ML25150A405

NIST - License Amendment Request

ML25150A405
Person / Time
Site:	National Bureau of Standards Reactor
Issue date:	05/28/2025
From:	US Dept of Commerce, National Institute of Standards & Technology (NIST)
To:	Office of Nuclear Reactor Regulation
Shared Package
ML25150A403	List: ML25150A404 ML25150A405
References
EPID L-2024-NFC-0000
Download: ML25150A405 (1)

Text

1 Determination of No Significant Hazard May 28, 2025 In the attached license amendment request, the NIST Center for Neutron Research (NCNR) requests an amendment to the facility license involving reclassification of the National Bureau of Standards Reactor (NBSR) from a testing facility to a research reactor. As required by 10 CFR 50.91(a), the following analysis is presented to show the proposed amendment does not create a significant hazard using the criteria of 10 CFR 50.92(c).

1. Does the proposed amendment involve a significant increase in the probability or consequences of an accident previously evaluated?

The proposed license amendment is only to change the classification of the NBSR from a testing facility to a research reactor using the updated criteria for a testing facility given in the Non-Power Production or Utilization Facility License Renewal Rule (EPID L-2024-NFC-0000).

There are no proposed changes in structures, systems, or components (SSCs), operating posture or power level and no proposed changes in effluent or accident analyses. Therefore, the license amendment will not involve a significant increase in the probability or consequences of an accident previously evaluated.

2. Does the proposed amendment create the possibility of a new or different kind of accident from any accident previously evaluated?

The proposed license amendment is only a classification change of the NBSR using the updated criteria given in the NPUF rule referred to above. There are no proposed changes in SSCs, operating posture or power level and no proposed changes in effluent or accident analyses.

Therefore, the proposed amendment for reclassification will not create the possibility of a new or different kind of accident from any accident previously evaluated.

3. Does the proposed amendment involve a significant reduction in a margin of safety?

The proposed license amendment is only to modify the NBSR facility classification. There are no changes in margin of safety criteria from reclassifying a testing facility to a research reactor.

As there are no proposed changes in SSCs, operating posture or power level and no proposed changes in effluent or accident analyses, the proposed amendment of reclassification does not involve a significant reduction in a margin of safety.

Request for Reclassi"cation of the NBSR On December 30, 2024, NRC implemented the Non-Power Production or Utilization Facility License Renewal Rule (EPID L-2024-NFC-0000). Among other things, this rule rede"ned the previous 50.2 de"nition of testing facility:

Testing facility - Testing facility means a non-power production or utilization facility that is a nuclear reactor licensed under § 50.21(c) or § 50.22 for which:

(1) Analyzed accident radiation doses are in excess of the dose criterion for facilities not subject to 10 CFR part 100 set forth in § 50.34(a)(1)(i); or (2) The Commission determines that the design, operation, or use and the associated risk warrant classification as a testing facility.

With this rule change, the National Bureau of Standards Reactor (NBSR) no longer meets the newly promulgated de"nition of a testing facility, for reasons given below. This letter is requesting a license amendment for the NRC to reclassify the NBSR as a research reactor, as in accordance with §50.2 Non-power reactor de"nition (2).

Justi"cation In addressing item (1) in the § 50.2 definition of Testing Facility:

50.34(a)(1)(i) states, in part:

. For non-power production or utilization facilities not subject to 10 CFR part 100, the assessment must provide an evaluation of the applicable radiological consequences that demonstrates with reasonable assurance that any individual located in the unrestricted area following the onset of a postulated accident, including consideration of experiments, would not receive a radiation dose in excess of 1 rem (0.01 Sv)2 TEDE for the duration of the accident.

The National Bureau of Standards Reactor (NBSR) Safety Analysis Report (SAR) section 13.2.1 describes the assessment of the radiological consequences of the Maximum Hypothetical Accident (MHA). The MHA is described in NUREG-1537, Guidelines for Preparing and Reviewing Applications for the Licensing of Non-Power Reactors, section 13.1.1 as, the most hazardous radiological accident conceivable at a non-power reactor.

