ML20206J712
| ML20206J712 | |
| Person / Time | |
|---|---|
| Site: | Vermont Yankee  |
| Issue date: | 05/05/1999 |
| From: | Wanczyk R VERMONT YANKEE NUCLEAR POWER CORP. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| Shared Package | |
| ML20206J715 | List: |
| References | |
| BVY-99-69, NUDOCS 9905120310 | |
| Download: ML20206J712 (19) | |
Text
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VERMONT YANKEE (y '
NUCLEAR POWER CORPORATION a 185 Old Ferry Road, Brattleboro, VT 05301 7002 (802) 257 5271 May 5,1999 BVY 99-69 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555
References:
(a) Letter, VYNPC to USNRC, " Deferral of ATWS Rule (10CFR50.62) Technical Specifications," BVY 97-95, dated July 25,1997.
(b) Letter, USNRC to VYNPC, " Vermont Yankee Nuclear Power Station - Withdrawal of an Amendment Request (TAC No. M88768)," NVY 97-129, dated August 12, 1997.
Subject:
Vermont Yankee Nuclear Power Station License No. DPR-28 (Docket No. 50-271)
Technical Specification Proposed Change No. 212 4
ATWS Rule (10CFR50.621-Standby Llauld Control System Pursuant to 10CFR50.90, Vermont Yankee (VY) hereby proposes to amend its Facility Operating License, DPR-28, by incorporating the attached proposed change into the VY Technical Specifications.
This proposed change modifies the Technical Specifications to enhance limiting conditions for operation and surveillance requirements relating to the Standby Liquid Control (SLC) system and incorporates certain provisions of NRC's rule on anticipated transients without scram (ATWS)(10CFR50.62). The change involves the use of enriched boron in the SLC system and improves upon other aspects of the Technical Specifications for this system.
In Reference (a) VY withdrew a similar proposed change and committed to incorporate any necessary ATWS rule Technical Specifications changes in Improved Technical Specifications (ITS). By Reference (b), the NRC subsequently granted VY's request for withdrawal. Due to changed circumstances, VY has delayed implementation ofITS as a result of other priorities. Because of this delay, VY has elected to make the submittal of this proposed change at this time, i
Attachment I to this letter contains supporting information and the safety assessment of the proposed i i
change. Attachment 2 contains the determination of no significant hazards consideration. Attachment 3 provides a marked-up version of the current Technical Specification pages with the changes noted.
Attachment 4 is the retyped Technical Specification pages incorporating the changes.
VY has reviewed the proposed Technical Specification change in accordance with 10CFR50.92 and- I concludes that the proposed change does not involve a significant hazards consideration. g 9905120310 990505 l ADOCK 05000271 i
)
l VEtotoNT YAshi.E Nrci.EAH PowEn Com>on mon BVY 99-69 / Page 2 VY has also determined that the proposed change satisfies the criteria for a categorical exclusion in .
accordance with 10CFR51.22(c)(9) and does not require an environmental review. Therefore, pursuant to 10CFR51.22(b), no environmental impact statement or environmental assessment needs to be prepared j for this change. j If you have any questions on this transmittal, please contact Mr. Thomas B. Silko at (802) 258-4146. I 1
Sincerely, VERMONT YANKEE NUCLEAR POWER CORPORATION Robert J. W cz'k ggf Director o S ty and Regulatory Aff '_
q h V OAI/O[h,p STATE OF VERMONT )
)S8 g '
NOTAR) ,
WINDilAM COUNTY ) g I
4 PUBUC Then personally appeared before me, Robert J. Wanczyk, who, being duly sworn, stat at he is rec Safety and Regulatory Affairs of Vermont Yankee Nuclear Power Corporation, that $ ily a to ee and file the foregoing document in the name and on the behalf of Vermont Yankee Nu rCogo d that the statements therein are true to the best of his knowledge and belief. yNIT'
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Sally A. Sandstrum, Notary Public My Commission Expires February 10,2003 Attachments cc: USNRC Region 1 Administrator USNRC Resident inspector - VYNPS USNRC Project Manager- VYNPS Vermont Department of Public Service 1
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.p 8 Vnum>NTYANstitNecu Asi POWl'.H COHl'ORAllON
, . Docket No. 50-221 BVY 99-69 Attachment 1
-]j Vermont Yankee Nuclear Power Station l b
Proposed Technical Specification Change No. 212 ATWS Rule (10CFR50.62)- Standby Liquid Control System Supporting Information and Safety Assessment of Proposed Change 1
'i .
