ML20081F563

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Application for Amends to Licenses NPF-11 & NPF-18,providing Enhancements to Tech Specs Which Reflect Improvements Made to ATWS-RPT Instrumentation & Logic Sys
ML20081F563
Person / Time
Site: LaSalle  Constellation icon.png
Issue date: 06/04/1991
From: Piet P
COMMONWEALTH EDISON CO.
To:
NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20081F567 List:
References
NUDOCS 9106100507
Download: ML20081F563 (9)
v • d • e


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EN Ccmmenwealth Edison 10 CFR 50.90

  • C ) 1400 Opus Place O Downers Grove. tilinois 60515 June 4, 1991 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Hashington, D.C. 20555

Subject:

LaSalle Couniy Station Units 1 and 2 Application for Amendment to Facility Operating Licenses NPF-ll and NPF-18, Appendix A, Technical Specification Improvements for the Anticipated Transient Without Scram - Reactor Recirculation Pump Trip (ATHS-RPT)

NRC_DocheLNos ,_50-313_and 50-314__

References:

(See Attached Sheet)

Gentlemen:

Pursuant to 10 CFR 50.90, Commonwealth Edison (CEro) proposes to amend Apoendix A Tcchnical Specifications, of Facility Operating Licenses NPF-11 and NPF-18. The proposed amendment provides e bancements to the I Technical Specifttations which reflect the improvement rade to the ATHS-RPT instrumentction and logic system. The proposed Technical Specifications are modelled after Limerick Unit 2. The ATHS-RPT instrumentation for LaSalle Station is scheduled to be modified to be functionally equivalent te the instrumentation at Limerick. It is requested that the amendments be made

effective upon issuance for Unit I and no earlier than the beginning of Refuel Outage L2R04 for unit 2.

l This proposed rmendment request is subdivided as follows:

1. Attachment A gives a description and safety analysis of the proposed changes in this amendment.

! 2. Attachment B includes the marked-up Technical Specifications pages with the requasted changes indicated.

3. Attachment C describes CECO's evaluation performed in accordance with 10 CFR 50.92 (c), which confirms that no significant hazards consideration is involved.
4. . Attachment D provides the Environmental Assessi.;ent.

This proposed amendment has been reviewed and approved by CECO On-Site and Off-Site Review in accordance with Commonwealth Edison procedures.

9106100507 910604 DR ADOCK 0500 3 gpff tji

U.S. Nuclear Regulatory Commission June 4, 1991 To the best of my knowledge and belief, the information contained within is true and correct. In some respect these statements are not based on my personal knowledge, but obtained information furnished by other Commonwealth Edison employees, contractor employees, and consultants. Such information has been reviewed in accordance with company practice, and I believe it to be reliable.

Commonwealth Edison is notifying the State of Illinois of this application for amendment by transmitting a copy of this letter and its attachments to the designated state official.

Please direct any questions you may have concerning this submittal to this office.

Very truly yours,

-+ M Peter L. Piet Nuclear Licensing Administrator Attachments: A. Description of Safety Analysis or the Proposed Changes B. Marked-up Technical Specification Pages C. Evaluation of Significant Hazards Considerations D. Environmental Assessment l cc: A.B. Davis - Regional Administratoi, RIII l Senior Resident Inspector - LSCS l B.L. Siegel - NRR, Project Manager Office of Nuclear facility Safety - IDNS PLP:cag ZNLD841/13-15

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Signed before me on this ZM_ day

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-U.S. Naclear Regulatory Commission June 4, 1991 REIERENCES (a) NRC Generic letter 85-06, " Quality . Assurance Guidance for ATHS Equipment i that is not Safety-Related."

(b) 10 CFR 50.62, " Requirements-for Reduction of Risk from Anticipated Transients Without Scram (ATHS) Events for Light Hater-Cooled Nuclear Power Plants."

(c) Regulatory Guide 1.105, " Instrument Setpoints for Safety-Related Systems."

(d) NUREG-1371, July 1939, " Technical Specifications Limerick Generating Station, Unit Na, 2".

(e) LAP-1600-11. " Control of Technical Specification Work Activities,"

Revision 4, January 6, 1988.

