ML23052A063

License Amendment Request to Modify the Long-Term Coupon Surveillance Program

ML23052A063
Person / Time
Site:	Calvert Cliffs
Issue date:	02/21/2023
From:	David Helker Constellation Energy Generation
To:	Office of Nuclear Reactor Regulation, Document Control Desk
References
Download: ML23052A063 (1)

Text

200 Exelon Way Kennett Square, PA 19348 www.Constellation.com 10 CFR 50.90 February 21, 2023 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555-0001 Calvert Cliffs Nuclear Power Plant, Unit 1 Renewed Facility Operating License No. DPR-53 Docket No. 50-317

Subject:

License Amendment Request to Modify the Long-Term Coupon Surveillance Program

Reference:

Letter from D. V. Pickett (USNRC) to J. A. Spina (CCNPP), dated August 27, 2008, Amendment No. 288 regarding Long-Term Coupon Surveillance Program (ML08218478)

In accordance with 10 CFR 50.90, Application for amendment of license, construction permit, or early site permit, Constellation Energy Generation, LLC (CEG) requests approval of a change to Renewed Facility Operating License DPR-53 for Calvert Cliffs Nuclear Power Plant, Unit 1 (CCNPP, Unit 1).

The proposed changes will revise the CCNPP, Unit 1 licensing basis by modifying the Long-Term Coupon Surveillance (LTCS) Program approved in Amendment 288 (Reference) for the carborundum samples located in the CCNPP, Unit 1 Spent Fuel Pool (SFP). The LTCS Program verifies that the carborundum degradation rates assumed in the CCNPP, Unit 1 criticality analysis will remain valid. The proposed changes to the LTCS program would:

• Revise the weight change acceptance criteria to < 38 percent for two coupons in a packet sample location (combined weight of upper and lower coupon by location) compared to baseline.

• Modify the visual examination criteria to exclude degradation from packet configuration-related erosion.

• Clarify the areal density testing frequency and associated corrective actions.

The remaining LTCS Program acceptance criteria and corrective actions would remain unchanged.

License Amendment Request to Modify the Long-Term Coupon Surveillance Program February 21, 2023 Page 2 provides an evaluation of the proposed changes, including an analysis of the no significant hazards consideration. Attachment 2 provides illustrative figures of the coupon tree and package configurations, for information only. Attachment 3 provides a reference letter from Nuclear Energy Services, Inc. to CCNPP that documents the initial Carborundum coupon data, for information only.

The proposed changes have been reviewed by the CCNPP Plant Operations Review Committee in accordance with the requirements of the CEG Quality Assurance Program.

CEG requests approval of the proposed license amendment by February 21, 2024. Once approved, the amendment shall be implemented within 60 days. This implementation period will provide adequate time for the affected station documents to be revised using the appropriate change control mechanisms.

In accordance with 10 CFR 50.91, Notice for public comment; State consultation, paragraph (b), CEG is notifying the State of Maryland of this application for license amendment by transmitting a copy of this letter and its attachments to the designated State Official.

There are no regulatory commitments contained within this letter. Should you have any questions concerning this submittal, please contact Wendi Para at (267) 533-1105.

I declare under penalty of perjury that the foregoing is true and correct. This statement was executed on the 21st day of February 2023.

Respectfully, David P. Helker Sr. Manager - Licensing Constellation Energy Generation, LLC Attachments: 1. Evaluation of Proposed Changes

2. Coupon Tree and Package Configuration (For Information Only)

3. Letter from J.P. Scoran (Nuclear Energy Services, Inc.) to K.A. Milos (Baltimore Gas and Electric, Calvert Cliffs), Process Surveillance Audit of Carborundum prior to the start of fabrication of poison material, dated 02/07/1980 (For Information Only) cc: USNRC Regional Administrator, Region I USNRC Senior Resident Inspector, CCNPP USNRC Project Manager, CCNPP S. Seaman, State of Maryland

ATTACHMENT 1 Evaluation of Proposed Changes Calvert Cliffs Nuclear Power Plant Unit 1 Renewed Facility Operating License No. DPR-53 Docket No. 50-317

Subject:

License Amendment Request to Modify the Long-Term Coupon Surveillance Program 1.0

SUMMARY

DESCRIPTION 2.0 DETAILED DESCRIPTION 2.1 System Description 2.2 Program Description 2.3 Current Requirements 2.4 Description of Proposed Changes 2.4.1 Weight Change Criteria Modification 2.4.2 Visual Examination Corrective Action Criteria Modification 2.4.3 Areal Density Testing Frequency and Corrective Actions Clarification

3.0 TECHNICAL EVALUATION

3.1 Weight Change Criteria Modification 3.2 Visual Examination Corrective Action Criteria Modification 3.3 Areal Density Testing Frequency and Corrective Actions Clarification

4.0 REGULATORY EVALUATION

4.1 Applicable Regulatory Requirements/Criteria 4.2 No Significant Hazards Consideration 4.3 Conclusions

6.0 REFERENCES

License Amendment Request to Modify the Long-Term Coupon Surveillance Program Page 1 1.0

SUMMARY

DESCRIPTION In accordance with 10 CFR 50.90, Application for amendment of license, construction permit, or early site permit, Constellation Energy Generation, LLC (CEG) requests approval of a change to Renewed Facility Operating License DPR-53 for Calvert Cliffs Nuclear Power Plant, Unit 1 (CCNPP, Unit 1).

