ML20217M651

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Engineering Evaluation Hrrm Coaxial Cable LOCA Test Post- Test Insulation Resistance Results
ML20217M651
Person / Time
Site: San Onofre  Southern California Edison icon.png
Issue date: 01/23/1996
From: Stilwagen S, Trotta K
SOUTHERN CALIFORNIA EDISON CO.
To:
Shared Package
ML20217M648 List:
References
NUDOCS 9708250128
Download: ML20217M651 (26)
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{{#Wiki_filter:- = h h hb Page 1 of16 4 a ENGINEERING EVALUATION i High Range Radiation Monitoring (HRRM) Coaxial Cable LOCA Test Post Test Insulation Resistance Results SAN ONOFRE NUCLEAR GENERATING STATION UNITS 2 & 3 1 / / 23! 4 4 Prepared By: Date: / en Trotta ~ K !'M ! M Date: D Reviewed By: Steve Stilwagen V 4c 4% e M ~ 9708250128 970820 PDR ADOCK 05000361 P PDR

Page 2 of16 TABLE OF CONTENTS SECTION TITLE PAGE 1.0 SUBJECT 3 2.0' REFERENCES 3 3.0 PROBLEM DESCRIPTION 3

4.0 CONCLUSION

3 5.0 EVALUATION 4 6.0 RECOMMENDED ACTION 6 TABLES 1 Test Specimen Descriptions 8 2 Shon Penetration - Conductor to Shield IR Test - Dry Condition 9 3 Shon Penetration - Conductor to Shield IR Test - Wet Condition 10 4 Short Penetration - Shield to Ground IR Test 5 Long Penetration - Shield to Ground IR Test l '. 6-Mandrel-Shield to Ground IR Test 13 7 Conduit Penetration - Shield to Ground IR Test 34 FIGURES 1 Electrical Test Schematic 15 2 Improved Test Vessel Penetration Design 16

3 Page 3 of16 1.0 SUBJECT 'I e purpose of this engintering evaluation is to investigate and document the failure analysis of the LOCA test specimens and test vessel penetrations for the HRRM coaxial cable LOCA simulation as identified in Reference 2.1.

2.0 REFERENCES

2.1 SCE Document " Coaxial Cable LOCA Simulation Procedure for Monitoring Test Specimen Electrical Parameters." Dated Jaanary 12,1996 2.2 SCE Document " Coaxial Cable LOCA Sin u!ation Test Results." Dated January 18,1996 2.3 Commerial Grade Item Dedication Test Lab Report 96 2978 3.0 PROBLEM DESCRIPTION The results of the coaxial cable LOCA simu!ation test, as documented in Referen ;c 2.2, indicate the test program failed to meet the intended ob.iectives. It was uncertain whether the failure was due to the test setup (test vessel cable penetration) or the test specimens themselves. This evaluation will investigate and determine whether the test program failure was due to the test specimens, or the test setup.

4.0 CONCLUSION

The overall conclusion is that failure of the "short" test penetration strongly contributed to the test program failure. The contribution came in the form oflow insulation resistance between shield to ground and conductor to shield within the penetration, affecting the eatire circuit. This is evidenced by the low conductor to shield IR measurements taken immediately after the LOCA simulation (Reference 2.1, Table 6), and the shield to ground measurements taken 20 uays later. 4.1 Cable Specimens The Brand Rex cables are considered to have failed the LOCA test, with shield to ground insulation resistance measurements below acceptable levels. The Brand Rex cablejacket does not provide adequate insulation resistance as evidenced by it grounding to the mandrel, in addition to the lowIR measurements at the test vessel penetrations. This grounding may have greatly contributed to the erratic behavior of these cables during the LOCA simulation. The Braid Rex cable test vessel penetrations had low conductor to shield (E7 to E8 ohms) and shield to gcound + (E8 to E9 ohms) IR. These measurements were taken in the dry condition, and it is expected that during the steam test these measurements would be decaces lower.