a VEHMoNT YANKlit: Nt'cix.Au l'oWi n CouronxtioN BVY 99-69 / Attachment I / Page 1 INTRODUCTION NRC promulgated 10CFR50.62 " Requirements for Reduction of_ Risk from ' Anticipated Transients Without Scram (ATWS) Events for Light Water-Cooled Nuclear Power Plants" (known as the ATWS j rule) to require specific improvements in the design and operation of nuclear power plants to reduce the J likelihood of failure to shut down the reactor following anticipated transients, and to mitigate the I consequences of an ATWS event. Paragraphs (cX3), (cX4), and (cX5) of 10CFR50.62 establish {
functional requirements for three boiling water reactor (BWR) systems: alternate rod injection, standby l
~I liquid control, and recirculation pump trip, respectively. Vermont Yankee (VY) fully complies with -
these requirements and has previously provided NRC with information in this regard.
In Reference (a) NRC requested that VY propose Technical Specifications associated with ATWS-related components. VY had proposed a license change pertaining to one of the BWR systems, .which NRC granted by Reference (b) as Amendment 58, which incorporated provisions for an ATWS recirculation pump trip (RPT) into the Technical Specifications. The current Technical Specifications are therefore adequate in addressing the ATWS rule requirements for RPT. j Alternate rod injection does not meet the criteria of 10CFR50.36(cX2Xii); consequently, no Technical Specifications have been developed for this system. This submittal deals exclusively with the remaining ATWS system-standby liquid control.
As NRC developed guidance and clarification regarding implementation of the ATWS rule, VY made several submittals to the NRC, including proposed Technical Specifications. Culminating these efforts, in 1997 VY proposed to incorporate any necessary ATWS rule Technical Specifications changes in Improved Technical Specifications (ITS) and by Reference (c) withdrew a proposed change to Technical Specifications similar to this submittal. By Reference (d), the NRC subsequently granted VY's request for withdrawal. Due to changed circumstances, VY has delayed implementation of ITS as a result of other priorities and has elected to make the submittal of this proposed change at this time.
In addition to incorporating requirements of the ATWS rule, other enhancements to Technical Specifications are being made with this submittal and are discussed in detail in this Attachment.
SAFETY ASSESSMENT System Description and Design Bases:
VY's standby liquid control (SLC) system provides backup capability for reactivity control as described in FSAR section 3.8.2. De SLC system provides the capability to shut down the reactor from full power by the injection of a borated water solution into the reactor pressure vessel. The system is needed!
the improbable event that control rods cannot be inserted sufficiently to accomplish shutdown in the normal manner.
~he design basis for the SLC system is to provide a soluble boron concentration te the reactor vessel sufficient to bring the reactor to a cold shutdown condition. The specified minimum average concentration of natural boron in the VY reactor to assure shutdown, after operation of the standby liquid control system, is less than 800 ppm (mg/kg). The minimum quantity of sodium pentaborate to be injected into the reactor is calculated based on the 800 ppm average concentration in the reacto and the quantity of reactor coolant in the reactor vessel and recirculation loops. The amount calcu Note: A listing of references discussed in this section is found at the end of this Attachment.
VruuoN Ymtr Nrcian Powrn Couronrriox -
BVY 99-69 / Attcchment I / Page 2 increased by 25% to allow for imperfect mixing, leakage, and volume in other small piping connected to the reactor. ,
The SLC system is capable of delivering a minimum of 3,850 gallons of 10.1% sodium pentaborate decahydrate solution (Na2B10016 : 1011 20) or equivalent into the reactor. The system includes parallel active components to ensure high reliability. Operationally, the sodium pentaborate solution is maintained above its saturation temperature to ensure that precipitation does not occur.
ATWS Rule:
The ATWS rule added specific SLC system reactivity control requirements. The basic requirement for the standby liquid control system is specified in paragraph (c)(4) of 10CFR50.62 which states, in part:
Each boiling water reactor msat have a standby liquid control system (SLCS) with the capability ofinjecting into the reactor pressure vessel a borated water solution at such aflow rate, level of boron concentration and boron 10 enrichment, and accounting for reactor pressure vessel volume, that the resulting reactivity control is at least equivalent to 86 gallons per minute of13 weightpercent sodiumpentaborate decahydrate solution at the natural boron.
