IR 05000237/1985015
| ML17195A771 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 04/26/1985 |
| From: | Guldemond W, Hare S NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | |
| Shared Package | |
| ML17195A769 | List: |
| References | |
| 50-237-85-15, 50-249-85-14, NUDOCS 8505030507 | |
| Download: ML17195A771 (11) | |
Text
U.S. NUCLEAR REGULATORY COMMISSION
REGION III
Report Nos. 50-237/85015(DRS); 50-249/85014(DRS)
Docket Nos. 50-237; 50-249 Licensee:
Commonwealth Edison Company P. 0. Box 767 Chicago, IL 60690 License No DPR-19; DPR-25 Facility Name:
Dresden Nuclear Power Station, Units 2 & 3 Inspection At:
Morris, IL Inspection Conducted:
March 27 through April 17, 1985
~c~~'"'---
rnspector:
S. M. Hare Approved By:
Inspection Summary Ins ection on March 27 throu h A ril 17, 1985 (Re arts No. 50-237/85015(DRS 50-249/85014 DRS )
Areas Inspected:
Routine, announced inspection by a region based inspector of licensee event reports; containment integrated leak rate test (CILRT);
Technical Specifications; local leak rate test procedure; and as found CILRT result The inspection involved 58 inspector-hours onsite by one NRC inspector including 34 inspector-hours onsite during off-shifts. Fifteen inspector-hours were expended in the Region III Offic Results:
No items of noncompliance or deviations were identified *
~gRsoaoso7 aso426 G
ADOCK 05000237 PDR
- Persons Contacted Commonwealth Edison Company
+D. Scott, Station Manager DETAILS
- +J. Wujciga, Production Superintendent
+John Achterberg, Technical Staff Superintendent
+Mary Luoma, QA Supervisor
+Bob Coen, Technical Staff Group Leader
+John 01Neill, Technical Staff, Integrated Leak Rate Test (ILRT)
Test Director Mark Leahy, Technical Staff, ILRT Test Director
+Richard Blauw, Technical Staff Larry Coyle, Technical Staff, Local Leak Rate Test (LLRT) Test Director Brian McCabe, Technical Staff, LLRT Test Engineer NRC
+T. Tongue, Senior Resident Inspector C. Anderson, Resident Inspector
+W. Guldemond, Chief, Operational Programs Section The inspector also contacted and interviewed other licensee personnel during this report perio *
+Denotes personnel present at the exit interview on April 3, 198 *Denotes personnel present at the exit teleconferance on April 17, 198.
Licensee Event Report Followup (Open) Licensee Event Report 84-23-0 Item (237/84023-LL):
Failure of as found primary containment Type B and C leak testing. A supplement must be submitted to reflect completion of testing and inspector concerns discussed in Paragraph 6 of this repor (Open) Licensee Event Report 84-019-0 Item (249/84019-LL):
Failure of as found containment Type B and C leak testing due to incorrectly calibrated leak rate test equipmen A supplement must be submitted to reflect inspector concerns discussed in Paragraph 6 of this repor.
Containment Integrated Leak Rate Test (CILRT) Procedure Review The inspector reviewed Revision 7 of procedure DTS 1600-7 entitled 11Unit 2/3 Integrated Primary Containment Leak Rate Test 11 relative to the requirements of 10 CFR Part 50, Appendix J and ANSI N45.4-197 *
The inspector's comments were discussed with the licensee prior to the performance of the CILRT and, where applicable, were incorporated into the procedure prior to the performance of the CILR Summary of Appendix J Requirements To ensure the licensee's understanding of Appendix J requirements the inspector had numerous discussions with licensee personnel during the course of the inspectio The following is a summary of the requirements discussed with the license (1) Whenever penetration configurations during a CILRT deviate from the ideal, the results of LLRTs for such penetrations must be added as a penalty to the CILRT results at the 95%
confidence leve This penetration leakage penalty is determined using the "minimum pathway leakage" methodolog This methodology is defined as the minimum leakage value that can be quantified through a penetration leakage path (e.g.,
the smallest leakage of two valves in series). This assumes no single active failure of redundant leakage barrier Additionally, any increase in containment sump, reactor water, or suppression pool (torus) level during the course of the CILRT must be taken as a penalty to the.CILRT result If penalties exist, they must be added (subtraction is never permitted) to the upper confidence level of the CILRT result (2)
The Type A test length must be 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> or longer to use the mass point method of data reductio If tests of less than 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> are planned, the Bechtel Topical Report BN-TOP-1 must be followed in its entirety except for any Section which conflicts with Appendix J requirement For either methodology, the acceptance criterion is that the measured leakage at the 95%
upper confidence limit must be less than 75% of the maximum allowable leak rate for the pressure at which the test was performe (3)
For the supplemental test, the size of the superimposed leak rate must be between 0. 75 and 1.25 times the maximum allowable leak rate L The higher the value the bette The supplemental test must be of sufficient duration to demonstrate the accuracy of the tes The NRC looks for the results stabilizing within the acceptance criteria, not just being within the acceptance criteria. Whenever the BN-TOP-1 methodology is being used, the length of the supplemental test cannot be less than approximately one half the length of the CILR (4)
An acceptable method for determining if the sum of Type B and C tests exceeds the 0.60 La Appendix J limit is to utilize the
