ML13330A387
| ML13330A387 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 08/19/1981 |
| From: | Ray H SOUTHERN CALIFORNIA EDISON CO. |
| To: | Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8108260142 | |
| Download: ML13330A387 (5) | |
Text
Southern California Edison Company SAN ONOFRE NUCLEAR GENERATING STATION P.O. BOX 128 SAN CLEMENTE, CALIFORNIA 92672 August 19, 1981 Director of Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission Washington, D.C. 20555
-01 Hu DOCKET No. 50-206 SAN ONOFRE -
UNIT 1 REACTOR CONTAINMENT BUILDING INTEGRATED LEAK RATE TEST
Dear Sir:
An integrated leak rate'test was performed at San Onofre Unit 1 during May, 1981.
The test was performed in accordance with the requirements of the Technical Specifications. Both the measured leak rate and supplemental verification test met the acceptance criteria set forth in the Technical Specifications.
Attached is a summary technical report prepared in accordance with the reporting requirements of 10 CFR 50, Appendix J.
Sincerely, Stati Manager cc:
R. H. Engelken, Director U. S. Nuclear Regulatory Commission, Region V SS:dh:92U 4O 8108260142 8108j9 PDR ADOCK 05000206 P
PDR'
SAN ONOFRE NUCLEAR GENERATING STATION UNIT 1 REACTOR CONTAINMENT BUILDING INTEGRATED LEAK RATE TEST - MAY 15-18, 1981 INTRODUCTION A type 'A' reactor containment building integrated leak rate test (ILRT) was performed at San Onofre Unit 1 in May, 1981 during the Cycle VII-VIII refueling outage. The test was performed pursuant to the applicable requirements of San Onofre Unit 1 Technical Specification 4.3. The previous such test was completed in September, 1978 in accordance with the test frequency specified in paragraph 4.3.I.C.1(A). The results of that test were reported to the NRC by letter dated January 15, 1979.
The May, 1981 ILRT was not completed within the time interval specified in the Technical Specifications due to an extended outage involving steam generator repairs. As a result the test was conducted two months later than the required test completion date of March, 1981.
Containment integrity was not required during the two month extension.
The NRC Region V was informed of the test delay by letter dated January 29, 1981, J.G. Haynes (SCE) to R. H.
Engelken (NRC).
In accordance with the reporting requirements of 10 CFR 50 Appendix J, paragraph V.B.3, this report presents the following information:
Results of the May, 1981 ILRT test and an analysis and interpretation of these results; Results and analyses of the supplemental verification test employed to demonstrate the validity of the May, 1981 ILRT test measurements; and Results of periodic type B and C penetration tests conducted since the previous ILRT in September, 1978.
TYPE A TEST RESULTS AND ANALYSIS The containment integrated leak rate test was conducted during the period of May 15-18, 1981. The 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> test was completed at a pressure in excess of the calculated peak containment pressure, Pa, of 49.4 psig.
Data for the absolute method of leak rate calculations was taken by an Autodata-9 microcomputer at 10 minute intervals. The data was then analyzed by the formula of ANSI N45.4-1972 and Bechtel Topical Report BN-TOP-1, "Testing Criteria for Integratd Leakage Rate Testing of Primary Containment Structures of Nuclear Power Plants," November 1, 1972. In accordance with ANSI N45.4-1972, a statistical analysis and linear least squares fit was performed on the raw data.
The leak rate results are summarized below for both the total time and mass plot methods. In each case, the calculated leak rate is less than 0.090 wt%/24 hours as required by paragraph 4.3..B of the Technical Specifications.
Integrated Leak Rate Test Page # 2 ILRT RESULTS Measured Leak Rate 95% Upper (Least Squares Fit)
Confidence Level Total Time (Absolute Method) 0.038 0.049 wt%/24 hours Mass Plot (Absolute Method) 0.036 0.038 wt%/24 hours The test results for both the total time and mass plot calculations agree within instrument tolerances. The documented integrated leak rate was
.038 wt%/24 hours using a least squares fit of the total time calculation for the absolute method referenced in ANSI N45.4-1972.
