ML25189A444
| ML25189A444 | |
| Person / Time | |
|---|---|
| Site: | National Bureau of Standards Reactor |
| Issue date: | 08/19/2025 |
| From: | Hudson J NRC/NRR/DANU/UNPL |
| To: | Adams J US Dept of Commerce, National Institute of Standards & Technology (NIST) |
| Hudson J | |
| References | |
| EPID L-2025-LLA-0007 | |
| Download: ML25189A444 (1) | |
Text
Dr. James Adams, Director National Institute of Standards and Technology NIST Center for Neutron Research U.S. Department of Commerce 100 Bureau Drive, Mail Stop 8461 Gaithersburg, MD 20899-8461
SUBJECT:
NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY - ISSUANCE OF AMENDMENT NO. 16 TO RENEWED FACILITY OPERATING LICENSE NO.
TR-5 FOR THE NATIONAL BUREAU OF STANDARDS TEST REACTOR RE:
INNER AND OUTER FLOW SCRAM BYPASS REMOVAL (EPID NO. L-2025-LLA-0007)
Dear Dr. Adams:
The U.S. Nuclear Regulatory Commission (the Commission) has issued the enclosed Amendment No. 16 to Renewed Facility Operating License No. TR-5 for the National Institute of Standards and Technology National Bureau of Standards Test Reactor. The amendment revises technical specification (TS) 3.2.2, Reactor Safety System Channels, table 3.2.2, Reactor Safety System Channels Minimum Nuclear and Process Channels Required, and TS 4.2.2, Reactor Safety Channels, table 4.2.2, Surveillance Requirements for the Scram and Confinement Channels, in response to the application dated December 19, 2024 (Agencywide Documents Access and Management System Package Accession No. ML25014A396), as supplemented by letter dated April 22, 2025 (ML25112A275). The revisions eliminate the ability to bypass either the inner or outer plenum flow scram channels during forced flow operation and require surveillances for both the inner and outer flow scram channels.
August 19, 2025
J. Adams A copy of the related safety evaluation is also enclosed. The Notice of Issuance will be included in the Commissions monthly Federal Register notice. If you have any questions, please contact me at (301) 287-0583, or via email at Justin.Hudson@nrc.gov.
Sincerely, Justin C. Hudson, Project Manager Non-Power Production and Utilization Facility Licensing Branch Division of Advanced Reactors and Non-Power Production and Utilization Facilities Office of Nuclear Reactor Regulation Docket No. 50-184 License No. TR-5
Enclosures:
- 1. Amendment No. 16 to Renewed Facility Operating License No. TR-5
- 2. Safety Evaluation cc w/enclosures: GovDelivery Subscribers Signed by Hudson, Justin on 08/19/25
ML25189A444 NRR-058 OFFICE NRR/DANU/UNPL/PM NRR/DANU/UNPL/LA OGC/NLO NAME JHudson NParker JWachutka DATE 7/9/025 7/10/2025 8/11/2025 OFFICE NRR/DSS/SFNB/BC NRR/DANU/UNPL/BC NRR/DANU/UNPL/PM NAME SKrepel JRady JHudson DATE 6/18/2025 8/19/025 8/19/2025 NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY DOCKET NO. 50-184 NATIONAL BUREAU OF STANDARDS TEST REACTOR AMENDMENT TO RENEWED FACILITY OPERATING LICENSE Amendment No. 16 License No. TR-5 1.
The U.S. Nuclear Regulatory Commission (the Commission) has found that:
A.
The application for amendment to Renewed Facility Operating License No. TR-5, filed by the National Institute of Standards and Technology (the licensee) on December 19, 2024, as supplemented by letter dated April 22, 2025, complies with the standards and requirements of the Atomic Energy Act of 1954, as amended (the Act), and the Commissions rules and regulations set forth in Title 10 of the Code of Federal Regulations (10 CFR) Chapter I; B.
The facility will operate in conformity with the application, the provisions of the Act, and the rules and regulations of the Commission; C.
There is reasonable assurance that (i) the activities authorized by this amendment can be conducted without endangering the health and safety of the public and (ii) such activities will be conducted in compliance with the Commissions regulations; D.
