ML20248M039
| ML20248M039 | |
| Person / Time | |
|---|---|
| Site: | Paducah Gaseous Diffusion Plant |
| Issue date: | 06/08/1998 |
| From: | Polston S UNITED STATES ENRICHMENT CORP. (USEC) |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| 70-7001-98-06, 70-7001-98-6, NUDOCS 9806120282 | |
| Download: ML20248M039 (4) | |
Text
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. A Global Energy Company June 8,1998 GDP 98-1039 U. S. Nuclear Regulatory Commission Attention: Document Control Desk k ashington, D.C. 20555-0001 Paducah Gascors Diffusion Plant (PGDP)
Docket No. 70-7001 Response to Inspection Report (IR) 70-7001/98006 Notice of Violation (NOV)
The subject IR contained one NOV conceming the failure to verify by testing the adequacy of the Building C-720 criticality accident alarm system (CAAS) hom design under conditions that simulate the most adverse design requirements. USEC's response to the violation is provided in Enclosure
- 1. The corrective actions specified in the enclosures apply solely to PGDP. lists the commitment contained in this submittal. Any questions regarding this matter should be directed to Larry Jackson at (502) 441-6796.
Sincerely, a
/
Steve Polston General Manager Paducah Gaseous Diffusion Plant
Enclosures:
As Stated cci NRC Region ll! Office NRC Resident Inspector-PGDP i
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9006120282 990600 '
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PDR ADOCK 07007001
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. s. v.1 k P.O. Box 1410, Paducah, KY 42001 Telephone 502-441-5803 Fax 502-441-5801 http://www.usec.com Offices in Livermore, CA Paducah, KY Portsmouth, OH Washington, DC i
GDP 98-1039 Page1of3 l
UNITED STATES ENRICHMENT CORPORATION (USEC)
REPLY TO NOTICE OF VIOLATION (NOV) 70-7001/98006-01 l.
Restatement of the Violation i
Title 10 of the Code of Federal Regulations, Part 76.93, " Quality Assurance," requires, in part, that i he Corporation shall establish and execute a Quality Assurance Program.
t Item 3 of Section 2.3.3.4 of the Quality Assurance Program, " Design Verification," required, in part, that procedures for design verification activities shall be established and that design verification shall be completed prior to relying upon the component, system, structure, or computer program to -
. perform its function. Item 5 requires, in part, that verification by testing shall demonstrate adequacy
' of performance under conditions that simulate the most adverse design requirements.
Contrary to the above:
From March 3,1997 through April 6,1998, the Corporation failed to verify by testing the adequacy of the Building C-720 criticality accident alarm system horn design under conditions that simulate the most adverse design requirements prior to relying upon the system to perform its function of alerting personnel to an inadvertent criticality. Specifically, testing and quarterly surveillance tests conducted after the design was modified in March 1997 did not demonstrate that the 24-volt channel of the Building C-720 criticality accident alarm system would sound the building horns for the 120 seconds required by Technical Safety Requirement 2.6.4.1 upon loss of the 48-volt channel.
USEC Response I.1
~ Reason for the Violation The root'cause for this violation was an inadequate understanding of the C-720 criticality
' accident alarm system (CAAS) circuit design resulting in an inadequate Post-Maintenance Test (PMT).- As was noted in the Inspection Report, a modification was made to the CAAS hom circuitry on March 1,1997,in order to improve its response time. Plant personnel did not recognize that this modification might affect the capability of one of the two independent alarm circuits to sound the building horns until manually reset. (i.e., a design requirement).
As a result, the procedure used to test the CAAS circuitry following the modification (i.e.,
q CP4-GP-lM6178," Maintenance of the C-720 Criticality Accident Alarm System"), did not ensure that the alarm homs would sound for a minimum of 120 seconds using either of the two independent alarm circuits.- The ' inadequate understanding of the ' circuit design is considered an isolated case, in that review of the vendor's product documentation and related discussions with the vendor did not identify any concerns with the proposed modification.
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GDP 98-1039 Page 2 of 2 11.
Corrective Actions Taken and Results Achieved i
- 1. An additional modification of the circuitry was completed and the C-720 CAAS was satisfactorily tested by Maintenance on April 8,1998. This modification replaced a relay which had caused the horns to sound for only 10 seconds on the 24-volt circuit path.
- 2. The vendor technical manual was updated to include additional information on the alarm input channels for the C-720 CAAS Audible Alarm System. This information provided design information not previously available.
- 3. On May 21,1998, plant personnel verified that each of the two independent alarm circuits could independently maintain actuation of the CAAS horns for at least 120 seconds.
f III.
Corrective Action to Be Taken i
The lessons learned associated with this violation will be provided to appropriate design Engineering personnel by July 1,1998.
IV.
Date of Full Comnhance
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USEC achieved full compliance on May 21,1998, when it was verified that the system could independently maintain actuation of the C-720 CAAS horns for at least 120 seconds.
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GDP 98-1039 Page1ofI LIST OF COMMITMENTS 1.
The lessons learned associated with this violation will be provided to appropriate design Engineering personnel by July 1,' 1998.
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