ML17193B483

Containment Leakage Rate Testing,Dresden Units 1 & 2, Technical Evaluation Rept

ML17193B483
Person / Time
Site:	Dresden
Issue date:	06/11/1981
From:	Delgaizo T, Kaucher J Franklin Research Ctr, Franklin Institute
To:	Huang Y Office of Nuclear Reactor Regulation
Shared Package
ML17193B484	List: ML17193B483 ML20004F271
References
CON-NRC-03-79-118, TAC 08668, TAC 08669 TER-C5257-015, TER-C5257-015-16, NUDOCS 8106170161
Download: ML17193B483 (24)

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TECHNICAL EVALUATION REPORT CONTAINMENT LEAKAGE RATE TESTING COMMONWEALTH EDISON COMPANY DRESDEN STATIONJ UNITS 2 AND 3 NRC DOCKET NO. 50-237 / 50-249 NRC TAC NO. 08668/08669

. NRC CONTRACT NO. NRC-03-79-118 Prepared by Franklin Research Center The Parkway at Twentieth Street Philadelphia, PA 19103 Prepared for Nuclear Regulatory Commission Washington, D.C. 20555 FRC PROJECT C5257 FRCTASKS 15, 16 Author: J. E. Kaucher FRC Group Leader: T. J. DelGaizo Lead NRC Engineer:

Y. s. Huang June 11, 1981 This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States.

Government nor any agency thereof, or any of their employees, makes any warranty, expressed or implied, or assumes any legal liability or responsibility for any third party's use, or the results of such use, of any information, apparatus, product or process disclosed in this report, or represents that its use by such third party would not infringe privately owned rights.

8 I o 6 1 ? o I lo t~....

~nklin Research Center A Division of The Franklin Institute The Benjamin Franklin Parkway. Phi la.. Pa. 19103 (215) 448-1000 Doc~et # 50 - tS'1 REGULA TO.RY DOCKET f ILE CUPY Contrtl # Bl Obi '7 0 l 5 8 Date 6 B I ~ n.neument:

REGULAT(}RY ooc:~ET f'llE

TECHNICAL EVALUATION REPORT CONTAINMENT LEAKAGE RATE TESTING COMMONWEALTH EDISON COMPANY DRESDEN STATION~ UNITS 2 AND 3 NRC DOCKET NO. 50-237 / 50-249 NRC TAC NO. 08668/08669 FRC PROJECT C5257

. NRC CONTRACT NO. NRC-03-79-118 FRCTASKS 15, 1.6 Prepared by Franklin Research Center Author: J. E. K8ucher The Parkway at Twentieth Street Philadelphia, PA 19103 FRC Group Leader: T. J. DelGaizo Prepared for Nuclear Regulatory Commission Washington, D.C. 20555 Lead NRC Engineer:

Y. s. Huang June 11, 1981 This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, or any of their employees, makes any warranty, exp*ressed or implied, or assumes any legal liability or responsibility for any third party's use, or the re~ults of such use, of any information, apparatus, product or process disclosed in this report, or represents that its use by such third party would not Infringe privately owned rights.

--~-*

. ~nklin Research Center A Division of The Franklin Institute REGULA TO.RY DOCKET f ILE COPY The Benjamin Franklin Parkway. Phila.. Pa. 19103 (215) 448-1000

TER-C5257-15/16 CONTENTS Section Title 1

2 3

BACKGROUND EVALUATION CRITERIA TECHNICAL EVALUATION 3.1 Requests for Exemption from the Requirements of Appendix J

• 3.1.l Exemption from the Required Sequence of Conducting Type A and Type C Tests

• 3.1.2 Exemption from Type C Testing Requirements for Instrument Line Isolation Valves 3.1.3 Airlock Testing.

3.1.3.1 Exemption from the Required Frequency of Testing Containment Airlocks 3.1.3.2 Exemption from the Required Pressure for Testing Containment Airlocks 3.1.4 Exemption from Type C Testing Requirements for Main Steam Isolation Valves 3.1.5 Exemption from Type C Testing Requirements for Traversing Incore Probe System Valves.

3.1.6 Local Leak Rate Test Methods for the Feedwater Check.Valves.

3.1. 7 Exemption from the Type C Testing Requirements of Appendix J.

3.1.7.1 Modit°ication of Containment Air Sample Valves *

• ~nklin Research Center A Division of The Franklin Institute iii 1

2 3

3 3

6 7

7 9

12 12 13 14 14

TER-C5257-15/16 CONTENTS Section Title 4

5 3.1.7.2 Modification of Isolation Condenser Vent Valves 3.1.7.3 Modification of High Pressure Coolant 14 Injection (HPCI) System Suction Valves.

