The Nuclear Power Thread

[Astronuc]

Accident tolerant fuel cladding development: Promise, status, and challenges (2017)​

https://www.osti.gov/biblio/1471930

The motivation for transitioning away from zirconium-based fuel cladding in light water reactors to significantly more oxidation-resistant materials, thereby enhancing safety margins during severe accidents, is laid out. A review of the development status for three accident tolerant fuel cladding technologies, namely coated zirconium-based cladding, ferritic alumina-forming alloy cladding, and silicon carbide fiber–reinforced silicon carbide matrix composite cladding, is offered. Technical challenges and data gaps for each of these cladding technologies are highlighted. Full development towards commercial deployment of these technologies is identified as a high priority for the nuclear industry.

It's a reasonable overview. It's a bit short on the interaction of fission products and claddings though, and how to deal with the high burnup structure (rim), which develops at/near the circumferential surface of the fuel pellets. Lots of challenges with coolant-cladding and fuel-cladding chemical interactions.

 

[Astronuc]

Constellation is discussing the possible retart of Three Mile Island with the State of Pennsylvania
https://www.reuters.com/business/en...e-mile-island-restart-sources-say-2024-07-02/

I expect that would be Unit 1 (TMI-1) at Three Mile Island. Unit 2 is the one that had the accident in 1979.

NEW YORK/PHILADELPHIA, July 2 (Reuters) - Constellation Energy (CEG.O)
, opens new tab is in talks with the Pennsylvania governor's office and state lawmakers to help fund a possible restart of part of its Three Mile Island power facility, the site of a nuclear meltdown in the 1970s, three sources familiar with the discussions said on Tuesday.

The conversations, which two sources described as "beyond preliminary," signal that Constellation is advancing plans to revive part of the southern Pennsylvania nuclear generation site, which operated from 1974 to 2019. The nuclear unit Constellation is considering restarting is separate from the one that melted down.

The sources said that a shut Michigan nuclear plant, which was recently awarded a $1.5 billion conditional loan to restart from the administration of U.S. President Joe Biden, could serve as a private-public sector blueprint for Three Mile Island.

 

[gmax137]

I wish them (and Palisades) luck, but I don't see how they can get a new operating license without making all of the changes they avoided over the years via the "backfit rule."

Just to pick one example, how could these units achieve cold shutdown (given a single failure and a loss of offsite power) using only safety-grade equipment operated from the control room? (NUREG-0800, BTP 5-4, the rule formerly known as RSB BTP 9-1). Units licensed before 1978 kind of skated on this, does the "re-license" also skate?

 

[Astronuc]

Just to pick one example, how could these units achieve cold shutdown (given a single failure and a loss of offsite power) using only safety-grade equipment operated from the control room? (NUREG-0800, BTP 5-4, the rule formerly known as RSB BTP 9-1). Units licensed before 1978 kind of skated on this, does the "re-license" also skate?

For background - https://www.nrc.gov/about-nrc/regulatory/crgr/related-info.html
https://www.nrc.gov/reading-rm/doc-collections/cfr/part050/part050-0109.html


I don't remember what backfitting/retrofitting and upgrades were employed at TMI-1, the more mature sibling unit of TMI-2, which suffered the accident.

May 16, 2024 - Could TMI be restarted? Someone asked, and the owner didn’t say no​

https://www.pennlive.com/news/2024/...omeone-asked-and-owner-said-didnt-say-no.html

I'd have to ask my contacts at Constellation.

I did some consulting with TMI-1 about 30 years ago when it was operated by GPUN (General Public Utilities - Nuclear, Inc). GPU Nuclear, Inc. (GPUN) was a New Jersey corporation and a wholly-owned subsidiary of GPU. GPUN was organized for the purpose of the safe operation, maintenance, rehabilitation, design, construction, start-up and testing of all nuclear generating facilities owned by JCP&L, Met-Ed and Penelec (collectively, the "GPU Operating Companies") and related research and development.

