ML20207H168

Forwards Request for Exemption from 10CFR50.12,App J Type C Leak Rate Testing of RHR & Upper Head Injection Sys & Pressure Relief Valves,Per Unresolved Items Noted in Insp Repts 50-327/86-20 & 50-328/86-20.Fee Paid

ML20207H168
Person / Time
Site:	Sequoyah
Issue date:	12/31/1986
From:	Domer J TENNESSEE VALLEY AUTHORITY
To:	Youngblood B Office of Nuclear Reactor Regulation
References
NUDOCS 8701070473
Download: ML20207H168 (9)

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TENNESSEE VALLEY AUTHORITY CHATTANOOGA. TENNESSEE 374o1 SN 157B Lookout Place DEC 311986 Director of Nuclear Reactor Regulation Attention: Mr. B. Youngblood, Project Director PWR Project Directorate No. 4-Division of Pressurized Water Reactors (PWR)

Licensing A U.S. Nuclear Regulatory Commission Washington, D.C. 20555

Dear Mr. Youngblood:

'In the Matter of ) Docket Nos. 50-327 Tennessee Valley Authority ) 50-328 SEQUOYAH NUCLEAR PLANT - CONTAINMENT ISOLATION SYSTEM - EXEMPTION FROM APPENDIX J LEAK TESTING - RESIDUAL HEAT REMOVAL AND UPPER HEAD INJECTION SYSTEMS AND PRESSURE RELIEF VALVES IE Inspection Report Numbers 50-327/86-20 and 50-328/86-20, transmitted from J. A. Olshinski to S. A. White by letter dated April 23, 1986, identified unresolved items 50-327/86-20-09 and 50-328/86-20-09, Containment Isolation Design Pertaining to the Chemical and Volume Control System. One of the activities undertaken by TVA to achieve closure of the preceding two unresolved items was the redesignation of remote manual valves in residual heat removal (RHR) system and upper head injection' (UNI) system lines just outside of containment as containment isolation valves. A second activity undertaken was the redesignation of-pressure relief valves on the safety injection system control volume and chemical system, and the containment

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spray system as containment isolation valves.

The redesignated remote manual valves in the RHR and UHI lines and the redesignated pressure relief valves were evaluated with respect to testing requirements for containment isolation valves in accordance with 10 CFR 50 Appendix J. As a result of the evaluation, it is our determination that a type C leak rate tost cannot be performed with either the RHR or UNI systems, nor the pressure relief valves, as they are currently configured. Also, the evaluations performed have convinced us that the design features of the two systems and the pressure relief valves provide adequate justification, as required by 10 CFR 50.12, to support a request for exemption from 10 CFR 50 Appendix J type C leak rate testing for both the RHR and the UHI systems and the pressure relief valves.

This submittal transmits a belef description of the RHR and UHI system j configurations following a postulated loss of coolant accident (LOCA), a brief j description of the pressure relief valves and piping, design features of those i h 0 L -

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-the applicable basis for requesting'an exemption from type C leak rate testing under the criteria of 10 CFR 50.12 for the two systems and the pressure relief valves. -We request that you review our request for exemption and advise us in writing of your determination.

Enclosed is a check for the $150 application fee required by 10 CFR 170.12 for the review of our request for exemption.

Please direct questions concerning this request to Timothy S. Andreychek at 615/870-7470.

Very truly yours, TENNESSEE VALLEY AUTHORITY

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J. A. Domst, Assistant Director

, Nuclear Safety and Licensing Sworntopdsubscri before me th 3/ day of b 1986 J /])

' Notary Public My Commission Expires i i Enclosure cc: See page 3

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Director of Nuclear Reactor Regulation cc (Enclosures):

U.S. Nuclear Regulatory Commission Region II Attn: Dr. J. Nelson Grace, Regional Administrator 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30323 Mr. James Taylor, Director Office of Inspection and Enforcement U.S. Nuclear Regulatory Commission Washington, D.C. 20555 Mr. Carl Stahle Sequoyah Project Manager U.S. Nuclear Regulatory Commission 7920 Norfolk Avenue Bethesda, Maryland 20814 Mr. G. G. Zech Director, TVA Projects U. S. Nuclear Regulatory Commission Region II 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30323 i

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ENCLOSURE REQUEST FOR EXEMPTION FROM APPENDIX J LEAK TESTING OF THE RHR AND UHI SYSTEMS SEQUOYAH NUCLEAR PLANT UNITS 1 AND 2

s ENCLOSURE REQUEST FOR EXEMPTION FROM APPENDIX J LEAK TESTING OF THE RHR AND UHI SYSTEMS BACKGROUND As part of the activity undertaken by TVA to close out unresolved items 50-327/86-20-09 and 50-328/86-20-09, which were identified in IE Inspection Report Nos. 50-327/86-20 and 50-328/86-20, as transmitted from J. A. 01shinski to S. A. White by letter dated April 23, 1986, remote manual valves in both the residual heat removal (RHR) and upper head injection.(UNI) lines have been redesignated containment isolation valves. Also in support of- the close out of the unresolved items 50-327/86-20-09 and 50-328/86-20-09, the pressure relief valves in the overpressurization protection piping for the safety injection system, chemical and volume control system (CVCS), and containment spray system have been redesignated as outboard containment isolation valves.