The result of this analysis is summarized in the SAR Table 13.4, reproduced below. It shows

that the maximum dose to an individual located in the unrestricted area following the MHA is 6.4 mrem, less than 1% of the dose de"ning a testing facility in § 50.34(a)(1)(i) (1000 mrem).

Also, a detailed description of experiments and potential doses are provided in this document showing minimal dose consequences. Thus, the NBSR no longer meets the criterion speci"ed in § 50.2 de"nition of a testing facility, item (1).

Table 13.4: Dose to an Individual at the Edge of the 400-meter Exclusion Zone After the Maximum Hypothetical Accident Doses (in mrem) to a person standing at the edge of the exclusion zone (400m) 0-2 Hours 2-24 Hours 1-30 Days Total Radiation from fission product decay Direct 0.0 0.0 0.1 0.1 Sky Shine 0.0 0.0 0.2 0.2 Total 0.0 0.0 0.3 0.3 Iodine Releases CEDE1 0.0 0.0 0.0 0.0 Thyroid 0.0 0.1 0.0 0.1 Noble Gas Cloud (max)

Slightly Stable Conditions2 1.0 3.4 2.0 6.4 1 The dose given is the maximum Committed Effective Dose Equivalent (CEDE) at a point on or outside the 400 m boundary.

2 The wind speed is assumed constant at 1 m/s, with allowance for meandering (averaged over 120 min) but no wind shifts, Pasquill diffusion category E. The dose due to the cloud outside the boundary is then a maximum for this stability condition. However, such conditions could not persist for even 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />, so these numbers are large over-estimates. Actual doses would be 2-100 times lower.

In addressing item (2) in the § 50.2 de"nition of Testing Facility:

Although there is no guidance as to what risk warrants classi"cation as a testing facility other than those given in § 50.34(a)(1)(i), the NBSR is designed to be a low-risk facility for many reasons, including the following:

• The NBSR operates at low pressure, and low temperature, minimizing the potential for accidents.

• The NBSR's maximum power of 20 MW results in a relatively low inventory of fission products in the core, minimizing the consequences of an accident.

• As analyzed in NBSR SAR section 13.2.4, once the reactor is shut down, forced cooling is not needed to prevent fuel damage.

• The operations and use of the NBSR is primarily to support neutron beam research. The NBSR does not perform in-core irradiations of experimental fuels

of any kind or any other in-core experiments that could result in core damage or a reactivity accident. All experiments are required to meet technical specification requirements, designed to limit reactivity and eliminate the possibility of reactor damage.

Environmental Report This LAR also should be excluded from requiring an environmental review, as according to 10 CFR 51, the relevant categorical exclusions are as follows (regulations in italics, response in roman upright):

51.22.c(9):

Issuance of an amendment to a permit or license for a reactor under part 50 or part 52 of this chapter that changes a requirement or issuance of an exemption from a requirement, with respect to installation or use of a facility component located within the restricted area, as de"ned in part 20 of this chapter; or the issuance of an amendment to a permit or license for a reactor under part 50 or part 52 of this chapter that changes an inspection or a surveillance requirement; provided that:

(i) The amendment or exemption involves no signi"cant hazards consideration; As noted in the Finding of No Signi"cant Hazard accompanying this LAR, the conclusion was made that no signi"cant hazards exist.

(ii) There is no signi"cant change in the types or signi"cant increase in the amounts of any effluents that may be released offsite; and As there are no proposed changes in structures, systems, or components (SSCs), operating posture or power level, there will be no changes in the amounts of effluents.

(iii) There is no signi"cant increase in individual or cumulative occupational radiation exposure As there are no proposed changes in SSCs, operating posture, or power level, there will be no changes in an individual or cumulative occupational radiation exposure.

And under 51.22.c(10),

Issuance of an amendment to a permit or license issued under this chapter which (i) Changes surety, insurance and/or indemnity requirements; The license amendment does not change any surety, insurance, or indemnity requirements.

(ii) Changes recordkeeping, reporting, or administrative procedures or requirements;

The license amendment does not change any recordkeeping, reporting, or administrative procedures, above and beyond these given in the NPUF rule.