10 isotope abundance into a 251 inch inside diameter reactor pressure vesselfor a given core design.
In brief, the rule requires the equivalent shutdown capability ofinjecting 13 weight percent natural boron ^
at 86 gpm into a 251-inch vessel. The NRC staff provided clarification on how the equivalency of reactivity control was to be accomplished in Reference (e).
This requirement effectively increased the rate of delivery into the reactor pressure vessel of the neutron I absorber (i.e., boron-10), Reference (f) provides three acceptable methods for complying with the requirement of 10CFR50.62(c)(4). The three methods are: (1) two-pump system operation; (2) increase the sodium pentaborate solution concentration; and (3) increase the boron-10 enrichment of the sodium pentaborate solution. VY chose to implement the third alternative (i.e., enriched boron) because it offered several advantages, including the ability to maintain system redundancy and did not require system hardware modifications.
With boron enriched in the B-10 isotope in the sodium pentaborate solution, VY was able to meet the equivalent control capacity requirement of the rule. This design alternative maintains one-pump operation and the existing solution concentration. Accordingly, the equivalent control capacity requirement was met for the 205-inch Vermont Yankee reactor vessel by appropriately enriching the borated water solution. I The equivalency requirement of the ATWS rule can be demonstrated if the following relationship is satisfied:
Q 86 X
- M251 M
XC 13 X
E 19.8 2: 1 where: Q = rate of injection of sodium pentaborate solution (gpm; 86 gpm is the injection rate ,
specified in the ATWS rule for the reference plant.)
l
l
= .
l
.VIMolONT YANKle.E Nt'CilAM l'HWl:H Cont *ORNELON {
BVY 99 69 / Attachment I / Page 3 M = mass of water in the Vermont Yankee reactor vessel and recirculation system at hot <
- - rated conditions (401,247 lbm) :
M251 = M for the 251-inch reference plant reactor vessel (628,300 lbm)
C = sodium pentaborate solution concentration (weight percent; 13 weight percent is the concentration specified in the ATWS rule for the reference plant.)
E = boron-10 isotope enrichment (atom percent; 19.8% for natural boron)
The calculations to support injection flow rates and the design values for the concentrations and !
enrichments were performed by VY to determine the VY SLC system configuration needed to meet the equivalent control capacity. The equivalency bases take into account the specific plant values of water mass in the reactor, SLC flow rate, sodium pentaborate concentration and boron-10 enrichment.
Implementation of the above relationship provides the basis for the proposed Technical Specifications change which is described in further detail in the following table. Other specific aspects of the current Technical Specifications related to the SLC system are also being enhanced and are also described in the following table.
j VY meets the requirements of 10CFR50.62(c)(4) and conforms to the approved design alternative noted in Section 5.2.3 of NRC's safety evaluation of GE Topical Report NEDE-31096-P-A provided to the l Boiling Water Reactor Owners Group by Reference (g).
VamoNT YAmt NecaxMt Powat CoswoitutoN IWY 99-69 / Attachment I / Page 4 DESCRIPTION AND BASES FOR EACH CHANGE:
Ite m Description and Bases
[1] Replace current Technical Specification 3.4.A with the following:
Section 3.4.A.
Page 92 A. Normal Operation Except as specified in 3.4.B below, the Standby Liquid Control System )
shall be operable when the reactor mode switch is in either the "Startup/ Hot Standby" or "Run" position, except to allow testing of I
Instrumentation associated with the reactor mode switch interlock functions provided:
- 1. Reactor coolant temperature is less than or equal to 212* F;
- 2. All control rods remain fullyInsertedin core cells containing one or more fuel assemblies; and 1
- 3. No core alterations are in progress.
Current Technical Specification 3.4.A requires that the Standby Liquid Control i System (SLCS) be operable except as specified in Specification 3.4.B, and when fuel is in the reactor, unless: (1) the reactor is in cold shutdown, and (2) control rods are fully inserted and Specification 3.3.A (Reactivity Limitations) is met.
The exception, "as specified in 3.4.8 below," is retained and unchanged from current Technical Specifications.
New Specification 3.4.A. provides that the Standby Liquid Control System need not be operable when the reactor mode switch is in either Refuel or Shutdown.
During refueling, this change provides for control rod and/or control rod drive maintenance while the SLCS is inoperable.
