ML17265A047
| ML17265A047 | |
| Person / Time | |
|---|---|
| Site: | Northwest Medical Isotopes |
| Issue date: | 09/19/2017 |
| From: | Haass C Northwest Medical Isotopes |
| To: | Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML17265A039 | List: |
| References | |
| TAC MF6138 NWMl-2017-RAl-003, Rev. 0 | |
| Download: ML17265A047 (14) | |
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- NGfiTirNEst MEDICAL ISOTOPES ATTACHMENT 1 Response to U.S. Nuclear Regulatory Commission Northwest Medical Isotopes, LLC - Request for Additional Information Regarding Preliminary Safety Analysis Report Construction Permit Application Northwest Medical Isotopes, LLC Construction Permit Application Docket No. 50-609 (Document No. NWMl-2017-RAl-003, September 2017)
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00 e e NORTHWEST MEDICAL ISOTOPES Response to the U.S. Nuclear Regulatory Commission Northwest Medical Isotopes, LLC -
Request for Additional Information Regarding Preliminary Safety Analysis Report Construction Permit Application (TAC No. MF6138)
Docket No. 50-609 NWMl-2017-RAl-003, Rev. 0 September 2017 Prepared by:
Northwest Medical Isotopes, LLC 815 NW 9th Ave, Suite 256 Corvallis, OR 97330 I
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1 NWMl-2017-RAl-003, Rev. 0
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- filDBDlltJmFl.rntr.AllSOTOPCi Response to the U.S. Nuclear Regulatory Commission Northwest Medical Isotopes, LLC -
Request for Additional Information Regarding Preliminary Safety Analysis Report Construction Permit Application (TAC No. MF6138)
Docket No. 50-609 NWMl-2017-RAl-003, Rev. 0 Date Published:
September 19, 2017 Document Number. NWMl-2017-RAl-003 IRevision Number. O
Title:
Response to the U.S. Nuclear Regulatory Commission, Northwest Medical Isotopes, LLC - Request for Additional Information Regarding Preliminary Safety Analysis Report, Construction Permit Application (TAC No. MF6138), Docket No. 50-609 Approved by: Carolyn Haass Signature:
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NWMl-2017-RAl-003, Rev. 0 REVISION IDSTORY Rev Date Reason for Revision Revised By 0 9/19/2017" . Jssued for submittal to the NRC .. :*. *NIA
NWMl-2017-RAl-003, Rev. 0 TERMS Acronyms and Abbreviations ANS American Nuclear Society ANSI American National Standards Institute CAAS criticality accident alarm system CFR Code ofFedetal Regulations CSE criticality safety .evaluation .
ISG Interim Staff Guidance MCNP Monte Carlo N-Particle NCS nuclear criticality safety NRC U.S. Nuclear Regulatory Commission NWMI Northwest Medical Isotopes, LLC PSAR preliminary safety analysis report RAI request for additional information RPF radioisotope production facility SNM special nuclear material U.S. United States USL upper subcritical limit
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NWMl-2017-RAl-003, Rev. 0 CHAPTER 6.0 - ENGINEERED SAFETY FEATURES Section 6.2 - Detailed Descriptions RAI 6.3-18 The ISG au!(menting NUREG-1537, Part 2, Section 6.b.3, "Nuclear Criticality Safety for the Processing Facility," states that the applicant should provide a description of a criticality accident alarm system (CAAS) that is appropriate for thefacilityfor the type of radiation detected, the intervening shielding, and the magnitude of the minimum accident ofconcern. The technical basis shall demonstrate that the CAAS will meet the requirements of 10 CFR 70.24(a).
NWMI PSAR, Section 6.3, "Nuclear Criticality Safety in the Radioisotope Production Facility, "
states that evaluation of CAAS coverage will be peiformed after the.final design is complete but prior to startup. The presence ofpermanently-installed shielding could inteifere with the ability of detectors to detect the minimum accident ofconcern and there is a potential concern that the.final design may not be able to satisfy the detector coverage requirements of10 CFR 70.24.
