ML17285A358

Application for Amend to License NPF-21,revising Tech Specs 3/4.2.6 Re Power Flow Instability & 3/4.2.7 Re Neutron Flux Noise Monitoring in Support of Supply Sys Response to NRC Bulletin 88-007,Suppl 1

ML17285A358
Person / Time
Site:	Columbia
Issue date:	03/31/1989
From:	Sorensen G WASHINGTON PUBLIC POWER SUPPLY SYSTEM
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML17285A359	List: ML17285A358 ML17285A360
References
GO2-89-051, GO2-89-51, IEB-88-007, IEB-88-7, TAC-72924, NUDOCS 8904100262
Download: ML17285A358 (12)

Text

ACCELEP>TED DISIBUTION DEMONSTRON SYSTEM REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)

ACCESSION NBR:8904100262 DOC.DATE: 89/03/31 NOTARIZED: YES DOCKET FACIL:50-397 WPPSS Nuclear Project, Unit 2, Washington Public Powe 05000397 AUTH. NAME AUTHOR AFFILIATXON SORENSEN,G.C. Washington Public Power Supply System RECXP.NAME 'ECIPIENT AFFILIATION Document Control Branch (Document Control Desk)

R Application for amend to License NPF-21,revising j

SUBJECT:

Tech Spec 3/4.2.6 & 3/4.2.7. I DISTRIBUTION CODE: AOOID COPIES RECEIVED:LTR ~ENCL SIZE:'l (0 + ~~~

TITLE: OR Submittal: General Distribution NOTES:

RECXPIENT COPIES RECIPXENT COPIES ID CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL PD5 LA 1 1 PD5 PD 1 1 SAMWORTH,R 5 5 INTERNAL: ACRS 6 6 NRR/DEST/ADS 7E 1 1 NRR/DEST/CEB 8H 1 ' NRR/DEST/ES B 8D 1 1 NRR/DEST/ICSB 1 1 NRR/DEST/MTB 9H 1 ~ 1 NRR/DEST/RSB 8E 1 1 NRR/DOEA/TSB 11 1 1 NUDOCS-ABSTRACT 1 1 OC 1 0 OGC/HDS2 1 0 G FILE 01 1 1 RES/DSIR/EXB 1 1 EXTERNAL: LPDR 1 1 NRC PDR NSIC 1 1 R

I NOTE 'IO ALL "RIDS" RECIPIEMIS:

PLEASE HELP US 'lO REDUCE WASTE! Col'ACT 'IHE IXCUNEÃZ (XÃIBDL DESK, BOOM Pl-37 (EXT. 20079) IO ELI?GXLTE YOUR NAME FRY DISTRIBUTION LISTS FOR DOCtBKÃIS YOU DON'T NEED!

TOTAL NUMBER OF COPIES REQUIRED: LTTR 28 ENCL 26

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WASHINGTON PUBLIC POWER SUPPLY SYSTEM P.O. Box 968 ~ 3000 George Washington Way ~ Richland, Washington 99352 March 31, 1989 G02-89-051 Docket No. 50-397 U. S. Nuclear, Regulatory Commission Attn: Document Control Desk Nail Station Pl-137 Washington, D.C. 20555 Gentlemen:

Subject:

NUCLEAR PLANT NO. 2 OPERATING LICENSE NPF-21, REQUEST FOR AMENDMENT TO TECHNICAL SPECIFICATIONS 3/4.2.6, POWER FLOW INSTABILITY AND 3/4.2.7 NEUTRON FLUX NOISE MONITORING IN SUPPORT OF THE SUPPLY SYSTEM RESPONSE TO IEB 88-07, SUPPLEMENT 1

Reference:

IE Bulletin 88-07, Supplement 1, "Power,, Oscillations in Boiling Hater, Reactors (BWRs)", dated 12/30/88

2) Letter, G02-89-030, GC Sor ensen (SS) to NRC, "Response to IE Bulletin 88-07, Supplement 1", dated 3/3/89

3) Letter G02-89-029, GC Sorensen (SS) to NRC, "Request for, Amendment to Technical Specifications Reload License Amendment (Cycle 5)", dated 3/3/89 The response to IEB 88-07, Supplement 1 (reference 1) provided in reference 2 stated in part that the Supply System would submit a proposed technical speci-fication amendment to replace the existing detect-and-suppress technical speci-fications with specifications based on the Advanced Nuclear Fuels (ANF) ANNA Stability Monitoring System. The current specifications require evaluation of neutron signal noise against a baseline noise level. The ANNA system provides a much str onger, faster, more sophisticated means of monitoring the stability of the reactor. core.

