ML24268A277

Response to Connie Kline Questions About Holtec and Perry Exemptions

ML24268A277
Person / Time
Site:	Perry
Issue date:	11/25/2024
From:	Yen-Ju Chen Storage and Transportation Licensing Branch
To:	Kline C Public Citizen
Shared Package
ML24268A275	List: ML24268A276 ML24268A277 ML24268A279
References
Download: ML24268A277 (1)

Text

Enclosure Response to Questions About Holtec and Perry Exemptions 1.

According to the NRC, as of March 2024, there were 21 licensees who had loaded 200 CBS basket variant dry cask systems.

A. Please provide a list of the 21 licensees, the nuclear plants at which the 200 CBS basket variant dry casks are located, and the number of loaded variant dry cask systems at each plant.

This table presents the staffs understanding of how many CBS-variant casks were loaded at each plant prior to when we started issuing exemptions beginning in April 2024.

Plant Name Licensee

1. of Casks Arkansas Nuclear One Entergy Operations, Inc.

3 Browns Ferry Tennessee Valley Authority (TVA) 18 Calvert Cliffs Constellation Energy Generation Company, LLC (Constellation) 6 Clinton Constellation 5

Dresden Units 2 & 3 Constellation 4

Edwin I. Hatch Southern Nuclear Operating Company, Inc.

3 Hope Creek PSEG Nuclear, LLC 6

Indian Point Energy Center Unit 3 Holtec Decommissioning International, LLC 73 James A. FitzPatrick Constellation 6

LaSalle Constellation 8

Limerick Constellation 3

Nine Mile Point Constellation 9

Oyster Creek Holtec Decommissioning International, LLC 33 Peach Bottom Constellation 12 Perry Energy Harbor Nuclear Corp.

2 Sequoyah TVA 5

South Texas Project STP Nuclear Operating Company 10 Susquehanna Susquehanna Nuclear, LLC 6

Virgil C. Summer South Carolina Electric & Gas Company 4

Waterford Entergy Operations, Inc.

7 Watts Bar TVA 5

B. How many exemption requests have been received and granted to date?

As of November 25, 2024, we have received ten exemption requests and granted nine exemptions.

2 C. How many additional basket variant dry cask systems have been loaded since March 2024?

After March 2024, approximately 50 CBS casks were loaded by the end of August 2024, and additional 23 CBS casks may be loaded by the end of November 2024.

The CBS cask loadings after March 2024 were authorized by approved exemption requests.

Specifically for Perry, since NRC issued the exemption on May 8, 2024, Vistra Operations Company LLC (Vistra) registered two casks with NRC (ML24254A272) in September 2024, and, while not required, stated that both baskets are CBS design.

These two CBS baskets were loaded in accordance with the exemption approved by the NRC.

D. Are dry casks (ISFSl) monitored continuously for radiation?

E. lf not, what is the monitoring schedule?

The licensees are required to comply with the requirements in 10 CFR 72.104, Criteria for Radioactive Materials in Effluents and Direct Radiation from an ISFSI or MRS. Each licensee has its own program for monitoring/measuring and reporting the annual radioactive effluent release.

F. What radionuclides are monitored?

The effluent and environmental reports for operating reactors are publicly available:

https://www.nrc.gov/reactors/operating/ops-experience/tritium/plant-specific-reports/perr1.html G. ls ISFSI reporting separate from the reactor effluent/environmental reports and if so, where is it available at NRC.gov?

Each licensee has its own program for reporting the annual effluent release. Some licensees submit one report for both reactor and ISFSI, while others have separate reports. The effluent/environmental reports are available in each licensees docket file in ADAMS.

VISTRA submitted the 2023 Annual Radiological Effluent Release Report for the Perry Nuclear Power Plant, including the ISFSI, (ML24121A276) on April 22, 2024.

Based on the 2023 report, there is no indication of radiation doses above limits at Perry.

The following questions/comments refer to the 1/31/24 Safety Determination above.

2.

My general impression of this document is that within a three month period from September 2023 to January 2024, the NRC staff did a 180° minimizing, and dismissing the concerns raised in the 9/12/23 document above and making a number of assumptions.

The thin-walled multi purpose canister (MPC) is assumed to maintain its structural integrity during a tip over event so no water can enter the interior of the MPC, and any damaged fuel would remain within the MPC.

3 This is not assumed; Holtecs structural analyses, as described in its FSAR for both the HI-STORM 100 (ML24109A209) and HI-STORM FW (ML23170A029), shows that the canister is not breached in the event of a tipover.