Provide a description ofthe methods and COY/firm what will be used to evaluate coverage and when the CAAS evaluation will be performed Include appropriate construction-related commitments to ensure CAAS coverage in the facility where shielding is present.
Northwest Medical Isotopes, LLC (NWMI) will have a facility criticality accident alarm system (CAAS) that meets the requirements in Title 10, Code ofFederal Regulations, Part 70.24 (10 CFR 70.24),
"Criticality Accident Requirements," and commits to the current endorsed version of ANSI/ANS-8.3, Critically Accident Alarm System, with modifications as noted in U.S. Nuclear Regulatory Commission (NRC) Regulatory Guide 3.71 , Nuclear Criticality Safety Standards for Fuels and Materials Facilities.
The CAAS evaluation will be completed during the Radioisotope Production Facility (RPF) final design development and will be provided in the Operating License Application. CAAS coverage will be in all areas in which greater than the 10 CFR 70.24 mass limits of special nuclear material (SNM) are handled, used, or stored, and in all shielding areas of the RPF. In addition, controls will be established to preclude such SNM from areas where coverage is not provided. Each monitored area will be covered by two criticality detectors. The CAAS monitoring system will be capable of detecting a nuclear criticality that produces an absorbed dose in soft tissue of 20 Roentgen absorbed dose (rad) of combined neutron and gamma radiation at an unshielded distance of2 meters (m) from the material within 1 minute (min).
NWMI will establish a CAAS appropriate to the RPF for the type of radiation detected or shielding and magnitude of the minimum accident of concern. The CAAS description (in the final safety analysis r~port) will include the type of radiation detector and alarm; the detection threshold and minimum accident of concern; the detector logic used to provide dual alarm coverage, minimize false alarms, and detect failure; method used to determine radius of coverage; placement of alarms; and actions for maintaining and calibrating the system.
The CAAS design will consider potential damages from anticipated adverse events such as a fire, explosion, and corrosive atmosphere. The CAAS will be resistant to the RPF design-basis earthquake.
Operations will be rendered safe, by shutdown and quarantine, if necessary, in any area where CAAS coverage has been lost and not restored within a specified number of hours. The number of hours will be determined on a process-by-process basis, because shutting down certain processes, even to make them safe, may carry a larger risk than being without a CAAS for a short time. Compensatory measures (e.g.,
limiting access, halting SNM movement, or restoring CAAS coverage with an alternate instrument) when the CAAS is not functional will be determined for inclusion in the Operating License Application.
Emergency power will be provided to the CAAS by the uninterruptable power supply system.
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NWMl-2017-RAl-003, Rev . 0 Section 6.2 - Detailed Descriptions Re uest for additional information RAI 6.3-19 The ISGaugmenting NUREG-1537, Part 2, Section 6.b.3, "Nuclear Criticality Safety for the Processing Facility," states in the acceptance criteria that "NCS limits on controlled parameters will be established to ensure that all nuclear processes are subcritical, including an adequate margin ofsub-criticality for safety. "
NWMI PSAR, Section 6.3, "Nuclear Criticality Safety in the Radioisotope Production Facility,"
does not contain commitments to the technical practices identified in Section 6b.3, ofthe ISG.
Specifically, the application does not contain commitments related to the use ofeach controlled parameter.
Identify commitments to specific technical practices to ensure that all nuclear processes are subcritical.
Prior to end of construction and with the submittal of the Operating License Application, NWMI will ensure that all processes containing SNM within the RPF are evaluated to be subcritical under all normal and credible abnormal conditions. The evaluation will be done consistent with the upper subcritical limit (USL) as established in NWMI-2014-RPT-006, MCNP 6.1 Validations with Continuous Energy ENDFIB-Vlll Cross-Sections (Rev. 2).
Parameters available for nuclear criticality safety (NCS) controls include mass, geometry, density, enrichment, reflection, moderation, concentration, interaction, absorption, volume, heterogeneity, physicochemical form, and process variables. Of these parameters, NWMI will use controls for mass, geometry, moderation, volume, and interaction.