14 3.1.7.4 Exemption of Low Pressure Coolant Injection (LPCI) System Suction Valves.

15 3.1.7.5 Exemption of Core Spray System Suction Valve.

15 3.1.7.6 Exemption of Reactor Building Closed Cooling Water (RBCCW) System Supply and Return Valves

• 16 CONCLUSIONS.

17 REFERENCES

-e.nklin Research Center A Division of The F ranklln Institute 19 iv

TER-C5257-15/16

1.

BACKGROUND On August 5, 1975 [l], the NRC requested Commonwealth Edison Company (CWE) to review the containment leakage testing program for Dresden Station Units 2 and 3 (Dresden 2 and 3) and to provide a plan for achieving full compliance with 10CFR50, Appendix J~ including appr9priate design modifica-tion, changes to technical specification, or requests for exemption from the requirements pursuant to 10CFR50.12, where necessary.

CWE responded to the NRC's request in a letter dated September 26, 1975

[2], in whicfi five requests for exemption from the requirements of Appendix J were listed for Dresden 2 and 3.

On September 9, 1976 [3], CWE submitted several additional requests for exemption.

The NRC responded in a letter dated February 2, 1977 [4], providing CWE with several questions regarding these submittals.

On April 5, 1977 [5], CWE replied to the NRC's questions.

In this letter, CWE provided additional information relative to the requests for exemption from the requirements of Appendix J for Dresden 2 and 3 and also

.requested one additional exemption for Dresden. 2 and 3 regarding a proposed feedwater check valve testing procedure.

Subsequently, on April 28, 1978 [6],

CWE submitted a proposed techn.ical specification change related to reducing the minimum time requirement for conducting the integrated primary containment leak rate tests.

The purpose of this report is to provide technical evaluations of the outstanding submittals regarding the implementation of the requirements of 10CFR50, Appendix J at Dresden 2 and 3.

Consequently, technical evaluations of 'the exemption requests submitted.in References 2, 3, and 5 are included.

The issue of conducting Type A tests in less than a minimum 24-hour period is being reviewed by the NRC staff on a generic basis.

Consequently, CWE's proposal of Reference 6 is not evaluated as part of this report.

• ~nklin Research Center A OiYision of The Franklin Institute "1\\,,."

TER-C5257-15/16 2 *. EVALUATION CRITERIA Code of Federal Regulations, Title 10, Part 50 (10CFR50), Appendix J, Containment Leakage Testing, was specified by the NRC as the basis of the evaluation.

Where applied to the evaluations in this report, the criteria are either referenced or are briefly stated where necessary in support of the conclusions.

Furthermore, in recognition of the plant-specific conditions which could lead to requests for exemption not explicitly covered by the regulations, the NRC directed that the technical review constantly emphasize the basic intent of lOCRFSO, Appendix J, that potential containment atmospheric leakage paths be identified, monitored, and maintained below established limits.

~nklin Research Center A OMsion of The Franklin lnslitute TER-C5257-15/16

3.

TECHNICAL EVALUATION 3.1 REQUESTS FOR EXEMPTION FROM THE REQUIREMENTS OF APPENDIX J In Reference 2, CWE reques.ted approval of. 'the following exemptions:

Exemption from the required sequence of conducting Type A and C tests.

Exemption from Type C testing requirements for instrument line isolation valves.

Exemption from the required frequency of testing containment airlocks.

Exemption from the required pressure for testing containment airlocks.

Exemption from Type C testing requirements for main steam isolation valves.

In Reference 3, CWE requested an additional exemption from Type C testing requirements for the trave.rsing incore probe system valves.

In Reference 5,

• CWE requested an exemption from Type C testing requirements for the feedwater check valves and.other miscellaneous isolation valves.

A technical evaluation of each of these requests for exemption is included in the following sections.

3.1.1 Exemption from the Required Seguence of Conducting Type A and

• TyPe C TestsSection III.A.1.(a) of Appendix J requires that the Type A test be performed as close as practical to the "as is" condition.

When excessive leakage paths are identified during the Type A test, the test is to be terminated and leakage through such paths is to be measured by local leakage rate procedures.

After repairs or adjustments are made, a subsequent Type A test is performed.

The subsequently determined overall integrated containment leakage rate, as well as the leakage rates from the local leakage rate tests, are reported to the Commission.

~nklin Research Center A Division of The Franklin Institute...,.;:,.,..

• TER-C5257-15/16 In Reference 2, CWE stated its view concerning this requirement as follows:

"Our plan has been to conduct local leak rate tests during the first pa.rt' of an outage..

We then conduct an integrated leak rate test close to the end of the outage.

