ML092860144
| ML092860144 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 10/13/2009 |
| From: | Peter Bamford Plant Licensing Branch 1 |
| To: | Chernoff H Plant Licensing Branch 1 |
| Bamford, Peter J., NRR/DORL 415-2833 | |
| References | |
| Download: ML092860144 (5) | |
Text
October 13, 2009 MEMORANDUM TO: Harold K. Chernoff, Chief Plant Licensing Branch I-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation FROM:
Peter Bamford, Project Manager /RA/
Plant Licensing Branch I-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation
SUBJECT:
THREE MILE ISLAND, UNIT NO. 1 - ELECTRONIC TRANSMISSION, DRAFT REQUEST FOR ADDITIONAL INFORMATION REGARDING PROPOSED TECHNICAL SPECIFICATION CHANGES TO REFLECT CONTROL ROD DRIVE CONTROL SYSTEM REPLACEMENT The attached draft request for additional information (RAI) was transmitted by electronic transmission on October 9, 2009 to Mr. Frank Mascitelli, at Exelon Generation Company, LLC (Exelon, the licensee). This draft RAI was transmitted to facilitate the technical review being conducted by the Nuclear Regulatory Commission (NRC) staff and to support a conference call with Exelon in order to clarify the licensees amendment request regarding technical specification changes to reflect the planned replacement of the Control Rod Drive Control System. The draft RAI is related to the licensees submittal dated September 29, 2008, and supplements dated May 6, 2009, June 23, 2009, August 21, 2009, and September 17, 2009.
The draft questions were sent to ensure that they were understandable, the regulatory basis was clear, and to determine if the information was previously docketed. Additionally, review of the draft RAI would allow Exelon to evaluate and agree upon a schedule to respond to the RAI.
This memorandum and the attachment do not represent an NRC staff position.
Docket Nos. 50-289
Enclosure:
As stated
October 13, 2009 MEMORANDUM TO: Harold K. Chernoff, Chief Plant Licensing Branch I-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation FROM:
Peter Bamford, Project Manager /RA/
Plant Licensing Branch I-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation
SUBJECT:
THREE MILE ISLAND, UNIT NO. 1 - ELECTRONIC TRANSMISSION, DRAFT REQUEST FOR ADDITIONAL INFORMATION REGARDING PROPOSED TECHNICAL SPECIFICATION CHANGES TO REFLECT CONTROL ROD DRIVE CONTROL SYSTEM REPLACEMENT The attached draft request for additional information (RAI) was transmitted by electronic transmission on October 9, 2009 to Mr. Frank Mascitelli, at Exelon Generation Company, LLC (Exelon, the licensee). This draft RAI was transmitted to facilitate the technical review being conducted by the Nuclear Regulatory Commission (NRC) staff and to support a conference call with Exelon in order to clarify the licensees amendment request regarding technical specification changes to reflect the planned replacement of the Control Rod Drive Control System. The draft RAI is related to the licensees submittal dated September 29, 2008, and supplements dated May 6, 2009, June 23, 2009, August 21, 2009, and September 17, 2009.
The draft questions were sent to ensure that they were understandable, the regulatory basis was clear, and to determine if the information was previously docketed. Additionally, review of the draft RAI would allow Exelon to evaluate and agree upon a schedule to respond to the RAI.
This memorandum and the attachment do not represent an NRC staff position.
Docket Nos. 50-289
Enclosure:
As stated DISTRIBUTION:
Public RidsNrrPMPBamford LPL1-2 R/F Accession No.: ML09
- via email OFFICE LPL1-2/PM EICB NAME PBamford PLoeser for WKemper*
DATE 10/13/09 10/09/2009 OFFICIAL RECORD COPY
Enclosure REQUEST FOR ADDITIONAL INFORMATION THREE MILE ISLAND NUCLEAR STATION, UNIT 1 CONTROL ROD DRIVE CONTROL SYSTEM REPLACEMENT AND AXIAL POWER SHAPING ROD REMOVAL DOCKET NO. 50-289 By letter dated September 29, 2008 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML082800174, AmerGen Energy Company, LLC, the licensee1, submitted a license amendment request (LAR) for Three Mile Island Nuclear Station, Unit 1 (TMI-1). The LAR proposes to modify Technical Specifications (TSs) related to the Control Rod Drive Control System (CRDCS), Reactor Trip Breakers (RTBs) and Axial Power Shaping Rods (ASPRs). These proposed changes reflect a planned CRDCS upgrade to a digitally based system that will result in the replacement of the TMI-1 reactor trip breakers and elimination of the APSRs. On May 6, 2009 (ADAMS Accession No. ML091260765), and June 23, 2009 (ADAMS Accession No. ML091750846), the licensee provided supplemental information. Included in the May 6, 2009 submittal was information that the RTBs contain microcontrollers. On August 21, 2009 (ADAMS Accession No. ML092400175), the licensee provided supplemental information in response to a request for additional information concerning the microcontrollers. In order for the NRC staff to complete its review of the LAR, a response to the following request for additional information is requested.
