ML18341A240

North Carolina State University License Amendment Request for Fueled Experiments

ML18341A240
Person / Time
Site:	North Carolina State University
Issue date:	12/04/2018
From:	North Carolina State University
To:	Office of Nuclear Reactor Regulation
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ML18341A237	List: ML18341A238 ML18341A240 ML18341A241 ML18341A242
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Download: ML18341A240 (9)

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LICENSE AMENDMENT REQUEST FOR FUELED EXPERIMENTS Nuclear Reactor Program NORTH CAROLINA STATE UNIVERSITY RALEIGH, NORTH CAROLINA 27695 LICENSE NO. R120 DOCKET NO. 50297 4DECEMBER2018

TABLE OF CONTENTS EXECUTIVE

SUMMARY

.................................................................................................................................. 3 DISCUSSION OF R120 LICENSE CHANGE ...................................................................................................... 6 DISCUSSION OF TECHNICAL SPECIFICATION CHANGES ................................................................................ 6 TS 1.2.9.e - Fueled Experiment ................................................................................................................ 6 TS 3.5 - Radiation Monitoring Equipment ................................................................................................ 7 TS 3.8 - Operations with Fueled Experiments .......................................................................................... 8 TS 4.4 - Radiation Monitoring Equipment ................................................................................................ 9 Table 1 (Ref. Table 151): Radiation Doses for Fueled Experiments for planned vented and accidental releases, as compared to 10 CFR Part 20 Limits ........................................................................................... 4 2

EXECUTIVE

SUMMARY

An amendment to the R120 Reactor License and Technical Specifications (TS) is requested based on planned experimental needs. The requested changes are as follows:

1) R120 reactor license Section 2.B.(2) regarding possession limits for fissionable materials to be used in fueled experiments

2) Technical Specification 1.2.9.e for the definition of a fueled experiment

3) Technical Specification 3.5 for monitoring of vented fueled experiments

4) Technical Specification 3.8 for limiting conditions for operations for fueled experiments

5) Technical Specification 4.4 for surveillance of vented fueled experiments To meet planned experiment needs, a change to Section 2.B.(2) of the R120 reactor license is requested to allow for possession of materials to be used in fueled experiments. Possession of Uranium235, Neptunium237, and Plutonium239 for fueled experiments is requested.

TS 1.2.9.e defines fueled experiments, and is revised to specify the type and quantity of fissionable material that is considered a fueled experiment. Threshold limits on fission rate and total number of fissions are established for experiments containing uranium which are based on limiting the radiation dose from a potential release to one percent (1%) of the annual public dose limit given in 10 CFR Part 20, i.e. a Total Effective DoseEquivalent of 0.001 rem. These threshold limits are from a continuous release of fission gases and halogens with the reactor building in normal ventilation for 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. Experiments involving the neutron irradiation of uranium below these threshold limits are not classified as fueled experiments. Experiments involving the neutron irradiation of uranium in excess of these threshold limits, the neutron irradiation of any amount of another fissionable material, or a planned vented release of fission gases or halogens are defined as fueled experiments.

TS 3.5 is revised to include monitoring of the vented fueled experiment exhaust for radioactivity and flow rate. Alarm set points in the revised TS 3.5 are based on meeting TS 3.8 and limiting potential public dose to 0.003 rem.

TS 3.8 provides limiting conditions for operation for fueled experiments and is revised to establish upper limits for the allowable fission rate and total number of fissions. These upper limits are based on limiting potential radiation dose from a release to three percent (3%) of the annual radiation dose limits given in 10 CFR Part 20 (see Table 1 below). TS 3.8 requires controls to prevent accidental releases associated with a failure of the fueled experiment encapsulation. TS 3.8 requires monitoring of the vented fueled experiment exhaust gas for radioactivity and flow rate when a vented fueled experiment is being performed. Additional controls for vented fueled experiments to limit the activity release rate and radiation dose are also required. TS 3.8 also sets limits and conditions for fueled experiments that meet other TS requirements for experiments, the storage of fissionable materials, the facility emergency plan, and the facility security plan.

TS 4.4 is revised to include surveillance requirements for monitors listed in TS 3.5 and testing and maintenance of filters used in vented fueled experiments. - Fueled Experiment Analysis provides the bases, assumptions, data and supporting calculations required to justify the requested limits for fueled experiments. The bounding criteria are developed in Sections 1 through 9, providing detailed analyses of both accidental and planned vented 3

releases of fission gases and halogens, including radionuclides released, release pathways, and radiation dose from submersion, inhalation, and direct external exposure. The definition of a fueled experiment is given in Section 10, and Sections 11 through 15 provide supporting data, calculations, and conclusions.

