ML17332A386

Safety Evaluation Supporting Amends 185 & 170 to Licenses DPR-58 & DPR-74,respectively

ML17332A386
Person / Time
Site:	Cook
Issue date:	11/08/1994
From:	Office of Nuclear Reactor Regulation
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ML17332A385	List: ML17332A383 ML17332A386
References
NUDOCS 9411140206
Download: ML17332A386 (8)

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UNITED STATES NUCLEAR REGULATORY COMIVIISSION WASHINGTON, O.C. 20555-0001 SAFETY EVALUATION BY THE OFFICE OF NUCL AR REACTOR R

GU ATION RELATED TO AMENDMENT NO.

TO FACILITY OPERATING LICENSE NO. DPR-58 AND AMENDMENT NO. 170 TO FACILITY OPERATING LICENSE NO.

DPR-74 INDIANA MICHIGAN POWER COMPANY DONALD C.

COOK NUCLEAR PLANT UNIT NOS.

1 AND 2 DOCKET NOS.

50-315 AND 50-316

1.0 INTRODUCTION

By letter dated December 22, 1993, the Indiana Michigan Power Company (the licensee) requested amendments to the Technical Specifications (TS) appended to Facility Operating License Nos.

DPR-58 and DPR-74 for the Donald C.

Cook Nuclear Plant, Unit Nos.

1 and 2.

The proposed amendments would revise the action statement in TS 3.7. 1.5, Steam Generator Stop Valves, to be more consistent with NUREG-1431, "Standard Technical Specifications Westinghouse Plants'

The proposed changes will allow both greater time for compensatory action as well as operation in Modes 2 and 3 with valves inoperable but closed.

In addition, a Unit 2 action requirement would be revised to be consistent with Unit 1 and fulfill a Licensee Event Report commitment, 2.0 EVALUATION The steam generator stop valves (SGSVs),

also referred to as main steam isolation valves (MSIVs), isolate steam flow from the secondary side of the steam generators following a high energy line break.

SGSV closure terminates flow from the unaffected (intact) steam generators.

One SGSV is located in each main line outside, but close to, containment.

The SGSVs are downstream from the main steam safety valves (MSSV) and auxiliary feedwater pump turbine (AFW) steam supply, to prevent MSSV and AFW isolation from the steam generators by SGSV closure.

Closing the SGSVs isolates the turbine, steam bypass

system, and other auxiliary steam supplies from the steam generators.

The SGSVs close on a main steam isolation signal generated by either low steam generator pressure or high containment pressure.

The SGSVs fail closed on loss of control or actuation power.

The SGSVs may also be manually actuated.

The design basis of the SGSVs is established by the containment analysis for the large steam line break inside containment'he design precludes the blowdown of more than one steam generator, assuming a single active component failure (e.g., the failure of one SGSV to close on demand).

The SGSVs serve only a safety function and remain open during power operation.

These valves operate under the following situations:

94ii140206 94ii08 PDR ADOCK 050003i5 P

PDR

I a.

A high energy line break inside containment which assumes that the SGSV on the affected steam generator remains open to maximize the mass and energy release into containment.

Steam is discharged from all steam generators until the remaining SGSVs close.

After SGSV closure, steam is,discharged into containment only from the affected steam generator and from the residual steam in the main steam header downstream of the closed SGSVs in the unaffected loops.

Closure of the SGSVs isolates the break from the unaffected steam generators.

b.

A break outside of containment and upstream from the SGSVs which is not a

containment pressurization concern.

The uncontrolled blowdown of more than one steam generator must be prevented to limit the potential for uncontrolled reactor coolant system cooldown and positive reactivity addition.

Closure of the SGSVs isolates the break and limits the blowdown to a single steam generator.

c.

A break downstream of the SGSVs will be isolated by the closure of the SGSVs.

d.

Following a steam generator tube rupture, closure of the SGSVs the:ruptured steam generator from the intact steam generators.

add%ion to minimizing radiological releases, this enables the maintain the pressure of the steam generator with the ruptured the SGSV setpoints, a necessary step toward isolating the flow rupture.

isolates In operator to tube below through the e., The SGSVs are also utilized during other events such as a feedwater line break.

The Cook SGSV design incorporates a piston which is attached to the valve's stem.

The steam above and below the piston is normally at line pressure.

The cylinder volume above the piston is piped through a three-way valve into a pair of redundant, air-operated dump valves.

Upon receipt of a signal to

close, the dump valves open and vent the steam from the cylinder.

The steam pressure in the valve's body below the piston forces the piston to move rapidly and close the valve.

The valve therefore is not dependent on an external power source for emergency closure.

Each valve closes within 5 seconds after r eceipt of the requisite safety signal.

Speed of closing is controlled by the setting of a needle restrictor within the hydraulic opening and closing system.

The Cook Ste'am Generator Stop Valves TS requires each steam generator stop valve to 'be operable.

In Node I, when a valve is inoperable but open, the requi red action is to restore the valve within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />, otherwise reduce power to less tlhan 5X within the next 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />.

The licensee has proposed to change the action times to 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> and 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />, respectively.

In Nodes 2 and 3, the current a+quired action is to maintain an inoperable stop valve closed, or be in hot s'hutdown within the next 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.

The licensee has proposed to change the action to direct closure of one or more inoperable valves within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> and to verify closure once per 7 days.

Alternatively, be in Node 4 within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and Node 3 within the first 6.

The licensee has also proposed to change the Unit 2 surveillance requirement such that a timed closure to demonstrate operabi1ity is required only for valves which are open.