Current Specification 3.3.A requires certain shutdown margin be provided any time there is fuel in the core. Since Specification 3.3.A is still required, it is unnecessary and redundant to include this Specification in 3.4.A. With the-required shutdown margin not met with the reactor mode switch in the " Refuel" position, current Specification 3.3.A.1 already specifies remedial actions to-assure safety. Du ing refueling with the reactor cavity flooded the SLC system borated solution,11 injected into the reactor vessel, would be diluted beyond design basis concentrations of boron in the reactor vessel. Shutdown and refueling present such conditions that are beyond the design basis of this system.
With the reactor mode switch in the " refuel" position, only a single control rod . ,
can be withdrawn from a core cell containing fuel assemblies.- Determination of adequate shutdown margin ensures that the reactor will not become critical with one control rod withdrawn. Current Specification 4.3.A.1 calls for verification
1 Vr.mioNT VA.wim Ni ciran Pows:n CouronATioN BVY 99-69 / Attachment I / Page 5 i t
[1] that the required shutdown margin is met prior to each in-vessel fuel movement (continued) during the fuel loading sequence. In addition, current Technical Specification 3.12.D addresses shutdown margin requirements during control rod and control _j rod drive rnaintenance. These features and requirements further demonstrate l !
that the SLCS need not be operable during refueling when only a single control rod can be withdrawn.
New Specification 3.4.A. retains the exception that SLCS need not be operable when the reactor is in a cold shutdown condition.
With the reactor mode switch in the " shutdown" position, all rods are automatically inserted and control rods cannot be withdrawn since a control rod withdrawal block is applied. This provides adequate controls to ensure that the reactor is and remains suberitical. With the reactor in a cold shutdown condition and reactivity margins established, the SLCS is not needed as a backup system to shut down the reactor assuming failure of control rods to insert, since sufficient control rods are already inserted. Consequently, under these conditions SLCS may be inoperable.
Revised Technical Specification 3.4.A. provides the same degree of safety as is contained in current Technical Specification 3.4.A. With the mode switch in shutdown, control rods cannot be withdrawn.
The Standby Liquid Control System need not be operable when the reactor is shut down by the control rod drive system and is subcritical with the proper shutdown margin. With the reactor mode switch in shutdown, control rods are not able to be withdrawn since a control rod block is applied. This provides 1 adequate controls to ensure that the reactor remains subcritical, j j
Revised Technical Specification 3.4.A also allows reactor mode switch interlock testing to be conducted by placing the mode switch in "Run" or "Startup/ Hot Standby" under strict conditions with the Standby Liquid Control System inoperable. The reactor mode switch has four positions: (1) Run; (2) ;
1 Startup/ Hot Standby; (3) Shutdown; and (4) Refuel. Current Technical Specifications require that the Standby Liquid Control System be operable in all but one mode switch position (i.e., Shutdown), and then only with certain additional restrictions. The current Technical Specificatio13.4.A is overly restrictive in this regard in that the design basis for the Standby Liquid Control System specifies that there is no requirement for operability of the system when )
the reactor is shutdown by the control rod system and suberitical with the i proper shutdown margin.
Interlock testing that requires moving the reactor mode switch to other positions (i.e., "Run" or "Startup/ Hot Standby") while the reactor is shuMown or refueling, requires administratively maintaining all control rods inserted and no core alterations in progress. With all control rods inserted in core cells containing one or more fuel assemblies, and no core alterations in progress, there are no-credible mechanisms for unacceptable' reactivity excursions during the planned interlock testing.
VEumm hnEE NrCEEAR PowEn CoHPonAnoN BVY 99-69 / Attachment I / Page 6 (1] Under the specified conditions of reactor coolant less than or equal to 212* F, (continued) all control rods remain fully inserted in core cells containing one or more fuel assemblies, and no core alterations in progress, the Standby Liquid Control System need not be operable since equivalent cold shutdown conditions are achieved, although the mode switch may not be in " Shutdown." The interlock testing can only proceed if all of the stated conditions are met. Control rods are not required to be inserted in empty core cells (i.e., those containing no fuel) because, with one or more core cells in this configuration, the shutdown margin is actually greater than when all control rods and all fuel assemblies are inserted. This is recognized in current Technical Specification 3.12.E, which allows control rod removal if all fuel assemblies in the control cell are removed.
This is a less restrictive change in that the Standby Liquid Control System is no longer required to be operable for the operational modes previously specified.
