IR 05000456/1986023
| ML20211B137 | |
| Person / Time | |
|---|---|
| Site: | Braidwood  |
| Issue date: | 02/13/1987 |
| From: | Maura F, Mendez R, Wright G NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | |
| Shared Package | |
| ML20211B079 | List: |
| References | |
| 50-456-86-23, NUDOCS 8702190325 | |
| Download: ML20211B137 (11) | |
Text
.
.
.
.
U.S. NUCLEAR REGULATORY COMMISSION
REGION III
Report No. 50-456/86023(DRS)
Docket No. 50-456 License No. NPF-59 Licensee: Comonwealth Edison Company Post Office Box 767 Chicago, IL 60690
'
Facility Narre: Braidwood Station, Unit 1 l
Inspection At: Braidwocd Site, Braidwood, Illinois Inspection Conducted: May 25, 1986 through January 29, 1987 SY)!{nistA.
Inspectors:
F. Maura J/n/P7 Da'te '
fhfaua R.Mendez},.
a////f7
'Da t'e
.
e.
Approved By:
G. C'. Wright, Chief 41// //87 Test Programs Section Dqte
.
'
Inspection Summary Inspection on May 25, 1986 through January 29, 1987 (Report No. 50-456/86023(DRS))
_
the containment integrated leak rate test (CILRT)y Region based inspectors of Areas Inspected: Routine, anncunced inspection b procedure, witncssing the CILRT, review of CILRT results, review the local leak rate test procedure and test results, review of post CILRT work in containment, and review the CILRT results report dated August 19, 1986. This inspection was conducted per
.
Inspection Procedures No. 61720, 70307, 70313, 70323 and 90713.
Results: Of the six areas inspected, no violations or deviations were Tdentified in five of the areas. One violation was identified in the remaining area (fsilure to follow the requirements of Appendix J - Paragraph 6.a).
t a
f
.-.
- -- - -
.
..
-.
- - -. -... -. - -. -.
.-
- -.
.
.. -
,
-_
_ _ _ _
.
(
.
DETAILS 1.
Persons Contacted M. Azar, Engineer, Technical Staff xy P. Barnes, Supervisor, Regulatory Assurance x K. Buzesk, Engineer, Technical Staff D. Evan, Engineer, Technical Staff xy E. Fitzpatrick, Station Manager xy B. Peacock, Engineer, Technical Staff xy C. Schroeder, Services Superintendent xy D. Shamblin, Assistant Project Manager yDenotes persons attending the preliminary exit meeting at the conclusion of the CILRT on May 30, 1986.
xDenotes persons attending the exit meeting of January 29, 1987.
The inspectors also contacted other licensee personnel including members of the technical, operating, and regulatory assurance staff.
2.
Containment Integrated Leak Rate Preoperational Test Procedure Review (Unit 1)
a.
Procedure Review The inspector reviewed preoperational test Procedure BW PT-PC-11, Revision 1, " Integrated Lea ( Rate Test" including Test Change Requests No. 1 through 7 for conformance with 10 CFR 50, Appendix J; the FSAR; and the SER.
The inspectors' comments were discussed with the licensee by telephone on May 22, 1986.
All inspectors' comments were satisfactorily resolved.
b.
Clarification of Appendix J Requirements To ensure the licensee's understanding of Appendix J requirements, the inspector conducted numerous discussions with licensee personnel during the course of the inspection.
The following is a summary of the clarifications discussed with the licensee.
(1) The only methods of data reduction acceptable to the NRC are total time or point-to point as described in ANSI N45.4-1972 including a statistically calculated instrument error analysis.
The following options are available to the licensee:
(a) Total time (<24 hour duration test) in accordance with Bechtel Corp. Topical Report BN-TOP-1, Revision 1.
WheneverBN-TOP-1isuseditmustQefollowedinits entirety except for any section which conflicts with Appendix J requirements.
.
.
_
-
.
(b) Total time (>24 hour duration test) using single sided 95% UCL.
