ML20024G359

Request for Exemption from Certain Requirements of 10CFR50, App J, Primary Reactor Containment Leakage Testing for Water-Cooled Power Reactors

ML20024G359
Person / Time
Site:	Monticello
Issue date:	05/05/1976
From:	Wachter L NORTHERN STATES POWER CO.
To:
Shared Package
ML20024G357	List: ML20024G356 ML20024G359
References
A00L-760505, AL-760505, NUDOCS 9102110365
Download: ML20024G359 (12)

Text

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4 UNITED STATES NGCLEAR REGULATORY COMMISSION NORDIERN STATES POWER COMPANY MONTICELLO NUCLEAR GENERATING PLANT i

Docket No. 50-263 License No. DPR-22 Request for Exemption from Certain Requirements of 10CFR50, Appendix J, " Primary Reactor Containment Leakage Testing for Water-Cooled Power Reactors" Northern States Power Company, a Minnesota corporation,- by_ this letter dated May 5,1976 -hereby submits a request for exeaption from a number of require-ments of 10CFR50, Appendix J.

This request is made in-accordance with Section 50.12 of 10CFRSC.

This request contains no restricted or other defense information.

NORTHERN STATES POWER COMPANY By d M dmo-L JAFachter

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Vice President, Power Ptsduction

& System Operation On this 5th day of May,1976, before me a notary public in and for said County,

_ personally appeared _ L J Wachter, Vicu President, Power Production ard System Operation, ~and being first duly sworn acknculedged that he is authorized to execute this docunent on behalf of Northern States Power Company, that he

- knows the contents thereof and that to the best of his knowledge, informa tion and belief, the statements made in it are rue and that it is not interposed for delay. _

AMD AAb'

'#'S DENISE E. BRANAll l7 WM Puntsc ~ mnnon -

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l MONTICELLO NUCLEAR GENERATING PLANT DOCKET No. 50-263 May 5, 1976 REQUEST FOR EXEMPTION FRCH CERTAIN REQUIREMENTS OF 10CFR50, APPENDIX J Pursusnt to 10CFR50.12, the holders of Provisional Operating License DPR-22 hereby request the following exemptions from the requirements of Appendix J to 10CFR50, 1.

Appendix J Section III. B.1, Type B Testing of Instrument Lines Exemption Requested Section III.B.1, under the definition contained in Section II.G.4, can be con-strued to require testing of inst rument lines not equipped with excess flow check valves.

No provision for testing these instrument lines was provided in the original plant design.

We ask exemption from this requirement.

The affected penetrations are:

X-29E Drywell Pressure Sensing Line X-29F Drywell Pressure Sensing Line X-32C Drywell Ficod Level Switch Tap X-50E Drywell Pressure Sensing Line X-50F Drywell Pressure Sensing Line X-206A - X-206D Torus Instrumentation X-209A - X-209D Torus Instrumentation

Reason for Request

These instrument penetrations are required to sense drywc11 and torus pressure, temperature, and water level. The small diameter instrument piping outside containment connects to a scaled transducer.

In the case of the pressure instruments, safeguard signals are generated.

There is no practicable method of testing these penetrations using Type B testing.

Each penetration is tested as part of the Type A test program.

The probability of rupture of an associated instrument line outside containment and the resulting leakage to the environs of the post accident containment gaseous atmosphere is low. Manual isolation valves are provided to isolate a Icaking instrument.

Any addition or modification (such as isolation velves) to permit testing these penetrations could result in a degradation in performance of their safety related function.

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Appendix J Section III.B.2, Type B Test Pressure for Drywell Air Lock Exemption Requested This section requires all Type B tests to be conducted at Pa (41 psig).

We request exemption from this requirement in the case of the drywell air lock.

We ask that we be permitted to use the current 10 psig air lock test pressure specified in the Monticello Technical Specifications.

Reason for Request

The Monticello drywell air lock utilitee two heavy steel single-gasketed doors designed to seal with pressure applied frem the drywell side.

The only method available to leakage test the air lock is to pressurize the volume between the inner and cuter doors.

This requires installing temporary bracing on the inner door to assist in holding it closed (test pressure tends to open the door).

We believe that 10 psig is a test pressure which permits a valid and safe test to be performed.