The results of the integrated leak rate test are then cor-rected back to determine the conditions that existed at the beginning of the outage using local leak rate test results."

In Reference 4, the NRC indicated to CWE that this procedure would be acceptable provided that in.correcting back to determine the results of the integrated test, a conservative assumption is applied that all measured local leakage rate is in a direction out of the containment.

In Reference 5, however, CWE asserted that the assumption that the total measured leakage of

• the local leakage rate test was in a direction out of the containment is not

• representative of the actual containment outleakage when the combined leakage of two isolation valves is measured in a single test by pressurizing between the valves.

In this case, CWE maintained that a conservative assumption would be that one half of the total measured local leakage from these valves was outleakage.

CWE s'tated:

"In those cases where the combined leakage of two isolation valves is measured i.n a single test by pres-surizing. between the valves, the above assumption can-not apply since under accident conditions, the leakage out of the containment via such a penetration would have to pass through the smaller leak rate of the two valves since it effectively throttles the flow through the penetration.

In these cases, we intend to make the most conservative assumption possible--the valves leak equally."

CWE further stated that a multiple single failure criteria imposed upon all valves measured by local leakage rate procedures was unnecessarily conservative and that their proposed procedure provided results of the integrated leakage rate test which were more nearly "as is" while the NRC's conservative assumption represented a "worst possible case."

Evaluation.

When conducting a local leakage rate test of an isolation valve located inside the containment in the direction in which it performs its safety function, sever_~J. potential leakage paths may be available which do not

~nklin Research Center A Division of The F ranklln Institute TER-C5257-15/16 result in containment outleakage (packing leaks, body-to-bonnet leaks, gasket seal leaks, etc.). Since these potential leakage paths cannot be easily separated from valve seat leakage which does result in outleakage, the NRC conservative assumption that all measured leakage is outleakage must be applied.

However, when conducting a normal Type A test, where test pressure is applied through two shut isolation val.ves in series, the actual leakage to the outside atmosphere will be no greater than the smaller of the leakage rates of the two valves taken individually. Therefore, when testing by pressurizing between the isolation valves during a local leakage rate test (assuming. that the reverse direction testing of the inboard valve is a least equivalent to or more conservative than testing in the direction of accident pressur.e), the assumption that the two valves leak equally is a conservative assumption for the purpose of back-correcting the results of the Type A test.

In fact, where one of the two valves is leaktight while the other has significant leakage, the effect of back-correcting with the assumption that both valves leak equally will add a conservatively large value to the r.esults of the Type A.test since normal Type A testing would have yielded in zero leakage through the penetration *.

The Type A testing procedures of Appendix J accounts for the possibility of active failures in determining the "'as is" c:ondition of the containment by requiring that the. isolation valves be shut by normal means without any adjustments, exercising, or other special precautions.

Consequently, if both valves shut by normal means prior to the Type A test, the test pressure is applied to the penetration with isolation provided by two shut valves in series. If one valve fails to shut, the "as is" test is performed with the single valve isolation.

Since CWE proposes to adhere to the requirements of Appendix Jin shutting the valves prior to conducting the local leakage*rate test, r.equiring that the total leakage resulting from the pressurizing between the valves be considered outleakage imposes an unreasonable conservatism in back-correcting to determine the "as is" condition.

However, should one valve fail to shut pr.ior to the local leakage rate test, after the other valve has been repaired and shut, the total measured local leakage rate (pressurizing between the valves) mu~_~_th~~-be attributed to the single shut valve and

• ~nklin Research Center

.A Division of The Franklin Institute ';:i.,

TER-C5257-15/16 therefore the assumption that the total measured leakage rate is in the direction out of the containment must be applied for this penetration.

In this way, the condition that would have existed if the Type A test were perfo~med prior to the local leakage rate test will be achieved.

Therefore, CWE's proposal to conduct local leakage rate tests prior to the integrated primary containment leakage rate test is considered to be acceptable.

When performing local leak rate tests by pressurizing between isolation valves, the assumption that the valves leak equally is acceptable when back-correcting the results of the integrated containment leakage rate test (Type A test), provided that the closure of the valves has been accomplished by normal operation* and wi:thout any preliminary exercising or adjustments in accordance with Section III.A. l. (b) of Appendix J.

3.1. 2 Exemption From Type C Testing Requirements for Instr.ument Line Isolation Valves In Reference 2, CWE requested an exemption from the requirements of paragraph II.H.l of Appendix J as relating to the Type C testing.of instrument line manual isolation valves.

The. Licensee's view *as stated as follows:

"Paragraph II.H. l specif:ies the leakage tests be conducted on isolation valves of instrument lines pene-trating the primary containment.