(c) Proposed Regulatory Guide MS 021-5, Regulatory Position No. 13.
If this method is utilized, the licensee must submit as exemption request to NRC and receive approval for its use prior to the expiration of the Type A test frequency requirements stated in the Technical Specifications.
(2) Periodic Type A, B and C tests must include as-found results aswellastheas-left.
If Type B and C tests are conducted prior to a Type A, the as-found condition of the containment must be calculated by adding any improvements in leaka whicharetheresultsofreaaltsandadjustments(R&A)gerates, to the
Type A test results using t1e " minimum pathway leakage methodology. This method requires that:
(a) In the case where individual leak rates are assigned to twovalvesinseries(bothbeforeandaftertheR&A) the penetrationthrough-leakagewouldsimplybethesmaller of the two valves leak rates.
(b)
In the case where a leak rate is obtained by pressurizing between two isolation valves and tha individual valve's leak rate is not quantified, the as-found and as-left penetration through-leakage for each valve would be 50 percent of the measured leak rate if both valves are repaired.
(c)
In the case where a leak rate is obtained by pressurizing between two isolation valves and only one valve is repaired, the as-found penetration leak rate would conservatively be the final measured leak rate, and the as-left penetration through leak rate would be zero (this assumes the repaired valve leaks zero).
(3) Penetrations which are required to be Type C tested, as described in the FSAR and SER, must be vented inside and outside the containment during the CILRT.
All vented penetrations must be drained of water inside the containment and between the penetration valves to assure exposure of the containment isolation valves to containment air test pressure.
The degree of draining of vented penetrations outside of containment is controlledbytherequirementthatthevalvesbesubjectedto the post-accident differential pressure, or proof that the system was built to stringent quality assurance standards comparable to those required for a seismic system.
(4) 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 level.
The penetration leakage penalty is determined using
F
.
.
the " minimum pathway leakage" methodology.
This methodology is defined as the minimum leakage value that can be quantified through a penetration leakage, path (e.g., the smallest le:kage of two valves in series).
This assumes no single active failure of redundant leakage barriers.
Any incresce in containment sump, fuel pool, reactor water, or suppression pool level during the course of the CILRT must also be taken as a penalty to the CILRT results.
If penalties exist, they must be added (subtraction is never permitted) to the upper confidence level of the CILRT results.
(5) The start of a CILRT must be noted in the test log at the time the licensee determines that the containment stabilization has been satisfactorily completed.
Reinitializing a test in progress must be " forward looking,"ision to restart is made.that is, the new start tim the time at which the dec This also implies that the licensee has determined that the test has failed, and has enough data to quantify the leakace rate.
Any deviation from these positions should be discussec, and documented with the NRC inspector as they occur to avoid later invalidations,
of the test results.
Examples of acceptable deviations of reinitializing the start time of the test in the past are:
time at which a leaking penetration which has an obvious effect on the test data was secured, accidental opening and later closing of a valve which has an obvious effect on the test data the time at which an airlock outer door was closed and the inner, door was open.
(6) The supplemental or verification test should start within one hour after the completion of the CILRT.
If problems are encountered in the start of the supplemental test, data recording must continue and be considered part of the CILRT until the problems are corrected and the supplemental test can begin.
(7) For the su)plemental test, the size of the superimposed leak rate must ae between 0.75 and 1.25 times the maximum allowable leak rate La.
The higher the value, the better.
The supplemental test must be of sufficient duration to demonstrate the accuracy of the test.
The NRC looks for the results to stabilize within the acceptance criteria, rather than the results 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 of the CILRT.
(8) DuringaCILRT,itmaybecomenecessarytorejectordelete specific sensors or data points due to drifting or erroneous sensors, or data outliers.
Datarejectioncriteriashouldbe developed and used so that there is a consistent, technical basisfordatarejection.
One example of an acceptable method for data outliers is described in an appendix to ANSI /ANS 56.8-1981.
__
.