The proposed changes will revise the CCNPP, Unit 1 licensing basis by modifying the Long-Term Coupon Surveillance (LTCS) Program approved in Amendment 288 (Reference 1) for the carborundum samples located in the CCNPP, Unit 1 Spent Fuel Pool (SFP). The LTCS Program verifies that the carborundum degradation rates assumed in the CCNPP, Unit 1 criticality analysis will remain valid. The proposed changes to the LTCS program would:

• Revise the weight change acceptance criteria to < 38 percent for two coupons in a packet sample location (combined weight of upper and lower coupon by location) compared to baseline.

• Modify the visual examination criteria to exclude degradation from packet configuration-related erosion.

• Clarify the areal density testing frequency and associated corrective actions.

After incorporating the proposed changes, the acceptance criteria for the surveillance program will be as follows:

a. Visual: No gross changes or deterioration excluding packet configuration-related erosion.

b. Weight: Any change < 38 percent for two coupons in a packet sample location compared to baseline.

c. Length and Width: Any change of +/- 0.5 inches compared to baseline.

d. Areal density: 10B content of 0.0177 g/cm2.

After incorporating the proposed changes, the corrective actions for the surveillance program will be as follows:

• Coupon does not meet established acceptance criteria for visual examinations, dimensional measurements, or weight measurements.

o Evaluate as part of the corrective action program to determine if expansion of the surveillance program is necessary.

• Coupon does not meet established acceptance criteria for areal density testing.

o Expand the surveillance program to remove additional coupons for visual examinations, dimensional measurements, weight measurements, and areal density testing.

• Established acceptance criteria for expanded surveillance program not met.

o Perform an investigation evaluating the neutron absorbing capabilities (i.e., the impact on criticality control would be evaluated).

License Amendment Request to Modify the Long-Term Coupon Surveillance Program Page 2 2.0 DETAILED DESCRIPTION 2.1. System Description The CCNPP SFP is located in the Auxiliary Building and provides underwater storage of spent fuel assemblies after their removal from both CCNPP reactor vessels (Units 1 and 2).

The pool, designed in two halves, can accommodate 1830 assemblies and one spent fuel shipping cask. The CCNPP, Unit 1 half of the SFP contains storage racks in six 10x10, two 8x10, and one 7x10 array. The storage racks consist of vertical cells grouped in parallel rows (arrays). The pool is constructed of reinforced concrete and lined with stainless steel.

The neutron absorbing material in the CCNPP, Unit 1 SFP storage racks is borated sheets inserted between the walls of the fuel rack cells. The sheets used in the CCNPP, Unit 1 SFP are made of a composite material (carborundum sheet) consisting of a boron carbide (B 4 C) powder in a fiberglass matrix.

Sample coupons of the Carborundum were included on the Long-Term Surveillance Assembly (LTSA) and are included on the Accelerated Surveillance Assembly (ASA). The LTSA coupon tree was placed in a SFP rack location that was to see typical doses from fuel as the fuel aged in the SFP. The ASA coupon tree was placed among freshly discharged fuel following each refueling and, over time, received higher exposure than the LTSA coupons.

CCNPP, Unit 1 License Amendment 267 (Reference 2) included a license condition that required CCNPP to develop a new long-term coupon surveillance program for the Carborundum samples. With only five accelerated sample coupons remaining, the intervals for sampling would have to be increased to allow for a sampling program for the extended life of the plant. Proceeding with these much longer ASA sample intervals (i.e., approximately every eight years) was not an acceptable approach, and therefore the surveillance program was modified, as approved in 2008 by CCNPP, Unit 1 License Amendment 288 (Reference 1).

The new Carborundum coupon surveillance program would use the remaining accelerated samples from the ASA, on a four-year cycle beginning in 2005, followed by the remaining eight long-term samples from the discontinued LTSA, continuing on a four-year cycle through 2053. To make the eight long-term samples available for this new surveillance program, the existing LTSA coupon surveillance program was discontinued in 2004. These eight LTSA samples were then subjected to accelerated doses so that they are expected to have exposures comparable to the ASA samples when it is time for the first of these eight to be sampled (i.e., beginning in 2025).

