NRC-90-0039, Application for Amend to License NPF-43,eliminating Requirement for Use of Rod Sequence Control Sys & Decreasing Power Level Setpoint Above Which Rod Worth Minimizer Sys Would No Longer Be Required

Application for Amend to License NPF-43,eliminating Requirement for Use of Rod Sequence Control Sys & Decreasing Power Level Setpoint Above Which Rod Worth Minimizer Sys Would No Longer Be Required

ML20043B201
Person / Time
Site:	Fermi
Issue date:	05/18/1990
From:	Orser W DETROIT EDISON CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20043B202	List: ML20043B203 NRC-90-0039, Application for Amend to License NPF-43,eliminating Requirement for Use of Rod Sequence Control Sys & Decreasing Power Level Setpoint Above Which Rod Worth Minimizer Sys Would No Longer Be Required
References
CON-NRC-90-0039, CON-NRC-90-39 NUDOCS 9005250070
Download: ML20043B201 (9)

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= t.6 May 18,71990 NRC-90-0039 U. S. Nuclear Regulatory Commission Attna . Document Control Desk

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Washington, D. C. 20555 Refe rence: Fermi 2

.NRC Docket No. 50-341 NRC License No. NPF '

Subjects. Propose,1 Technical Specification Change (License Amendment) - Removal of the Rod . Sequence Control System and Lowering of the Rod Worth Min'imizer Low Power Setpoint Pursuant to 10CFR50.90 Detroit. Edison Company hereby proposes to amend Operating License NPF-43 for- the Fermi 2 plant by incorporating?

the enclosed changes into the Plant Technical Specifications. - The.- .

proposed change eliminates the: requirement for use of: the Rod ' Sequence .

-Control System (RSCS) -and : decreases the power level .setpointi above,

• which the Rod Worth Minimizer (RWM) system would no longer be' required'.

.>: Detroit Edison has evaluated the proposed Technical Specifications

• I against the' criteria of 10CFR50.92 and - determined that no significant hazards consideration is involved. The Fermi" 2' Onsite. Review #

Organization has approved and the Nuclear Safety Review. Group; has.

'rev.iewed the proposed Technical Specifications and concurs with the  :

enclosed determinations. In accordance with 10CFR50.91, Detroit Edison:has provided a copy of this letter to the State of Michigan.

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'If you have -any questions, please contact .Mr. Glen Ohlemacher at (313)

~5 586-4275.  :

Sincerely, t

. Enclosure  ;

cc: A. B. Davis R. W. DeFayette W. G. Rogers J..F. Stang Supervisor, Electric Operators Michigan d" Public Service Commission - J. Padgett M/

9005250070 900518 DOW l

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USNRc f May 18,:1990 p NRC-90-0039'

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7 I, WILLIAM S. ORSER, do hereby af firm that the foregoing statements-l, ' are based on facts and circumstances which are true and accurate to-the best of my knowledge and belief.

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. WILLIAH S. ORSER Vice President Nuclear Operations -l t

<p On this / I day of N//22/ , 1990, before me 1 personally appeared William S. Orseb .b(in'g- first' duly sworn and says that 'he executed the foregoing as his free act' and deed.

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-NRC-90-0039 t-

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, INTRODUCTION.

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< Th6 purpose of this proposal is to eliminate the requirement for use of the Rod- Sequence Control System (RSCS) and to decrease the power level setpoint above which the Rod Worth Minimizer (RWM) System would

• no longer be required to be used f rom the existing 20% power requirement to a new 10%^ power level setpoint. These proposed ,

amendments to the Technical Specifications are based on and are  !

consistent with .the NRC Safety Evaluation Report issued to J. S.

Charnley December 27, 1987, which approved Amendment 17 of General Electric' Topical Report NEDE-24011-P-A " General Electric Standard 1 Application for Reactor Fuel". r The Rod Sequence Control System restricts rod movement to minimize the ..