These manually operated valves have not been routinely tested in the past because they are not normally closed in the event of a primary con-tainment isolation, nor should they be.

These lines provide channels for the transfe.r of information about conditions inside. the.containment.

They are equipped with check valves which automatically limit excess flow thro~gh the line, should high flow conditions.develop.

These check valves are routinely tested. Since these instr.ument line manual isolation valves are not relied upon to limit the consequences of an accident, there is no basis for them to be tested periodically."

In Reference 5, CWE provided an additional technical discussion supporting the.request for exemption from Type C testing requirements for some 96 (per unit) instrument lines penetrating the drywell.

In addition to a discussion of the evaluation of the radiological consequences of the failure of one of these lines, CWE indicated that the instrument lines of both units were in accordance with.the provisions of Regulatory Guide 1.11 (Instrument Lines Penetrating Primary Reactor Containment) and its supplements.

~nklin Rese~rch Center A Oivtsion of The Frenklln Institute TER-C5257;-15/l6 Evaluation.

Section II.H.l of Appendix J requires Type C testing of containment isolation valves which provide a direct connection between inside and outside atmospheres of the primary reactor.containment under normal operat~on, such as purge and ventilation, vacuum relief, and instrument valves.

The instrument valves for which CWE has requested exemption are not those instrument valves which provide a direct connection between the inside and outside atmospheres of the containment under normal operation since these valves are open under both normal operation and post-accident conditions.

These particular valves, in fact, pr'ovide a path for leakage of primary containment atmosphere only upon a rupture or other failure of the associated instrument line.

The regulatory guidance provided to prevent unacceptable releases of radioactivity in case. of a failure or rupture of instrument lines is Regulatory Guide 1.11.

Consequently, since Type C testing of these valves is not required by Section II.H.l of Appendix J and also since the penetrations conform to the requirements of Regulatory Guide 1..11, there is no need to perform Type C testing of these valves and* no ex~mption is required.

3.1.3 Airlock Testing In Reference 2, CWE requested exemption from the Type B testing requirements for containment airlocks regarding both the frequency of testing the airlock and the pressure of the test.

Each of these requests is evaluated separately.

3.1.3.l Exemption from the Required Frequency of Testing Containment Airlocks CWE requested an exemption from the Type B testing* requirements for containment airlocks to permit testing of airlocks during each refueling outage.

CWE stated that experience indicated that testing at each refueling outage would satisfactorily ensure that the integrity of the locks would be maintained.

The NRC replied to this request in Reference 4 stating that more.

frequent testing was required because airlocks represent a potentially large

~nklin Research Center A DMsion of The Franklin Institute J

TER-C5257-15/16 leakage path that is more subject to human error than other isolation barriers.

The NRC provided CWE with additional guidance to assist the Licensee in the preparation of an acceptable program for the testing of airlocks.

In response to Reference 4, CWE submitted additional information in Reference 5 support~ng* the contention that airlocks should be tested during each refueling outage.

CWE stated,that the electrical and mechanical penetrations of the airlocks, including airlock cylinders, hinge assemblies, welded connections, and other leakage paths formed parts of rigid boundaries which are not subjected to mechanical cycling, or to the mating of seating surfaces, or to human er.ror and therefore should be tested at the same once-per-cycle interval as* other containment penetrations.

CWE further proposed to conduct a detailed visual examination of the door seals following each series of entries to ensure timely identification of developing problems.

Evaluation.

Appendix J.., Section IlI.D.2 requires that airlocks be tested at 6-month intervals and that airlocks which are opened during the 6-month

intervals be tested after each use.

Airlocks represent a poten~ially large

.leakage path that is more subject to human error than other isolation*

barriers; therefore, they are tested.more often than other isolation barriers.

In addition, toensure that the sealing mechanisms were not damaged during an airlock entry and to ensur.e tha.t these large potential leakage paths were correctly secured after use, the requirement to test after each use was added.

For certain types of reactors, airlocks have been used frequently.

Testing of airlocks after each opening, therefore, may create a situation which results in more rapid degradation of the critical isolation barriers being tested.

Moreover, experience obtained since 1969 from the testing of airlocks indicates that.only a very few ~irlock'tests have resulted in greater than allowable leakage rates.

This infrequent failure of airlock test plus

. the possibility that excessive testing could lead to a loss of reliability due to equipment degradation leads to the conclusion that testing after each opening may be undesirable.

As a compromise between the various interests, the requirement to test after each opening has been defined as within 3 days

• ~nklin Research Center

• A Division of The Franklin lnstttute TER-C5257-15/16 of each opening or every 3 days during periods of frequent openings.

