Joseph: The following is the V. C. Summer Station response to your questions:

 

1) What are other plants goals/expectations for maintaining power level? (=/- MW or goal); How easy is it to maintain?

    Is there a band within which you operate?

 

The attached file Ops @ the Licensed Limit.doc contains the guidance our operators use for maintaining reactor power as close to the licensed limit (2900 MWT) as practicable.  I have also included a 24 hour plot of data that illustrates our reactor power and feedwater flow rate.  As you will see we typically have minute to minute swings in feedwater flow rate based calculated reactor power in the range of 3 to 5 MWT.

 

 2) How is your secondary calculation performed?  (Averaging Inputs, Instantaneous values, combination) Is it a module

    or program on you plant computer or is it an off-line routine?

 

Our calorimetric power calculation is feedwater flow rate based.  Our new plant process computer now performs this calculation once a second. However, many of the inputs are one minute average values of one second instantaneous values.  The one minute averaging is a holdover from our old (slow) computer that we have had no reason to change.  The calculation does not need to be performed at a one second rate but we do it anyway because our new computer can easily handle it.

 

3) Are your temperature and flow transmitters set specifically for this calculation? (dampening or bias settings)

 

All of the instruments that provide input to the calorimetric are calibrated once every 18 months.  Most also undergo quarterly Op tests.  However, the instruments themselves have no special dampening or bias settings.  All averaging is done by the plant computer.

 

 

4) Are any of your control loops (Feedwater) used in the secondary calorimetric calculation?

 

Our feedwater flow rate transmitters used by the calorimetric computer program also provide protection and control functions as well.  The steam generator level control system uses these transmitters as does our reactor protection system.

 

5) Have you had any issues related to power swings or related to your secondary calorimetric?

 

Yes. As you can see in the attached plot of power and feedwater flow rate we occasionally encounter spikes in feed flow in our A loop.  We are currently trying to understand the cause of these spikes but so far the solution eludes us.

 

Bill Bell

Chemical Engineer

Reactor Engineering

V. C. Summer Station

803-345-4389  

 

 

 

 

Fort Calhoun Station is currently experiencing 3-5 MWth swings (peak-to-peak) in a one hour period to on our secondary calorimetric calculation. This last outage we replaced both S/Gs and refurbished our FW regulation valves.  Prior to this outage our swings were normally 1 MW over 4 hour period. We attempt to keep power at a corporate goal of 1498 MWth (1500 MWth is our rated power level). We do not see these swings on the NI or Delta-T power indications that follow the secondary calorimetric swings.

 

We have not implemented Appendix K using ultrasonic flow measurement for feedwater as of yet.

 

Our Question(s)

 

1) What are other plants goals/expectations for maintaining power level? (=/- MW or goal); How easy is it to maintain?

    Is there a band within which you operate?

2) How is your secondary calculation performed?  (Averaging Inputs, Instantaneous values, combination) Is it a module

    or program on you plant computer or is it an off-line routine?

3) Are your temperature and flow transmitters set specifically for this calculation? (dampening or bias settings)

4) Are any of your control loops (Feedwater) used in the secondary calorimetric calculation?

5) Have you had any issues related to power swings or related to your secondary calorimetric?

 

 

 

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