-individual worth' of control rods to lessen the consequences of a Rod s Drop Accident (RDA). Control rod movement is restricted through the  ;

use of rod select.' insert, and withdrawal blocks. The Rod Sequence-j Control. System is a hardwired -(as opposed to a computer controlled). '

redundant backup 'to the. Rod Worth Minimizer. It is independent of the Rod Worth Minimizer in terms' of inputs and outputs but the two systems  ; l

are compatible. The RSCS is designed to monitor and block. when necessary, operator control rod- selection, withdrawal and insertion

. actions, and thus . assist in preventing significant control rod pattern errors which- could lead to a contral rod with a. high reactivity worth .,

(ifidropped). A significant pattern error is one of'several abnormal events all' of which must occur to have a RDA:which might exceed fuel' enthalpy criteria for the event. It was designed only: for possible <

mitigation of the RDA and is/ active only during low power operation (currently less than 20 percent power) when a' RDA might be

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significant. It provides rod blocks on detection of a significant pattern error.. It does not prevent:a RDA. A similar pattern control function is also performed by the RWM, a computer: controlled system. .  ;

In response to a topical report submitted by ,the BWR Owners' Group,

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the NRC staf f issued a letter with a supporting safety ' evaluation 1 approving 1) elimination of the RSCS while retaining the RWM to-

. provide backup to the operator-for ' control rod pattern control and 2)

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lowering the setpodnt for turnoff of RWM to 10% of rated thermal power -

f rom its current 20% level. (Letter dated December. 27, 1987. A. C.

Thadani. NRC to J. S. Charnley GE.

Subject:

Acceptance for Referencing of Licensing Topical-Report NEDE-24011-P-A. " General LElectric Standard Application for Reactor Fuel." Revision 8

. Amendment 17).

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~ EVALUATION The-NRC. safety evaluation approving the topical report concluded that the proposed modifications were acceptable provided:

1) The Technical Specifications (TS) should require provisions for minimizing-operations without the RWM system operable.;

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2) The' occasional necessary use of a second operator . replacement j should be strengthened by a. utility review of relevant procedures, related forms and quality control to assure that' the second operator provides an effective and truly independent monitoring process. A' discussion of this review should. accompany the request for RSCS' removal.

3)' Rod patterns used should be at least equivalent to Banked Position Withdrawal Sequence '(BPWS) patterns.

With respect to item 1) above, the proposed TSs submit ted with this- ,

amendment application allow only. one reactor startup per calendar year with the RWM unavailable prior. to or during the withdrawal of the first 12. control rods. This will ensure that' operations with the RWM

. system inoperable- are minimized.

These provisions are modeled. af ter the provisions found by; the NRC staff to be acceptable for the lead plant for the application.of the- . 1 results of the topical- report.; The provisions ~ address the need to

j promote ef fective maintenance of the RWM by severely limiting operation with -the system ' bypassed. Commencement of a reactor startup ,

with an inoperable RWM is -generally not allowed, with's once' per 4 calendar year exemption to allow for unusual or abnormal' situations.  ;

However; once a. reactor startup has commenced- and significantly progressed, specifically, af ter 12 rods are fully withdrawn. the evolution may be_ completed using the independent verifier provisions.

Detroit Edison believes that these provisions provide strong incentive i for RWM maintenance without engendering excessive' operational' restrictions and that, therefore, item 1) is adequately satisfied.

With respect to item' 2) above, the requirements for a rod motion verifier and the specified actions expected-of the verifier are proceduralized.- System Operating Procedure.(SOP) NPP-23.608, " Rod Worth Minimizer,". covers the requirement to use a verifier in accordance with the TS requirement when the RWM is bypassed. SOP NPP-23.623. " Reactor Manual Control, CRD, and Rod Sequence Control Systems," covers the actions expected of reactor operators and verifie rs.

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Included are:

.a) Procedures for control of changes to Rod Pull Sheets to ensure

. that correct pull sheets are used.

b) Separate Rod Pull Sheets for the operator and verifier. ' ,

c) Explicit instructions to the operator and verifier are contained in a Rod Pull Cover Sheet. Each operator and verifier must read and acknowledge by signature that the cover sheet hac been read each time prior to pulling rods .while below the RWM low power setpoint, d)- .7he above instructions include explicit instruction ~ to the .

verifier as to how and where to verify. both proper rod selection

. and proper rod positioning by the. operator.

' Detroit Edison believes that these controls ensure an effective and independent monitoring process and that, therefore, item 2) is '

. satisfied.

