ML20045H148
| ML20045H148 | |
| Person / Time | |
|---|---|
| Site: | Framatome ANP Richland |
| Issue date: | 07/09/1993 |
| From: | Maas L SIEMENS CORP. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| IEB-91-001, IEB-91-1, NUDOCS 9307190129 | |
| Download: ML20045H148 (2) | |
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SI.EM ENS July 9,1993 U.S. Nuclear Regulatory Commission Document Control Desk Washington, DC 20555 Gentlemen:
Follow-Up to Bulletin 91-01 Report on Line 1 Process Ofigas (POG) Scrubber Separator Unit - NRC Report Number 25632 On June 9,1993, Siemens Power Corporation (SPC) reported a condition that met the reporting requirements of NRC Bulletin 91-01. SPC internal procedures require a 30-day written follow-up report to all Bulletin 91-01 reportable conditions or events. This letter meets this requirement.
I Backctround Siemens Power Corporation operates two UF to UO, conversion lines. Each line has a g
separate offgas system which includes two scrubbera and moisture separators. The solution from the offgas scrubber system typically contains only a few grams of uranium per liter. This solution is recycled into the process through lines back to favorable geometry tanks.
One of the criticality safety controls specified by the Line 1 POG scrubber criticality safety analysis was for the moisture separator to contain less than 2 liters of liquid on a double contingency basis.
Description As part of an ongoing program to update the criticality safety analyses at SPC, SPC personnel identified that insufficient controls were in place to assure meeting a 2 liter solution volume limit in the Line 1 POG moisture separators as required by the criticality safety analysis for Line 1. A nearly identical POG design is used on Line 2. The criticality safety analysis for Line 2 allows a 6 inch solution depth in a moisture separator with identical dimensions. This CSA was reviewed and determined to be equally applicable to Une 1.
The Line 1 system was immediately shut down until the criticality safety analysis could be addended to allow a 6 inch solution depth and until a secondary overflow line to ensure compliance with this depth could be added.
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' July 9,1993 A telephone report to NRC headquarters was made at 1853 hours0.0214 days <br />0.515 hours <br />0.00306 weeks <br />7.050665e-4 months <br /> PST on June 9,1993 in accordance with NRC Bulletin 91-01. This report was made because of insufficient controls on a controlled parameter, discovered as part of SPC's ongoing CSA update program. There was no evidence at the time of discovery of the condition that the solution volume limit in the moisture separator was actually being exceeded. Furthermore, a relevant criticality safety analysis for Line 2 indicates that the operation is safe.
Due to the low uranium concentration in the solution in this system and the three inch drain line in the bottom of the moisture separator to prevent significant solution depth, a criticality accident in this system was not possible.
Cause and Lona Term Corrective Actions The cause of this condition was an inadequate failure modes and consequences analysis while preparing the original analysis.
The long term corrective actions for the system design included adding secondary overflow lines on the moisture separators to ensure that the allowed depth will not be exceeded. The CSA has been addended to reflect appropriate limits and controls. The long term corrective action for the inadequate CSA will be completed via the ongoing program to update the criticality safety analyses at SPC.
Questions regarding SPC actions in response to this condition can be directed to me on 509-375-8537.
Very truly yours, Wu Quv L J. Maas, Manager Regulatory Compliance LJM:pm cc:
B. Faulkenberry, NRC Region V