B. Rouben

McMaster University

6P03

Course Project

Due 2015March31

This project is worth 20 marks. Your Project mark will be added to your Assignments, Midterm and Final Exam marks, and your final course mark will be renormalized from a maximum of 120% to a maximum of 100%.

Note: See further below the Objectivesto be fulfilled for Parts A, B, C.

This project is an exercise on load cycling (also sometimes loosely called load following).

Purpose of Project:Electricity requirements are lower during the night and during the week-end. Some plant operators may wish to respond to this demand by operatingtheir generating station in load-cycling mode. Is it possible to operate the CANDU reactor in load cycling on a daily basis, within the parameters defined in the project statement?

Part A

For instance, consider the following 24-hour cycle:

  • Start on Monday evening, 7:30 pm, assuming that the reactor has operated at 100% Full Power (FP) for a very long time, so everything is in equilibrium
  • Reduce power linearly to 60% FP in 1 half hour [time is now 8:00 pm]
  • Operate for 10 hours at 60% FP[time isnow Tuesday 6:00 am]
  • Increase power linearly to 100% FP in 1 half hour [time is now Tuesday 6:30 am]
  • Operate 13 hours at FP [time is now Tuesday 7:30 pm].

Use the “Xenon Effects” learning module, the differential equations for X(t) and I(t) [which include the flux, which you should take as proportional to power], and the xenon reactivity (or excess reactivity) in terms of X(t):

  • Write an EXCEL file (or write a computer program) to calculate the excess xenon load (relative to the steady-state value of –28 mk), using (for example) a quarter-hour time step t as “integrating” time step
  • Ignore any other reactivity components in the calculation
  • What is the maximum ExcessXenon Load(positive or negative) during this cycle? Also, what is the Excess Xenon Load at the end of the 24-h cycle? Is it back to essentially 0? If it is not, what can be done to regain the desired state of “zero reactivity”?
  • Plot the excess xenon load over the 24-h cycle.

cont’d

Part B

Now assume that the 24-h cycle is to be repeated without a stop 3more times (from Tuesday 7:30 pm to Friday 7:30 pm).

  • Adapt your EXCEL file or computer program to calculate the transient over the 4 full days(from Monday 7:30 pm to Friday 7:30 pm)
  • Plot the excess xenon load over this period
  • What is the excess xenon load at the end of each 24-h period? Is there a pattern emerging?

Objective of Parts A, B:

  • Write a report to show all your results and answer the questions above.
  • Explain whetherit is possible to maintain the reactor critical throughout the period of time considered, with the following available devices:
  • Up to +2.5 or -2.5 milli-k in the zone-control compartments
  • Up to 8 banks of adjusters, each bank worth 2.0 milli-k (total of all 8 banks = 16 milli-k)
  • Up to 0.5 ppm of moderator boron (1 ppm of boron is worth -8 milli-k)
  • If it is not quite possible, what rule or value would need to be relaxed in order to be able to maintain criticality at all times?

Part C

  • Starting on Friday at 7:30 pm, reduce power linearly to 60% FP in 1 half hour [time is now 8:00 pm] and keep operating the reactor throughout the week-end at 60% FP, until Monday 6:00 am (i.e., 58.5 hours at 60% FP).
  • Raise power to 100% FP [time is now Monday 6:30 am]
  • Operate at 100% FP for 13 hours [time is now Monday 7:30 pm, i.e., a 1-week cycle has passed]

Objective of Part C:

  • Similar to that of Parts A & B, i.e., to determine whether it is possible to maintain the reactor critical throughout the 7-day period (no difference in the available reactivity devices)
  • In your results, show explicitly the times when each adjuster bank has to be moved (out or in), and when boron has to be added or removed (assuming “instantaneous” addition or removal).
  • All in all, do you consider this a practicable weekly load cycle? Explain.
  • Whether or not you answered yes to the last question, repeat the exercise with a few different values of the low power in the cycle (i.e., different from 60%), everything else being constant, to determine the lowest value of the low power for which the load cyclingcan be performed.