2CAN018701, Advises That Environ Qualification Testing of Incontainment Cabling & Connectors for Core Exit Thermocouple Sys Completed,Per NUREG-0737,Item II.F.2 & in Response to NRC Transmitting Safety Evaluation
| ML20207N353 | |
| Person / Time | |
|---|---|
| Site: | Arkansas Nuclear  |
| Issue date: | 01/02/1987 |
| From: | Enos J ARKANSAS POWER & LIGHT CO. |
| To: | Knighton G Office of Nuclear Reactor Regulation |
| References | |
| RTR-NUREG-0737, RTR-NUREG-737, TASK-2.F.2, TASK-TM 2CAN018701, 2CAN18701, NUDOCS 8701140149 | |
| Download: ML20207N353 (6) | |
Text
ARKANSAS POWER & LIGHT COMPANY POST OFFICE BOX 551 LITTLE ROCK, ARKANSAS 72203 (501)371-4000 January 2, 1987 2CAN018701 Mr. George W. Knighton, Director PWR Project Directorate No. 7 Division of PWR Licensing - B U. S. Nuclear Regulatory Commission Washington, DC 20555
SUBJECT:
Arkansas Nuclear One - Unit 2 Docket No. 50-368 License No. NPF-6 NUREG-0737, Item II.F.2 - ANO-2 Inadequate Core Cooling (ICC) Implementation Letter
Dear Mr. Knighton:
Your October 24, 1986 letter (2CNA108609) which transmitted your safety evaluation of our ANO-2 ICC instrumentation system requested that we provide:
(1) The status of environmental qualification (EQ) testing of the in-containment cabling and connectors for the core exit thermocouple (CET) system, and (2) The implementation letter.
RESULTS OF EQ TESTING:
EQ testing of the in-containment cabling and connectors for the CET system has been completed.
The results of this testing indicate that the present cabling / connector configuration does not prevent moisture intrusion into the connectors.
The first LOCA simulation was begun on September 3, 1986.
This simulation was halted on September 5 due to the erratic behavior exhibited by the CET.
The LOCA chamber was opened and the cable assembly was removed for examination.
The connectors were found to be corroded inside indicating that moisture intrusion was occurring.
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MEMBER MIDDLE SOUTH UTiuTIES SYSTEM
Mr. G;arg3 W. Knight:n Janusry 2,1987 After the connectors were thoroughly cleaned and dried, the cable assembly was replaced in the LOCA chamber, and another LOCA simulation was begun.
This simulation was also halted after two days due to the CET's erratic behavior.
The cable assembly was removed from the LOCA chamber for measurements and inspection. Again, the connectors were found to be corroded.
Based on the EQ testing results described above, we conclude that the current configuration of the cable assembly does not paevent moisture intrusion into the connectors.
It is also concluded that the erratic behavior of the CET is attributable to leakage currents between the CET and the energized conductors along the moisture path (i.e., in the connector regions).
Since the conductors which carry the signals from the self powered neutron detectors (SPNDs) must be energized during an accident and since the influence of these leakage currents on the CET cannot be predicted, the output of the CET would be considered suspect.
AP&L has discontinued this test phase and is considering alternatives for providing an environmentally qualified CET in-containment cabling system.
This may entail modification of the existing system or replacement of some or all of the cabling and connectors. AP&L will inform you of the modifications / replacements to the CET in-containment cabling system.
As stated in our March 18, 1986 letter (2CAN038607), the earliest opportunity to install qualified connectors is the ANO-2 sixth refueling outage (2R6) which is currently scheduled to begin in January ]988.
In the interim, the qualified subcooling margin and vessel level monitors will be available for the monitoring of ICC.
IMPLEMENTATION LETTER:
This implementation letter report is formatted in accordance with Enclosure 3 of your October 24, 1986 letter (2CNA198609).
(1) Notification that the system installation, functional testing and calibration are complete and test results are available for inspection.
