ML20117H556
| ML20117H556 | |
| Person / Time | |
|---|---|
| Site: | Wolf Creek, Callaway, 05000000 |
| Issue date: | 05/09/1985 |
| From: | Petrick N STANDARDIZED NUCLEAR UNIT POWER PLANT SYSTEM |
| To: | Harold Denton Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML19269B510 | List: |
| References | |
| SLNRC-85-14, NUDOCS 8505140331 | |
| Download: ML20117H556 (12) | |
Text
er e
SNUPPS Standardized Nuclear Urit Power Plant System 5 choke cherry Road Nicholas A. Petrick R vi land 20850 Executive Director May 9, 1985 SLNRC 85-14 FILE: 0278 SUBJ:
Equipment Qualification Justifications for Interim Operation (JIO)
Mr. Harold R. Denton, Director Office of Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission Washington, D. C.
20555 Dockets No: STN 50-482 and STN 50-483
Reference:
SLNRC 84-0135, dated December 21, 1984:
Same Subject
Dear Mr. Denton:
Enclosed are revised pages to be inserted in the Justification for Interim Operation (JIO) submitted by the reference letter. This revi-sion was necessitated by recent events during qualification testing of the splices used with the new-style Reference Junction Box (RJB) in the incore thermocouple circuits. At tte present time, the new-style RJB is used only at Wolf Creek Generating Station Unit No.1. Callaway Plant Unit No. I has the old-style RJB which is separately discussed in the reference letter.
The enclosure contains both proprietary and non-proprietary versions of the revised pages to be consistent with the JIO submitted by the ref-erence letter.
Ver truly yours, 8505140331gggg882 ADOCK A thT\\cQ gDR PDR Nicholas A. Petrick MHF/nld19a15 Attachment cc:
G. L. K'oester KGE B. Little USNRC/ CAL J. M. Evans KCPL G. C. Wright USNRC/RIII D. F. Schnell UE D. R. Hunter USNRC/RIV H. Bundy USNRC/WC I
Of f(, R 4'
+
i.g
, g p..<
SNUPPS Standardised Nucieer Unit Power Mont System 5 Choke Cherry Road Nicholas A. Petrick land 20e50 Executive Director May 9, 1985 SLNRC.85-14 FILE: 0278 SUBJ:
Equipment Qualification Justifications for Interim Operation (JIO)
Mr. Harold R. Denton, Director Office of Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission Washington, D. C.
20555 Dockets No: STN 50-482 and STN 50-483 s
Reference:
,SLNRC 84-0135,. dated December 21, 1984: Same Subject s
Dear Mr. Denton:
Enclosed are revised pages to be inserted in the Justification for Interim Operation (JIO) submitted by the reference letter.
This revi-sion was necessitated by recent events during qualification testing of the splices used with the new-style Reference Junction Box (RJB) in the incore thermocouple circuits. At the present time, the new-style RJB is used only at Wolf Creek Generating Station Unit No.1. Callaway Plant Unit No. I has the old-style RJB which is separately discussed in the,
reference letter.
The enclosure contains both proprietary and non-proprietary versions of the revised pages to be consistent with the JIO submitted by the ref-erence letter.
Ver,truly yours, t.h< \\c w
Nicholas A. Petrick MHF/nld19al5 Attachment cc:
G. L. Koester KGE B. Little USNRC/ CAL J. M. Evans KCPL G. C. Wright
~USNRC/RIII D. F. Schnell UE D. R. Hunter USNRC/RIV H. Bundy USNRC/WC 48dd g
[
- Mc &< pY e19 YY$'!0 4
or r
Enclosure Instructions for Inserting Revised Pages Into Interim Justification Position ESE-43 and ESE-44 A.
Westinghouse Proprietary Class 2 version:
Remove Insert Page 4 Page 4, Rev. 5/85 Page 5 Page 5, Rev. 5/85 Page 8, Rev. 5/85 B.
Westinghouse Class 3 version:
Remove Insert Page 4 Page 4, Rev. 5/85 Page 5 Page 5, Rev. 5/85 Page 8, Rev. 5/85
1.
WESTINGHOUSE CLASS 3 SNUPPS-Interim Justification Position for the Seismic and Environmental Qualification of the Incore Thermocouples, Connectors, Adaptors and Reference Junction Box (ESE-43 and ESE-44) h
+
4 W
?-
u'-ap
-g
---o-y---w ee Tw%g-em 1
f'mrk,-
q
- ee T'w-
- y*
-F-f--7MGrt--
1'-*--
WESTINGHOUSE CLASS 3 The Class 1E thermocouples, connectors, adaptors, and the reference junction box located inside containment form part of a core exit temper-ature. monitoring system.to be. qualified for use during-and after 'a design basis LOCA, MSLB or. seismic event.