Subcriticality is also assumed. "Nonetheless, should the fuel basket fail to maintain its structural integrity, and, in a worst-case scenario, allow the fuel assemblies and cladding to fail, the fuel will be maintained in a subcritical condition."

Subcriticality is not assumed. The analysis in the safety determination memo (ML24018A085) shows that it will be maintained even if the fuel basket in the canister fails and the fuel assemblies and cladding fail. Since the canister boundary is not breached in the tipover event, water cannot enter the canister. Without water to serve as a moderator, subcriticality is maintained since uranium enriched to 5 weight percent or less in the 235-uranium isotope cannot go critical.

lt is also assumed that while radiation released due to a basket tip over accident might exceed the one meter dose rate (p 5-6 "shielding Evaluation"),

site boundary dose rates would not be exceeded.

This is not an assumption. Holtec has shown that the shielding for both concrete cask designs remains essentially intact, with only localized concrete breaking off.

Holtecs analysis, which was reviewed by the NRC, also showed that the offsite dose at the site boundary (at least 100 meters from the ISFSI pad) would not increase because of damaged fuel inside a canister.

3.

According to p. 5 "Criticality Evaluation", assumptions are based on fresh fuel enriched to less than 5 wt.% 235U. The NRC has approved enrichment up to 8%

wt. 235U (see links below).

A. lf the CBS baskets in question continue to be used, will increased enrichment above 5% wt. 235U (and use of higher burnup fuel) be analyzed for a tip over accident?

Global Nuclear Fuel CoC etc.

https://adamswebsearch2.nrc.gov/webSearch2/main.jsp?AccessionNumber

=ML23191A.147 Louisiana Energy Services has also applied to increase enrichment above 5.5% wt. 235U but less than 10%.

https://adamswebsearch2.nrc.gov/webSearch2/main.jsp?AccessionNumber

=ML24052A385 Yes. NRC has not approved storage of greater than 5 wt.% fuel in Holtec storage system. Holtec would need a CoC amendment - which involves NRC review and approval - to increase either the enrichment or burnup of fuel to be stored in the canister, including any use of CBS baskets. Holtec is required to demonstrate safety, which would include a tipover event, for any amendment with increased enrichment and burnup. Currently the NRC has not received indications of such amendment request.

4.

Could you please briefly describe the accident scenario(s) that were considered under which a potential basket tip over could occur and the locations at a reactor site?

4 A cask tipover scenario is addressed in NUREG-2215 (ML20121A190), Standard Review Plan for Spent Fuel Dry Storage Systems and Facilities, section 4.5.3.3.1.

Holtec stated in the FSAR for both systems that the overpack does not tip over as a result of the accidents (i.e., tornado missiles, flood water velocity, and seismic activity) and its highly unlikely that the overpack will tipover during on-site movement due to the handling height or the use of a lifting device designed in accordance with the criteria for each system. Holtec performed the tipover analysis as a non-mechanistic accident to demonstrate the defense-in-depth features of the system design. Holtecs tipover analyses have shown that once on the storage pad, a cask will not tip over from an initiating event such as a design-basis earthquake or tornado missile impacts. (See HI-STORM 100 system FSAR, revision 24 (ML24109A209) section 11.2.3 and FW system FSAR, revision 10 (ML23170A029) section 12.2.3.)

5.

p7 "Fuel cladding is not relied upon for demonstrating safety and there is no requirement to demonstrate structural integrity of the cladding."

A. Why is there no requirement to demonstrate structural cladding integrity?

B. Why is cladding not relied upon as an additional redundant safety layer?

NRCs regulations are performance-based and prescribe what the applicant has to demonstrate to receive an NRC approval. The NRC does not, however, dictate precisely how the applicant meets the regulatory requirements. Some licensees rely upon fuel cladding as an additional redundant safety layer, but the regulations do not dictate that they do so. If the cladding is not relied upon for safety, then the retrievability requirements of 10 CFR 72.122(h) need to be met. In this case, the retrievability requirement of 10 CFR 72.122(h) is met through the recoverability of the MPC with the encapsulated fuel. Therefore, the cladding is not relied upon as an additional redundant safety layer.

C. Doesn't "rubblized", irretrievable fuel indicate cladding failure?

Rubblized fuel does indicate cladding failure; however, if the fuel is in a canister, then fuel can still be considered to be retrievable by normal means since the canister itself can be retrieved from the storage cask.