Page 4 of16 The Rockbestos coaxial cable provided acceptable conductor to shield and shield to ground IR as esidenced by the high measurements (E12 ohms), with two notable exceptions. The 250' RSS-6 105/LE specimen at the "short" penetration showed low (E8 ohms) shield to ground IR, and was seen to be dripping water during the " wet" conductor to shield test. This indicates physical damage to the cablejacket inside the epoxy penetration. The 90' RSS 6-105/LE specimen also exhibited low conductor to shield IR (lE8 ohms)in the short penetration. 4.2 Test Vessel Penetrations The "short" test vessel penetration showed visual damage to the epoxy potting, and there was evidence ofmoisture intrusion through the 250' Rockbestos RSS-6-105/LE cablejacket. Damage to the penetration was also evidenced by extremely low conductor to ground IR measurements taken the morning after the LOCA test. This indicates the penetration assembly had experienced the negative effects of moisture (steam) intrusion. These measurements we.e taken in the dry condition, and it is expected that during the steam test these measurements would be decades lower. 5.0 EVALUATION The " post mortem" evaluation of the test vessel penetration and mandrel was performed by measuring the IR of the various test specimens and test s ssel penetrations. Insulation Resistance (IR) Measurements Two types ofIR measurements were made: 1) center conductor to shield and; 2) shield to ground. The center conductor to shield measurement provides a measure of the ability of cable insulation to insulate the center conductor. The shield to ground IR measurement provides a measure of the cablejacket to insulate the cable shield from ground. When reviewing the information below, consider that new cables would be expected to exhibit a minimum IR readings on the order of E12 ohms. For the purpose of this evalut tion, the test specimens and vessel penetrations were divided into four groups (see Table 1 and Figure 1 for specimen descriptions): 1. Short penetration. This is the test vessel penetration that contains the "short" five foot pigtails exiting the chamber. The pigtails were left hanging in air, and were not connected to any test measuring equipment. This penetration contains the pigtails of test specimens two through seven. 2. Long Penetration. The test vessel penetration that contains the "long" 25 foot pigtails that were connected to the test ir maentation. This penetration contains the pigtails of specimens two through seve - 3. Mandrel. The test mandrel c taining the individual test specimens (two through seven).

Page 5 of16 4. Conduit Penetration. The test vessel penetration that contains both the unconnected five foot pigtail and 25 foot pigtail connected to the test equipment for the inside conduit cable specimen (specimen 1). Note: Specimen 8 was used only to monitor cable temperature and not signal characteristics. 5.1 Short Penetration Dry and Wet Conditions - Center Conductor to Shield From the post LOCA test measurements taken of all specimens immediately following steam testing, the short penetration exhibited the lowest (worst) IR readings. Only this specimen was tested again both dry and wet as shown in Tables 2 and 3. To summarize the results, the Brand Rex cables exhibited the lowest readings (E7 to E8 ohms), while the Rockbestos cables were generally very high (E8 to E14 ohms). The penetration was wetted by holding it vertically upright in a vise, and standing water (about % cup) was applied to the intemal portion of the penetration. In the wet condition, the IR values were similar to the dry condition. Since the penetration was only soaked for 10 minutes in room temperature tap water, and did not experience the high temperature and pressure steam as during the LOCA test, IR was not expected to be significantly affected by this wet test. It should be noted the Rockbestos 250' RSS 6-105/LE test specimen was seen to be dripping water, coming from inside the cablejacket. See the shield to ground IR measurements discussed below. 5.2 All Groups - Dry Condition Shield to Ground o The shield to ground measurement provides an insight into how well the shield will perform as a 4 " drain." If grounded at only one end, the shield properly acts to draw off any extraneous signals. If grounded at more than one point, the shield itself may act as source of signal noise. 5.2.1 Short Penetration: See Table 4. All specimens exhibited acceptable IR measurements (E8 to E12 ohms). The lowest readings were for the Brand Rex. cables (E8 ohms), while of the Rockbestos cables, only the 250' RSS-6-105/LE had a reading below E12 ohms. This is the same cable that was seen to drip water during the wet condition conductor to shield IR test discussed above, indicating cablejacket damage. 5.2.2 Long Penetration: See Table 5. All specimens exhibited acceptable IR measurements. The lowest readings were for the Brand Rex cables (E8 ohms), while the Rockbestos readings were on the order of E12 ohms.

