Desktop Instruction –
Method to Adjust IST Data to the EDG Frequency Administrative Limit to
Verify that the Result Remains Within Surveillance Acceptance Criteria
PURPOSE
This method considers the effects of variations in EDG frequency on the operation of
safeguards pumps that can be loaded on the EDGs. It provides a check to verify the
safeguards pumps remain operable considering the administrative limit on the EDG
frequency range from 59.5 Hz to 60.5 Hz.
The evaluation adjusts IST data using pump affinity laws and compares the results to
surveillance procedure acceptance criteria. This evaluation provides reasonable
assurance that the components affected by EDG frequency variation can fulfill their
functional requirements.
BACKGROUND
Technical Specification 3.8 (specifically SRs 3.8.1.6 and 3.8.1.9) require EDG frequency
to be within a range of 58.8 to 61.2 Hz. This range in frequency is +/- 2% of 60Hz. The
effects of this frequency variation were not previously considered in analyses for system
performance. This method will consider the affects of a frequency range from 59.5 Hz to
60.5 Hz on the performance of safeguards pumps.
The frequency effects on motor and centrifugal pump operation are:

Motor speed is proportional to frequency.
n2/n1 = Hz2/Hz1

Centrifugal pump flow rate is proportional to motor speed.
(n2/n1) = (Q2/Q1)
Thus, if the EDG frequency is at 59.5 Hz/60 Hz or 0.9917, then the pump flow
rate could be reduced by approximately 1%.

Centrifugal pump discharge pressure is proportional to motor speed squared.
(n2/n1)2 = P2/P1
Thus, if the EDG frequency is at 60.5 Hz/60 Hz or 1.0083, then the discharge
pressure could be increased by approximately 1.0167%.
Page 1 of 2
D:\533561246.doc
Desktop Instruction –
Method to Adjust IST Data to the EDG Frequency Administrative Limit to
Verify that the Result Remains Within Surveillance Acceptance Criteria
METHOD
1.0
2.0
3.0
4.0
Obtain the completed SP and its IST data.
Determine if the SP acceptance criteria is:
2.1
A defined range of numerical values for TDH, or
2.2
A graphical solution that uses a plotted point of flow and TDH.
If it is 2.1, then go to step 4.0; otherwise, verify it is 2.2 and go to step 5.0.
Adjust the TDH value to check that it remains within the lower and upper
acceptance criteria.
4.1
For the lower limit, multiply the TDH data by 0.9834. This value
defines the 59.5 Hz lower performance point.
4.2
For the upper limit, multiply the TDH data by 1.0167. This value
defines the 60.5 Hz upper performance point.
4.3
Compare these values to the SP acceptance criteria.
4.4
If they remain within the acceptance criteria, then document the
acceptable result in the comments section of the SP. If either one
is outside of the acceptance criteria declare the pump inoperable
and initiate a CAP.
Head Correction Value
5.0
Lower
0.9834
Upper
1.0167
Adjust the head and flow values that are plotted to obtain a graphical solution to
check that the point remains within the lower and upper acceptance criteria.
5.1
For the lower limit, multiply the TDH data by 0.9834, and the flow
data by 0.9917. These values define the 59.5 Hz lower
performance point.
5.2
For the upper limit, multiply the TDH data by 1.0167, and the flow
data by 1.0083. These values define the 60.5 Hz or upper
performance point.
5.3
Plot these points on the figures for the SP acceptance criteria.
5.4
If they remain within the acceptance criteria, then document the
acceptable result in the comments section of the SP. If either one
is outside of the acceptance criteria declare the pump inoperable
and initiate a CAP.
TDH Correction Value
Flow Correction Value
Lower
0.9834
0.9917
Page 2 of 2
D:\533561246.doc
Upper
1.0167
1.0083