ML17298A814

Forwards Addl Info Re Impact of High Energy Line Breaks on Control Sys,Per 831205 & 13 Telcon Concerns Re Question 222.03

ML17298A814
Person / Time
Site:	Palo Verde
Issue date:	02/14/1984
From:	Van Brunt E ARIZONA PUBLIC SERVICE CO. (FORMERLY ARIZONA NUCLEAR
To:	Knighton G Office of Nuclear Reactor Regulation
References
ANPP-28870-WFQ, NUDOCS 8402160069
Download: ML17298A814 (12)

Text

REGUI ATUR NFORMATION DISTRIBUTION S I'EM (RIDS)

C ACCESSION NBR:8402160069 DOC.DATE: 84/02/14 NOTARIZED: YFS DOCKET FACIL:STN-50 5?8 'Palo Verde Nuclear Station~ Unit 1E Arizona Publi 05000528 STN-50-529 Palo Verde Nuclear StationE Unit 2E Arizona Publi 05000529 STN-50-530 Palo Verde Nuclear Stationi Unit 3i Arizona Publi BYNAME 05000530 AUTH AUTHOR AFFILIATION VAN BRUNTEE ~ ED Arizona Public Service Co ~

RECIP ~ NAME RECIPIENT AFFILIATION KNIGHTON p G ~ N ~ Licensing Branch 3

SUBJECT:

Forwards addi info re impact of high energy line breaks on control -sysEper 831205 8 13 telcon concerns re Question 222,03 CODE: 8001S

'ISTRISUTION COPIES RECEIVED:LTR J. ENCL J SIZE:

TITLE: Licensing Submittal: PSAR/FSAR Amdts 8, Related Correspondence NOTES:Standardized plant. 05000528 Standardized plant. 05000529 Standardized plant ~ 05000530 RECIPIENT COPIES REC IP.IENT COPIES IO CODE/NAME LTTR ENCL IO CODE/NAME LTTR ENCL NRR/DL/ADL 1 0 NRR LB3 BC 1 0 NRR LB3 LA= 1 0 LICITRAg E, 01 1 1 INTERNAL: ELD/HDS3 1 0 IE FILE 1 1 IE/DEPER/EPB 36 3 3 IE/OEPER/IRB 35 1 IE/OQASIP/QAB21 1 1 NRR/DE/AEAB 1 0 NRR/DE/CEB 11 1 1 NRR/DE/EHEB 1 1 NRR/DE/EQB 13 2 2 NRR/DE/GB 28 2 2 NRR/DE/MEB 18 1 1 NRR/OE/MTEB 17 1 NRR/DE/SAB 24 1 1 NRR/DE/SGEB 25 1 1 NRR/DHFS/HFEB40 1 1 NRR/DHFS/LQB 32 1 1 NRR/DHFS/PSRB 1 NRR/DL/SSPB 1 0 NRR/DS I/AEB 26 1 1 NRR/DSI/ASB 1 1 NRR/DSI/CPB 10 1 1 NRR/DSI'/CSB 09 1 NRR/DSI/ICSB 16 1 1 NR R/D S I /ME T B,l 2 1 1 NRR/DSI/PSB 19 1 N RAB 22 1 1

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Arizona Public Service Company P.O. BOX 21666 ~ PHOENIX, ARIZONA 85038 February 14, 1984 ANPP-28870 WFQ/MSN Director of Nuclear Reactor Regulation Attention: Mr. George Knighton, Chief Licensing Branch No. 3 Division of Licensing U.S. Nuclear Regulatory Commission Washington, D.C. 20555

Subject:

Palo Verde Nuclear Generating Station (PVNGS)

Units 1, 2 and 3 Docket Nos. STN-50-528/529/530 File: 84-056-026; G.l. 01.10

Reference:

APS Letter, ANPP-28239-WFQ/MSN, from E. E. Van Brunt, Jr.

to G. W. Knighton, dated November 16, 1983

Subject:

Additional Information Regarding the Impact of High Energy Line Breaks on Control Systems

Dear Mr.'nighton:

The referenced letter provided additional information regarding Question 222.03 (see FSAR Round 1 Questions). Telecons were held on December 5 and 13, 1983 between NRC, APS, Bechtel and Combustion Engineering personnel to discuss further NRC concerns regarding Question 222.03.

Attached are the NRC questions discussed duxing the December 5 and 13, 1983 telecons and our pxepared response to them. We believe this xesponse adequately responds to all NRC concerns and provides sufficient information to complete the safety evaluation on this subject.