The ASA coupon tree is a fuel assembly sized item that is placed in the spent fuel storage racks. Each of the four sides of the coupon tree has coupon packets attached vertically to the outside of the assembly (LAR Attachment 2, Figure 1). A coupon packet consists of four individual coupons (LAR Attachment 2, Figure 2). The samples on each side of the assembly receive dose primarily from the fuel in the storage rack location adjacent to that side.

To accelerate doses to the eight remaining LTSA samples, they were placed onto new coupon trees that will allow the coupons to see higher doses from fuel. The two new LTSA HOLTEC coupon trees are fuel assembly sized coupon trees that were placed in the space between racks in the SFP instead of being placed inside a rack location. This allowed the sample coupons to see dose from the fuel that is in the rack locations on both sides of the coupons. The dose on the accelerated LTSA coupons is expected to exceed the ASA coupons before the ASA coupons are exhausted. One side of each of the new LTSA

License Amendment Request to Modify the Long-Term Coupon Surveillance Program Page 3 HOLTEC coupon trees has four or five coupon packets attached vertically to the outside of the assembly (LAR Attachment 2, Figure 3). The samples on each side of the assembly receive dose primarily from the fuel in the storage rack location adjacent to that side.

2.2 Program Description The CCNPP, Unit 1 LTCS program is designed to provide both accelerated and long-term exposure to gamma radiation and borated SFP water and it also allows for carborundum coupons to be removed from the SFP for examination. The LTCS program provides for periodic monitoring of the condition of the neutron absorption material in the SFP.

Sufficient B 4 C in the borated sheets are required to maintain a subcriticality minimum of five percent, at a 95 percent probability, 95 percent confidence level in the SFP. The method of confirming the borated sheets will have sufficient B 4 C currently consists of an accelerated LTCS program that has been in use since 2004. The LTCS program uses periodic testing of the sample coupons that are representative of the material in the SFP racks. The LTCS program uses five accelerated samples from the ASA, on a four-year cycle beginning in 2005, followed by the remaining eight long-term samples from the discontinued LTCS, continuing on a four-year cycle through 2053. The LTCS program provides data to support the prediction of B 4 C loss over the life of the racks by monitoring the degradation of the neutron absorbing material. Until 2004, the original ASA coupon surveillance program was used to determine degradation of the neutron absorbing material; the program was discontinued in 2004 to address the expanded lifetime of the SFP racks.

Coupon packets are removed every four years in accordance with the approved LTCS program. When a packet of coupons is removed, visual examination and areal density testing are performed, and dimensional and weight measurements are taken on all coupons removed.

NOTE: Coupons are not returned to the coupon tree following areal density testing.

Areal density testing is performed offsite and may result in the integrity of the coupon being compromised.

If a coupon does not meet the established acceptance criteria, the current LTCS program requires expanding the set to remove additional coupons from the SFP and performing areal density testing on the initial set of coupons and the expanded set, regardless of whether areal density testing was scheduled. Subsequently, if the acceptance criteria for the expanded surveillance program are not met then CCNPP will perform an investigation evaluating the neutron absorbing capabilities that specifically evaluates the impact on criticality control. This corrective action does not take into account that CCNPP, Unit 1 is currently performing areal density testing on all removed coupons.

CCNPP has committed to provide the results of all surveillances performed per the LTCS program to the NRC within six-months of completion of the surveillance. The reporting includes historical results and the most recent inspection results. After NRC approval of the LTCS program in 2008 (Reference 1), CCNPP submitted to the NRC the results of the program as documented in References 3, 4, 5, and 6.

License Amendment Request to Modify the Long-Term Coupon Surveillance Program Page 4 2.3 Current Requirements Consistent with the NEI 16-03 (Reference 7) guidance for basic and full coupon testing to identify whether unanticipated changes are occurring, the CCNPP LTCS program requires performance of visual examinations and dimensional, weight measurements (basic), and areal density (full) testing.

The current LTCS programs acceptance criteria as stated in procedure FTM-86-003R, (Reference 8) align with what NEI 16-03 considers to be the basic coupon testing. This testing is as follows:

• Visual Examination - The visual examination consists of inspecting for evidence of gross changes or deterioration.

• Dimensional Measurement - Any change in a length or width measurement of +/- 0.5 inches compared to baseline.

• Weight Measurement - Any change in weight of +/- 26 percent compared to baseline.

These parameters focus on identifying whether changes are occurring in the carborundum materials. NEI 16-03 states that basic testing is appropriate when previous testing and operating experience of the material indicates that there are no degradation mechanisms that would result in loss of 10B areal density that would affect reactivity. NEI 16-03 recommends that basic testing occur at least every ten years; CCNPP performs this testing every four years.

CCNPPs LTCS program also includes acceptance criteria for areal density testing, considered by NEI 16-03 to be a full coupon test. The LTCS programs acceptance criteria is as follows:

• Areal density - 10B content of 0.0177 g/cm2 (combined areal density of upper and lower coupon by location).