(iii) Changes the licensees or permit holders name, phone number, business or e-mail address; There are no changes in the licensees information.

(iv) Changes the name, position, or title of an officer of the licensee or permit holder, including but not limited to, the radiation safety officer or quality assurance manager; or There are no changes in personnel positions.

(v) Changes the format of the license or permit or otherwise makes editorial, corrective or other minor revisions, including the updating of NRC approved references.

Other than reclassi"cation of the license type under new requirements given in the NPUF rule, there are no changes in license format.

Status of Safety Analysis Report and Licensing Considerations This section provides an overview of recent changes to the NBSR Safety Analysis Report and License Amendment Requests.

The NBSR operated at 10 MWth until 1985, when it was upgraded to 20 MWth, and it has been operating since then. The most recent NRC license renewal for the NBSR was approved on April 22, 2009, which allowed the NBSR to operate for an additional 20 years, giving a new license expiration date of July 2, 2029. The NBSR operated without any major incidents since the renewal in 2009 until February 3, 2021, when the NBSR experienced a partial fuel melting incident due to one fuel element being improperly latched in the top grid plate during refueling. Site boundary doses resulting from the incident were a fraction of the MHA doses listed above. After the incident, the NBSR was shut down for an extended period of recovery until the NRC gave approval for the NBSR to restart on March 10, 2023.

February 3, 2021, Incident Pre-Incident An NBSR operation cycle typically lasts 38.5 days with a 10-day outage at the end of the cycle, after which another cycle begins. In each cycle, four fuel elements are removed from the core and replaced with fresh fuel elements during a shuffling of the fuel elements in the core (cycling them through various positions in the core based on their initial loading

position). This refueling and reshuffling is usually done during the 10-day outage between cycles. Typically, the 10-day outage is more than sufficient for the refueling and shuffling; however, this outage period is also used for maintenance and repair work and may be extended when needed.

Post-Incident The incident led to signi"cant overhaul of in safety culture, organization, and record-keeping among several other things. One major change at the NCNR is the prioritization and elevation of the Aging Reactor Management (ARM) program to their own team within the Reactor Operations and Engineering (ROE) group. This allowed for emphasizing oversight of communications between groups and ensuring that maintenance and other identi"ed issues are prioritized and resolved. A summary of root causes and recommended corrective actions are provided in the "nal report provided to the NCNR director (and forwarded to NRC) from the Safety Evaluation Committee (SEC), which was submitted to the NCNR director by a subcommittee of the SEC on August 12, 2021. The report is provided here:

https://www.nrc.gov/docs/ML2127/ML21274A021.pdf.

A complete list of the corrective actions that were completed prior to startup in March 2023 is provided here: https://www.nrc.gov/docs/ML2127/ML21274A025.pdf.

A list of corrective actions post-startup is provided here:

https://www.nrc.gov/docs/ML2127/ML21274A026.pdf.

At the forefront of improvements made post-incident is the adoption of a healthy nuclear safety culture, which addresses many of the prior cultural issues at the NCNR. Changes in culture are not instantaneous and take time to implement successfully, but the NCNR continues to strive to maintain an integrated nuclear safety culture. Additional improvements are primarily centered around improved operator training and quali"cations led by the reactor operations training program manager, as well as signi"cant improvements to the ARM program. This includes the development of the ARM group with a chief responsible for ensuring the reliability of the aging NBSR structures, systems, and components (SSCs).

Additionally, overhauls and improvements have been made to the Corrective Action Program (CAP), the observations program, and the development of a Quality Assurance (QA) group led by the Quality Assurance Program Manager (QAPM). Each of these changes is in a different stage of development. These ongoing changes have led to signi"cant improvements in the safe operation of the NBSR reactor.

As a result of the February 2021 fuel failure incident, three license amendments were made.

