Interview at nuclear station 2

[ScottyUK]

I've landed an interview at a British AGR nuclear power station. I'm from a CCGT background so I'm familiar with the standard electrical plant and control systems which exist within a power generation environment. I'm much less clued up on the nuclear side of things, other than having a rudimentary understanding of how the different reactor types work. Does anyone know of any good reference material on the 'Net? I'm more than happy to buy texts etc, but I'd like to get a bit more clued up prior to Monday's interview and on-line is probably the quickest way to do this.

Thanks in advance.



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If we learn from our mistakes,
I'm getting a great education!

 

[electricpete]

I work at a nuke plant in the US. I think UK nuke plants may have some differences. In general I beleive Nuke plants require the same types of calculations as other plants (load flow, short circuit, ampacity analysis, aetc) but heavily documented and maintained relatively up to date through the life of the plant. Some unique protection aspects I have seen is safety-related motors which alarm only (vs trip) on overload, ungrounded electrical systems, double series molded case circuit breakers on cable penetrations to ensure cable is positively isolated upon fault. Also it seems there is a lot of focus on analysis of separation requirements among cables to ensure that single cable faults or fires do not adversely affect redundant safety systems. No doubt you know there are typically more administrative requirements associated with operating, maintaining and modifying the plant to obtain a very high level of assurance that these activities are done properly..

You might also poke around at the nuclear engineering forum on this site or at the US nuclear regulator commission website

http://www.nrc.gov/

All of that is probably not much help to you. Wish I could think of more but I don't know of any really good resources even for US plants.

If they're smart I'm sure they'll hire you faster than the time it takes an N16 atom to decay. Good luck!

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[cuky2000]

ScottyUK,

I have the same impression as other colleagues that you will do very well in the interview.

The electrical principles are the same except that in nuclear applications have some high degree of reliability implementing a rigorous quality assurance of the design, operation and maintenance of the facility. Great emphasis is devoted to the verification of the equipment rating including the effect of nuclear radiation for all electrical components such as cable, apparatus, protective devices etc.

The calculations that normally is not done in the commercial and industrial environment such as seismic withstand capability, fire protection, lightning protection, SC, LV protective device coordination, etc is mandatory for verification and validation by independent parties including the local regulatory agency.

I do not have any info for UK but in the US electrical equipment for nuclear power generation application are rated as Class IE. Enclose check if the enclose IEEE reference standards and other sites that I hope could help you as a general guideline

http://standards.ieee.org/catalog/olis/nuclear.html

http://www.eupen.com/cable/safety/safety0212.html

http://energy.tycoelectronics.com/nuc1/nuclear.pdf

 

[rmw]

Expect things to S-L-O-W down. In the environment in which you have been working, things need to, and do happen fast. Just guessing, you are probably in an environment where there is too much work for too few people to do.

In the nuclear envrionment, for reasons stated above by Pete, and cuky, having to do with reliability and regulation, projects move agonizingly slow, and there are lots of checks and balances. Lots of people looking over your shoulder.

My observation about the nuclear insustry is that they have (historically up to now-this, too may be changing) way too many people involved in every process. I am not meaning to say that this is not proper, and as it should be, due to the nature of the process. It is just an observation.

The same things that are routinely done in a rapid fashion on the fossil side take much longer on the nuclear side.

rmw

 

[rmw]

Oh, and, forgive me, I forgot to say 'good luck on the interview'.

rmw

 

[Laplacian]

A couple of years ago, I happened upon a Canadian government website regarding nuclear technologies and reactors. I thought I bookmarked it, but couldn't find it. My head was swimming with the vast volumes of *.pdf files full of excellent technical information.

I regret that I can't find it, but here are a couple of other sites that may help you:

http://www.nei.org/index.asp?catnum=2&catid=114

http://www.cna.ca/english/publications.asp#Government_Energy

I think I found the website mentioned in the beginning of my post:

http://canteach.candu.org/concepts.html

(good stuff here)

 

[Laplacian]

Sorry, here is the link to complete volumes of information

http://epic.mcmaster.ca/~garlandw/canteach/keyword/course page.htm

 

[electricpete]

Just a few thoughts on Candu reactors.

Candu is a whole different breed than in the US. Candu reactors refuel on-line. US reactors shut down to refuel every 18-24 months.

To my understanding the reason the US never licensed the Candu concept was that heavy water was involved and this material was considered something that should not be widely used due to possibility of falling in the wrong hands.

I don't know how UK reactors compare between Canada and US styles but I would think closer to US.

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[alehman]

I work with a former nuclear plant engineer. I think he would agree with all of the above. There are many more backup systems than a conventional plant. Power distribution systems have multiple levels of redundancy. Monitoring systems are crucial. Commissioning, testing, maintenance and record-keeping are very important. Many types of equipment must be nuclear (IEEE class 1E) rated.