The issuance of this amendment will not be inimical to the common defense and security or to the health and safety of the public; and E.
The issuance of this amendment is in accordance with 10 CFR Part 51, Environmental Protection Regulations for Domestic Licensing and Related Regulatory Functions, of the Commissions regulations and all applicable requirements have been satisfied.
2.
Accordingly, the license is amended as described in Attachment 1 to this license amendment and by changes to the Technical Specifications as described in Attachment 2.
Paragraph 2.C.2 of Renewed Facility Operating License No. TR-5 is hereby amended to read as follows:
2.
The technical specifications contained in Appendix A, as revised by Amendment No. 16, are hereby incorporated in the license. The licensee shall operate the reactor in accordance with the technical specifications.
3.
This license amendment is effective as of its date of issuance and shall be implemented within 30 days.
FOR THE NUCLEAR REGULATORY COMMISSION Jeffrey S. Rady, Chief Non-Power Production and Utilization Facility Licensing Branch Division of Advanced Reactors and Non-Power Production and Utilization Facilities Office of Nuclear Reactor Regulation Attachments:
1.
Changes to Renewed Facility Operating License No. TR-5 2.
Changes to Appendix A, Technical Specifications Date of Issuance: August 19, 2025 JEFFREY RADY Digitally signed by JEFFREY RADY Date: 2025.08.19 15:20:46 -04'00' ATTACHMENT 1 TO LICENSE AMENDMENT NO. 16 RENEWED FACILITY OPERATING LICENSE NO. TR-5 DOCKET NO. 50-184 Replace the following page of Renewed Facility Operating License No. TR-5 with the attached revised page. The revised page is identified by amendment number and contains a marginal line indicating the area of change.
Renewed Facility Operating License No. TR-5 Remove Insert Amendment No. 16 August 19, 2025 a.
up to 45.0 kilograms of contained uranium-235 of any enrichment, provided that less than 5.0 kilograms of this amount be unirradiated; b.
to possess and use, but not to separate such special nuclear material as may be produced by operation of the reactor.
3.
Pursuant to the Act and 10 CFR Part 30, Rules of General Applicability to Domestic Licensing of Byproduct Material, to receive, possess, and use in connection with the operation of the reactor: (1) a two-curie americium-beryllium neutron source which may be used for reactor startup, and (2) up to a total of 8 curies of byproduct material (Atomic number 1 through 83) and up to 100 micro curies of americium-241, in the form of instrument calibration sources.
4.
Pursuant to the Act and 10 CFR Part 30 to possess, use, and transfer but not to separate, except for byproduct material produced in non-fueled experiments, such byproduct material as may be produced by operation of the reactor.
C.
This license shall be deemed to contain and is subject to the conditions specified in Parts 20, 30, 50, 51, 55, 70, 73, and 100 of the Commissions regulations; is subject to all applicable provisions of the Act and rules, regulations, and orders of the Commission now or hereafter in effect; and is subject to the additional conditions specified below:
1.
The licensee is authorized to operate the reactor at steady-state power levels up to a maximum of 20 megawatts (thermal).
2.
The technical specifications contained in Appendix A, as revised by Amendment No. 16, are hereby incorporated in the license. The licensee shall operate the reactor in accordance with the technical specifications.
3.
The licensee shall maintain and fully implement all of the provisions of the Commission-approved physical security plan, including changes made pursuant to the authority of 10 CFR 50.54(p). The approved physical security plan consists of a National Institute of Standards and Technology document, withheld from public disclosure pursuant to 10 CFR 73.21, entitled, National Institute of Standards and Technology Center for Neutron Research Physical Security Plan, dated June 12, 2020, transmitted by letter dated June 12, 2020.
ATTACHMENT 2 TO LICENSE AMENDMENT NO. 16 RENEWED FACILITY OPERATING LICENSE NO. TR-5 DOCKET NO. 50-184 Replace the following pages of Appendix A, Technical Specifications, with the attached revised pages. The revised pages are identified by amendment number and contain marginal lines indicating the areas of change.
