IR 05000327/1989010
ML20246N048 | |
Person / Time | |
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Site: | Sequoyah ![]() |
Issue date: | 05/04/1989 |
From: | Belisle G, Whitener H NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
To: | |
Shared Package | |
ML20246N033 | List: |
References | |
50-327-89-10, 50-328-89-10, NUDOCS 8905190336 | |
Download: ML20246N048 (9) | |
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UNITED STATES
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NUCLEAR REGULATORY COMMISSION
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REGION ll.
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101 MARIETTA STREET,N.W.
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ATLANTA, GEORGI A 30323
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Report Nos.:
50-327/89-10 50-328/89-10
!I Licensee:
Tennessee Valley Authority 6N38 A Lookout Place
'1101 Market Street Chattanooga, TN 37402-2801
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Docket Nos.:
50-327 and 50-328 License Nos.:
DPR-77 and DPR-79 Facility Name:
Sequoyah 1 and 2
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t Inspection Conducted: March 16,-20, 1989 Inspector:
Y,I h
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- - M - b H. L. Whiten r)
Date Signed Approved by:
6-me /
f-tT /
g. A. BelisTe, Chief Date Signed Test Programs Section e
Engineering Branch Division of Reactor Safety SUMMARY Scope:
This routine announced inspection was conducted in the areas of witnessing containment integrated leak rate testing, reviewing test procedures, and evaluating test results.
Results:
In the areas inspected, violations or deviations were not identified.
Within the scope of this inspection, the findings indicated that the licensee had developed a thorough leak rate test program.
The inspector observed that management was actively involved in the test; staffing was adequate and knowledgeable of Appendix J requirements; the test procedure was detailed and comprehensive; and, in general, the licensee's resolution of problems was conservative.
Excessive leakage through penetration X-59 caused the containment integrated leak rate test (CILRT) to exceed the leakage limit specified in 10 CFR 50, Appendix J.
Therefore, the CILRT was classified as a l
failed test.
Since this failure is the second consecutive failed test on Unit 2, the licensee must perform a CIRLT at each refueling outage until two consecutive tests are successful.
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8905190336 890504 i
PDR ADOCK 05000327 G
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' REPORT DETAILS 1.
Persons Contacted Licasee Employees
- F. Bodi.", Mechanical Engineer
- J. Casey, Mechanical Test Supervisor
- S. Childers, Operations
- K. Clark, Containment Programs Supervisor M. Cooper, Compliance Supervisor
- M. Cutlip, Test Director
- R. Fortenberry, Technical Support Superintendent
- J. LaPoint', Site Director
- S. Smith, Plant Manager Other licensee employees contacted during this inspection included engineers, operators, mechanics, and leak rate test personnel.
- Attended exit interview 2.
Containment Integrated Leak Rate Test - (70313) (Unit 2)
.The inspector reviewed and witnessed test activities to determine that the ' primary containment integrated leak rate test was performed in accordance with the requirements of Appendix J to 10 CFR 50, ANSI N45.4-1972, BN-TOP-1, Revision 1-1972, and test _ procedure SI-156, Containment Integrated Leak Rate Test.
Selected sampling of the licensee's activities which were inspected included: -_1) reviewing the test procedure to verify that it was properly (
approved and conformed with regulatory requirements; (2) observing the test performance to determine that test prerequisites were completed, special equipment was installed, instrumentation was calibrated, and appropriate data were recorded; and (3) evaluating the preliminary leak rate data to verify that leak rate limits were met.
l Pertinent aspects are discussed in the following paragraphs.
a.
General Observations The inspector witnessed and reviewed portions of the test preparation, containment pressurization, temperature stabilization,
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and data processing during the period from March 16-20, 1989, and concluded the following:
(1) The test was conducted in accordance with an approved procedure.
Procedure changes and test discrepancies were documented.
(2) Selected test prerequisites were found to be complete _ _ _
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(3) Plant systems required to maintain test control were found to be operational.
(4) Special test instrumentation was found to be installed and calibrated.
(5) Data required for performing the. containment leak rate calculations were recorded at 10-minute intervals.
(6) Problems encountered during the test were described in the test event log.
(7) Pressurized gas sources were properly isolated and vented to preclude in-leakage or interference of out-leakage through containment isolation i,alves.
(8) Selected procedure valve alignments were reviewed against system drawings to verify correct boundary alignment, and venting and draining of specific systems.
(9) Temperature, pressure, dew point, and flow data were recorded at'
10-minute intervals.
Data were assembled and retained for final evaluation and analysis by the license.
A final Integrated Leak-Rate Test (ILRT) report will be submitted to the Office of Nuclear Reactor Regulation.
b.
Test Procedure Review - Unit 1 and Unit 2 (70307),
The inspector reviewed portions of SI-156, Revision 11 to verify that adequate test controls, acceptance criteria, and valve alignments were specified.