The majority of the ANO-2 ICC instrumentation was installed during the fifth refueling outage (2R5).
The one exception is the qualified in-containment cabling and connectors (see description above).
Functional testing and calibration of the installed portion of the ICC instrumentation are complete.
The test results and field data are available for your inspection.
(2) Summary of licensee conclusions based on test results, e.g.:
(a) the system performs in accordance with design expectations and within design error tolerances; or (b) description of deviations from design performance specifications and basis for concluding that the deviations are acceptable.
Mr. Gesrga W. Knighton JEnutry 2, 1987 After further review of the Oak. Ridge' test results and other Radcal data,.it has been' determined that the signal doubling time for a SLOW sensor.is-about 92 seconds.. The 18 second time given in the Final
' Design Description (FDD) (Table 6) was based on a Technology for Energy (TEC) report which is purely; theoretical..This change, in conjunction with recalculated worst-case I/O hardware delay-times, means that the-uncovered indication delay time ~for the TEC 601 display-is changed.from about 26 seconds to about 129 seconds for a SLOW sensor. The worst-case delay time for the SPDS display uncovery indication is about 160 seconds for the SLOW sensor.
It should be noted that the top sensor in the dome is a. FAST sensor.
The worst-case delay for the response of this sensor is 48 seconds at the TEC 601 display and 78 seconds at the SPDS.'
This sensor is important for early detection of ICC and its response time is
^
significant1y'less than the 2 minutes'given on page 6 of the SER.
l As a result of recalculation of response times, Table 6 and Figure 6 of 2
the FDD have been updated (See Attachments 1&2).
T j
'(3) Description of any deviations of the as-built system from previous j'
design descriptions with any appropriate explanation.
The following are deviations in the as-built ICC Monitoring System-from the FDD:
~(A) Section 4.3, paragraph 2 of the FD9 implies that;the SPDS has.
control capability over the data acquisition system (DAS). The SPDS was never intended to have control capability; it is for i
display only.
The-phrase "either display device" actually refers-j to the TEC 601 or the TEC VT-220 maintenance terminal.
(B) Pages 11 and 33 of the FDD refer to averages being stored.in trend t
. buffers in the TEC DAS.
It should be clarified that the only averages presently stored in.the TEC DAS are one-minute and
[
fifteen-minute heat transfer values for the incore sensors.
(C) -As noted on page 28 of the FDD, a new in-containment cable system was installed during 2R5. The TEC transient shield has been eliminated. The new system consists of three cable segments as described below:
1 (1) Extends from the Radcal Level Instrument (RLI) to the reactor i
head work platform.
The cable assembly is contained in a 3'
l sealed metal hose and has a TEC connector on one end and a i-VEAM-LITTON connector on the other end.
(2) Extends from the reactor head work platform to the top of the 1
maintenance structure.
The cable assembly is contained in a metal hose and has VEAM-LITTON connectors on both ends.
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Mr. G:crg2 W. Knighten J nutry 2, 1987 (3) Extends form the top of the maintenance structure to the containment penetration..The cable assembly is a hypalon jacket softline with a VEAM-LIT 10N connector on one end and pigtails on the other end.
All of the above assemblies are environmentally qualified.
(4) Request for modifications of Technical Specifications to include all ICC instrumentation for accident monitoring.
The ANO-2 ICC Monitoring System consists of three parts or subsystems
-(Subcooling Margin Monitors, CETs and Reactor Vessel Level Monitoring System (RVLMS)).
Each of these subsystems is integral to the operation of the ICC Monitoring System.
Therefore, since the installation of qualified in-containment cabling and connectors for the CETs was not possible during 2R5 and NRC approval of the plant-specific installation has not been received (see answer to (5) below), we wish to defer submittal of Technical Specifications covering ICC instrumentation as described in Enclosure 3 of your October 24, 1986 letter.