On July 21, 2022, the NRC issued Amendment No. 13 to the NBSR license that revised the Technical Speci"cations (TS) related to the latching veri"cation of fuel elements. Originally, TS required operators to perform one of the three methods, namely the elevation check,

rotational check, or visual inspection for latch veri"cation. The "rst amendment revised the TS to require a rotational check followed by a visual inspection. Even after extensive cleanup, there was potential fuel debris left in the NBSR primary systems. Hence, the second LAR, which was issued on February 1, 2023, as Amendment No. 14, evaluates the safety and operational impacts of such debris remaining within the primary system and allows for operation of the reactor with the unclad fuel debris present. The third LAR evaluates the use of a speci"c method to perform core loading analyses of the NBSR. This LAR, which was issued by the NRC as Amendment No. 15 on March 2, 2023, includes an engineering procedure and detailed analysis methods to evaluate Alternative Fuel Management Schemes (AFMS) core loadings for the NBSR. AFMS is any core loading that deviate from the nominal core loading scheme. All of these LAR changes concluded that there are no more than minimal changes to the accident analyses as found in the updated FSAR.

ML23040A340 NIST Restart Authorization TER (March 9, 2023) provides a detailed review of the aforementioned amendments and other changes in the facility operations to permit the restart of the facility.

Currently, License Amendment No. 16, submitted on December 19, 2024, is pending NRC review. NBSR Technical Speci"cations (Amendment 15, March 2, 2023) Table 3.2.2 and Table 4.2.2 might (inadvertently) permit operations of the NBSR when either one of the inner or outer plenum "ow channels is bypassed. License Amendment Request 16 requested to modify NBSR Technical Speci"cations 3.2.2 and 4.2.2 to require that both inner and outer plenum "ow channels be operable during reactor operations.

All accidents analyzed in the NBSR Safety Analysis Report (SAR) are bounded by the MHA, and there are no other postulated accidents that would affect reclassi"cation (all have a lower potential off-site dose). Thus, no changes were necessary to the previously evaluated accidents as described in the SAR.

Engineered safety features (ESFs) that affect the MHA are limited to the Con"nement building, ventilation, and effluent monitors. No postulated changes to these ESFs or any action level setpoint are proposed, and no changes are being proposed to the 400-meter boundary, so the resultant dose from the MHA remains unaffected.

A review of the NBSR Technical Speci"cations has revealed that there are no references to testing facilities, so no technical or editorial changes are needed.

Changing the license from a testing facility to a research reactor will not change any emergency response requirements, the NBSR Emergency Plan, or the NCNR Physical Security Plan.

Safety Review of NCNR Facility, Research Activities, and Experiments The NCNR is a national user facility, offering in-core irradiation, thermal, and cold neutron beam instrumentation for use by all quali"ed applicants. Therefore, excluding the NBSR, the primary radiological hazards at NCNR stem from neutron sources, radiological laboratories, and irradiated materials handling areas. This section describes existing experiments, laboratories, research, and other support activities and their bounding safety evaluations.

The NCNRs neutron source provides the intense, conditioned beams of neutrons required for these types of measurements. In addition to the thermal neutron beams from the heavy water moderator, the NCNR has two liquid hydrogen moderators, or cold sources, which supply neutrons to three-fourths of the instruments. One is a large area moderator and the other is smaller, but with high brightness. These moderators provide long-wavelength guided neutron beams for industrial, government, and academic researchers. There are currently 30 experiment stations: 12 are used for neutron physics, analytical chemistry, or imaging, and 18 are beam facilities for neutron scattering research. More complete descriptions can be found at https://www.nist.gov/ncnr/neutron-instruments.

Radiological hazards within the NCNR include:

1. Neutron Exposure from Cold and Thermal Neutron Sources The NCNR operates neutron beamlines and guides that transport neutrons from the reactor to various experimental stations. The size of neutron beams at the NBSR typically range from a few mm2 to 200 cm2. Beams with an in-beam dose rate in excess of 100 mrem/hr and accessible (have an open path in excess of 30 cm) are designated and controlled as High Radiation Areas.

2. Gamma Radiation from Activated Components Experimental setups utilizing neutron sources may cause activation of structural materials and experimental samples. This material is stored in restricted areas where access and dose rates are controlled to limit personnel exposure. Routine surveys are performed and any changes in equipment is evaluated before being implemented.