Very truly youxs, E. E. Van Brunt, Jr.

APS Vice President, Nuclear ANPP Project Director EEVB/MSN:sls Attachment cc: E. A. Licitra (w/a)

A. C. Gehr (w/a) 8402l60069'40214 PDR ADOCK 05000528 A , PDR

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STATE OF ARIZONA )

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COUNTY OF MARICOPA)

I, Edwin E. Van Brunt, Jr., represent that I am Vice President, Nuclear, of Arizona Public Service Company, that the foregoing document has been signed by me on behalf of Arizona Public Service Company with full authority to do so, that I have read such document and know its contents, and that to the best of my knowledge and belief, the statements made therein are true.

F F.

Edwin E. Van Brunt, Jr.

Swore to before me thief+ 4t, day of o~o, 1984.

otary Public My Commission Expires:

My Commlsston Expires April 6, 1987

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ATTACHMENT Response to Additional NRC Concerns Regarding Question 222.03 on PVNGS High Energy Break Analysis/Control System Malfunctions NRC Concern 1.(A) What would be the event consequences of simultaneous failure of the Pressurizer Pressure Control System (PPCS) and Reactor Regulating System (RRS) with and without Steam Bypass Control System (SBCS) failure due to a Steam Line Break (SLB)7 (B) In the referenced letter regarding: "...PPCS failure in conjunction with any other control system failures will not exacerbate event consequences. What are the failure combinations and how are they bounded2 Res onse

1. (A) The event consequences due to the simultaneous failure of any or all of the combinations of the PPCS, SBCS and RRS in conjunction with a SLB event are bounded by the SLB consequences presented in section 15.1.5 of the PVNGS FSAR.

The event consequences due to the simultaneous failure of the PPCS and RRS in combination with a Less of Coolant Accident (LOCA) are bounded by the LOCA consequences presented in section 15.6.5 of the PVNGS FSAR.

The event consequences due to the simultaneous failure of the RRS and Pressurizer Level Control System (PLCS) in combination with a Feedwater Line Break (FWLB) event are bounded by the FWLB consequences presented in section 15.2.8 of the PVNGS FSAR.

The failure combinations of concern are: failure of the PPCS, SBCS and RRS during a SLB and failure of the PPCS and RRS during a LOCA. The failure combinations are bounded by the events given in the response to item 1.(A).

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ATTACHMENT (Page Two)

NRC Concern

2. In the referenced letter regarding: "...the combined failure of the SBCS and RRS during an SLB event is not credible since there are interlocks within these control systems which prevent simultaneous operation of the two control systems".

2.(A) Is it possible that the High Energy Line Break (HELB) will also fail the interlocks Is this a common mode failure2 2,(C) Provide additional information which illustrates that the HELB will not fail the control system interlocks.

Res onse 2.(A) No.

2.(B) No.

2. (C) The event scenario of concern is the failure of the SBCS such that a Quick Open Signal (refer to CESSAR-F Section 7.7.1.1.5) is generated in combination with a RRS malfunction during a SLB inside the Containment Building.

The capability of the SBCS to produce an Automatic Withdrawal Prohibit (AWP) given the generation of Quick Open signals or of the Control Element Drive Mechanism Control System (CEDMCS) to act on the AWP will not be impaired due to this HELB. The SBCS is located in cabinets behind the main control room panels but in the control room environment (Figure 7.5-1 of the PVNGS FSAR). The CEDMCS is located on the 120 foot level of the Auxiliary Building (See attached drawing No. 13-J-ZAF-020, Revision 7, dated January 31, 1984, for CEDMCS cabinets J-SFN-C01A through C01D). Therefore these control systems (SBCS and CEDMCS) are not exposed to the HELB environment in the Containment Building due to a SLB.

The SBCS generates an AWP signal whenever a SBCS demand

,, for opening the Turbine Bypass Valves exists, whether the SBCS demand is generated due to normal or faulted input signals. This signal is sent to the CEDMCS to block its response to RRS demands, for withdrawing Control Element it

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Assemblies (CEAs). This blocks the RRS signal whether is generated due to normal or faulted input signals. The main objective of this SBCS AWP is to increase plant availability by avoiding unit trips provoked by uncontrolled CEA withdrawal incidents resulting from failures in the RRS.

In addition, a demand from any of the Quick Opening Channels activates the "TURBINE BYPASS DEMAND" Annunciator to alert the operator that the SBCS is, active and that this may be the cause of the AWP in effect.

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