ML18093A408
| ML18093A408 | |
| Person / Time | |
|---|---|
| Site: | Salem  |
| Issue date: | 10/01/1987 |
| From: | Corbin McNeil Public Service Enterprise Group |
| To: | NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM) |
| References | |
| NLR-N87184, NUDOCS 8710060443 | |
| Download: ML18093A408 (3) | |
Text
Public Service Electric and Gas Company Corbin A. McNeill, Jr.
Senior Vice President -
Nuclear Pub I ic Service Electric and Gas Company P.O. Box 236, Han cocks Bridge, NJ 08038 609 339-4800 OCT O 1 1987 NLR-N87184 United States Nuclear Regulatory Commission Document Control Desk Washington, DC 20555 Gentlemen:
REQUEST FOR AMENDMENT SALEM GENERATING STATION UNIT NOS. 1 AND 2 DOCKET NOS. 50-272/50-311 This letter is to document conversations held with Mr. H.
Balukjian of your staff regarding PSE&G's License Change Request 87-05, RTD Bypass Removal.
PSE&G will perform pre modification and post modification THOT reading comparisons to confirm scoop mixing assumptions.
This will be done using data from pre and post modification calometrics.
If significant variations exist, PSE&G will reconfirm the validity of the setpoints established for the new system.
PSE&G will make this data available to the staff for their information.
Page 21 of the Licensing report submitted by PSE&G letter dated May 5, 1987, referred to a Tave and
~T deviation alarm.
Mr.
Balukjian questioned how the deviation was determined and an approximation of how much an RTD could vary before an alarm was noted.
The following formulas apply:
Tave Deviation Alarm setpoint between loops:
+0°F, -2°F Loop Tave =
(TH1+TH2+TH3}/3 +Tc 2
Determined for each loop where TH1/TH2/TH3 represents reading from each RTD in a loop and Tc represents the cold leg RTD reading for that same loop.
8710060443 871001 '
PDR ADOCK 05000272 p
PDR l
OCT O 1 1981 Document Control Desk 2
Tave for each loop is then auctioneered to determine the highest Tave*
This is then used as a comparison point.
When any of the othe:i;Tave is more than 2°F below this auctioneered value, the deviation alarm sounds.
AT Deviation Alarm setpoint between loops:
+0°F, -3°F Again, the /.):.T values are auctioneered to determine the highest value.
A reading in any other AT channel more than 3°F below the auctioneered value actuates the deviation alarm.
The deviation alarm setpoints have to account for three major error components:
process measurement accuracy (PMA), sensor accuracy and drift (SA+ SD), and rack accuracy and drift (RA+
RD).
All of these error components are significant when compared to the deviation alarm setpoints.
Typically, the Tave and T
deviation between loops at the Salem plants are in excess of l.5°F and 2.0°F, respectively.
Considering the small margin between alarm setpoint and normal variance between the loops, a deviation alarm would be anticipated whenever a RTD problem (including excess drift or failure) would cause a loop's T hot or T cold signal to further deviate by 1°F.
PSE&G also confirms their intent to replace 2 RTDs per refueling on the lead unit at each of the following two refueling outages.
PSE&G will review the recalibration results from the RTDs removed, as well as other data anticipated to become available on the drift of the N9004 Weed RTDs, prior to making any subsequent, long-range periodical RTD replacements.
Since the replacement RTD would have to be within the allowable deviation from the averaged reading, verification of no significant systematic drift will be obtained.
Should you have any questions, please feel free to contact us.
Document Control Desk 3
C Mr. D. c. Fischer USNRC Licensing Project Manager Mr. T. J. Kenny USNRC Senior Resident Inspector Mr. W. T. Russell, Administrator USNRC Region I Mr. D. M. Scott, Chief Bureau of Nuclear Engineering Department of Environmental Protection 380 Scotch Road Trenton, NJ 08628 f:JGT O 1 1987