Increasing the test pressure to 41 psig increases the force on the inner door thereby reducing the design margin of the temporary bracing. The higher test pressure also leads to an artificially high measured leakage due to increased leakage past the inner door.

3.

Appendix J Section III.C.1. Type C Testing of Torus Spray Valves Exemption Requested Section III.C.1, under the definition contained in Section II.H.3, can be con-strued to require testing of the Loop A and Loop B Suppression Chamber Spray valves (Figure 1).

No provision for conducting local leakage tests was provided in the original plant design.

We request that these valves be excluded from Type C testing.

Reason for Request

These valves are normally closed, remote-manual motor operated valves.

They can be intermittently opened by the Control Room Operator to reduce the temperature and pressure in the torus during the latter stages of a loss of coolant accident.

Both valves are located outside of containment.

These lines would be pressurized by the RHR pumps during all stages of the accident. This pressure is well above the peak suppression chamber pressure following a loss of coolant accident preventing any outleckage of the sup-pression chamber gaseous atmosphere.

There is no single active failure which could prevent pressurization of these lines by the RIIR pumps.

Since the Torus Spray lines cannot constitute a containment Icakage path, testing of the isolation valves in these lines is unnecessary.

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4. Appendix J.Section III.C.1, Direction of Test Pressure

_ Exemption Reques ted This section requires that test pressure for Type C testing be applied in the same direction as that when the valve would be required to perform its safety related function, unless it can be determined that the results from the t ests for a pressure applied in a different direction will provide equivalent or more conservative results.

We request that we be permitted to test all of the following penetrations, except X-39A and X-39B, with test pressure in the reverue direction.

There is no Provision for testing these penetrations in the correct direction.

We request that we be exempted fran the requirement to test penetrations X-39A and X-39B.

Penetration No.

Description of Service Type Valve X-18 Floor Drain Sump Globe X-19 Equipment Drain Sump Globe X-25 Drywell Ventilation Butterfly X-26 Drywell Ventilation Butterfly X-27D - X-27F 0xygen Analyzer Globe X-39A Drywell Spray Gate - Wedge Type X-39B Drywell Spray Gate - Wedge Type X-41 Coolant Sample Globe X-48 Nitrogen Pumpback Globe X-205 Torus ventilation Butterfly X-214 0xygen Analyzer Globe X-220 0xygen Analyzer Globe

Reason for Request

Test connections at Monticello have generally been provided in the connecting volume between the inboard and outboard isolation valves.

The connecting volume is pressurized and the pressure decay rate is measured. These penetrations have no other provision for testing the inboard isolation valve.

In this test the inboard valve is pressurized in a direction opposite to the pressure it would experience following an accident.

Except for penetrations X-39A and X-39B, testing of these valves in the reverse direction is permissible under the provisions of Section XI, Subsection IWV, of the ASME Code.

In these cases the leak tightness of the valve is not dependent upon direction of pressurization.

The valves in penetrations X-39A and X-39B are normally closed, remote-manual motor operated valves.

They can be intermittently opened by the Control Room Operator to reduce the Temperature and pressure in the drywell during the later stages of a loss of coolant accident. X-39A and X-39B would be pressurized by the RHR pumps during all stages of the accident.

This pressure is well above the peak drywell accident pressure preventing any outleakage of the drywell gaseous a tmosphere.

There is no single active failure which could prevent pressurization of these lines.

Since these lines cannot constitute a containment leakage path, testing of the isolation valves in these lines is unnecessary (Figure 2).

5.

Appendix J Section III.C.1, Type C Testing of Core Spray Testat le Check Valves Exemption Requested Section III.C.1, under the definition contained in Section II.H.3, can be construed to require testing of the Loop A and Loop B Core Spray Testable Check valves (Fig are 3).

We request that these valves be excluded f rom Type C testing and that the two motor operated gate valves in each line located outside containment be subjected to Type C testing in their place.

Reason for Request

The testable check valve in each Core Spray line was not intended to meet gas leakage acceptance criteria. These valves exhibit moderate leakage when re-quired to seal against a low pressure gas, but are leak tight in their normal environment.

These valves consistently fail to meet the individual valve Tech-nical Specification maximum allowable leakage rate. Maintenance performed on them to meet the criteria applied to containment isolation valves involves many hours of work in an area where high radiation and contamination levels prevail. Any Dmprovement in leak tightness is temporary.