This parameter focuses on quantifying changes occurring in the materials. NEI 16-03 recommends that full testing occur at least every ten years; CCNPP performs this testing every four years.

2.4 Description of Proposed Changes After incorporating the proposed changes, the acceptance criteria for the surveillance program will be as follows:

a. Visual: No gross changes or deterioration excluding packet configuration-related erosion.

b. Weight: Any change of < 38 percent for two coupons in a packet sample location compared to baseline.

c. Length and Width: Any change of +/- 0.5 inches compared to baseline.

d. Areal density: 10B content of 0.0177 g/cm2.

License Amendment Request to Modify the Long-Term Coupon Surveillance Program Page 5 After incorporating the proposed changes, the corrective actions for the surveillance program will be as follows:

• Coupon does not meet established acceptance criteria for visual examination, dimensional measurements, or weight measurements.

o Evaluate as part of the corrective action program to determine if expansion of the surveillance program is necessary.

• Coupon does not meet established acceptance criteria for areal density testing.

o Expand the surveillance program to remove additional coupons for visual examinations, dimensional measurements, weight measurements, and areal density testing.

• Established acceptance criteria for expanded surveillance program not met.

o Perform an investigation evaluating the neutron absorbing capabilities (i.e., the impact on criticality control would be evaluated).

2.4.1 Weight Change Criteria Modification The criticality analysis of the CCNPP Unit 1 SFP (Reference 9, Attachment 4) indicates that the racks Carborundum total thickness is 0.09 inches, which was built from two 0.045 inch Carborundum sheets (LAR Attachment 3). The thickness of each Carborundum coupon is also 0.045 inches. Each coupon packet (LAR Attachment 2, Figure 2) includes four coupons (e.g., 1U (upper), 2U, 1L (lower), and 2L); together two coupons with the same sample location (e.g., 1U, 1L), represent the thickness of the racks Carborundum.

The current acceptance criteria for long-term coupon weight measurements is limited to any change in weight of +/- 26 percent for one coupon compared to baseline. The proposed change would revise the acceptance criteria to < 38 percent compared to baseline for two coupons in a packet sample location (combined weight of upper and lower coupon by location) compared to baseline.

This change would not impact the frequency of testing or how the testing is performed. This change would not impact the areal density criteria or the ability to identify degradation mechanisms that would result in loss of 10B areal density and would affect reactivity.

2.4.2 Visual Examination Corrective Action Criteria Modification The current acceptance criteria for the visual inspection is any evidence of gross changes or deterioration. The corrective actions include the requirement to expand the surveillance program to remove additional coupons for visual examinations. However, the criteria does not take into account erosion from the packet edge and inspection hole.

NOTE: Bracket covers were fabricated and installed to cover the inspection holes in 2016 (Reference 10).

The proposed change will modify the acceptance criteria to exclude flow-induced erosion at the coupon edges and coupon packet inspection hole to prevent the licensee from failing visual examinations due to rack design-related flow-induced erosion.

License Amendment Request to Modify the Long-Term Coupon Surveillance Program Page 6 This change would not impact the frequency of testing. This change would not impact the areal density criteria or the ability to identify service-related degradation mechanisms that would result in loss of 10B areal density and would affect reactivity.

2.4.3 Areal Density Testing Frequency and Corrective Actions Clarification In the CCNPP procedure, FTM-86-003R (Reference 8), areal density testing is performed as a corrective action if a coupon does not meet established acceptance criteria for visual examinations, dimensional, or weight measurements. However, the corrective action does not take into account that areal density testing is performed on all coupons removed during the performance of coupon testing every four years. The proposed change will clarify the corrective actions to prevent CCNPP from unnecessarily repeating areal density testing.

This change would not impact the frequency of testing. This change would not impact the areal density criteria or the ability to identify service-related degradation mechanisms that would result in loss of 10B areal density and would affect reactivity.

3.0 TECHNICAL EVALUATION

3.1 Weight Change Criteria Modification The current coupon weight change limit of +/- 26 percent was originated following the license renewal of CCNPP. During plant license renewal, CCNPP agreed to evaluate the Carborundum rack material for a service life of ten years after the period of extended operation. The Carborundum manufacturer's original test program had shown that the only notable changes in the sheet material with irradiation to 1011 rad (simulating a 40-year lifetime) were a 20 percent weight loss and 15 percent boron reduction (Reference 11, Enclosure 1). Based on this information, a boron loss of 26 percent was calculated as 70/40 x 15 percent (15 percent areal density loss over 40 years, extrapolated to 70 years) for use following license renewal. Therefore, the CCNPP, Unit 1 criticality analysis (Reference 9, Attachment 4) performed after plant license renewal evaluated a 10B areal density of 0.0177 g/cm2, which represented a 26 percent reduction over the 0.09 inches thick material with 0.024 g/cm2 (LAR Attachment 3) required by the specification. Since weight loss exceeded boron reduction under the carborundum manufacturers test conditions, use of a 26 percent reduction for the weight loss criteria in the aging management program was considered conservative during a time when areal density testing was not being performed. Following the first areal density test required by CCNPP, Unit 1 License Amendment 288 (Reference 1), manufacturing information located in plant history revealed that the Carborundum sheets installed in the Unit 1 SFP racks consisted of two layers, each 0.045 inches thick with an initial value reference of 10B areal density of 0.0144 g/cm2 to 0.0153 g/cm2 (Reference 9, Attachment 4). This information also indicated that similar material demonstrated a minimum of 0.012 g/cm2 after 1011 rad gamma exposure. Thus, the weight change acceptance criteria that was based on a reduction from 0.024 g/cm2 (which represents a combination of two coupons, e.g., 1U and 1L) is highly conservative.

