ML17335A369

Supplemental Information National Institute of Standards and Technology Request for Additional Information of License Amendment Request for the Renewed Facility License No. R-5 for the National Bureau of Standards Test Reactor

ML17335A369
Person / Time
Site:	National Bureau of Standards Reactor
Issue date:	12/01/2017
From:	Dimeo R M US Dept of Commerce, National Institute of Standards & Technology (NIST)
To:	Document Control Desk, Office of Nuclear Reactor Regulation
Yin X, NRR/DLP, 415-1404
References
CAC 000955
Download: ML17335A369 (3)

Text

December 1, 2017 Document Control Desk U.S. Nuclear Regulatory Commission Washington, DC 20555-0001 UNiTECI STATES IJEFIARTMENT OF COMMERCE National Institute of Standards and Technology Gaitheroburg, Maryland 20888-

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 20, 2017. NCNR sent a request for subsequent changes regarding our license amendment request of March 2, 2017. Afl:cr discussions with NRC staff. we are requesting additional changes to technical specifications 3.3.1 and 3.3.2. 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.

Respectfully, WM.~ Robert M. Dimeo, Director NIST Center for Neutron Research 100 Bureau Drive, MS 6100 Bldg. 235, Room K 107 Gaithersburg, MD 20899 I declare under penalty of perjury that the foregoing is true and correct. Rxecuted on December 1, 2017 By:~M.0;-.. cc: Xiaosong Yin, BRR/DPR/PRLB NlSI The nuclear and process channels of Table 3.2.2 initiate protective action to Ensure that the safety limit is not exceeded.

With these channels operable, the safety system has redundancy.

3 .3 Coolant System 3 .3 .1 Primary and Secondary Applicability:

Primary fluid systems Objective:

To prevent degradation of primary systems' materials.

Specifications The reactor shall not be operated unless: ( 1) The reactor vessel coolant level is no more than 25 inches below the overflow standpipe.

Exception:

To perform periodic surveillance of the effectiveness of the moderator dump or approach to critical testing for a previously unmeasured core loading, it is necessary to operate the reactor as permitted in the specifications of Section 2.2(4) and without restriction on reactor vessel level above the top of the 6" overflow pipe (refueling level) (2) The D2 concentration in the Helium Sweep System shall not exceed 4% by volume. (3) All materials, including those of the reactor vessel, in contact with the primary coolant shall be compatible with the D 2 0 environment . . ! (1) The limiting value for reactor vessel coolant level is somewhat arbitrary because the core is in no danger so long as it is covered with water. However, a drop of vessel level indicates a malfunction of the reactor cooling system and possible approach to uncoyering the qore. Thus, a measurable value well above the mfoimum level is chosen i~ order to provide a generous margin of approximately 7 feet (2.13 m) above the fuel elements.

To permit periodic t~sting, such as surveillance of the effectiveness of the moderator dump or approach to criticaf for a previously unmeasured core loading, h is necessary to operate the reactor without restriction on reactor vessel level. This is permissible urider conditions when forced reactor cooling flow is not required, such as is permitted in.the specifications of Section 2.2( 4). i7 (2) Deuterium gas will collect in the helium cover gas system because of radiolytic disassociation of D 2 0. Damage to the primai;y 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 explo.sive value, a . . 4% limit is imposed. . . . . (3) Materials of construction, being pri~~rily low aqtivation 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. Othei* materials should be compatible so as not to cause a los~ 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 unless: (1) The D 2 0 emergency core cooling system is operable, except when operating under specification 2.2( 4) (2) A source of makeup water to the D 2 0 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.

Full operability is not available, nor is it needed, when operating as permitted by the specifications of Sections 2.2(4) and 33.1(1). However, the 3000 gallon D 2 0 emergency cooling tank and a source of makeup water would be available.

(2) The emergency core cooling system employs one sump pump to return spilled coolant to the overhead storage tank. Because only one sump p11mp is used, it must be operational whenever the reactor is operational.

There is sufficient D20 available to provide approximately

2.5 hour5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />s

of cooling on a once-through basis. In the event that the sump pump fails and the D20 supply in the overhead storage tank is exhausted, domestic water or a suitable alternative would be used to furnish water for once-through cooling. The water makeup capacity must be in excess of.25 gpm, which_ was found adequate in cooling calculations to prevent fuel damage. 18