ML20215J679
| ML20215J679 | |
| Person / Time | |
|---|---|
| Site: | Catawba  |
| Issue date: | 10/10/1986 |
| From: | Tucker H DUKE POWER CO. |
| To: | Grace J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| NUDOCS 8610270149 | |
| Download: ML20215J679 (3) | |
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lO DUKE POWER GOMIhNY I*.O.DOx 33100 CIEAltLOTTE, N.C. 28242 IIAI, IL TUCKER TELEPIIONE vw.e....somwr (704) 373-4531 3 0t1 20 e 6; 1 October 10, 1986 Dr. J. Nelson Grace, Regional Administrator U. S. Nuclear Regulatory Commission Region II 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30323
Subject:
Catawba Nuclear Station RII/GBZ 50-413/86-23-01 50-414/86-25-01
Dear Dr. Grace:
The attached report contains the results of further analyses which were to be completed as described in Rev. I to our response to the subject violation dated September 2, 1986. This report confirms completion of items 3h and 4e of our response, and confirms to our satisfaction that the impact of the system dead-time, greater than 10%, did not significantly affect the results of Gaseous Waste Releases during the period February 21, 1986 to May 23, 1986.
Very truly yours, MAR Hal B. Tucker LTP/35/ sib Attachment xc: NRC Resident Inspector Catawba Nuclear Station 8610270149 861010 PDR ADOCK 00000413
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4 CATAWBA NUCLEAR STATION Followup Report on Items 3b and 4c of
~
Response to Violation 50-414/86-23 and 50-414/86-25 Revision 1 - Dated September 2, 1986 i
j On 9-9-86 a 4600cc Marinelli Gas Beaker Sample was taken from Wasta Gas Decay Tank 'D' (WGDT-D). The sample was analyzed three times, 600 seconds each time, and on HpGe Detector #24-P-94VC (This is the same detector on which the original samples were counted with 20+% dead-time). The resulting dead-time was 9.7%.
The isotopes that were identified for the Test comparison were Xe-133, Xe-133m and Xe-131m (Due to time from Unit 1 and 2 Shutdown, Xe-135 was not present).
A Cs-137 point source (89 pC1) was introduced with the Marinelli in three i
increments to perform analyses that produced dead-times of 16.6%, 24.4%,
and 34.3% (Three counts were performed at each dead-time). Ratios of the average Test activities were calculated against the average control WGDT-D activities (See attachment). The results showed that through the increased 4
dead-times, Xe-133 ratios were essentially 1.0 and based on the consistency and relative concentration of the Xe-133, the dead-time " corrections" for Xe-133m and Xe-131m were insignificant.
The three " worst case" Unit 1 VQ samples, analyzed on 4-24, 25, 26-86 with dead-times of 23%, 22.1% and 24.4%, respectively were then reviewed to establish l
the percent of total activity for the three isotopes Xe-133, Xe-133m, and i
Xe-131m (See attachment). The ratios from the Test WGDT-D activities (24.4%
dead-time) were applied to the percentages of the three VQ samples' activities.
An average of 1.13% increase in activity determination resulted by " correcting" for the high dead-time of the three VQ samples.
l Therefore, the impact of the system dead-time, greater than 10%, did not significantly effect the results of Gaseous Waste Releases during the period 2-21-86 to 5-23-86, i
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Average WGDT-D (uCi/cc) Test (9-9-86)
Xe-133 Xe-133 Xe-131m Dead-Time OR 1.182E-03 5.364E-06 1.452E-05 (9.7%)
6 1.187E-03 6.227E-06 1.584E-05 (16.6%)
0 1.004 1.161 1.091
(
Orig.)
s s) 1.181E-03 7.008E-06 1.826E-05 (24.4%)
RATIO
.999 1.306 1.258 (Test / Orig.)
C 3) 1.176E-03 7.373E-06 1.84cs-05 (34.3%)
.995 1.37 1.273 (T
Orig.)
I 4
Unit i VQ (4600cc) pCi/cc Xenons
% of Total ta Act M ty
% of Total With Correction Diff.
4-24-86 3.588E-03 99.56 98.39 1.17 4-25-86 3.422E-03 99.54 98.42 1.12 4-26-86 3.258E-03 99.64 98.54 1.10 I
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