ML20029C432
| ML20029C432 | |
| Person / Time | |
|---|---|
| Site: | 07001100 |
| Issue date: | 03/20/1991 |
| From: | Bidinger G, Robinson C, Soong S NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| To: | |
| Shared Package | |
| ML20029C430 | List: |
| References | |
| NUDOCS 9103280156 | |
| Download: ML20029C432 (3) | |
Text
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[p ua u
o UNITED STATES 8'~
'n NUCLEAR REGULATORY COMMISSION
- e WASHINGTON, D. C. 20555
.s
'l MAR 2 01991
%.... /
DOCKET NO:
70 1100 LICENSEE:
Combustion Engineering, Inc. (CE)
Windsor, Connecticut
SUBJECT:
SAFETY EVALUATION REPORT, AMENDMENT APPLICATION DATED OCTOBER 25, 1990, AND SUPPLEMENTS DATED FEBRUARY 13, AND MARCH 5, 1991, RE OPERATION OF THE CENTRIFUGE SYSTEM
Background
Since early 1970, CE has used a centrifuge system to reduce the radioactivity level of liquid waste prior to transferring it to liquid retention tanks.
Cy letter dated September 13, 1990, CE informed the NRC of plans to relocate the centrifuge system from its present location in the pellet shop to the pellet shop annex. By letter dated September 28, 1990, CE was informed that a license amendment would be required to operate the centrifuge in the new location.
By amendment application dated October 25, 1990, CE requested authorization to operate the centrifuge system. By letter dated January 14, 1991, the NRC staff requested additional infnrmation be nrovided. On January 21, 1991, CE provided pictures of the centrifuge system.
response to the staff's request, by letter dated February 13, 1991, CE prc ded revised pages for the license.
After telephone conversations with the
'aff on March 1 and March 4, 1991, CE supplemented the application by letter
- ed March 5, 1991.
Discussion Radiation Safety j
i The proposed activity involves the relocation of the centrifuge. Accordingly, the staff has determined that CE's current radiation safety program is adequate i
to protect the health and safety of the workers and the public.
Nuclear Criticality Safety The licensee submitted a nuclear criticality safety analysis for the centrifuge system (liquid waste processing system) located in Building 17. Particulate radioactive material (RAM) is removed from the aqueous stream by a filter and centrifuge. The aqueous stream is sampled for radioactivity and, if below a threshold level, transferred to the retention tanks in Building 6.
The centrifuge system consists of the following equipment:
dump tank with filter and pump, centrifuge and hood, slant storage tank (SST), overflow tank, spill pan, recirculation pump, discharge pump, and both manual and solenoid valves. The basic prorass parameters for the process equipment include vessels with a maximum volume of 5 gallons or slabs with a maximum thickrrss of-4 inches.
Safety of these units is based on f avorable geonietry. The SST is. slab tank whien is structurally reinforced and vented to prevent a change in ',ts intended shape or dimens1ons resJlting from bulging.
J 9103280156 910320
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PDR ADOCK 0700 0
I Combustion Engineering, Inc.
2 2 0 1991 8
For a heterogeneous system under optimum conditions (moderation, reflection, particle size, and distribution), the 5-gallon vessel volume exceeds the safe volume but is less than the critical limit.
Similarly, for a heterogeneous system under optimum conditions, the 4-inch slab exceeds the safe slab thickness but is less than the critical limit.
Thus, without'the use of addi lonal controls, the systems do not poss6ss an adequate safety margin for heterogeneous material.
Controls have been implemented to limit the increased reactivity effects of heterogeneity and reflection within the centrifuge system. Hetarogeneous systems are generally defined as any mixture with uniformly distributu particles larger then 1 mm. The exclusion of heterogeneity provides positive suberiticality, thus a prefilter is utilized to remove 'particulates greater than 1 mm. A screen barrier is employed to prevent close reflection _on the SST's slab faces.
S'olids accumulation within the system are controlled by use of the limits for dirty s: rap as specified in the license.
In particular, the 16 kg mass limit and the spacing provisions establisNd in Tables 4.2.5 and 4.2.6 of the license will be used when extracting solids from the liquid waste processing system.
Implementation of the double contingency plan is adequately satisfied by performing dual, independent verificauon.of the RAM content within the aqueous stream. _ The aqueous stream is sampled and analyzed-twice for residual cortamination prior to release to the retention tanks which are not geometrically safe ulumes. One sample is taken from a sample port located on the 1 circulation loop. This loop circulates the aqueous-stream through the_ centrifuge and SST..
The other sample is taken directly in the SST prior to discharging the tank contents. A separate discharge line provides for flow between the SST and-Building 6 retention tanks.
The two samples are measured by identical means but are collected independently since the recirculation loop and SST effluent are isolated from one another.
The independent collection is accomplished by segregating the recirculation loop from the SST with both manual and solenoid e.@s and by employing separate pucps for feeding, recirculating, and discharging t % equeous stream. The dump tank pump, which introduces RAM to the system, anf the discharge pump are interlocked to prevent the simulataneous operation of then p Aps. 'In addition, soltnoid valves on tae recirculation loop and discharge G ne~are interconnected with the discharge pump so that the loop stream cannot enter the effluent stream during discharge.
The centrifuge system is located under a stairway. Tc preclude a critical' condition caused by the approt:h of fissile material in transit, a sheet metal barrier will be installed around the stairway. The staff has evaluated various scenarios concerning the neutronic interactions between the centrifuge system and SNM porterage. The staff's analysis of this situation confirms CE's conclusion that interactions between material passing up the stairway, resting upon the steirway, or spilled upon the sheet metal result in acceptable calculated subcriticality margins' l
l o
. MAR - % 0 - 1991 Combustion Engineering, Inc.
3 N
Adherence to-the-limits and-controls established in the license and proposed in this amendment application is sufficient to ensure suberiticality within.
the centrifuge system.
Conclusion /Recommandation.
j Based on the above discussion, the staff concludes.that the proposed _ amendment l
L can be issued without undue-risk to the workers, public, or environment?
Therefore,-the staff recommends that the amendment be approved.
The Region 1 Principal: Inspector has no otat:: tion to this proposed ~ action.
Original Signed BT.
Onginal Signed Br Chuck Robinson
- Sean Soong-Uranium Fuel Section Uranium Fuel.Section-Fuel Cycle Safety Branch
-Fuel Cycle Safety Branch-Division of Industrial:and
. Division of. Industrial and-l-
l Medical Nuclear Safety, NMSS Medical 1 Nuclear Safety', NMSS l
D W $gned Br_
Approved by:
George H. Bidinger,-Section Leader SS/701100 CE SER-AMD 21 l
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'VLTharpe GH8idinger:
- DATE:3/jf/91:-
3//7/91:
' 3/AD/91.
3/ oc/91: -
-uFFICIAL RET 0lb COPY.
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