The more appropriate weight change limit, which is based on as-built 10B areal density (AD ab ), is 38.5 percent (38.5 percent is conservatively rounded down to 38 percent in this LAR). Two coupons in a packet sample location correspond to the as-built thickness and as-built areal density; therefore, the proposed weight change limit is per two coupons.

License Amendment Request to Modify the Long-Term Coupon Surveillance Program Page 7 The weight change is calculated as

( 2) (0.0288 0.0177)

= (100) = (100) = 38.5%

( 2) 0.0288 where (AD m ) is the Carborundum expected minimum 10B areal density of one coupon in the SFP racks (0.0144 g/cm2), and (AD c ) is the Carborundum 10B areal density credited in criticality analyses of record (0.0177 g/cm2).

The proposed acceptance criteria is conservative because the weight change due to the flow induced erosion caused by an inspection hole in the coupon packet cover will not be adjusted. Thus, the weight change is overestimated considering the cover of the actual carborundum plates in the SFP racks does not have any hole at the height of the fuel active region. In addition, the weight reduction bounds the 10B areal density reduction. It is discussed in the Carborundum Handbook (Reference 10, Enclosure 1) that Analysis of the sheet material after exposure to 109 gray (1011 rad) showed a reduction in boron content of 15%, compared to the noted 20% weight loss of the material.

3.2 Visual Examination Corrective Action Criteria Modification Since 2005 most coupons pulled out of the CCNPP SFP have exhibited erosion on the edges and in a center, circular-sized area. As detailed in the CCNPP Unit 1 Response to GL 2016-01 (Reference 11),

The flow-induced erosion at the coupon packet and the rack inspection holes is considered to only exist at those locations based on a thermal-hydraulic review of the rack geometry. The flow rate in the fuel storage rack channels is determined by decay heat driven natural circulation, which is predominantly axial flow. However, the presence of the inspection holes in the channels acts as a bluff body, resulting in the appearance of turbulent eddy and secondary flow at the hole. The combined axial and recirculating flows at the inspection hole over an extended period cause flow induced erosion to any surface which is present at the hole, whether it be the coupon or the rack absorber sheet (note that surface erosion is proportional with the square of mass flow rate). The nature of the turbulent eddy flow would not impact the Carborundum material that is not adjacent to the hole.

This degradation is unrelated to and not representative of degradation due to exposure to gamma radiation or borated SFP water on the neutron absorbing coupon material. However, without clarifying the acceptance criteria this degradation will and has caused failure of the visual examination acceptance criteria. Failure requires subsequent corrective action, specifically, the removal of additional coupons for areal density measurement. As stated above in Section 2.1, coupons are not returned to the coupon tree after areal density testing, which means the population of coupons is reduced every time a coupon fails the visual criteria. Limiting unnecessary use of areal testing helps to preserve the population of coupons in the CCNPP LTCS program.

License Amendment Request to Modify the Long-Term Coupon Surveillance Program Page 8 In addition, degradation from the package-related erosion is included, conservatively, in other testing acceptance criteria. Specifically,

• The coupons length and width are measured in the dimensional examination. This dimensional examination will not be adjusted for packet-related erosion losses and will conservatively represent the edge erosion acceptability.

• The weight change for all coupons is measured in the weight examination. As discussed in Section 3.1, the weight change will not be adjusted for packet-hole related erosion losses and will conservatively represent the weight change acceptability.

Therefore, packet-related erosion losses should not be considered during visual examinations conducted in the CCNPP LTCS program as the condition is adequately monitored thru dimensional and weight measurements and incorporating it in the visual examinations could result in unnecessary, restrictive corrective action.

3.3 Areal Density Testing Frequency and Corrective Actions Clarification As documented in the CCNPP Response to Request for Additional Information Regarding Generic Letter 2016-01, and accepted in the subsequent NRC letter, Closeout of Generic Letter 2016-01, "Monitoring of Neutron-Absorbing Materials in Spent Fuel Pools" (References 11 and 12) areal density testing is required to be performed on all coupons removed during the performance of coupon testing.