5.2.3 Mandrel

See Table 6. All Rockbestos specimens exhibited reading on the order of E12 ohms. The Brand Rex specimens were grounded to the mandrel. This indicates thejacket provided no insulating

Page 6 of16 function. 5.2.4 Conduit Penetration: See Table 7. The specimen exhibited readings on the order ofE12 ohms. 5.3 X-ray Investigation of Short Penetration Since the test vessel cables are encased in epoxy filled two inch diameter schedule 60 iron piping. x rays did not reveal the cable configuration within the pipe. It was decided that to cut the pipe open to reveal the epoxy and cables would most likely have damaged the cables, making any further x-rays inconclusive. 5.4 Discussion of Rockbestc.s RSS-6-104/LE 1992 Cable Jacket Blistering The cable jacket of the Rockbesto s RSS-6-104/LE 1992 (specimen 2) had large blisters, or bubbles, approximately 40 total, aver its 90' length. The large blisters were approximately three times the cable diameter. Although visually a problem, it did not affect the cable performance. Since shield to ground resistance remained high (2.5 E12 ohms), thejacket blisters are not considered an insulating problem. Interestingly, the 1994 version of this cable (specimen 5) showed no signs of blistering or bubbles. Samples of the 1992 and 1994 cables were sent to Rockbestos for further analysis. The 1992 version of this cable was installed on the inside containment portion of the Unit 2 HRRM system (2RE7820-1 and -2) Since the cablejacket maintained an extremely high shield to ground resistance, the Unit 2 applicatic n is considered acceptable. 5.5 Test Monitoring Equipment Calibration The responsibility for test monitoring equipment used during the LOCA test belongs to Wyle Laboratories. It should be noted that in a post LOCA calibration check, some of the monitoring equipment was found to be slightly out of tolerance. These calibration problems will be addressed as an anomaly in the Wyle test report. For the purposes of this test program the minor accuracy problems do.not change the conclusions or recommendations of this evaluation. Test monitoring equipment used in this evaluation is the responsibility of SCE and is identified on the individual Tables and Reference 2.5 as appropriate. 6.0 RECOMMENDED ACTIONS f 6.1 Brand Rex Cable Failurc I The failure of the Brand Rex cable jacket to provide shield to ground electrical insulation indicates that applications of this cable may experience excessive noise during steam line break conditions. It is recommended that any EQ applications of this cable be reviewed to see if this an acceptable condition dur ng post-accident operation. i

Page 7 of16 6.2 Rockbestos Cable The primary objective of the LOCA test was to quantify the maximum induced current from steam ;ine break environmental conditions and confirm that the installed cable will properly function during accident conditions. All cables exhibited induced currents due to the steam line break conditions. As discussed in Reference 2.2, only the first 1,000 seconds of testing provided useful information. After that time the signals became e ratic, indicating some type of cable failure. However, the LOCA testing has confirmed that there will be some induced cur.cnt, but does not provide a clear picture of the expected magnitude or duration of the phenomen ' i. Any future testing should incorporate the following concerns: 6.2.1 Test Vessel Cable Penetration Design 4 Since the signals being measured were so small, low shield to ground insulation resistance in the "short" penetration may have greatly contributed to the erratic test monito ing data. An improved test vessel penetration should be designed to eliminate any concern that localized submergence or steam intmsion may have contributed to the erratic signal problem. See Figure 2 for a simplified schematic of a proposed test vessel penetration. In this design, the test specimeas are connected by MHV connectors to Teflon lead wires, physically separated within an epoxy filled pipe by a spinning wheel type arrangement. The MHV connectors are located inside the test chamber are covered in LOCA qualified Raychem heat shrink tubing. 6.2.2. Test Speciraens 1 It is unnecessary to search for a relationship between cable length and induced signal strength if the tested configuration is representative of the installed condition. The test specimens should consist of the following: One 250' specimen of Rockbestos RSS-6-104/LE couial cable with 125'in simulated conduit and 125'in simulated cable tray. This would be representative of the avaerage instilled configuration. No cable mandrel should be used. The cable should be routed in a manner not too exceed the cable minimum bend radius. One 250' specimen of Rockbestos RSS-6-105/LE coaxial cable in simulated conduit. This would be representative of a future installation of all low noise cable routed completely within conduit. The test specimens should be tested with a small current (IE-11 amps) to simulate the HRRM detector keep alive source. The current source should be variable in case it becomes necessary to increase the signal current to search for a strength that is greater than any signal produced by triboelectric or piezoelectric affects. Fut"re testing should use unaged cable, since this would represent the worst case in terms of the generation of triboelectric effects. Thermal cycling of coaxial cable is known to " relax" the cable, lessening the effects of shield and insulation movement. \\