(f) H.R. Butler letter to D.L. F:rrar dated September 20, 1985, Issuance of Amendment 24 to NPF-11

A11ACHMENL A 4

' DESCRIPTION AND SAFETY ANALYSIS Of PROPOSED CHANGES 10 APPENDIX A, 1ECHNICAL SPLCiflCATIONS Of FACILITY OPLRATINC LICINSIS NPf-Il AND NPf-18 BACKGROUND An ATHS is an expected operational transient, such as, loss of feedwater, loss of condenser vacuum, loss of off-site power, main steam isolation valve closure, turbine trip, or inadvertent opening of a safety relief valve, accompanied by a failure of the Reactor Protection System (RPS) to shutdown the reactor. The ATHS-RPT system provid(s a means of limiting the consequences of the un!)Lely occurrence of such an event. This is accomplished by reducing reactor power levels by tripping the reactor recirculation (RR) pumps when an ATHS conditian is sensed. The ATHS-RPT logic system relies on high reactor pressure and/or low reactor water level to provide indication of the existence of an ATHS condition. The system senses reactor level and pressure and will cause a trip cf the RR pumps should these parameters reach certain values well outside of the normal RPS trip levels.

The NRC has expressed several concerns relating to the adequacy of the currently installed ATHS-RPT logic system (References (a), (b), and (c)).

These concerns primarily relate to the completeness of testing, testability at power, and reliability (avoidance of spurious trips) of the system. The station is in the process of implementing station modifications to address these concerns. The Unit 1 modification has been completed and the Unit 2 modification is scheduled for completion in early 1992. The original instrumentation is configured into two trip systems each with a "l-out-of-four taken once" logic scheme. One trip system is used for each reactor recirculation (RR) pump. The modifications will:

1. upgrade the trip system instrumentation to a new analog system, and
2. alter the ATHS-RPT logic to create two separate trip systems of "l-out-of-2 taken twice" logic with each trip system capable of tripping both RR pumps under ATHS conditions, LaSalle Station performed an evaluation to determine if any Technical Specification amendments a e required to be completed prior to implementation of the plant modifications. The review concluded that the current requirements provide adequate controls for the new trip system and that no amtndments are required to be in place prior to the implementation of the modification. However, it was also dete' mined that the following changes would be desirable to further clerify the Technical Specification requirements and to make the LaSalle Station 'iechnical Specifications more consistent with other similar BWRs:
  • Table 3.3.4.1 revise the minimum number of operable channels per trip system for the reactor water level and pressure instrumentation from one to two channels, and
  • Table 4.3.4.1 revise the channe' check requirement for the reactor vessel high pressure instruments from "Not Apolicable" to "Shiftly."

Hii)e41/16

AUACHMENLAJContinuedi DISCUSS 10lf Technical Specification Table 3.3.4.1-1 requires that a minimum of one channel in each ATHS-RPT trip function per trip system be operable.

Currently under this requirement, only one of the two low water level trips and one of the two high pressure trips, in each instrumentation trip system, is required to-be operable. With a "1-out-of-4 taken once" logic scheme, only one of the trips is needed-in a trip system to cause the trip of one RR pump (refer to figure 1). Both trip systems must actuate to trip both pumps.

Therefore, with the currently existing instrumentation and Technical Specification requirements, a channel is considered to be one reactor water level or pressure sensor and its associated trip relay, following modification of the trip system, a modified "1-out-of-2 taken twice" logic scheme will be established. The new system will need a combination of at least two of the four reactor low water level or high pressure trips to actuate in either trip system to complete the required trip function (refer to figure 1). If an ATHS-RPT channel is considered to be one level or pressure sensor, as it currently is, a Technical Specification which requires only cne channel per trip system to be operable would be inadequate.

With-only one sensor operable, the trip system would be inoperable even though all Technical Specification requirements would be met. However, if the ATHS-RPT " channels" are defined to be the logic required to cause a trip of both RR pumps, then the existing Technical Specification renuirements adequately enforce the availability of the RPT function.

Station procedure LAP-1600-11 (Reference (e)) defines an instrument channel as follows:

"An arrangement of components and modules designed to generate a

-single protective-action signal (High Drywell Pressure, Vessel Low Level', Etc.)."

This definition adequately justifies the use of the revised logic with the existing-Technical Specification. Reference (e) also contains'several figures that provide examples of different instrument channel configurations. As an interim measure, this procedure will be revised to include specific examples of tne ATHS-RPT instrumentation and how a channel is defined for Unit 1 following the modification and for Unit 2 as it will exist until the modifications are completed. For the long term, LaSalle Station proposes to amend the Technical Specification action _ requirements and Table a.3.4.1-1 to fully: utilize the improvements-made to the ATHS-RPT instrumentation.