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'Page Two RE()UEST FOR AMEND. TO TS 3/4.2.6 POWER FLOW INSTABILITY AND 3/4.2.7 NEUTRON FLUX NOISE MONITORING IN SUPPORT OF THE SUPPLY SYSTEM RESPONSE TO IEB 88-07, SUPPLEMENT 1 As described in reference 2, the Supply System has implemented the General Electric Interim Operating Recommendations as requested in reference 1. This implementation includes the definition of Regions A, B and C as defined in the recommendations. The Supply System proposes a reduction in Region B (a region where operation is prohibited) and a corresponding increase in Region C (a region where operation is allowed under. controlled conditions). The basis for, this proposal is that the use of the stronger monitoring capabilities represented in the ANNA system compensates for, an enlarged allowable operating region, such that the present safety margin is maintained. This approach was discussed with L. Phillips and H. Ritchings of your, staff on January 31, 1989.

Hence, in accordance with the Code of Federal Regulations, Title 10, 'Parts 50.90 and 2.101, the Supply System hereby submits a request for, amendment to the WNP-2 Technical Specifications. Specifically, the Supply System is requesting that the subject Technical Specifications be modified, as attached, to reflect the enhanced operating capabilities of the ANNA system over the present detect-and-suppress stability monitoring capabilities.

The proposed Technical Specification changes are intended to be implemented within the framework of the Interim Operating Recommendations. The recommenda-tions will be modified to the extent that Region C is enlarged, and the ANNA system will support SIL 380 methods for detecting the onset of core insta-bility. The basis for enlargement of Region C is as follows: Those portions of Region B which fall outside a region of 0.9 decay ratio as calculated by Advanced Nuclear. Fuels (ANF) (in support of reload license applications) will be redefined as part of Region C, where oper ation is allowed under. a controlled manner, when fuel preconditioning is required. Those areas below the 100K rodline for which the calculated decay ratio is greater, than 0.9 will remain defined as Region B, where planned operation is prohibited. For, cycle 5 opera-tion, decay ratio calculations indicate no value .of 0.9 or greater exists for points beneath the 1005 rodline. Therefore this application, which is being made in support of, and subsequent to, the cycle 5 reload license application, provides for, complete replacement of Region B with Region C (as they are currently defined in tHe Interim Operating Recommendations). For, future cycles in which decay ratio values of 0.9 or greater, are calculated for points below the 1005 rodline, the allowable region will be modified accordingly.

e t Page Three REQUEST FOR AMEND- TO TS 3/4.2.6 POWER FLOW INSTABILITY AND 3/4.2.7 NEUTRON FLUX NOISE MONITORING IN SUPPORT OF THE SUPPLY SYSTEM RESPONSE TO IEB 88"07, SUPPLEMENT 1 Although the proposed changes are to be implemented within the framework of the Interim Operating Recommendations, the Supply System has structured the pro-posed Technical Specifications to be applicable to a viable long-term solution with a minimum number. of addi-tional changes. This solution incorporates a stability monitor, for, maneuvering in conjunction with additional automatic protection for power, operation, and is one of the final solutions currently under, consideration by the BWROG Stability Committee.

The current Technical Specifications incorporate the recommendations of General Electric Service Information Letter, (SIL) No. 380 Revision 1 and the Staff's Safety Evaluation Report of GE Topical Report NEDE-24011 amendment 8. The current specifications define a "detect-and-suppress" region. Prior, to entry into this region, a baseline set of neutron signal noise values must be esta-blished. When operating in the region, neutron signal values must periodically be compared to these baseline values. If noise levels exceed baseline levels by a specified amount, action must be taken to exit the region. The basis for, this "detect-and-suppress" . approach is that neutron signal noise has been demonstrated to increase as the core decay ratio increases. The limits for acceptable noise are selected such that action will be taken before the onset of an instability results in limit cycle operation.

A stability monitoring system such as the ANNA system represents a significant improvement in monitoring the stability of a reactor, core. The ANNA system performs a sophisticated noise analysis technique to calculate the decay ratio of each of multiple neutron signals (LPRM and APRM). These calculations are performed automatically, such that peak-to-peak and decay ratio data is presented in near. real-time. As a result, the ANNA system provides information more rapidly than existing methods, and without the distractions to control room staff imposed by current methods. In addition, the decay ratio informa-tion available through the ANNA system is a primary indicator, of the state of the cor.e stability, whereas the current indicator,, neutron signal noise level, is an indirect, less reliable means. Through use of the ANNA system a much more quantitative measure of the margin to instability exists, i.e. how close the measured decay ratio is to 1.0. This significant improvement in detecting the approach to a region of instability is the justification for the proposed enlargement of Region- C. The Supply System has reviewed this amendment request per, 10 CFR 50.92 and has determined that it does not represent an unreviewed safety question or, a significant hazar d because it does not:

