NRC-89-0039, Application for Amend to License NPF-43,changing Tech Specs Re source-range Monitors to Permit Core off-loading During First Refueling Outage

Application for Amend to License NPF-43,changing Tech Specs Re source-range Monitors to Permit Core off-loading During First Refueling Outage

ML20244A671
Person / Time
Site:	Fermi
Issue date:	04/03/1989
From:	Sylvia B DETROIT EDISON CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20244A672	List: ML20244A844 NRC-89-0039, Application for Amend to License NPF-43,changing Tech Specs Re source-range Monitors to Permit Core off-loading During First Refueling Outage
References
CON-NRC-89-0039, CON-NRC-89-39 NUDOCS 8904180127
Download: ML20244A671 (9)

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x 3 3,z 1 s  ; 8. Rdph Sylv'la

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g f April' 3,1989 NIC-89-0039 U. S. Nuclear Begulatory Commission 3 Attn Document Control Desk L' ' washington, D.' C. 20555-

1) Fermi 2 Beferences:

NRC Docket No.- 50-34)

NRC License No. NPF-43 p 2) General' Electric Nuclear Services Information Letter, SIL No.: 478, dated December 16, 1988 Subjects. Proposed Technical. Specification Change (License Amendment) - Source Range Monitoring Instrumentation

-(3/4.3.6. 3/4.3.7.6, 3/4.9.2)

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 proposal- requests changes' to Technical Specifications relating .to the -

Source Range Monitors. (SBM) to permit complete core off-loading during the first refueling outage. The propnsal also increases the minimum signal-to-noise ratio required for a reduced SPM minimum count rate requirement and eliminates a related Technical Specification provision which is no-longer needed. An associated change to the Bases is also i included. >

Detroit Edison has evaluated the proposed Technical Specifications  ;

against the criteria of 10CFR50.92 and determined that no significant hazards consideration is involved. The Fermi 2 Onsite Review y ' Organization has approved and the Nuclear Safety Review Group has reviewed the proposed Technical Specifications and concurs with the enclosed determinations. In accordance with 10CPR50.91, Detroit R11 son has provided a copy of this letter to the State of Michigan. l AW I(

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

-586-4275.

j.,, Sincerely,

o Enclosure cc 'A. B. Davis R. C. Knop W. G. Rogers J. R. Stang.

Supervisor, Advanced Planning and Review Section, Michigan Public Service Commission P

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I J-IF I, B. FALPH SYLVIA, do hereby affirm that the foregoing statements 'are based on facts and circumstances which are true and accurate to the best _of my knowledge and belief.

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Senior Vica President

.On this dual day of 0001 ,1989, before me personally appeared B. Ralph Sylvia, being first duly sworn and says that he executed the foregoing as his free act and deed.

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Notary Public-KAREN M. REED Notary Public, Monme County, Mj:h,  !

My Commission Expires May 11,19)J 5

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Enclosure to NFC-89-0039 Page 1 BACKGROUf0/b1SCUSSION Detroit Edison has scheduled the first refueling outage for Fermi 2 to begin'during Septenber,1989. During the outage, conplete core off-loading is planned in order to more efficiently complete and accommodate refueling outage work. The removal of the assenblies Mjacent to the Source Range Monitors (SR4s), which are the last fuel assemblies to be removed, would cause the loss of SR4 detector count rate. This is contrary to the requirements of Specification 3/4.9.2, Surveillance Requirement 4.9.2.c, which requires a mininum SR4 detector count rate be maintained at all times during CORE ALTERATIONS. This proposal requests a revision to the requirement for a mininum SR4 count rate so that when sixteen or fewer fuel assenblies, each of which are installed in one of the four positions j directly adjacent to one of the four permanently installed SR4 nuclear detectors fuel assenblies (four fuel assenblies surrounding each SR4 detector), are in the core the mininum SR4 count rate requirement does not apply. This change is necessary to allow complete core off-loading.

The current Technical Specification requirements are based upon the use of "Special Movable Detectors" connected to the " normal sri circuits". Experience at other BWR stations indicates that these "Special Movable Detectors", i.e. , " Fuel LoMing Chant >2rs" (FICc) do ,

not function as originally anticipated.

This experience has shown that the FICs produce signal variations because of the lack of fixed core geometry during refueling operations

nd tend to saturate because of gamma flux. Further, because the FICs ara attached in a temporary manner to facilitate ease of relocation, thair use increases the risk of dropping them into the vessel. The FICs have been found to be unreliable, and increase the probability of ,

having a loose object fall in the reactor. i Under the proposed requirements, the SIE count rate requirements would not apply if sixteen or fewer fuel assenblies, each of which are installed in one of the four positions directly Mjacent to one of the four permanently installed SIN nuclear detectors, are in the core.