6.

While the NRC considers "rubblized" fuel an unlikely, hypothetical worse case scenario, the NRC acknowledges that a subcritical accident where fuel is "rubblized" would require additional shielding and worker protection {p. 5-6}

That is correct. If the fuel were to turn to rubble, a highly unlikely scenario, it could move downward due to gravity and potentially closer to the canister wall, raising dose rates for anyone close to the cask. Even if this highly unlikely scenario were to occur, the licensees radiation protection program would be able to detect this dose rate increase and take appropriate precautions (such as use of temporary shielding) for workers handling the cask. These safety precautions are described in the FSAR for HI-STORM 100 system, section 11.2.3.4.

7.

According to p. 4 "Thermal Evaluation", since Holtec did not perform thermal analysis, the NRC apparently performed its own thermal analysis or is relying on past thermal analyses.

5 The NRC reviewed past thermal analyses to assess the potential effects if the fuel were to become rubblized. Based upon this review, the staff determined that the fuel debris could collect at the bottom of a cask and cause localized heating. However, the staff assessed that it would not challenge the containment boundary because the canister shell is made of stainless steel which has a very high melting point. The staff also assessed that the pressure increase within the canister would not challenge the containment boundary.

8.

p. 6 "Structural Evaluation" indicates that stress limits could still be exceeded but assumes that the fuel will remain subcritical.

A. Have any additional stress/strain, elasticity, load transfer analyses been done?

Holtec provided an analysis that proposed to incorporate a new method of evaluation for stress/strain into Amendment No. 7 for the HI-STORM FW system (ML24199A236). As of the date of the Safety Determination Memo, the NRC had not completed the review of the methodology. However, the NRC has subsequently found the analysis to be acceptable (ML24199A236).

The following questions pertain to these documents (page #s are PDF):

2/27/24 Energy Harbor exemption request to load two Holtec MPC-B9 system baskets/canisters variants at the Perry reactor in Aug. 2024 https://adamswebsearch2.

nrc.gov/webSearch2/main.jsp?AccessionNumber=ML24058A180 3/26/24 EA/FONSI granting exemption for Holtec dry cask system(s) in question at Dresden https://adamswebsearch2.

nrc.gov/webSearch2/main.jsp?AccessionNumber=ML24066A034 5/3/24 EA/FONSI granting exemption for Holtec dry cask system(s) in question at Perry https://adamswebsearch2.nrc.gov/webSearch2/main.jsp?AccessionNumber=ML24 103A1 9.

p. 1 of Energy Harbor exemption request states, "Currently, EHNC plans to load MPC-89CBS systems during the summer 2024 dry cask campaign and during future campaigns."

"Future campaigns" appear to indicate that in February Energy Harbor expected that these variant basket designs would continue to be manufactured.

That is the same understanding that NRC has regarding the exemption request and Holtecs plans for manufacturing the MPC-89CBS.

10. According to p.1719 of the Perry License Renewal Application, Energy Harbor has already loaded two Holtec MPC-89 casks. "Currently the ISFSI has 25 MPC-68 and two MPC-89 systems on the pad."

https://adamswebsearch2.nrc.gov/webSearch2lmain.jsp?Accession Number=ML23184A081 A. When were the two existing MPC-89 systems loaded?

Per the registration requirements in 10 CFR 72.212(b)(2), licensees are not required to inform NRC which canisters they have loaded. However, in its renewal request,

6 Energy Harbor indicated that it was transitioning to MPC-89 in September 2022.

Energy Harbor provided registrations for two loaded casks in December 2022 (ML22346A219).

B. Are they the CBS variant baskets?

Yes.

11. p. 6-7 of the Dresden EA/FONSI states, "The staff considered the no-action alternative. The no-action alternative (denial of the exemption request) would require Constellation to unload spent fuel from the MPC68M-CBS in the HI-STORM 100 Cask System to bring it in compliance with the CoC. Unloading the cask would subject station personnel to additional radiation exposure, generate additional contaminated waste, increase the risk of a possible fuel handling accident, and increase the risk of a possible heavy load handling accident.

Furthermore, the removed spent fuel would need to be placed in the spent fuel pool, where it would remain until it could be loaded into an approved storage cask."

I don't see the precise language that is in the Dresden EA/FONSI about unloading and returning fuel to the pool in the 5/3/24 Perry EA/FONSI.

