ML20153F792
| ML20153F792 | |
| Person / Time | |
|---|---|
| Site: | 07001100 |
| Issue date: | 08/29/1988 |
| From: | Bidinger G, Swift J NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| To: | |
| Shared Package | |
| ML20153F776 | List: |
| References | |
| NUDOCS 8809070477 | |
| Download: ML20153F792 (3) | |
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AUG 2 9 1988 DOCKET NO: 70-1100 LICENSEE: Combustion Engineering Inc. (CE)
Windsor, Connecticut
SUBJECT:
SAFETY EVALUATION REPORT, REVISED LICENSE AMENDMENT APPLICATION DATED AUGUST 16, 1988, AND SUPPLEMENTS DATED AUGUST 19, AND AUGUST 23, 1988 RE PROCESSING URANIUM ENRICHED UP T0 5.0 WEIGHT PERCENT IN THE U-235 ISOTOPE
Background
CE is currently authorized to process uranium enriched up to 4.1 weight percent in the U-235 isotope. On January 20, 1988 CE submitted an amendment application to increase the U-235 enrichment to 5 weight percent. Following two meetings between CE and NMSS staffs. CE resubmitted the application on
- July 28, 1988. During the review of the July 28, 1968, submittal, numerous consents were given to CE by phone. On August 16, 1988, CE resubmitted the application ir its entirety. On August 19, 1988 CE supplemented the application to accommodate additional staff concerns and to facilitate implementation of new license requirements. On August 23, 1988 CE requested a 30 day delay for modification of the belt dryer.
Discussion Under the existing license CE receives uranium oxide powder which is fabricated into pellets. The pellets are clad in fuel rods and manufactured into fuel assemblies. CE can also receive >ellets which are clad in fur.31 rods and manufactured into fuel assemblies. Witi the proposed amendment, the process will not change. Process equipment changes involve replacing plastic containers with steel 5-gallon containers for powder handling, a different size hopper on the pellet press, and a modified belt dryer.
The basic health physics program will not be revised due to thee maximus U-235 enrichment going from 4.1 weight percent to 5.0 weight percent. The small increase in s pecific activity of the higher enriched uranium can be accommodated my the existing health physics program.
The basis for nuclear criticality safety has been changed significantly. One of the basic process units is 35 kilograms of U0 in a 5-gallon steel container.
Safety of the unit is basec on limited volume, l$aited mass, and a steel walled container. This unit will be spaced in arrays by a modified-surface-density method. CE did not show that the unit meets the "fraction critical" requirement for the surface density method, but did show that the array k-effective was i less than 0.95.
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AUG 2 0 1988 Cmbustion Engineering, Inc., Ser 2 A second basic unit is a 4-inch slab for powder or randomly-packed pellets.
The safety of this unit with pellets is based on limiting the maximum diameter of 1he sintered pellet to not more than 0.4 inches and randomly stacking the pellets so that the slabs would be under moderated if water or other hydragenous material leaked into the containers forming the slab. The random stacking is important so that no trays or other materials fonn gaps which which allow an increase in the water / fuel volume ratio.
CE did not establish controls to provent moderating material being placed between pellet trays within the 4-inch slab. Accordingly, the statf recorr.nends the following license condition:
Hydrogenous materials shall not be stored on pellet storage tables or pellet storage racks where nuclear criticality safety is based on 4-inch safe slab limits.
The other new criticality control unit is a 6-inch slab of fuel rods. The rods will be stacked on an in-contact diagonal pitch. This rod arrangement assures that the slab would be less than optimally moderated if flooded by water or other hydrogerous material. The licensee failed to consider the rnoderating effect of hydrogenous material placed between trays of rods within the 6-inch slab. To correct this oversight, the staff recommends the following license condition:
Hydrogenous materials shall not be stored betesen trays of fuel rods on storage racks or shelves where nuclear criticality safety is base on 6-inch safe slab limits.
In Part II, Chapter 8, CE described the process and provided a safety demonstration. Chapter 8 has been revised to allow for the higher uranium enrichment and to describe process steps which were ongeing but not previously described in the Chapter. Notable discrepancies exist between Chapter 4 and Chapter 8 in that safe units are described in Chapter 8, but are not described in Chapter 4, and hence, would not be authorized by the license. To resolve this issue on an interim basis, the staff proposes to incorporate Chapter 8 Part II into the license. This allows CE to process the higher enrichment in accord with their production schedule, but takes away the flexibility of cFain inplant changes. CE can regain the authorizatiun to make changes by eliminating the discrepancies.
Units which are discussed in Part II, Chapter 8, include the safe volute centrifuge and sump for grinder coolant, the safe diameter liquid waste collection cylinder, and the scrap recycle processes which are based on mass control (but not the concurrent 5-gallon volume control.)
It should be noted that CE has incorporated part of Part II, Chapter 8, into the license conditions section. For example Section I.4.3.14 specifies storage of fuel assablies will be in accordance with Figure 8.11 Part II.
Hence the incorporation of all of Chapter 8 is not a severe limitation for CE.
AUG 2 9 1988 Combustion Engineering, Inc., Ser 3 In the letter dated August 19, 1988, CE requested a condition which would allow 3 months to phase out the poly containers currently in use. These containers would be used only for uranium enriched up to 4.1 weight percent.
The staff agrees to this condition.
In the letter dated August 23, 1988 CE requested a 30-day exemption for 4
installation of the dryer belt modification. Daily inspections will be 5
performed to detect uranium buildup under the belt. The staff agrees to the request provided that records of inspection and cleanout are maintained for six months following termination of this exemption.
Conclusion /Recouendation The staff concludes that CE ccn process uranium enriched up to 5.0 weight 1 percent in the U-235 isotope. The license amendment application is incomplete and certain license conditions identified by the staff and by CE are necessary. Subject to these license conditions, the staff recomends approval of the application.
The Region I staff has no objection to this proposed action.
@ Sig M d %
George H. Bidinger Uranium Fuel Section
- l Fuel Cycle Safety Branch Division of Industrial and gg Medical Nuclear Safety, NMSS '
! Approved by:
! Jerry J. Swif t, Section Leader l
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