By this definition, the intent of Appendix J that airlock integrity be verified within a reasonable period of time after use is achieved without the excessive testing that would otherwise be required when a series of entries (every few hours) occu'rs within a short period of time.

CWE proposes to test airlocks once-per-cycle with a detailed visual examination of the door seals following a serie~ of entries.

This testing program is not acceptable.

CWE's proposal does not make adequate allowances to detect potential deterioration of airlocks through normal use, to detect potential damage to the airlocks through moving equipment in and out of containment, and to detect possible fouling of the door seals during closure.

The detailed visual inspection following each series of openings. might reveal some of these potential problems but cannot be considered an adequate substitute for an actual airlock test.

In view of the potential consequences of failure to detect these deficiencies, use of a visual inspection in lieu of an actual test cannot be. accepted.

Consequently, the minimum acceptable air.lock testing program which complies with the requirements of Appendix J requires that the entire airlock be tested at 6-month intervals and that intermediate tests be performed within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> of each opening (or every 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> dur.ing periods of frequent opening) during the interim between 6-month tests.

CWE's request for exemption from*the requirements of Section III.D.2 is not acceptable.

3 *. 1. 3. 2 Exemption From the Required Pressure for Testing Containment Airlocks CWE has requested an exemption from the Type B testing requirements to permit airlock testing at 2 psig in lieu of peak calculated accident pressure (Pa) of 62 p~ig. As a basis for this request, CWE stated:.

"The airlock is 'designed to seal the door against a pressure of 2 psig and against 62 psig pressure of the containment vessel existing in the vessel or vessel and lock.'

Were the airlock to be tested at Pa, the inner door and door mechanism would be subjected to a force of approximately 172,000 lbs. in excess of design.

~nklln Research Center A Otvtslon of The FrankJJn Institute TER-C5257-15/16 Even with the normal mechanism augmented by the use of strongbacks, such a test is inconsistent with good engineering practice and presents an unacceptable safe.ty hazard.

In addition, the use of special restraint is contrary to the premise that meaningful data requires containment boundaries be set without employing extraordinary means.n In addition, CWE objected to performing the intermediate tests at a reduced pressure saying that even at 1 psig, the nearly 2 tons of force exerted against the inner door would cause serious threat of equipment damage, that there is no practical means of having personnel enter the drywell to inspect the inner door, and that the test would not necessa_rily be a**

meaningful representation of its ability to perform its safety function.

CWE concluded that, in view of the fact that there had been no airlock door seal failure at Dresden or at Quad Cities, a proposed.detailed visual examination

.following each series of entries in place of the reduced pressure test would provide comparable reliability and timely identification of developing problems.

Evaluation.

Appendix J,Section III.B.2 requires that airlocks be tested at*a pressure of not less than Pa.

For plants designed prior to the issuance 0f Appendix J with airlocks not designed to withstand this pressure in the reverse direction against the inner door, this criteria requires the installation of strongbacks or other holding devices to.support the normal door operating mechanism in order to per.form the test.

Due to the necessity to prove the inte.grity of this potentially large leakage source at 6-month intervals, as discussed in Section 3.1. 2.*. 1, actions necessary to support this test must be undertaken at l~ast every 6 months.

Since 1969, there have been approximately 70 instances where ai~lock leak

.tests have resulted in greater than allowable leakage rates.

However, 75% of these failures we*re caused by improper seating of door seals. Testing these seals at a reduced pressure will suffice for the purpose of verification of seal integrity following an entry, particularly in view of the fact that a full pressure containment airlock test is performed every 6 months.

Consequently, for the purpose of verification of airlock door seals following airlock openings between the 6-month tests, a reduced pressure test may be

~nklin Research Center A Division of The Franklin Institute TER-C5257-15/16 used which does not require the use of strongbacks or other holding devices provided that the results of the reduced pressure tests can be adequately extrapolated to the test results from a full pressure test.

FRC does not concur with CWE's contention that testing of airlocks at Pa is inconsistent with good engineering practice and an unacceptable safety hazard.

The door is designed to withstand the force r.esulting from peak calculated accident pressure when the pressure is on the containment side of the door.

The typical problem with pressurizing an airlock ~rom the inside is that the reverse direction pressure causes the inner door to unseat and leak to. where the test results become invalid.

The application of the strongbacks maintains the seat of the inner door seal so that a valid test can be performed.

In fact, since the 172,000 lbs of force in an actual accident condition would tend to seat the inner door, testing the airlock from within, even with strongbacks in place, provides a conservative estimate of the capability of the airlocks to seal against atmospheric leakage.

