ML19221A169
| ML19221A169 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 04/11/1979 |
| From: | Ackermann N SPECIAL INSTRUMENT GROUP |
| To: | |
| References | |
| NUDOCS 7905190230 | |
| Download: ML19221A169 (3) | |
Text
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THI-2 REACTOR CORE STATUS If1STRUMEi4 TAT 10N JATA PACKAGE Prepared By:
fiorbert J. Ackermann, Jr.
Special Instrument Group Coordinator April ll, 1979 79051909-30 qp e
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4/10/79 NJA TMI-2 REACTOR CORE STATUS INSTRUMENTATION DATA PACKAGE Numerous measurements have been made during the past 12 days that ca. help in inferring the status of the TMI-2 reactor core.
The purpose of this document is to report all of these measurements to provide as completely and accurately as possible the pertinent information.
This data will be re,;
.
- by instrument cl a s s.
1.
Incore Thermocouples 52 Cr/Al thermocouples are located in incore instrument thimble positioned approximately 6" above the active core.
Diagnostic measurements (loop resistance, time trace studies, trend analysis and spectral analysis) indicate that 49 of tnese are functioning and appear to be healthy, 2 (8F and 2L) are suspect (reading low and one noisy) and 1 is failed (13L).
2.
Incore Self-Powered Neutron Detector There are 52 instrument thimbles in the core that contain 7 self-powered neutron detectors '(SPND) in each thimble at levels in incFe; from the core bottom as follows:
Inches From level
_ Core Bottom 1
10 2
30 3
50 4
70 5
90 6
110 7
130 Diagnostic measurements (loop resistance and current) on these SFND's indicate that 37 of these are not f ailed (high resistanc.es and measurable currents) with 20 of 52 at level 1 and 15 of 52 at leval 2,1 at level 3 and 1 at level 5 (see attachment 1 for detailed location information).
The failed SPND's show 10 loop resistances indicating probably failed sheaths and moisture in tht cable.
3.
Excore - Ur ompensated Ion Chambers Eight uncompensated ion chambers (4 upper and 4 lower) are positicr.ed abcut 6" cutside the reactor vessel.
Idc measurements have been made on these chambers as follows:
Idc (nanozmp; 8.8 R/hr/na)
Quadrant (relative pemp)
Upper Lower WX (2A) 2.8 2.1 e
a7c 1,0 LJJ i3 ZX (lA) 2.6 2.4 WY (2B) 2.2 2.0 ZY (lB) 1.85 1.8
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' TMI-2 REACTOR CORE STATUS INSTRUMENTATION DATA PACKAGE Page 2 4.
Startup Range Detector (BF un ers) 3 There are two startup range detectors located about 6" outside the reactor vessel.
These detectors have been verified to be responding to neutrons (integral bias curve, discriminator setting).
The neutron source from the core at this time is a combination from the startup sources (Antimony, Seryllium and Americium) and T,n reactions in Deuterium and then from multiplication in the core.
The detectors were reading 40 cps on 4/9/79 and were showing slight decay daily.
5.
Moveable Incore Detector Each instrument thimble has a hollow tube for insertion of a moveable incore SPND.
51 were capped off and one (N-8) had the moveable SPND parked.
The SPND was inserted on 4/9/79 and moved to about 3 f t. (t--3 in.) up into the core before it was blocked for any further insertion.
The probe was backed off and reinserted to this same point several times indicating a firm blockage at this point 1Jo LJu l
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