U-602406, Application for Amend to License NPF-62,changing TS 3.3.2.1, Control Rod Block Instrumentation to Revise Two SRs & Associated Notes for Rod Withdrawal Limiter Mode of Rod Pattern Control Sys
| ML20078N262 | |
| Person / Time | |
|---|---|
| Site: | Clinton  |
| Issue date: | 02/10/1995 |
| From: | Jackie Cook ILLINOIS POWER CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| Shared Package | |
| ML20078N264 | List: |
| References | |
| JGC-066-95, JGC-66-95, L47-95(02-10)LP, L47-95(2-10)LP, U-602406, NUDOCS 9502150242 | |
| Download: ML20078N262 (8) | |
Text
f Ilknois Power Company
.. c Chnton Power Station P.O. Box 678 Chnton. IL 61727 Tel 217 935-5623
.- Fax 217 935-4632
. John G. Cook Vice President P@WER u-602.
L47-95(02 -10 )LP 8E.100a JGC-066-95 February 10, 1995 Docket No. 50-461 10CFR50.90 Document Control Desk Nuclear Regulatory Commission Washington, D.C. 20555
Subject:
Clinton Power Station Proposed Amendment of Eacility Ooerating License No. NPF-62 (LS-95-001)
Dear Sir:
Pursuant to 10CFR50.90, Illinois Power (IP) hereby applies for amendment of Facility Operating License No. NPF-62, Appendix A - Technical Specifications, for Clinton Power Station (CPS). This request consists of proposed changes to Technical Specification (TS) 3.3.2.1, " Control Rod Block Instrumentation," to revise two surveillance requirements and their associated notes for the Rod Withdrawal Limiter (RWL) mode of the Rod Pattern Control System. This request will confoim these requirements to their original bases and eliminate the potential for unnecessary power reductions.
A description of the proposed changes and the associated justification (including a Basis For No Significant Hazards Consideration) are provided in Attachment 2. A marked-up copy of the affected pages from the current Technical. Specifications is provided in Attachment 3. In addition, a marked-up copy of the affected pages from the Technical Specification Bases is provided in Attachment 4. Upon approval of this request by the NRC, IP will revise the CPS TS Bases in accordance with CPS TS 5.5.11,
" Technical Specifications Bases Control Program," to reflect the changes provided in Attachment 4. An affidavit supporting the facts set forth in this letter and its attachments is provided in Attachment 1.
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IP has reviewed the proposed changes against the criteria of 10CFR51.22 for categorical exclusion from environmental impact considerations. The proposed changes do not involve a significant hazards consideration, or significantly increase individual or
] , ,' l ' . Ob 9502150242 950210 }
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. . I U-602406 Page 2 cumulative occupational radiation exposures. Based on the foregoing, IP concludes that ,
the proposed changes meet the criteria given in 10CFR51.22(c)(9) for a categorical exclusion from the requirement for an Environmental Impact Statement.
Sincerely yours,
/ " V
. G. C k Vice President DAS/csm Attachments cc: NRC Clinton Licensing Project Manager NRC Resident Office, V-690 Regional Administrator, Region III, USNRC Illinois Department ofNuclear Safety i
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Attachment 1 to U-602406 !
l J. G. Cook, being first duly sworn, deposes and says: That he is Vice President ofIllinois Power; that the application for amendment of Facility Operating License NPF-62 has been prepared under his supervision and direction; that he knows the contents thereof; and that to the best of his knowledge and belief said letter and the facts contained therein are true and correct.
A Date: This /0 ' day of February 1995.
Signed: ;
h J. G. Cook STATE OF ILLINOIS l SS. '0FFICIAL SEAL' amennes.umses I NaryPwes,ansd amh
)< vlin COUNTY J ;; MyCommissionEspiros1WMSF ,
":::::::==::::: :::::::
Subscribed and sworn to before me this lo# day of February 1995.
armm ed '/ Nrm e
/ otary Joblic) /
Attachm:nt 2 to U-602406 LS-95-001 Page1 of5 l
Ilackground Clinton Power Station (CPS) Technical Specification (TS) 3.3.2.1, " Control Rod Block i Instrumentation," specifies the requirements for the Control Rod Block Instrumentation, !
including testing requirements. The requirements of the current CPS TS were patterned l after NUREG-1434, " Standard Technical Specifications, General Electric Plants, BWR/6," ,
Revision 0, dated September 1992. As stated in the Bases for this TS, the purpose of the controls enforced by the control rod block instrumentation is to ensure that fuel design limits are not exceeded for postulated transients and accidents. These Bases funher state
- that during high power operation, the rod withdrawal limiter (RWL) provides protection
! for control rod withdrawal error events.
