ML20196C332

Proposed Tech Specs,Adding Footnote to Spec 3.4.2 for RCS Safety Valves

ML20196C332
Person / Time
Site:	Sequoyah
Issue date:	12/06/1988
From:	TENNESSEE VALLEY AUTHORITY
To:
Shared Package
ML20196C330	List: ML20196C327 ML20196C332
References
NUDOCS 8812070257
Download: ML20196C332 (8)

Text

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a ENCLOSURE 1 PROPOSED TECHNICAL SPECIFICATION CHANGE SEQUOYAH NUCLEAR PLANT UNITS 1 Ah3 2 j i DOCKET NOS. 50-327 AND 50-328 4

(TVA-5QN-TS-88-26) 1 LIST OF AFFECTED PAGES Unit 1 3/4 4 ,3

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.i REACTOR COOLANT SYSTEM 3/4.4.2 SAFETY VALVES - SHUTDOWN {

LIMITING CON 0! TION FOR OPERATION 3.4.2 A minimum of one pressurizer code safety valve shall be OPERA 8LE with a lif t setting of 2485 PSIG + 1%.*

APPLICABILITY: MODES 4 and 5. . .<

ACTION:

With no pressurizer code safety valve OPERA 8LE, immediately suspend all opera-tions involving positive reactivity cha.nges and place an OPERABLE RHR loop into 4 j operation in the shutdown cooling mode. l.:

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$URVEILLANCE REQUIREMENTS

• I 4.4.2 No additional Surveillance Requirements other than those required by ,

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6 REACTOR COOLANT SYSTEM 3/4.4.2 SAFETY VALVES - $HUTDOWN LIMITING CONDIT!ON FOR bpERATION 3.4.2 A minimum of one pressurizer code safety. valve shall be OPERABLE with a lift setting of 2485 PSIG 2 1 *. ,

• APPLICABIL!TY: F0 DES 4 and 5. .

ACTION:

With no pressurizer code safety valve OPERABLE, immediately suspend all operations involving positive reactivity changes and place an OPERABLE residual heat removal loop into operation in the shutdown cooling mode. '

SUh!!LLANCE RE0u!REYENTS 4.4.2 No additional Surveillance Requirements other than those required by Soecifiention 4.0.5.

'Ine lift setting pressure shall correspond to ambient conditions of the valve at nominal operating temperature and pressure.

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• e ENCLOSURE 2 PROPOSED TECHNICAL SPECIFICATION CHANGE SEQUOYAH NUCLEAR PLANT UNITS 1 AND 2 DOCKET NOS. 50-327 AND 50-328 (TVA-SQN-TS-88-26) ,

I DESCRIPTION AND JUSTIFICATION FOR FOOTNOTE I

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a ENCLOSURE 2 e

Description of Change Tennessee Valley Authority proposes to modify the Sequoyah Nuclear Plant (SQN) units 1 and 2 technical specifications to add a footnote to limiting condition for operation (LCO) 3.4.2 for the reactor coolant system (RCS) safety valves. The footnote allows all three safety valves to be tested at the same time provided the valves are removed and the hole in the system is covered by a non-pressure-retaining membrane.

Reason for Change LCO 3.4.2 requires at least one pressurizer code safety valve to be operable during modes 4 and 5 (shutdown conditions). The basis for this requirement ensures adequate relief capacity for any overpressure condition that could occur during shutdown. However, the actual wording of the LCO prevents full valve testing if all three valves are to be tested at the same time.

American Society of Mechanical Engineers' (ASME) Code, section XI.

requires class 1 pressure relief valves to be tested according to the following table:

TABLE 1 CLASS 1 - PRESSURE RELIEF VALVE TESTING SCHEDULES. 5-YEAR PERIOD Minimum Camulative Percent of Valvea of Each Type and Time Period Manufacture to Be Tested Startup - 12 months 0 13 months - 24 months 25 25 months - 36 months 50 37 months - 48 months 73 49 months - 60 months 100 l

NOTE: No maximum limit is specified for valve tests within any specific time period of the above table; hewever, a minimum of 20 percent of the valves of each type and manufacture shall be tested within any 24 months. This 20 percent shall be previously untested valves, if they exist.

During the subsequent 5-year period. 20 percent of the valves shall be tested within any 24 months. This 20 percent shall be previously untested i valves, if they exist. Should any valves fa.11 to meet the acceptance i criteria of the test, the remaining two valves must also be tested.

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The code also allows testing requirements to be satisfied by in.<talling a J partial or full complement of pretested valves to replace those valves that had been in service.

In the past. SQN has satisfied testing requirements by testing one valve (20 percent) and then testing the remaining two valves if the first valve failed. SQN ships the safety valves offsite for testing. If the first valve fails, the other two cannot be removed and shipped until the first valve is returned. installed and returned operable. The time window f or safety valve testing is usually very tight; therefore, tre time delays described above can potentially delay the outage. ,

Because of recent modification of the safety valves (replace water trim disc and nozzle with steam trim). replacement parts are available for full complement testing. The desired method for performing this test is to remove all three valves it. service and then install the replacement valves. The current LCO does not allow this, and scheduling problems are created that could add time to t.5e outage. Either way the valves are tasted (20-percent testing or full or partial complement testing), the need arises for all three safety valves to be removed at the same time.

However, this flexibility is prevented by the LCO.

Justification Tor Change The pressurizer safety valves are described in sections 5.1 and 5.2.2 of the Final Safety Analysis Report (FSAR). Pressure relief devices on the RCS are the three pressurizer safety valves and two pcwer-operated relief valves (72RVs). Other relief valves are connected to the primary side through auxiliary systems.

The sizing of the safety valves is based upon the positive aurge of the r actor coolant produced as a result of a turbine trip from full load, assuming the core continues to produce full power. .Gring low-temperature operation (less than 350 degrees Fahrenheit (F]). one PCRV is sufficient to mitigate the pressure excursions produced by anticipated mass and heat input transients. 3ecause LCO 3.4.2 is enly applicable during modes 4 and 5 (less than 350 degrees F), the safety valves are not the assumed pressure relief device as analyzed in the FSAR. A proposed technical specification change for low-temperature overpressure protection requires the PORVs te te operable during modes 4 and 5 and during mode 6 with the reactor vessel head on. Thus, onerability of the safety valves is act required during codes 4 and 5.

v ENCLOSURE 3 PROPOSED TECHNICAL SPECIFICATION CHANGE ,

SEQUOYAH NUCLEAR PLANT UNITS 1 AND 2 DOCKET NOS. 50-327 AND 50-328 (TVA-SQN-TS-88-26)

DETERMINATION OF NO SIGNIFICANT HAZARDS CONSIDERATIONS ,

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ENCLOSURE 3 Significant Hazards Evaluation TVA has evaluated the proposed technical specification change and has determined that it does not represent a significant hazards consideration based on criteria established in 10 CFR 50.9'(c).

4 Operation of SQN in accordance with the proposed amendnent will nott (1) Invol.ve a significant increa't: in the probability or consequences of an accident previously evaluateu. The intent of the LCO has not been '

changed. P essure relief capabilities for overpressure protection still exist. The proposed change simply allows for more efficient testing techniques.

(2) Create the possibility of a new or different kind of accident from any previously analyzed. No hardwa re changes or operating changes are being made. The valves will still be tested in accordance with ASME section XI.

(3) Involve a significant reduction in a margin of safety. The removal of all three safety valves at the same time does not reduce the pressure relief capabilities; thus, the margin of safety is not changed.

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