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Page Four, REQUEST FOR AMEND. TO TS 3/4.2.6 POWER FLOW INSTABILITY AND 3/4.2.7 NEUTRON FLUX NOISE MONITORING IN SUPPORT OF THE SUPPLY SYSTEM RESPONSE TO IEB 88-07, SUPPLEMENT 1 Involve a significant increase in the probability or consequences of an accident previously evaluated because, as discussed above, the ANNA system represents a substantial improvement in the capability to detect-and-suppress, such that the present safety margin is preserved for, operation in an expanded Region C. The enlarged Region C represents a region in which operation was allowed for, WNP-2 until recently when the Interim Operating Recommendations were implemented. As discussed above, operation in this region was allowed provided detect-and-suppress noise monitoring requirements were satisfied. No instability events have been detected during oper ation at WNP-2. Recently, a portion of this region became prohibited from planned operation through adoption of the Interim Operat-ing Recommendations. These Interim Operation Recommendations were made in response to GE calculations which showed, particularly for the later classes of GE plants, less margin to the MCPR safety limit may exist than was previously evaluated for, a certain class of limit cycle instability events. These recommendations were made in order to provide assurance that plants would not enter a region of unstable operation and experience limit cycle events which could violate the safety limit. The use of the ANNA system provides greatly improved ability to detect the approach to a region of instability. It is the Supply System's judgement that this improved detection capability more than compensates for the enlargement of Region C such that the present safety margin is preserved and in fact increased. Hence, the probability or consequences of previously evaluated accidents are not increased by this change.

2) Create the possibility of a new or, different kind of accident from any accident previously evaluated because the design basis function, to detect-and-suppress core instability events, remains the same and is enhanced by the ANNA system. The enlargement of the allowable operating region does not introduce any new or. different kind of accident, either stability or. non-stability related. Enlargement of the region does necessitate justification that the probability of occurrence of an insta-bility event is not increased. This issue has been addressed above. The ANNA system is very similar, to the current method in terms of the equip-ment employed to monitor, the core. Both systems involve use of computer software. The ANNA system therefore does not introduce any new failure modes over. existing detect-and-suppress methods. In fact, the specific manner, in which WNP-2 is implementing ANNA will reduce the risk of postu-lated computer, failures, in that completion of an operability surveillance is required prior, to entry into the region. In addition, the ANNA system automatically provides a warning in the event of a failure. Hence a new or, different kind of accident due to implementation of ANNA and enlarge-ment of Region C is not credible.

Page Five RE()UEST FOR AMEND TO TS 3/4.2.6 POWER FLOW INSTABILITY AND 3/4.2.7 NEUTRON FLUX. NOISE MONITORING IN SUPPORT OF THE SUPPLY SYSTEM RESPONSE TO IEB 88"07, SUPPLEMENT 1

3) Involve a significant reduction in a margin of safety because as discussed above, the implementation of ANNA provides improved detection capability which more than compensates for, the enlargement of Region C. Hence, there is no reduction in the margin of safety due to this proposal.

As discussed above, the Supply System consider:s that this change does not involve a significant hazards consideration, nor. is there a potential for significant change in the types or significant increase in the amount of any effluents that may be released offsite, nor, does it involve a significant increase in individual or. cummulative occupational radiation exposure. Accor-dingly, the proposed change meets the eligibility criter ia for categorical exclusion set forth in 10CFR 51.22(c)(9) and therefore, per 10CFR 51.22(b), an environmental assessment of the change is not required.

This Technical Specification change has been reviewed and approved by the WNP-2 Plant Operations Committee (POC) and the Supply System Corporate Nuclear, Safety Review Board (CNSRB). In accordance with 10CFR 50.91, the State of Washington has been provided a copy of this letter.

Very truly yours, G. C. Sorensen, Manager Regulatory Programs PLP/bk Attachments cc: C Eschels - EFSEC JB Martin - NRC RV NS Reynolds - BCP8R RB Samworth NRC DL Williams - BPA/399 NRC Site Inspector. - 901A

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COUNTY OF BENTON ) Z/Sf. E.7 I, G. C. SORENSEN, being duly sworn, subscribe to and say that I am the Manager, Regulatory Programs, for, the WASHINGTON PUBLIC POWER SUPPLY SYSTEM, the applicant herein; that I have full authority to execute this oath; that I have reviewed the foregoing; and that to the best of my knowledge, information and belief the statements made in it are true.

DATE 9/ N CW, 1989 G. C. SOfPNSEN, Manager Regulatory Programs On this day personally appeared before me G. C. SORENSEN to me known to be the individual who executed the foregoing instrument and acknowledged that he signed the same as his free act and deed for the uses and purposes herein mentioned.

GIVEN under my hand and seal this ~s day of ,1989.

Notar u s a d r e State of Washington Residing at Ws"sask My commission ex ires 7/14/91.

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