IR 05000010/1977025
| ML19338C996 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 09/27/1977 |
| From: | Kohler J, Little W NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | |
| Shared Package | |
| ML19338C995 | List: |
| References | |
| 50-010-77-25, 50-10-77-25, NUDOCS 8009150477 | |
| Download: ML19338C996 (6) | |
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U.S. NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT
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REGION III
Report No. 50-010/77-25 Docket No. 50-10 License No. DPR-2 Licensee:
Commonwealth Edison Compuny Post Of fice Box 767 Chicago, IL 60690 Facility Name: Dresden Nuclear Power Station, Unit 1.
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Inspection at: Dresden Site, Morris, IL Inspection coeducted: August-23-26, 1977 y& "kolibr' ~ [
f Inspector:
E.
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Approved by:
W.
S.
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Nuclear Support Section-
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Inspection Summary Inspection on Aucust 23-26, 1977 (Report No. 50-010/77-25)
Areas Inspected: Routine, announced inspection of the containment structural integrity test and integrated leak rate test.
The inspec-tion included thirty hours of onsite time by one NRC inspector.
Results:
No items of noncompliance or deviations were identified.
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DETAILS
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1.
Persons Contacted I
- B.
R. Shelton
- R. J. Yungk
- R. Kyrouac, Quality Assurance
- C.
E. Sargent. Technical Staff Supervisor
- C. Reimers, Engineer, Technical Staff
- D. Farrar, Assistant Technical Staff Supervisor
- P.
Duggan, Engineer, Technical Staff I
- N.' Scott, Operating Engineer, Unit 2
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R. Rowland,-Quality Assurance
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J. Doyle, Quality Assurance H. Davy,. Quality Assurance R.-Nimmer, Engineer Assistant, Technical Staff E. Bussean, Engineering Assistant, Technical Staff S. Harris, Engineer, Technical Staff 2.
Primary Containment Bellows Structural Integrity Test
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Following installation of ten primary containment bellows it was
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i determiaed by ONRR that a structural integrity test should be I
performed at 110% Pa (22 psig). Five attempts were made by the
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licensee between July 31, 1977 and August 31, 1977 to complete this test successfully. However, each of the first four tests were unsuccessful when pinhole leakage was discovered along both i
circumferential and longitudinal bellows welds. These pinholes
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i were repaired by wciding and retesting involving repressurizing the. containment.
i On August 31, 1977, the containment successfully passed the structural integrity test.
The acceptance criteria for the test are contained in ASME B 31-1 section 137.4.2, NE 6215.
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3.
Exemption from E10 CFR 50, Appendix J for Nontestable Bellows i
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- During review of the acceptability of the replacement primary
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containment bellows, it was determined that the nontestable bellows design, selected by the licensee as replacement articles
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_did not meet the surveillance requirements of 10 CFR 50, Appendix J.
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I The licensee applied for an exemption from the requirement
to subject these bellows to periodic localileak rate tests.
This item is under GNRR review.
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RIII Concerns on Replacement Bellcws In the five attempts to perform the structural integrity test, j
some twenty pinholes were discovered at both low (5 psig) and i
maximum pressures (22 psig).
Because of the number of pinhole indications discovered during the SIT at both low and maximum pressure, the inspector suspected that the welds might be opening due to bellows movement as the containment is pres-surized.
Present surveillance requirements contained in the
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Dresden 1 Technical Specifications and 10 CFR 50, Appendix J require testing 'these bellc>ws no sooner then the next scheduled refueling outage, approximately a twelve month period, should the
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' licensee receive an NRC extension to operate af ter December 31,.1977.
In view of the concern to maintain Dresden 1-containment leakage
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within allowable technical specification limits, the inspector l
requested ONRR to require the following additional surveillance tests during the next scheduled operating cycle:
Monitor pipe movecent. during operating cycles to determine
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whether bellows are experiencing more movement than deter-mined analytically.
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b.
Af tar six month's operation or four heatup - cooldown cycles on the bellows, whichever comes first, perform another 22 psig pneumatic test of the primary containment bellows, using a soap solution to check for leakage.
Acceptance criteria should'be no leakage.
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l The requirement for additional surveillance test is presently
under ONRR review.
5.
10 CFR 50.59 Review of Bellows During the management exit' the inspector stated that the 10 CFR f
50.59 review of the bellows was deficient:
it did not identify the field weld along the longitudinal axis of the replacement bellows as differing from the original bellows which contained no lorgitudinal field weld; it. did not analyze the flexibility of the longitudinal field weld to yield during thermal cycles.
I The insoector was concerned that the longitudinal field weld on
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the bellows was of lesser quality than the original installation and would not stand up under the expected cyclic movement of the bellows:during plant ope ra t ion.
