ML20045J024
| ML20045J024 | |
| Person / Time | |
|---|---|
| Site: | Framatome ANP Richland |
| Issue date: | 07/15/1993 |
| From: | Maas L SIEMENS POWER CORP. (FORMERLY SIEMENS NUCLEAR POWER |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| IEB-91-001, IEB-91-1, NUDOCS 9307220311 | |
| Download: ML20045J024 (2) | |
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4 July 15,1993 U.S. Nuclear Regulatory Commission Document Control Desk Washington, DC 20555 Gentlemen:
Follow Up to Bulletin 91-01 Report on Grinder Water Centrifuge Reservoir - NRC Report Number 25662 L
On June 17,1993, Siemens Power Corporation (SPC) reported a condition that met the reporting requirements of NRC Bulletin 91-01. SPC internal procedures require a 30-day
. follow-up report to all Bulletin 91-01 reportable conditions or events. This letter meets this requirement.
Backaround Siemens Power Corporation has three UO2 Pellet grinder lines. The grinders on each of the three lines are used to grind pellets to the desired diameter. Water is supplied to the grinder wheels for cooling and for washing UO particles from the pellets and grinders. The grinder 2
line water systems are closed looped systems. Each grinder water loop includes a heat exchanger, two filters, a centrifuge, and a centrifuge reservoir.
One of the criticality safety requirements for the centrifuge reservoir is for the maximum solution depth to be limited to 8.0 inches. 'The approved design for this system included an overflow at 8.0 inches to assure this limit is met. The overflow line consisted of a pipe and an elbow to direct any overflow toward the floor.
Description As part of an ongoing program to update the criticality safety analyses at SPC, SPC -
personnel discovered that the elbow on the end of each of the centrifuge reservoir overflow lines had been turned upward. The depth of solution before overflow in this configuration is about 10 inches.
The system was immediately returned to the approved configuration and design changes were initiated to modify the. reservoir to include more positive methods of limiting the possible solution depth.
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Siemens Power Corporation-0 Nucicat Dwision - Eng:neering and Manufactunng FacMy 2101 Horn Rapids Road, PO Bo< 130 Richland. WA 99352 0130.-
Tel: (509) 3758100 Fax. (509) 3758402
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' July 15,1993 A telephone report to NRC headquarters was made at 1525 PST on 6/17/93 in accordance with NRC Bulletin 91-01 because of a degradation in a controlled parameter. The actual solution depth had, in fact, not been exceeded because the reservoir is equipped with functional level indication and operators are instructed to limit the solution depth to between 5 and 6 inches. Furthermore, the filtering system design and controls in place on the centrifuge operation make it very unlikely that even a safe mass (45% of minimum critical mass) of-uranium would be present in the centrifuge reservoir. For these reasons, a criticality _ accident in this system was not possible. K-eff at the 10 inch full configuration assuming optimum moderation and reflection was calculated to be 0.9658
.0044.
.Cause and Lona Term Corrective Actions The violation occurred when someone rotated the elbows to minimize periodic splash!ng of liquid out of the overflow and onto the floor. This rotation bad the effect of increasing the potential overflow depth of liquid in the tank to about 10 inches. The contributing causes of this condition include a failure of the original Engineering Change Notice to specify the required orientation of the elbow and failure of the maximum overflow height of 8 inches to be specified in a visible and frequently reviewed location.
The long term corrective actions included adding dual overflow drains at a lower level and providing internal baffles to eliminate spills from the overflow due to splashing. Furthermore, Siemens is currently undertaking a comprehensive update of the Criticality Safety Analyses (CSAs) and Criticality Safety Specifications (CSSs) for the Richland Facility. Required design features are listed in the both the CSA and CSS. Operations personnel are required to review the CSSs on a quarterly basis. Each of these actions will reduce the likelihood of repeating this or simitas violations.
If you have questions regarding SPC's actions in response to this condition, please contact-me on 509-375-8537.
Very truly yours, J
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@Cy% NRM L J. Maas, Manager Regulatory Compliance LJM:pm i