ML20213F292

Application for Amend to License NPF-42,revising Tech Spec Table 3.3-5 to Change ESF Response Times to Reflect Time Required to Transfer Charging Pump Suction from Rod Control Tank to Refueling Water Storage Tank.Fee Paid

ML20213F292
Person / Time
Site:	Wolf Creek
Issue date:	05/07/1987
From:	Bailey J WOLF CREEK NUCLEAR OPERATING CORP.
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
Shared Package
ML20213F294	List: ML20213F292 ML20213F300
References
ET-87-0180, ET-87-180, TAC-65318, NUDOCS 8705150282
Download: ML20213F292 (9)

Text

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WOLF CREEK NUCLEAR OPERATING CORPORATION May 7, 1987 U.S. Nuclear Regulatory Commission i

ATTN: Document Control Desk Washington, D.C. 20555 Letter: ET 87-0180 Re: Docket No. 50-482 Subj: Revision to Technical Specification Table 3.3 Engineered Safety Features Response Times Gentlemen:

The purpose of this letter is to transmit an application for amendment to Facility Operating License No. NPF-42 for Wolf Creek Generating Station, Unit No. 1. This license amendment request proposes revising Technical Specification Table 3.3-5 to change the Engineered Safety Feature (ESP) response times for items 2.a. (Containment Pressure-High-1, Safety Injection), 3.a. (Pressurizer Pressure-Low, Safety Injection), and 4.a.

(Steamline Pressure-Low, Safety Injection).

This application for amendment revises Technical Specification Table 3.3-5, ESF Response Times, to more accurately reflect the time required to transfer charging pump suction from the Volume Control Tank to the Refueling Water Storage Tank following a postulated steam line break event. A complete Safety Evaluation and Significant Hazards Consideration are provided as Attachments I and II respectively. The proposed changes to Technical Specification Table 3.3-5 and its associated Bases are provided in Attachment III.

In accordance with 10 CFR 50.91, a copy of this application for amendment, with attachments is being provided to the designated Kansas state official.

Enclosed is a check (No. 000124) for the $150.00 application fee required by 10 CFR 170.21.

370510028a 370D07 Oy gQ PDH P

ADOCK 0500048.

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\p PO. Bcx 411/ Burbngton, KS 66839 < Phone- (316) 364 8831 An Eau # Oppc<tumty Emgeyor M F HCVET

ET 87-0180 Page 2 May 7, 1987 The proposed revision to the Wolf Creek Generating Station Technical Specifications will be fully implemented within 30 days of formal Nuclear Regulatory Commission approval. If you have any questions concerning this matter, please contact me or Mr. O. L. Maynard of my staff.

Very truly yours,

' 47 V(L/ )

l John A. Bailey i Vice-President Engineering and Technical Services JAB:Jad Enclosure Attachments: I - Safety Evaluation II - Significant Hazards Consideration III - Proposed Technical Specification Changes cc: P0'Connor (2)

RMartin JCummins GAllen

STATE OF KANSAS )

) SS COUNTY OF COFFEY )

John A. Bailey, of lawful age, being first duly sworn upon oath says that he is Vice-President Engineering and Technical Services of Wolf Creek Nuclear Operating Corporation; that he has read the foregoing document and knows the content thereof; that he has executed that same for and on behalf of said Corporation with full power and authority to do so; and that the facts therein stated are true and correct to the best of his knowledge, information and belief.

, o John A. Bailey a

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JA Vice-President Engineering and i Technical Services SUBSCRIBED and sworn to before me this 7 day of M Q , 1987.

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. Notary Public

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II Expiration Date M Y /990

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ATTACHMENT I SAFETY EVALUATION

Attschment I'to ET 87-0180 Page 1 of 3

-Hay 7, 1987 SAFETY EVALUATION This ~ amendment request revises Wolf Creek Generating Station (WCGS), Unit No.1, Technical Specification Table 3.3-5, Engineered Safety Features (ESF)

Response Times for items 2.a . (Containment Pressure-High-1, Safety Injection), 3.a . (Pressurizer Pressure-Low, Safety Injection), and 4.a.

(Steam Line Pressure-Low, Safety Injection). -These changes are being made to more accurately reflect the time required to change charging pump suction from the Volume Control Tank (VCT) to the Refueling Water Storage Tank

( RWST) .

BACKGROUND b In the normal configuration of the Chemical and Volume Control System (CVCS), the charging pumps take suction from the Volume Control Tank. When a Safety Injection ("S") signal is generated from the protection logic, a sigtal is sent to start the high-head ch3rging pumps and to begin opening the Refueling Water Storage. Tank isolation valves, in order to align the _

borated water source for delivery to the Reactor Coolant System (RCS). Once the RWST isolation valves have repositioned and are indicated fully opened,

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the isolation valves on the VCT will begin to close. This sequential valve 1

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stroke time can be as long as 25 seconds. Since the VCT is pressurized, -it will be the. source of the Safety Injection (SI) flow .until the isolation valves are closed. This affects the time assumed at which the 2000 ppm borated water in the RWST is available to the suction of the charging pumps.

The Updated Safety Analysis Report (USAR) steam line break analysis which supports the current Technical Specifications (Table 3.3-5) assumes the-following delays for delivery of borated water to the RCS:

1. "S" signal generation (2 seconds)

2. Diesel start-including time to come up to speed (12 seconds)

3. Valve stroke times and pumps to full speed (10 seconds)

However, this assumes that the VCT and RWST isolation valves stroke simultaneously rather than sequentially. The valve interlock logic increases the delay time for the availability of borated water by 15 seconds (conservatively) to 27 seconds with offsite power and 39 seconds without offsite-power. The only transient impacted by the increased time delay is the steam line break event. No other Chapter 15 transient relies on short-term boration from the RWST to mitigate the event.