With . respect to item 3) above, Fermi 2 TS Surveillance Requirement 4.1.4.1.d requires that the BPWS pattern be verified to be correctly loaded into the RWM ' computer as a condition for RWM operability. This satisfies item 3) above.  !

Detroit Edison believes that the requirements of the NRC safety t evaluation-of December 27, 1987 have been' satisfied and therefore, the proposed changes are acceptable. Attached are proposed TS change. ,,

pages consistent with the NRC safety evaluation.- The TS changes primarily -involve changes to the RWM TS as described- above and  ;

editorial changes.concerning the elimination 'of the RSCS. '

TS 3/4.1.3.7, Control Rod- Position Indication, currently contains special action requirements for inoperable " Full-in" and/or " Full-out" indicators.. These actions.are associated with these position 1; indicators' input. into the RSCS logic. With the proposed elimination :j of RSCS the special actions for these indicators are no longer needed j and have been eliminated. '

SIGNIFICANT HAZARDS CONSIDERATION i

In accordance with 10CFR50.92, Detroit Edison has made a determination E

'that the proposed amendment involves no significant hazards considerations. To make this determination, Detroit Edison must establish that-operation in accordance with the proposed amendment would not: 1) involve a significant increase in the probability or C

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Page 4 consequences of an accident previously evaluated, or 2) create the

. possibility of a new or different kind of accident from any accident

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previously evaluated, or 3) involve a significant reduction in a margin of safety.

4 g' ' The proposed change to delete the RSCS and reduce the RWM low power .;

setpoint 'from 20% to 10% power does not: '

- 1)- Involve a significant increase in the probability or consequences- s of an accident'previously evaluated.

Deleting the RSCS and changing the low power setpoint of the RWM has.no-effect'.on the probability of any previously evaluated accident becauseL these systems play. no role in any -accident

. initiating mechanism. . These systems act to mitigate the consequences.of the rod drop accident. (RDA); however, the +

probability of'an RDA is dependent only on the control rod. drive system and: mechanisms themselves, and.not in any way;on the RSCS or RWM. Therefore. the change does not involve a.significant '

increase in the probability of an accident previously evaluated.

The . consequences of an RDA as evaluated will not be affected by '

this modification. The BWR Owners' Group sponsored study ,

(NEDE-24011-P-A)cof the RDA has concluded that the RSCS is I unnecessa ry. This study was approved by the NRC in a safety 1 evaluation dated December 27. 1987.

The RSCS duplicates the function:of theLRWM.. So long as the RWM '

is . operable, the RSCS 'is not needed since the RWM prevents control rod pattern , error. . In:the event the RWM is out of ..

service, the proposed Technical Specifications require that. d control rod movement and compliance 'with the prescribed control' rod pattern:be verified by a second licensed operator or j technically qualified member of L the technical staf f. The-verification process is. controlled procedurally. I,n addition, to further minimize control rod movement at low power with the RWM .

out of = service. .the proposed Technical' Specifications will permit <

only one plant start-up per calendar year with the RWM out of service prior to or. during the withdrawal of the first twelve control rods. The above substantiates the conclusion that there:

will be no increase in the consequences of an RDA as a result of eliminating the RSCS.

There will also be no increase in the consequences of an RDA due

• to lowering the RWM setpoint from 20% to 10% power. The effects of an RDA are more severe at low power levels and are less severe as power level increases. Although the original calculations j

v l'. ~ Enclosure to' NRC-90-0039 Page 5' showed that no significant RDA could occur above 10% power., the

- NRC required that the. generic BWR Technical Specifications be , l written to require operation of the RWM below 20% power in order  ;

~to account for uncertainties in the analysis. .Recently, more refined calculations conducted for the.NRC have shown that even u :h the maximum single contrc1' rod position- error. and most .  ;

s meiple control rod error patterns, the peak fuel rod enthalpy- -

reached during an RDA from these control rod patterns would not~ ,

exceed the .NRC limit of 280 cal /gm for RDAs above ~10% power,

. confirming the original GE analyses. Hence, lowering the RWM. ,

setpoint from 20% to 10% will not result in an increase in the consequences-of an RDA. The previously referenced NRC safety -

evaluation has concluded that this RWM setpoint reduction is '

acceptable. >

2) Create the possibility of a new or different kind of accident ,

from any accident previously evaluated.