"maximum pathway leakage" metho This methodology is defined as the maximum leakage value that can be quantified through a penetration leakage path (e.g., the larger, not total, leakage of two valves in series). This assumes a single active failure
of the better of two leakage barriers in series when performing Type B or C test The maximum pathway methodology as it applies to the Dresden station is discussed further in Paragraph (5) Future periodic Type A, B, and C tests must include both as found and as left result In order to perform Type B and C test repairs prior to a Type A test, an exemption from Appendix J requirements should be obtained from NR The exemption should state how the licensee plans to determine the as found condition of the containment since local leak rate tests are being performed prior to the CILR An acceptable method is to commit to add any improvements in leakage rates which are the result of repairs or adjustments (RAs) using the 11minimum pathway leakage 11 methodolog The minimum pathway methodology as it applies to the Dresden station is further discussed in Paragraph Instrumentation The inspector reviewed the instrument calibration data associated with performing the CILR A multipoint calibration of all instrumentation was performe Correction values were generated based on the difference between measurements ~f resistance from an NBS verified resistance box and actual resistanc All corrections were placed as an array or equation into the CILRT compute The following instrumentation was used in the CILRT:
~
RTDs Flowmeter Pressure Gauge Dewcells Pretest Requirements Quantity
1
8 The inspector reviewed the licensee's placement of the test instrumentation and found the location and number of instruments sufficient to adequately model the containment structur The inspector also verified the validity of the pre-test stabilization period and the conformance of the test prerequisites to the requirements of 10 CFR 50, Appendix J, and ANSI N45.4-197 Valve Lineup Verification Valve lineups for the following systems were verified correct to ensure that no fluid could enter the containment atmosphere and that proper venting was provided or penalties taken:
Nitrogen Inerting and Supply Service Air Instrument Air Main Steam and Main Steam Drains High Pressure Coolant Injection HPCI/Steam Exhaust Isolation Condenser Reactor Water Cleanup Reactor Building Closed Cooling Water During the valve lineup review the inspector noted that certain penetrations associated with the HPCI system were not vented and drained in accordance with Appendix J requirement The licensee corrected the situation, processing a temporary procedure change to vent those penetrations to the Reactor Buildin Test Witnessing The licensee began pressurization of the containment on March 29, 198 At approximately 15 psig the licensee discovered that the dewcells were reading out of rang The licensee elected to depressurize the containment to determine the cause of the erroneous dewcell reading After depressurization and subsequent drywell entry, the licensee determined that the out of range dewcell readings were due to water on the dewcells 1 multiplexe The water was thought to have come from water in the drywell spray header which was forced out during containment pressurizatio To prevent possible reoccurrence the licensee constructed a plastic tent over the dewcell multiplexe After containment closure, the licensee performed a zero pressure test on March 29, 1985 to demonstrate the adequacy of the test instrumentation and to verify that the containment structure was properly modele After the completion of the zero pressure test the licensee pressurized the containment and started the stabil-ization period at 5:08 a.m. on March 30, 198 The CILRT was started at 12:08 p.m. on March 30, 198 Due to computer difficulties, the licensee extended the test duration to 27.5 hour5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> A supplemental leak of 14.05 SCFH was then induced and, after obtaining a containment air sample, the verification test was started at 7:48 p.m. on March 31, 1985. Following a successful five hour verification test the licensee depressurized the containmen *
- CILRT Data Evaluation The inspector independently monitored and evaluated leak rate data to verify* the licensee's calculation of the leak rat There was acceptable agreement between the inspector's and licensee's leak rate calculations as indicated in the following summary (units are in weight percent per day):
Measurement Licensee Inseector Leakage rate calculated 0.4156 0.4112 (Lam) during CILRT Lam at 95% confidence level 0.4189 0.4140 Lam at 95% confidence level 0.4740 0.4691 adjusted to reflect penalties (refer to Paragraph 3.i)
Appendix J Acceptance Criterion at 95% confidence level= 0.75 La=
0.75 (1.6) = As indicated above, the adjusted Lam at the 95%
confidence level was less than the Appendix J acceptance criterio Sueelemental Test Data Evaluation After the satisfactory completion of the 27.5 hour5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> test on March 31, 1985, a known leakage of 1.68 weight percent/day was induce The inspector independently monitored and evaluated leak rate data to verify the licensee's calculation of the supplemental leak rat There was acceptable agreement between the inspector's and licensee's leak rate calculations as indicated in the following summary (units are in weight percent per day):
Measurement Licensee Inseector Calculated leakage (Le) rate 2.0367 2.037 during supplemental test Le @ 95% confidence level 2.0457 2.046 Induced leakage rate (Lo) =
14.05 SCFH Appendix J Acceptance Criterion:
Lo+Lam-0.25La<Lc<Lo+Lam+0.25La
- (l.695<Lc<2.495).