During the integrated leak rate test a diurnal variation of the measured leak rate was observed over the 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> test period. This variation is expected due to the influence of atmospheric temperature changes on the uninsulated steel sphere and contained air mass. An analysis of this effect was previously provided in the March, 1977, Reactor Containment Building Integrated Leak Rate Test report.
During type C penetration testing conducted prior to the ILRT, it was discovered that the pressurizer relief tank gas space sample line, which includes containment penetration isolation valves CV-948 and CV-949, could not maintain the required test pressure. Investigation revealed that portions of the line between the isolation valves were leaking.
The damage appeared to be a result of nearby construction activities conducted during the refueling outage. The line was subsequently capped and the ILRT performed.
After completion of the ILRT it was determined that repairs would involve replacement of major portions of the line and could not be completed prior to reactor startup. As a result the line was removed from service and capped at the containment penetration. The cap was leak tested and verified to have zero leakage., Therefore no corrections to the reported type A test results will be necessary. When repairs are complete any measured penetration leakage will be added to the Type A test results and a revised report submitted.
SUPPLEMENTAL VERIFICATION TEST RESULTS AND ANALYSIS Immediately following the type 'A' test, a supplemental test was conducted in accordance with Technical Specification 4.3.I.B to demonstrate the validity of the leakage rate test measurements. A known quantity of air, measure through an orifice, was pumped back into the containment sphere. The quantity added, 380 lbm, was greater than the minimum of 354 1bm required to be added by the Technical Specifications as computed below:
Minimum amount of added air (1bm)
=
75% x total leakage allowed for 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />
.75 x.0012 x 393576 1bm (initial containment mass)
=
354 lbm
Integrated Leak Rate Test Page # 3 Comparing the quantity of air added, 380 ibm, with the change in containment air mass as measured by the leak rate instrumentation, 379 ibm, results in a difference of 1 ibm. This difference is within that allowed by the Technical Specifications as computed below:
Max allowable difference (lbm) =
25% x total leakage allowed in 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />
=
.25 x.0012 x 393576 ibm
=
118 lbm Therefore, based on review of the above results, the supplemental test verified the accuracy of the ILRT measurements.
PENETRATION TESTING Penetration (Type B and C) testing was accomplished in accordance with the requirements of Technical Specification 4.3.1.1.
The penetrations were tested by the pressure decay method using local panels and a total leakage was then determined.
The allowable leakage for all penetrations is 0.072%/24 hours of the mass of air in the containment at 49.4 psig. A summary of the results of all penetration testing accomplished between September, 1978 and May, 1981 is provided below.
These results, expressed as a percentage of the maximum allowable leakage, met the acceptance criteria of the Technical Specifications.
TEST DATE LEAKAGE (% OF ALLOWABLE) 10-28-78 35.81 10-31-78 36.60 03-23-79 59.10 03-26-79 33.17 06-18-79 31.75 09-20-79 37.91 09-26-79 38.60 02-06-80 51.75 02-08-80 51.73 03-17-80 75.24 05-12-80 65.70 05-15-81 56.10
Integrated.Leak Rate Test Page # 5
SUMMARY
AND CONCLUSIONS
- 1.
The containment integrated leak rate test accomplished during May 15-18, 1981, was completed at a pressure in excess of the calculated peak containment pressure, Pa, of 49.4 psig.
- 2.
The integrated leak rate was found to be.038%/24 hours.
This meets the Technical Specification acceptance criteria of 0.090%/24 hours.
- 3.
The pump back test performed at the conclusion of the integrated leak rate test verified the accuracy of the absolute method system within the Technical Specification acceptance criteria of 25% of.12 wt%/24 hours.
- 4.
Penetration tests performed between September, 1978 and May, 1981 met the Technical Specification acceptance criteria of.072%/24 hours.
- 5.
The next integrated leak rate test will be conducted within the 39 month (+4, -8) limit of Section 4.3.I.C.1(C) of the Technical Specifications (i.e., between December, 1983 and December, 1984).
SS:dh:92U