10 CFR 50.68, Criticality Accident Requirements

Criticality accident requirements

a

(a) Each holder of a construction permit or operating license for a nuclear power reactor issued under this part or a combined license for a nuclear power reactor issued under Part 52 of this chapter, shall comply with either 10 CFR 70.24 of this chapter or the requirements in paragraph (b) of this section.

b

(b) Each licensee shall comply with the following requirements in lieu of maintaining a monitoring system capable of detecting a criticality as described in 10 CFR 70.24:

(1) Plant procedures shall prohibit the handling and storage at any one time of more fuel assemblies than have been determined to be safely subcritical under the most adverse moderation conditions feasible by unborated water.

(2) The estimated ratio of neutron production to neutron absorption and leakage (k-effective) of the fresh fuel in the fresh fuel storage racks shall be calculated assuming the racks are loaded with fuel of the maximum fuel assembly reactivity and flooded with unborated water and must not exceed 0.95, at a 95 percent probability, 95 percent confidence level. This evaluation need not be performed if administrative controls and/or design features prevent such flooding or if fresh fuel storage racks are not used.

(3) If optimum moderation of fresh fuel in the fresh fuel storage racks occurs when the racks are assumed to be loaded with fuel of the maximum fuel assembly reactivity and filled with low-density hydrogenous fluid, the k-effective corresponding to this optimum moderation must not exceed 0.98, at a 95 percent probability, 95 percent confidence level. This evaluation need not be performed if administrative controls and/or design features prevent such moderation or if fresh fuel storage racks are not used.

(4) If no credit for soluble boron is taken, the k-effective of the spent fuel storage racks loaded with fuel of the maximum fuel assembly reactivity must not exceed 0.95, at a 95 percent probability, 95 percent confidence level, if flooded with unborated water. If credit is taken for soluble boron, the k-effective of the spent fuel storage racks loaded with fuel of the maximum fuel assembly reactivity must not exceed 0.95, at a 95 percent probability, 95 percent confidence level, if flooded with borated water, and the k-effective must remain below 1.0 (subcritical), at a 95 percent probability, 95 percent confidence level, if flooded with unborated water.

(5) The quantity of SNM, other than nuclear fuel stored onsite, is less than the quantity necessary for a critical mass.

(6) Radiation monitors are provided in storage and associated handling areas when fuel is present to detect excessive radiation levels and to initiate appropriate safety actions.

(7) The maximum nominal U-235 enrichment of the fresh fuel assemblies is limited to five (5.0) percent by weight.

(8) The FSAR is amended no later than the next update which § 50.71(e) of this part requires, indicating that the licensee has chosen to comply with § 50.68(b).

c

(c) While a spent fuel transportation package approved under Part 71 of this chapter or spent fuel storage cask approved under Part 72 of this chapter is in the spent fuel pool:

(1) The requirements in § 50.68(b) do not apply to the fuel located within that package or cask; and

(2) The requirements in Part 71 or 72 of this chapter, as applicable, and the requirements of the Certificate of Compliance for that package or cask, apply to the fuel within that package or cask.

Federal Register

[[[FR::http://frwebgate.access.gpo.gov/cgi-bin/getpage.cgi?dbname=1998_register&page=63130&position=1%7C 63 FR 63130, Nov. 12, 1998]]; as amended at [[FR::http://frwebgate.access.gpo.gov/cgi-bin/getpage.cgi?dbname=2006_register&page=66648&position=1%7C 71 FR 66648, Nov. 16, 2006]]]

External Links

[[URL::http://www.nrc.gov/reading-rm/doc-collections/cfr/part050/part050-0068.html%7CNRC website 10 CFR 50.68]]