EVALUATION Based on the current steam line break analysis for the Wolf Creek Generating Station (WCGS) and sensitivities performed for other plants, the additional time celay is acceptable. Specifically:

1) The additional delay in the availability of borated water occurs early in the steam line break transient when RCS pressures are relatively high and SI flowrates are relatively small due to head vs SI flow characteristics.

1

I Att chment I to ET'87-0180 Pags 2 of 3 May 7, 1987

2) Previous sensitivities 'have shown that' delays cf this magnitude result in small changes in the analysis results. A comparison of cases with and without the additional Safety Injection Signal (SIS) delay showed, over the limiting portion of the transient, maximum differences of 0.25 in_ power, 0.6 deg-F in RCS temperature, and 10 psia in RCS pressure. A WCGS specific review of the steam line break analys's demonstrated that there is sufficient margin available in the analysis such that the conclusions presented in the USAR remain valid.

3) The analysis assumes only one high-head charging pump is available. However, at the pressures characteristic of a steam line break, all of the SI pumps of a given train would be available to deliver a significantly greater flowrate of borated water to the RCS.

From analyses performed for other plants, it has been shown that SI boron concentration reduction has little effect on the steam line break mass / energy release analysis inside containment. Since the additional time delay is a small perturbation compared to a large change in the available boron concentration, there will be a negligable impact on the steam line break mass / energy release inside containment analysis.

Sensitivities performed for the steam line break superheated mass / energy release outside containment analysis show that the results are not sensitive to large changes in SI flow (Reference WCAP-10961, Rev. 1). The additional time delay is a small perturbation compared to a large change in total SI flow; therefore, it is concluded that the impact on the Wolf Creek superheated mass / energy releases outside containment is insignificant.

In the case of a Loss of Coolant Accident, the immediate safety function of SI is to supply water to the RCS, whether borated or not. The time at which water (from either the VCT or the RWST) is available to the suction of the high-head charging pumps is not affected. Thus, _for those SI actuation signals that are only intended protection against a LOCA, this additional delay is not required since boron is only required for maintaining suberiticality in the long term following a LOCA.

i Conclusion The proposed change in the ESF response times for Containment Pressure -

High-1, Pressurizer Pressure-Low and Steam Line Pressure-Low in Technical Specification Table 3.3-5 Items 2a, 3a and 4a to incorporate an increase of 15 seconds is acceptable. Evaluation of the impact on the WCGS safety analysis licensing basis demonstrates that the conclusions in the USAR remain valid.

I Att chment I to ET 87-0180 Page 3 of 3 May 7,1987 Dased on the above discussions and the considerations presented in Attachment II, the proposed revisions to Technical specification Table 3.3-5 and its associated Bases do not increase the probability of occurence or the consequences of an accident or malfunction of equipment important to safety previously evaluated in the safety analysis report; or create a possibility for an accident or malfunction of a different type than any evaluated previously in the safety analysis report; or reduce the margin of safety as defined in the basis for any technical specification. Therefore, the proposed revisions do not adversely affect or endanger the health or safety of the general public or involve a significant safety hazard.

ATTACHMENT II SIGNIFICANT HAZARDS CONSIDERATION

Attachment II to ET 87-0180 Page 1 of 1 May 7,1987 SIGNIFICANT HAZARDS CONSIDERATION This license amendment request proposes revising Technical Specification Table 3.3-5 and its associated Bases to change the Engineered Sa fety Features (ESF) response times for items 2.a. (Containment Pressure-High-1, Safety Injection), 3.a. (Pressurizer Pressure-Low, Safety Injection), and 4.a. (Steam Line Pressure-Low, Safety Injection). These changes are being made to more accurately reflect the time required to transfer charging pump suction from the Volume Control Tank to the Refueling Water Storage Tank.

1. The proposed changes do not involve a significant increase in the probability or consequences of an accident previously evaluated.

Increasing the acceptance criterion for the ESF response times is acceptable since evaluation of the impact of the increased response times on the steam line break event demonstrated that the DNB design basis is still met. The conclusions in the Updated Safety Analysis Report (USAR) remain valid. These changes do net involve i a change in the operational limits or physical design of the involved systems.

2. The proposed changes do not create the possibility of a new or different kind of accident from any accident previously evaluated.

There are no new failure modes associated with the proposed change, as no design changes have been made. These changes do not involve a change in the operational limits or physical design of the involved systems. Existing plant equipment will be utilized as before the proposed change. Therefore, an increase in the ESF response times for Containment Pressure-High-1, Pressurizer Pressure-Low, and Steam Line Pressure-Low does not create the possibility of an accident or malfunction of a different type than any evaluated previously in the safety analysis report.

3 The proposed changes do not involve a significant reduction in a margin of safety. The proposed changes are intended to bring the technical specification surveillance requirements into agreement with the Bases for the technical specification. Since there is no impact on the conclusions presented in the USAR all existing safety limits are still valid.

Based on the above discussions and those presented in Attachment I, it has been determined that the requested Technical Specification revisions do not involve a significant increase in the probability or consequences of an accident or other adverse condition over previous evaluations; or create the possibility of a new or different kind of accident or condition over previous evaluations; or involve a significant reduction in a margin of safety. Therefore, the requested license amendment does not involve a significant hazards consideration.

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