Unit 2 received its operating license on February 8, 1978, and began commercial operation on December 30, 1978. Some testing had occurred. On March 28, 1979, a cooling system malfunction caused a partial meltdown of the reactor core. {Ref: Wikipedia) The unit was in its first cycle of operation, and as I recall, had achieved 62 EFPD, so not a lot of decay heat, but enough to partially degrade the core when cooling/flow was lost. It would have been a lot worse had the unit been operating high burnup fuel (BU > 45 GWd/tU). That was high burnup when I was in grad school; I consider high burnup > 60 GWd/tU.

 

[gmax137]

I found this: INSPECTION MANUAL CHAPTER 2562 (Effective Date: 05/08/2024)
LIGHT-WATER REACTOR INSPECTION PROGRAM FOR RESTART OF REACTOR FACILITIES FOLLOWING PERMANENT CESSATION OF POWER OPERATIONS
https://www.nrc.gov/docs/ML2403/ML24033A299.pdf

But it doesn't answer my questions. I will continue to dig a little.

 

[Astronuc]

16 locations identified to expand Nebraska nuclear footprint, shortlist soon to be narrowed
https://nebraskaexaminer.com/briefs...lear-footprint-shortlist-soon-to-be-narrowed/

LINCOLN — The Nebraska Public Power District has identified 16 possible locations that could be candidates to expand Nebraska’s nuclear footprint and energy capabilities.

The Nebraska Department of Economic Development along with NPPD announced Thursday the next phase of a feasibility study that will eventually narrow down its shortlist to two to four sites for emerging nuclear technology: small modular reactors, or SMRs.

Compared to NPPD’s Cooper Nuclear Station near Brownville, SMRs take up less physical space and have been championed as augmenting existing power sources.

The 16 sites that will move on to the next phase of the feasibility study are located near the following cities: Beatrice, Brownville, Fremont, Grand Island, Hallam, Hastings, Holdrege, Kearney, Lexington, Nebraska City, Norfolk, Plattsmouth, Rushville, Sutherland, Valentine and Wauneta.

“We’re excited to help lay the groundwork for the potential future of this technology in Nebraska,” Department of Economic Development Director K.C. Belitz said in a statement. “Electrical generation is key to growing Nebraska’s economy and this study is the first step in creating a tremendous economic impact for any community where it’s located.”

The Legislature first appropriated $1 million of federal funds through the American Rescue Plan Act for the study in 2022 seeking to identify appropriate places to expand nuclear power.

Nebraska lawmakers explore feasibility of small modular nuclear reactors
https://nebraskaexaminer.com/2023/1...easibility-of-small-modular-nuclear-reactors/

Cooper Nuclear Station is a boiling water reactor type nuclear power plant located on a 1,251-acre site near Brownville, Nebraska between Missouri River mile markers 532.9 and 532.5, on Nebraska's border with Missouri. It is the largest single-unit electrical generator in Nebraska.

As I recall, the Cooper (GE BWR/4) unit produces 2419 MWth with a rate generation capacity of 835 MW. The net generation would be something like 800 MWe. The core contains 548 fuel assemblies.
https://www.nppd.com/powering-nebraska/energy-resources/nuclear

Cooper Nuclear Station celebrates 50 years of reliability
https://www.nppd.com/press-releases/cooper-nuclear-station-celebrates-50-years-of-reliability
Columbus, Neb. – Nebraska Public Power District’s (NPPD) Cooper Nuclear Station is celebrating 50 years of generating reliable energy for Nebraska, since first coming on-line July 1, 1974.

As I recall, it is the oldest BWR/4 in the US currently operating.