As indicated above, the supplemental test results satisfied the requirements of 10 CFR Part 50, Appendix CILRT Valve Lineue Penalties Due to valve ~onfigurations which deviated from the ideal penetration valve lineup requirement for the CILRT, the following penalties must be added using the minimum pathway leakage method:
- Penetration Leakage Based on the Minimum Pathway Methodology Penetration (Units are in scf/hour)
11A11 Feedwater
118 11 Feedwater 1. 22 CRD Cooling & Return
Shutdown cooling 5.26 Standby liquid control 0.516 Cleanup 2.48 Isolation Condenser 1. 41 11A11 Core Spray Injection
118 11 Core Spray Injection 0.687 11A11 LPCI Torus Spray
11A11 LPCI Containment Spray 1. 08 11A11 LPCI Test Return
11A11 LPCI Injection 1.15 118 11 LPCI Torus Spray 0.755 11911 LPCI Containment Spray
118 11 LPCI Test Return 7.64 11911 Injection 0.576 Primary Sample 0. 371 Drywe 11 Cam a. Inlet 0.848 b. Outlet 2.58 HPCI Suction 1. 72 Total = 28.29 scf/hour =.0551 Wt%/day
- Summary During the performance of the Type A test, the staff noted evidence of thorough preplanning and conscientious execution on the part of station personne No items of noncompliance or deviations were identifie.
Review of Technical Specifications The inspector reviewed the Dresden Technical Specifications for confor-mance with 10 CFR Part 50, Appendix J requirements and NRC policy regarding Type A, B and C testing. Technical Specifications Section 4.7.A.2 Paragraph c states 11the quantity of gas injected into the containment or bled from the containment during the supplemental test to be equivalent to at least 9 SCFM.
This Technical Specification does not conform with the requirements of ANSI N45.4-1972 and is not consistent with the NRC position that the quantity of gas injected or bled from containment be between 0.75 and 1.25 La (10.3 and 17.15 SCFM).
This information will be forwarded to NRR for their review and correction of the Dresden Technical Specification No items of noncompliance or deviations were identifie.
Local Leak Rate Test Procedure and Results Review The inspector reviewed Revision 10 of DTS 1600-1 and this outage 1s local leak rate test results for conformance with Regulatory requirement The inspector, after interviewing licensee personnel, found that the licensee incorrectly summed local leak rate test results to satisfy the Technical Specification Limiting Conditions for Operation (LCO) of 0.6 L The licensee stated that they were adding local leak rate test results based on an Appendix J exception from NRR dated June 25, 198 This exception states, in pa rt, that wh.en correcting Type A test results to determine an as found containment leakage, if the local leak rate tests are performed by pressurizing between two isolation valves, each isolation valve is assumed to leak equally or 50 percent of the measured leakag This corresponds to the 11minimum pathway leakage 11 methodology which is an incorrect method to add to satisfy this LC Since the majority of the licensee 1s local leak rate tests are performed by pressurizing between two isolation valves, this method could lead to very nonconservative result *
As discussed in Paragraph 3.b.4 above, the 11maximum pathway leakage
methodology is to be used to satisfy Technical Specification limits on local leakag Applying the correct methodology to the test results obtained by pressuring between two isolation valves, the maximum pathway leakage for this penetration would simply be 100 percent of the leakage measured, not 50 percent. Because the licensee was only using 50 percent of the measured leakage, the inspector briefed the licensee on the 8 *
correct methodology for adding local leak rate tests and requested the licensee to review past and present LER submittals and submit supplemental LERs in the event the original reports were incorrec In addition to briefing the licensee on the correct methodology for adding local leak rate test results, the inspector suggested that the licensee incorporate into procedure DTS-1600-1 this methodology to ensure that the local leak rate test results will be added correctly in the futur This is considered an open item (237/85015-0l(DRS)) pending the inspector's review of any supplemental LER submittals and the revised Local Leak Rate Test procedur No items of noncompliance or deviations were identifie As Found Condition of CILRT Results The "as found" condition is the condition of the containment at the beginning of the outage prior to any repairs or adjustments (RAs) to the containment boundar CFR 50, Appendix J, Paragraph III. requires that 'During the period between the initiation of the contain-ment inspection and the performance of the Type A test, no repairs or adjustments shall be made so that the containment can be tested in as close to the "as is" condition as practical. 1 ANSI N45.4-1972, Paragraph 4.2 requires "For retesting, an initial record proof test shall be conducted at time periods and pressures established by the responsible organization, before any preparatory repairs are made.
