At V.C. Summer our RTP is 2900 MWT.  We have a feedwater flow rate based calorimetric computer program that operates continuously on the plant process computer.  We operate with the goal of maintaining shift average power at or slightly below RTP based on this program.  All of our accident analyses are based on an approximately ±2% reactor power uncertainty which is the overall uncertainty of the calorimetric computer program.  This means that actual reactor power could be as high as 2958 or as low as 2842 MWT when the calorimetric program is indicating 2900 MWT. 

Appendix K uncertainties are not intended to be used as penalties applied to a plant’s licensed thermal power limit. 

Bill Bell

Reactor Engineering

803-345-4389

From: pwrrm@retaqs.com [mailto:pwrrm@retaqs.com] On Behalf Of Adina K Lafrance
Sent: Thursday, January 21, 2010 8:43 AM
To: RETAQS (pwrrm@retaqs.com)
Subject: [Pwrrm] Measured power and uncertanties

 Surry is trying to answer a question this morning regarding power level indications and uncertainties. 

We are stating that within a certain confidence level, that the calorimetric calculation will produce a reactor power output (at RTP) from 98.8 to 101.2% with the rightly calibrated process instrumentation in the calorimetric program (App K).  Half the time the operating power will be above 100%, half the time it will be below 100%.  The opposing opinion is that if we have a 1.2% RTP uncertainty that we operate at or below 98.8% so as to not exceed RTP.  The uncertainties in question relate to the plant computer-none of the redundant indications indicate higher than RTP (most notably delta Ts).  It is also noted that we were told that no other site operates the way we are with regard to uncertainties. 

Can you please tell us how your site operates with regard to uncertainties and your RTP? 

Thank you in advance. 

Adina LaFrance

The significant problems we face cannot be solved at the same level of thinking we were at when we created them.  -Albert Einstein

Nuclear Analysis & Fuel

Reactor Engineer

Surry Power Station

Email: Adina.K.LaFrance@Dom.com

Phone: 757-365-2658

Pager #: 4290

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