An OK to increase the output of Grand Gulf Nuclear Station — making it the single most powerful reactor in America — was approved Monday by the Mississippi Public Service Commission.

Proposed by Entergy in May, the power-up also requires federal approval.

If obtained, the “uprate” at the Claiborne County plant will be completed during a planned spring 2012 refueling and maintenance shutdown at a cost of $510 million.

PSC Chairman Lynn Posey said the approval came after the Public Utilities Staff drew up an order allowing the utility’s plans to proceed.

Grand Gulf’s capacity would rise to 1,443 megawatts from 1,265 — higher than the most productive reactor at Arizona’s Palo Verde plant by about 9 percent. It would be Grand Gulf’s second upgrade since 2002, when capacity was boosted by about 2 percent. Palo Verde’s three reactors generate the most of any plant in the United States overall, at more than 4,000 megawatts.

Virden Jones of the Public Utilities Staff said documents indicate minimal effect on ratepayers. The average customer will see added costs starting in 2013 that will continue for two years before savings are realized. The estimates are $5.82 more in 2013, $2.88 more in 2014, then savings of 96 cents in 2015 and $5.12 by 2017.

Grand Gulf, initially powered up in 1985 after an 11-year construction period, uses a controlled nuclear reaction to generate heat to boil water. The resulting steam is piped under pressure to a turbine, which spins to generate electricity that goes onto a grid with power from other plants. The uprate intensifies the process — more steam through a faster, more efficient generator.

In October, project managers and others from Entergy Mississippi told the three-member commission the costs of the upgrade were measured against an alternative plan to build a combined cycle gas turbine. Per-kilowatt hour costs for ratepayers of an upgraded Grand Gulf would equal 6.8 cents, termed a “marginal cost” in PSC’s order, while a turbine would cost 11.27 cents.

Monday’s PSC order states. “This (lower cost) benefit is in addition to the greater price certainty and stability from adding the Grand Gulf to the system’s generation portfolio.”

Other Entergy plants are gas-fired and for two years have experienced gyrating fuel costs.

The costs and benefits of the uprate are expected to effect all Entergy’s subsidiaries in Mississippi, Louisiana, Arkansas and one for New Orleans, according to the PSC order. Customers of South Mississippi Electric Power Association, which owns 10 percent of the plant and receives 10 percent of the energy, will see a $1.4 million savings starting in 2013 based on greater price certainty and adding the upgrade to the Hattiesburg-based utility’s generation portfolio, according to the order.

A ruling Nov. 19 by the Federal Energy Regulatory Commission allowing Arkansas and Mississippi to leave a capacity-sharing agreement by 2013 and 2015, respectively, was not addressed.

Increases in thermal operating limits, or the amount of steam needed to produce the higher capacity, must be approved by the Nuclear Regulatory Commission. Pending that action and another by the Federal Energy Regulatory Commission on the Large Generator Interconnection Agreement, the phased installation will be completed during a 45- to 80-day spring 2012 refueling outage. 

Though some full-time positions at the plant are listed due to the upgrade, most jobs created by the upgrade will be temporary, with up to 1,000 extra jobs expected six months after the first design phase starts, Entergy Nuclear spokesman Suzanne Anderson said.

“They will be in engineering, technical, construction, everything,” Anderson said.

The formal request to increase the plant’s generating capacity was made by System Energy Resources Inc., of which Entergy Corp. owns all common stock and has 90 percent ownership and leasehold interest in Grand Gulf, and by South Mississippi EPA, which owns 10 percent of the plant and receives 10 percent of energy produced by the plant. Customers of SMEPA will save $1.4 million annually as a result of the upgrade.  

A separate effort to license a second reactor at Grand Gulf and at Entergy’s River Bend Station in St. Francisville, La. remains alive on paper, but increasingly unlikely to proceed anytime soon due to economic factors. Chief among them, company officials have said, was a trip-ling of design plans to build the core of a second reactor.

GE-Hitachi, which had been in talks with the company to build the main component of a second reactor, was chosen for the design study on the uprate, according to the formal petition, while Siemens Power Corp. was selected to construct a new high-pressure turbine motor. Baton Rouge-based The Shaw Group was chosen prime contractor and labor supplier for the major modifications after a competitive bid, Entergy experts told the commission in October.

The Public Service Commission is composed of members elected from North, South and Central state districts and has oversight of private utilities ranging from small water districts to giants such as Entergy. A separate Public Utilities Staff receives data from utilities and conducts research on needs and costs.

*

Contact Danny Barrett Jr. at dbarrett@vicksburgpost.com