ML20087L451
| ML20087L451 | |
| Person / Time | |
|---|---|
| Site: | Catawba  |
| Issue date: | 03/16/1984 |
| From: | Tucker H DUKE POWER CO. |
| To: | Adensam E, Harold Denton Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8403270213 | |
| Download: ML20087L451 (4) | |
Text
e DUKE PowEn GOMPANY P.O. ISOX 33180 CitAM!.OTTE, N.C. 28242 HALB.TUCKEM Tet.m ens *xn we raamanes?
(704) 073-4531 March 16, 1984 Mr. Harold R. Denton, Director Office of Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission Washington, D. C. 20555 Attention:
Ms. E. G. Adensam, Chief Licenaing Branch No. 4 Re: Catawba Nuclear Station Docket Nos. 50-413 and 50-414
Dear Mr. Danton:
On February 9, 1984 representatives from Duke Power Company and the NRC staff met to discuss the environmental qualification of D. G. O' Brian electrical penetrations. Attached are responses to the follow-up questions from that meeting.
Very truly yours.
YJ.B.C<~l~ / &
Hal B. Tucker ROS/php Attachment cc:
Mr. James P. O'Reilly, Regional Administrator U. S. Nuclear Regulatory Commission Region II 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30303 NRC Resident Inspector Catawba Nuclear Station Mr. Robert Guild, Esq.
Attorney-at-Law P. O. Box 12097 Charleston, South Carolina 29205 Palmetto Alliance 2135h Devine Street
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Columbia, South Carolina 29205 Mr. Jesse L. Riley Carolina Environmental Study Group 854 Henley Place 9a" Charlotte, North Carn 14na 0403270213 840316 DR ADOCK 05 g
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.CATEWBA NUCLEAR STATION Response to NRC Request for Additional Information Concerning D.G. O'Brien Electrical Penetrations The following information is provided in response to five specific questions raised by the NRC Staff concerning the environmental qualification of D.C.
O'Brien electrical penetrations.
To' ensure proper perspective, two aspects of the :nvironmental qualification of these pe >etrations should be noted.
First, the environmental qualification program including the manufacturer's test, the Sandia tests, and the Duke tests was an evolutionary process.
Lessons were learned from each test not only in terms of equipment capability, but also in terms of good practices for conducting meaningful qualification tests.. The objective of the Duke' qualification program was to incorporate the lessons learned from previous testing into a program to establish reason-abic assurance that the penetrations / connectors are capable of performing their safety function.
Secondly, conservatisms in the qualification program must be considered when
. reviewing the results of the program. Specifically, conservatism in the Duke program exists' in-the test. profiles (which included margin), in the fact that two LOCA simulations were ren on the same penetration, and in the IR measuring
~
technique.
Question 1 Provide ' justification as to why it was not necessary to repeat the 340'F excursion in the extended LOCA test in order to determine qualification of the type K penetration.
Response
The penetration test setup inclu'ed a provision for measuring the penetration d
connector temperature during each test.
Section 7, page 44 of the first Wyle test shows the maximum temperature of the connector due to the heat transfer characteristics of the assembly to be 250*F.
Therefore, the second Wyle test was designed to~ simulate the same temperature effects at the connector as measured in.the first Wyle test without the need to repeat the initial transient excursion. - Section 3, page 31 of the second Wyle test confirms that the temperature effects at'the connector surface were as severe in the second test as in the first test.
r
. Question 2 Provide justification that the insulation resistance measurements for the type K penetration shown in the qualification test report are acceptable in regard
.to maintaining required instrument loop accuracy.
e Page 2 of 3
Response
The insulation resistance measurements taken during the Wyle tests were made in an extremely conservative manner. By measuring IR from one connector pin to all other pins in the connector which were tied together and to ground, the actual IR measurement represents many parallel paths to ground.
Based on Duke's review of the actual IR measuring setup, it was determined that the instrument used to make this measurement during the Wyle tests was not capable of reading below 500Kn resistance.
Therefore, any measurements indicating below 500KG are inconclusive.* However, a review of the original D.G. O'Brien test results showed a corellation to the Wyle test results in regard to the behavior of the type K module.
Further, the D.G. O'Brien test employed an instrument capable of measuring below 500KQ. From the D.G.
O'Brien test results, it can be confirmed that the IR did drop below 500Ka with a minimum measured resistance of 200KD.
It should also be noted that the test results demonstrate the IR dip to be a long term phenomena (48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> per the second Wyle report) which does not affect the required short term trip function accuracies.
The effect of a 200KQ insulation resistance has been analyzed for all Catawba safety circuits which must remain functional in the long term post accident utilizing a type K module. The results indicate that thc required long term circuit accuracies can be maintained at a penetration assembly insulation resistance of 200KO.
In summary, the Wyle tests alone do not provide sufficient data to address the decrease in insulation resistance below 500KO. However, there is similarity in all three tests (D.G. O'Brien Wyle Tests 1 and 2) in regard to a long term phenomena resulting in a decrease and subsequent increase of insulation resistance. Based on this similarity, the extremely conservative method of measuring the insulation resistance (i.e., the measurement represents multiple parallel paths to ground), and the Catawba circuit analyses, it is concluded that the tests verify the adequacy of the type K module for their Catawba applications.
Question 3 Address the significance of the insulation measurements of "less than 0.5 megohms" for the type K penetration at the 42 hour4.861111e-4 days <br />0.0117 hours <br />6.944444e-5 weeks <br />1.5981e-5 months <br /> point of the extended test.
(
Reference:
Table III-3.VI)
Response
This issue is addressed in the response to Question 2.
- The same instrument used in the penetration test program was demonstrated to be erratic below 500M] during a recent Duke visit to the Wyle facilities.
Therefore, all readings in the Wyle test giving a specific value less than 500KG are in error.
The test report will be cerrected to read "<500KG" for all these cases.
Page 3 of 3 Question 4 Address the leakage currents of " greater than 5000 microamps" for the high potential tests performed on the type K penetration at the 178 hour0.00206 days <br />0.0494 hours <br />2.943122e-4 weeks <br />6.7729e-5 months <br /> point of the extended test.
(
Reference:
Table III-3.VI)
Response-All leakage currents noted in the Wyle tests were taken with AC potential which is not applicable to the Catawba applications. The applicable parameter is DC insulation resistance which is addressed in the response to Question 2.
Question 5 Address the reasons for or significance of the low insulation resistance readings in the first test on the type K penetration.
Response
The primary reason for the type K module low insulation resistance readings during the first Wyle test is attributed to cable insulation breakdown.
This cable insulation breakdown was due to mishandling of the cable test specimen after thermal and radiation aging. The significance of low readings is addressed in the response to Question 2.
Add 1tional Information In addition to the review of the Type K modules noted above, one additional instrumentation module (Type H-Triax) has been identified that is intended to remain functional in the long term post accident environment.
This penetrction module serves the high range containment radiation monitor.
This instrumentation performs a monitoring fuaction only and provides no automatic protection actions.
It should be noted that the original Catawba design did not require this module to be environmentally qualified.
liowever, as a result of NRC mandated plant modifications stemming from TMI, it became necessary to employ this module in conjunction with the containment high range radiation monitor (NUREG 0737, Item II.F.1).
Based on penetration data then available, the performance of the Type H module was expected t3 be similar to the other modules. This was the basis of the initial application. Additional evaluation is ongoing to determine final acceptability and will include current leakage considerations.
This evaluation will be completed by the March 31, 1985 date of the environuental qualification rule (10CFR 50.49).
,