U-600619, Amend to Application for Ol,Changing Tech Specs 3/4.3.8 Turbine Overspeed Protection Sys & 3/4.7.6 Turbine Bypass Sys to Reduce Probability of Generating Turbine Missile

Amend to Application for Ol,Changing Tech Specs 3/4.3.8 Turbine Overspeed Protection Sys & 3/4.7.6 Turbine Bypass Sys to Reduce Probability of Generating Turbine Missile

ML20206P379
Person / Time
Site:	Clinton
Issue date:	06/30/1986
From:	Spangenberg F ILLINOIS POWER CO.
To:	Butler W Office of Nuclear Reactor Regulation
Shared Package
ML20206P385	List: ML20206P395 U-600619, Amend to Application for Ol,Changing Tech Specs 3/4.3.8 Turbine Overspeed Protection Sys & 3/4.7.6 Turbine Bypass Sys to Reduce Probability of Generating Turbine Missile
References
U-600619, NUDOCS 8607020113
Download: ML20206P379 (2)

Text

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1. U-600619 l

L30-86 (06-30 )-L 1A.120

/LLIN018 POWER COMPANY CLINTON POWER STATION. P.o. BOX 678. CLINTON, ILLINOIS 61727 June 30, 1986  ;

Docket No. 50-461 Director of Nuclear Reactor Regulation Attention: Dr. W. R. Butler,. Director BWR Project Directorate No. 4 Division of BWR Licensing U. S. Nuclear Regulatory Comaission Washington, DC 20555

Subject:

Clinton Power Station 1 Changes to Technical Specifications 3/4.3.8, 3/4.7.6 Turbine Overspeed Protection System, Turbine Bypass System

Dear Dr. Butler:

The purpose of this letter is to request changes in Clinton Power Station Technical Specification (CPS-TS) 3/4.3.8, " Turbine Overspeed Protection System" and 3/4.7.6 " Turbine Bypass System." Specification 3/4.3.8 contains surveillance requirements and a limiting condition for operation intended to reduce the probability of generating a turbine missile. Nuclear plants typically have this technical specification in order to reduce the risk of damage to safety related equipment from turbine missiles. However, analyses contained in the Clinton Final Safety Analysis Report (FSAR) demonstrate tuat the potential for damage to safety related equipment due to turbine missiles is acceptably low.

The turbine-generator orientation at CPS is favorable for reducing the probability of damage to safety related equipment from turbine missiles since all safety related components and structures are located in the axial direction from the turbine-generator (see FSAR Figure 3.5-1). Because of the turbine-generator location and orientation, safety related equipment lies outside the ~1ow trajectory turbine missile strike zone which is defined as the zone where objects may be subject to a direct strike from a turbine missile. Therefore, the only type of turbine missile that presents a hazard to CPS safety related equipment is a high trajectory missile, defined as a missile which initially travels upward and then can cause damage when falling.

CPS FSAR Section 3.5.1.3, using GE and NUREG-0800 ("USNRC Standard Review Plan," July 1981.) turbine failure data, indicates that the probability of damage from high trajectory turbine missiles is acceptably low. The probability of damage g safety related equipment based on GE turbine failure data is 1.05X10 per year fog one unit and based on NUREG-0800 turbine failure rate values is 7.5X10- per year for one unit. Using either GE or NUREG-0800 turbine failure rate data, the probabilityofdamagegosafety-relatedequipmentassociatedwiththis event is less than 10 per year, which the NRC considers an acceptable

! risk rate for the loss of an essential system from a single event.

0-8607020113 DR 860630 ~

ADOCK 05000461 PDR '

It is believed that the probability of damage to safety related equipment at Clinton Power Station from turbine generated missiles is acceptably low and therefore a technical specification exception to l Specification 3.0.4 is warranted. Illinois Power Company (IP) also recognizes that this exception has been granted to other recently licensed BWR's.

Specifications 3/4.3.8 and 3/4.7.6 require surveillance testing of the Main Turbine Control Valves (TCV's) and Main Turbine Bypass Valves (TBV's) at a frequency of once per seven (7) days in order to demonstrate operability. The General Electric Technical Information Letter (TIL) Number 969 and Service Information Letter (SIL) Number 413 confirm the excellent reliability of these valves and recommend a 31 day surveillcnce frequency. IP recognizes that this change has been approved for recently licensed BWR's and requests this change for the CPS-TS as indicated in the attached markup of the appropriate CPS-TS.

If you should have any questions or require additional information, please call me.

Sincerely yours, A ()

.M. 'qac4 F. A. pange erg Manager - Li ensing and Safety TLR/kaf Attachments cc: B. L. Siegel, Clinton Licensing Project Manager NRC Resident Office Regional Administrator, Region III, USNRC Illinois Department of Nuclear Safety

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