ML23003A767
| ML23003A767 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 09/30/2022 |
| From: | Jeffrey Riley Dominion Energy Nuclear Connecticut |
| To: | Brian Fuller NRC/RGN-I/DORS/OB |
| References | |
| EPID L-2022-OLL-0007 | |
| Download: ML23003A767 (1) | |
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AOP 2580 Revision 003---06 Page 12 of 12 Millstone Unit 2 Degraded Voltage Level of Use Continuous STOP THINK ACT REVIEW 600 400 200 0
200 400 600 800 200 400 600 800 1000 A 60 psig A 45 psig A 30 psig A 15 psig D
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0.60 PF 0.70 PF 0.80 PF 0.85 PF 0.90 PF 0.95 PF 0.98 PF 0.95 PF 0.90 PF 0.80 PF 0.70 PF 0.60 PF 100 300 500 700 900 1100 0
CURVE AB IS LIMITED BY FIELD HEATING CURVE BC IS LIMITED BY ARMATURE HEATING CURVE CD IS LIMITED BY ARMATURE CORE END HEATING KILOWATTS x 1000 KILOVARS x 1000 LAG LEAD 0.90 PF, 0.50 SCR, 60 PSIG HYDROGEN PRESSURE, 500 VOLTS EXCITATION
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DOMINION ENERGY MA-AA-103 REVISION 18 PAGE 34 OF 50 Purpose provides an additional tool to measure risk and rigor impact during specific troubleshooting activities and is intended for use during plan development. The information contained in Attachment 1 is based on industry experience and is intended to provide a mental model for the TTL during action step development. This attachment is not designed to replace or alter any risk assessment through PRA. The TTL can use this reference to provide a level of risk and rigor to support minimizing the impact to plant systems and equipment.
Notes 1.
These are strictly guidelines and cannot capture every troubleshooting activity. The TTL and team will have to exercise judgment to ensure a conservative decision is made during the troubleshooting approval.
2.
It is acceptable to invoke a different level of rigor based on the plant conditions and other factors.
3.
Particular attention is required when the troubleshooting has the potential to impact the design function and/or operational status of any structures, systems, or components that are being relied upon to support plant operation or achieve and maintain safe shutdown.
Steps for use of Attachment 1:
1.
Review troubleshooting scope against guidelines on page 2 to determine troubleshooting risk level.
2.
Review activity matrix on page 3 to determine the rigor category if the troubleshooting steps fall within examples provided or similar actions.
3.
If applicable, utilize the category list on page 4 to include the level of rigor in the plan details and involvement of the personnel to minimize the risk to plant systems and personnel.
ATTACHMENT 1 (Page 1 of 4)
Risk and Rigor Determination Matrix
DOMINION ENERGY MA-AA-103 REVISION 18 PAGE 35 OF 50 Guidelines for Level of RISK Determination I. HIGH RISK:
Equipment is not removed from service. Presents a risk of tripping the plant, actuating a safety system, causing a significant reactivity change, or possible radiation release, either directly or as a result of causing a major plant transient.
II. MEDIUM RISK:
Equipment is not removed from service. Could result in an undesirable plant transient, affect reactivity, or a reportable event, but not a reactor trip or safety system activation.
III. LOW RISK:
Equipment is not removed from service. Could have an affect on plant equipment, but should not present a risk of causing an undesirable plant transient, reactivity change, or reportable event. No unusual personnel safety risk.
IV. NO RISK:
Equipment is removed from service. Troubleshooting activities do not affect the operation or safety of the plant.
EXAMPLE: Removing an instrument loop from service in a high-Risk classification was classified as a Category A activity. Once the loop is out of service and the device is in the shop, it can be moved to a lower risk classification. At this time the changes to the plan affecting the shop activity could be performed IAW the lesser requirements of the above table.
ATTACHMENT 1 (Page 2 of 4)
Risk and Rigor Determination Matrix
DOMINION ENERGY MA-AA-103 REVISION 18 PAGE 36 OF 50 Activity Rigor Category I-High Risk II-Medium Risk III-Low Risk IV-No Risk Diagnostic hookup with signal injection on equipment in service which is not performing its intended function without approved procedures.
A B
C N/A Diagnostic hookup with signal injection on equipment in service which is performing its intended function without approved procedures.
A A
B N/A Diagnostic hookup for monitoring on equipment in service without test points.
A A
C N/A Diagnostic hookup for monitoring on equipment in service with test points.
C C
C N/A Removal from service without approved procedures.
A A
C N/A Return to service without approved procedures.
A A
C N/A Voltage/current readings on in service equipment without test points.
A A
C N/A Voltage/current readings on in service equipment with test points.
C C
C D
Pressure/temperature/level changes without approved procedures.
A B
C N/A Energized equipment that is out of service without approved procedures.
C C
C C
Visual inspection with barrier intrusion.
C C
D D
Visual inspection with no barrier intrusion.
D D
D D
Current readings on in-service equipment using a clamp-on device.
C D
D N/A ATTACHMENT 1 (Page 3 of 4)
Risk and Rigor Determination Matrix
DOMINION ENERGY MA-AA-103 REVISION 18 PAGE 37 OF 50 Guidelines for Level of RIGOR Determination Category A (Highest degree of rigor; tightest controls) 1.
Requires a troubleshooting plan with careful attention to risks to plant personnel and plant operation.
The troubleshooting plan may be initial or focused depending on the complexity of the issue.
2.
Determine the level of plant management (point of contact) that will be required to approve plan changes.
3.
If unexpected results are noted during the process of troubleshooting, notify point of contact and determine if the original plan is acceptable or should the plan be revised.
4.
If the troubleshooting results in expanded scope of equipment that was not previously considered, the plan requires revision and re-approval through the point of contact. (i.e., The problem was not the transmitter but is suspected to be a multiple end device power supply).
5.
SRO/management observer recommended being present during troubleshooting activities.
6.
Control Room briefing is required.
7.
Determine communication requirement with site leadership.
Category B 1.
Same as A1.
2.
Same as A2.
3.
Same as A4.
4.
Same as A5.
5.
Same as A6.
6.
Same as A7.
Category C Typically requires a simple troubleshooting plan.
Category D 1.
Typically requires a simple troubleshooting plan.
2.
May be performed with very little structured detail.
ATTACHMENT 1 (Page 4 of 4)
Risk and Rigor Determination Matrix