ML20199L582
| ML20199L582 | |
| Person / Time | |
|---|---|
| Site: | Portsmouth Gaseous Diffusion Plant |
| Issue date: | 11/26/1997 |
| From: | Morgan J UNITED STATES ENRICHMENT CORP. (USEC) |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| 70-7002-97-203, GDP-97-2037, NUDOCS 9712020059 | |
| Download: ML20199L582 (5) | |
Text
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Enrichment CorporItion 2 Democracy Center 6903 Rockledge Drwe Dethesda. IAD 20<.17 Tel (301)564 3200 F ax: 13011564-3201 l'niini ales l'urichinent (hijoration November 26,1997 United States Nuclear Regulatory Commission GDP 97 2037 Attention: Document Control Desk Washington, D.C. 20555 Portsmouth Gaseous Diffusion Plant (PORTS)
Dockei No. 70-7002 Revised Response to Notlee of Violation (NOV) 97 203-03 USEC letter GDP 97 2015 provided a response to NOV 97-203-03 regarding the failure to properly validate Nuclear Criticality Safety (NCS) computer code calculations. In this response, USEC denied the violation based on our belief that the SCALE code was adequately validated for the NCS calculations. Nuclear Regulatory Commission (NRC) letter dated October 28,1997, rejected USEC's response because, in NRC's opinion, it did not provide aro' additional technical basis that the SCALE code is validated in the intermediate range, or demonstrate that the code is well behaved between 5% and 92.5%
Aner further review of this issue, USEC acknowledges that benchmark data was not used this violation. Accordingly, Enclosure 1 to this Lter provides the reason f to validate SCALE code calculations in the intermediate range. Therefore, USEC no longer contests -
actians taken, corrective actions to be taken, and the date when full compliance will be achieved.
USEC continues to believe that the SCALE code calculation yields valid results for the 20%
enrichment cases. The correctness of this approach was recently confirmed with the authors of this code [(i.e., DOE Oak Ridge National Laboratory (ORNL)].
As requested in NRC's letter dated October 28,1997, USEC has scheduled a meeting with NRC on December 8,1997, to further discuss this issue and to reach a common understanding as to the action required to achieve resolution.
Following this meeting, USEC will submit a supplemental response to this NOV by January 14,1998.
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a United States linriclunent Corporation November 26,1997 Page Two linclosure 2 lists the commitments made in this letter, if you have any questions regarding als submittal, please contact Ron Gaston (614) 897 2710.
Sincerely, Vames 13. Mor n
Acting General Manager Portsmouth Gaseous Diffusion Plant linclosures (2) cc:
NRC Region 111, Regional Administrator NRC licadquarters, Chief Fuel Cycle Operations Branch. NMSS (P. Ting)
NRC Resident inspector, PORTS
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UNITED STATES ENRICllMENT CORPORATION (USEC)
REVISED RESPONSE TO NOTICE OF VIOLATION (NOV) 97 203-03 Restatement of Violation I
TSR Section 3.11.1 requires, in part, that "A Criticality Safety Program shall be established, implemented, and maintained as described in the Safety Analysis Report...".
S AR Section 5.2.3.2 requires, in part, that "When NCS is based on computer code calculations of K,.n, controls and limits are established to ensure that the maximum K,ncomplies with the applicable i
code validation for that type of system being evaluated."
Contrary to the above, as of May 30,1997, three Nuclear Criticality Safety calculations, NCS-CALC-97 06), NCS-CALC.97-010, and NCS CALC.97 012, were observed to be based upon an enrichment of 20%, without justification that the results are bounded by the validation report.
I.
Reason for the Violation The reason for the violation was that no benchmark data existed to support the SCALE code validation in the intermediate range at the time the validation report was prepared. Ilowever, USEC believes using the SCALE code i<
.id in the intermediate range and USEC is currently assembling data to verify the cc ness of this approach. Additionally, based on discussions with the authors of this ou (i.e., DOE ORNL),USEC believes that the theoretical aspects of the code not yet validated do not pose a risk of criticality, 11, Corrective Actions Taken and Results Achieved As noted above, USEC has contacted DOE ORNL concerning the validity of using the SCALE code calculations for the intermediate enrichments. DOE's reply was documented in a memorandum dated November 21,1997. The DOE memorandum states that while the criticality codes and cross sections have been validated over a broad range of moderation for enrichments <5% and >90%, the validation is also applicable to systems which are "similar" (e.g., geometry, fuel type, moderator, moderation range) to those that have been validated.
Therefore, DOE stated that the validation could be applied to intermediate range enrichments where optimum moderation for minimum mass or solution geometry is considered.
Additionally, DOE concurred additional data is needed for validation of calculations that are going to be performed for systems at intermediate enrichments.
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II.
Corrective Steps to be Taken 1.
USEC is currently assembling benchmark data applicable to the intermediate enriclunent range for NCS code validation efforts associated with the Atomic Vapor Laser Isotopic Separation (AVL 1S) project. The collected data will be reviewed for applicability and included in the validation report.
2.
Following the completion of the abos e action, existing NCSAs and their supporting calculations will be reviewed to determine the impact the data validation results may have on them. These NCSAs and their supporting calculations will 'cc revised as needed.
3.
USEC has scheduled a meeting with NRC on December 8,1997, to further discuss this issue and achieve resolution.
4.
USEC will submit a supplemental response to NRC by January 14,1998, based on the inclusion of the new benchmark data in the validation report.
IV.
Date of Full Compliance The date by which USEC expects to achieve full compliance will be provided in the supplemental response.
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UNITED STATES ENRICilMENT CORPORATION (USEC)
REVISED RESPONSE TO NOTICE OF VIOLATION (NOV) 97 203 03 LIST OF COMMITMENTS 1.
USEC is currently assembling benchmark data applicable to the intermediate enrichment range for NCS code validation cfTorts associated with the Atomic Vapor Laser Isotopic Separation (AVLIS) project. The collected data will be reviewed for applicability and included in the validation report.
2.
Following the completion of the above action, existing NCSAs and their supporting calculations will be reviewed to determine the impact the data validation results may have on them. These NCSAs and their supporting calculations will be revised as needed.
'3.
USEC will submit a supplemental response to NRC by January 14,1998, based on the inclusion of the new benchmark data in the validation report.
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