The purpose of the RWL is to limit control rod withdrawal to preclude violation of the Minimum Critical Power Ratio (MCPR) Safety Limit and the cladding 1% plastic strain fuel design limit that could result from a single control rod withdrawal error (RWE) event.
As described in CPS Updated Safety Analysis Report (USAR) Sections 15.4.1 and 15.4.2, a statistical analysis of RWE events was performed to determine the MCPR response as a function of withdraw:d distance and initial operating conditions. Based on the RWE analyses, no limitations are required on continuous control rod withdrawal below 35%
Rated Thermal Power (RTP). That is, below 35% RTP, the consequences of a RWE event will not cause MCPR limits to be exceeded. At power levels of 35% RTP and greater, continuous control rod withdrawal must be limited to two-foot increments.
Further, at power levels of 70% RTP and greater, continuous control rod withdrawal must be further limited to one-foot increments.
Consistent with the above-noted RWE analyses, the RWL low power setpoint (LPSP) is established below 35% RTP to automatically enforce the two-foot (four-notch) continuous control rod withdrawal limitations of the RWL. Similarly, the RWL high power setpoint (HPSP) is established below 70% RTP to automatically enforce the one-foot (two-notch) continuous control rod withdrawal limitations of the RWL. These requirements are currently identified in TS Table 3.3.2.1-1, " Control Rod Block Instrumentation," and associated footnotes (b) and (a), respectively. As described in USAR Section 7.6.1.7, below the LPSP, the RWL is automatically bypassed; above the LPSP but below the HPSP, continuous control rod withdrawals are limited to four notches (two feet); and above the HPSP, continuous control rod withdrawals are limited to two notches (one foot).
Reactor power level input to the RWL is determined by measuring the main turbine first stage pressure. The RWL LPSP and the RWL HPSP are based on actual plant data taken at various power levels during plant startup. The RWL LPSP was established to provide a trip setpoint between 20% RTP and 35% RTP accounting for instrument uncertainties, drift, and affects of reduced feedwater heating. The RWL HPSP was established to provide a trip setpoint below 70% RTP accounting for instrument uncertainties, drift, and
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Attachment 2 to U-602406 LS-95-001 Page 2 of 5 affects of reduced feedwater heating. As a result of the above-noted effects on the first stage turbine pressure instruments, the actual setpoint for the RWL HPSP is somewhat less than the analytical limit of 70% RTP.
As stated above, the TS requirements contained in the CPS TS were based on NUREG-1434. The surveillance requirements for the RWL when operating above 70% RTP (which is the analytical limit for the two-notch RWL limitation) include a CHANNEL FUNCTIONAL TEST (CFT) of the RWL two-notch operating mode per Suncillance Requirement (SR) 3.3.2.1.1. As stated above, this mode of the RWL is automatically placed into effect when operating above the HPSP. The surveillance requirements for the RWL when operating at or belqw 70% RTP and greater than 35% RTP (which are the analytical limits for the four-notch RWL limitation) include a CFT of the RWL four-notch operating mode per SR 3.3.2.1.2. As stated above, this mode of the RWL is automatically placed into effect when opert, ting between the LPSP and the HPSP.
SR 3.3.2.1.1 and SR 3.3.2.1.2 currently contain Notes which allow one hour to perform these CFT SRs after the specified conditions are met. As stated in the Bases, the purpose of these Notes is to allow entry into the plant conditions necessary to perform the test. As stated above, the LPSP and HPSP are conservatively set to allow for instmmentation uncertainties, drift, and the effects of reduced feedwater heating. As a result, a significant margin can exist between the actual LPSP and HPSP and their associated analytical limits. j In fact, the HPSP at CPS is on the order of 52% RTP (as compared to 70% RTP). This creates two situations that need to be corrected due to the fact that a difference exists between when the SR.s become applicable and when the SRs can actually be performed.