In addition to the accident environment to which components inside containment might be subjected, the thermocouple ~ junctions in the reactor vessel are to be qualified for -
operation in the event that a LOCA might lead to inadequate core cooling (ICC). The DBE conditions to which the components are to be qualified, therefore, include a 384.90F-peak-temperature MSLB simulation (the-Westinghouse generic profile up to 4200F provides adequate margin for SNUPPS ' applications) with caustic spray and,- for the thermccouple measuring' junctions, a 22000F peak temperature inadequately cooled
. core simulation (which provides adequate margin over the SNUPPS required peak clad temperature).
The' WRD qualification program is presently incomplete. Test sequence steps of accelerated thermal aging, normal radiation and seismic simula-tion have been completed on the connectors and adaptors but a retest is currently scheduled. The reference junction box bas been aged, irradiat-ed, and seismically tested as discussed.below. The thermocouple test sequence has been completed. The status of completed testing and the justification for interim operation of the system are provided below.
Thermocouples
~
The thermocouples, including the measuring junctions and portions of
. stainless steel sheathed cable located inside the. vessel, have been subjected to seismic and LOCA conditions and demonstrated successful performance during and after the dynamic simulations. Accelerated
. thermal aging was not required because there are no organic materials in
-the thermocouple-and effects of high (normal) irradiation on the mechani -
! cal properties were evaluated and determined to not affect satisfactory performance of the sheath.
~
~ The seismic simulation test was conducted by shaker table using controll-ed multi-frequency test inputs. The thermocouples were subjected to five Operating Basis. Earthquakes (0BE) and four Safe Shutdyn Zarthquakes (SSE).
1
WESTINGHOUSE CLASS 3 The LOCA vibration simulation test was conducted by shaker table using random multi-frequency test inputs. The thermocouples were subjected to five seconds of random inputs at levels described by the power spectral density (PSD) plot.
Examples of the test response spectra (TRS) shown in Figures 1, 2, and 3 demonstrate adequate envelopment of the appropriate RRS for the-0BE, SSE, and PSD test levels, respectively. The OBE RRS is two-thirds of the SSE RRS.
Throughout the test sequence no structural damage was observed and the thermocouples functioned properly.
The thermocouples have also been subjected to a 22000F peak tempera-ture inadequately cooled core simulation and demonstrated successful performance both during and after the tests.
Connectors The thermocouple connector assemblies have been subjected to accelerated thermal aging and irradiation (gamma and beta) and seismic simulation.
The. test program is being repeated because the radiation test dose was not adequate to simulate the required Westinghouse generic post accident dose.
Actual test dose applied was 60 mega rads of Gamma and 890 mega rads of Beta.
Since SNUPPS requirements are 22.7 mega rads of Gamma and 152 mega rads of Beta the test dose applied did envelope SNUPPS require-ments.
The connector components are made of Ryton R-4, designed to tolerate high radiation exposure. Additionally, the metal outer sheath provides some shielding against exposure. Based on these facts, the additional radiation exposure is not anticipated to cause any changes in the previous successful test results.
The seismic simulation test was conducted by shaker table using con-trolled multi-frequency test inputs. The connectors were subjected to five Operating Basis Earthquakes (0BE) and four Safe Shutdown Earthquakes (SSE).
2
WESTINGHOUSE CLASS 3 The LOCA vibration simulation test was conducted by shaker table using random multi-frequency test inputs. The connectors were subjected to five seconds.of random inputs at levels described by the PSD plot.
Examples of the test response sepctra (TRS) shown in Figures 4, 5, and 6 demonstrate adquate envelopment of the appropriate RRS for the OBE, SSE, and PSD test. levels, respectively. The OBE RRS is two-thirds of the SSE RRS.
Throughout the ' test sequence no structural damage was observed and the connectors functioned properly.
A confidence test of the effects of a LOCA environment on a new LEM0 connector has shown no effect on the accuracy of the thermocouple reading. The confidence test consisted of two separate tests.
In the first test two LEM0 connectors were connected to two thermocouples at room temperature with a recorder attached to monitor results. One connector was dipped in a solution of 2750 ppm boron adjusted to a pH of 10.7 at 250C with sodium hydroxide. The other connector was left exposed to a normal atmosphere.
During the 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> exposure period both channels of output maintained an accurate output. The second test was set up on the same manner except that the thermocouples were placed in a 4000F oven and the connectors were both placed in a dry test vessel.
