DCL-05-108, Median Signal Select Software
| ML052770550 | |
| Person / Time | |
|---|---|
| Site: | Diablo Canyon  |
| Issue date: | 09/28/2005 |
| From: | Jacobs D Pacific Gas & Electric Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| DCL-05-108, OL-DPR-80, OL-DPR-82 | |
| Download: ML052770550 (3) | |
Text
Pacific Gas and Electric Company' Donna Jacobs Diablo Canyon Power Plant Vice President P. 0. Box 56 Nuclear Services Avila Beach, CA 93424 805.545.4600 September 28, 2005 Fax: 805.545.4234 PG&E Letter DCL-05-108 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Docket No. 50-275, OL-DPR-80 Docket No. 50-323, OL-DPR-82 Diablo Canyon Power Plant Units 1 and 2 Median Signal Select Software
Dear Commissioners and Staff:
In Pacific Gas and Electric Company (PG&E) Letter DCL-90-150, "Additional Information Regarding License Amendment Request 89 Median Signal Select Testing and Configuration Control," dated June 12, 1990, PG&E provided information to the NRC regarding control of the Digital Feedwater Control System Median Signal Select (MSS) software.
The MSS software, for each steam generator, selects the median of three water level instrument input signals. By selecting the median signal, a single random failure will not cause a control system action that results in a condition requiring protective action.
In DCL-90-150, PG&E stated the following:
"The configuration of the MSS will be controlled in several ways. First, the MSS function is subject to engineering design change control. Accordingly, any modifications to the MSS will be accomplished in accordance with the engineering design change program. The procedure for processing design changes is found in the Nuclear Engineering Manual, Procedure 3.6 ON,
'Operating Nuclear Plant Design Changes.' The procedure includes a requirement for conducting a safety evaluation to satisfy the requirements of 10 CFR 50.59. Configuration control of the software required for MSS operation is currently maintained by the system supplier. If PG&E should decide to assume configuration control responsibility for the MSS software, PG&E will notify the NRC."
A member of the STARS (Strategic Teaming and Resource Sharing) Altiance Callaway
- Comanche Peak
- Diablo Canyon
- Palo Verde
- South Texas Project
- Wolf Creek
Document Control Desk PG&E Letter DCL-05-108 September 28, 2005 Page 2 In the safety evaluation for License Amendment Nos. 56 and 55, for DCPP Units 1 and 2, respectively, the NRC stated the following:
"The licensee stated that reconfiguration of the MSS is not planned at the present time. However, for the first year of operation, any proposed configuration changes or modifications to the MSS will be submitted and reviewed by the system vendor, Westinghouse. Any FWCS modification after the first year of operation will be made through the issuance of a Diablo Canyon Design Change Procedure (DCP) in conformance with PG&E Engineering Procedure 3.6 ON, 'Operating Nuclear Plant Design Changes.'
This process may not involve Westinghouse but will be consistent with the original Westinghouse design. In addition, in its letter of June 12, 1990, the licensee committed to notify the NRC in the event that PG&E decides to assume configuration control responsibility for the MSS software (currently being maintained by Westinghouse). The staff finds the licensee's plan acceptable because it provides an adequate level of control of potential FWCS changes."
The purpose of this letter is to notify the NRC that PG&E is assuming configuration control responsibility for the MSS software.
Diablo Canyon Power Plant (DCPP) Procedure CF3.1D9, "Design Change Development," provides administrative controls over design changes, including software changes. DCPP Procedure CF2.1D9, "Software Quality Assurance Plan Software Development," provides administrative controls over in-house development of all new software applications. DCPP plant procedures require performing a licensing basis impact evaluation (LBIE) screen, in accordance with 10 CFR 50.59, to determine if a LBIE or prior NRC approval is required, before to making any changes to the MSS software. DCPP procedures will provide adequate controls over the MSS software.
If there are any questions regarding this change, please contact Mr. Stan Ketelsen at (805) 545-4720.
Sincerely, Donna Jobs Vice President - Nuclear Services A member of the STARS (Strategic Teaming and Resource Sharing) Alliance Carlaway
- Comanche Peak
- Diablo Canyon
- Palo Verde
- South Texas Project
- Wolf Creek
Document Control Desk September 28, 2005 Page 3 PG&E Letter DCL-05-108 mjrm/4557 cc:
Edgar Bailey, DHS Terry W. Jackson Bruce S. Mallett Girija S. Shukla Diablo Distribution A member of the STARS (Strategic Teaming and Resource Sharing) Alliance CalLaway
- Comanche Peak
- Diablo Canyon
- Palo Verde
- South Texas Project
- Wolf Creek