Also, change instruction forms for four procedure changes were reviewed and discussed with test personnel..These changes reflected plant modifications, changes in calibration methods for pressurizer level input to the data collection system, changes in the method to disable the safety injection actuation signal, additions to the penetration path leakage summary, and the addition of a plan for identifying containment leakage during the test.
Procedure valve alignments for a limited selection of systems were also reviewed.
Systems reviewed were high pressure nitrogen supply to accumulators, hydrogen gas analyzer, service air, reactor coolant drain tank discharge to waste, essential raw cooling water discharge, and reactor coolant pump seal water return, c.
Test Performance - Unit 2 (1) Method i
The licensee had data analysis capability for the total time analysis in accordance with requirements of BN-TOP-1 for a short duration test and mass point-linear regression analysis in
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accordance with the recommendations of ANSI /ANS-N56 8-1981 for a 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> test.
In this test the data met the BN-TOP-1 criteria.
Consequently, a short duration test -of 10.66. hours and a verification tect of 5.33 hours3.819444e-4 days <br />0.00917 hours <br />5.456349e-5 weeks <br />1.25565e-5 months <br /> were performed using the total time analysis method stated in BN-TOP-1.
(2) Test Description Pressurization of the containment was initiated at 3:26 p.m. on March 16 and was terminated at 8:20 a.m. on March 17 at 27.23 psia.
The stabilization period was initiated at this time.
In the period from 8:30 a.m. to 2:30 p.m. on March 17, the data indicated an excessive leakage of approximately 6 wt. percent per day.
A large leak was identified through the Essential Raw Cooling Water (ERCW) discharge line, penetration X-59.
An attempt to isolate X-59 was made at 2:00 p.m. by closing valve 67-777 which vents the penetration to containment atmosphere.
Also, at about 2:30 p.m., operations closed outside isolation valve 77-10 in penetration X-46, Reactor Coolant Drain Tank (RCDT) discharge line to waste.
Valve 77-09, the inside isolation valve for penetration X-46, was blocked open for the type A test.
The combination of the two evolutions reduced leakage from 6 wt. percent per day to approximately 0.3 wt.
percent per day.
Further search by the licensee identified that penetration X-59 was still leaking.
This penetration was finally isolated at 2:00 a.m. on March 18 by closing outside vent valves 67-693A and 67-693C which allowed the discharge line to pressurize out to the ERCW discharge header block valve.
Subsequent to this isolation, preliminary indications showed a reduction in leakage rate to 0.02 vt. percent per day.
The sequence of test events are described in tne following table:
Date Time Event Description 3/16/89 1526 Started containment pressur-ization.
3/17/89 0820 Pressurization terminated at 27.23 psia. Started stabilization period.
0830 Compressors isolated and vented.
1100 Leakage survey in progress.
Containment leak rate about 6 wt. percent per day.
The leakage appeared to be through penetration X-59, ERCW discharge line.
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Date Time Event Description
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s 1400 Valve 67-777 inside contain-I ment closed to isolate
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penetration X-59.
I 1430 Valve 77-10, outside
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isolation valve for RCDT discharge, closed.
1450 Based on 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> of data, the leak rate was 0.03 wt. percent per day.
1840 Sump pumped down.
2030 Maintenance entered containment to blank off any openings in coolers on the ERCW line.
3/18/89 0118 Coolers isolated, but X-59 still leaking.
0200 Outside vent valves 67-693A and 67-693C closed.
This isolated penetration X-59 and X-63.
0815 Verified that stabilization temperature criteria were met over the previous 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />.
0841 Time Zero for start of containment ILRT.
1711 Meet BN-TOP-1 criteria.for end of test.
Continued taking data until verifi-cation flow could be setup.
2002 Verification test started.
3/19/89 0125 Verification test completed.
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(3) -Test Results - Unit 2 (a) Type A Test Technical Specification allowable' leakage (La) for Sequoyah'
Unit 2 is 0. 25 wt. percent per day.
Therefore, the integrated leak. rc.ce test leakage limit of 0.75 La as required by Appendix J is 0.1875 wt. percent per day.
In-the period following containment stabilization.the containment leakage was approximately 6 wt. percent per day which exceeded the test acceptable limit of 0.1875 wt.
percent per day.
Subsequent to closing ' the _ RCDi isolation valve penetration X-46, and the inboard vent valve penetration X-59, the leakage was reduced to about 0. 3 wt. percent per day.
Isolating penetration'X-59.by.
closing the outboard vent valve reduced the leakage. to within the allowable leakage rate.
The following are th?
results of the leak rate measurement and the leak ratt compensated for error for both the Mass Point (MP) analysis according to - ANSI /ANS 56.8 and total-time (TT) analysis according to BN-TOP-1:
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Measured Leak Rate 95% Upper Confidence Limit MP 0.028 wt. percent 0.032 wt. percent per day-per day TT. 0.011 wt. percent 0.062 wt. percent per day per day The inspector concluded that, subsequent to isolating penetrations X-46 and X-59, containment leakage was within the allowable leakage of 0.1875 wt. percent per day.