A. Does this mean that none of the basket variants have been loaded at Perry?

Based on information from licensees in item 1A above, Perry has loaded two CBS variant baskets. Perrys exemption requested the exemption to apply only to future loading of the systems. The language highlighted only applies to already loaded systems and thus, does not apply to Perrys exemption request.

B. Has a dry cask system (Holtec or another manufacturer) ever been unloaded and the fuel returned to the spent fuel pool?

No.

12. p. 5 of the Energy Harbor exemption request states, "lmprovements implemented through the new variant pertain to the external shims, which are between the basket periphery and the MPC shell, and the elimination of the difficult to manufacture friction-stir-weld (FSW) seams joining the raw edges of the basket panels."

A. For how many years were the "original design" baskets manufactured?

The storage cask designs were approved in 2000 for the HI-STORM 100 and 2011 for the HI-STORM FW.

B. Did Holtec ever indicate to the NRC that they were difficult to manufacture?

No.

7 C. Does "difficult" mean more "expensive" to manufacture, i.e. are the variants cheaper to manufacture?

NRC does not have information about the manufacturing costs as that is outside of the scope of our safety reviews of the cask design.

The following questions pertain to Holtec.

1.

Other than the Notice of Violations, what, if any, enforcement action has the NRC undertaken?

The notice of violation is the only enforcement action issued to Holtec regarding this non-compliance.

2.

ln response to the violations, what corrective actions has Holtec undertaken?

Holtec identified corrective actions in its response to the violation (ML24060A214).

Additionally, Holtec performed a root cause evaluation to provide long-term corrective actions to prevent recurrence of the violations. To date, Holtec has submitted amendment requests for both the HI-STORM 100 and HI-STORM FW to approve a new method of evaluation for the CBS baskets. NRC approved the method of evaluation in HI-STORM FW Amendment No. 7 (ML24199A236). HI-STORM 100 Amendment No. 19 was submitted on August 9, 2024 (ML24222A858) and is under review.

3.

What procedures have been implemented to prevent recurrence of a similar situation?

NRC identified the violations in NRC Inspection Report No. 07201014/2022-201, Enforcement Action No. EA-23-044 (ML24016A190). Holtecs response (ML24060A214) to the violation contains the following information: (1) the reason for the violations; (2) the corrective steps that have been taken and the results achieved; (3) the corrective steps that will be taken; and (4) the date when full compliance will be achieved.

4.

Does NRC consider that compliance has been or still needs to be restored?

As it relates to Holtecs violation, the NRC has determined that corrective actions will require Holtec to submit an amendment for HI-STORM 100 and HI-STORM FW systems in accordance with 10 CFR 72.244 or will require the individual licensees to submit an exemption in accordance with 10 CFR 72.7. The submittal of either an exemption or amendment does not guarantee the approval of the submittal.

As noted in response to question #2 above, the NRC has approved HI-STORM FW, Amendment No. 7, and Holtec has submitted Amendment No. 19 for HI-STORM 100 system.

5.

Could the NRC have ordered a recall of already delivered dry cask systems with the CBS basket variants and require Holtec to issue a licensee refund?

The NRC has broad authority to take actions to protect the public health and safety.

Because the NRC determined the violation involved an issue of very low safety

8 significance, there was not a need for any immediate action. NRC would not, however, have the authority to require Holtec to refund licensees.

6.

instead of issuing exemptions to load the CBS basket design variant dry cask systems, could the NRC have required temporary re-racking of the SFPs. which while not ideal, has been done for years?

The NRC has broad authority to take actions to protect the public health and safety.

Because the NRC determined the violation involved an issue of very low safety significance, there was not a need for any immediate action, nor a safety basis to order reactor licensees to make changes to their sites.

7.

Can the NRC issue monetary penalties?

Yes, in accordance with the NRC Enforcement Policy (ML24205A249), monetary penalties can be issued based on the safety significance of the violation as well as other factors.

8.

Can the NRC order Holtec to stop manufacturing the CBS basket design variants and return to manufacturing the "original design"?

The NRC has broad authority to take actions to protect the public health and safety.

Because the NRC determined the violation involved an issue of very low safety significance, there was not a need for any immediate action.

9.

I cannot find an accession number for Amendment No. 7 to CoC No. 1032 for the HI-STORM FW system that Holtec submitted.

Here are the submittals for HI-STORM FW Amendment No. 7:

Letter from Holtec International to NRC, HI-STORM FW Amendment 7 Request.