- 1.
- a.
What is the microcontroller in the Schneider/Square D Masterpact NT breaker used for in this application?
- b.
Is the microcontroller in the Masterpact NT breaker used in a safety-related application? Include a discussion of the function of the shunt trip device.
- c.
How can failure of the microcontroller affect the safety-related application?
- d.
How was it determined that no software common cause failure would prevent the safety function?
1 The operating license for TMI-1 has been transferred from AmerGen Energy Company, LLC to Exelon Generation Company, LLC as of January 8, 2009.
- 2.
- a.
Please describe the components of the microcontroller in the Schneider/Square D Masterpact NT breaker.
- b.
Which microcontroller is used? Please provide the brand and model.
- c.
How does the microcontroller accomplish its function?
- d.
What safety function does the microcontroller perform? How does the microcontroller perform its safety function?
- e.
The staff notes that the Nuclear Logistics, Inc. (NLI) Verification and Validation (V&V) Report, VVR-042181-1, lists different part numbers for the Masterpact NT breaker undervoltage device and the shunt trip device. What are the differences in hardware and software in these two devices?
- 3.
- a.
Is the same firmware in both the undervoltage and shunt trip devices?
- b.
If so, how would a software common cause failure (CCF) impact the diverse trip of the two devices?
- c.
Does the undervoltage device have a safety-related low voltage function? If so, how would failure of the undervoltage device affect this function?
- 4.
Describe the analysis or testing that determined that there is no credible failure of the undervoltage device that would keep it energized.
- 5.
The licensees May 6, 2009 letter states that Failure of the microcontroller on the shunt trip device would have the same effect as coil failure, loss of power or blown fuse, which is similar to the existing designs failure modes. What is the basis for this statement?
- 6.
- a.
In Section 5.3 of the NLI V&V report it states, A highly controlled process was used to develop and test the software and software/hardware system. How was it determined that Schneider/Square D used a highly controlled process to develop and test the software and the software/hardware system?
- b.
What is the evidence of Schneider/Square Ds highly controlled process of software development?
- c.
How does this development process compare with the software development process required by NUREG 0800 Standard Review Plan Chapter 7, BTP 7-14?
- d.
Please provide documentation of this software development process.
- 7.
- a.
In Section 1.5 of the NLI V&V report, it states, There have been no revision to the trip unit software since it was issued in 1998. However, the licensees August 21, 2009 letter states, There have been no revisions to either the code or the hardware on the microcontrollers since the production release in 2002.
Please address the differences in these statements.
- b.
What is the history of software revisions prior to 2002?
- c.
What were the problems with the software prior to 2002?
- 8.
- a.
Discuss the worst case firmware CCF and its results.
- b.
Is the worst case firmware CCF bounded by the plant safety analysis?
- 9.
The September 29, 2008 LAR proposes the deletion of the word Indicator from Check with Relative Position Indicator, and Check with Absolute Position Indicator, the Remarks column in Table 4.1.1, Functions 23 and 24, respectively.
As part of the change in the control rod drive system the analog Control Rod Relative Position and Control Rod Absolute Position meters would be replaced by the Flat Panel Position Indication Display. The Flat Panel Position Indication Display would show Control Rod Zone Reference Switch Status and either Control Rod Relative Position or Control Rod Absolute Position. What would be the impact of replacing the word Indicator with the word Indication in the Remarks column for Functions 23 and 24, in lieu of deleting the word Indicator?