NWMI commits to evaluate controlled parameters at the associated safety limits (or more conservatively) and to evaluate parameters that are not controlled at the most reactive credible values. In addition, NWMI acknowledges that the use of a single NCS control to maintain the values of two or more controlled parameters constitutes only one component necessary to meet the double-contingency principle.
The order of preference for NCS controls used at the RPF will be the following:
- Passive engineered
- Active engineered
- Enhanced administrative
- Simple administrative controls NWMI will make every effort to use passive engineered controls, in particular, passive engineered geometry control. In addition, NWMI will strive to use NCS controls over reliance on the natural and credible course of events and will use control of two or more parameters over multiple controls on a single parameter, where possible. If the RPF operations rely on two or more controls on a single parameter, NWMI commits to using diverse over-redundant means of control.
NWMI will use the following general criteria in establishing controls on parameters:
When a single-parameter limit is used, all other parameters will be evaluated at the optimum or most reactive credible values. In determining single-parameter limits, specifying a particular physicochemical form and isotopic composition is permissible
- When process variables can affect the normal or most reactive credible values of parameters, controls to maintain the parameters within specified ranges will be established.
- When measurement of a parameter is needed, instrumentation subject to facility management measures will be used.
- When criticality control is based on measuring a single parameter, independent means of measurement will be used.
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NWMl-2017-RAl-003, Rev. 0 Section 6.2 - Detailed Descriptions Re uest for additional information
- Safety limits on controlled parameters will be established, taking any tolerances and uncertainty into account.
In addition, NWMI commits to specific criteria on the parameters (i.e., mass, geometry, moderation, volume, interaction) under NCS control at the RPF. The acceptance criteria for each area as a controlled parameter are summarized below.
Use of Mass When mass limits are derived for a material that is modeled assuming a given weight percent of SNM, compliance with the mass limit will be verified by either weighing the material and ascribing the entire mass to SNM or conducting physical measurements to establish the actual weight percent of SNM in the material.
- When the dimensions of equipment or containers with a fixed geometry are used to limit the mass of SNM, a conservative process density will be used to calculate the resulting mass.
- When overbatching of SNM is credible, the largest mass resulting from a single failure will be shown to be subcritical. Overbatching beyond double-batching should be considered unless the process requires multiple independent failures, or is precluded by equipment capacity, availability of material, or other considerations.
Use of Geometry
- Before operations are initiated, in response to changes to operations, and at periodic intervals, all dimensions relied on in demonstrating subcriticality will be verified. Relevant dimensions and material properties will be maintained in the facility's configuration management program.
Means of losing geometry control (e.g., corrosion, leakage, bulging, transfer to unfavorable geometry, changes to a more reactive physicochemical form) will be evaluated and controls established as needed if they are credible.
- Neutron interaction with other SNM-bearing equipment will be considered as part of the demonstration of subcriticality, unless individual units meet the criteria for being considered isolated from a neutronic perspective, including the introduction of any portable SNM-bearing containers.
Use of Moderation
- ANSVANS-8.22, Nuclear Criticality Safety Based on Limiting and Controlling Moderators ,
must be met.
- Physical structures will be designed, first preference, to preclude the ingress of moderators .
- Moderation-controlled areas may be used to exclude moderators from whole areas. Engineered means (e.g., double roof, double-sleeved pipes, exclusion of sprinklers, raised/sloped floors) are the primary means of excluding moderators from such areas.
- After evaluation of all credible sources of moderator intrusion into such areas, the areas are conspicuously marked and administrative controls are established to prevent the introduction of moderators.
Firefighting procedures for use in moderation-controlled areas will be evaluated, including restrictions on the use of moderating firefighting agents, and will be included in procedures and training.
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NWMl-2017-RAl-003, Rev. 0 Section 6.2 - Detailed Descriptions Re uest for additional information Use of Volume
- Fixed geometry will be used to restrict the volume of SNM. The preferred method is limiting equipment and containers to less than a subcritical volume. Limiting material to part of a larger geometry (e.g., by active level probes or use of overflow holes) may also be used.