A review of the Technical Specifications for several recently licensed BHRs was performed. It was determined that the Limerick Generating Station Unit No. 2 currently has-limiting conditions for operation (LCO) and action requirements in place for their ATHS-RPT instrumentation that appeared to be intended for use with a logic system similar to that being installed at LaSalle Station-(Reference (d)). Limerick Station was contacted and they-provided a one line diagram of their ATHS-RPT logic system. The Limerick diagram confirmed- that each of their trip systems uses a "1-out-of-2 taken twice" logic scheme and that each of tha trip systems is designed to trip both reactor rect culation pumps. Therefore, the ATHS-RPT instrumentation for LaSalle Station-when modified will be essentially th9 same as that at Limerick.

NLD84 U17

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ALTACHMENLUContinued)

The ATHS-RPT LCO and Action Requirement a. are the same in both the LaSalle and Limerick Technical Specifications. Actions b. through e. in the Limerick Technical Specifications cover all possible combinations of inoperable channels and trip systems with appropriate allowed outage times for each case. Action b. in the LaSalle Technical Specifications only addresses the situation where one channel in one trip system is inoperable and provides a 14 day allowed outage time for this situation. Any other situation would necessitate an immediate shutdown under the provisions of Technical Specification 3.0.3.

It is proposed that Technical Specification 3.3,4.1 Action b. In the LaSalle Station Technical Specifications be replaced with Actions b. through

e. from the Limerick Unit 2 specifications. The Limerick specification provides a higher degree of protection and operational flexibility by addressing all possible combinations of inoperable channels and trip systems with appropriate action requirements and allowed outage times. The requirements are clear and easily understood thus redut',m the potential for misinterpretation of the Technical Specifications by '" on operators.

The ATHS-RPT instruments currently installed tecting reactor high pr essure do not proutda direct pressure indication. 's a result, a channel check for these instruments is not possible, and she Technical apecifications do not include a requirement for a periodic channel check. The new ATHS-RPT high reactor pressure instrumentation being installed as a plant modification does provide direct pressure indication. Therefore, a requirement for a shiftly channel check is being proposed as an amendment to Table 4.3.4.1-1 (refer to Attachment B). The station operating procedures will be revised to require a shiftly channel check of the ATHS-RPT as soon as the instrumentation is installed on each unit. Approval of this amendment is not required prior to implementation of the modification.

In addition to the amendments noted above, footnote "*" at the bottom of page 3/4 3-35 of the Unit 1 Technical Specifications will be removed as indicated in Attachment B. This footnote provided a waiver for certain surveillance requirements during the first cycle for Unit 1 (Reference (f)).

This footnote no longer applies and should be deleted.

SUMM&R1 The following amendments to the LaSalle County Unit 1 and Unit 2 Technical Specifications (refer to Attachment B) are being submitted for approval:

1. Amend the action requirements for Technical Specification 3.3.4.1 to take full advantage of the improvements made to the ATHS-RPT gic and to be consistent with other recently licensed BHRs.
2. Amend the minimum number of operable channels in Table 3.3.4.1-1 for the low water level and high pressure instrumentation from one to two.

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3. Amend the channel check requirement for the reactor pressure-high instrumentation from "not applicable ' to "Shif tly.
4. Remove footnote "*" at the bottom of Page 3/4 3-35 (Unit 1 only).

Approval of these amendments is not required prior to 'molementation of the modifications to either Units I or 2. The amendments should be made effective upon issuance for Unit 1 and no earlier than the beginning of Refuel Outage c2R04 for Unit 2.

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ATTACHMENT A (continued)

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AllACHMENLA100ntinuedl

-REEERENCES (a) NRC Generic Letter 85-06, " Quality Assurance Guidance for ATHS Equipment-that-is not Safety-Related."

(b) 10 CFR 50.62, " Requirements for Reduction of Risk from Anticipated Transients Hithout Scram (ATHS) Events for Light Water-Cooled Nuclear Power Plants."

(c) Regulatory Guide 1.105, " Instrument Setpoints for Safety-Related Systems."

(d) NUREG-1371, July 1989, " Technical Specifications Limerick Generating

. Station, Unit No. 2".

(e) LAP-1600-II, " Control of Technical Specification Hort Activities,"

Revision 4, January 6, 1988.

-(f) H.R. Butler letter to D.L. Farrar dated September 20, 1985, Issuance of Amendment 24 to NPF-11.

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IfLD941/21

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