 

[edison123]

Scotty,

I am sure you will do pretty well. Good Wishes.

 

[ScottyUK]

Gents,

Thank you all very much for your responses. It will be some time until I find out whether I'm successful, based on the recruitment process so far. I'll post my experiences here.



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If we learn from our mistakes,
I'm getting a great education!

 

[ausphil]

ScottyUK,

Can I suggest that you change/remove the footer from your posts for a while, just in case they look at this site. I don't know if a prospective employer in the nuclear industry would look favourably on your "education" technique.

Good luck.

 

[itsmoked]

Hahahah!! Good point!

Kiss that job goooooodbye!

 

[Barryng]

I am an Electrical Maintenance Department Supervisor at a US PWR and have been in this industry since 1974. First, realistically, I do not think any reasonable person would have a problem with ScottyUK's footer. Second, there is no real difference in the fundamental design of the electrical power systems except in terms of redundancy, separation, paper trail, and almost overwhelming administrative requirements.

The major issue for someone enetering this industry would be the acceptance of the culture. There are many redunant and intentional barriers in place to prevent inadvertent alteration of the design basis and to assure that the plant is always operating within the envelope of the design basis. These issues are significantly compounded by an extremely high level of concern (and related administrative restrictions) for both radiological and personnal safety.

It is OK to repair something with a like for like but under no cicumstances can the physical facility be changed without a typically cumbersome and time consuming design package. Even temporary jumpers for troubleshooting require a level of independent review. Absolute verbatim compliance with all procedures is mandatory and anything less is not tolerated. No work can be done, even a simple repair, without an approved work package. Individual accountability is held to very high standards. Independent verification and real time independent work observations are an everyday occurence. Then there are the many restrictions and administrative requirements associated with entering areas that that are potentially contaminated or are in radiation fields. All this, plus much more, make for a very frustrating experience for new people, especially those with "fossil plant" experience. Things just don't happen quickly and there are always many barriers to get past to do even the simplest tasks.

Now the other side. I enjoy working in this enviroment. The work is challanging and exacting. The abilities of the people working in this industry is clearly very high. It is very satisfying to consistently work with people that are highly competent, reliable, and accountable.

Having said all this, my only advice to someone entering this industry would be to tell them they absolutely must be willing to except a huge culture change from the expectations of most other industries. Those who fight or even just complain about all the "silly" requirements make themselves and everyone around them miserable.

 

[itsmoked]

Barryng; Nice piece of clear info (it examples your point).

Sounds sort of like the submarine service of power plants.

A star.

 

[mc5w]

There are also some other aspects to reactors. When you scram any reactor or otherwise reduce below about 60% of the previous power level you have an instability problem because the moderator acts as a neutron capacitor. This is more of a problem with graphite and heavy water reactors. In a light water reactors the absorbtion cross section of hydrogen helps to dispose of free neutrons. A free neutron "decays" into a hydrogen atom with a half life of about 12 minutes. This means that it takes about 2 hours to dispose of 99.9% of excess neutrons when the power level is reduced.

For some funny reason the Candu reactor uses Gadolinium injection to scram the reactor. This has to be taken back out using ion exchange resin over a period of several days.

You are going to run into a lot of checks and balances. What really went wrong at 3 Mile Island was that an operator decided that there was not a reason for the emergency cooling system to be operating and manually shut it off. If he had not done that the plant would have saved itself from damage due to a malfunctioning relief valve.

When a warning light or a similar automatic action happens the plant probably is responding correctly to something going wrong. With all of the redundancy and triple checking of design and construction you do not get the equivalent of a medical test that is a false positive.

 

[itsmoked]

That hydrogen is what isotope?

This is the *problem* hydrogen always refered to around reactors?

Gadolinium poisons the entire reaction right? (neutron absorber)

 

[electricpete]

itmsoked - are you a nuke?

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[itsmoked]

No Sir!
Just have a minor in Physics cuz I liked it.
Heck I like anything technical the more the better.

When I was in college a great vacation was driving from power plant to power plant and taking em into technical tours.

Now due to the scummy terrorists I can't even beg a tour into 1MW hydro for my two young adults.

I'm a hundred miles north of Diablo Canyon.

 

[mc5w]

The hydrogen atoms in light water absorb neutrons and turn into deuterium atoms. That is, you can turn light water into heavy water just by throwing enough neutrons at it. In a U.S. power reactor there is usually enough water replacement due to minor leaks that the water is only slightly more heavy than tap water.

When you heat up water you get an acid shift in the PH. The reason why boiler feedwater in a power plant has a PH of about 8 or 9 going into the reheaters is so that the PH will be about 7 in the boiler.

How you get hydrogen bubbles in a reactor is that the water reacts with metals producing metal oxide plus hydrogen. You would get the same thing with say hydrochloric acid at room temperature.