Sensor data rejection criteria should be )lant specific and based upon a sensor's trend relative to t1e average scatter, slope, and/or absolute output of the sensor.
(9) The water level in the steam generators during the CILRT must be low enough to ensure it does not enter the main steam lines unless flooding of the main steam lines is called for in the loss of coolant emergency procedure.
(10) An acceptable method for determining if the sum of Type B and C test exceeds the 0.60 La Ap)endix J limit is to utilize the
" maximum pathway leakage" metlod.
This methodology is defined as the maximum leakage value that can be quantified through a penetrationleakagepath(e.g.,thelarger,nottotal, leakage oftwovalvesinseries).
This assumes a single active failure to the better of two leakage barriers in series when performing Type B or C tests.
(11) Test connections must be administratively controlled to ensure their leak tightness or be subject to Type C testing.
One way to ensure their leak tightness is to cap, with a good seal, the test connection after its use.
Proper administrative controls should ensure valve closure and cap reinstallation within the local leak rate testing procedure, and with a checklist prior to unit restart.
(12) Whenever a valve is replaced, repaired, or repacked during an outage for which Type A, B, and/or C surveillance testing was scheduled, local leak rate testing for the as-found as well as the as-left condition must be performed on that penetration.
In the case of a replaced valve, the as-found test can be waived if no other containment 1 solation valve of similar design exists at the site.
No violations or deviations were identified.
3.
Containment Integrated Leak Rate Test Witnessing (Unit 1)
a.
Instrumentation The inspector reviewed the calibration data and determined all the instruments used in the CILRT had been )roperly calibrated and that the correct weighting factors had aeen placed in the computer program as required.
The following instrumentation was used throughout the test:
_ Type Quantity y
Dewcells
Pressure Gauges
Flowmeter
4
n
.
One out of eight RTD's in Subvolume No. 3 was deleted from the data scan early during the reduced pressure test due to erratic (large stepchange) behavior.
No other sensors and no data sets were rejectedduringthetest, b.
Temperature Survey The inspector reviewed the results of the temperature surveys performed by the licensee days prior to containment pressurization.
One survey was performed with no reactor containment fan cooler fans (RCFCF) running and the second with two RCFCFs running.
The reduced pressure CILRT was performed with two RCFCFs on slow speed while the full gressure CILRT had no fans in operation.
The review of the data, especially the one with no fans running showed large temperature gradients (u No. 4 and 5)p to 13.6 F) within the lower two subvolumes (Subvolumes The inspector challenged the location and quantity of
.
RTDs in those two subvolumes based on the temperature survey data.
The licensee stattd the surveys had been performed with the airlock doors open and, therefore, were not representative of the test conditions.
It was agreed that another survey would be )erformed following'the CILRT with all containment doors closed, tie lights off, and the RCFCFs off.
On May 30, 1986, the inspector witnessed two temperature surveys of Subvolume No. 4 and 5 performed approximately one hour and five hours after containment depressurization.
The largest temperature gradient recorded was 2.6 F and the largest change recorded between the two surveys was 1.3 F, both on Subvolume No. 5.
Theaveragetem)eraturechangein each subvolume between each survey was 0.1 F.
T1e inspector has no further concerns.
c.
Witness of Test The inspector witnessed portions of the reduced pressure and full pressure CILRTs on May 25-28, 1986, and noted that test prerequisites were met and that the appropriate revision to the test procedure was followed by test personnel.
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:
!
System Penetration (s)
Chilled Water P-5 6 8 and 10 Reactor Building Drains and Vents P-lian,d$5
Service Air P-56 3" Primary Water Supply P-44 ReactorCoolant(PressurizerRelief)
P-27 Containment Purge P-94, 95, and 97
Off Gas Hydrogen Recombiners P-13, 23, and 69 Instrument Air P-39 During the start of the reduced pressure test the pert'nnel airlock inner door shaft seal leaked excessively.
The licensee closed the
!
outer door and opened the inner door for the duration of the tests.
!
i r
!
F.
.