4 4 +4 Page 8 of16 6.3 Revise Unit 2 And 3 Emergency Operating (EOI) Procedures Determine where radiation monitors 2(3)RE7820-1 and -2 ag e cited it. the Emergency Operating Instructions. These instructions should be revised to include a caution that these instmments may exhibit a transient spurious signal during an inside containment high energy line break environmental conditions indicating a high containment radiation condition. The high radiation conditions should be verified against other radiation monitors, i 1 4 4

I Page 9 ofl6 i Table 1 Test Specimen Descriptions Specimen Description Nunber 1 30' Rockbestos RSS-6-105/LE coaxial cable in conduit fixture. 2 90' Rockbestos RSS-6-105/LE coaxial cable 3 250' Rockbestos RSS-6-105/LE coaxial cable 4 90' Rockbestos RSS-6-104/LE coaxial cable 5 196' Rockbestos RSS-6-104/LE coaxial cable 6 90' BrruidR-x CS 75146 coaxial cable 7 250' BrandRex CS 75146 coaxial cable 8 20' Rockbestos RSS-6-105/LE coaxial cr.ble

Page 10 of16 TABLE 2 INSULATION RESISTANCE TEST CENTER CONDUCTOR TO SHIELD SHORT PENETRATION - DRY CONDITION Specimen Resistance Acceptance Time /Date 0500VDC Criteria pjp Number 1 NOTE 2 N/A >10' Ohms N/A 2 1/8/96 1.5E8 >10' Ohms P 9:10AM NOTE 3 3 1/8/96 1E14 >10' Ohms P 9:10AM 4 1/8/96 1E14 >10' Ohms P l 9:10AM S 1/8/96 1E14 >10' Ohms P 9:10AM 6 1/8/96 1.5E8 >10' Ohms P 9:10AM 7 1/8/96 1.2E7 >10' Ohms F 9:10AM 8 N te 1 N/A N/A N/A Notes: 1. This test specimen is the 20' of Rockbestos RSS-6-105/LE used to monitor cable surface and center conductor temperature only. 2. Not included in this test. 3. Unstable reading. Test Measuring Equipment Calibration: ID# Il-6044 cal 11/14/95 due 05/14/96 by SCE MET 28

l i Page 11 ofl6 i TABLE 3 l STATIC INSULATION RESISTANCE TEST CENTER CONDUCTOR TO SHIELD SHORT PENETRATION - WET CONDITION (NOTE 4) Specimen Resistance Acceptance Number TimeIDate @500VDC Criteria p/p 1 NOTE 2 N/A >10' Ohms N/A 2 1/8/96 4E8 >10' Ohms P 9:25AM 3 1/8/96 7E13 >10' Ohms P 9:25AM NOTE 3 4 1/8/96 1E14 >2 0' Ohms P 9:25AM 5 1/8/96 1E14 >10' Ohms P 9:25AM 6 1/8/96 1.5E8 >10' Ohms P 9:25AM 7 1/8/96 2E7 >10' Ohms F 9:25AM 8 Note 1 N/A N/A N/A Notes: 1. This test specimen is the 20' of Rockbestos RSS-6-105/LE used to monitor cable surface and center conductor temperature only. 2. Not included in this test. 3. This specimen is dripping water through cable (not on outside). 4. The penetration was held upright in a vise, and standing water (about cup) was applied to the internal portion of the penetration. Test Measuring Equipment Calibration: ID# Il-6044 cal 11/14/95 due 05/14/96 by SCE MET 28

