ML19321A543

Forwards Info Re Sys Description of Core Thermocouples in Response to TMI-2 Action Plan Item II.F.2 on Inadequate Core Cooling Instrumentation

ML19321A543
Person / Time
Site:	Farley
Issue date:	07/17/1980
From:	Clayton F ALABAMA POWER CO.
To:	Schwencer A Office of Nuclear Reactor Regulation
References
NUDOCS 8007230592
Download: ML19321A543 (5)

Text

Alabama Power Company 600 North 18th Street

. . Post Office Box 2641 Birmingham. Alabama 35291 Telephone 205 323-5341 nk hbCWc"?,%C, Alabama Power July 17, 1980 rne scornern electne system Docket No. 50-364 Director of Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission Washington, D.C. 20555 l Attention: Mr. A. Schwencer RE: Joseph M. Farley Nuclear Plant - Unit 2 TMI-2 Action Plan Ir2ms Gentlemen:

As requested by the NRC staff, Alabama Power Company submits the enclosed information regarding the system description of the core thermocouples used in Plant Farley. This information was requested to address Action Plan Item II.F.2 on Inadequate Core Cooling Instrumentation.

If you have any questions concerning this item, please advise.

Very truly yours,

~

n 3- . a-

,A < _u.4' w ,*

F. L. Clayton, Jr.

FLCJr/RLG:aw Enclosure cc: Mr. R. A. Thomas Mr. G. F. Trowbridge Mr. L. L. Kintner, W/ Enclosure Mr. W. H. Bradford Mr. Ed Reeves, W/ Enclosure k

8007;330 b L

DESCRIPTION OF INCORE THERMOCOUPLE !! STEM Thermocouples:

The Thermocouple System utilizes 51 thermocouples, positioned to measure fuel assembly coolant outlet temperature at preselected core locations (FSAR Figure 4.4-22A). The thermocouples are the chromel-alumel type and have an accuracy of i 20F.

Thermocouple Routing and Seal Assemblies:

Each thermocouple is 1/8-inch (nominal) diameter, stainless steel sheathed, l aluminum oxide insulated- lth the trailing end terminated in a male thermo-couple connector. The tht.1noelectric characteristics conform to the K ,

calibration curve within i 20F from zero to 5300F and within t 3/8 l percent of point from 530 to 7000F. Each thermocouple is supplied to the l specific length required for its assigned location.

The sheaths, which ar-e renovable, are routed in guide tubes which position -

the thermocouple end at the selected core location. The guide tubes extend the entire distance from the core location to the seal assemblies.

The guide tubes are routed to one of five instrument ports used for the l thermocouples. The individual thermocouple guide tubes are enclosed ir j a thermocouple port column which protrudes through the reactor head instru-  :

ment port. The individual thermocouple guide tubes are sealed to the

,[ thermocouple port column. The thermocouple sheath is sealed to the guide tube by means of a swage lock seal. l The sealing between the head and the instrument port column is accomplished ,

by the use of two conoseals. During a normal head removal only these l seals must be broken. 1 The sealing assembly consists of the conoseals and seats, male flange, Jack screw assembly, reactor head penetration adapter, and the carbcn steel clamp. To describe how this sealing assembly f, unctions a description of the installation procedure follows:

After the head is in place the thermocouple port column is protruding through the reactor vessel head. The conoseals are placed on the seating surfaces shown on Figure IV-2.7, and the male flange is slipped down over the thermocouple port column. A hydraulic ram is then used to seat the conoseals. With the ram in place the carbon steel clamp is installed and tigh tened. The ram is then removed and the carbon steel clamp is then holding the assembly together. The jack screw plate is then installed by removing the split ring and sliding the jack screw plate down over the thermocouple then replacing the split ring and tightening the jack screws. ,

The individual thermocouple wires are then separated and routed to either l of two reference junctions. The thermocouple reference junction boxes are provided to permit transition from chrcmel-alumel thermocouple extension wiring to copper field wiring. These units provi.de a controlled 1600F temp-erature reference for the'incore thermocouples. ^Each reference junction box.contains three platinum resistance tenperature detectors (RTD). Two of the RTD's from each unit are connected directly to the plant.computar

,a

Description of Incore Thermocouple System (Cont'd) .

Page 2-for monitoring of reference junction temperature; the third RTD in each

_. unit is an installed spare.

The selection of the thermocouples to be connected to each reference junction was made to eliminate the possibilit;y that a single failed reference

~

junction would totally negate the value of the readings received from the ti:ermocouple system. In the event a reference junction does fail, the themocouples connected to the remaining reference junction hhve been ^

chosen so as to provide a meaningful representation of the core tempera-ture;.

Incore Thermocouple Control Cabinet:

All of the control equipment for the Thermoccuple . System is located on a rack in the control room. A multipoint precision indicator has been -

provided to indicate the temperature sensed by the thermocouples. Only one thennoccuple at a time can be connected to the indicator. Switches have been provided on the front of,and above,the indicator to select that thermocouple desired. to be read.

- An additional selector switch located on the front of the panel allows either the low (0-4000F) or high (400-7000F) range easuring circuit r_ to be used. Besides being directed to the indicator, the thertnoccuple

> outputs are also applied to the plant computer. l l

4 e

e

1 7f D T u-T T D TO T D TD T TD w-T T D D D T D D T D T T D TD TD g T TD D T D ver=

T T- D D D T D D TD T T T D T TD D T D T TD T D T D TD D TD TD T D TD T D T TO TD D -

D T .TD T D TD l e

[ TO TD 4 ,

TD D T D T T l i

1 f.*= T =

hv THERMOCOUPLE (51) .

D = MOVABLE INCORE DETECTOR (50)

AMEND. 62 2/4/77 A!!END. 61 1/14/77 e.

Esf ALABAMA POWER COMPANY JOSEPH M. FARLEY NUCLEAR PL ANT FINAL SAFETY ANALYSIS REPORT UNIT 2 ,

en. DISTRIBUTION OF b535 IN-CORE.!NSTRUMENTATION FIGURE 4.4-22A l

1 l

' ! 'Thermocouplo Connector  ; \ To M f:renca Junction CJ -

&- High Pressuru Seat s'* N}' t l .

([ , i~

Q

=

l, .1

.I 1

M Jack Screw 1 i s

,ki &

Seal Assembly y Conoseats ,

f I .h (Seat Point)

• ,J j ,

I i

l

,+ l

.~

V l

.M'c & Clamp

%,~,

Thermocopple Port __ m I 9 Column q , ] i.4 Attachment to Reactor

.l r Vessel Head Penetratle

i 1

.s.

Guide Tube > ,

S '* ' "' *" S ' * * ' S "* * *'

-fN E RMOCOUPLE . ,

R OUTING GENERAL (' ,

i

~_g c!o",","E RRANGEMENT ;gZGURE IV-2J