The start time of the reduced pressure test was reinitialized to Data Set No. 49, or 30 minutes after the opening of the airlock inner door.
The inspector requested that the licensee investigate the reason for the airlocks shaft seals failure since they had recently been tested locally with satisfactory results.
After the CILRT were disassembled and cleaned; however, the licensee, the shaft seals stated that no reason for their failure during the CILRT could be found.
The seals were replaced with a new type per the vendor's (CB&I) recommendation.
The new shaft seals were tested with satisfactory results.
No violations or deviations were identified.
4.
Test Results Evaluation a.
Reduced Pressure CILRT Data Evualation Upon satisfactory completion of the required temperature stabilization period a 24-hour CILRT was performed at 38.7 psia (.65 Pa) during May 25'26,inutes.
1986, with data being collected and reduced by the licensee every 15 m The inspectors independently monitored and evaluated the leak rate data to verify the licensee's calculation of the leak rate and instrument performance.
There was excellent agreement between the inspectors' and licensee's results as indicated by the following summary (units are in weight percent per day).
Measurement Licensee Inspector Leakage rate measured duringILRT(Ltm)
0.036 0.036 Ltm at upper 95%
confidence level 0.039 0.039 A)pendix J acceptance criteria - This test in combination with tie full pressure ILRT is used to establish the maximum allowable leakage rate Lt for future reduced pressure tests at Pt = 38.7 psia, b.
Full Pressure CILRT Data Evaluation Following completion of the reduced pressure CILRT, the containment was pressurized to s60 psia and a 24-hour CILRT performed during May 26-27, 1986, following satisfactory completion of the required temperature stabilization period.
Data was collected and analyzed by the licensee every 15 minutes.
The inspectors monitored and evaluated the leak rate test data to verify the licensee's calculations of the leak rate and instrument performance.
Again there was excellent agreement between the inspectors' and licensee's results as indicated by the following sommary (units are in weight percent perday).
.
.
Measurement-Licensee Inspshtor Leakage rate measured duringILRT(Lam)
0.029 0.029 Lam at upper 95%
confidence level 0.033 0.033 Appendix J acceptance criteria 95% UCL = <0.75 La = <0.075 wt %/ day.
Appendix J acceptance criteria for future reduced pressure tests:
(1) Lt (at Pt = 24 psig) = <La VPt/Pa = <0.1 (0.735) = <0.074 wt %/ day.
(2) <0.75 Lt = <0.75 (0.074) = <0.056 wt %/ day.
c.
Supplemental Test Data Evaluation After the satisfactory completion of the full pressure 24-hour CILRT a known leakage (based on inspectors independent readings and calculations) of 7.70 scf/ min, equivalent to 0.100 weight )ercent per day was induced.
Data was collected and analyzed by tie licensee every five minutes.
The inspectors independently monitored and evaluated the leak rate data to verify the licensee's results.
After approximately six hours the supplemental test was terminated withsatisfactoryresultsasIndicatedbythefollowingsummary (unitsareinweightpercentperday).
Measurement Licensee Inspector Measured leakage rate, Lc, during supplemental test 0.111 0.111 Induced leakage rate, Lo 0.100
, 0.100 Lc - (Lo + Lam)
-0.018 '
-0.018 Appendix J acceptance criteria: - 0.025 < [Lc - (Lo + Lam)] < + 0.025 d.
Recirculation Sump Pipe Penetration Each recirculation sump penetration sleeve has a valve which vents the sleeve-to pipe cavity to the containment atmosphere.
This valve, which is normally closed, was not included in the CILRT 1rocedure.
Following the CILRT, the licensee determined that tie penetration boundary did not txperience test pressure during the CILRT.
The licensee performed local tests and the results were added as a penalty to the CILRT results at the 95% UCL.
(RefertoSection4.e penetrations P-92 and P-93.)
ThelicenseehasmodifiedthepIpingconfigurationofUnit1to make the valve more accessible.
