MTA-MA-029 - Revision history

Monica Hurley: Revision 0 Reviewed by Colton Smith

2026-03-26T17:23:51Z

Revision 0 Reviewed by Colton Smith

@@ Line 1: / Line 1: @@
 {{DISPLAYTITLE:Reduce Inspection Cost for Isophase Bus Duct Using Robotic Crawler - MTA-MA-029}}
 {{MTATemplate||
 | Date |12/14/2021
 | Functional Area Where Benefits Will Be Realized | Maintenance
 | Reference Implementation Guidance | Nuclear Maintenance Applications Center: Isolated Phase Bus Maintenance Guide (EPRI [https://www.epri.com/research/products/1015057 1015057])
-| Industry SME | EPRI – Sam Johnson
+| Industry SME | EPRI – NDE
 Contact: NuclearPlantMod@epri.com
 | Previous Implementation | This improvement has been implemented at several nuclear power plants. Please contact EPRI for implementation examples and contacts.
 | Implementation Enablers | N/A
 | Applicability | All Reactor Types
 All Geographic Regions
@@ Line 52: / Line 46: @@
 There is an additional risk of foreign material intrusion related to sending the crawler into the isophase bus duct, if the crawler were to be disabled or immovable. This risk can be mitigated through typical precautions and procedural controls for work in the isophase bus duct, including the establishment of a recovery plan in case the crawler gets tangled (if tethered) or stuck.

Jacob Sommer: 1 revision imported

2026-03-05T01:37:56Z

1 revision imported

← Older revision	Revision as of 01:37, 5 March 2026
(No difference)

10.142.237.162: /* Schedule */

2026-03-03T20:43:18Z

Schedule

New page

{{DISPLAYTITLE:Reduce Inspection Cost for Isophase Bus Duct Using Robotic Crawler - MTA-MA-029}}
{{MTATemplate||
| Date |12/14/2021
| Functional Area Where Benefits Will Be Realized | Maintenance
| Reference Implementation Guidance | Nuclear Maintenance Applications Center: Isolated Phase Bus Maintenance Guide (EPRI [https://www.epri.com/research/products/1015057 1015057])
| Industry SME | EPRI – Sam Johnson

Contact: NuclearPlantMod@epri.com
| Previous Implementation | This improvement has been implemented at several nuclear power plants. Please contact EPRI for implementation examples and contacts.
| Implementation Enablers | N/A
| SWEEP Score |
* Cost – Level 3 – Using a robotic crawler to inspect the isophase bus duct is expected to cost less than $1 million.
* Savings – Level 1 – Savings are expected to be less than $1 million per inspection.
* Payback – Level 3 – The payback period for vendor‑supported implementation is expected to be immediate. For in‑house implementation, the cost of the crawler is estimated to be recovered within one implementation.
* Technical Readiness – Level 3 – This technology has already been implemented at nuclear power plants.
* Licensing Readiness – Level 3 – The technology is commercially available and has already been used at commercial nuclear sites.
* Implementation Proficiency – Level 3 – The implementation of robotic crawlers has been performed by nuclear power plants in the past and does not require the utility to have specific knowledge.
| Applicability | All Reactor Types
All Geographic Regions
| Keywords | ROV examination; rover; remote visual inspection; non‑destructive examination; NDE; ducting; ventilation duct; electrical equipment; arcing; generator trip; plant scram; isophase bus system
| Business Case Analysis Cross-Reference | N/A
}}

==Description==
The isophase bus system in nuclear power plants transfers power between the generator and transformers, providing a critical function for power distribution. Failures of the system, although infrequent, can have significant consequences for the connected equipment and may result in a forced outage, at significant cost to the plant. Manual inspections of the isophase bus duct and supports are typically performed every ten years to look for signs of cracking, corrosion, dust, debris, and moisture. Traditional methods for inspection include building extensive scaffolding along the length of the duct to allow personnel to enter it using numerous inspection hatches. However, scaffolding is expensive and time‑consuming to build, certify, and disassemble, and manual inspections necessitate personnel exposure to industrial hazards (e.g., heights and confined spaces).

A small robotic crawler equipped with a high‑definition camera can be used in place of manual inspection to determine the condition of the isophase bus system for routine or emergent maintenance. The crawler’s camera records high‑quality visual inspection data, allowing for improved evaluation of duct condition against previous inspection data. Because of the crawler’s small size, it can be inserted through one access point and is able to inspect the entire length of the duct and navigate around supports. This reduces the need to build scaffolding to only those areas where corrective action is needed, which decreases inspection time and reduces inspection costs. Safety is also increased through this inspection method by limiting personnel exposure to industrial hazards. Furthermore, areas of the duct that are not accessible manually may be accessible using a crawler, given its increased mobility and smaller size.

==Benefits==
===Benefits Estimate===
Level 1 – Savings are typically less than $1 million per site per inspection relative to using traditional manual techniques. Implementation at one utility resulted in a tenfold decrease in cost relative to a single manual inspection (primarily due to reduction in scaffolding cost).

===Benefits Description===
* Reduction in cost to inspect and time to inspect (from days to hours).
* Increased industrial safety by limiting personnel exposure to hazardous conditions (e.g., high elevations and confined spaces).
* Increased data quality from using a high‑definition camera and added capability to store inspection data for trending.
* Increased coverage of the inspection area due to the small size and mobility of the crawler.
* Reduced risk of damage to ductwork from the reduced load required to be supported by the duct.

==Costs and Schedule==
===Cost===
Level 3 – Implementation cost is typically less than $1 million per site per inspection. The experience of one utility using a vendor (rather than buying their own crawler) was that the cost of using the crawler for this application was approximately $100,000 per implementation.

===Schedule===
Planning typically takes less than six months. Approximately less than one day to complete the inspection.

===Scope Context===
Per isophase bus duct inspection. Estimates are based on vendor‑supported implementation.

==Risks==
The use of a robotic crawler for performing the isophase bus duct inspection creates risk for schedule delays due to technical and/or tool‑related issues with the crawler that would not affect a manual inspection. The risk can be mitigated by proper maintenance and usage of the crawler and utilizing personnel who specialize in this technology (e.g., a vendor or a dedicated internal program).

There is an additional risk of foreign material intrusion related to sending the crawler into the isophase bus duct, if the crawler were to be disabled or immovable. This risk can be mitigated through typical precautions and procedural controls for work in the isophase bus duct, including the establishment of a recovery plan in case the crawler gets tangled (if tethered) or stuck.