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kristopher

(29,798 posts)
Tue May 9, 2017, 06:14 AM May 2017

Nuclear power is unreliable

Watts Bar 2 Off Until Summer; Concerns over Safety Culture Persist
May 4, 2017
By Wayne Barber

The Tennessee Valley Authority’s Watts Bar 2 nuclear unit, which went offline in March because of an equipment problem, is expected to remain down until sometime this summer, according to CEO Bill Johnson.

The 1,100-MW reactor, the nation’s newest, had begun operation in October 2016. It has been out of service since March 23 following a structural failure in the unit’s condenser, a three-story-high heat exchanger.

Because of the tight space inside the condenser, “the logistics of doing this work are quite tricky,” Johnson said during a May 2 conference call on the federally owned utility’s financial results. He said he could not be more specific about the return-to-service date.

...

In response to a question, Johnson said that TVA has been working for more than a year to address concerns raised by the Nuclear Regulatory Commission and the corporation’s inspector general about the safety culture at Watts Bar. The commission cited a “chilled work environment” in a March 2016 report.

Inspector General Richard Moore said last month that he remained unconvinced that “TVA corrective actions will bring about sustainable change.” ...

https://www.rtoinsider.com/watts-bar-tva-clean-line-42514/


Intermittent or variable?
by Craig Morris
23 Jan 2014
Wind and solar power are often considered unreliable, especially by their detractors. But Craig Morris recently realized he needed to change his terminology – after learning how intermittent conventional power plants are....

...while production of wind and solar power fluctuate (to use the German term), giant amounts of renewable generation capacity do not simultaneously go off-line.

Conventional plants can fail quickly. In a recent storm that hit Europe, the social media world was concerned about wind turbines being blown away, but I could not find any news of such a thing happening. We do know that the Ringhals nuclear plant, with a capacity of 878 MW, failed completely, however, as one of its blocks did again just a few weeks later.

In North America, the recent Arctic cold knocked out power plants across the country, with 39,500 MW going off-line in a single day within the PJM grid, 21 percent of PJM’s total generation capacity. Roughly 19,000 MW was coal plants, followed by 9,000 MW of natural gas turbines, 1,600 MW of nuclear (probably a single plant), and “nearly 1,500 MW of wind.” (One wonders whether it was the wind turbines themselves that failed or grid connections to the turbines.)

The PJM area was not alone, either....
https://energytransition.org/2014/01/intermittent-or-variable/
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Nuclear power is unreliable (Original Post) kristopher May 2017 OP
Except compared to everything else of course FBaggins May 2017 #1
FWIW: A more recent, relevant publication OKIsItJustMe May 2017 #2
Yes renewables are variable, but they don't drop 100% instantly... kristopher May 2017 #3
where's NNadir when you need him? ccarrick May 2017 #4

FBaggins

(27,407 posts)
1. Except compared to everything else of course
Tue May 9, 2017, 03:04 PM
May 2017

This notion that anything short of 100% reliable is equally "unreliable" is one of the more ridiculous claims.

All forms of electricity generation have some level of failure (http://www.nrel.gov/docs/fy13osti/59111.pdf). The knock on variable renewables isn't that they lack 100% reliability... it's that they can't be counted on even when they're 100% operational.

while production of wind and solar power fluctuate (to use the German term), giant amounts of renewable generation capacity do not simultaneously go off-line.


As you should know... Those same Germans hit a reportedly record high in solar/wind generation a few days back (~46.5 GWs)... but in the same 24-hr period also fell to less than 1.7GW. I can't wait for the interesting spin re: how that isn't "giant amounts" that are "simultaneously off-line"

OKIsItJustMe

(20,261 posts)
2. FWIW: A more recent, relevant publication
Tue May 9, 2017, 03:42 PM
May 2017
http://www.nrel.gov/docs/fy15osti/63038.pdf
[font face=Serif][font size=5]USING WIND AND SOLAR TO RELIABLY MEET ELECTRICITY DEMAND[/font]

[font size=4]LEVERAGING RENEWABLE ENERGY TO ACHIEVE LONG-TERM ADEQUACY[/font]
[font size=3]An important aspect of power system planning is ensuring that adequate generation capacity exists to meet electricity demand during all hours of the year. Mechanical failures, planned maintenance, or lack of on-demand generating resources (especially for variable renewable resources) may leave a power system with insufficient capacity to meet demand. Grid planners project future peak demand patterns and estimate the relative contribution of each generator towards achieving a reliable supply of energy. When generating during peak demand periods, variable renewable energy (VRE) such as wind or solar PV provides capacity value to the system. By providing capacity value, VRE can help to defer capital investments in traditional generation and transmission infrastructure.[/font]

[font size=4]CALCULATING CAPACITY VALUE[/font]
[font size=3]Determining the capacity value of VRE is more complex than it is for conventional generation technologies due to the inherent variability of these resources. The simplest way to calculate capacity value of a renewable generator is to examine how well VRE generation aligns with regional demand patterns. This approach considers the output of a generator over a subset of periods during which the system faces a high risk of an outage, such as the 10 to 100 hours of highest net load in a year |1|. The result is expressed as either a capacity value (kW, MW) or as the fraction of the renewable generator’s capacity that adds to system reliability or can offset conventional capacity (see sidebar).

More accurate approaches used by utilities and system planners employ detailed reliability-based metrics to assess capacity value. One widely used statistical approach calculates the effective load-carrying capacity (ELCC) of additional generation. The ELCC of a generator is defined as the amount by which the system’s loads can increase when the generator is added to the system while maintaining the same system reliability. In this case, system reliability can be described using two metrics: loss of load probability (LOLP) and loss of load expectation (LOLE). The LOLP is defined as the probability of a loss-of-load event in which the demand is greater than available generating capacity during a given period |2|. The LOLE is the sum of the LOLPs during a planning period—typically 1 year. LOLE gives the expected number of periods in which a loss-of-load event occurs. Power system planners aim for a certain LOLE target, such as 0.1 days/year or 0.1 events/ year |3|. Figure 2 illustrates the steps used to calculate the full ELCC of an added renewable generator.

Studies have found a large range in capacity values, ranging from 5% to 40% for wind and 5% to 75% or higher for solar PV |2|, |4|, |5|. Once capacity value is known, a monetary value per unit of installed VRE capacity can be calculated using a variety of approaches |1|.

…[/font][/font]

kristopher

(29,798 posts)
3. Yes renewables are variable, but they don't drop 100% instantly...
Tue May 9, 2017, 04:53 PM
May 2017

without warning, for months and even years at a time. Japan still has 51 reactors shut down more than 6 years after the disaster there.
https://www.theguardian.com/news/datablog/2011/mar/14/nuclear-power-plant-accidents-list-rank#data

The industry is rife with reactors that have been offline for months and years at a time. But luckily for their stats, those extended shut downs and the sometimes decades long delays to complete initial construction are not considered in their load factor claims.



On the subject of renewables: https://www.rmi.org/insights/reports/economics-load-defection/

How are things going in Texas, Georgia and South Carolina?

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