This will disclose the normal state of repair of the containment structure and a record of the results shall be retained." The NRC' s position on the "initial record proof test 11 requirement, as contained in the June 25, 1982, Appendix J exemption, is that it may be waived, provided the Type A test results are back corrected for all RAs to the containment boundary made prior to the performance of the Type A tes If RAs are made to the containment boundary. prior to the Type A test, local leak rate tests must be performed to determine the leakage rates before and after the RA The "as found" Type A test results can then be obtained by adding the difference between the affected path leakages before and after RAs to the overall Type A test result These "as found 11 leakage rate results are required and carry the same reporting requirements as the other Type A and supplemental test result The correct methodology for back correct the Type A test results, as described in Section 3.b, Paragraph 5 of this report, is the minimum pathway leakage methodolog As discussed in Section 6 of this report, the Appendix J exemption request prescribes a method of determining individual valve leakages when test pressure is applied between two isolation valve The licensee was literally following this guidance for determining the as found condition of the containment when the inspector arrived on sit At the beginning of the inspection, the licensee stated that the as found penalty was on
the order of 500 SCFH (0.6) La and in order to pass the as found Type A test requirement, the as left Type A leakage would have to be less than 0.15 La (0.75-0.6 = 0.15).
Upon further investigation the inspector found that even when the licensee could quantify an individual valve's leakage, they would still take 50 percent of the total measured leakage and assign it to each valv While this is conservative in most cases, there are instances where this assumption is not conservativ After discovering this, the inspector independently calculated an as found leakage penalty and found that the licensee 1s calculation was five times larger than it should have bee Subsequently, the inspector noted to the licen~ee that in any situation where they can conservatively quantify an isolation valve 1s leakage (e.g., repair only one of the two isolation valves), the minimum pathway leakage methodology is to be used (e.g., the smaller of the isolation valves' leakage is the penetration through-leakage).
The inspector noted durihg the April 3, 1985 exit interview that the licensee should incorporate this methodology into the Type A test procedure to ensure uniform interpretation in the futur This is considered an open item (237/85015-02(DRS)) pending the inspector 1s review of the revised test procedur *
The inspector reviewed as found and as left local leak rate test results to determine an as found Type A test resul The following is a summary of the as found containment leakage rate (units are in weight percent/
day):
Measurement Penalties incurred due to repairs or adjustments prior to the CLIRT:
As Found Type A test results:
0.1961 0.6701 Appendix J acceptance criteria for the 11as-found 11 condition of the con-tainment= 0. 75La = 1.2 wt%/da Due to past as found test failures in 1979 and 1983 the licensee is on an accelerated Type A test schedule pursuant to the 10 CFR Part 50, Appendix J, Section III.A. Because this test is considered to have passed in the as found condition, the licensee need only pass the as found Type A test during the next refueling outage to return to the normal Type A test schedul No items of noncompliance or deviations were identifie.
Open Items Open items are matters which have been discussed with the licensee, which will be reviewed further by the inspector, and which involve some action on the part of the NRC or licensee or bot Open items disclosed during*
this inspection is discussed in Paragraphs 5 and * Exit Interview The inspector met with licensee representatives (denoted in Paragraph 1)
on April 3, 1985 and summarized the scope and findings of the inspection activit-ie The inspector noted the acceptable results of the Type A as found results and noted the good performance of the licensee 1s staff during the CILR The licensee acknowledged the inspector 1s statement Additional information concerning this inspection was discussed on April 17, 1985, during a telephone call between the inspector and Mr. Wujciga of your staff.
11