Back in 2022, Nebraska Public Power District and Entergy agreed to terminate their nearly 20-year-old support services agreement for the Cooper nuclear power plant. At that time, NPPD said that it intended to continue operating the plant—Nebraska’s sole power-generating nuclear facility—and will use Entergy and other available industry resources, as appropriate.
https://www.ans.org/news/article-3764/nppd-and-entergy-end-cooper-partnership/

Millstone 1 was the oldest BWR/4, which began commercial operation in 1970, but was shutdown prematurely in 1998.
https://en.wikipedia.org/wiki/Millstone_Nuclear_Power_Plant#Unit_1
https://en.wikipedia.org/wiki/GE_BWR#BWR-4 (article is somewhat out of date; it needs additional sources).
GE/GEH/GNF fuel bundles are well beyond GE9 (8x8). The last 8x8 bundle was GE10, which was for the BWR/6 plants. It was followed by GE11 and GE13 bundles with a 9x9 lattice, and GE12 and GE14 assemblies which were 10x10 lattices. The 10x10 lattices quickly replaced the 9x9 lattices, and GE14 became the standard for a while. GE formed a fuel manufacturing subsidiary, Global Nuclear Fuel, in partnership with Hitachi and Toshiba, but then Toshiba bought Westinghouse, and GE and Hitachi formed their partnership GEH, with fuel manufactured by GNF. At the same time, GNF introduced the GNF2, then GNF3 bundles, which are the current standard fuel designs. With GE creating GE Vernova, GEH overseas the nuclear fuel infrastructure.
https://www.gevernova.com/nuclear/fuels

https://www.gevernova.com/nuclear/fuels/gnf3
https://www.revistanuclear.es/wp-content/uploads/hemeroteca/361/NE361-02.pdf

And sometimes, things don't go as planned or intended.
https://www.nrc.gov/docs/ML2233/ML22334A267.pdf

Meanwhile, Westinghouse produces first batch of LEU+ fuel pellets

Westinghouse Electric Company announced Aug. 8 that it has completed the first pressing of ADOPT nuclear fuel pellets at the company’s Springfields Fuel Manufacturing Facility in the United Kingdom. The pellets, which can contain up to 8 percent uranium-235 by weight, are destined for irradiation testing in Southern Nuclear’s Vogtle-2 pressurized water reactor.

Enrichment bump up: Low-enriched uranium enriched up to 8 percent fits under no fewer than three labels: LEU, LEU+ (a term recently popularized by enrichment companies and nuclear technology developers for uranium enrichments between 5 and 10 percent U-235), and HALEU, or high-assay low-enriched uranium, which is defined as all uranium enrichment levels between 5 and 20 percent U-235.

 

[Astronuc]

Delays and cost overruns resulted in a major project cancellation last year

Last November, the Utah Associated Municipal Power System (UAMPS) terminated its agreement with NuScale for its Carbon Free Power Project. The agreement, initially made in 2015, would have involved the construction of 12 reactor modules to generate up to 600 MW, which would have been up and running by 2023.

The termination showed how expensive it could be to get the technology off the ground. Originally, the project's costs were estimated to be around $3 billion. These estimates rose to $6.1 billion in 2023 and $9.3 billion in 2023, finally becoming too expensive for UAMPS. As a result, NuScale's first planned operational SMR plant went up in smoke, and it had to take a $50 million charge.

https://finance.yahoo.com/news/nuscale-power-millionaire-maker-094500366.html

NuScale is currently the only company to receive a Standard Design Approval (SDA) from the Nuclear Regulatory Commission. However, one thing to keep in mind is that this is for its 50 MWe modular reactors, not its current 77 MWe reactors. NuScale had to upsize its original design because the economics of its previous 50 MWe reactors didn't work.

The company has requested an SDA from the commission for its 77 MWe reactors and expects this version to be approved by July 2025. However, this isn't a full certification, and it is projected to take another couple of years after that, which means full commercialization is still years away.

The 77 MWe SMR is named VOYGR. Plants are designed for 12 (924 MWe), 6 (~452 MWe) or 4 (~308 MWe) modules. Each module has a rated thermal power of 250 MWt (or roughly an efficiency of 0.308, excluding power diverted to operate the plant).
https://www.nuscalepower.com/en/products/voygr-smr-plants

The VOYGR core is comprised of 37 fuel assemblies of 17 x 17 pin array.
https://www.nuscalepower.com/-/media/nuscale/pdf/fact-sheets/smr-fact-sheet.pdf

Disclaimer: For information only. No endorsement expressed or implied.