The more restrictive of two release scenarios was used in determining the limiting conditions for fueled experiments;

1) A vented experiment in which the fission gases and halogens are continuously filtered, delayed, and then directly exhausted into the ventilation system over the entire duration of the experiment.

Or,

2) An accidental release from an encapsulation failure which then releases an instantaneous puff of fission gases and halogens into the reactor building and is subsequently ventilated by the reactor building confinement system for a period of 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. In this scenario, the fueled experiment irradiation is assumed to end at the initiation of the accidental release due to the activation of the confinement system.

Table 1 (Ref. Table 151): Radiation Doses for Fueled Experiments for planned vented and accidental releases, as compared to 10 CFR Part 20 Limits Reactor Building Public Area Release Nuclide Thyroid TEDE TODE TEDE (rem) (rem) (rem)

Vented U235 0.004 0.003 Vented Pu239 0.0038 0.002 Accidental U235 0.02 0.62 0.00027 Accidental Pu239 0.025 0.75 0.0003 Dose Limits for Fueled Experiments 0.15 1.5 0.003 (1) (2) 10 CFR Part 20 Limits 5.0 50 0.1(3)

(1)

Total Effective DoseEquivalent (TEDE) Annual Limit for occupationally exposed radiation worker.

(2)

Total Organ DoseEquivalent (TODE) Annual Limit to the thyroid for occupationally exposed radiation worker.

(3)

TEDE Annual Limit to members of the public.

As a result of the analyses performed in support of this license amendment request, the following statements are made:

1) Given the low limits requested for fission rates and total fissions for fueled experiments, any doses arising from accidental or planned vented releases will be more than an order of magnitude below 10 CFR 20 limits.

2) Activity releases and/or radiation doses do not exceed the limits established for a reportable event or emergency action levels.

3) Amounts of material requested and associated fission product activity does not exceed 10 CFR Part 37 Category 2 limits.

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4) Fissionable materials will continue to be stored as required by the R120 Reactor License and Technical Specification, the facility Physical Security Plan and the Radiation Protection Program.

5) No changes are required to the approved facility Emergency Plan, Security Plan, or Radiation Protection Program.

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DISCUSSION OF R120 LICENSE CHANGE To meet planned experiment needs, a change to Section 2.B.(2) of the R120 reactor license is requested to allow for possession of materials to be used in fueled experiments. Possession limits of 34 grams of Uranium235, 1 gram of Neptunium237, and 5 grams of Plutonium239 for fueled experiments is requested.

Radionuclides initially present and those produced by activation of Uranium with subsequent decay include:

Uranium: U234, U235, U236, U237, U238, U239 Neptunium: Np237, Np238, Np239 Plutonium: Pu238, Pu239, Pu240 The possession limits are based on mass rather than enrichment. Any enrichment may be possessed for fueled experiments up to the mass limits requested. Experiments may use high enriched material.

The 2 grams currently allowed for foils in 2.B.(2) has been incorporated into the 34 gram mass limit of Uranium requested for License Change in 2.B.(2).

Requested Change to 2.B.(2):

Pursuant to the Act and 10 CFR Part 70, "Domestic Licensing of Special Nuclear Material,"

to receive, possess, and use in connection with operation of the reactor up to 25 kilograms of contained uranium235 enriched to les s than 20 percent in the isotope uranium 235 in the form of reactor fuel; up to 20 grams of contained uranium235 of any enrichment in the form of fission chambers; up to 2 grams of contained uranium235 of any enrichment in the form of foils up to 34 grams of Uranium235, 1 gram of Neptunium 237, and 5 grams of Plutonium239 for fueled experiments; up to 200 grams of plutonium 239 in the form of plutoniumberyllium neutron sources; and to possess, but not separate, such special nuclear material as may be produced by the operation of the facility.

DISCUSSION OF TECHNICAL SPECIFICATION CHANGES TS 1.2.9.e - Fueled Experiment The current definition of a fueled experiment was revised to clarify what is classified as a fueled experiment. The new definition exempts samples or materials containing small amounts of uranium and is discussed in detail in Section 10 and Calculation 9 of Attachment 1 - Fueled Experiment Analysis.