[2] in the fourth line of current Technical Specification 4.4.A.1, change " Minimum" Section 4.4.A.1 to " minimum." This corrects a typographical error and as such represents an Page 92 administrative change. l (3) In the last sentence of current Technical Specification 4.4.A.1, delete the ending Section 4.4.A.1 phrase: ." .by recirculating demineralized water to the test tank."
i Page 92 Details / requirements to verify system flow by recirculating demineralized water to the test tank are not necessary in the Technical Specifications to ensure that the SLC system is maintained operable. The requirements of current Technical Specifications 4.4.A.4 and Specification 4.6.E are adequate to ensure the capability to provide flow through each SLC subsystem into the reactor pressure vessel. The phrase,"by recirculating demineralized water to the test tank" is being relocated to Bases section 3.4.A & 4.4.A as a parenthetical expression in the second sentence of the current third paragraph.
The details being removed from Technical Specifications by this change will be relocated to the Bases section of the Vermont Yankee Nuclear Power Station Technical Specifications. The relocation of these details to the Bases is acceptable considering the controls provided by the remaining Technical Specifications and the Bases change control process. Changes to the Technical Specifications Bases are controlled by the provisions of 10CFR50.59.
[4] In the first sentence of current Technical Specification 4.4.A.4, delete the Swtion 4.4.A.4 phrase: "...by pumping demineralized water into the reactor vessel." As in item Page 93 [3] above, details / requirements to verify a flow path are not necessary in the Technical Specifications to ensure that the SLC system is maintained operable.
The requirements of current Technical Specifications 4.4.A.4 and Specification 4.6.E are adequate to ensure the capability to provide flow through each SLC subsystem into the reactor pressure vessel.
This phrase will be relocated to Bases section 3.4.A & 4.4.A by adding the following sentence at the end of the current third paragraph:
In addition, at least once during each operating cycle, one of the standby liquid controlloops will be Initiated to verify that a flow path from a pump
VEnMoNr YAmn Necuan PowEn CowonxnoN BVY 99-69 / Attachment 1/ Pige 7 I
(4) to the reactor vesselIs available by pumping domineralized waterinto the (continued) reactor vessel.
The details being removed from Technical Specifications by this change will be relocated to the Bases section of the Vermont Yankee Nuclear Power Station Technical Specifications. The relocation of these details to the Bases is acceptable considering the controls provided by the remaining Technical Specifications and the Bases change control process. Changes to the Technical Specifications Bases are controlled by the provisions of 10CFR50.59.
Change the heading title of current Technical Specifications 3/4.C from " Liquid !
[5]
Section 3/4.C Poison Tank - Boron Concentration" to " Standby Liquid Control System Tank -
Page 93 Borated Solution." ;
This change accomplishes two objectives: (1) It changes the tank nomenclature to reflect the name currently in use at VY (i.e., " Standby Liquid Control System Tank"); and (2) the title change is also necessary to more accurately reflect the Specifications which follow. As such, this change in ,
I nomenclature is editorial in nature and is preferred to prevent operator misunderstanding or confusion. Therefore, it is an administrative change since it does not modify any existing technical requirement (either actual or interpretational).
[6] insert the following as new Specification 3.4.C.3:
Section 3.4.C Page 94 3. The combination of Standby Liquid Control System pump flow rate, boron concentration, and boron enrichment l
shall satisfy the following relationship for the Standby Liquid Control System to be considered operable:
Q M251 C E x x x 2 1 86 M 13 19.8 where: C = the concentration of sodium pentaborate solution (weight percent) In the Standby Liquid Control System tank E = the boron-10 enrichment (atom percent) of the sodium pentaborate solution Q = 35 gpm M251 = a constant (the ratio of mass of waterin the '
M reference plant compared to W)
New Specification 3.4.C.3 establishes a relationship among SLCS flow, concentration and boron enrichment in accordance with the ATWS Rule. (See the discussion which precedes this table.) As such, this is a new Tech'nical Specification requirement which conforms to 10CFR50.62(c)(4) and is in
ViiHMONT Yassiis; Nt cirAH l'Ows:H COHl'OHAllON BVY 99-69 / Attachment I / Page 8
[6] keeping with the regulation. This stricter operating limitation does not negate (cdntinued) any other requirement and does not adversely affect other safety design bases.
