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§ 50.62 10 CFR Ch. I (1–1–12 Edition)

§ 50.62 Requirements for reduction of (4) Each boiling reactor must risk from anticipated transients have a standby liquid control system without (ATWS) events for (SLCS) with the capability of injecting light-water-cooled into the a bo- . rated water solution at such a flow (a) Applicability. The requirements of rate, level of boron concentration and this section apply to all commercial boron-10 isotope enrichment, and ac- light-water-cooled nuclear power counting for reactor pressure vessel plants, other than nuclear power reac- volume, that the resulting reactivity tor facilities for which the certifi- control is at least equivalent to that cations required under § 50.82(a)(1) have resulting from injection of 86 gallons been submitted. per minute of 13 weight percent sodium (b) Definition. For purposes of this pentaborate decahydrate solution at section, Anticipated Transient Without the natural boron-10 isotope abundance Scram (ATWS) means an anticipated into a 251-inch inside diameter reactor operational occurrence as defined in pressure vessel for a given core design. appendix A of this part followed by the The SLCS and its injection location failure of the reactor trip portion of must be designed to perform its func- the protection system specified in Gen- tion in a reliable manner. The SLCS eral Design Criterion 20 of appendix A initiation must be automatic and must of this part. be designed to perform its function in a (c) Requirements. (1) Each pressurized reliable manner for plants granted a water reactor must have equipment construction permit after July 26, 1984, from sensor output to final actuation and for plants granted a construction device, that is diverse from the reactor permit prior to July 26, 1984, that have trip system, to automatically initiate already been designed and built to in- the auxiliary (or emergency) feedwater clude this feature. system and initiate a turbine trip (5) Each must under conditions indicative of an have equipment to trip the reactor ATWS. This equipment must be de- recirculating pumps automati- signed to perform its function in a reli- cally under conditions indicative of an able manner and be independent (from ATWS. This equipment must be de- sensor output to the final actuation de- signed to perform its function in a reli- vice) from the existing reactor trip sys- able manner. tem. (6) Information sufficient to dem- (2) Each pressurized water reactor onstrate to the Commission the ade- manufactured by Combustion Engi- quacy of items in paragraphs (c)(1) neering or by Babcock and Wilcox must through (c)(5) of this section shall be have a diverse scram system from the submitted to the Commission as speci- sensor output to interruption of power fied in § 50.4. to the control rods. This scram system (d) Implementation. For each light- must be designed to perform its func- water-cooled nuclear power oper- tion in a reliable manner and be inde- ating license issued before September pendent from the existing reactor trip 27, 2007, by 180 days after the issuance system (from sensor output to inter- of the QA guidance for non-safety re- ruption of power to the control rods). lated components, each licensee shall (3) Each boiling water reactor must develop and submit to the Commission, have an alternate rod injection (ARI) as specified in § 50.4, a proposed sched- system that is diverse (from the reac- ule for meeting the requirements of tor trip system) from sensor output to paragraphs (c)(1) through (c)(5) of this the final actuation device. The ARI section. Each shall include an expla- system must have redundant scram air nation of the schedule along with a jus- header exhaust valves. The ARI must tification if the schedule calls for final be designed to perform its function in a implementation later than the second reliable manner and be independent refueling outage after July 26, 1984, or (from the existing reactor trip system) the date of issuance of a license au- from sensor output to the final actu- thorizing operation above 5 percent of ation device. full power. A final schedule shall then

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be mutually agreed upon by the Com- (b) Limitation of scope. Paragraph (c) mission and licensee. For each light- of this section does not apply to those water-cooled nuclear power plant oper- plants licensed to operate prior to July ating license application submitted 21, 1988, if the capability to withstand after September 27, 2007, the applicant station blackout was specifically ad- shall submit information in its final dressed in the operating license pro- safety analysis report demonstrating ceeding and was explicitly approved by how it will comply with paragraphs the NRC. (c)(1) through (c)(5) of this section. (c) Implementation—(1) Information Submittal. For each light-water-cooled [49 FR 26044, June 26, 1984; 49 FR 27736, July 6, 1984, as amended at 51 FR 40310, Nov. 6, nuclear power plant licensed to operate 1986; 54 FR 13362, Apr. 3, 1989; 61 FR 39301, on or before July 21, 1988, the licensee July 29, 1996; 72 FR 49500, Aug. 28, 2007] shall submit the information defined below to the Director of the Office of § 50.63 Loss of all alternating current Regulation by April power. 17, 1989. For each light-water-cooled (a) Requirements. (1) Each light-water- nuclear power plant licensed to operate cooled nuclear power plant licensed to after July 21, 1988, but before Sep- operate under this part, each light- tember 27, 2007, the licensee shall sub- water-cooled nuclear power plant li- mit the information defined in this sec- censed under subpart C of 10 CFR part tion to the Director of the Office of Nu- 52 after the Commission makes the clear Reactor Regulation, by 270 days finding under § 52.103(g) of this chapter, after the date of license issuance. For and each design for a light-water- each light-water-cooled nuclear power cooled nuclear power plant approved plant operating license application under a standard design approval, submitted after September 27, 2007, the standard design certification, and man- applicant shall submit the information ufacturing license under part 52 of this defined below in its final safety anal- chapter must be able to withstand for a ysis report. specified duration and recover from a (i) A proposed station blackout dura- station blackout as defined in § 50.2. tion to be used in determining compli- The specified station blackout dura- ance with paragraph (a) of this section, tion shall be based on the following including a justification for the selec- factors: tion based on the four factors identi- (i) The redundancy of the onsite fied in paragraph (a) of this section; emergency sources; (ii) A description of the procedures (ii) The reliability of the onsite that will be implemented for station emergency ac power sources; blackout events for the duration deter- (iii) The expected frequency of loss of mined in paragraph (c)(1)(i) of this sec- offsite power; and tion and for recovery therefrom; and (iv) The probable time needed to re- (iii) A list of modifications to equip- store offsite power. ment and associated procedures, if any, (2) The reactor core and associated necessary to meet the requirements of coolant, control, and protection sys- paragraph (a) of this section, for the tems, including station batteries and specified station blackout duration de- any other necessary support systems, termined in paragraph (c)(1)(i) of this must provide sufficient capacity and section, and a proposed schedule for capability to ensure that the core is implementing the stated modifica- cooled and appropriate containment in- tions. tegrity is maintained in the event of a (2) Alternate ac source: The alternate station blackout for the specified dura- ac power source(s), as defined in § 50.2, tion. The capability for coping with a will constitute acceptable capability to station blackout of specified duration withstand station blackout provided an shall be determined by an appropriate analysis is performed which dem- coping analysis. Licensees are expected onstrates that the plant has this capa- to have the baseline assumptions, anal- bility from onset of the station black- yses, and related information used in out until the alternate ac source(s) and their coping evaluations available for required shutdown equipment are NRC review. started and lined up to operate. The

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