NG-93-4290, Application for Amend to License DPR-49,consisting of Request for TS Change (RTS-260),clarifying Existing TS Bases Re Long Term APRM Bypass

Application for Amend to License DPR-49,consisting of Request for TS Change (RTS-260),clarifying Existing TS Bases Re Long Term APRM Bypass

ML20058L651
Person / Time
Site:	Duane Arnold
Issue date:	12/07/1993
From:	Franz J IES UTILITIES INC., (FORMERLY IOWA ELECTRIC LIGHT
To:	Murley T NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM), Office of Nuclear Reactor Regulation
Shared Package
ML20058L653	List: ML20058L659 NG-93-4290, Application for Amend to License DPR-49,consisting of Request for TS Change (RTS-260),clarifying Existing TS Bases Re Long Term APRM Bypass
References
NG-93-4290, NUDOCS 9312170128
Download: ML20058L651 (6)

Text

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-i Iowa Electric Light and Power Company l 1

1 l

l JOHN F, FRANZ, JR. December 7, 1993  ;

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NG-93-4290 j 1

Dr. Thomas E. Murley, Director.

Office of Nuclear-Reactor Regulation j U. S. Nuclear Regulatory Commission -i TAttn:XIDocdmeHETC6EEE61Eposkv Mail Station Pl-137 Washington, DC 20555 j

Subject:

Duane' Arnold Energy Center .

Docket No: 50-331 Op. License No: DPR-49' .

Request for Technical Specification.

Change (RTS-260): Clarifi'ation c of TS Bases regarding long. term APRM-Bypass! .i File: A-117, C-51 ,

Dear Dr. Murley:

j t

In accordance with the Code of Federal Regulations, Title 10,  ;

Sections 50.59 and 50.90, Iowa Electric Light and' Power Company- .

(IELP) hereby requests revision _to-the Technical Spe'cifications [

(TS) for the Duane Arnold Energy Center.(DAEC).- {

The proposed changes clarify the existing TS Bases regarding.the l acceptability of bypassing one Average Power RangejMonitor (APRM) -l '

channel per protection trip-system for reasons other than.those specifically listed. In addition, an editorial change isLbeingf made to the Bases for the Intermediate Range' Monitors (IRMs) for consistency. These changes are consistent with'the existing TS and plant design basis and are described.in more detail in-Attachment 1. The practice of bypassing;one APRM channe1~per' s .

trip system was discussed at a management = meeting between'NRC i Region III, NRR and IELP.in September of 1992. y This letter contains no new commitments, nor does it' modify any.

q previous commitments.

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l This application has been reviewed by the DAEC Operations l Committee and the DAEC Safety Committee.. .A copy-of this submittal, along with the no significant hazards. considerations; analysis, is being forwarded to our appointed state official-pursuant to 10 CFR 50.91.

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l-I Dr. Th'omas E. Murley 1 FG-93-4290  :

Lecember 7, 1993

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Should you have any questions regarding this matter, please .

contact this office.

• j This letter is true and accurate to-the best of.my. knowledge and 3 belief.

IOWA ELECTRIC LIGHT AND POWER. COMPANY- j By M -[

John-F.1Pranh .

Vic(' President, Nuclear State of Iowa ,

l (County) of Linn Signed and sworn to before me-on this . day of- ///// ,

1993, by Ag z.s- ..

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Notary Pd llc in and for the State of Iowa  ;

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Commissi6h E'xpires JJ s$[/VVN r

t JFF/TWP/pjv' Attachments: 1) Evaluation of' Change with Respect.to 10LCFR 50.92 j

2) Proposed Change.RTS-260 to theLDuane~ Arnold Energy Center Technical Specifications '

3) Safety Assessment

4) Environmental Consideration.:  !

cc: T. Page L. Liu  :