To satisfy this equation, VY utilizes boron at the appropriate concentration, boron-10 enrichment and a pump flow rate of at least 35 gpm. The established pump flow rate (i.e.,35 gpm) is the minimum allowable per Specification 4.4.A.1. Implementation of the enriched boron option for compliance with the ATWS Rule was previously found acceptable by NRC as one of the alternatives for meeting 10CFR50.62(c)(4). Therefore, this new restriction has already been reviewed and found acceptable by the NRC staff.
[7] Insert the following as new Specification 4.4,C.3:
Section 4.4.C Page 94 3. The boron-10 enrichment of the borated solution required by SpeclHcation 3.4.C.3 shall be tested and verified once per operating cycle.
i New Specification 4.4.C.3 requires periodic testing and verification of the enrichment of the boron-10 isotope in the sodium pentaborate solution. Isotopic testing to verify the actual boron-10 enrichment ensures that borated solution is properly maintained and that new Specification 3.4.C.3 is met. As such, this is an additional surveillance requirement which constitutes a more restrictive change.
[8] Insert the word, " Standby" before " Liquid Control System" in the second 83/4.4.A sentence of the first paragraph of current Bases 3.4 & 4.4 Section A. This Page 97 sentence will now read, "To meet this objective, the Standby Liquid Control System..."
This corrects an error in that the Standby Liquid Control system was incorrectly named.
[9] Insert the word " natural" in three places in the first paragraph of current Bases B3/4.4.A 3.4 & 4.4 Section A: (1) in the second sentence in the phrase, ".. 800 ppm of Page 97 boron..." to now read ".. 800 ppm of natural boron..."; (2) in the third sentence in the phrase, "An 800 ppm boron concentration..." to now read "An 800 ppm natural boron concentration..." and (3) in the last sentence in the phrase "...a 10.1% sodium pentaborate concentration..." to now read "...a 10.1% natural sodium pentaborate concentration..."
This change adds specificity to avoid confusion regarding the enrichment of the boron in solution based on the original design basis of the SLC system. Since enriched boron is now in use, it is necessary to clarify this statement which pertains to the original design basis. Prior to the ATWS rule being implemented, this was not a concern since only natural sodium pentaborate solution was used in the SLC system and that was the basis for this statement.
However, now that enriched boron is being used, this statement is being clarified to avoid potential misunderstanding.
Vr.nuoN1 YAum Nrci.r.An Powr.n Conron. mon BVY 99-69 / Attachment I / Page 9
[10] insert the following two paragraphs after the first two paragraphs of current l
'83/4.4:A Bases Section 3.4.A & 4.4.A:
Page 97 In addition to its original design basis, the Standby Liquid Control System also satisfies the requirements of 10CFR50.62(c)(4) on anticipated transients without scram (ATWS) by using enriched boron. The ATWS rule adds hot shutdown and neutron absorber (i.e., boron.10) Irdection rate requirements that exceed the original Standby Liquid Control System design basis. However, changes to the Standby Liquid Control System as a result of the ATWS rule have not invalidated the original design basis.
With the reactor mode switch in the "Run" or "Startup/ Hot Standby" position, shutdown capability is required. With the mode switch in
" Shutdown," control rods are not able to be withdrawn since a control rod block is appIled. This provides adequate controls to ensure that the reactor remains subcritical. With the mode switch in " Refuel," only a single control rod can be withdrawn from a core cell containing fuel assemblies. Determination of adequate shutdown margin by Specification 3.3.A ensures that the reactor will not become critical.
Therefore, the Standby Liquid Control System is not required to be operable when only a single control rod can be withdrawn.
The first paragraph inserted provides reference to the AN/S rule and how Vermont Yankee complies (i.e., by using enriched boron). This paragraph also provides distinction between the original design basis of the Standby Liquid Control System and the additional requirements due to the ATWS rule.
The second paragraph inserted provides the basis for revised Specification 3.4.A (see item (1) above).
[11] Mos + the first sentence of the third paragraph of current Bases 3.4 & 4.4 B3/4.4.A Section A to the end of the last paragraph of current Bases 3.4 & 4.4 Section C Page 97 and change the word "by" in this sentence to "be." The word change corrects a typographical error.
Moving this sentence to Bases 3.4 & 4.4 Section C ' places it in the proper section of the Bases since Specification 4.4.C deals with the surveillance of boron concentration, solution temperature, and volume.