Operation of the RSCS and RWM cannot'cause or prevent an accident.- They function to minimize the consequences of an RDA.

The RDA is already evaluated in the UFSAR, and the-ef fect of this i proposed change on the analyses is discussed in Item 1) above.

Elimination of the RSCS and lowering the RWM setpoint will have

- no1 1mpactJon the operation of any other systems, and hence would not contribute to a malfunction in;any other equipment nor create j

. the possibility for an- accident to occur which has not already:

been evaluated. l t

3) Involve's significant reduction in a margin of safety..

F Elimination of the.RSCS will not lower the margin of safety-for.

the reasons discussed' in-Item ~1 above and summarized below:

a) An extensive NRC study has determined that the possibility .of s an RDA resulting in unacceptable consequences is so low as to I

' negate the requirement for the RSCS.

b) Recent calculations have determined that the consequences of 1 an RDA are acceptable above 10% power.  ;

c) . The RSCS is redundant in function to the RWM. Eliminating the RSCS does not eliminate the control rod pattern monitoring function performed by the RWM. '

d) To ensure that the RWM will be in service when required, the RWM Technical Specification will be revised to allow only one

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startup per calendar year with the RWM out of service prior to or .during the withdrawal of the fitst twelve control

' rods. If the RWM is out of service below 10% power, control

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rod movement and compliance with prescribed control rod j i

patterns will be verified by a second licensed . operator or

- technically qualified member of the technical staf f. ]

There is no significant reduction in the margin of safety i r", resulting f rom lowering the RWM .setpoint from 20% to 10% power' l because calculations have shown that even with the maximum single l control rod position error, and most multiple error patterns, the peak fuel rod enthalpy curing an' RDA from these patterns would-not exceed the NRC limit (280 cal /gm) above 10% power. -

. In summary. GE has ~ provided technical justification for the {

proposed changes in the Topical Report NEDE-24011-P-A and associated references which justify the acceptability of the d proposed changes, i

The NRC has reviewed and accepted the .GE analysis and provided i guidelines for licensees wanting to make the changes proposed in.  !

NEDE-24011-P-A and approved in-the NRC SER issued December 27, 1987 to J. S. Charnley of General: Electric.

The proposed changes are consistent with those approved in- the NRC SER and the guidelines setforth therein. Therefore, there is ,

no significant reduction in a margin .of safety. .!

The NRC has provided guidance concerning.the application of the [

standards for determining whether a license-amendment involves any significant hazards consideration by providing examples (51FR7744) of amendments that are considered not likely to involve significant  !

hazards considerations. Example (iv) is a relief granted-lupon _}

demonstration of acceptable operation from an operating restriction 'l that,was imposed because acceptable operation was not yet . .. .

demonstrated. This assumes that the operating restriction and the criteria.to be applied to'a request for relief have.been established. '

.in a. prior review and that it is justified in a satisfactory way that the criteria have been met. This proposed Technical Specification change request is similar to example (iv) in that the NRC has reviewed 1 the proposed change and established criteria for removing the RSCS and lowering the RWM low power setpoint. The proposed changes are in compliance with the NRC criteria.

R Based on the above. Detroit Edison has determined that the proposed amendment does not involve a significant hazards consideration.

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i ENVIROlGGDrfAL ' IMPACT Detroit' Edison has reviewed the proposed Technical Specification changes against the criteria of 10CFR51.22 for environmental l considerations. The proposed change does not-involve a significant hazards' consideration, nor'significantly change the types' or

significantly increase the _ amounts of ef fluents that may be released of fsite. nor significantly increase individual or cumulative occupational radiation exposures. Based on the foregoing Detroit l Edison concludes that the proposed ~ Technical Specifications do meet '!

the criteria given in 10CFR51.22(c)(9) for a categorical exclusion from the requirements for an Environmental Impact Statement. ,

CONCLUSION f

Based on the evaluation aboves. 1) there is reasonable assurance that: ..;

the health and safety:of the public will not be endangered by. '

operation in.the proposed . manner, and 2) such activities will be ,

conducted in compliance with the Commission's regulations and proposed amendments will not be inimical to the common defense and security or to the health and safety of the public.

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