One connector was fitted with Raychem splice material to provide a
. watertight seal. A 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> steam test on the connectors was performed (this would be the same test conditions used for all HELB testing as discussed in. Westinghouse WCAP 8587 Methodology for Qualifying Westing-house WRD-Supplied NSSS Safety Related Electrical Equipment).
During this 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> test, again both channels of output maintained an accurate output. These results are considered relevant to the question of l
performance of aged qualification units because the '.endency for moisture to enter the-unprotected connectors is the same for both new and aged samples.
No evidence exists to suggest that the connectors will be more sensitive to LOCA effects. Pending completion of the entire sequence of connector tests, the results of the LOCA test of new connectors lend confidence of successful performance of the installed connectors. This LEM0 connector is the same as those installed at the SNUPPS plants.
Refer to SLNRC 84-0034 of February 23, 1984 for additional information.
3 1
r WESTINGH0USE CLASS 3 Thermoelectric Connectors At Callaway Plant, the interf ace with SNUPPS supplied organic thermo-couple extension cable consists of Thermoelectric connectors reinforced with Raychem heat shrink tubing to prevent separation.
The connectors
- have been subjected to the same accelerated thermal aging, irradiation and seismic simulation as the LEM0 connectors with successful results.
Since the design basis accident sequence has not been performed, a 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> confidence test was run on unaged Thermoelectric connectors with heat shrink tubing attached. Two Thermoelectric connectors were connected to thermocouples placed in a 4000F oven. A 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> steam test (utilizing the same HELB test conditions as discussed in-WCAP 8587) was performed on the connectors.
Both channels maintained an accurate output throughout the test except for two periods where the outputs exhibited fluctuations. These fluctuations coincided with oscillations in the chamber pressure due to a malfunctioning control valve. Post-test evaluation indicated that-one of the connectors was in poor condi-tion and -it is postulated that the pressure oscillations may have caused a differential pressure on the Raychem tubing which expanded it and allowed movement between the connector contacts. Since these rapid pressure oscillations are not typical plant environmental conditions, it is concluded that the tested connectors would have performed through a 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> period post accident. The tested Thermoelectric connector is the same as those installed at Callaway Plant.
Splices and Adaptors
.The splices which are used with the new-style Reference Junction Box are' qualified as-part of the ESE-43 program. The discussion of the Reference Junction Box below notes that the qualification program required a design change to improve the environmental sealing of the box. The installation of the improved new-style box requires a splice between the mineral insulated. cable (which is part of the box) and the organic thermocouple extension cable which is used in the circuits for thermocouples'and Reference Junction Box resistance temperature detectors (RTDs) in the SNUPPS design. The splice consists of an Amp connector bonding the two wire ends (four wire ends for RTD circuits),
covered by Raychem heat shrink tubing. The entire splice area is 4
Rev. 5/85
WESTINGH0USE CLASS 3 surrounded by Dow Corning 738 sealant which is enclosed in a metal outer sheath. The potting adaptors are developed by brazing a 0.25 inch diameter by 1.5 inch long cylinder onto a short piece of mineral insulated (MI) cable.
The cylinders are of stainless steel for the thermocouple adaptors and of brass for the RTD adaptors. After brazing the extension wires inside the cylinder, it is filled with a potting material which insulates the brazed joint and seals the MI cable.
The RTD adaptors wnich were installed with the new-style RJB at Wolf Creek do not contain the specified brass cylinders; however, the brass cylinders will be installed at Wolf 1
Creek prior _ to exceeding 5% of rated thermal power.
The above components were thermally aged to a simulated qualified life of one year then subjected to 80 Mrads of gamma radiation. This was followed by a LOCA/HELB simulation of steam and chemical spray enveloping a 400*F peak temperature with spray content as described in WCAP-8587. The post accident simulation enveloped SNUPPS requirements of six months at 120*F.
Due to the nature of the splice and potting adaptors and the method of installation, the splice and potting adaptors would not be subjected to any stresses which would cause concern during a seismic event.
However, seismic testing of aged samples has been completed to Westinghouse generic envelopes.
LOCA/HELB test results are as follows:
the splice and hardline adaptors, both stainless steel thermocouple and brass RTD, maintained the signal throughout the test period.
Signal deviations of a maximum magnitude of 20*F were noted at various times during the LOCA/HELB simulation.
Reference Junction Box (Old-Style)
The Reference Junction Box (RJB) has been aged, irradiated and seismi-cally tested successfully. The seismic simulation test was conducted on a shaker table using multi-frequency test inputs. The equipment was subject-ed to five (5).0perating Basis Earthquake (0BE) and four (4) Safe Shutdown-Earthquake (SSE) events.