Technical Specifications Remove Insert 16 16 34 34
Amendment No. 16 August 19, 2025 16 beginning-of-life shim arm worths with the shim arms operating at the design speed of their constant speed mechanisms. The analysis shows that the most severe accident, a startup from source level, will not result in core damage.
3.2.2 Reactor Safety System Channels Applicability: Required instrument channels Objective: To provide protective action for nuclear and process variables to ensure the LSSS values are not exceeded.
Specifications The reactor shall not be operated unless the channels described in Table 3.2.2 are operable and the information is displayed in the reactor Control Room.
Table 3.2.2 Reactor Safety System Channels Minimum Nuclear and Process Channels Required Channel Scram Major Scram Rundown (1) High Flux level 2
(2) Short period below 5% rated power 2
(3) Low reactor vessel D2O level 1,2 2
(4) Low flow reactor outlet 2 1
(5) Low flow reactor inner plenum 2 1
(6) Low flow reactor outer plenum 2 1
(7) Manual (outside of the Control Room) 1 (8) Manual 1
1 (9) Reactor Outlet Temperature2 1
(10) Gaseous Effluent Monitors3 2
1 One (1) of two (2) channels may be bypassed for tests or during the time maintenance involving the replacement of components and modules or calibrations and repairs are actually being performed.
2 May be bypassed during periods of reactor operation when a reduction in Limiting Safety System Settings are permitted by the specifications of Sections 2.2(4) and 3.3.1(1).
3 See specifications of Section 3.7.1
Amendment No. 16 August 19, 2025 34 Basis The shim arm drives are constant speed mechanical devices. A reactor scram is aided by a spring that opposes drive motion during shim arm withdrawal.
Withdrawal and insertion speeds or scram time should not vary except as a result of mechanical wear. The surveillance frequency is chosen to provide a significant margin over the expected failure or wear rates of these devices.
4.2.2 Reactor Safety System Channels Applicability: Required instrument channels Objective: To ensure reliability of protective action for nuclear and process variables.
Specifications The Scram and Confinement Channels shall have the surveillance requirements shown in Table 4.2.2.
Table 4.2.2 Surveillance Requirements for the Scram and Confinement Channels Channel Action Required Surveillance Required (1) High Flux level Scram X, A (2) Short period below 5% rated power Scram X, A (3) Low reactor vessel D2O level Scram X, A (4) Low flow reactor outlet Scram X, A (5) Low flow reactor inner plenum Scram X, A (6) Low flow reactor outer plenum Scram X, A (7) Manual (outside of the Control Room)
Scram X, A (8) Manual Scram X, A (9) Normal Air Exhaust Activity High Major Scram X, A (10) Irradiated Air Activity High Major Scram X, A (11) Stack Air Activity High Major Scram X, A (12) Reactor Coolant Outlet Temperature Rundown X, A X - Channel test before startup after a shutdown of longer than 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, or quarterly.
A - Annual Channel Calibration.
Basis To ensure that instrument failures do not go undetected, frequent surveillance of the listed channels is required and operating experience has shown these frequencies to be adequate to ensure channel operability.
SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO. 16 TO RENEWED FACILITY OPERATING LICENSE NO. TR-5 NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY NATIONAL BUREAU OF STANDARDS TEST REACTOR DOCKET NO. 50-184
1.0 INTRODUCTION
By letter dated December 19, 2024 (Agencywide Documents Access and Management System Package Accession No. ML25014A397), as supplemented by letter dated April 22, 2025 (ML25112A275), the National Institute of Standards and Technology (NIST) Center for Neutron Research (NCNR) requested an amendment to Renewed Facility Operating License No. TR-5 for the National Bureau of Standards Test Reactor (NBSR) under the provisions of Title 10 of the Code of Federal Regulations (10 CFR) Section 50.90, Application for amendment of license, construction permit, or early site permit. Specifically, the NCNR requested to revise the facilitys technical specifications (TSs) to eliminate the ability to bypass either the inner or outer plenum flow scram channels during forced flow reactor operation and to require surveillances for both the inner and outer flow scram channels.