In the event of a loss of coolant accident combined vidi a failure of one core spray pump to start, the potential exists for containment leakage to pass through the Core Spray line associated with the non-operating loop.

Barriers to this leakage include the testable check valve located inside containment and two motor operated remote-manual valves located outside containment.

In the event of a failure of a Core Spray pump, the tuo motor operated valves could be closed to eliminate this potential leakage path.

Provisions have been provided in the original plant design to test the two motor operated valves in each Core Spray line.

This testing would be conducted in accordance with Appendix J.

All components of the Core Spray System are protected from seismic events and potential missiles.

Failure of bo'h motor operated gate valves located outside containment in each Core Spray line is highly bnprobable.

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6. Appendix J Section III.C.1, Type C Testing of Low Pressure Coolant Injection Testable check Valves Exemption Requested Section III.C.1, under the definition contained in Section II.H.3, can be con-strued to require testing of the Loop A and Loop B Low Pressure Coolant Injection (LPCI) testable check valves (Figure 4).

We request that these valves be excluded from Type C testing and that the two motor operated gate valves in each line located outside containment be subjected to Type C testing in their place.

Reason for Request

The testable check valve in each LPCI supply line was not intended to meet gas leakage acceptance criteria. These valves exhibit moderate leakage when required to seal against a low pressure gas, but are leak tight in their normal environment. These valves consistently fail to meet the individual valve Technical Specification maximum allowable leakage rate. Maintenance performed on them to enable them to meet the criteria applied to containment isolation valves involves umny hours of work in an area where high rndiation and contamination levels prevail. Any improvement in leak tightness is temporary.

These lines would be pressurized by the RHR pumps in the post accident condition and would supply LPCI flow to the recirculation loops.

There is no single active failure which could prevent pressurization of these lines above the calculated peak contain-ment pressure.

It may be necessary, however, in the long t rm period following an accident to isolate an RHR loop to perform maintenance.

Under these conditions, the barriers to contain-leakage include the testable check valve located inside containment and two motor ment operated remote-manual (for containment isolation purposes) valves located outside con-tainment. The two motor operated valves are closed to eliminate a potential Icakage path in this situa tion.

Provisions have been provided in the original plant design to test the two motor operated valves in each LPCI supply line.

This testing would be conducted in accord-ance with Appendix J.

All components of the RHR System are protected from seismic events and potential missiles. Failure of both motor operated valves located outside containment in each LPCI supply line is highly hnprobable.

'7.

Appendix 3 Section III.C.2. Type C Test Pressure for Main Steam Isolation Valves Exemption Requested Section III.C.2 requires all Type C tests to be conducted at Pa (41 psig).

We request exemption from this requirement in the case of the Main Steam Isolation Valves (MSIV's).

We ask that we be permitted to use the current 25 poig MSIV test pressure specified in the Monticello Technical Specifications.

1 Reason for Request

Main Steam Isolation Valves are normally tested each refueling outage. After the vessel head has been removed, these valves must be tested by pressurizing the connecting volume between the two valves in each line (Figure 4).

The inboard Main Steam isolation valve is subjected to test pressure in a direction that is opposite to that existing following an accident.

During testing, test pressure tends to unseat the valve and can lead to an invalid measurement.

For this reason, the test pressure has been limited to 25 psig for main steam isolation valve testing and the allowable leakage has been stated in terms of a 25 psig test pressure in the current Technical Specifications.

8.

Appendix J Section III.D.2, Frequency of Drywell Air Lock Testing Exemption Requested Section 111.D.2 requires that air locks shall be tested each six months or after each opening, whichever occurs first.

We request that an exemption be granted f rom the requirement to conduct a Type B test of the air lock af ter each opening.

We ask that we be permitted to perform this testing every three days ducing periods the drywell air lock is in use while contain-ment integrity is required.

Reason for Exemption The Monticello air lock does not have double-gasketed door seals. All leakage tests be conducted by pressurizing the space between the inner and outer doors.

This must test requires at least four hours to perform.

Overall pressure testing of the air lock every three days is a reasonable surveillance requirement to verify leak tightness when the air lock is actually in use.

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