First, during reactor startups, as reactor power is increased above the HPSP but remains below 70% RTP, the RWL automatically switches from the four-notch RWL mode to the two-notch RWL mode. While this provides conservative restrictions on the continuous withdrawal of control rods (withdrawal is restricted to two-notches rather than the required four-notches), as long as power remains below 70% RTP the TS do not currently require OPERABILITY or CFT testing of the two-notch RWL mode. Thus, reliance is being placed on equipment that is technically not required to be OPERABLE by TS.
Second, during power reductions, as reactor power is decreased below 70% RTP but i remains above the HPSP, OPERABILITY and CFT testing of the four-notch RWL mode is required by Table 3.3.2.1-1 and SR 3.3.2.1.2. However, because reactor power is still greater than the HPSP, the RWL operates in the two-notch mode. Again, RWL operation is consenative in this instance (since continuous control rod withdrawal would be limited to two-notches rather than the required four-notches), however, as long as power remains below 70% RTP the TS do not currently regt. ire OPERABILITY or CFT testing of the two-notch RWL mode. Again, reliance is placed on equipment which is technically not required to be OPERABLE by TS. In addition, the current note to SR 3.3.2.1.2 allows
Attachment 2 to U-602406 LS-95-001 Page 3 of 5 one hour after reducing power below 70% RTP to perform testing of the four-notch RWL mode. However, this testing cannot physically be performed until power is reduced below the HPSP. With the current setting of the HPSP and the normal rate at which power is typically reduced for a plant shutdown, power cannot be reduced below the HPSP within the one hour allowed. This is not consistent with the Bases for this note (which is to provide a reasonable time period to perform the required surveillance under appropriate plant conditions). Further, if the power reduction was only temporary and reactor power could not be restored to greater than 70% RTP without the withdrawal of control rods, reactor power would first have to be further reduced to below the HPSP in on der to perform a CFT on the four notch RWL mode prior to control rods being allowed to be withdrawn. (This situation would be created as a result of having to declare the four-notch RWL mode inoperable due to SR 3.3.2.1.2 not being met which would further result in entry into Condition A. Condition A requires control rod withdrawal to be suspended). Thus, as written, the Note to SR 3.3.2.1.2 has the potential to result in unnecessary loss of power production.
Because there is no overlap in the requirements below the LPSP, similar concerns do not exist for noeration near the LPSP.
Description of Proposed Chances l l
In accordance with 10CFR50.90, the following changes to TS 3.3.2.1 are being proposed:
(1) The note associated with SR 3.3.2.1.1 has been revised to replace "> 70% RTP" j with " greater than the RWL HPSP."
(2) The note associated with SR 3.3.2.1.2 has been revised to replace "5 70% RTP" with "less than or equal to the HPSP "
(3) Table 3.3.2.1-1 footnote (a) has been revised to replace "> 70% RTP" with l
" greater than the RWL HPSP." In addition, footnote (b) has been revised to l replace "5 70% RTP" with "less than or equal to the RWL HPSP." l The proposed changes to the CPS TS are reflected in Attachment 3. In addition, changes to the CPS TS Bases to clarify the requirements associated with this request are provided in Attachment 4.
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Attachment 2 to U-602406 LS-95-001 Page 4 of 5 Justification for Proposed Changes In order to resolve the first problem described above, Trlme 3.3.2.1-1 footnote (b) has been modified to require operability and testing of the four-notch RWL mode only when operating at power levels greater than 35% RTP and less than or equal to the RWL HPSP
[per change (3) described above]. In addition, Table 3.3.2.1-1 footnote (a) has been modified to require operability and testing of the two-notch RWL mode only when operating at power levels greater than the RWL HPSP [per change (3) described above].
