ML20023D663
| ML20023D663 | |
| Person / Time | |
|---|---|
| Site: | 07000371 |
| Issue date: | 05/18/1983 |
| From: | Bidinger G NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| To: | |
| Shared Package | |
| ML20023D662 | List: |
| References | |
| NUDOCS 8305250607 | |
| Download: ML20023D663 (5) | |
Text
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O FAY 181983 DOCKET NO.: 70-371 LICENSEE:
United Nuclear Corporation (UNC)
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FACILITY:
Montville, Connecticut
SUBJECT:
SAFETYEVALUATIONREPORT(SER)-AMENDMENTAPPLICATION DATED MARCH 21,1983 AND REVISIONS DATED MAY 5 AND MAY 12,1983 REQUESTING AUTHORIZATION TO FABRICATE FUEL ELEMENTS USING NEW INDIVIDUAL UNIT AND SPACING REQUIREMENTS, 07000371060S I.
Background
In the original amendment application, UNC requested, approval of safe individual unit and spacing requirements for fabricating two new fuel elements, a new safe individual unit, spacing requirement for one process step in fabricating a conventional fuel element, and new spacing requirements for a 350 g U-235 unit.
In the revised application;WAC corrected the U-235 limits for the two fuel elements, corrected dimensions of one element, demonstrated that double batching of the wGder is not feasible, provided for measurement of U-235 in sHe mass (350 g U-235) units, and corrected the reference to justify the spacing for the 350 g U-235 unit.
II. Discussion A.
Process Description / Safety UNC plans to fabricate fuel elements by a new formation and cladding process. One step in the process will be done by another licensee at an offsite location. Transport of tnis material is discussed in the application, but is not being evaluated in this report. Formation of the Ause.tunt fuel elements will require use of hydrogenous material which will be removed by a solvent in a subsequent process operation.
The solvent removal process will be done in enclosures with an inert atmosphere. Monitors will be located inside and outside the enclosures to detect oxygen inside the enclosures and solvent outside the enclosures. Detection limits are set low engugh so that corrective actions can be initiated before explosive concentrations occur.
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, The feed material for this process has the same general
. physical. characteristics as other feed material used by UNC and provides no other process safety concerns. After element formation and cladding, the fuel element will be machined and inspected, using established processes and procedures.
The solvent will be filtered, sanitored and piped to separate buildings where the solvent will be treated for recycle.
B.
Nuclear Criticality Safety 1.
General UNC has proposed nuclear criticality safety limits for the process steps associated with the formation and cladding of the new fuel elements and new limits for an l
existing feel element. The fuel elements are described on Page 10.0-7C, Part 1 of the revised application dated May 5,1983.
2.
Establishment of Limits One of the nuclear criticality safety units will be 350 grams of U-235 4(tem 6. Table 3.9.5-1, Part I of the revised application, dated May 5,1983). This unit will be spaced so thAt the seell density will not exceed 175 grams U-235/ft'. A minimum spacing of 12 inches, edge-to-edge, will oe maintained between units. The NRC staff agrees that the siit size and spacinf are adequate for nuclear criticality safety.
The licensee has had a practice of estimating, rather than measuring, the quantity of U-235 in certain mass-limited scrap units. Because of MRC staff concerns, the licensee added a footnote to revised Page 3-31, Part I, dated May 5,1983, which rqquires the licensee
.te measure the U-235 centent of material prior to adding the material *chuch units.
The licensee has established maximum uranium mass limits for each operation (Items 1-5, Table 3.9.5.1, Part I of the revised application dated May 5,1983) such that the process unit wo&ld be suberitical if the unit were optian11y moderated and fully reflected. Safe minimum spacing between the units was demonstrated by assuming thateachunitorsystemofunits(i.e.,thedesiccators) would exist in an infinite planar array of similar units.
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MY I 81983 Each unit is further assumed to have optimum credible internal moderation and optimum interspersed moderation around the unit. The i
infinite array of units also was assumed to be reflected by a 16-inch concrete floor and a 4-inch concrete roof (10 feet above the floor). The licensee used KENO calculations to show that the reactivity of the individual fully reflected units and the reactivity of an infinite array of similar units would not exceed a k-effective limit of O.928, a reactivity limit previously established in the license. With this defined spacing for identical uditoin an infinita arrey, UNC would allow mixing of different units provided that the i
infinite array spacing for the particular unit is maintahed.
The NRC staff concludes that the methodology for setting safety limits is acceptable.
l 3.
Specific Analyses The basic components for the new type element will be formed and cleaned using the 350 gram U-235 safe mass unit.
These components will be dried in desiccators.
Double batching is not credible because desiccator trays are assened to be full and desiccator racks limit the nunter of tres. An infinite array of the desiccators in the plant with the above described assaned environment wod14 have a k-effective of 0.92.
The k-effective for desiccators with the basic component for the conventional element would be less.
The NRC calculated a k-effective of 0.88, by assuming that mist was present only around the desiccators.
The basic components of the new type element would then be processed through a furnace operation. The furnace has been evaluated with all trays filldd to capacity with the components. For the assumed environment, an infinite array of furnaces would have a t-effective of 0.74.
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' New-type elements will be loaded into a welding fixture. Double batching is not credible because the fixture is loaded by a machine with automatic indexing. The licensee calculated the k-effective for this unit in the assumed environment in the plant to be 0.91. The NRC staff calculations confirmed the licensee's value.
t The new-type elements and the conventional-type elements will be enclosed in steel alloy overpacks for a forming process. The steel serves as a nuclear poison in an array of the elements for the assumed environment in the plant such that no limit en, the neber of packs is required, i.e., k - inf = 0.86.
The NRC staff calculated that an infinitely long column of packs, reflected by water, would be suberitical.
The solvent used to clean the basic components of the new-type elements will be monitored, filtered, and piped to collection and process vessels in a separate building for solvent recovery. Follow 6ng discussion with the NRC staff, the licensee fevised.the application to require filtration and monitoring of the used solvent before it is m? eased to the solvent recovery building.
In the revised application, the licensee causitted to: inspecting the outside tanks three times a year. To assuee nuclear safety,-
the following license condition is recommended:
Used solvent shall not be released to the solvent recovery system until measurements in the inline monitor indicata that the uranium content in the solvent is less than 6 milligrams U-235 per liter. The inline monitor shall be calibrated at least every 4 senths. The solvent recovery tanks and process *vessHs shall be inspected for uranium buildup at least every 4 unnths.
If uranium buildup is detected. such urani a shall be removed before more solvent is transferred to the solvent recovery system.
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MAY 181983 The concrete floor is a thick and, hence, an effective reflector. For the ENO an&calations., different process units were assumed to be located at specified distances above the floor. At the mquest of the NRC staff, the licensee included these distances in Table 3.9.5.1 Part I, of the mvised application dated Nay 5,1983, as conditions of the license.
C.
Radiation Safety The feed materials and the fabrication processes are similar to existing materials and processes. As such, no unusual radiation protection risks exist. The current radiation
-sifety program should provide adequate protection to the l
.he414h and safety of the workers.
III. Conclusions / Recommendations The staff concludes that the proposed activities pose no undue risk to the health and safety of the public or to the environment.
Subject to the above license condition, approval of the amendment application is recomuended, v
G. H. Bidinger Uranium Process Licensing Section l
Uranium Fuel Licensing Branch I
Division of Fuel Cycle and Material Safety, NMSS
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Approved by-fAA-W. T. Creiw, section Leader J
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