As a corrective action, areal density testing is currently required to be performed on a coupon that does not meet established acceptance criteria for visual examinations or dimensional and weight measurements. If, after areal density testing, the results are satisfactory, then expansion of the surveillance program will be determined by evaluations done as part of the corrective action program. If the areal density testing is unsatisfactory, the corrective action required additional samples to be removed and tested. Since areal density testing is performed on all coupons removed from the SFP, the corrective action should be revised to remove the areal density repetitive testing as a corrective action if a coupon does not meet established acceptance criteria for visual examinations, dimensional, or weight measurements.

Revising the corrective actions would also limit the number of coupons not returned to the coupon tree after areal density testing which would help preserve the population of coupons in the CCNPP LTCS program.

4.0 REGULATORY EVALUATION

4.1 Applicable Regulatory Requirements/Criteria The effectiveness of the neutron absorbing materials installed in the CCNPP SFP storage racks ensures that the effective neutron multiplication factor (k eff ) does not exceed the values and assumptions used in the criticality analysis of record and other licensing basis documents. The analysis of record is the basis, in part, for demonstrating compliance with plant technical specifications and with the applicable NRC regulations. Degradation or deformation of the credited neutron absorbing material may reduce safety margin and potentially challenge the subcriticality requirement. Neutron absorbing materials utilized in SFP racks exposed to treated water or treated borated water may be susceptible to reduction of neutron absorbing capacity, changes in dimension, and/or loss of material that increases

License Amendment Request to Modify the Long-Term Coupon Surveillance Program Page 9 k eff . CCNPP implemented the LTSC program to ensure that degradation of the Carborundum, consisting of a boron carbide (B 4 C) powder in a fiberglass matrix, used in the SFP will be detected.

The proposed changes have been evaluated to determine whether applicable regulations and requirements continue to be met. CEG has determined that the proposed changes do not require any exemptions or relief from regulatory requirements from the following current applicable regulations and regulatory requirements which were reviewed in making this determination:

• 10 CFR 50.68(b)(4), Criticality accident requirements, states that if the licensee does not credit soluble boron in the SFP criticality AOR, the k eff of the SFP storage racks must not exceed 0.95 at a 95 percent probability, 95 percent confidence level. If the licensee does take credit for soluble boron, the k eff of the SFP storage racks must not exceed 0.95 at a 95 percent probability, 95 percent confidence level, if flooded with borated water, and if flooded with unborated water, the k eff must remain below 1.0 at a 95 percent probability, 95 percent confidence level.

• GDC 61, Fuel storage and handling and radioactivity control, states that The fuel storage and handling, radioactive waste, and other systems which may contain radioactivity shall be designed to assure adequate safety under normal and postulated accident conditions. These systems shall be designed (1) with a capability to permit appropriate periodic inspection and testing of components important to safety

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

CCNPP, Unit 1 was not licensed to the 10 CFR 50, Appendix A, GDC. The CCNPP, Unit 1, Updated Final Safety Analysis Report (UFSAR), Appendix 1C, "AEC Proposed General Design Criteria for Nuclear Power Plants," references the 1974 Final Safety Analysis Report for an assessment of the plant against the 70 draft GDC published in 1967. The plant-specific requirements at CCNPP are unaffected by the proposed licensing change.

In conclusion, on the basis of the considerations discussed above, (1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, (2) such activities will be conducted in compliance with the Commission's regulations, and (3) the issuance of the amendment will not be inimical to the common defense and security or to the health and safety of the public.

4.2 No Significant Hazards Consideration Pursuant to 10 CFR 50.90, Application for amendment of license, construction permit, or early site permit, Constellation Energy Generation, LLC (CEG) requests approval of a change to Renewed Facility Operating License DPR-53 for Calvert Cliffs Nuclear Power Plant, Unit 1 (CCNPP, Unit 1).

The proposed change would clarify the areal density testing corrective actions and modify the weight and visual acceptance criteria of the carborundum samples located in the CCNPP, Unit 1 Spent Fuel Pool (SFP) tested in accordance with the Long-Term Coupon Surveillance (LTCS) program as approved in Amendment 288 (Reference 1). The LTCS program verifies

License Amendment Request to Modify the Long-Term Coupon Surveillance Program Page 10 that the carborundum degradation rates assumed in CCNPP analyses to prove subcriticality, remain valid.

CEG has evaluated whether a significant hazards consideration is involved with the proposed amendment by focusing on the three standards set forth in 10 CFR 50.92, Issuance of amendment, as discussed below:

1. Does the proposed change involve a significant increase in the probability or consequences of an accident previously evaluated?

Response: No.

The LTCS program supports evaluation of degradation of the neutron absorbing material in the CCNPP, Unit 1 Spent Fuel Pool (SFP). The function of the neutron absorbing material is to provide one means of maintaining criticality safety of the nuclear fuel stored in the SFP. The proposed change would clarify the areal density testing corrective actions and modify the weight and visual acceptance criteria. The remaining LTCS program acceptance criteria and corrective actions remain unchanged.

