Utilities mull MOX fuel volume, reliability, cost

How can NNSA meet demand?

By Dan Yurman, Contributing Reporter

blenderLast week AREVA and the Tennessee Valley Authority signed a letter of intent to begin discussing the possible future use of mixed oxide fuel in TVA’s four reactors in Alabama and Tennessee. NNSA’s $4.6 billion MOX fuel plant, which Shaw AREVA MOX Services LLC is building at the Energy Department’s Savannah River Site, is slated to produce the fuel. The letter of intent does not oblige TVA to use the MOX fuel.

AREVA and MOX Services also signed a “preliminary, nonexclusive” agreement designating AREVA as a marketing agent for the MOX fuel that is manufactured to use AREVA components and fuel designs, AREVA said in a statement last Friday.

Utilities Hesitant

But FCW understands that uncertainties cloud the future of the MOX fuel that the plant is to start producing in the U.S. in 2016. Along with TVA, two other nuclear utilities, Duke Energy in North Carolina and Energy Northwest in Richland, Wash., have revealed that they are thinking about using MOX in their reactors. But Duke and TVA have expressed concerns to FCW about whether the fuel will be reliably delivered during reactor outages, when it is most needed.

So far the DOE plan calls for Shaw AREVA MOX Fuel Services to offer the fuel for sale to utilities. But the MOX plant produces only a small fraction of what a full-scale MOX plant can turn out. That is why, according to an NNSA official, DOE must maintain a backup inventory of 160 tU of conventional fuel, in case not enough MOX fuel is ready when a customer calls for it.

In fact, FCW has learned from NNSA that DOE has not yet determined who in the MOX fuel supply chain would be accountable to pay for the backup fuel in the event of a fuel shortfall—NNSA, Shaw AREVA MOX Services, or the fuel fabrication plant (most likely AREVA’s facility in Richland, Wash.).

It stands to reason that until the government resolves these basic issues of reliable and accountable fuel supply, utilities will be leery of signing a contract.

Rita Sipe, a spokeswoman at Duke’s Catawba 1,100-MWe Pressurized Water Reactor in South Carolina, said up to 40% of the core, or 77 of the reactor’s 193 fuel assemblies, must be replaced during an outage. If the fuel does not arrive on time, the utility is stuck with a reactor that is not generating any revenue. “We are open to new proposals from [Shaw-AREVA],” Sipe said, “but right now we have no clear path to a new contract for MOX fuel.”

Sipe was quick to point out that Duke supports the MOX fuel program, but also noted that the fuel has to be at the reactor by a date certain the meet the outage schedule. Duke sets the delivery date in every fuel contract for fuel.

“We would expect the supplier to provide alternative fuel that would operate safely in this specific reactor if the MOX fuel was not available,” she said.

TVA Ponders Obligations

tva-logoTVA spokesman Terry Johnson told FCW that reliable fuel services would be part of the supply contract if the utility decides to use MOX fuel in any of the three 1,100 MW BWR reactors at Browns Ferry or the two 1,100 MW PWR reactors at the Sequoyah site. But in conversation with FCW, TVA appeared to be especially interested in the fuel cost compared to conventional fuel. TVA hopes MOX would be cheaper.

But Johnson said this would not be a deal killer, because the utility’s charter requires it to support national defense initiatives. Burning plutonium in civilian power generators is a key nonproliferation program, which is why TVA began evaluating the MOX option in the first place.

Johnson added that TVA has conducted public scoping meetings last August and is on track to have enough information to make a decision by 2012.

A source at TVA who declined to be identified told FCW that if the fuel is competitively priced, the utility could conceivably place orders for up to 80% of the output from the MOX plant. But that does not work out to be very much, as the plant will put out less fuel than its competition.

In 2008 AREVA’S Melox facility produced 126 tonnes of MOX fuel in 250 MOX assemblies. The plant serves more than 30 reactors worldwide.

The NNSA plant is slated to start hot operations in 2016. Over the first 13-15 years of operation the plant will produce 17 tonnes of MOX fuel assemblies for Pressurized Water Reactors. Another nine tonnes of surplus plutonium will be fed in after the initial batch runs out.

The initial NRC license is valid for 20 years. The plant was built to process 34 tonnes of surplus weapons-grade plutonium into MOX fuel. It now looks like it will get a second wind.

Mix of Issues in Northwest

“It’s no secret we plan to use MOX,” says Energy Northwest spokesman Michael Paoli. “We’ve been looking at MOX since the mid-1990s.”

The Department of Energy’s Pacific Northwest Laboratory will be working with Energy Northwest to help it evaluate its options for using MOX fuel. The engineers performing the evaluation think that up to 30% of the reactor’s 764 assemblies, or 229 Boiling Water Reactor fuel assemblies, can be replaced by MOX fuel.

“We have no plans to use MOX fuel until the evaluation is done,” Paoli said. “We need to assess it with regard to the unique characteristics of the Columbia reactor.”

Among the issues to be examined are technical risks, operational changes, licensing issues and fuel specifications. Energy Northwest and Shaw AREVA MOX Services will share the funding. The fuel needs to be competitively priced, too.

“We won’t use MOX fuel that costs more than what we’re paying now,” he said.

The Nitty-Gritty on MOX Fuel

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Production rate

An NNSA official told FCW that the relatively low rate of production of MOX fuel by the new facility is tied to three factors (1) the number of fuel designs specified by customers, (2) the availability of feed material at the plant, and (3) the fuel outage plans and fuel orders of customers, typically two years ahead of need.

There are two types of fuel assemblies – BWR and PWR. They have difference configurations, and a one-third change out of conventional for MOX fuel for each type involves a different number of fuel assemblies, and fuel material, for each reactor type.

NNSA declined to provide information on the mix of PWR and BWR fuel assemblies saying only that the 34 tonnes of weapons grade plutonium would result on an output of 1,700 PWR MOX fuel assemblies. Demand would be measured by the core replacement rates for each customer's reactor, though none would exceed 50% of the total number of fuel assemblies.

Fuel assembly manufacturing may take place at AREVA's plant in Richland, WA, which means the either the sintered fuel pellets, or the powder form of the two oxides, may have to be shipped from South Carolina to Washington. Another source, which asked to remain anonymous, told FCW that all fuel fabrication work for MOX fuel would take place at the South Carolina plant. An NNSA official declined to discuss technical details of the fuel fabrication process or where the work would be done.

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1 comments:

David said...

Good Article, but:
1. MOX is a mixture of either Natural U or depleted, not enriched. Would defeat the purpose.
2. Completed fuel assemblies will be delivered from SRS. Security implications of moving MOX pellets or blended powder would add interesting complications
3. When Melox started it was a 100 tonne a year plant, experience and process improved have allowed Areva to improve it's nameplate capacity with the approval of the French Regulator. Perhaps the same will hold true at SRS.
4. The idea of making up US capacity with imports from Frnace isn't a bad idea, except where would the PU come from. Melox is delivering MOX from Customer Pu recovered from reprocessing at La Hague. Also Rx grade Pu is different than Weapons stuff. So another licensing challenge.