During core off-loMing (without FICs), the fuel would be removed with the mininum count rate requirement being maintained until the only fuel remaining would be directly Mjacent to an SR4. At this tine, the remaining fuel would be removed under the proposed provisions for  ;

exenption from the mininum count rate requirement, i l

During core reloading the new provisions allow the loading of I irrMiated fuel directly adjacent to the permanently installed SRI l nuclear detectors. This will establish a sufficient SR4 count rate to I allow further fuel loading to proceed. Fuel loMing patterns are l l 1

l Enclosure to )

10C-89-0039 l Page 2 selected to ensure a continuous multiplying medium between an OPEPABLE Sm and the location of any CORE ALTERATIONS. This enhances the ability of the Sm to detect any abnormal reactivity addition. ,

The Sm system provides neutron flux information during startup and  ;

low flux level operations. The SM also nonitors neutron flux level during refueling operations, during the approach to criticality, and nonitors neutron flux through the overlap into the Intermediate Range. The SR4 system progides four channels of neutron flux information from 0.1 to 10 counts per second and four channels of reactor period from -100 to +10 seconds. The S m system also initiates Rod Withdrawal Blocks via the Reactor Manual Control System and, if the Reactor Protection System " shorting links" are renoved, a ,

Reactor Scram on a High Neutron Flux signal. '

l The basis for requiring a minimum count rate for the Sms is to provide continuous assurance that the channel is properly functioning and nonitoring neutron flux. The minimum count requirement is sufficiently high enough to assure that the signal is being generated by a neutron field and is not actually channel electrical noise.

The proposed amendment allows the mininum count rate requirement to be suspended under the highly restricted condition where the only fuel in the core is directly adjacent to a permanently installed SR4 nuclear detector. The fuel supplier, GE Nuclear Energy, has evaluated this condition and has determined that criticality is not possible in this configuration (four fuel assemblies surrounding each Sm detector) because of the neutron leakage. This is true even if the configuration is uncontrolled and optinum neutron noderation conditions and worst-case fuel reactivity are assumed.

The refueling system interlocks continue to be required during all CORE ALTERATIONS, including those involving the sixteen fuel assenblies directly adjacent to the permanently installed SR4 nuclear detectors, which are proposed to be allowed with the Sm count rate j below mininum. These interlocks, along with the associated refueling i procedures, provide additional assurance that irsadvertent criticality does not occur during proposed operations with GR4 count rate below mininum. These interlocks and procedures ensure the control rods are and remain inserted during such operations. S'he refueling interlocks are not affected by the loss of SR4 channels due to loss of mininum count rate.

The reactor period circuit provides indication and alarm functions for the rate of change of reactor power as neasured by the SPM. These functions are designed to provide operational information during reactor startup. Therefore, the impact on the reactor period i

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Enclosure to NBC-89-0039 Page 3 ,

functions of the SR4 system from allowing SRI count rate to fall below l the mininum requirement during certain CORE ALTERATIONS is not of  !

concern.

The SR4 rod block functions are provided to ensure that when necessary SR4 indication exists prior to rod withdrawal. These rod block functions are required to be OPEPABLE per Specification 3.3.6 in OPERATIONAL CONDITION 5. Although this proposal exenpts the SR4 channels from mininum count rate requirements during certain CORE ALTERATIONS, the rod block functions are still required. The Sai  !

downscale rod block will actuate and provide additional assurance that  !

rod notion does not occur without SR4 nonitoring capability.

Therefore, the inpact of the change on the SR4 rod block functions is not of concern.

In summary, the proposed changes which allow core off-loading and reloading without the use of FICs will result in inproved safety because: ,

o The SRis are more reliable than FICs o The risk of dropping loose objects into the reactor is reSuced by eliminating the use of Firs o The elimination of the SR4 count rate requirement when there j are sixteen or fewer fuel assenblies, each of which are installed in one of the four positions directly adjacent to i one of the four permanently installed SRI nuclear detectors (four fuel assenblies surrounding each SR4 detector),

installed in the core does not, as discussed above, result in degradation of any feature necessary for safety, i As discussed above, the Firs have been found to be less desirable than the normal SR4 detectors for use during CORE ALTERATIONS. Eowever, instances may occur where the use of FICs cannot be avoided.

Therefore, provisions for the use of FICs are proposed to remain in the Technical Specifications.

The Technical Specification requirements for mininum count rate specify that a count rate of at least 3 counts per second (cps) be present unless a signal-to-noise (S/N) ratio of greater than 2 exists, in which case 0.7 cps is the specified mininum count rate. Recent studies by General Electric, discussed in Reference 2, have indicated that an S/N ratio of at least 20 is required to reduce the mininum count rate to 0.7 cps. The increased S/N ratio is necessary to maintain the original level of source range nonitoring uncertainty assumed by a 3 cps mininum count rate. Based upon the above, Detroit ),

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Enclosure to NIC-89-0039 Page'4 Edison is proposing to increase the S/N ratio necessary' for a mininum SM4 count rate requirement of 0.7 cps- to 20. This change will restore the margin of safety to the level originally assumed.