Fueled experiments are defined for experiments involving the neutron irradiation of uranium above the limits for fission rate and total number of fissions. These limits were calculated for experiments containing uranium based on limiting the radiation dose from a potential release to one percent (1%) of the annual public dose limit given in 10 CFR Part 20, i.e. a TEDE of 0.001 rem. Experiments involving the neutron irradiation of uranium below these limits for fission rate and total number of fissions are not classified as fueled experiments. The neutron irradiation of any amount of any other fissionable material is a fueled experiment. All vented experiments that are designed to release fission gases and halogens are classified as fueled experiments.

Exclusions are given for experiments that do not involve a neutron fluence. The hazard with fueled experiments is the production and release of fission products. If no fissions occur, then the radiologic 6

hazard is no longer present. An example of the fissionable material not subjected to neutron fluence is utilization of the Positron Beam Facility spectrometers at the NCSU reactor, which have no associated neutron fluence and may be used to evaluate samples containing fissionable materials. Handling precautions and other controls are observed for any experiment sample.

Detectors containing fissionable material, such as fission chambers, which are used in the operation the reactor or reactor experimental facilities are not classified as fueled experiments. Sealed sources as defined by IAEA are sources encased in a capsule designed to prevent leakage or escape of the material from the intended use of the source or potential minor mishaps. Examples of sealed sources that meet the IAEA definition are sources with registration certificates generated by the NRC and Agreement States, special form radioactive material as defined in 10 CFR Part 71, and NRC approved reactor fuel elements in cladding are examples of such excluded materials.

TS 3.5 - Radiation Monitoring Equipment TS 3.5 was changed to include monitoring of the vented fueled experiment exhaust for radioactivity and flow rate.

Two instruments for vented fueled experiments were added to TS 3.5:

1. The vented fueled experiment exhaust gas radiation monitor is added as a requirement to verify compliance with TS 3.8. Fission gas (Kr and Xe) activity released from a vented fueled experiment provides an immediate assessment of compliance with TS 3.8 due to the mobility of noble gases.

Also, radioisotopes of Kr and Xe represent the major contribution to public dose from the expected release as analyzed and therefore are the major concern.

2. The vented fueled experiment exhaust gas flow rate monitor is added as a requirement to verify compliance with TS 3.8.

Footnotes (6), (7), and (8) are revised. Footnote (6) provides the value for the fission gas Airborne Effluent Concentration (AEC). Footnote (7) provides the flow rate measurement units. Footnote (8) indicates additional monitors needed for vented fueled experiments.

Setpoint changes in Table 3.51 are based on the effluent from a vented fueled experiment for the vented fueled experiment exhaust gas and particulate and gas building exhaust (stack gas and stack particulate) monitors. The new alarm and alert set points for the stack monitors given in Table 3.51 are based on meeting TS 3.8. All new alarm setpoints are lower than those currently used and are based on not exceeding a potential public TEDE of 3 mrem from a vented fueled experiment. The alert is based on a potential public TEDE of 2 mrem from a vented fueled experiment and was chosen to avoid the unintended initiation of the confinement system from a planned and analyzed vented fueled experiment.

Details on the new setpoints are provided in Calculation 10 of Attachment 1 - Fueled Experiment Analysis.

The bases of TS 3.5 was changed to include a brief discussion of the vented fueled experiment monitors and revised setpoints.

Detection of releases below the limits for notification of unusual event Emergency Action Level (EAL) continues to be provided. Exceeding the alarm set point initiates the confinement system and isolates the exhaust from a vented fueled experiment. Due to detector response and use of the confinement system the radiation dose to the public would be less than 3 mrem.

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TS 3.8 - Operations with Fueled Experiments TS 3.8 requires monitoring of the vented fueled experiment exhaust for radioactivity and flow rate when a vented fueled experiment is being performed. TS 3.5 and TS 4.4 are revised to meet TS 3.8 monitoring and surveillance requirements for vented fueled experiments.

TS 3.8 provides limiting conditions for operation for fueled experiments and is revised to establish upper limits for the allowable fission rate and total number of fissions. The upper limits on fueled experiments are established based on three percent (3%) of the annual radiation dose limits given in 10 CFR Part 20 as determined from the more restrictive of two release scenarios;

1) A vented experiment in which the fission gases and halogens are continuously filtered, delayed, and then directly exhausted into the ventilation system over the entire duration of the experiment.