Page 12 of16 FIGURE 4 TABLE 4 INSULATION RESISTANCE TEST SHIELD TO GROUND-SHORT PENETRATION Multi-Specimen Resistance Acceptance Number me/Date 9500VDC Criteria 1-NOTE 2 N/A >10' Ohms N/A -2 1/10/96 2E12 >10' Ohms >200M-SAM Ohm 3 1/10/96 2E8 >10' Ohms >200M 8A'! Ohm 4 1/10/96 1E12 >10' Ohms >200M 8AM Ohm 5 1/10/96 2E12 >10' Ohms >67M-8AM Ohm 6 1/10/96 2.5E9 >10' Ohms >200M 8AM Ohm 7 1/10/96 3E9 >10' Ohms >200M 8AM Ohm 8 Note 1 N/A N/A N/A- ~ Notes:L 1. This test ~ specimen is the~20' of Rockbestos RSS-6-105/LE used to-monitor cable surface and center conductor ' temperature only. -2. Conduit penetration tested separately.- Test Measuring Equipment identified in Reference 2.3.

Page 13 of16 TABLE 5 STATIC INSULATION RESISTANCE TEST SHIELD TO GROUND LONG PENETRATION 4 l Specimen Resistance Acceptance Multi-Number Time /Date 9500VDC Criteria M*h"# 1 NOTE 2 N/A >10' Ohms N/A 2 1/10/96 1E12 >10' Ohms >200M 8:15AM Ohms 3 1/10/96 1E12 >10' Ohns >200M 8:15AM Ohms 4 1/10/96 2E12 ->10' Ohms >200M 8:15AM Chms 5 1/10/96 1E12 >10' Ohms >200M 8:15AM Ohms 6 1/10/96 4E8 >10' Ohms >200M 8:15AM Ohms 7 1/10/96 3E8 >10' Ohms >200M 8:15AM Ohms 8 Note 1 N/A N/A N/A Notes:

1. -

This test specimen is the 20' of Rockbestos RSS-6-105/LE used to monitor cable surface and center conductor temperature only. 2. Conduit tested separately. Test Measuring Equipment identified.in Reference 2.3. 1

1 s Page 14 of16 1 a y TABLE 6 INSULATION RESISTANCE TEST SHIELD TO GROUND MANDREL Multi-Specimen Resistance Acceptance Time /Date Number 9500VDC Criteria 1 NOTE 2 N/A >10' Ohms N/A 2 1/10/96 >3E12 >10' Ohms >200M 7:45AM Ohms 1 j 3 1/10/96 >3E12 >10' Ohms >200M 7:45AM Ohms 4 4 1/10/96 1E12 >10' Ohms >200M 7:45AM Ohms i 5 1/10/96 2.5E12 >10' Ohms >200M 7:45AM Ohms 6 1/10/96 Grounded >10' Ohms >200M 7: JSAM Ohms 7 1/10/96 Grounded >10' Ohms 15M 7:45AM Ohms 8 Note 1 N/A N/A N/A Notes: 5 1. This test specimen is the 20' of Rockbestos RSS-6-105/LE used to monitor cable surface and center conductor temperature only. Test Measuring Equipment identified in Reference 2.3. e-4 4 4 4 1 T e,-

Page 15 of16 TABLE 7 STATIC INSULATION RESISTANCE TEST SHIELD TO GROUND CONDUIT PENETRATION Multi-specimen Resistance Acceptance Number Time /Date $500VDC Criteria Meter (3V) 1 1/10/96 1.5E12 >10' ' Ohms >200M Short LenJ B125AM Ohm i 1/10/96 2E12 >10' Ohms >200M T,ong Lead 8 25AM Ohm 3 N/A N/A, >10' Ohms N/A 4 N/A ,jfA >10' ohms N/A 5 N/A N/tt > 1 0' O h gts N/A 6 N/A N/A >10' Ohms N/A 7 N/A N/A >10' chas N/A -8 Note 1 N/A N/A N/A Notos: - - 1. Thie-test specimen 10 the 20' of Rockbestos RSS-6-105/LE used to monitor-cable surface and center conductor temperature only. Test Measuring Equipment identified in' Reference 2.3.- lL