The valves in the RHR, UNI, and pressure relief lines have been evaluated with-respect to testing requirements for containment isolation valves as identified in 10 CFR 50 Appendix J. As a' result of the evaluation, it has been determined that a type C leak rate test cannot be performed with either the b RHR or UHI systems, or the pressure relief piping, as currently configured.

I However, the evaluation also provided sufficient justification for requesting an exemption under 10 CFR 50.12 from performing type C leak testing for those systems and pressure relief valves. A summary of the evaluations and the basis for requesting the subject exemption from type C leak testing follows.

SYSTEMS EVALUATIONS A summary of the evaluation of the redesignated containment isolation valves in the RHR and UHI systems and the pressure rollef lines with respect to the requirements of 10 CFR 50 Appendix J is presented in this section.

RHR System With both RHR pumps operating, a water seal in the injection line penetrations i is provided that guarantees a 30-day water supply _and an injection pressure greater than 1.1 Pa. Thus, for the injection case with both RHR pumps running, these lines are not subject to type C leak rate testing.

With a single active failure of an RHR pump, however, the water seal will not be maintained on the associated penetration during the recirculation mode

, following a hypothetical loss of coolant accident (LOCA).

However, any leakage past the primary and secondary check valves and the

! remote manual valve would be into a seismically qualified closed system of safety system grade piping. (Both the primary and secondary check valves are

leak tested with water as pressure isolation valves to a requirement of less than or equal to 1 gpm at a nominal RCS pressure of 2,235 psig.)

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4 The piping outside containment meets the requirements for a closed system outside containment as presented in section 6.2.4 of the FSAR. There is testing performed which verifles integrity of this piping. This testing includes annual inspections in accordance with NUREG-0737 position III.D.1.1, inservice pressure testing in accordance with ASME Section XI, and quarterly ASME Section XI pump tests. As the RHR system is a dual purpose system used during normal operation, an additional opportunity is provided to verify system integrity.

UHI System The UHI system is normally filled with water from the accumulator up to the primary check valves going into the reactor head. The differential pressure between the RCS and the UHI system keeps the check valves closed during normal operation. Valves 87-21 and 87-23, as well as 87-22 and 87-24, are open during normal reactor operation, providing for immediate availability of the UHI system fluid when it is needed under accident conditions. When the RCS pressure falls below approximately 1,200 psig, the UHI system begins to discharge into the reactor. When the accumulator reaches low level valves 87-21 and 87-23 (as well as 87-22 and 87-24) close, retaining a water seal with pressure much greater than 1.1 Pa on the outboard side of these valves.

This water seal and pressure is maintained by the remaining water level in the UHI accumulator and the pressure acting upon this water head from the UHI gas accumulator (nitrogen blanket). If for some unexpected reason residual pressure in the UHI system decreases, the pressure would, at worst, equalize with pressure inside containment. Any leakage of containment atmosphere through valves 87-21, 87-22, 87-23, or 87-24 into the UHI system volume would be contained by the closed, seismically qualified, TVA Class B system outside containment.

Valves 87-10 and 87-11, identified as containment isolation valves in the Sequoyah technical specifications, are located in a test line outside containment. These valves are closed during normal reactor operation and receive a phase A Containment Isolation signal. It is possible to postulate a leak path of containment atmosphere to the floor drain collector tank through valves 87-10 and 87-11 in the excontainment test line. There are no manual or remote-manual block valves currently installed within the UHI system that will allow type C leak rate testing of these valves. However, TVA proposes to perform a type C leak rate test of these two valves with the pressure applied in the opposite direction of the containment pressure that would be experienced as a result of a postulated event that would actuate the UHI system. This test would provide assurance that valves 87-10 and 87-11 provide a seal.

Pressure Relief Piping Pressure relief is provided for the safety injection system, chemical and volume control system (CVCS), and containment spray system by means of vent lines running to a common line outside containment. The common line then passes through containment penetration X-24 and exhausts into the pressurizer

4 relief tank (PRT) inside containment. Containment isolation is accomplished by a single check valve in the common line inside containment, and a pressure relief valve in each individual vent line. Each of the systems for which pressure relief is provided is a closed seismically qualified TVA class B system.