FRC also does not concur with CWE's contention that reduced pressure testing is not a meaningful repr.esentation of the abil.ity of* the airlock to perform its safety function.

Since the test is a pre.ssure drop test, the test may be conducted without inspecting the inner door..

The purpose of these intermediate tests is to ensure that the airlock has not been damaged or has not significantly deteriorated since the.last 6-month test*. Satisfactory

. performance of a pressure drop test,. with the results conservatively extrapolated to the r.esults of the Pa test, is a satisfactory indication that such degradation has not occurred.

Consequently, CWE's proposal to test airlocks at 2 psig is unacceptable.

The airlock test conducted every 6 months must be at a pressure of Pa.

• The intermediate tests performed in complicance with the "after each use" requirement of Appendix J may be performed at a reduced pressure not requiring the application of strongbacks~. provided that the test results are conservatively extrapolated to be within the acceptable criteria of the Pa test results.

These requirements conform to the recent revision to Section III.D.2, effective October 1980.

The Licensee should ensure that all requirements of the re:vised regulation are met.

~nklin Research Center A OMsion of The Frankiln Institute

.. TER-C5257-15/16 3.1.4 Exemption from Type C Testing Requirements for Main Steam Isolation Valves In Reference 2, CWE requested an exemption from the Type C testing requirements for the main steam isolation valves (MSIVs) to permit testing at 25 psig rathe.r than peak calculated accident pressure (Pa), 62 psig.

CWE's basis for this request is that the design of these valves require that_ the valves be tested by pressuriz:ing between two valves but that using a pressure of Pa will cause the inboard valve to lift off its seat (this valve is being tested in the reverse direction) and therefore erroneously high leakage rates result.

Evaluation.

The main steam system design in most operating BWR plants necess:itates leak testing of the MSIVs by pressurizing between the valves~

• The MSIVs are angled in the main steam lines to afford better sealing in the direction of accident leakage.

A test pressure of Pa acting under the inboard disc lifts the disc off its seat, resulting in excessive leakage into the r.eactor vessel.

Conside.raHon was given to this feature. when the original test pre.ssure of 25 psig. was established for. the. MSIVs at the design stage of

.the BWR plants.*

Testing of the MSIV:s at reduced pr~ssure results in a conservative determination of the leakage rate through the valves, and therefore the proposed exemption is acceptable.

3.1.5 Exemption fr.om Type C Tes.ting Requirements for Traversing Incore Probe System Valves In Reference 3, CWE requested an exemption from the Type C testing requirements of Appendix J for the traversing incore pr.obe (TIP) system valves saying that the valves were untestable.

In Reference 5, however, TIP system and purge line valves were reported to. have been successfully tested by disconnecting. the TIP tubes at fittings just inside the drywell.

By this technique, CWE was capable of testing the TIP system valves without performing any piping modifications.

CWE stated*that testing of the TIP system valves would be performed by this method in the future.

e.nklin Research Center l\\ Division of The Franklin Institute

(-..,

TER-C5257-15/16 Evaluation.

Since these valves will be tested as required by Appendix J, no exemption is necessary.

3.1. 6 Local Leak Rate Test Methods for the Feedwater Check Valves In Reference 6, CWE submitted a request for exemption concerning a modified local leak rate testing method for the feedwater check valves.

This method would use a hydraulic differential pressure across the check valves to shut the valves, then would drain the lines of fluid and conduct a local leak rate test in accordance with normal Type C testing procedures.

Thi1:1 procedure was developed because CWE discoyered tha.t without initially seating the valves using a fluid medium, the va*lves were not adequately seated and provided

• unsatisfactory test results, but* if hydraulically seated, th~ valves would perform satisfactorily.

CWE's basis for this procedure is that the revised test method simulates, as closely as possible, the normal closing operation of these valves during* accident conditions.

Since there would still be water on the valves at the time of closing due to their position in the low point of the line, the valves will initially shut by a diffe*rential pressure acting on a *column of water..

Af:te.r: the wate~ has leaked out or flashed to steam, the valves will be required to seal against potential leakage of containment atmosphere.

CWE maintains that this procedure test approximates the requirements of Section III.C.l of Appendix J with regard to the requirement to close the valves to be tested by normal oper.ation without preliminary exercising or adjustment.

Evaluation.

Section _III.C.* l of Appendix J requires that the testing of valves be performed after closing by normal operation without preliminary

-exercising or adjustments.

The method proposed by CWE approximates as closely as possible the actual conditions which will shut these valves in an accident situation.

Since the procedure is in compliance with the requirements of Section III.C.l with regard to closing the valves by normal operation, this method is acceptable.

No exemption from t-he requirements of Appendix J is necessary.

