ML21130A588

Supplemental Information Needed for Acceptance of Requested Licensing Actions to Adopt a Risk-Informed Approach to Address GSI-191 and Respond to Generic Letter 2004 02

ML21130A588
Person / Time
Site:	Callaway
Issue date:	05/11/2021
From:	Mahesh Chawla Plant Licensing Branch IV
To:	Diya F Ameren Missouri, Union Electric Co
Chawla M
References
EPID L 2021 LLE 0021, EPID L-2021-LLA-0059
Download: ML21130A588 (5)

Text

May 11, 2021 Mr. Fadi Diya Senior Vice President and Chief Nuclear Officer Ameren Missouri Callaway Energy Center 8315 County Road 459 Steedman, MO 65077

SUBJECT:

CALLAWAY PLANT, UNIT NO. 1 - SUPPLEMENTAL INFORMATION NEEDED FOR ACCEPTANCE OF REQUESTED LICENSING ACTIONS RE: LICENSE AMENDMENT AND REGULATORY EXEMPTIONS FOR A RISK-INFORMED APPROACH TO ADDRESS GENERIC SAFETY ISSUE-191 AND RESPOND TO GENERIC LETTER 2004-02 (EPID L-2021-LLA-0059 AND EPID L-2021-LLE-0021)

Dear Mr. Diya:

By letter dated March 31, 2021 (Agencywide Documents Access and Management System Accession No. ML21090A184), Union Electric Company (dba Ameren Missouri, the licensee), pursuant to Title 10 of the Code of Federal Regulations (10 CFR) Section 50.90, Application for amendment of license, construction permit, or early site permit, requested an amendment for the licensees final resolution to addressing the concerns of Generic Safety Issue (GSI)-191, Assessment of Debris Accumulation on PWR [Pressurized-Water Reactor] Sump Performance, and for responding to Generic Letter 2004-02, Potential Impact of Debris Blockage on Emergency Recirculation During Design Basis Accidents at Pressurized-Water Reactors. Additionally, in accordance with the provisions of 10 CFR 50.12, Specific exemptions, the licensee requested exemptions from certain requirements of 10 CFR 50.46(a)(1), and Appendix A, General Design Criteria for Nuclear Power Plants, to 10 CFR Part 50, specifically General Design Criterion (GDC) 35, Emergency core cooling, GDC 38, Containment heat removal, and GDC 41, Containment atmosphere cleanup.

The purpose of this letter is to provide the results of the U.S. Nuclear Regulatory Commission (NRC) staffs acceptance review of this amendment request and regulatory exemptions. The acceptance review was performed to determine if there is sufficient technical information in scope and depth to allow the NRC staff to complete its detailed technical review. The acceptance review is also intended to identify whether the application has any readily apparent information insufficiencies in its characterization of the regulatory requirements or the licensing basis of the plant.

Consistent with 10 CFR 50.90, an application for an amendment to a license (including the technical specifications) must fully describe the changes requested, and following as far as applicable, the form prescribed for original applications. Section 50.34 of 10 CFR addresses the content of technical information required. This section stipulates

that the submittal address the design and operating characteristics, unusual or novel design features, and principal safety considerations.

Consistent with 10 CFR 50.12, the Commission may, upon application by any interested person or upon its own initiative, grant exemptions from the requirements of the regulations of this part, which are authorized by law, will not present an undue risk to the public health and safety, and are consistent with the common defense, and security. The Commission will not consider granting an exemption unless special circumstances are present, as specified in Section 50.12(a)(2).

The NRC staff has reviewed your application and concluded that the information delineated in the enclosure to this letter is necessary to enable the staff to make an independent assessment regarding the acceptability of the proposed amendment request and exemptions in terms of regulatory requirements for the protection of public health and safety and the environment.

In order to make the license amendment and regulatory exemptions application complete, the NRC staff requests that the licensee supplement the application to address the information requested in the enclosure by May 27, 2021. This will enable the NRC staff to begin its detailed technical review. If the information responsive to the NRC staffs request is not received by the above date, the application will not be accepted for review pursuant to 10 CFR 2.101, and the NRC will cease its activities associated with the application. If the application is subsequently accepted for review, you will be advised of any further information needed to support the NRC staffs detailed technical review by separate correspondence.

The information requested and associated timeframe in this letter were discussed with Mr. Thomas Elwood of your staff on May 10, 2021.

