Increase Safety and Reduce Rechannels Through the Use of Advanced Materials in BWR Fuel Channels - MTA-NF-003

Administrative Items
Date	12/15/2020
Functional Area Where Benefits Will Be Realized	Fuels
Reference Implementation Guidance	2016 NEI TIP Awards – Submittal 37 (ID: 9108725) NEDO-33798 Supplement 1, “NSF Channel Annual Experience Summary Report”
Industry SME	EPRI – Aylin Kucuk Contact: NuclearPlantMod@epri.com
Previous Implementation	Please contact EPRI for implementation examples and contacts.
Implementation Enablers	N/A
SWEEP Score	Cost – Level 3 – The cost of NSF fuel channels is similar to fuel channels made from Zircaloy. Costs related to engineering change package are expected to be less than $1 million. Savings – Level 1 – Savings depend on the number of channel replacements typically required and on generation lost when disabling of control blades is necessary. Based on 20 channel replacements per outage, the savings would be approximately $600,000 per outage or $300,000 per year. Payback – Level 2 – Based on the cost and savings information above, the payback period is between one and five years. Licensing Readiness – Level 3 – The NRC approved full reloads using NSF channels in 2016. Z4B channels were approved in batch quantities in 2019. Technology Readiness – Level 3 – This technology is in use at nuclear plants. Implementation Proficiency – Level 3 – The implementation of this technology does not require knowledge of digital technologies.
Applicability	BWRs All geographic regions (licensing readiness may vary by region)
Keywords	BWR; fuel; channel; rechanneling; control blade; interference; NSF; Z4B; ZIRLO; LTZ
Business Case Analysis Cross-Reference	N/A

Description

The fuel bundles of Boiling Water Reactors (BWRs) are enclosed in channels (typically made from Zircaloy). During operation, the channel walls are subject to radiation and corrosion, which may cause bowing. This deformation can reduce the size of the gap between a channel and a control blade and may eventually cause interference and associated sticking or blocking of the control blades. The affected control blades may have to be fully inserted into the core and disabled to reduce scram times. Replacement of channels (rechanneling) during outages may be required to restore the channel geometry. Channels made of advanced materials feature increased resistance to bowing, improve plant safety, and eliminate the need for costly and time‑consuming rechanneling. This MTA is based on operating experience with Global Nuclear Fuel’s (GNF) niobium, tin, iron (NSF) channels that were approved by the NRC in 2016. Similar benefits are expected from advanced materials offered by other vendors such as Framatome’s Z4B (approved in 2019) and Westinghouse’s Low‑Tin ZIRLO (LTZ, primarily used in Europe).

Benefits

Benefits Estimate

Level 1 – The cost of replacement and disposal of one deformed channel is approximately $30,000. By avoiding 20 channel replacements, savings of $600,000 per outage ($300,000 per year) can be realized. Additional savings may be realized by avoiding disabling of control blades and avoiding the associated reduction in capacity factor.

Benefits Description

• Elimination of need for rechanneling to avoid control blade interference.
• Increased capacity factors because disabling of control blades can be avoided.
• Reduction of reactivity maneuvers to test for channel bowing with associated reduction in risk of operator error, equipment challenges, etc.
• Extension of control blade life by reducing or eliminating the need for proactively inserting and disabling control blades in bowed channels.

Costs and Schedule

Cost

Level 3 – The cost of NSF fuel channels is similar to fuel channels made from Zircaloy. Costs related to developing an engineering change package are expected to be less than $1 million.

Schedule

One to three years

Scope Context

Per reactor

Risks

Limited experience with full reload quantities of NSF channels has been collected since full reloads using NSF channels were approved by the NRC in 2016. Results for full reloads that have undergone three complete cycles were not available at the time this MTA was written but will likely be reported later in 2020. Results from small batches indicate good performance.