[12] Change the heading title of current Bases 3.4 & 4.4 Section C from " Liquid 83/4.4.C Poison Tank - Boron Concentration" to " Standby Liquid Control System Tank -
Page 97 Borated Solution" as was done in item (5) above. This is an administrative change.
[13] In the third sentence of the first paragraph of current Bases 3.4 & 4.4 Section C, B3/4.4.C change "... Figure 3.8.3 of the FSAR." to "... Figure 3.4.2."
Page 97 Figure 3.8.3 of the FSAR and Figure 3.4.2 of the Technical Specifications are technically identical.~ lt is more conducive for users of Technical Specifications
Vrnmm Ymtr Necuan Powrn Conmn.u n N BVY 99-69 / Attachment I / Page 10
[13] to refer to a Technical Specification figure, instead of an equivalent FSAR (continued) figure. This change reflects a preference and has no bearing on its use or application. Consequently, it is an administrative change.
[14] At the end of the last sentence at the very end of current Bases 3.4 & 4.4 B3/4.4.C Section C, add the word " personnel." The subject sentence will now read: "The i Page 98 24-hour limit allows for 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> of mixing, subsequent testing, and notification of shift personnel." This is an administrative change to clarify the statement.
[15] Insert the following sentence at the end of current Bases 3.4 & 4.4 Section C B3/4.4.C and after the sentence relocated by item [11] above:
Page 98 Isotopic tests of the sodium pentaborate are performedperiodically to ensure that the proper boron-10 stom percentage is being used.
This sentence provides the basis for the surveillance requirement of new Specification 4.4.C.3.
[16] Insert the following two paragraphs at the end of current Bases 3.4 & 4.4 B3/4.4.C Section C and after item [15] above:
Page 98 10CFR50.62(c)(4) requires a Standby Liquid Control System with a minimum flow capacity and boron content equivalent to 86 gpm of 13 welght percent natural sodium pentaborate solution in the 251-Inch reactor pressure vessel reference plant. Natural sodium pentaborate solution is 19.8 atom percent boron 10. The relationship expressed in Specification 3.4.C.3 also contains the ratlo M251/M to account for the difference in water volume between the reference plant and Vermont Yankee. (This ratio of masses is 628,300 lbs]401,247 lbs.)
To comply with the A7WS rule, the combination of three Standby Liquid Control System parameters must be considered: boron concentration, Standby Liquid Control System pump flow rate, and boron-10 enrichment.
Fixing the pump flow rate in Specification 3.4.C.3 at the minimum flow rate of 35 gpm conservatively estabilshes a system parameter that can be usedin satisfying the A1WS requirement, as well as the original system design basis. If the product of the expression in Specification 3.4.C.3 is equal to or greater than unity, the Standby Liquid Control System satisfies the requirements of 10CFR50.62(c)(4).
These two paragraphs explain the basis for new Specification 3.4.C.3 and the application of the ATWS rule.
Notes: Item numbers are identified in brackets [] on the marked-up pages which constitute Attachment 3.
Reference to Technical Specifications sections in this table refers to the current Technical Specifications, and not the revised Technical Specifications, unless specifically stated otherwise.
- BVY 99-69 / Anachment I / Page 11
REFERENCES:
(a) Letter, USNRC to VYNPC,"ATWS Rule (10 CFR 50.62): Plant Specific Reviews," NVY 87-04, dated January 8,1987.
(b)- Letter, USNRC to VYNPC, " Vermont Yankee License Amendment No. 58," dated November 3, 1980.
(c) Letter, VYNPC to USNRC, " Deferral of ATWS Rule (10CFR50.62) Technical Specifications,"
BVY 97-95, dated July 25,1997.
(d) Letter,.USNRC to VYNPC, " Vermont Yankee Nuclear Power Station - Withdrawal of an Amendment Request (TAC No. M88768)," NVY 97-129,' dated August 12,1997.
(e) USNRC Generic Letter 85-03," Clarification of Equivalent Control Capacity for Standby Liquid j Control Systems," NVY 85-15, dated January 28,1985.
(f) General Electric Licensing Topical Report, NEDE-31096-P-A, " Anticipated Transients Without Scram; Response to NRC ATWS Rule 10CFR50.62."
(g) Letter, USNRC to BWROG, " Acceptance for Referencing of Licensing Topical Report NEDE-31096-P, Anticipated Transients Without Scram; Response to NRC ATWS Rule,10 CFR 50.62," f dated October 21,1986.
