ML20085G960
| ML20085G960 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 07/09/1973 |
| From: | Eric Thomas TENNESSEE VALLEY AUTHORITY |
| To: | Oleary J US ATOMIC ENERGY COMMISSION (AEC) |
| Shared Package | |
| ML20085G945 | List: |
| References | |
| BFAO-732W, NUDOCS 8308290546 | |
| Download: ML20085G960 (2) | |
Text
I w
t/
v TENNESSEE VALLEY AUTHOptiTY t~~3n' CHATTANOOGA, TENNESSEE i- [r 37401 L
.. W.
_.1 m
'cP \\
- /
sy'yjgKQ%
C PARTNE ASHIP July 9, 1973
- gj g/gy UM I
MM-
- o Yr
/, !h,/ sg }
A
-r W
~
"gd Mr. John F. O' Leary, Director 7 9%jQ Directorate of Licensing k
6 U. S. Atomic Energy Commission fj Washington, DC 20545
\\$
Dear Mr. O' Leary:
Subject:
TEUNESSEE VALLEY AUIIIORITY - BROEINS FERRY NUCLEAR PIANI' UNIT 1 - DOCKET NO. 50-259 - FACILITY OPEPATING LICENSE DPR ABNORMAL OCCURRENCE REPORT BFAO-732W The purpose of this report is to provide details concerning the discovery of disconnected high-voltage cables in seven (7) of the eight (8) IRM channel drawers of unit 1 during initial fuel loading on June 29, 1973 Description of Incident On June 29, 1973, at about 2:45 p.m. CDT, IRM channel F developed some abnorml random noise spikes over short-time intervals. Fuel loading was immediately discontinued, and an instrament engineer was called to investigate the problem. It was evident that the detector high-voltage cable was not connected to this IFJ4 drawer when it was inspected. The high-voltage cable was immediately reconnected. In addition, all cther IRM channel drawers were immediately inspected.
A total of 7 out of 8 channels were found disconnected at the detector high-voltage cable connector "J7" inside their IRM drawers.
Channel D was the only IRM channel found to have all of its drawer cables connected properly.
Investigation and Corrective Action All disconnected IRM high-voltage cables were immediately reconnected, and a study of the problem was initiated.
The vendor informs us that a disconnected high-voltage cable will reduce IRM circuit sensitivity, but it will not prevent IBM neutron monitoring nor its capability to function in the reactor protection j
system (RPS). Belcw normal ionization potential due to the loss of high-voltage excitation reduces IRM detector collection efficiency but does not eliminate neutrcn monitorin5 When the channel is in
/
6 E
8308290546 730703 p
( \\
PDR ADOCK 0:!O00259 j(
J PDR S
5371 COPY SENT REGION
_j _. +
j
2 Mr. John F. O' Leary Ju4 9, 1973 TENNESSEE VALLEY AUTHORITY - BRORUS FERRY HUCIEAR PIANT UNIT 1 - DOCKET H0. 50-259 - FACILITY OPERATING LICENSE DPR ABNORMAL OCCURRENCE REPORT BFAO-732W
" range 1, it possesses its highest sensitivity with or without high-Based upon this information, the required voltage excitation.
fuel-loading, non-coincident, IRM-RPS trip point was preserved with disconnected high-voltage cables but at a point approximately 30 percent higher than expected in range 1.
A review of past surveillance test results indicated that two sections o'f the surveillance instruction-4.12, Range Correlation, and 4.13, These sections cannot be per-Amplifier Gain--were not performed.
formed until reactor power is within APRM range and thus was exempted Unfortunately, the cognizant reviewer by the cognizant reviewer.
overlooked the fact that the exempted section 4.13 contains instructions for reinstalling the IRM drawers at the conclusion of surveillance instruction SI 4.2.C-3B.
Subsequent IRM functional tests (SI 4.2.C-3A) wouM not indicate a disconnected high-voltage cable, and thus the cognizant reviewer was unable to detect any abnormal symptoms.
Surveillance instruction SI 4.2.0-3B will be revised to assure proper restoration of IRM drawers following both pre-power and normal power surveillance testing.. Additionally, when the reactor reaches sufficient pcwer, we will confirm by special test that a disconnected high-voltage cable in an IRM drawer reduces detection censitivity but does not prevent' neutron-monitoring.
To confirm proper IRM operation, a special IRM test procedure was
'Enis prepared, approved, and performed on all eight IRM channels.
wasnecessarytosatisfypreprequisite5.3.2-(TCR-3)ofStartupTest Instruction (STI) 3, Fuel Loading. Upon receipt of satisfactory test results and a review of all prerequisities for each startup test in progress, the Plant Operations Review Committee (PORC) authorized the continuation of unit 1 initial fuel loading at 1:15 a.m. CDT on June 30, 1973
.Very truly yours, TENNESSEE VALLEY AUTHORITY
-n
(
'bty,f Thomas
- Director of Power Production CC: Mr.. Norman C. Moseley, Director.
Region II Regulatory Operations Office, USAEC' 2,30 IPeachtree > Street, JM.
Atlanta, Georgia 30303
_