ML20211G934
| ML20211G934 | |
| Person / Time | |
|---|---|
| Site: | Framatome ANP Richland |
| Issue date: | 09/23/1997 |
| From: | Weber M NRC |
| To: | |
| Shared Package | |
| ML20211G920 | List: |
| References | |
| NUDOCS 9710060060 | |
| Download: ML20211G934 (4) | |
Text
pm #80g UNITED STATES
_s D
NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 90nH001 September 23, 1997 i
DOCKET:
70-1257 i
LICENSEE:
Siemens Power Corporation Richland. WA
SUBJECT:
SAFETY EVALUATION REPOR7: AMENDMENT APPLICATION DATED MARCH 18. 1997, ROTARY VACUUM FILTER BACKGROUND In a letter dated March 18. 1997. Siemens Power Corporation (SPC) applied for a license amendment to use two (2) rotary vacuum filters (RVFs) in place of a centrifuge in its revised mop powder uranium recovery process.
The license amendment adds a new authorization of "Less than or equal to 18" nominal OD x 12" nominal length rotary vacuum filter" to Table 1-4.1 of SNM-1227. The i
application and supplementary information describe the criticality safety controls to be useci.
By letter dated April 15. 1997. SPC described in more detail the use of the RvFs. 0n April 16. 1997, the NRC issued a Request for Additional Information (RAI). SPC responded to the questions in the RAI in a letter dated May 21.
-1997 and provided su)plementary-information on June 6. 1997.
On June 16, 1997, the N?C issued a second RAI, SPC discussed the proposed amendment with the NRC at a meeting at NRC Headquarters on June 26. 1997, and at a meeting in Richland. Washington on July 1. 1997.
SPC responded to the questions in the second RAI in a letter dated July 10. 1997.
QlSCUSSION The staff has reviewed the information submitted by SPC and has performed a technical assessment of the Nuclear Criticality Safety Program associated with the use of two RVFs in the mop powder uranium recovery process to remove inert solids from solution.
The solids are dirt removed from the floor during normal cleaning operations in the conversion areas.
A single RVF is a right circular cylinder placed horizontally which, during operation.' rotates around a two-inch diameter center shaft.
The cylinder's outside edge is divided into six equally-sized sections lengthwise on the cylinder's surface whose bottoms are the cylinder's outside wall and whose tops are a polyprop)lene filter cloth.
Each of the six sections is connected to the central shaft via a 1-inch pi>e. A coating of diatomaceous earth (DE) is applied to the polypropylene cloti, and the DE becomes the actual filter media for the slurry. The filter center section is filled with a silicon rubber compound that contains sand and boron carbide to prevent liquid from 9710060060 970923'I~
.PDR ADOCK 0700 2 7
2 getting into the cylinder and to provide some neutron absorber to aid criticality safety, The cylinder is partially submerged inside a shallsw pan which contains the slurry to be filtered.
As the cylinder is slowly rotated, a vacuum is applied to the central shaft.
Liquid in the pan passes ' arough the DE and the filter cloth, through the one-inch pipes to the centcr shaft, through the center shaft, and then inta an evacuated receiver teri, bolids deposited on the cloth are cut off the surface with a fixed knife, then collected in small containers for additional uranium removal or disposal as low level radioactive waste.
For performing criticality safety analyses, Part I of SPC's license SNM 1227 requires assumed conditions of process variables to be at their credibly most reactive values.
These process variables include:
moderation, reflection, mass, concentration, density, enrichment, heterogeneity, geometry, and spacing.
Based on the staff's review. SPC has assumed the credibly mast-reactive conditions in the analysis.
Criticality Safety Controls This amendment adds a new com)onent to Table I 4.1 of the SPC license:
Less than or equal to 18" nominal CD x 12" nominal length rotary vacwm filter.
The types of criticality controls listed in Table I-4.1 for the nea emponent will be VOL (Volume Control). FNA (Fixed neutron absorber), and SPA (Control of spacing from other fissile units).
Model of the RVF system SPC used conservative values in its analysis, i.e., the type of fissile material and moderating material assumed were more conservative than what is present in normal operating conditions.
SPC also used the maximum U-235 enrichment allowable in the current license (5%).
Effectively, the SPC analysis was extremely conservative since it encompassed normal ooerating conditions and credible abnormal conditions.
Nuclear Analysis The neutron interaction analysis for the RVFs was performed by the NRC staff using KtNO V.a calculations.
KENO is a Monte Carlo neutronics code that can be used for calculating k-eff values for configurations of SNM at fuel cycle facilities.
The code uses probabilistic techniques to determine the results of neutron interactions.
From these results, the effective multiplication of neutrons can be computed.
When nuclear criticality safety is based on computer code calculations.
Chapter 4 of the SPC license requires the calculated (k-eff+2 sigma) value (including calculational bias) to be below certain limits for normal and credible abnormal conditions.
Using the 16-group cross-section set, the normal condition limit is 0.948, and the credible abnormal condition limit is 0.968.
3 l
Each RVF was analyzed by both SPC and staff using enrichment of 5.0 wt.% U 235 for the 00 powder, materials of boron-silicon for inside the RVF and UD, H O 3
2 for the RVF and pan.
The maximum amount of UO in the U0, H O mixture was 2
2 j
conservatively assumed to be 22%.
The 44 group cross section library was used i
to take advantage of the most recent available nuclear data.
The NRC staff investigated three physical models:
(1) a single RVF with a 17" pan (2) both RVFs with actual spacing with 17" pans, and (3) the room including both RVFs and all other equipment with actual spacing with 16" pans.
The calculated (k eff+2 sigma) values were:
(1) 0.92657. (2) 0.90274, and (3) 0.87348, res)ectively, The staff did not cordider it necessary to run scenario (3) witi 17" pans because the resulting)k eff was expected to be lower than that k eff resulting from scenario (1 and all :f SPC's studies at aan sizes ranging from 12" to 18" demonstrated that scenario (3) consistently lad k-eff values less than scenario (1).
Since the highest calculated value of 0.92657 was less than the normal condition limit of 0.948 and the assumptions used when analyzing the above scenarios were extremely conservative the use of two RVFs in the revised mop powder uranium recovery process is adequately safe.
CONCLUSION l
Based on information submitted by the licensee: commitments in Chapter 4 of its license concerning the use of passive, engineered, and administrative controls to prevent a nuclear criticality incident during normal operatim conditions: and the technical review, the staff has reasonable assurance that a nuclear criticality incident will not occur because no single failure will cause an inadvertent nuclear criticality incident, ENVIRONMENTAL REVIEW 1he staff has determined that the following conditions have been met:
1.
There is no significant change in the types, or significant increase in the amount. of effluents that may be released offsite.
2.
There is no significant increase in individual nr cumulative occupational radiation exposure.
3.
There is no significant construction impact.
4.
There is no significant increase in the potential for, or consequences from, radiological accidents Accordingly, pursuant to 10 CFR 51.22(c)(11) neither an environmental essessment nor an environmental impact statement is warranted for this action.
4 C.ONCLUSION The NRC staff has reviewed the proposed amendment and has determined that the proposed changes will have no adverse effect on the public health and safety or the environment.
Therefore, approval of the amendment application is recommended.
The Region IV inspection staff has no objection to this proposed amendment.
t ['e i 3rinci)al Contributors p
'iarry ). Felsher g,M
- s.
Kimberly J. Hardin Susan D. Chotoo 4k 1
1
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