The supplemental letter dated April 22, 2025, provided additional information that clarified the application, did not expand the scope of the application as originally noticed, and did not change the NRC staffs original proposed no significant hazards consideration determination as published in the Federal Register on March 18, 2025 (90 FR 12568).
2.0 REGULATORY EVALUATION
The U.S. Nuclear Regulatory Commission (NRC, the Commission) staff considered the following applicable regulatory requirements and guidance during its review of the proposed changes:
Section 50.92, Issuance of amendment, of 10 CFR, which states, in part, that in determining whether an amendment to a license will be issued, the Commission will be guided by the considerations which govern the issuance of initial licenses to the extent applicable and appropriate.
NUREG-1537, Part 1, Guidelines for Preparing and Reviewing Applications for the Licensing of Non-Power Reactors: Format and Content (ML042430055), which provides guidance to applicants and licensees on preparing non-power reactor license applications and TSs.
NUREG-1537, Part 2, Guidelines for Preparing and Reviewing Applications for the Licensing of Non-Power Reactors: Standard Review Plan and Acceptance Criteria (ML042430048), which provides guidance on the conduct of NRC licensing reviews of non-power reactor licensing applications.
American National Standards Institute/American Nuclear Society (ANSI/ANS)-15.1-2007, The Development of Technical Specifications for Research Reactors, which provides guidance that identifies and establishes the content of TSs for research and test reactors.
3.0 TECHNICAL EVALUATION
3.1 Background
The NBSR is a heavy water moderated and cooled reactor that operates near atmospheric pressure. In its submittal, the NCNR describes the primary coolant flow path. The primary coolant system consists of three operating main primary cooling pumps with one installed spare main pump, two plate-type heat exchangers rated for 10 megawatts each, and various isolation valves in the system. Flow starts from the main primary pumps, flows through the heat exchangers, through a strainer and then splits in between two plenums, the inner and outer plenums. The distribution of the coolant flow between the two plenums is governed by the inherent flow resistance of the two different paths. The inner plenum is located within and concentric to the outer plenum, and it serves the inner six most fuel elements and the central thimble in the reactor core with a total flow of 2,300 gallons per minute (gpm). The outer plenum services the remaining 24 fuel elements and thimbles with about 6,400 gpm. The total flow through the core is 8,700 gpm. The coolant within each plenum travels up through the respective plenum elements, exits into the reactor vessel, and then the coolant travels down through the two outlet pipes of the reactor vessel before returning to the main primary coolant pumps. This flow path is shown in the NBSR safety analysis report (SAR), chapter 5, Reactor Coolant Systems (ML041120216), page 5-49, and is reproduced below as figure 1.
Figure 1: Simplified Primary Coolant Flow Path The NBSR reactor safety system includes three low flow reactor scram channels. The three low flow scram channels are: the inner plenum flow channel, the outer plenum flow channel, and the outlet flow channel.
In May of 1984, the license renewal and power increase amendment, Amendment No. 5 (ML20090K707), for the NBSR made changes to the TSs that added the ability to bypass one of the two plenum low flow scram channels during reactor operations. Prior to Amendment No. 5, the flow channels could not be bypassed during reactor operations. As discussed in its current submittal, the NCNR recently identified that the changes made to the TSs via Amendment No. 5 for operability requirements of the plenum flow channels do not appear to be fully justified. All current safety analysis scenarios and technical bases assume that both the inner and outer plenum flow channels are operable to ensure adequate cooling and to avoid overheating. Thus, there is no technical basis or corresponding safety analysis that would allow operation of the reactor if any of the plenum flow channels are bypassed. Additionally, current TSs table 3.2.2, Reactor Safety System Channels Minimum Nuclear and Process Channels Required, and table 4.2.2, Surveillance Requirements for the Scram and Confinement Channels, as of Amendment No. 15 (ML23055A300), dated March 2, 2023, permit reactor operation with either one of the inner or outer plenum flow channels bypassed. Therefore, the existing TSs are not in accordance with the available technical basis and safety analyses.
