monitoring of Fixed Neutron Absorbers in Spent Fuel Pools August 24, 2023 (ADAMS 6

Accession No. ML23236A503).

7 8

5. Nuclear Energy Institute 16-03, Guidance for Monitoring of Fixed Neutron Absorbers in 9

Spent Fuel Pools, Revision 0-A, May 2017 (ADAMS Accession Nos. ML17263A133 and 10 ML16354A486 (FSE)).

11 12

6. U.S. Nuclear Regulatory Commission, NUREG-0800, "Standard Review Plan for the Review 13 of Safety Analysis Reports for Nuclear Power Plants" (SRP), Section 4.2, "Fuel System 14 Design," Revision 3, March 2007 (ADAMS Accession No. ML070740002).

15 16

7. U.S. Nuclear Regulatory Commission, Standard Review Plan, Section 9.1.1, Criticality 17 Safety of Fresh and Spent Fuel Storage and Handling, NUREG-0800, Revision 3, 18 March 2007 (ADAMS Accession No. ML070570006).

19 20

8. U.S. Nuclear Regulatory Commission, Standard Review Plan, Section 9.1.2, New and 21 Spent Fuel Storage, NUREG-0800, Revision 4, March 2007 (ADAMS Accession 22 No. ML070550057).

23 24

9. U.S. Nuclear Regulatory Commission, Generic Aging Lessons Learned (GALL) Report, 25 NUREG-1801, Revision 2, December 2010 (ADAMS Accession No. ML103490041).

26 27

10. U. S. Nuclear Regulatory Commission (NRC) E-mail to NEI Final Request for Additional 28 Information - NEI 16-03, Guidance for Monitoring of Fixed Neutron Absorbers in Spent Fuel 29 Pools, Revision 1 (EPID No. L-2022-NTR-0002) April 24, 2023 (ADAMS Accession 30 No. ML23102A099).

31 32

11. U.S. Nuclear Regulatory Commission, Guide for Validation of Nuclear Criticality Safety 33 Calculational Methodology, NUREG/CR-6698, January 2001 (ADAMS Accession 34 No. ML050250061).

35 36 Principal Contributor: Matthew Yoder, NRR 37 38 Date:

39 40