The postulated accidents for the SFP are focused on five types: (1) dropped fuel assembly on top of the storage rack, (2) a misloading accident, (3) an abnormal location of a fuel assembly, (4) loss-of-normal cooling to the SFP, and (5) dilution of boron in the SFP water. The proposed change has been evaluated for impact on the accident analyses. The accident analyses all remain within the regulatory acceptance criteria.

Therefore, the proposed change does not involve a significant increase in the probability or consequences of an accident previously evaluated.

2. Does the proposed change create the possibility of a new or different kind of accident from any accident previously evaluated?

Response: No.

The proposed change would clarify the areal density testing corrective actions and modify the weight measurement and visual inspection acceptance criteria. The remaining LTCS program acceptance criteria and corrective actions remain unchanged. No physical or operational changes are being made to the plant. The proposed change does not have any impact on the integrity of any plant system, structure, or component that initiates an analyzed event. The proposed change will not introduce new failure modes or effects and will not, in the absence of other unrelated failures, lead to an accident whose consequences exceed the consequences of accidents previously analyzed.

Therefore, the proposed change does not create the possibility of a new or different kind of accident from any previously evaluated.

3. Does the proposed change involve a significant reduction in a margin of safety?

Response: No.

The proposed change would clarify the areal density testing corrective actions and modify the weight measurement and visual inspection acceptance criteria. The remaining LTCS program acceptance criteria and corrective actions remain unchanged. The LTCS

License Amendment Request to Modify the Long-Term Coupon Surveillance Program Page 11 program overall provides assurance that the fuel will remain subcritical under all postulated conditions, and clarification of the areal density testing corrective actions and modification of the weight and visual acceptance criteria does not involve a significant reduction in a margin of safety.

The proposed change does not affect the safety analysis acceptance criteria for any analyzed event, nor is there a change to any safety analysis limit. The proposed change does not alter the manner in which safety limits, limiting safety system settings or limiting conditions for operation are determined, nor is there any adverse effect on those plant systems necessary to assure the accomplishment of protection functions. The proposed change will not result in plant operation in a configuration outside the design basis.

Therefore, the proposed change does not involve a significant reduction in a margin of safety.

Based on the above, CEG concludes that the proposed amendment presents no significant hazards consideration under the standards set forth in 10 CFR 50.92(c), and, accordingly, a finding of no significant hazards consideration is justified.

4.3 Conclusions In conclusion, based on the considerations discussed above, (1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, (2) such activities will be conducted in compliance with the Commissions regulations, and (3) the issuance of the amendment will not be inimical to the common defense and security or to the health and safety of the public.

5.0 ENVIRONMENTAL CONSIDERATION

The proposed change would clarify the areal density testing corrective actions and modify the weight measurement and visual inspection acceptance criteria. However, the proposed change does not involve (i) a significant hazards consideration, (ii) a significant change in the types or significant increase in the amounts of any effluents that may be released offsite, or (iii) a significant increase in individual or cumulative occupational radiation exposure.

Accordingly, the proposed change meets the eligibility criterion for categorical exclusion set forth in 10 CFR 51.22(c)(9). Therefore, pursuant to 10 CFR 51.22(b), no environmental impact statement or environmental assessment need be prepared in connection with the proposed change.

License Amendment Request to Modify the Long-Term Coupon Surveillance Program Page 12

6.0 REFERENCES

1. Letter from D. V. Pickett (NRC) to J. A. Spina (CCNPP), dated August 27, 2008, Amendment re: Long-Term Coupon Surveillance Program (ADAMS Accession No. ML082180478)

2. Letter from G. S. Vissing (NRC) to G. Vanderheyden (CCNPP), dated June 3, 2004, Amendment re: Increasing the Spent Fuel Pool Maximum Enrichment Limit (ADAMS Accession No. ML041040129)

3. Letter from J. J. Stanley (CCNPP) to NRC Document Control Desk, dated November 13, 2012, Long-Term Coupon Surveillance Program (ADAMS Accession No. ML12319A474)

4. Letter from K. F. Robinson (CCNPP) to NRC Document Control Desk, dated April 28, 2014, Long-Term Coupon Surveillance Program (ADAMS Accession No. ML14119A437)

5. Letter from M. D. Flaherty (CCNPP) to NRC Document Control Desk, dated April 25, 2018, Long-Term Coupon Surveillance Program (ADAMS Accession No. ML18117A228)

6. Letter from P. D. Navin (CCNPP) to NRC Document Control Desk, dated June 27, 2022, Long-Term Coupon Surveillance Program (ADAMS Accession No. ML22178A172)

7. Letter from K. W. Cummings to B. J. Benney, dated August 30, 2016, Submittal of NEI 16-03, Guidance for Monitoring of Fixed Neutron Absorbers in Spent Fuel Pools, Revision 0, dated August 2016, (ADAMS Accession No. ML16265A248)

8. FTM-86-003R, Rev. 2, Analysis of Neutron Absorbing Material in the Spent Fuel Pool Storage Racks and Management of Neutron Poison Coupon Trees, dated February 15, 2021

9. Letter from P. E. Katz (CCNPP) to NRC Document Control Desk, dated May 1, 2003, License Amendment Request: Increase to Spent Fuel Pool Maximum Enrichment Limit with Soluble Boron Credit, Attachments 1 Through G, (ADAMS Accession No. ML033140581).