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fbfh ~ COAXIAL CABLE LOCA SIMULATION TEST RESULTS Page 1 of 7 1 ~ General These tests were originally planned to include LOCA and Main Steam Line break simulated accidents. After completion of the first LOCA test, it became apparent that each of the cables had suffered some loss of integrity. This was determined through significant changes in electrical resistance properties. 1 Continuation of the testing was abandoned. The objectives of the testing were to:

a. Quantify the maximum values of induced current in the cebles from rapid changes in temperature.
b. Determine if the charge induced was a funcCon of the cable length, i
c. Confirm that the Rockbestos cable installed within the containment will withstand LOCA and Main Steam Line breaks without loss of function.
d. Determine thermal delay and effects on maximum induced currents of cable in condult.
2. Induced Current Measurements The application of steam into the autoclave produced initial positive increases in current in each Rockbestos cable. The Brand Rex cables produced negative changes in current. The negative polarity current was different from previous tests performed with hot air haat guns or in a hot air test chamber. The data obtained from the Brand-Rex cables was considered suspect. Evidence of moisture dripping out of the connector ends during the test, confirmed the loss of Jacket integrity. The initial current values indicate that the Jacket boundary of the Brand Rex cables were probably penetrated during the first steam application.

Graph 1 shows the induced currents measured from the Rockbestos cables during the first 1000 seconds of steam application. The maximum values above 4 1 x 10 amps have been fitted. The initial range of the picommmeter was set at

  • 5 x 104 amps and readable to about 20% over range or 6 x 104 amps. The general shape of the fitted data was determined by observations of previous tests performed by General Atomic Company and from heat gun and oven tests run at SCE facilities.

The projected maximum value from all cables given in graph 2 is 2.0 x 10 amps 4 or 2000 R/hr equivalent dose. Slowly applied, dry heat chamber test results, in comparison, produced an average of 125 R/hr equivalent induced current for 100 ft of cable. Refer to table i for maximum induced current values. GC Me vt V

1 J COAXIAL CABLE LOCA SIMULATION TEST RESULTS Page 2 of 7 Wyle Test Data 12/14/96

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COAXtAL CABLE LOCA SIMULATION TEST RESULTS Page 3 of 7 W M Aut a i mperature 360 - /~ p -x; 300 / ts00 5, .s.kj.g f60 S-; 100 i fE f IE0 f fE! fE3 Graph 3 Autoclave temperature vs. Time Table 1 Maximum Induced Currents Cable No. Length Max. Current Equivalent in feet in amps Dose in R/hr Rockbestos RSS-6-104/LE 90' 2.1 x 104 2100 Rockbestos RSS-6-104/LE 196' 1.3 x 104 1300 Rockbestos RSS-6-105/LE 90' 1.2 x 104 1200 Rockbestos RSS-6-105/LE 250' 2.0 x 104 2000 RSS-6-105/LE in conduit 25' 2.2 x 104 220

3. Charge vs. Cable Length Referring to table 1, there does not appear to be a measurable relationship -

between induced current and the length of the cable. The Rockbestos RSS 105 type cable data reasonably fits the theory that the current is proportional to the length. However, the Rockbestos 104 cable current measurements seem in

COAXIAL CABLE LOCA SIMULATION TEST RESULT $ Page 4 of 7 direct conflict. Post test examination took place to see if these cables could have been inadvertently switched. There was no evidence to suggest that a switch had taken place. Ratios of the collected induced current data over the first 100 seconds of the test were averaged. The ratio of Rockbestos 105 cable currents from 250 ft to 90 ft was 2.3 to 1. The ratio of Rockbestos 104 cable currents from 196 ft to 90 ft was 0.72. If the 104 cables had been reversed. then the ratio would have been 2.1 to 1. Post test observations showed that the 196' Rockbestos cabling had blistered during the test. Further examination revealed that this cable was manufactured in 1992 and the non blistered 90' piece was manufactured in 1994.