(b) Supplemental Test - Unit 2 Appendix J requires that a supplemental test be performed to verify the accuracy of the Type A test and the ability of the containment ILRT instrumentation to measure a change in leak rate.
The following is an acceptable supplemental test method as described in Appendix C of ANSI N45.4 -
1972:
A known leak rate (Lo) is imposed on the containment and the measured composite leak rate (Lc) must equal, within 10.25 La, the sum of the measured leak rate (Lam) plus the known leak rate (Lo).
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The acceptance criteria is expressed'as:
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I Lo + Lam - 0.25 La < Lc < Lo + Lam + 0.25 La A 5.3 hour3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> verification test was performed.
The following measured values were obtained (Units are in wt. percent per day):
TT MP Lam 0.0113
'0.0279 Lo 0.2658 0.2658 Lc 0.2658 0.2723
.25La 0.0625 0.0625 Substitution these values into the acceptance criteria shows that the inequality was satisfied as follows:
Mass Point *'0.2312 <0.2723 <0.3562 Total Time * 0.2146 <0.2658 <0.3396
- Units are in.wt. percent per day
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inspector concluded that the verification test The
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. containment leak rate.
d.
Type A Test Status - Unit 2 The initial containment leak rate was greater than the test acceptance limit defined as 0.75 La in 10 CFR 50, Appendix J, Paragraph III.A.5(b).
As previously discussed in paragraph c.(3)(a)
and in accordance with Appendix J.
Paragraphs III.A.1(a) and III. A.6(b), the test was identified as a failed test.
This is the second consecutive failed Type A test for Sequoyah Unit 2.
Paragraph III. A.6(b) requires that if two consecutive periodic Type A tests fail to meet the applicable acceptance criteria in III. A.5(b),
notwithstanding the periodic retest schedule of III.D, a Type A test shall be performed at each plant shutdown for refueling or approximately overy 18 months, whichever occurs first, until two consecutive Type A tests meet the acceptance criteria in III. A.5(b),
after which time the retest schedule specified in III.D may be resumed.
Although the precise figure had not been calculated, the licensee estimated that the leakage correction factor to determine the "as found" leakrate was about '17 SCFH or 0.02 wt. percent per day.
With a calculated total time leakrate of 0.062 wt. percent per day, the corrected Type A leakage would be about 0.08 wt. percent per day which is well below the 0.75 La limit of 0.1875 wt. percent per
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As a result, the licensee did not initiate the Type A test with a failed test due to repaired leakage.
However, in performing
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the Type A test,' excessive containment leakage was identified which required isolating penetrations X-46 and X-59 before the-acceptance limit of Appendix J, Paragraph III. A.5(b) could be met.-
By the requirements of Appendix J, Paragraph III. A.1(a), this is a
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failed test and the penalty of paragraph III.A.6(b) is invoked.
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At the exit interview, the inspector identified the test as performed
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as a failed integrated leak rate test in accordance with the i
requirements of Appendix J.
The inspector also acknowledged that the
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licensee has documented test results which indicated - that the
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excessive leakage through penetrations X-46 and X-59 did not exist at the time the plant was shutdown. for refueling.
The inspector indicated that the NRC would evaluate the findings of the licensee's investigation into the cause and implications of the leakages.
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Subsequent to the inspection, Region II informed licensee management l
that penetration X-46, Reactor Coolant Drain Tank discharge. to
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waste, need not be considered in ' determining the pass / fail status.of the integrated leak rate as discussed below.
Concerning the leakage through penetration X-59, the licensee has the option to request an exemption from the requirements of Appendix J, Paragraph III. A.6(b).
As a minimum this would involve identifying the root cause of the leakage and demonstrating that an alternate corrective action plan is more appropriate to the problem than an accelerated Type A test schedule.
Penetration leakage through X-46 was eliminated from consideration in evaluating the pass / fail status based on the Regions review of the cause of the leakage during the. test, and system design for normal operation and post accident conditions.
Although a weakness in the test procedure and an operator error were involved, leakage through penetration X-46 is largely attributable to the abnormal system condition for the test.
Specifically, the pump stops and an in-line level control valve (failed open during the test) isoletes the discharge line when the RCDT reaches a 20 percent level.
Also, the two automatic isolation valves in penetration X-46 receive a phase A containment isolation signal and close in the event of an accident condition.
The Region concluded that subsequent to restoration and alignment of systems for plant startup; during normal plant operations; and, in post accident conditions, there is reasonable assurance that' penetration X-46 will be isolated.
3.
Exit Interview The inspection scope and results were summarized on March 20, 1989, with those persons indicated in paragraph 1.
The inspector described the areas inspected and discussed in detail the inspection results.
Proprietary information is not contained in this report.
Dissenting comments were not received from the licensee.
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As previously discussed, licensee management was informed that.the
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L containment ILRT did not meet Appendix J requirements, and was considered l
to be a failed test as performed.
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