The proposed change to the Node 1 action statement is consistent with the "Standard Technical Specifications Westinghouse Plants" (WSTS),

NUREG-1431, September 1992.

In support of the action requirements in the WSTS, the staff stated:

"The 8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> Completion Time is reasonable, considering the low probability of an accident occurring during this time period that would require a

closure of the NSIVs.

The 8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> Completion Time is greater than that normally allowed for containment isolation valves because the HSIVs are valves that isolate a closed system penetrating containment.

These valves differ from other containment isolation valves in that the closed system provides an additional means for containment isolation.

If the NSIV cannot be restored to OPERABLE status within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />, the unit must be placed in a

MODE in which the LCO does not apply.

To achieve this

status, the unit must be placed in NODE 2 within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />, at which point the action statement for NODES 2 and 3, discussed below, would be entered.

The Completion Times are reasonable, based on operating experience, to reach MODE 2 and to close the HSIVs in an orderly manner and without challenging unit systems."

Based on the above, the proposed changes to the Mode 1 action statements are acceptable.

The new proposed action statement for Nodes 2 and 3 is consistent with the "Standard Technical Specifications Westinghouse Plants" (WSTS),

NUREG-1431, September 1992.

In support of the action requirements in the WSTS the staff stated:

"Since the HSIVs are required to be OPERABLE in MODES 2 and 3, the inoperable HSIVs may either be restored to OPERABLE status or closed.

When closed, the HSIVs are already in the position required by the assumptions in the safety analysis.

The 8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> Completion Time is consistent with that allowed in Condition A (corresponding to the Node 1

action statement).

For inoperable NSIVs that cannot be restored to OPERABLE status within the specified Completion Time, but are closed, the inoperable HSIVs must be verified on a periodic basis to be closed.

This is necessary to ensure that the assumptions in the safety analysis remain valid.

The 7 day Completion Time is reasonable, based on engineering judgement, in view of HSIV status indications available in the control

room, and other administrative controls, to ensure that these valves are in the closed position."

Based on the above, the proposed changes to the Modes 2 and 3 action statements are acceptable.

Appropriate changes are also proposed for the Bases to provide the rationale behind the revised action statements.

These changes are acceptable.

The proposed change to the Unit 2 surveillance requirement, to specifically state that a timed closure to demonstrate operability is required only for valves which are open, is intended to clarify the surveillance requirement and

1

4 make it consistent with the Unit 1 TS.

Surveillance requirement (SR) 4.7. 1.5. 1 currently states:

"Each steam generator stop valve shall be demonstrated OPERABLE by verifying full closure within 8 seconds when tested pursuant to Specification 4.0.5."

SR 4.0.5 states in part:

"Surveillance Requirements for inservice inspection and testing of ASIDE Code Class 1, 2, and 3 components shall be applicable as follows:

a.

Inservice inspection of ASME Code Class 1, 2, and 3 components and inservice testing of ASME Code Class 1, 2, and 3 pumps and valves shall be performed in accordance with Section XI of the ASIDE Boiler and Pressure Vessel Code and applicable Addenda as required by 10 CFR 50, Section 50.55a(g),

except where specific written relief has been granted by the Commission pursuant to 10 CFR 50, Section 50.55a(g)(6)(i)."

ASHE Code IWV-3416 states:

"For a valve in a system declared inoperable or not required to be operable, the exercising test schedule need not be followed.

Within 30 days prior to return of the system to operable

status, the valves shall be exercised and the schedule resumed in accordance with requirements of this article."

In the Cook TS, the limiting condition for operation for the SGSVs in Node 1

only requires action if an SGSV is inoperable but open and in Nodes 2 and 3

allows continued operation if the SGSV is maintained closed.

As a result, a

closed SGSV is not considered operable and therefore, would not need to be exercised.

However, in November

1992, due to the wording of SR 4.7, 1.5, 1 which states "Each steam generator stop valve shall be demonstrated OPERABLE..."

without regard for whether the SGSV is open or not, operations personnel at Cook concluded that a surveillance was overdue on a

SGSV which was closed.

After a review of the ASME Code, both the licensee and NRC staff concluded that no surveillance was required on a valve which is closed.

Therefore, the licensee has proposed to modify the surveillance that the operability demonstration is only required on SGSVs that are open.

Based on the above, the staff finds the proposed change acceptable.

3 '

STATE CONSULTATION In accordance with the Commission's regulations, the Michigan State official was notified of the proposed issuance of the amendments.

The State official had no comments.

4.0 ENVIRONMENTAL CONSIDERATION

The amendments change the requirements with respect to the installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20.

The staff has determined that the amendments involve no significant increase in the amounts, and no significant change in the types, of any effluents that may be released offsite, and that there is no significant increase in individual or cumulative occupational radiation

' ~.

exposure.

The Commission has previously issued a proposed finding that the amendments involve no significant hazards consideration and there has been no public comment on such finding (59 FR 4939).

Accordingly, the amendments meet the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9).

Pursuant to 10 CFR 51.22(b),

no environmental impact statement or environmental assessment need be prepared in connection with the issuance of the amendments.

5.0 CONCLUSION

The staff has concluded, based on the considerations discussed above, that:

(1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed

manner, (2) such activities will be conducted in compliance with the Commission's regulations, and (3) the issuance of the amendments will not be inimical to the common defense and security or to the health and safety of the public.

Principal Contributor:

John B. Hickman, NRR Date:

November 8, 1994

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