4. Steam Withstand CappHity As the test progre6 4. c ) parent large currents where flowing in the cables during the testing w any large noise spikes with generally erratic outputs.

This behavlor was sli. Or to those experienced during the Sandia, some of the earlier General Atomic testing and tests performed at SCE facilities. The Sandia post accident insulation resistance (IR) measurements showod values well below expected IR values for any temperatures within the tested range. Further examination showed that splits had developed in the jackets. Molsture migrating into the cable dielectric caused these low and erratic readings. A series of IR values were taken after the applied steam test. All values were below expected values. After overnight cooling of the autoclave, the bulk of the cable wound on the mandrel was cut from each of the epoxy potted, penetrat!ons. The bulk cable on the mandrel produced IR values are shown in table 2. Values for each of the penetrations were also measured separately. l These values are also given in table 2.

COAXlAL CABLE LOCA SIMULATION TEST RESULTS Page 5 of 7 Table 2 IR Cable Values Cable No. Total assy Main cable Penetration Penetration (132.6'F cool (mandrel) (short length) (Long length) down) ambient temp ambient temp ambient temp Insulation Resistance in Ohms (Center conductor to shield) RSS 6-104196' 5.0 x 102 3.9 x 10 1.3 x 10 7.3 x 10 5 RSS-6-104 90' 2.0 x 10'_ 4.0 x 10 3.2 x 10" 5.5 x 10 RSS-6105 250' 2.0 x 10' 3.5 x 10 1.8 x 10' 5.6 x 10 RSS-6-105 90' 1.6 x 10' 6.5 x 10 2.5 x 10' 5.7 x 10" i RSS-6105 25' 4.5 x 10 2.5 x 10" 2.1 x 10 5.4 x 10'0 7 7 conduit Brand Rex 90' 2.1 x 105 1.3 x 10" 3.5 x 10' 6.8 x 10 Brand Rex 250' 2.9 x 10s 2.5 x 101 5 5 2.5 x 10 1.1 x 10 The total assembly IR values were taken with moisture stillin the autoclave. The sectioned values were taken the following morning. The cables were dry because the residual heat within the autoclavo had vaporized the remaining water which was free to escape. With the exception of the RSS-6-104 90' cable, all cables showed lower than expected IR values in the short penetration assembly. The conduited cable used separate penetration assemblies. The short conduit penetration section also produced low IR values. The failed cabling with IR values below 1.0 x 10' ohms can be attributed to a faulty penetration assembly. The RSS-6-104 90' cable marginally passed in a wet environment at 132.6 'F but estimates of the complete cable system the next morning, after drying out, would have been a decade higher (Adding three values in parallel = ~2.0 x 10' ohms). The Brand Rex 250 ft cable assembly failed at each penetration. The ability of each cable to survive and function during and after a LOCA or Main Steam Line break has not been conclusively shown. However, the opposite has not been demonstrated either i.e. the cable failed during the test. The IR evidence implicates the short penetration assembly as failing.

COAXIAL CABLE LOCA SIMULATION TEST RESULTS Page 6 of 7 l

5. Conduit influence on Cable Currents Peak induced current values were delayed from about 30 seconds after the test l

began for bare cables to 60 seconds after the test for the conduit cable. This l delay value differs from the projected delay of 3 minutes. Failures after 1 hour I and twenty minutes at each of the bare cable penetrations provented a long term assessment of the usefulness of the conduit. The current had been steady and of low value during this initial period.

6. Conclusions The tests were limited to a LOCA simulation only. The cabling assembly failed during the test. The IR measurements show that the cabling in at least one of the penetration sections failed. Penetrations similar to those used in this test