Thus, when operating above the HPSP but below 70% RTP during a power increase, for example, SR 3.3.2.1.1 (CFT for the two-notch RWL mode) would now appropriately be required to be met [per the change to footnote (a) per change (3) described above), the revision to the note to SR 3.3.2.1.1 would allow one hour to perform the SR ifit has not been performed within the last 92 days [per the change (1) described above], and SR 3.3.2.1.2 (for testing the four-notch RWL mode) would not be required to be met [per the change to footnote (b) per change (3) described above).
In order to resolve the second problem, the note for SR 3.3 2.1.2 (CFT for the RWL four-notch mode) has been revised [per change (2) described above] to allow one hour to perform the SR afler power is less than the HPSP, rather than 70% RTP. Thus, when reducing power below 70% RTP but when power remains greater than the HPSP, SR 3.3.2.1.1 (two-notch RWL mode) would continue to be met (just as it was when operating with power greater than 70% RTP) and performance of SR 3.3.2.1.2 (four-notch RWL mode) would not be required until power is reduced below the HPSP [per the change to footnote (b) per change (3) described above). This will conservatively ensure that continuous control rod withdrawals are limited to two notches in this power range by equipment required to be OPERABLE by TS. When operating below the HPSP but above 35% RTP (during a power reduction), SR 3.3.2.1.1 (two-notch RWL mode) would not be required to be met [per the change to footnote (a)], and SR 3.3.2.1.2 (four-notch RWL mode) would continue to be required to be met, but the revision to the note to SR 3.3.2.1.2 [per change (2) described above] would allow one hour to perform the SR ifit has not been performed within the last 92 days.
It should be noted that the TS requirements for OPERABILITY and testing of the RWL prior to issuance of Amendment No. 95 (which approved the conversion of the CPS TS to the format of NUREG-1434) were based on the actual HPSP rather than the analytical limits. Per TS surveillance 4.1.4.2.b, the RWL was required to be tested "as each power range above the LPSP is entered during a power increase or decrease." Thus, testing was triggered solely based on the actual HPSP setting. The changes proposed in this request are consistent with the testing that was required prior to the issuance of Amendment No.
95 to the CPS TS.
Attichment 2 to U-6024% !
LS-95-001 :
Page 5 of 5 i Buis fpr No Sinnificant Hazards Consideration In accordance with 10CFR50.92, a proposed change to the Operating License (Technical l Specifications) involves no significant hazards considerations if operation of the facility in i accordance with the proposed change would not: (1) involve a significant increase in the probability or consequences of any 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 changes are ;
evaluated against each of these criteria below: )
- 1) The proposed changes are consistent with the Rod Withdrawal Error (RWE) l analysis presented in Clinton Power Station (CPS) Updated Safety Analysis Report j (USAR) Section 15.4.2. The proposed changes do not result in any change to j plant equipment or operation; only the plant conditions for which the Rod :
Withdrawal Limiter (RWL) function (s) are required to be tested are being revised. ]
The proposed changes continue to ensure that the RWL is OPERABLE and tested :
to ensure that continuous control rod withdrawals remain within the assumptions !
of the RWE analyses. The proposed changes have no impact on the probability of !
occurrence of a RWE event. Therefore, the proposed changes do not result in a j significant increase in the probability or consequences of any accident previously !
evaluated. !
- 2) The proposed changes do not result in any changes to plant equipment or i operation; only the plant conditions for which the RWL function (s) are required to be OPERABLE and tested are being revised. The proposed changes continue to -
ensure that the RWL is OPERABLE and tested to ensure that continuous control rod withdrawals remain within the assumptions of the RWE analyses. As a result, l no new failure modes are introduced. The proposed changes are clearly within the l limits of plant operation as described in the USAR and the RWE analyses. i Therefore, the proposed changes cannot create the possibility of a new or different ,
kind of accident from any accident previously evaluated. ,
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- 3) The proposed changes revise the testing requirements to be consistent with the ;
testing required prior to Amendment No. 95. The proposed changes ensure that the RWL is OPERABLE and tested to ensure that continuous control rod !
withdrawals remain within the assumptions of the RWE analysis. The proposed changes are clearly within the limits of plant operation as described in the USAR !
and the RWE analyses. Therefore, the proposed changes do not involve a i reduction in a margin of safety. !
i Based upon the foregoing, Illinois Power has concluded that these proposed changes do not involve a significant hazards consideration.
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