The provision is also proposed to be reworded with the 3 cps requirement specified in the body of the specifications and the 0.7 '  !

cps provision being included in a footnote. . This change is strictly administrative and proposed to enhance the consistency and clarity of ,

the Technical Specifications. '

' AmerrJment 1 to the Fermi 2 Technical Specifications provided j'

. provisions necessary for the replacement of the start-up neutron

-sources early .in the first fuel cycle. The need for these provisions has passed. - Therefore, Detroit Edison is proposing to eliminate the' Amendment' 1 provisions as part of. this proposal.

SIGNIFICANT HMNDS COPEIDERATION

. In accordance with 10CRR50.92, Detroit Edison has made' a determination that the proposed amendment involves no significant hazards 1 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 consequences of an accident previously evaluated, or 2) create the possibility of a'new or different kind of accident from any accident previously evaluated, or 3) involve a significant reduction in a margin of safety.

The proposed change to eliminate the SR4 count rate requirement when sixteen or fewer fuel assenblies, each directly adjacent to a normal SR4 detector (four fuel assemblies surrounding erh SR4 detector), are in the core does not: .j

1) Involve a significant increase in the probability or consequences of an accident previously evaluated. The proposed change allows the mininum count rate requirement to be suspended under the highly restricted condition where the only remaining fuel is  !

directly adjacent to an SR4. This configuration has been  ;

evaluated and criticality found to be precluded by the amount of neutron leakage; even without the presence of control rods, under ,

optimum neutron moderation conditions, and with the worst-case  !

fuel reactivity. Since criticality is not possible, the change i has no effect'on the probability or consequences of an inadvertent f criticality during refueling. The change does not affect the  !

initiating mechanisms or the means of mitigation for any other {

evaluated accident and thus can not affect the probability or i consequences of these accidents.  !

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2) Create the possibility of a new or different kind of accident from any accident previously evaluated. The change eliminates the requirement to maintain a source of information (SR4 count rate) when the need for the information is no longer required (since criticality is precluded as discussed in 1 above) . The elimination of a requirement for an unnecessary source of information can not create a new accident scenario. Therefore, i the change does not create the possibility of a new or different kind of accident from any mcident previously evaluated.

3) Involve a significant reduction in a margin of safety. Since the  !

requirement for SR4 count rate information is eliminated for conditions when it has no safety significance (since criticality is precluded as discussed in 1 above), the change has no inpact on a margin of safety. By eliminating the need for FICs, which are less reliable than the normal SH4 detector and subject to being dropped into the reactor vessel, the change may increase the overall margin of safety.

The proposed change to increase (from 2 to 20) the S/N ratio requira3 to reduce the SH4 mininum count rate to 0.7 cps does not:

1) Involve a significant increase in the probability or consequences of an meident previously evaluated. The change is proposed to reflect recently performed studies which indicate that to maintain the assumed level of SM4 nonitoring uncertainty the S/N ratio requirement nust be increased. Thus, the change acts to ensure that the assumptions of the accident evaluations are unchanged and, therefore, the probability or consequences of the evaluated accidents remain unchanged.

2) Create the possibility of a new or different kind of accident from any accident previously evaluated. The change solely changes the criteria by which an SH4 is considera3 OPERABLE when the indicata3 count rate is between 0.7 and 3 cps. Since the ACTIONS taken for an SR4 inoperability are not changed, the change does not create the possibility of a new or different kind of accident.

3) Involve a significant reduction in a margin of safety. The change restores the margin of safety to the level originally assumed and therefore does not represent a reduction in any margin of safety.

The rewording of the provisions for reducing the mininum required SH4 count rate and the elimination of the provisions for replacement of the start-up neutron sources are administrative changes which fall under exanple (i) of Exanples of Amendnents Not Likely to Involve l Significant Hazards Considerations listed in 51 FR 7751. The changes,

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,. 1-Enclosure'to',

NIC-89-0039 Page 6-due to. th'eir strictly administrative nature, do~ not affect the manner;

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F of plant operation or the evaluation of any accident. Therefor'e, they i; do not:

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. Involve a significant increase in the probability or consequences of an a:cident previously evaluated.

o Create the possibility of'a new or different kind of accident from any accident previously evaluated. -

o Involve a significant reduction in a margin.of safety.:

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

EWIHONEN5L INPACT Detroit Edison has reviewed the proposed Technical Specification changes against the criteria of 10CFR51.22 for environmental considerations. The proposed change does not. involve a significant hazards consideration, nor significantly change' the- types or..

significantly increase the amounts of effluents that may be released offsite, nor significantly increase individual or cumulative occupational radiation exposures. Based on'the foregoing,, Detroit Edison concludes that the proposed Technical Specifications do neet -

the criteria given in 10CFR51.22(c)(9) for a categorical exclusion

'from the requirements for an Environmental Impact Statement.

COPCWSION

-Based on the evaluation above: 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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