As described in its submittal, the NCNR performed a review of shift supervisor logs and noted that (1) there are no records of the reactor being operated when one of the inner or outer plenum flow channels was bypassed, and (2) step 2.2.2 and table 11 of Operating Instruction 1.1.0, Reactor Startup Checklist, require operators to perform a channel test of the inner and outer plenum flow channels. Accordingly, while the TSs do not provide clear restrictions on the operation of the reactor with either of the plenum flow channels bypassed, operation of the reactor in this configuration has not actually been practiced and is precluded by procedures.
The NCNR stated that the purpose of the proposed amendment is to align the TSs to be consistent with the available technical basis and safety analyses to ensure that the designed safety margins of the reactor are maintained.
3.2 Evaluation of Technical Justification for Proposed TSs Changes The NRC staff notes that the existing safety analyses of the NBSR are consistent with each other and the pre-1984 (i.e., Amendment No. 5) TSs in that both the inner and outer plenum flow channels are required to be in service during forced flow operation. As such, modifying the existing TSs to preclude bypassing either of the plenum flow channels during forced flow operation would bring the TSs into alignment with the existing technical basis and analysis of record and restore their consistency.
In its submittal, the NCNR performed two safety analyses using RELAP5 to explore the potential impacts of either plenum flow channels being bypassed. The two safety analyses were described as: accident, which is when the inner plenum flow scram channel is bypassed; and reference, which is when the inner plenum flow scram channel functions as intended. The analyses examine the scenarios of an inadvertent closure of either primary inlet valves when the corresponding plenum flow channel is not operational. The NCNR indicated in its submittal that, based on these analyses, when one of the plenum flow channels is bypassed and the corresponding primary coolant flow is lost (due to the inadvertent valve closure or similar event resulting in loss of primary coolant flow), the reactor scram initiation was found to happen after boiling occurs in one or more of the affected plenums fuel elements. The NRC staff notes that, based on the event evolution in the analysis, this is because as the primary inlet valve for the plenum with the bypassed flow channel closes, the bulk of the primary coolant flow is diverted through the remaining plenum. The operational flow channel for this plenum and the outlet flow channel both register minor changes in flow but experience flow rates that are still in excess of the scram setpoints, thus preventing the reactor from immediately scramming even though the affected plenum is starved of coolant.
In its supplemental letter dated April 22, 2025, the NCNR provided a figure showing the difference between the temperature of the fuel plates during the two different analyses. The figure has been reproduced below as figure 2. In the accident condition, the NCNR stated that as the inner plenum isolation valve, DWV-2, begins to close, the temperature of the fuel plates begins to rise gradually in the first 20 seconds, reaching approximately 400 Kelvin (K). After the first 20 seconds, a rapid increase in temperature is observed, with the fuel plating reaching as high as 890 K before the simulation fails, which exceeds the safety limit. In the reference condition, the fuel plate temperature never exceeds 400 K when the reactor scrams 15.5 seconds after DWV-2 begins to close.
Figure 2: Inner Core Temperatures of Six Elements in the Center of the Core The NRC staff examined the NCNR submittal to assess the completeness of the analyses and the adequacy of the results. The NRC staff noted that the nodalization of the RELAP5 model reasonably represents the major systems of the NBSR, the analysis input accurately reflects the starting boundary conditions and performance characteristics of the NBSR, and the control system logic for the reactor scram is appropriately modeled.
The NRC staff also examined the correlations used in the RELAP5 thermal-hydraulic model of the reactor and concluded that, while they are older correlations, they are reasonably representative of the NBSR fuel arrangement and subchannel configuration. In particular, the NRC staff noted that the Mirshak correlation is used to determine the burnout condition of the fuel elements (the point of maximum heat flux where film boiling of the coolant occurs and cladding surface temperature exceeds the melting point). The empirically-derived Mirshak correlation was developed in 1959 using electrically heated surfaces that are water-cooled by forced convection. Both annular and rectangular coolant passages were utilized, and experimental results showed surface curvature and equivalent diameter of the heated elements had negligible effect on the results. The range of conditions over which the correlation was derived (e.g., coolant velocity, pressure, subcooling, etc.) encompass those at the NBSR.