- are not used within the plant for coaxial cabling. The results are inconclusive as to whether the bulk of the cabling survived this LOCA test. It is possible that the cables failed but recovered during the cool down process overnight, allowing the moisture to escape and obtaining acceptable IR readings. Peak induced currents of 2.1 x 104 amps or 2. l x 10' R/hr equivalent were produced during these tests. Projections for induced current based on testing performed at SONGS facilities for 250 feet of cable was 1.175 x 10' R/hr The maximum equivalent dose rate was underestimated by approximately a factor of 2. Measurements did not support induced current as a function of cable length. If the Rockbestos 104 cabling was switched, then there would be strong evidence to support projecting expected currents based on cable length. The results are inconclusive on this issue. The conduit test shows that the induced current generated in the conduit cable assembly was delayed by approximately 30 seconds compared with the bare cables. Since the induced current cannot be assumed proportional to the cable length, based on these tests, then we cannot draw any conclusions as to the estimated peak induced current in a 250 foot conduited cable. The 25 foot section tested produced peak curants of 2.2 x 10 amps or 220 R/hr. 4 If the current is subsequently found to be proportional to cable length, then the estimated current in a 250 foot conduited cable would be 2.2 x 10' R/hr. This value is approximately the same as that measured in bare cables.

COAXIAL CABLE LOCA SIMULATION TEST RESULTS Page 7 of 7 The data from this test showed conflicting time responses to the application of steam heat. One set of cables (Rockbestos 105) returned to close to the starting values within 100 seconds, The other set of cables (Rockbestes 104) took 350 to 450 seconds to get below a 100 R/hr and after 24 minutes were still above or close to 10 R/hr. G. Recommeridations i Before considering any further tests, a thorough examination of the failed penetration sections should be conducted. Alternate methods of sealing or feed through mechanisms should be used. Further tests are required to establish the relationship between induced current 4 i and cable length. This knowledge willinfluence the option of conduited cable, if a peak value of 2 x 10'is considernd unacceptable, A fully conduited cable specimen should be included in any future test!rg with a cable length as long as practically possible. Prepared By: MN Date: Y24 / /* 7 Tony" Hyde N5!f4 Reviewed By: ne Date: Dennis Beauchaine

June 4,1996 RECEIVED CDM MEMORANDUM FOR FILE JUN - ti 1996 RECORDS PROCESSING SUDJECT: liigh Range Radiation hionitoring (HRRhi) Coaxial Cable Engineering Analysis; Conclusions and Recommendations

REFERENCE:

1) NCR 951100073 2) Wyle Laboratories P.O. 6A2N5009 This inemorandum serves to summarize and distribute the attached engineering analysis. The analysis was performed to detennine the transient effects of high temperature and pressure 1 conditions (such as Main Steam Line Break (MSLB) or Loss of Coolant Accident (LOCA)) on the coaxial signal cable used with the High Range Radiation Monitor (HRRhi). The attached analysis concludes that when operating at the HRRM detector " keep alive" source signal strength equivalent to approximately 1 R/hr, thermally induced currents generated from the coaxkl signal cable will produce misleading radiation dose rate information following MSLB or LOCA. The coaxial signal cable current is generated by a phenomenon known as Thermally Stimulated Depolarization (TSD) of the dielectric. The duration of the thermally induced signals are expected to be approximately 15 minutes, with a resulting peak indication in the low. thousands of R/hr. If significant radiation dose tates do exist, the HRRM detector will generate a signal current that will be additive to the coaxial cable thermally induced current. Other conclusions are: The SONGS 2&3 installed HRRM signal cable design configuration of Rockbestos RSS. 6104/LE routed approximately one halfin conduit and one halfin tray is an acceptable condition and does not require a design change. Operator training initiated under disposition step 2 ofNCR 9$1100073 should include the + most recent technical information as summarized in Section 2A and detailed in Section 7.0 of the attached analysis. Operations should also review this information for any impact on the Emergency Operating Instructions. The problem of thermally induced currents is common to all HRRM systems operating + with signals in the pico ampere operating range. Southem California Edison will seek . industry participation in any funher investigations into this issue. The attached engineering analysis provides details regarding each of these conclusions. If you have any questions please call Ken Trotta at 89170 or myself at 87028. OhY'bbrL Conklin }& Attachment-

ec: K. Johnson J. Rainsberry J. Vandenbroek i J. Darling YX K. Trotta R. Wise T. Hyde i S. Stilwagen J. Beebe D. Beaucha!ne R. Greene M. Jones R, Waldo A. Thiel J. D ald CDM 1 l I i 1 ____}}

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