The ins)ector reviewed Surveillance Procedure 18wSV 6.1.2.a-1, Revision 0, " Yimary Containment Type A Integrated Leakage Rate Test" and determined that Data Sheet 1.6
"SafetyInjection,"includesarequirementtohavetherecirculat. ion sum) penetrationsleeveventvalves(ISI091Aand8)openforthe CILIT.
The inspector has no further questions regarding this item.
.
_
.
.
e.
CILRT Valve Lineup Penalties Due to valve configuration which deviated from the ideal penetration valve lineup requirements for the CILRT, the results of local leak rate test for such penetrations must be added as a penalty to Lam at the 95 percent UCL. The following penalties were added using the minimum pathway-leakage method:
Local Leak Rate Test Value Based Penetration on Latest Test, (units are in sccm)
P-82 Steam Generator Blowdown 2A 716 P-83 Steam Generator Blowdown 2B
P-80 Steam Generator Blowdown 2B 400 P-81 Steam Generator Blowdown 2D
P-88 Steam Generator Blowdown 2E
P-89 Steam Generator Blowdown 2F
P-90 Steam Generator Blowdown 2G 100 P-91 Steam Generator Blowdown 2H
P-52 Process Radiation Equipment Hatch
P-4 VQ Containment Pressurnation Line
I-3 VQ Instrument Taps
P-93 Recirc Sump B Bellows 149 1574-This leakage rate is <0.001 wt %/ day which when added to the measured Lam at the 95% UCL gives a value well within the acceptance criteria of <0.075 wt %/ day.
No violations or deviations were identified.
5.
Review of Post CILRT Work in Containment The inspector discussed with the licensee the control of work activities inside containment.
The licensee indicated that construction activities inside containment would continue after the CILRT, but that the work activities would be controlled.
By letter dated May 30, 1986, the licensee informed all contractors that any) activity affecting the containment liner (welding cutting, grinding, etc.
requires the written approval of the
)
Ceco Pro ect Construction Department.
The inspector, along with licensee personne, walked down the containment liner at the 377', 401' 410' and 426' elevations on January 28, 1987.
The inspector looked for indentations, gouges and burn marks.
During the walkdown, the inspector noted one gouge at Elevation 377' with i
a surface area of about 0.15 inches 2 and approximately 1/8 inch dee;.
l The licensee removed the paint coating and it was determined that tie
gouge did not penetrate completely through the containment liner.
The l
licensee also performed calculations and determined that the integrity of the liner at accident conditions would not be impaired by the presence of the gouge; therefore, no further action would be taken.
The inspector
'
has no further concerns regarding the condition of the containment liner.
!
l l
_ _ _ _ _ _ _ _ _ _ _
_ _ _ _ _ _
_
_--_ -__________ _ ____ ______ __________ ___ _
,__.
-
.
a The Type A test was performed with the liner weld leak chase channel 1/4" plugs installed.
The licensee plans to conduct all future Type A tests
with the plugs installed.
During the preliminary exit of May 30 1986,
the licensee was informed that they must submit to NRR their justification for the performance of Type A tests with the channel plugs installed.
As of January 29, 1987, the licensee has taken no action on this item and was againremindedtoobtainNRRacceptanceoftheirplantotest(TypeA)
with thegleak chase channel plugs installed.
This is an Open Item (456/86023-01) pending licensee submittal to NRR, and NRR acceptance, of thejustificationtoconductTypeAtestswithchannelplugsinstalled.
6.
Local Leak Rate (Type B and C) Preoperational Test a.
Procedure Review The inspector reviewed preoperational test procedure Bw PT-PC-10, Revision 0, " Primary Containment B and C Local Leakage Rate Test,"
for testing method, acceptance criteria, and penetrations to be tested and determined that it met the requirements of 10 CFR 50, Appendix J, ANSI N 45.4 and the FSAR commitments with one exception.
10CFR50,dppendixJrequiresthatcontainment penetrations fitted with expansion bellows be~ Type B leakage rate tested.