10. Letter from J. A. Spina (CCNPP) to NRC Document Control Desk, dated May 10, 2007, Long-Term Coupon Surveillance Program for the Unit 1 Spent Fuel Pool, (ADAMS Accession No. ML071440224).

11. Letter from P. R Simpson (Exelon) to NRC Document Control Desk, dated January 25, 2018, Response to Request for Additional Information Regarding Generic Letter 2016-01 (ADAMS Accession No. ML18025A799)

12. Letter from D. A. Broaddus (NRC) to B. Hanson (Exelon), dated September 26, 2018, Closeout of Generic Letter 2016-01, "Monitoring of Neutron-Absorbing Materials in Spent Fuel Pools (ADAMS Accession No. ML18249A049)

ATTACHMENT 2 Coupon Tree and Package Configuration Calvert Cliffs Nuclear Power Plant, Unit 1 Renewed Facility Operating License No. DPR-53 Docket No. 50-317

Figure 1. Accelerated Surveillance Assembly (ASA) Coupon Trees Figure 2. Picture of a removed Carborundum coupon packet Figure 3. HOLTEC Long-Term Surveillance Assembly (LTSA) Coupon Trees ATTACHMENT 3 Letter from J.P. Scoran (Nuclear Energy Services, Inc.) to K.A. Milos (Baltimore Gas and Electric, Calvert Cliffs), Process Surveillance Audit of Carborundum prior to the start of fabrication of poison material, dated 02/07/1980 (For Information Only)

Calvert Cliffs Nuclear Power Plant, Unit 1 Renewed Facility Operating License No. DPR-53 Docket No. 50-317

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-1.i.d ::h 6-1/2 +/- 1 /1 6"

-thicknes s 0 . 045 + . 005

• .... ..: - . 010 Quantity 6650 p iece~

N£S 80A2759 , Rev l , Fabrication and Inspection Spccific4-tion Ht::S 81A056J, Rt.:v 5, Qu.nlity A ~s unmc~ I'1:or,ni.in l'lnn C.:irbci:ur.U.ur.t Quality Assurance: Plan No . A-80, Rev 0 wich i:..:v l t o the P.'.lckaging, Ha...,tllini:; nnd Shipping Procedure i.;Cfl.. s~c :: io n 2 .0 A-ffllCHtf!!?dT (/,.. . Jtvl Tl/IL VA lve R5FGRP'rk E

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confbr".' t o il::~...iechr:ic2l . Spccificction ~').;~:?~9 * ~~*1.i.': \'lith t he foflowin9 e.r.cept 10:}'.i. * ~'**

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" ... ;,::~~:~.-:;;i. ~;~;*;:<~\/('...~*;.~ :./.(*; '.~~~;~ 1 her~By ~ertify the above,

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ilos :

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Ccr)orundu~ ~oron ?rcd*Jcts Qu~ l i,ty Assura~ce -h* .. *eby '-cert'ifies' that .a 1l .

bo ron ~ubide r.ic:te;ial d~ l hcr*ed ;~o i.he a bo*ie ... enti otled

• purchase*:'~rd er conforn 'to :;ES Tl?ct~nical $£e'c_ific~\ion 8Qi;27 59 P.e~:t* l \*Ji ~)I th~ :~*fol1'cMin.g eY.ceot ion. * ** * *, ,* *. ~

• Ttri ck nes s (Sec: 5. 3 . 1 . c*) see attached Jloncon.f ormanc.e :*Rep9rt .. ( tlc!l'.:003)

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• In particular, Carborundum ~uallty..As's,u:ratn:e .c.e rtifies. -~~at this r::a t.er1al has al"l a v~roqe .. BlO Jooding of . . OJ4~ gr.i C10/cr.t2 *.ias prodiaced and. ~-h'a : si::: ilar rna t eri*al has , d~.ons-tra ,ted a ~it).ir.;um' . IJ12 gr:i Bi'0/cm2 after sif\o:.i1taneovs ex;>o sure ***co 1011 Ra.d G<fr:-r;1a ;a1i'Cl DI 'l..1ater .

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m~rcury , ccJd1:i iur1 or oth~r 10~*1 1,nelting point r.ietals. -~*

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hereby certify the above .

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