3.3 Technical Conclusions Based on the above discussion, the NRC staff finds that the safety analyses performed are reasonable and that the results are acceptable. The NRC staff also finds that both the inner and outer plenum flow scram channels cannot be bypassed during forced flow operation. Therefore, based on this, the existing safety analyses of record, and the associated technical justification, the NRC staff finds the NCNRs proposed revision to the NBSR TSs to be acceptable.
3.4 Proposed Technical Specifications Changes For this section, proposed deletions will be represented as text in strikethrough and proposed additions will be represented as underlined text.
The proposed changes to TS 3.2.2, Reactor Safety System Channels, Table 3.2.2, Reactor Safety System Channels Minimum Nuclear and Process Channels Required, are:
Channel Scram Major Scram Rundown (1) High Flux level 2
(2) Short period below 5% rated power 2
(3) Low reactor vessel D2O level 1,23 2
(4) Low flow reactor outlet 23 1
(5) Low flow reactor inner or outer plenum 2, 3 1
(6) Low flow reactor outer plenum2 1
(67) Manual (outside of the Control Room) 1 (78) Manual 1
1 (89) Reactor Outlet Temperature23 1
(910) Gaseous Effluent Monitors34 2
1 One (1) of two (2) channels may be bypassed for tests or during the time maintenance involving the replacement of components and modules or calibrations and repairs are actually being performed.
2 One (1) of these two (2) flow channels may be bypassed for tests, or during the time maintenance involving the replacement of components and modules or calibrations and minor repairs are actually being performed. However, outlet flow may not be bypassed unless both inner and outer low flow reactor inlet safety systems are operating.
23 May be bypassed during periods of reactor operation when a reduction in Limiting Safety System Settings are permitted by the specifications of Sections 2.2(4) and 3.3.1(1).
34 See specifications of Section 3.7.1 The proposed change to item (3) in table 3.2.2 replaces the indication of footnote 3 with footnote 2. This proposed change is an editorial change, and therefore, the NRC staff finds this proposed change acceptable.
The proposed change to item (4) in table 3.2.2 replaces the indication of footnote 3 with footnote 2. This proposed change is an editorial change, and therefore, the NRC staff finds this proposed change acceptable.
The proposed changes to item (5) in table 3.2.2 are as follows: a deletion of the option of the outer plenum scram channel, and the deletion of footnote three. The NRC staff notes that the purpose of the deletion of the outer plenum scram option from item (5) is to separate the two scram channels (inner plenum and outer plenum) into two separate requirements. The NRC staff finds that the forced coolant flow scram channel requirements are consistent with the guidance in NUREG-1537, Part 1, Appendix 14.1, Format and Content of Technical Specifications for Non-Power Reactors, section 3.2, Reactor Control and Safety Systems item (4), Scram Channels. The NRC staff finds that this change is consistent with the analyses described in section 3.2 of this safety evaluation (SE), which indicate that both inlet flow scram channels are required for safe operation. Therefore, the NRC staff finds that this proposed change is acceptable.
The proposed change to add item (6) to table 3.2.2 adds the low outer plenum flow as a separate requirement from item (5). This proposed change eliminates the possibility of operating with one of the two inlet flow scram channels during forced flow reactor operations. With this proposed change, both the inner and outer plenum flow scram channels will be required for forced flow reactor operations. The NCNR stated in its submittal that these proposed changes will ensure that the TSs and existing safety analysis are in agreement. The NRC staff finds that the proposed change is consistent with the analyses described in section 3.2 of this SE and is consistent with the guidance in NUREG-1537, Part 1, Appendix 14.1, Section 3.2. Therefore, the NRC staff finds that this proposed change is acceptable.
The proposed changes for the remainder of the scram channels (i.e., Manual [outside of the Control Room], Manual, Reactor Outlet Temperature, Gaseous Effluent Monitors) renumber them to be (7)-(10). The proposed changes also renumber the Reactor Outlet Temperature scram channel footnote from 3 to 2 and the Gaseous Effluent Monitor footnote from 4 to 3. The NRC staff finds that these proposed changes are editorial, conforming changes and therefore acceptable.