A review of the containment penetrations showed that the fuel transfer tube is fitted with three expansion bellows which are part of the containment boundary.
The licensee's.preoperational test procedure Bw'PT-PC-10 Rev thefueltransfertubebellows.ision0~didnotir.cludetestingof The-licensee had not received an
'
exemption from the testing requirements of Appendix J for the fuel transfer tube bellows.
Failure to establish a preoperational testing program and develop a periodic test program which includes the fuel transfer tube bellows of Unit 1 is a violation of 10CFR50,AppendixJ(456/86023-02).
Following the identification of this violation by the inspector the licensee tested the fuel transfer tube bellows at Pa with s:tisfactory results.
During January 1987, the inspector reviewed test procedure 18w VS 6.1.2.d-1, Revision 0, " Primary Containment Type B and C Local Leakage Rate Tests," Section 5, and noted that Steps 5.11 through 5.22 cover the leakage rate testing of the fuel transfer tube sleeve bellows.
The inspector determined that the licensee took adequate corrective action with regards to this violation; therefore, no further action is required.
The inspector reviewed the following specific pe;1etration testing procedures to ensure 1 roper venting and draining"and the use of a satisfactory test metled.
No problems were identified.
(1) Stea No. 9.5 - Fuel Transfer Tube Penetration Blind Flange
<
Lea < age Rate Test (2) Step No. 9.6 - Equipment Door and Integral Personnel Lock Lea < age Rate Test
...
.
.
-.
c.
,
f (3) Step No. 9.8 - Containment Purge System (VQ) Local Leakage RateTest(coveringPenetrationsP 94, 95, 96, 97 and I-3)
(4) Step No. 9.10 - Chemical and Volume Control System (CV)
local Leakage Rate Test (covering Penetrations P-28 and 41)
(5) Step No. 9.11 - Reactor Building Drains and Vents System (RE)
local Leakage Rate Test (covering Penetrations P-11 and 65)
b.
Test Results Review The inspectors reviewed the results of all Type B and C final pre operational tests and determined that:
(1) The sum of all containment penetration boundaries and isolation valves leakage rate f. including the summation of the errors)
using the maximum pathway method was 38.07 scfh or 0.08 La, where the acceptance criteria is <0.6 La.
(2) Where specific containment boundaries had a more restrictive Technical Specification acceptance criteria (such as airlock gaskets, containment normal purge isolation valves and mini-flow purge isolation valves) the results were well within the Technical Specification limits.
(3) Whenever the initial test gave unsatisfactory results, the licensee wrote a deficiency on the specific boundary, the problem was corrected and the boundary retested.
c.
Reverse Direction Testing The insp(ectors reviewed the design of the twelve inboard isolation valves three plug valves, one globe valve and eight butterfly valves) which are tested in the reverse dir,ection.
The review showed that testing in the reverse direction gives equivalent or more conservative results than when testing in the direction of accident pressure.
7.
Review of Braidwood Unit 1 Reactor Containment Building Integrated Leakage Rate lest Report The inspector reviewed the licensee's " Reactor Containment Building Integrated Leakage Rate Test for Braidwood Unit 1" report submitted to the NRC on August 19, 1986, and determined that it accurately reports the leakage rates and events regarding the Unit 1 Type A, B, and C tests performed during the preoperational test program for the unit.
No violations or deviations were identified.
,_
.
_ _ _
_
_
_
__
_
-
-.
_
..
,
8.
Open Items Open items are matters which have been discussed with the licensee, which will be reviewed by the inspector and which involve some action on the part of the NRC or the licensee or both.
An open item disclosed during the inspection is discussed in Paragraph 5.
9.
Exit Interview The inspectors met with licensee representatives denoted in Paragraph 1 during the inspection on May 30, 1986, and at the conclusion of the inspection on January 29, 1987.
The inspectors summarized the scope and findings of the inspection. The licensee acknowledged the information and did not indicate that any of the information disclosed during the inspection could be considered proprietary in nature.
l l
l
!
l l
l l
t