For the safety injection lines, the Sequoyah plant-specific Emergency Operating Instructions (E0Is) require the centrifugal charging pumps to operate continuously. This action provides a water seal on pressure relief valves in the lines with a guaranteed 30-day water supply at an injection pressure greater than 1.1 Pa. Thus, the pressure relief valves in the safety injection lines are not subject to type C leak rate testing.

In general, however, type C leak rate testing cannot presently be performed for the valves in the line associated with penetration X-024. There are no manual or remote-manual block valves in the line that would allow such testing of those relief valves. Furthermore, ASME Section III, Class 2, NC-3677.3, states that there chall be no intervening stop valves between pressure relief valves and their relief points to ensure those lines cannot be inadvertently isolated. However, any throughline leakage that may occur through the pressure relief valves would be contained within a closed seismically qualified TVA class B system outside containment. Also, the containment pressure would tend to operate to further ensure the check valve and pressure relief valves would seat tightly.

Explanation of TVA Class B System TVA Class B designation means the valves and piping are ASME Section III Class 2, Seismic Category I or equivalent. Valves and piping procurred before April 1973 are designed in accordance with ANSI Standard B 16.5 and B 31.1, respectively, as opposed to Section III of the ASME Code.

The valves in the RHR and UHI systems now designated as containment isolation valves, and associated piping, have been purchased to TVA Class B requirements.

BASIS FOR EKEMPTION The bases for applying for an exemption from the requirements of Appendix J leak rate testing of the respecified containment isolation valves in the RHR and UHI lines are given in this section.

RHR System As noted in the description of the RHR system provided earlier, there is a combination of a water seal system, a qualified closed system outside containment that would contain any unexpected leakage of containment

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atmosphere, and an inspection and test program to verify system integrity.

These features ensure the safe operation of the RHR system. Also, to modify the RHR system to allow Appendix J leak rate testing would result in increased capital cost of the' plant and radiation exposure to the modifications crew.

Thus, an exemption from the requirements of 10 CFR 50 Appendix J should be granted in accordance with 10 CFR 50.12(a)(2)(iii) and 10 CFR 50.12(a)(2)(vi).

UHI System The description of the UHI system identified the combination of a water seal system, a qualified closed system outside of containment that would contain any unexpected leakage of containment atmosphere, and a test program to verify system integrity. These features ensure the safe operation of the UHI system. Also, to modify the UHI system to allow Appendix J leak rate testing would result in increased capital cost of the plant and radiation exposure to the modifications crew. Furthermore, it is TVA's intent to remove the UHI system from Sequoyah. Thus, an exemption from the requirements of 10 CFR 50 Appendix J should be granted in accordance with 10 CFR 50.12(a)(2)(iii),

10 CFR 50.12(a)(2)(v), and 10 CFR 50.12(a)(2)(vi).

pressure Relief piping The description of the pressure relief piping identified that the ASME Code Section III, Class 2. NC-3677.3 states that there shall be no intervening stop valves between tressure relief valves and their relief points so as to ensure those lines cannot be inadvertently isolated. To modify the piping to allow 10 CFR 50 Appendix J 1eak rate testing would violate the ASMR Code.

Furthermore, any. unexpected leakage that may occur would be contained within a qualified closed system outside containment. Also, to modify the pressure relief piping to allow for Appendix J leak rate testing would result in increased capital cost of the plant and radiation exposure to the modifications crew. Thus, an exemption from the requirements of 10 CFR 50 Appendix J should be granted in accordance with 10 CFR 50.12(a)(2)(i),

10 CFR 50.12(a)(2)(iii), and 10 CFR 50.12(a)(2)(iv).

ENVIRONMENTAL IMPACT EVALUATION In addition to a water seal, a qualified closed system outside containment is provided for containing any unexpected leakage of containment atmosphere into the RHR and UHI systems foll"ving a postulated LOCA. Also, testing of two valves on UHI test lines will ensure the integrity of the seal provided by those valves. For the pressure relief lines, the action of the containment air would act to ' further seat the pressure relief valves and any unexpected leakage of containment atmosphere would again be contained by qualified closed systems outside of containment. Thus, it is concluded that the granting of an exemption from 10 CFR 50 Appendix J 1eak rate testing will not adversely impset the environment.

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SUMMARY

Based on the descriptions for the RHR, UNI, and pressure relief piping systems, and the discussion of the bases for granting exemptions from 10 CFR 50 Appendix J leak rate testing, it is our conclusion that the requested exemptions are authorized by law, will not present undue risk to the public health and safety, and are consistent with the common defense and security.

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