L. Root t R. Pulsifer (NRC-NRR) J J. Martin (Region III) l S. Brown (State of Iowa) "I NRC Resident Office DCRC i

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.RTS-260 Attachment 1 to NG-93-4290 Page 1 of 4 EVALUATION OF CHANGE WITH RESPECT TO 10 CFR 50.92

Background:

The Average Power Range Monitoring (APRM) subsystem has six APRM channels, with three APRM channels in each Reactor Protection i

System (RPS) trip system. Each APRM channel receives input from twenty Local Power Range Monitors (LPRMs). Since there are only eighty LPRMs in the core to provide input to the APRMs, some APRM channels share inputs from the same LPRMs. APRM channels A and B .

share inputs from the same 20 LPRMs;. channels C and D share  !

inputs from another 20 LPRMs. APRM channels E and F each receive l inputs from 20 separate LPRMs. (See figure on page 4 of ,

Attachment 1.)

l The DAEC was designed and constructed to have a dual channel type l RPS. The system is made up of two independent trip systems (A ,

j and B), each of which is divided into three subchannels (A1, A2, '

l A3 and B1, B2, B3). The A3 and B3 subchannels have inputs from l the manual scram push buttons and the reactor mode _ switch. The four remaining subchannels receive input from independent instrument channels which monitor critical parameters. The outputs of the subchannels are combined to provide a 1-out-of-2 twice scram logic. The Al, A2, B1 and B2 subchannels each  ;

receive inputs from a dedicated APRM. In addition to the dedicated APRM input, the subchannels in each trip system also receive input from another APRM which they share. In the A trip i system, this third APRM provides input to the Al and A2 '

subchannels. In the B trip system, the third APRM provides input to the B1 and B2 subchannels. (See figure on page 4 of Attachment 1.) This third APRM serves, in effect, as an installed spare and is used to maintain the 1-out-of-2 twice logic when one of the APRMs becomes inoperable or is removed from service for other-reasons. The Duane Arnold Energy Center (DAEC)

Technical Specifications (TS) (Section 3.1) requires that two APRM channels in each trip system be operable. I General Electric NEDO-10139, " Compliance of Protection Systems to Industry Criteria: General Electric BWR Nuclear Steam Supply System," states in subsection 2.2.17.1, "In order to meet the general functional requirement, sufficient APRM and IRM channels are provided in the design to permit continuous bypass of one -

APRM channel in each-trip system-and continuous bypass of one-IRM i in each trip system._ The remaining APRM and IRM channels in service are adequate in number _and in their spatial coverage of -

the reactor core to comply with the IEEE-279 requirements."

If a spike were to occur in a LPRM that has a shared input to either APRMs A and B or APRMs C and D, the potential for a full scram from a single failure could be introduced. The APRM Operating Instruction was changed to require that APRM combinations of A and D or C and B be maintained in the bypass position during normal operation. This ensures that an APRM that shares LPRMs with another APRM in the opposite RPS trip system i will not be susceptible to unnecessary reactor scrams due to LPRM spiking.

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.RTS-260 Attachment I to NG-93-4290 Page 2 of 4 The current wording of the Bases for TS 3.1 could be construed as being all inclusive, implying that the only permissible reasons for bypassing an APRM are those listed (i.e. maintenance, testing or calibration). In fact, there are other valid reasons for bypassing an APRM such as that described above. '

The proposed changes are consistent with the amendment previously approved for the Monticello Nuclear Generating Plant (Amendment No. 83, approved August 18, 1992, to Facility Operating License No. DPR-22, Docket No. 50-263).

Iowa Electric Light and Power Company, Docket No. 50-331, Duane Arnold Energy Center, Linn County, Iowa Date of Amendment Request: December 7, 1993 Description of Amendment Request:

The proposed license amendment deletes the list of specific conditions in the Bases for TS 3.1 to clarify that bypassing of the APRMs is not limited to the situations currently listed and that other situations are acceptable (including long-term bypass), provided the minimum number of operable channels specified in the TS is maintained. In addition, an editorial change is being made to th? IRM channel bypass description in the ,

Bases to clarify that one channel may be bypassed "in each trip '

system."