• ~nklin Research Center A Division o( The Franklin Institute -;

TER-C5257-15/16 3.1.7 Exemptions from the Type C Testing Requirements of Appendix J In Reference 3,'CWE requested several exemptions from Type C testing requirements of Appendix J.

Each of these requests is evaluated separately below.

3.1.7.1 Modification of Containment Air Sample Valves In Reference 3, CWE requested exemption from Type C testing for the drywell air l!iample valves, stating that these valves were not testable.

However, in Reference 5, CWE stated that a method would*be developed, simil~r to that used on.the TIP system, to allow testing of these valves.

Evaluation.

Since these valves w-ill be tested in accordance with Appendix J, no exemption is necessary.

3.1.7.2 Modifica~*ion of Isolation Condenser Vent Valves In Reference 3, CWE requested* an exemption from Type C tes.ting for the isolation condenser vent valves, stating that these valves were not.testable.

In Reference 5, however, CWE modified the, request to a* temporary exemption until a program could be completed to modify the valves to allow testing.

Evaluation.

Upc::>n completion of the system modifications, the valves will be tested in accordance with the Appendix. J.

No exemption is necessary.

3.1. 7. 3 Modification of HPCI Suction Valves In Reference 3,.CWE requested an exempt.ion from-Type C*testing for the HPCI suction valves, stating that these valves were not testable.

In Reference 5, however, CWE* modified the request to a temporary exemption until a program could be completed to modify the valves to allow testing.

Evaluation.

Upon completion of the system modification, the valves will

• be tested in accordance with. Appendix J *.

No exemption is necessary.

• ~nklin Research Center A Division of The F renklln Institute

. *~

TER-~5257-15/16 3.1.7.4 Exemption of LPCI Suction Valves In both References 3 and 5, CWE has requested exemption from Type C testing for LPCI. suction valves, stating that these valves have no control function, do not operate intermittently, do not respond to any isolation signal, and do not act as post-accident isolation valves.

Further, these valves are locked open to assure a suc.tion path from the torus.

Evaluation.

Section III.A.l(d) of Appendix J requires Type C testing of containment isolation valves in systems that are normally filled with water and operating after an accident. Section.II.a, however, defines containment isolation valves as. those. valves relied upon to perform a containment

• isol~tion function.. The LPCI. suction valves are locked.... open manual valves

.which are water-covered by the water inventory of the suppression pool throughout the post-accident period and* therefore are not relied upon to perform a containment isolation function.. Consequently, Appendix J does not require that these valves be* tested and. no exemption from Type Ctesting requirements. is necessa*i:y *.

.3 *. 1. 7. 5 Exemption of Core Spr.ay Suction Valves In both Refer.ences 3 and 5*,.. CWE has requested exemption from Type C testing for core suction val;ves, stating: that these valves have no control.

. function, do not' oper.ate intermittently,. do not respond to any isolation signal, and do not act as post~accident isolation valves.

Further, these valves are locked open.to assure a'suction pat,h from the torus.

Evaluation.

Section III.A.l(d) of Appendix J requires Type C testing of containment isolation valves in systems tha*t are normally filled with water arid operating after. an accident.* Section ll.B, however, defines containment isolation as those valves relied upon to: perform a containment isolation function.

The core spray suction valves are locked-open manual valves which are water-cover.ed by the water inventory of the suppression pool throughout the post-accident period and ther.efore ar.e not relied upon to perfo*rm a containment isolation function.

Consequently, Appendix J does not require that these valves be tested and no exemption from Type C testing, requirements is necessary *.

• ~nklin Research Center*

A Division of The Franldln Institute. *).*. '

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TER-C5257-15/16 3.1. 7. 6 Exemption of RBCCW Suppl.y and Return Valves In Reference 3~ CWE requested exemption from Type c testing for the RBCCW system isolation valves.

CWE states that the RBCCW system inside containment is neither part of the reactor coolant pressure boundary nor connected directly to the containment atmosphere.

In Reference 5, CWE stated.:

Our request for an exemption for these valves is based on the following:

a.

The special "closed loop inside th,e drywe.11/closed loop outside the drywell" construction of this system insures its integrity even with a single failure.

The wor.st case accident, a catastrophic pipe failure on the return line just inside the contained area, would eventually allow the. containment atmosphere to enter the RBCCW system.

(after the header had drained back to the drywell), but it would still be contained within the closed loop outside the drywell.

b.

The Tecl:iniCal Specifications do not list these valv~s as "primary containment isolation valves."

c.

The FSAR states that isolation valves in lines whiCh form a closed.

loop, either within the. containment-or outside the containment; will

• not be separately leak tested.

d.