Instead, we intend to submit Technical Specifications covering all ICC instrumentation after the installation of qualified CET in-containment cabling and connectors (i.e., following 2R6 which is currently scheduled to begin in January 1988) and receipt of NRC approval of the plant-specific installation.
(5) Request for NRC approval of the plant-specific installation.
Although the installation of qualified in-containment cabling and connectors for the CET system was not possible during 2R5, the remainder of the ICC Monitoring System is in its final form.
Therefore, AP&L requests NRC approval of the plant-specific installation if NRC believes it is appropriate to review the plant-specific installation before qualified in-containment cabling and connectors are installed.
(6) Confirm that the E0Ps used for operator training will conform to the technical content of NRC approved E0P guidelines (generic or plant specific).
As we have not yet received NRC approval of our E0P technical guidelines, we cannot confirm that the E0P will conform to the l
technical content of NRC approved E0P guidelines.
However, in updating the E0P, we do intend to follow the E0P technical guidelines which we submitted to you in our April 15, 1986 letter (2CAN048608).
Very truly yours,
. Ted Enos, Manager Nuclear Engineering and Licensing JTE/MJS/sg Enclosures
ATTACHMENT 1
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SENSOR e SENSCR REGION DRAIN RATE ACTUAL SLOPE
.1AN0 METER-MANCM!iER
- AND T!PE LOCATION
.130iFT.BR UNCOV.
DEG.F./SEC.
OFFSET DELAY REF.TCC (FEET /SEC)
TIME (FEET)
(SEC.)
(FEET)
(SEC.)
'2 FAST 17.70 DOME 0.240 0.00 0.93
'd.280 1.167
~3 SLOW 13.30 D)ME 0.240 18.33 0.71 0.280 1.167 4 SLOW 10.20 PLENUM 0 240 31.25 0.71 0.420 1.750 5 3 LOW-8.10 FLENUM 0.240 40.00 0.71 0.420 1.750 6 FAST 4.00 PLENUM 0.011 530.00 0.93 0.420 38.182 7 FA?T 3.90 FLENUM 0.011 720.91 0.93 0.420 38.182 FOXBORD FOXBORO TEC I/O TEC I/O SCFTWARE SPDS SENSOR 601 INDICATED DELAY DELAY IELAY DILAY
' DELAY D13 PLAY DOUBLE UNC0VERY TIME (t!G.F.)
(SEC.)
(DEG.F.)
(SEC.)
(SEC.)
DELAY TIME (SEC.)
(SEC.)
(SEC.)
17.50 18.82 17.50 18 82 1.00 30.00 19.00 47.78 17.50 24.65 17.50 24.65 1.00 30.00 92.00 147.36 17.50 24.65 -
17.50 24.65 1.00 30.00 92.00 160.86 17.50 24.65 17.50 24.65 1.00 30.00 92.00 169.61 17.50 18.82 17.50 18.82 1.00 30.00 19.00 614.79 17.50 18.82 17.50 18.82 1.00 30.00 19 00 805.70 SPDS INDIC.
ACTUAL LEV.
ACTUAL LEV.
601 UFC0VERY SPDS UNC0VERY UNCOV. TIME AT 601 TIME AT SPDS TIME UNCERTAINTY UNCERTAINTY (SEC)
REF. TOC.
REF. TOC (FEET)
(FEET)
(FEET)
(FEET) 77.73 6.23 6.00 11.47
-11.70 177.36 6.00 6.00
-7.30
-7.30 190.86 6.00 6.00
-4.20 4.20 199.61 6.00 6.00
-2.10
-2.10 644.79 5.07 4.74
-0.93
-1 26 835.70 2.97 2.64
-0.93
-1.26
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1 h
".1 SQ.FT. BREAK LOCA" E5s 20 W
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l NOTE: SPDS AND LOCAL LEVEL I
INDICATION GIVE ONLY THE 10 -
q DISCRETE VALUES SHOWN BY 17 -
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LEVEL INFO. IS AVAILABLE.
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TIME (SECONDS) 1 4