 

[Astronuc]

Onagaw 2 (BWR) restarts! This is a big deal because it's a BWR. The unit is a more modern BWR-5 with capacities 2436 MWt, 825 MWe gross, 796 MWe net. The difference between gross and net is the electrical power used by the plant, about 29 MWe.

https://apnews.com/article/japan-nu...uake-restart-bf5b1e807822426386222d42b368fe17

The No. 2 reactor at the Onagawa nuclear power plant on Japan’s northern coast was put back online and is expected to start generating power in early November, operator Tohoku Electric Power Co. said.

The reactor is one of the three at the Onagawa plant, which is 100 kilometers (62 miles) north of the Fukushima Daiichi plant where three reactors melted following a magnitude 9.0 earthquake and tsunami in March 2011, releasing large amounts of radiation.

The Onagawa plant was hit by a 13-meter (42-foot) tsunami but was able to keep its crucial cooling systems functioning in all three reactors and achieve their safe shutdowns.

https://en.wikipedia.org/wiki/Onagawa_Nuclear_Power_Plant

https://www3.nhk.or.jp/nhkworld/en/news/20241029_04/

Fuel loading happened in September this year
https://world-nuclear-news.org/articles/fuel-loading-begins-ahead-of-onagawa-2-restart
https://www.neimagazine.com/news/onagawa-2-begins-fuel-loading/

https://world-nuclear.org/information-library/country-profiles/countries-g-n/japan-nuclear-power

IAEA-2012
ORIGINAL: English
IAEA MISSION TO ONAGAWA NUCLEAR POWER STATION TO EXAMINE THE PERFORMANCE OF
SYSTEMS, STRUCTURES AND COMPONENTS FOLLOWING THE GREAT EAST JAPANESE
EARTHQUAKE AND TSUNAMI
https://www.iaea.org/sites/default/files/iaeamissiononagawa.pdf

 

[Astronuc]

Japanese nuclear reactor (Onagawa Unit 2) that restarted 13 years after Fukushima disaster is shut down again
https://apnews.com/article/japan-nuclear-onagawa-reactor-bf8230471ede50e5f42767ae7cb31ce2

The No. 2 reactor at the Onagawa nuclear power plant on Japan’s northern coast was put back online on Oct. 29 and had been expected to start generating power in early November.

But it had to be shut down again five days after its restart due to a glitch that occurred Sunday in a device related to neutron data inside the reactor, plant operator Tohoku Electric Power Co. said.

The reactor was operating normally and there was no release of radiation into the environment, Tohoku Electric said. The utility said it decided to shut it down to re-examine equipment to address residents’ safety concerns. No new date for a restart was given.

The neutron data comes from different local power range monitoring detectors, which feed data to computers that offer a map of the core power and distribution in the reactor. An online core simulator provides a 3D map of the power distribution in the core, and thermocouples provide some indication of the coolant temperature.

https://www.nrc.gov/docs/ML1125/ML11258A333.pdf

In some cases, BWRs may have traversing in-core probes that move vertically in the core, which allows the operator to capture the local power as a function of axial position, which helps confirm the power distribution.
https://www.nrc.gov/docs/ML1125/ML11258A339.pdf

 

[Astronuc]

One of the challenges to new startup nuclear technology companies is financing and time.
Wednesday, 30 October 2024
Ultra Safe Nuclear Corporation files Chapter 11 petition
https://world-nuclear-news.org/articles/ultra-safe-nuclear-corporation-files-chapter-11-petition

USNC has achieved some manufacturing and testing of components.

The "most significant investor" for the company had been board chairman Richard Hollis Helms, whose family invested about USD100 million and loaned USD24.6 million. He died in May and "since then, the Debtors have continued to search for new capital sources to continue funding their research and development efforts pending the full launch of their products and projects".