If you have any questions regarding this matter, please contact me at 301-415-8371, or Mahesh.Chawla@nrc.gov.

Sincerely,

/RA/

Mahesh L. Chawla, Project Manager Plant Licensing Branch IV Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-483

Enclosure:

Supplemental Information Needed cc: Listserv

Enclosure SUPPLEMENTAL INFORMATION NEEDED LICENSE AMENDMENT REQUEST AND REGULATORY EXEMPTIONS FOR A RISK-INFORMED APPROACH TO ADDRESS GSI-191 AND RESPOND TO GL 2004-02 UNION ELECTRIC COMPANY CALLAWAY PLANT, UNIT NO. 1 DOCKET NO. 50-483 By letter dated March 31, 2021 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML21090A184), Union Electric Company (dba Ameren Missouri, the licensee), pursuant to Title 10 of the Code of Federal Regulations (10 CFR)

Section 50.90, Application for amendment of license, construction permit, or early site permit, requested an amendment for the licensees final resolution to addressing the concerns of Generic Safety Issue (GSI)-191, Assessment of Debris Accumulation on PWR

[Pressurized-Water Reactor] Sump Performance, and for responding to Generic Letter (GL) 2004-02, Potential Impact of Debris Blockage on Emergency Recirculation During Design Basis Accidents at Pressurized-Water Reactors. Additionally, in accordance with the provisions of 10 CFR 50.12, Specific exemptions, the licensee requested exemptions from certain requirements of 10 CFR 50.46(a)(1), and Appendix A, General Design Criteria for Nuclear Power Plants, to 10 CFR Part 50, specifically General Design Criterion (GDC) 35, Emergency core cooling, GDC 38, Containment heat removal, and GDC 41, Containment atmosphere cleanup.

REGULATORY BASIS Title 10 of the Code of Federal Regulations (10 CFR) Section 50.46, Acceptance criteria for emergency core cooling systems for light-water nuclear power reactors, requires that plants are able maintain adequate long-term core cooling to ensure that the fuel in the core can be cooled and maintained in a safe and stable configuration following a postulated accident.

GL 2004-02, Potential Impact of Debris Blockage on Emergency Recirculation During Design Basis Accidents at Pressurized-Water Reactors, requested that licensees provide information confirming that their plants are in compliance with the regulation. During its acceptance review of the licensees license amendment request and exemptions, the U.S. Nuclear Regulatory Commission (NRC) staff identified that it required additional information to confirm the licensees evaluation. The required information is identified below.

SUPPLEMENTAL INFORMATION NEEDED The licensee did not provide the information required for the NRC staff to complete its review of the in-vessel area. Items specifically requested in the in-vessel guidance, U.S. Nuclear Regulatory Commission Staff Review Guidance for In-Vessel Downstream Effects Supporting Review of Generic Letter 2004-02 Responses (ADAMS Accession No. ML19228A011), are not included in the submittal. Please include the following missing information:

a. Identify which test group number represents the Callaway-specific chemical effects test in WCAP-17788-P, Volume 5, Comprehensive Analysis and Test Program for GSl-191

Closure (PA-SEE-1090) - Autoclave Chemical effects Testing for GSI-191 Long Term Cooling;

b. Fuel design;

c. Details on the method used to calculate the debris amount at the core inlet (how was the time dependent filtration function developed, and why it is acceptable compared to the WCAP-17788 filtration method);

d. An evaluation of chemical effects timing vs. hot-leg switchover timing (it appears that chemicals may occur at 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and hot-leg switchover is at 13 hours1.50463e-4 days <br />0.00361 hours <br />2.149471e-5 weeks <br />4.9465e-6 months <br />, which requires additional evaluation);

e. Alternate flowpath resistance comparison between the plant and the WCAP-17788 model;

f.

Minimum emergency core cooling system flow per fuel assembly.

ML21130A588

• by e-mail OFFICE NRR/DORL/LPL4/PM* NRR/DORL/LPL4/LA* NRR/DSS/STSB/BC*

NRR/DEX/ESEB/BC NAME MChawla PBlechman VCusumano JColaccino DATE 5/11/2021 5/11/2021 5/10/2021 5/10/2021 OFFICE NRR/DNRL/NCSG/BC* NRR/DORL/LPL4/BC* NRR/DORL/LPL4/PM*

NAME SBloom JDixon-Herrity MChawla DATE 5/10/2021 5/11/2021 5/11/2021