Because of the concern the inspector stated that he was asking for additional information c
l-concerning this. item.
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1977 Dresden 1 Containcent Integrated Leak Rate Test
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During the period between August 23-25, 1977, the licensee perforned the containment integrated leak rate test.
Data was taken from the computer system every ten minutes and leak rate calculation was made using the absolute method of analyzing containment mass changes.
Although a stabilization period of four hours was observed prior to commencement of the test, the licensee had no containment temperature stabilization criteria in the procedure.
It was felt that the uninsulated Dresden 1 containment would readily reflect changes in outside tenperature and never stabilize if large tenperature differentials during night and day existed
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during testing. This proved to be the case.
The containment average temperature varied between 81 - 90 F during testing and experienced strong diurnal changes.
The variation in containment temperature caused noticeable changes in the calculated containment leak rate.
The licensee took data for 39 hours4.513889e-4 days <br />0.0108 hours <br />6.448413e-5 weeks <br />1.48395e-5 months <br />.
During this tire the calculated leakage rate varied from a low of about.25 w/o/ day to a maximum of about.45 w/o/ day coincid'ing with the hottest portion of the
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noon day.
The 11owing summaries re flect the ef fect the change in containment average temperature had on the calculated leakage rate.
These calculations were made using data and regression analysis performed by the inspector.
Time Period Leakage Rate w/o/ day 0-39 hours
.31 +.02 Maximum.45 Minimum.25 The inspector determined during data talking that there was excellent agreement between the inspectors and licensee calculation as can be seen by the following comparison.
Leak Rate w/o/ day Licensee Inspector 0-14.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />
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Calculated leak rate
.3224
.3257 Upper confidence level
.3317
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The licensee stated that for official purposes he had selected the 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> period fcr 0700 on August 24 to 0700 on August 25
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Jas ~ the of ficial 1977 Dresden 1 calculated leakage rate. Analysis of the ' data taken during this time period yielded the following
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!f 95% upper confidence level leakage rate.
Licensee Inspector-T/s Limit
.75 T/s Limit t
0700'8/24--
e 0700 8/25
.2527
.2716
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Supplement Test
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On August.25, 1977, a superimposed leak equivalent to.23 w/o/ day (11 scfm) war established and data collected every ten minutes.
The. measured leakage rate.was determined by the inspector to be
.477 w/o/ day af ter 4.33 hours3.819444e-4 days <br />0.00917 hours <br />5.456349e-5 weeks <br />1.25565e-5 months <br /> of data * collection. After sub-
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tracting the superimposed leakage rate the actual leakage rate
was.239 w/o/ day.
The results of the superimposed leak test were within the acceptance criteria specified by 10 CFR 50, Appendix J.
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TL 2refore,.the CILRT was acceptable.
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8.
Containnent Leakaee Discovered During CILRT
During the CILRT the licensee was investigating leakage from the following penetrations:
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Heating Steam Supply to Sphere
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Flow Control Valve 510 li Sphere pressurization Line l
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s The licensee ' committed to repair these penetrations _ so that the
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identified leakage would either be eliminated or reduced. The steps the licensee has taken to correct thic containment leakage
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will be requested in a response to this inspection report.
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Unresolved Items Inspection Peport 50-010/77-21 (Closed) Performance of a structural integrity test after a.
modifications to the primary system are complete.
(Para-g, graph 2)
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(Closed) Installation of testable seals on all bellows found leaking.
(Paragraph.3)
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(Closed) Installation of testable seals on all bellows that form' part of the ' primary containment.
(Paragraph 3)
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(Closed) Schedule for completion of containment modifications
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with respect to future operation of Dresden 1.
( All modifi-cations completed as of August 31, 1977.)
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Future Schedule for CILRT Attempts at demonstrating that the containment leak rate at Dresden I was within allowable Technical Specification limits failed on two consecutive occasions in 1974 and 1977. Conse-quently, according to 10 CFR 50 Appendix J,Section III A.6.b, a Type A test shall be performed at each plant shutdown for refueling or approximately every 18 months whichever occurs first until two consecutive Type A tests neet acceptance criteria.
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Service Air and Instrument Air During the test, action had to be taken by the licensee to positively isolate the service and instrument air isolation valves, contrary to 10 CFR 50 Appendix J.
The licensee will be requested to describe the steps t? ken to maintain these paths isolated during hypothetical design basis accident conditions in a response to this inspection report.
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12.
Exit Interview An exit interview was conducted at the conclusion of the inspection in which the inspector stated his conclusions regarding the 1977 Dresden 1 CILRT.
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