ML19253A459
| ML19253A459 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 04/11/1979 |
| From: | Ackermann N METROPOLITAN EDISON CO. |
| To: | |
| References | |
| NUDOCS 7909100055 | |
| Download: ML19253A459 (3) | |
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I THI-2 REACTOR CORE STATUS INSTRUMENTATION DATA PACKAGE Prepared By:
,J Norbert J. Ackermann, Jr.
Special Instrument Group Coordinator i
April 11, 1979 N&roq3--
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4/10/79 NJA TMI-2 REACTOR CORE STATUS INSTRUMENTATION DATA PACKAGE Numero's measurements have been made during the past 12 days that can 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 reported by instrument cla s s.
1.
Incore Thermocouples 52 Cr/Al thermocouples are located in incore instrument thimble positioned approximately 6" above the active core.
Diagnosti c measurements (loop resistance, time trace studies, trend analysis and spectral analysis) indicate that 49 of these 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 (SPhD) in each thimble at levels in inches 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 SPND's indicate that 37 of these are not failed (high resistances and measurable currents) with 20 of 52 at level 1 and 15 of 52 at level 2, I at level 3 and I at level 5 (see attachment I for detailed location information).
The failed SPND's show low loop resistances indicating probably f ailed sheaths and moisture in the cable.
3.
Excore - Uncompensated Ion Chambers Eight uncompensated icn chambers (4 upper and 4 lower) are positioned about 6" cutside the reactor vessel.
Idc measurements have been made on these chambers as follows:
Idc (nancamp; 8.8 R/hr/na)
Quadrant (relative pump)
Upper Lower WX (2A) 2.8 2.1 ZX (1A) 2.6 2.4 WY (2B) 2.2 2.0 ZY (lB) 1.85 1.3 331350
TMI-2 REACTOR CORE STATUS INSTRUMENTATION DATA PACKAGE Page 2 4.
Startup Range Detecto.- (BF Counters) 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, Beryllium and Americium) and T,n reactions in Deuterium and then from mul tiplication in the core. The detectors were reading 40 cps on 4/9/79 and were showing slight decay daily.
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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.
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