v t e Code of Federal Regulations
Title 10 Part 50 - DOMESTIC LICENSING OF PRODUCTION AND UTILIZATION FACILITIES
10 CFR: 1 2 4 5 7 9 10 11 12 13 14 15 16 19 20 21 25 26 30 31 32 33 34 35 36 37 39 40 50 51 52 54 55 60 61 62 63 70 71 72 73 74 75 76 81 95 100 140 150 160 170 171
1, General Provisions, Basis, purpose, and procedures applicable 2, Definitions 3, Interpretations 4, Written communications 5, Deliberate misconduct 7, Employee protection 8, Information collection requirements: OMB approval 9, Completeness and accuracy of information 10, Requirement of License, Exceptions, License required; limited work authorization 11, Exceptions and exemptions from licensing requirements 12, Specific exemptions 13, Attacks and destructive acts by enemies of the United States; and defense activities 20, Classification and Description of Licenses, Two classes of licenses 21, Class 104 licenses; for medical therapy and research and development facilities 22, Class 103 licenses; for commercial and industrial facilities 23, Construction permits 30, Applications for Licenses, Certifications, and Regulatory Approvals; Form; Contents; Ineligibility of Certain Applicants, Filing of application for licenses; oath or affirmation 31, Combining applications 32, Elimination of repetition 33, Contents of applications; general information 34, Contents of applications; technical information 36, Technical specifications 37, Agreement limiting access to Classified Information 38, Ineligibility of certain applicants 39, Public inspection of applications 40, Standards for Licenses, Certifications, and Regulatory Approvals, Common standards 41, Additional standards for class 104 licenses 42, Additional standard for class 103 licenses 43, Additional standards and provisions affecting class 103 licenses and certifications for commercial power 44, Combustible gas control for nuclear power reactors 45, Standards for construction permits, operating licenses, and combined licenses 46, Acceptance criteria for emergency core cooling systems for light-water nuclear power reactors 47, Emergency plans 48, Fire protection 49, Environmental qualification of electric equipment important to safety for nuclear power plants 50, Issuance, Limitations, and Conditions of Licenses and Construction Permits, Issuance of licenses and construction permits 51, Continuation of license 52, Combining licenses 53, Jurisdictional limitations 54, Conditions of licenses 55, Conditions of construction permits, early site permits, combined licenses, and manufacturing licenses 56, Conversion of construction permit to license; or amendment of license 57, Issuance of operating license 58, Hearings and report of the Advisory Committee on Reactor Safeguards 59, Changes, tests and experiments 60, Acceptance criteria for fracture prevention measures for lightwater nuclear power reactors for normal operation 61, Fracture toughness requirements for protection against pressurized thermal shock events 62, Requirements for reduction of risk from anticipated transients without scram (ATWS) events for light-water-cooled nuclear power plants 63, Loss of all alternating current power 64, Limitations on the use of highly enriched uranium (HEU) in domestic non-power reactors 65, Requirements for monitoring the effectiveness of maintenance at nuclear power plants 66, Requirements for thermal annealing of the reactor pressure vessel 67, Accident source term 68, Criticality accident requirements 69, Inspections, Records, Reports, Notifications, Risk-informed categorization and treatment of structures, systems and components for nuclear power reactors 70, Inspections 71, Maintenance of records, making of reports 72, Immediate notification requirements for operating nuclear power reactors 73, Licensee event report system 74, Notification of change in operator or senior operator status 75, Reporting and recordkeeping for decommissioning planning 76, . Licensee's change of status; financial qualifications 78, US/IAEA Safeguards Agreement, Facility information and verification 80, Transfers of Licenses--Creditors' Rights--Surrender of Licenses, Transfer of licenses 81, Creditor regulations 82, Termination of license 83, Release of part of a power reactor facility or site for unrestricted use 90, Amendment of License or Construction Permit at Request of Holder, Application for amendment of license, construction permit, or early site permit 91, Notice for public comment; State consultation 92, Issuance of amendment 100, Revocation, Suspension, Modification, Amendment of Licenses and Construction Permits, Emergency Operations by the Commission, Revocation, suspension, modification of licenses, permits, and approvals for cause 101, Retaking possession of special nuclear material 102, Commission order for operation after revocation 103, Suspension and operation in war or national emergency 109, Backfitting 110, Enforcement, Violations 111, Criminal penalties 120, Additional Standards for Licenses, Certifications, and Regulatory Approvals, Training and qualification of nuclear power plant personnel 150, Aircraft impact assessment Appendices: 10 CFR 50 Appendix A, Appendix a to Part 50-General Design Criteria for Nuclear Power Plants 10 CFR 50 Appendix B, Quality Assurance Criteria for Nuclear Power Plants and Fuel Reprocessing Plants 10 CFR 50 Appendix C, Appendix C to Part 50-A Guide for the Financial Data and Related Information Required to Establish Financial Qualifications for Construction Permits and Combined Licenses 10 CFR 50 Appendix D, Appendix D to Part 50--Reserved 10 CFR 50 Appendix E, Appendix E to Part 50-Emergency Planning and Preparedness for Production and Utilization Facilities 10 CFR 50 Appendix F, Appendix F to Part 50--Policy Relating to the Siting of Fuel Reprocessing Plants and Related Waste Management Facilities 10 CFR 50 Appendix G, Appendix G to Part 50-Fracture Toughness Requirements 10 CFR 50 Appendix H, Appendix H to Part 50-Reactor Vessel Material Surveillance Program Requirements 10 CFR 50 Appendix I, Appendix I to Part 50-Numerical Guides for Design Objectives and Limiting Conditions for Operation to Meet the Criterion "As Low As Is Reasonably Achievable" for Radioactive Material In Light-Water-Cooled Nuclear Power Reactor E 10 CFR 50 Appendix J, Appendix J to Part 50-Primary Reactor Containment Leakage Testing for Water-Cooled Power Reactors 10 CFR 50 Appendix K, Appendix K to Part 50-Eccs Evaluation Models 10 CFR 50 Appendix L, Appendix L to Part 50--Reserved 10 CFR 50 Appendix M, Appendix M to Part 50--Reserved 10 CFR 50 Appendix N, Appendix N to Part 50-Standardization of Nuclear Power Plant Designs: Permits to Construct and Licenses to Operate Nuclear Power Reactors of Identical Design At Multiple Sites 10 CFR 50 Appendix O, Appendix O to Part 50-Reserved 10 CFR 50 Appendix P, Appendix P to Part 50--Reserved 10 CFR 50 Appendix Q, Appendix Q to Part 50--Pre-Application Early Review of Site Suitability Issues 10 CFR 50 Appendix R, Appendix R to Part 50-Fire Protection Program for Nuclear Power Facilities Operating Prior to January 1, 1979 10 CFR 50 Appendix S, General Information

10 CFR 50.68, Criticality Accident Requirements

a

b

c

Federal Register

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