The required SSE level is shown in Figure 8, and the required OBE-level is 2/3 SSE. The T/C RJB was mounted to a rigid test fixture utilizing procedures provided in the Technical Manual for the Model (WX-34072 T/C Reference Junction Box). The mounting hardware (mounting blocks and spacers, bolts, nuts, and washers) used for mounting the T/C RJB was supplied with the T/C RJB.
5 Rev. 5/85
WESTINGHOUSE CLASS 3 Examples of test response spectra (TRS) shown in Figures 7 and 8 demon-strate adequate envelopment of the appropriate RRS for the OBE and SSE test levels, respectively. Throughout the entire test sequence no structural damage was observed and the RJB functioned properly.
However, a problem discovered prior to the LOCA test has altered the test program. During an external pressurization test it was discovered that the NEMA enclosure was not leak tight and would allow steam to enter the box during the-LOCA test.
Previous tests had revelaed that RTD lead wires exposed to a steam environment would result in a substan-tial drop in the insulation resistance thus affecting the accuracy of the RTD. An-attempt was made to seal the entire box with a silicone potting compound and perform a confidence test.
If the potting method proved to be successful during the LOCA test, a new box was to be modified with the potting and the test program repeated.
During the confidence test of the potted box the measured insulation resistance dropped substantially on all three RTD's indicating the potting had not sealed the box and that the RTD lead wires were being exposed to steam and caustic spray. However, a review of the data revelaed little effect on the accuracy of the system (approximately 1%).
WRD will continue the investigation o<
he p ant independence of
'. insulation resistance and RTD perfort ;e.
Presev. eas of investiga-tion include the significance of data acquisition ci :uit variations and pos",1ble electro-chemical effects resulting from te;', measurement voltages in the presence of an' electrolyte, such as the H 80 /Na0H 3 3 caustic spray. Similar results are described by N. J. Selley in an
" Experimental Approach to Electrochemistry".
In conjunction with the investigation, the validity of existing IR measurement techniques used in establishing performance is being evaluated.
6
WESTINGHOUSE CLASS 3-The confidence' test performed on the potted box demonstrated that the probability of obtaining a true environmental seal on the box by this method was low and was notLrequired fo--successful performance. After removal of the potting material from the qualification test unit, the LOCA test was repeated and followed by. a post-accident simulation. This post-accident simulation was performed for 168 hours0.00194 days <br />0.0467 hours <br />2.777778e-4 weeks <br />6.3924e-5 months <br /> at 2300F.
p Upon completion of the test program-it was realized that because of the inadequate seal it would not be possible to take credit for Beta-shieldi.,g. lhis' lack of shielding increased the required TID for the post-accident simulation to meet Westinghouse generic requirements. The testidose' administered was adequate to' simulate-the 40 year normal
- operating dose prior.to a seismic event.
Because of the inadequate seal, a concern h'as been raised over long term corrosion' effects and potential hydrogen buildup to volatile levels due to containment spray reacting with the internal aluminum structure.
-However, confidence and LOCA testing with steam and chemical spray have not shown evidence of chemical residue in the box which is believed to be due to-the rapid equalization of pressure in the. box. Therefore, this is a postulated concern not demonstrated to occur during previous
-qualification testing.
'In the interim, the results of testing to date demonstrate acceptable seismic qualification and short term post-accident environmental opera-tion of the' existing box design for SNUPPS application.
Reference Junction Box (New-Style)
' Attachment 1 is a draft Equipment Qualification Data Package (EQDP) which addresses environmental and seismic qualification of the new-style RJB. The EQDP is considered to be a JIO in accordance with subparagraph
.(i) (2) of 10.CFR Part 50.49.
7 i
l
WESTINGHOUSE CLASS 3
~
Summary of Results for New-Style RJB Components The testing of the components of the core exit temperature monitoring system located inside containment demonstrated that the signal was main-tained although errors were experienced at various times during the test.
For example, as noted above, the splices and adaptors experienced a signal deviation of 20*F during HELB/LOCA simulation. Westinghouse performed an evaluation of the errors experienced during qualification testing.
Simply summing the maximum errors measured during the component test programs yields a total error somewhat less than 75'F.
An error of this magnitude is suf-ficient to provide an acceptable indication of Inadequate Core Cooling which only demands accuracies within approximately 200*F. However, information for other potential applications of the thermocouple system, such as subcooling calculations, should be derived from the more accurate wide range reactor coolant system hot leg temperature measurement which uses RTDs qualified under Westinghouse program ESE-6.
8 Rev. 5/85
-. -. -. - -.. -