Extensive system m0difica.tions including major valves in the supply and return lines. as we.11.as test connections would be required. to..

make this system testable. *These modifications would neither improve system sa.fety nor affect. containment integrity *.

Evaluation.

In addition to the justification provided by CWE, FRC notes that the make-up water supply to the-cooling water sy.stem expansion tank is

.. automatically provided. from. a 500,000-gallon demineralized.. water s!-orage tank.,,

using redundant make-up pumps.

Consequently, in the unlikely event that the

• • • closed loop piping inside conta*inment were to rupture,: there is sufficient

• • . water inventory to maintain a water* seal.in the closed loop outside containment by continuous system operation throughout the post-accident period.

Taking all the design aspects of the_ system together, it is concluded.

that the drywell isolation valves of this system are not relied upon to

~nklin Research Center A Division of The Franklin Institute TER-<5257-15/16 prevent the escape of containment air to atmosphere throughout the

• post-accident period.

There.fore, these valves are not containment isolation valves as defined by Section ILB of Appendix J and consequently Type.c testing is not required.

No exemption from Appendix J is required *

~nklin Research Center A Division of The Frankiln lnsUtute

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TER-C5257-15/16

4.

CONCLUSIONS This report contains technical evaluations of requests for exemption from the requirements of 10CFRSO, Appendix J, related to the containment leakage testing program at Dresden Station Units 2 and 3.

of the conclusions of. these evaluations:.

The following is a summary o

CWE!s request* for exemption to perform local valve leakage rate tests (Type C ~ests') pr.ior to the integrated primary containment leakage rate test (Type A test) and to back-correct the results of the Type A test with the r.esults of the Type c test is acceptable provided that:

0 When performing Type C testing, the conservative assumption that all measured leakage is. in a direction out of the. containment is applied unless the test is.performed by.pressurizing between the isolation valves.

When performing Type C testing by pressurizing between the isolation*

valves, the conservative assumption that the two valves leak equalli*

is applied (and therefore one.half of the measure leakage is in a direction out.* of the containment).. is. applied where the isolation valves are shut by normal oper.ation without preliminary exercising or ad.justment

• CWE' s request. for exemption* from* Type c testing for* instrument*. line*

manual isolation valves which meet the. requir.einents of Regulatory Guide 1.11~. Ins.tr.ument Lines Penetrating Primary Reactor Containment.,

is acceptable and no exemption from*Appendix. J. is r.equired.

o CWE' s proposal to test containment air*locks at 2 psig in lieu of 62 psig and to test once per cycle instead of every 6 months and a-fte.r each opening 'in the* interim is unacceptable.

The minimum acceptable program should. r.equire testing of airlocks at 62 psig once each 6 months and a reduced pressure.within 72. hours of each opening* or e.very 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> dur.ing periods of frequent openings during the* inter.im,."in accordance with the October*l980 revision to.Section III D.2 of Appendix J.

o CWE's proposal to test main steam isolation valves (at 25 psig) by pressur.izing between. the valves is an acceptable exemption to the requirements of Appendix J due to the uniqµe design of these valves.

o CWE' s pr.oposal to perform Type C testing of the traversing incore probe system valves by disconnecting the tubes at fittings just inside the drywell is acceptable.

No exemption from. the requirements of Appendix J is requir.ed.

• Y

-.~nklin Research Center A Division of The Franklin Institute*

TER-C5257-15/16 o

CWE's proposal to shut feedwater check valves using a hydraulic differential pressure of 50 psig prior to draining the lines for Type c testing is acceptable and does not require an exemption from the requirements of Appendix J.

o CWE's proposal to exclude the LPCI suction valves, core spray suction valves, and RBCCW supply and retur_n valves from Type C testing requirements is acceptable.

No exemption from the requirements of Appendix J ts necessary because Appendix J does r:iot require that these valves be-tested *

• ~nklin Research Center A Division ol The* Franklin Institute

5.

REFERENCES

1.

K. R. Goller (NRC)

Generic Letter to CWE on Containment Leakage Testing August 5, 1975

2.

G. J. Pliml (CWE)

Letter to K. R. Goller (NRC)

September 20, 1975

3.

G. L. Pliml.(CWE)

Letter to K. R. Goller (NRC.)

September 9, 1976

4.

o. L. Fiemann (NRC)

Letter to R. L. Bolger (CWE)

February 2., 1977

.5.

M. s. T.urbak (CWE)

6.

Letter to o. L. Fiemann (NRC)

April 5, 1977 C. Reed (CWE)

Letter: to E. G.* Case (NRC.)

March 21, 191.8

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• A Division of The Franklin Institute TER-C5257'-15/16.

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