- Maximum subcritical volume will be evaluated assuming the most reactive credible geometry, optimum moderation, and full water reflection. Spherical geometry will typically be the most reactive (though this could depend on the specific boundary conditions to be applied).
RAI 6.3-20 Section 6b.3 of the ISG Augmenting NUREG-153 7, Part 2, states that the applicant should include a summary description ofa documented, reviewed, and approved validation report (by NCS fanction and management) for each methodology that will be used to perform an NCS analysis. The summary description of a reference manual or validation report should include the following: a summary of the theory of the methodology that is sufficiently detailed and clear to be understood, including the method used to select the benchmark experiments, determine the bias and uncertainty in the bias, and determine the upper subcritical limit (USL).
The Validation Report (NWMI-2014-RPT-006, "MCNP 6.1 Validations with Continuous Energy ENDFIB-Vlll Cross-Sections," Rev. 2) includes a revised calculated VSL of0.9240.
Additional information is needed to understand how NWMI expects to ensure that all processes containing special nuclear material under normal and credible abnormal conditions will meet the revised VSL of0.9240.
Provide additional information to clarify how NWMI will update criticality calculations and design analysis to incorporate the revised VSL of0.9240.
NWMI will ensure that all processes containing SNM under normal and credible abnormal conditions will meet the revised USL of0.9240 provided in NWMI-2014-RPT-006.
NWMI will use the Monte Carlo computer code, MCNP, to calculate the effective multiplication factor keff, and update all calculations performed during the preliminary design phase. Criticality safety evaluations (CSE) will be updated and NCS operating limits will be established based on analyses assuming optimum or the most reactive credible values of parameters (e.g., the most reactive conditions physically possible or bounding values limited by regulatory requirements), unless specified controls are implemented to limit parameters to a range of values. If less than the optimum values are used, and corresponding controls are not identified, the basis will be justified in the CSE. NCS operating limits may be established as appropriate to ensure that safety limits are unlikely to be exceeded. If separate NCS operating limits are specified, process variability and uncertainty should be considered and additional conservatism may be applied.
The specific controls and management measures necessary to enforce NCS safety limits and/or operating limits will be specified in the CSE. Each CSE will be incorporated into the final RPF integrated safety analysis and configuration management program.
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REFERENCES 10 CFR 70, "Domestic Licensing of Special Nuclear Material," Code ofFederal Regulations, Office of the Federal Register, as amended.
ANSI/ANS-8.3, Critically Accident Alarm System, American Nuclear Society, La Grange Park, Illinois, 1997 (R.2003, R2012).
ANSI/ANS-8.22, Nuclear Criticality Safety Based on Limiting and Controlling Moderators , American Nuclear Society, La Grange Park, Illinois, I 997 (R2006, R20 I I, R20 I 6).
NRC, 2012, Final Interim Staff Guidance Augmenting NUREG-1537, "Guidelines for Preparing and Reviewing Applications for the Licensing ofNon-Power Reactors," Parts 1 and 2, for Licensing Radioisotope Production Facilities and Aqueous Homogeneous Reactors, Docket Number:
NRC-2011-0135, U.S. Nuclear Regulatory Commission, Washington, D.C., October 17, 2012.
NUREG-1537, Guidelines for Preparing and Reviewing Applications for the Licensing ofNon-Power Reactors: Standard Review Plan and Acceptance Criteria, Part 2, U.S. Nuclear Regulatory Commission, Office ofNuclear Reactor Regulation, Washington, D.C., February 1996.
NWMI-2013-021 , Construction Permit Application for Radioisotope Production Facility, Rev. 3, Northwest Medical Isotopes, LLC, Corvallis, Oregon, 2017.
NWMI-2014-RPT-006, MCNP 6.1 Validations with Continuous Energy ENDF/B-VII.1 Cross-Sections, Rev. 2, Northwest Medical Isotopes, LLC, Corvallis, Oregon, 2017.
Regulatory Guide 3.71 , Nuclear Criticality Safety Standards for Fuels and Materials Facilities, Rev. 2, U.S. Nuclear Regulatory Commission, Washington, D.C., December 2010.
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