The proposed change deletes footnote 2. This proposed deletion eliminates the ability to bypass the inner or outer plenum scram channels during operation. The NRC staff finds that the proposed change is supported by the analyses described in section 3.2 of this SE. Therefore, the NRC staff finds that this proposed change is acceptable.
The proposed changes to TS 4.2.2, Reactor Safety System Channels, Table 4.2.2, Surveillance Requirements for the Scram and Confinement Channels, are:
Table 4.2.2 Surveillance Requirements for the Scram and Confinement Channels Channel Action Required Surveillance Required (1) High Flux level Scram X, A (2) Short period below 5% rated power Scram X, A (3) Low reactor vessel D2O level Scram X, A (4) Low flow reactor outlet Scram X, A (5) Low flow reactor inner or outer plenum Scram X, A (6) Low flow reactor outer plenum Scram X, A (67) Manual (outside of the Control Room)
Scram X, A (78) Manual Scram X, A (89) Normal Air Exhaust Activity High Major Scram X, A (910) Irradiated Air Activity High Major Scram X, A (101) Stack Air Activity High Major Scram X, A (112) Reactor Coolant Outlet Temperature Rundown X, A X - Channel test before startup after a shutdown of longer than 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, or quarterly.
A - Annual Channel Calibration.
The proposed change to item (5) of TS table 4.2.2 deletes the outer plenum from the surveillance requirement. The NRC staff notes that this proposed change is part of the proposed change to item (6) of TS table 4.2.2 and separates the inner and outer flow scram channel surveillances and removes the ability to only do surveillances and a calibration on either the inner or outer flow scram channel. This proposed change requires a channel test before a reactor startup after a shutdown of longer than 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, or quarterly; and an annual calibration for both the inner and outer plenum flow scram channels. The NRC staff finds that this proposed change is consistent with the guidance in NUREG-1537, Part 1, Appendix 14.1, Section 4.2, Reactor Control and Safety Systems, item (5), Scram and Power Measuring Channels, which states that channel tests of all scram channels required by the TSs should be performed before each reactor startup after a shutdown longer than 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> and if the reactor operating schedule calls for no secured shutdowns, then channel tests should be performed at least quarterly. The NRC staff also finds that the proposed calibration schedule is consistent with ANSI/ANS-15.1-2007, section 4.2, Reactor control and safety systems, which states that scram channel calibrations should be on an annual frequency. Therefore, the NRC staff finds that the proposed changes are acceptable.
The remainder of the proposed changes to TS table 4.2.2 renumber the channels Manual (outside of the Control Room), Manual, Normal Air Exhaust Activity High, Irradiated Air Activity High, Stack Air Activity High, and Reactor Coolant Outlet Temperature to account for the proposed addition of the outer plenum channel surveillance. The NRC staff finds that these proposed changes are editorial, conforming changes and therefore acceptable.
4.0 STATE CONSULTATION
In accordance with the Commissions regulations, the Maryland State official was notified of the proposed issuance of the amendment on June 3, 2025. The State official did not provide any comments.
5.0 ENVIRONMENTAL CONSIDERATION
The amendment changes requirements with respect to the installation or use of facility components located within the restricted area as defined in 10 CFR Part 20, Standards for Protection against Radiation. The NRC staff has determined that the amendment involves no significant increase in the amounts and no significant changes in the types of any effluents that may be released offsite, and that there is no significant increase in individual or cumulative occupational radiation exposure. The Commission has previously issued a proposed finding that the amendment involves no significant hazards consideration, as published in the Federal Register (FR) on March 18, 2025 (90 FR 12568), and there were no public comments on such findings. Accordingly, the amendment meets the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9). Pursuant to 10 CFR 51.22(b), no environmental impact statement or environmental assessment need be prepared in connection with the issuance of the amendment.
6.0 CONCLUSION
The Commission has concluded, based on the considerations discussed above, that: (1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, (2) there is reasonable assurance that such activities will be conducted in compliance with the Commissions regulations, and (3) the issuance of the amendment will not be inimical to the common defense and security or to the health and safety of the public.
Principal Contributors: J. Hudson, NRR K. Heller, NRR Date: August 19, 2025