USNC's MMR is a 45 MW thermal, 15 MW electrical high-temperature gas-cooled reactor, using TRISO fuel in prismatic graphite blocks. The graphite blocks contain stacks of ceramic FCM fuel pellets. The helium-cooled reactor can be flexibly fuelled with uranium enrichments from 9% to 19.75% and will have an initial licensed nuclear plant lifetime of 40 years. The company is currently working on deployment projects at Canadian Nuclear Laboratories' Chalk River site in Ontario, Canada, and at the University of Illinois Urbana-Champaign in the USA.

TRISO (from tristructural-isotropic) fuel particles contain spheres of uranium oxycarbide (or uranium dioxide) coated with ceramic layers that contain fission products inside the particle and ensure its mechanical and chemical stability during irradiation and temperature changes. The US Department of Energy has described TRISO as the most robust nuclear fuel on Earth. Framatome and USNC agreed on a joint venture last year with the goal of manufacturing TRISO particles and FCM fuel in late 2025.

 

[Astronuc]

Summary Status of US Nuclear Plants
https://www.eia.gov/nuclear/spent_fuel/ussnftab2.php (shutdown and decommissioned units included).

 

[Astronuc]

March 2023 - China begins operation of CGN's first Hualong One Nuclear Power Unit

The first Hualong One unit, a 1,180-MWe nuclear reactor designed by China General Nuclear (CGN), is now operational at the company’s Guangxi Fangchenggang Nuclear Power Station in western China’s Guangxi Autonomous Region.

Fangchenggang Nuclear Power Plant is 39% owned by Guangxi Investment Group and 61% by CGN. The plant plans to house six 1,000-MWe reactors, including two CPR-1000 units, which went online in 2016. Fangchenggang 3, which began commercial operation on March 25, and Fangchenggang 4 are part of the plant’s “second phase” to build out CGN’s first fleet of Hualong One reactors.

Hualong One, sometimes referred to as the HPR 1000, is considered China’s primary export reactor. The design derives from the ACP-1000, which was developed by the China National Nuclear Corp. (CNNC) and CGN’s ACPR-1000. China’s National Energy Administration in 2011 ordered competitors CNNC and CGN to merge their two third-generation reactor designs into one standardized design. Both the ACP-1000 and ACPR-1000 are three-loop pressurized water reactor (PWR) designs based on the French M310.

https://www.powermag.com/china-begins-operation-of-first-cgn-hualong-one-nuclear-reactor/

 

[Astronuc]

Framatome's ATF reaches new operational milestone
https://www.world-nuclear-news.org/articles/framatomes-atf-reaches-new-operational-milestone
The image in the article shows a 17x17 fuel assembly. Gösgen uses 15x15 fuel and is one of the most aggressive plants in terms of coolant temperature and heat flux (fuel duty).

Framatome's PROtect Enhanced Accident Tolerant Fuel chromium-coated M5Framatome cladding has become the world's first ATF technology to operate with full length fuel rods at a burnup rate above 60 GWd/tU.

Framatome's PROtect technology incorporates chromium-coated cladding, which significantly enhances oxidation resistance, improves mechanical performance at high temperatures, and reduces hydrogen generation in the unlikely event of a loss of cooling.

Fuel rods utilising Framatome's Enhanced Accident Tolerant Fuel E-ATF technology completed four 12-month cycles of operation at the Gösgen nuclear power plant in Switzerland earlier this year. The lead fuel rods consist of Framatome's advanced chromium coating added to the state-of-the-art M5Framatome zirconium alloy cladding, with uranium dioxide (UO₂) fuel pellets for some and with UO₂ chromia-enhanced fuel pellets for the others. The fuel assembly was fabricated at Framatome's fabrication facility in Lingen, Germany.

Visual examinations as well as dimensional changes measurement examinations (typically length to plot growth, and possibly profilometry for diametral changes), which are standard poolside examinations, were carried out during the plant's scheduled refuelling and maintenance outage in the spring.

The twelve lead fuel rods have been placed in their 5th cycle of operation. I would expect some or all the fuel rods will be sent to hot cell for both non-destructive and destructive testing.