Or,

2) An accidental release from an encapsulation failure which then releases an instantaneous puff of fission gases and halogens into the reactor building and is subsequently ventilated by the reactor building confinement and evacuation system for a period of 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. In this scenario, the fueled experiment irradiation is assumed to end at the initiation of the accidental release due to the activation of the confinement and evacuation systems.

TS 3.8 requires controls to prevent accidental releases associated with a failure of the fueled experiment encapsulation. If planned vented releases are needed for a fueled experiment, TS 3.8 requires additional controls to limit the release rate and radiation dose. TS 3.8 also sets limits and conditions for fueled experiments that meet other TS requirements for experiments, the storage of fissionable materials, the facility emergency plan, and the facility security plan.

Radiation doses are controlled, as stated in Attachment 1, by the following:

Minimum requirements for containers or encapsulation.

Radiation monitoring of the stack effluent and vented experiment exhaust.

Filtration and delay of the vented experiment exhaust gas.

Conservative dose calculations to occupants inside and outside the reactor building.

Requirements of TS 3.8.a through TS 3.8.f are explained in the bases as follows:

1) Specification 3.8.a requires all specifications pertaining to experiment reactivity given in TS 3.2 be satisfied thus ensuring that reactivity control of the reactor will be maintained.

2) Specification 3.8.b requires specifications TS 3.5 and TS 3.6 pertaining to the radiation monitoring and ventilation system be satisfied thus ensuring that a public dose of 3 mrem will not be exceeded should an accidental release occur during irradiation and/or handling of a fueled experiment.

3) Specification 3.8.c requires all specifications pertaining to limitations on experiments given in TS 3.7 be satisfied thus ensuring that fueled experiments also meet the requirements for all experiments.

4) TS 3.8.d provides limitations for fissionable materials used in fueled experiments.

a. TS 3.8.d.i lists the physical forms allowed in fueled experiments.

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b. Specification 3.8.d.ii limits the fission rate allowed in fueled experiments based on limiting the radiation dose from the release of fission products to a Total Effective Dose Equivalent (TEDE) of 0.003 rem in public areas outside the reactor building, a TEDE of 0.15 rem inside the reactor building, and a Total Organ DoseEquivalent to the thyroid (TODE) of 1.5 rem inside the reactor building. Radiation doses were calculated as described in Attachment 1.

c. Specification 3.8.d.iii limits the total number of fissions allowed in a fueled experiment based on the production of longlived fission products to levels below those given for Category 2 Quantities of Concern in 10 CFR Part 37. Radioactivity produced was calculated as described in Attachment 1.

d. Specification 3.8.d.iv provides controls for planned releases from vented experiments needed to ensure that radiation dose does not exceed three percent of the annual radiation dose limits given in 10 CFR Part 20. Radiation doses were calculated as described and presented in Attachment 1. A footnote to TS 3.8.d.iv was added to specify the required filter removal efficiency. The certification requirements are described in Attachment 1.

5) Specification 3.8.e requires all specification pertaining to criticality control given in TS 5.3 be satisfied thus ensuring that fueled experiments are stored in subcritical configurations.

6) Specification 3.8.f requires specification TS 6.2.3 and 6.5 pertaining to the review and approval of experiments be satisfied thus ensuring that fueled experiments are reviewed, approved, and documented as required.

TS 4.4 - Radiation Monitoring Equipment TS 4.4 is revised to include annual calibration of the vented fueled experiment exhaust gas radiation monitor and flow rate meter. Certification of iodine adsorption and periodicity of adsorbent filter replacement were also added to TS 4.4.

Annual calibration is based on calibration frequency for other monitors. Annual calibration includes a channel calibration for these monitors to test isolation of the experiment exhaust, initiation of the confinement filters, and Control Room annunciation.

Filter removal efficiency shall be certified by the supplier to be 0.95 or greater at flow rates at 3 lpm or less. The replacement time of 2 years, up to 30 months, is consistent with TS 4.5 for confinement system filters and is based on a shelf life of up to 5 years and noting that the exposure and operating characteristics to the confinement filters is similar. To meet LCOs for operation and surveillances, the confinement filters are continuously available for use and operated for a few minutes every week. The reactor building air is low relative humidity and at room temperatures, which is similar to the conditions for the vented fueled experiment exhaust.

Weekly setpoint verification is not changed in TS 4.4. This verification continues and applies to all equipment listed in TS 3.5.

Bases:

The bases of TS4.4 was changed to include the monitors used for vented fueled experiments.

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