3. Radioactive Sample Handling and Contamination Risks NBSR also has in-core irradiation capabilities. Neutron activation analysis (NAA) and other radiochemistry experiments involve irradiating materials to induce radioactivity.

Experiments utilizing these facilities are highly variable. All elements of the activity, facility usage, disposal, and potential personnel exposures are addressed by technical review and administrative authorization processes. Holding the source in a shielded con"guration to allow sufficient decay prior to direct manipulation, processing, or analysis is the primary

ALARA technique used in these situations. Each proposed experimental procedure is carefully reviewed by the Beam Experimental Subcommittee a subcommittee of the SEC. As work is performed, it is evaluated by health physics who assist in conducting exposure measurements and conducting contamination surveys as appropriate.

4. Waste Handling and Storage In addition to the waste generate from reactor operations, the NBSR generates low-level radioactive waste from experiments and sample preparations. Handling of activated equipment and components requires strict adherence to radiation safety protocols. The NBSR has a robust program for collecting, characterizing, storing, and properly disposing of radiation wastes.

5. Radiation from Calibration and Standardization Sources NCNR maintains radioactive sources for the calibration of detectors and instruments.

Procedures, training, shielding, interlocks, and controlled access areas mitigate these hazards.

Mitigation Measures Shielding: Use of lead, concrete, and borated polyethylene to reduce exposure to neutron and gamma radiation.

Remote Handling of activated materials to minimize direct exposure.

Radiation Monitoring: Use of dosimeters, area radiation monitors, and contamination surveys.

Ventilation Systems: Controlled air handling to prevent airborne contamination.

Training and Procedures: Strict protocols for handling radioactive materials and responding to spills or exposures.

The average annual dose for all NCNR personnel is approximately 15 mrem/year (2023). All experimental activities are reviewed by the NCNR Safety Evaluation Committee prior to approval. NBSR updated FSAR Chapter 11 provides an overall view of the radiation sources, existing radiation program, ALARA, radiation monitoring and surveying, radiation exposure control and dosimetry, environmental monitoring, and radioactive waste management. All personnel who work around radioactive materials are monitored using either a National Voluntary Laboratory Accreditation Program (NVLAP) dosimeter or an electronic dosimeter.

Doses are monitored on a quarterly basis, and any abnormal exposures are promptly investigated.

FSAR 11.1.7 Environmental Monitoring The NBSR Environmental Monitoring Program is designed to verify that the radiation doses to the public are less than 10CFR20.1301 requirements and are ALARA. The methods used involve active and routine effluent sampling and monitoring, performing environmental surveys, and monitoring of sewer releases. These methods are described in FSAR paragraph 11.1.4.3. Real-time monitoring instruments displayed in the reactor control room are capable of recognizing a potential elevated release from the NBSR. Reviews of the recorded release data are performed quarterly. Public dose is based on measured emissions and is determined by computational models. Passive radiation monitoring at the NIST site boundary using gamma ray detectors and TLDs or similar monitoring devices is also performed. Environmental surveys include sampling of grass and soil, and water sampling of local streams and ponds. The collected samples are analyzed for possible activation radionuclides and "ssion products. Water samples are also assayed for tritium.

Environmental samples of water, soil, and grass are collected and analyzed at least quarterly from a minimum of four locations for each sample type. Soil samples are collected during the non-growing season (October through March), and grass samples are collected during the normal growing season (April through September). This analysis typically has a sensitivity of better than 1 pCi for common "ssion products per sample. Liquid scintillation analysis of water samples is also done and typically has sensitivity better than 10 pCi/ml for tritium.

Radiation exposures from research activities are typically far below those of other operations at the NCNR. In 2023, 94% of the individuals at the NCNR received doses of less than 50 mrem. The majority of the doses received at the NCNR were from the ROE group. Although 2023 was an atypical year as the reactor was not operating, historical dose reviews demonstrate that typically 90% or more of the personnel at the NCNR receive less than 50 mrem, with the majority of the doses over 50 mrem received by ROE personnel conducting reactor operations and maintenance.