ML17333A123

Us Dept of Commerce, National Institute of Standards & Technology (NIST) - Supplement for Request for Changes to Nbsr Technical Specifications to Allow Low Power Testing

ML17333A123
Person / Time
Site:	National Bureau of Standards Reactor
Issue date:	11/20/2017
From:	Dimeo R US Dept of Commerce, National Institute of Standards & Technology (NIST)
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
Download: ML17333A123 (4)

Text

UNITED STATES DEPARTMENT OF COMMERCE National Institute cf Standards and Technclcgy Gaithersburg, Maryland 20888-November 20, 2017 Document Control Desk

• U.S. Nudear Regulatory Commission Washington, DC 20555-0001

Subject:

Supplement for request for changes to NBSR Technical Specifications to allow low power testing.

Ref: Docket 50-184, TR-5 Facility License Sirs/Madams:

On November 17, 2017, NCNR sent a response to a request for additional information regarding our license amendment request of March 2, 2017, and subsequent changes to three technical specifications. After discussions with NRC staff, we are requesting changes to technical specifications 3 .1.3 and 3 .3 .2, and elimination of the proposed 1.3 .31. Attached is a copy of the Technical Specification pages to be changed, with change bars.

Please contact Dr. Thomas Newton at (301) 975-6260, if you have any questions.

Robert Dimeo, Director NIST Center for Neutron Research I declare under penalty of perjury that the foregoing is true and correct.

Executed on November 20, 2017 nu[\;,

By: -~~=-"<..::..9--bl-¥-.::.=._--=---------

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1.3.30 Shutdown Margin The minimum shutdown reactivity necessary to provide confidence that the reactor can beshutdown by meansofthecontro 1and safely systems starting from any permissible operating condition, with the most reactive shim arm iri the most reactive position and the regulating rod fully withdrawn, and that the reactor will remain shutdown without further operator action.

1.3 .31 Surveillance Activities Those tests, checks and calibrations done to predict the operability of the equipment described in Section 4.0.

1.3 .32 Surveillance Intervals Maximum intervals are established to provide operational flexibility and not to reduce frequency. Established frequencies shall be maintained over the long term. The surveillance interval is the time between a check, test or calibration, whichever is appropriate to the item being subjected to the surveillance, and is measured from the date of the last surveillance. Surveillance intervals are:

(a) Five Year Interval not to exceed six years.

(b) Biennial Interval not to exceed two and one-half years.

(c) Annual Interval not to exceed 15 months.

(d) Semi-annual Interval not to exceed seven and a half months.

(e) Quarterly Interval not to exceed four months.

( :f) Monthly Interval not to exceed six weeks.

(g) Weekly Interval not to exceed ten days.

1.3.33 Unscheduled Shutdown Any unplanned shutdown o*f the reactor caused by actuation of the reactor safety system, operator error, equipment malfunction, or a manual shutdown in response to conditions that could adversely affect safe operation, not including shutdowns that occur during testing or equipment operability check 10

(1) An excess reactivity limit provides adequate excess reactivity to override the xenon buildup and to overcome the temperature change in going from zero power to 20 MW, without affecting the required shutdown margin. In addition, the maximum reactivity insertion accident at startup, which assumes the insertion of 0.5% Lip into a critical core, is not affected by the total core excess reactivity.

(2) These specifications ensure that the reactor can be put into a shutdown condition from any operating condition and remain shutdown even if the maximumworthshimarmshouldstickinthefullywithdrawnposition with the regulating rod also fully withdrawn.

3.1.3 Core Configuration Applicability: Core grid positions Objective: To ensure that effective fuel cooling is maintained during forced flow reactor operation.

Specification The reactor shall not operate unless all grid positions are filled with full length fuel elements or thimbles, except during subcritical and critical startup testing with natural convection flow.

Core grid positions shall be filled to prevent coolant flow from bypassing the fuel elements for operation of the reactor with forced coolant flow.

3.1.4 Fuel Burnup Applicability: Fuel Objective: To remain within allowable limits of bumup 14

effectiveness of the moderator dump or approach to critical for a previously unmeasured core loading, it is necessary to operate the reactor without restriction on reactor vessel level. This is permissible under conditions when forced reactor cooling flow is not required, such as is permitted in the specifications of Section 2.2( 4).

(2) Deuterium gas will collect in the helium cover gas system because of radiolytic disassociation of D20. Damage to the primary system could occur if this gas were to reach an explosive concentration (about 7.8% by volume at 77°F (25°C) in helium if mixed with air). To ensure a substantial margin below the lowest potentially explosive value, a 4% limit is imposed.

(3) Materials ofconstruction, being primarily low activation alloys and stainless steel, are chemically compatible with the primary coolant. The stainless steel pumps are heavy walled members and are in areas of low stress, so they should not be susceptible to chemical attack or stress corrosion failures. A failure of the gaskets or valve bellows would not result in catastrophic failure of the primary system. Other materials should be compatible so as not to cause a loss of material and system integrity.

3 .3 .2 Emergency Core Cooling Applicability: Emergency Core Cooling System Objective: To ensure an emergency supply of coolant.

Specifications The reactor shall not be operated, except during subcritical and critical startup testing with natural convection flow, unless:

(1) The D20 emergency core cooling system is operable.

(2) A source of makeup water to the D20 emergency cooling tank is available.

(1) In the event of a loss of core coolant, the emergency core cooling system provides adequate protection against melting of the reactor core and associated release of fission products.

(2) The emergency core cooling system employs one sump pump to return spilled coolant to the overhead storage tank. Because only one sump pump is used, it must be operational whenever the reactor is operational. There is sufficient D20 available to provide approximately 2.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> of cooling on a once-through basis. In the event that the sump pump fails and the D20 18