Basis for proposed no significant hazards consideration:

The Commission has provided standards (10 CFR 50.92(c)) for determining whether a significant hazards consideration exists in connection with an amendment. A proposed amendment to an operating license for a facility involves no significant hazards consideration if operation of the facility in accordance with the proposed amendment would not (1) involve a significant increase in the probability or consequences of an accident previously evaluated; (2) create the possibility of a new or different kind of accident from any accident previously evaluated; or (3) i involve a significant reduction in a margin of safety.

After reviewing this proposed request for Technical Specification change, we have concluded:

1) The proposed amendment will not increase the probability or consequences of an accident previously evaluated. The proposed amendment clarifies that it is acceptable to bypass an APRM channel in each trip system for extended periods of time. As discussed above, GE NEDO-10139 verifles that the

. design requirements of IEEE-279 are satisfied when one APRM l

channel is bypassed in each trip system. This information is reiterated in UFSAR 1.8.22. As stated in UFSAR 7.6.1.7.6, the design of the RPS system allows one bypass ,

and one random failure in each trip system while still satisfying the RPS safety design basis. The TS 3.1 Bases also state that each protection trip system has one more ,

APRM than is necessary to meet the minimum number required '

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l RTS-260 Attachm:nt 1 to ,

NG-93-4290 i Page 3 of 4 l per channel. The change to the Bases statement regarding  !

IRM bypasaing is editorial _in nature and merely clarifies  !

that the statement pertains to each_ trip system,_which is consistent with TS 3.1 and the DAEC design basis. Thus, the clarification and the editorial change will not increase the probability or-consequences of an accident previously ,

evaluated.

2) The proposed amendment will not create the possibility of a new or different kind of accident from any accident' previously evaluated. UFSAR Section 15 discusses accident analyses and the assumptions that were made for each scenario. The proposed change to make clear that manual bypass of the APRM channels under conditions other than those now specifically listed is acceptable and will not affect any of the design basis accident analyses nor allow any credible, non-evaluated accident to occur. The wording added to the Bases regarding the IRM channels is consistent with the DAEC TS and the design basis and is added for clarity. Sufficient redundancy in the system is provided, as discussed above, such that no new or different kinds of accidents than those previously evaluated are created.

3) The proposed change will not involve a significant reduction in the margin of safety. TS Table 3.1-1, Reactor Protection System Instrumentation, requires that two APRM channels per trip system be operable. Each trip system has one more APRM than is necessary to meet the minimum number required. This allows bypassing one APRM channel per trip system. The . ,

design of the APRM bypass switch is such that no more than ,

one APRM channel per trip system can be bypassed manually at any given time. The change to the IRM channel Bases clarifies the intent of the Bases regarding the i acceptability of bypassing one IRM channel per trip system.  ;

The changes are consistent with the DAEC TS,_ design _ basis and current operating practice and do not significantly reduce the margin of safety.

Based upon the above, we conclude that the proposed amendment- j i

does not involve a significant hazards consideration.

I Local Public Document Room Location: Cedar Rapids Public Library, 500 First Street SE, Cedar Rapids, Iowa 52401 i Attorney for Licensee: Jack Newman, Kathleen H. Shea, Newman and Holtzinger, 1615 L Street NW, Washington, D.C. 20036

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.RTSh60 ' Attachment 1 to '

NG-93-4290 '

Page 4 of 4  ;

i APRM SCRAM LOGIC (SIMPLIFIED DIAGRAM). .

SCRAM SIGNAL f

RPS Cl-I NNEL A RPS CHANNEL B },

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SUBCHANNEL A1 SUBCHANNEL A2 SUBCHANNEL B1 SUBCHANNEL B2

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i APRMA 1, APRM E \ \ APRM C 1 APRM B 1 APRM F \

' APRM D 5

l LPRMs LPRMs LPRMs LPRMs .

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