May 6, 2021. This package contains 29 attachments, and Attachments 5 and 7 through 21 are Proprietary Information and Not Publicly Available. ML21126A266.

Letter from Holtec International to NRC, HI-STORM FW Amendment 7 Responses to Requests for Supplemental Information. October 15, 2021. This package contains 19 attachments, and Attachments 1, 5, 7 through 10, and 18 are Proprietary Information and Not Publicly Available. ML21288A521.

Letter from Holtec International to NRC, HI-STORM FW Amendment 7 Responses to Request for Additional Information Part 1. July 11, 2022. This package contains 9 attachments, and Attachments 1, 5, 7, and 8 are Proprietary Information and Not Publicly Available. ML22192A215.

Letter from Holtec International to NRC, HI-STORM FW Amendment 7 Responses to Requests for Additional Information Part 1 - Additional Supporting Documents.

July 13, 2022. This package contains 3 attachments, and Attachments 1 and 2 are Proprietary Information and Not Publicly Available. ML22194A953.

9 Letter from Holtec International to NRC, HI-STORM FW Amendment 7 Responses to Requests for Additional Information Part 2. July 29, 2022. This package contains 7 attachments, and Attachments 3, 5, and 6 are Proprietary Information and Not Publicly Available. ML22210A145.

Letter from Holtec International to NRC, HI-STORM FW Amendment 7 RAI Responses Part 1 Clarification Call Action Items. September 15, 2022. This package contains 9 attachments, and Attachments 3, 6, and 8 are Proprietary Information and Not Publicly Available. ML22258A250.

Letter from Holtec International to NRC, HI-STORM FW Amendment 7 Responses to Requests for Additional Information Part 3. October 3, 2022. This package contains 3 attachments, and Attachment 1 is Proprietary Information and Not Publicly Available. ML22276A281.

Letter from Holtec International to NRC, HI-STORM FW Amendment 7 RAI 5-2 Response Clarification. December 1, 2022. ML22336A132 Letter from Holtec International to NRC, HI-STORM FW Amendment 9 Request.

February 17, 2022. ML22048C221.

Letter from Holtec International to NRC, HI-STORM FW Amendment 7 Responses to Requests for Additional Information Part 4. January 6, 2023. This package contains 10 attachments, and Attachments 1, 7, 8, and 9 are Proprietary Information and Not Publicly Available. ML23006A263.

Letter from Holtec International to NRC, HI-STORM FW Amendment 7 Responses to Requests for Additional Information Part 5. May 8, 2023. This package contains 10 attachments, and Attachments 1, 3, and 5 through 9 are Proprietary Information and Not Publicly Available. ML23128A302.

Letter from Holtec International to NRC, HI-STORM FW Amendment 7 RAI Responses Part 5 Clarification Call Action Items. June 30, 2023. This package contains eight attachments, and Attachments 2, 4, 6, and 7 are Proprietary Information and Not Publicly Available. ML23181A192.

Letter from Holtec International to NRC, HI-STORM FW Amendment 7 RAI Responses Part 5 Clarification Corrected Attachments 4 and 5. July 11, 2023. This package contains three attachments, and the attachment labeled as Attachment 4 is Proprietary Information and Not Publicly Available. ML23192A031.

Letter from Holtec International to NRC, HI-STORM FW Amendment 7 RAI 3-10 Response Clarification Call Action Items. August 15, 2023. This package contains three attachments, and Attachment 2 is Proprietary Information and Not Publicly Available. ML23227A248.

Letter from Holtec International to NRC, HI-STORM FW Amendment 7 RAI Response Clarifications (Part 3). November 17, 2023. This package contains eight attachments, and Attachments 2 and 4 through 7 are Proprietary Information and Not Publicly Available. ML23321A245.

10 Letter from Holtec International to NRC, HI-STORM FW Amendment 7 RAI Response Clarifications (Part 4). February 16, 2024. This package contains five attachments, and Attachments 1, 2, and 4 are Proprietary Information and Not Publicly Available. ML24047A323.

Letter from Holtec International to NRC, HI-STORM FW Amendment 7 RAI Response Clarifications (Part 5). April 8, 2024. This package contains 10 attachments, and Attachments 1, 3, and 5 through 9 are Proprietary Information and Not Publicly Available. ML24100A027.

10. Has Holtec submitted an additional amendment? lf so, what is its accession number?

Holtec submitted an amendment request for Amendment No. 19 to the HI-STORM 100 storage system on August 9, 2024 (ML24222A858).