Modern (UO₂) fuel pellets are doped with chromia or chromia-alumina to increase grain size for greater fission gas retention.

 

[Astronuc]

The first-of-a-kind VVER-TOI reactor, being built at Kursk II in Russia, uses the same engineering approaches as earlier VVERs, but has a few unique features

https://www.neimagazine.com/advanced-reactorsfusion/vver-toi-the-latest-evolution-9261505/?cf-view

The VVER-TOI design provides for a longer self-sustained emergency operation of a plant, as well as a smaller amount of solid radioactive waste and emissions. It combines active and passive safety systems. In addition, it ensures the transition of the reactor plant to a safe state in the event of various combinations of natural and man-made events causing a complete black-out: the power unit can survive a commercial aircraft crash, an earthquake and a tsunami happening simultaneously. The plant grace period requiring no operator intervention has been extended to 72 hours.

Since the VVER-TOI design uses the same engineering approaches as its predecessor, it requires no changes in the basic conceptual, structural and layout solutions for the power plant, though a new equipment layout is required. The steam generators are arranged in two rows, with two steam generators in a row. Earlier designs required a tangential arrangement around the nuclear reactor.

 

[gmax137]

I found this, a pretty good description of the design:
https://www.rosatom.ru/upload/iblock/0be/0be1220af25741375138ecd1afb18743.pdf

 

[Astronuc]

World Nuclear News articles on Small Modular Reactors (SMRs)
https://www.world-nuclear-news.org/TagSection?tagid=894

The Czech Republic's ČEZ and UK-based Rolls-Royce SMR have signed an Early Works Agreement to start site-specific work for potential small modular reactors at the Temelin nuclear power plant.
https://www.world-nuclear-news.org/...-royce-smr-sign-temelin-early-works-agreement

Oklo selects constructor for first Aurora powerhouse​

https://www.world-nuclear-news.org/articles/oklo-selects-constructor-for-first-aurora-powerhouse

Kairos Power installs third test unit reactor vessel​

https://www.world-nuclear-news.org/articles/kairos-power-installs-third-test-unit-reactor-vessel

The US Nuclear Regulatory Commission has accepted for review the construction permit application from Tennessee Valley Authority for a BWRX-300 small modular reactor at the Clinch River site in Tennessee. The regulator said it expects to complete its review within 17 months.
https://www.world-nuclear-news.org/articles/clinch-river-application-accepted-for-review

https://www.world-nuclear-news.org/articles/energoatom-signs-westinghouse-and-holtec-agreements
Energoatom is pushing ahead with plans with Westinghouse to create a plant for the production of fuel assemblies in Ukraine, and with Holtec for manufacturing plants for small modular reactors and for storage containers for used nuclear fuel.

South Korean SMR design approved by regulator (2024)​

https://world-nuclear-news.org/articles/south-korean-smr-design-approved-by-regulator


Apparently Japan has deployed a 1 MW SMR. Not much information about it.
https://blog.tmcnet.com/blog/rich-t...hers-in-a-new-era-of-micro-nuclear-power.html

Two Yoroi Reactors are already running in northern Hokkaido, powering isolated towns that previously relied on diesel generators. These microreactors are delivering constant, clean electricity with zero carbon emissions, replacing decades-old fossil fuel infrastructure in the process.

Japan’s Ministry of Economy, Trade and Industry (METI) (pictured) has publicly stated its intention to scale deployment, with plans to install 50 additional Yoroi units across rural Japan by 2030. The government sees the technology as a critical bridge between energy security, carbon neutrality, and disaster preparedness — particularly for communities that are difficult to connect to national grids.

Regardless of the fission source, usually U (²³⁵U,²³⁸U), or (²³³U, ²³²Th), one still has to address the fission gases and volatile fission products, which accumulate with burnup. The two decay chains of interest are:

Se > Br > Kr > Rb > Sr > Y
Te > I > Xe > Cs > Ba > La

The volatiles and gases must be contained until the radionuclides to decay to solid products (with higher melting temperature), e.g., Y and La.