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' VI',HMONT YANhlil' Nt'Ct.liAH l' Owl',lt Cong*ORxilON Docket No. 50-271 BVY 99-69 i
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Attachment 2 Vermont Yankee Nuclear Power Station Proposed Technical Specification Change No. 212 i
ATWS Rule (10CFR50.62)- Standby Liqbid Control System Determination of No Significant Hazards Consideration-i l
I (b$khb (O b!b be 4 kN k.fi.%H htWl;H (I()W()Mi%Il(W BVY 99-69 / Attechment 2 / Page 1 Pursuant to 10CFR50.92, VY has reviewed the proposed change and concludes that the change does not involve a significant hazards consideration since the proposed change satisfies the criteria in 10CFR50.92(c).
- 1. The coeration of Vermont Yankee Nuclear Power Station in accordance with the orooosed p_mendment. will not involve a significant increase in the orobability or consecuences of an accident oreviously evaluated.
The proposed change deletes the requirement for standby liquid control (SLC) system operability during refueling and modifies the conditions for allowing the system to be inoperable when shutdown.
This change also permits changing the reactor mode switch to the "Run" or "Startup/ Hot Standby" position to test mode switch interlock functions while the SLC system is inoperable. To allow testing of instrumentation associated with the reactor mode switch interlock functions, compensatory measures are provided for assuring that no core alterations are in progress and that all control rods remain fully inserted in core cells containing one or more fuel assemblies. These compensatory measures ensure that no credible mechanisms for an inadvertent criticality are introduced by administratively controlling the
. required functions of the reactor mode switch interlocks. Control rods are not required to be inserted in empty core cells (i.e., those containing no fuel) because, with one or more cells in this configuration, the overall shutdown margin is actually greater than when all control rods and all fuel assemblies are ~
inserted. ]
l The SLC system is not assumed in the initiation of any previously evaluated events and therefore the proposed change will not significantly increase the probability or consequences of a previously analyzed accident. The SLC system is not assumed to operate in the mitigation of any previously analyzed accidents which are assumed to occur during shutdown or refueling conditions. This change will not result in operation that will significantly increase the probability of initiating an analyzed event. This change will not alter assumptions relative to mitigation of an accident or alter the operation of process variables, structures, systems, or components as described in the final safety analysis report.
VY has determined that the proposed change to increase the standby liquid control system reactivity control capacity using a borated water solution enriched in the boron.10 isotope effectively increases the rate ofinjection of neutron absorber and does not alter the function of the system, method of operation or dual train configuration. The system response time to an anticipated transient without scram (ATWS) event has been reduced as the increased boron-10 enrichment of the solution provides faster negative reactivity insertion, thus reducing the consequences of the ATWS event. The SLC system is not credited in any of the design basis accident analyses and, as such, is considered to provide only an additional mitigative feature in the event of an accident. The SLC system sodium pentaborate solution concentration and flow rate required by the ATWS rule (10CFR50.62) for reactivity control independent of the control rods are not reduced from the values previously evaluated and presented in the Vermont Yankee Technical Specifications. He addition of enriched boron provides a shutdown margin greater than the previously calculated shutdown reactivity control capacity, and the change does not affect the probability of an ATWS event.
Therefore, this change will not involve a significant increase in the probability or consequences of an
. accident previously evaluated.
- 2. ' The operation of Vermont Yankee Nuclear Power Station in accordance with the proposed amendment. will not create the oossibility of a new or different kind of accident from any accident previously evaluated.
Vrnsu Nr YAmn NecmAn Powen ConronAmpN BVY 99-69 / Attachment 2 / Page 2 The propose'd change modines the modes of applicability for the SLC system. Included in this change is allowance to. permit changing the reactor mode switch to the "Run" or "Startup/ Hot Standby" position to test mode switch interlock functions while the SLC system is inoperable. Precautions are taken when manipult. ting the mode switch to one of these positions to maintain all control rods fully inserted in core cells containing at least one fuel assembly and to not allow any core alterations. These two provisions eliminate the possibility of introducing any credible mechanisms for inadvertent criticality. The proposed change will not involve a physical alteration of the plant (no new or different type of equipment will be installed) or changes in methods governing normal plant operation. The proposed change will not eliminate any valid requirements necessary for safe operation.
VY has determined that the proposed change does not create the possibility of a new or different kind of accident from any accident previously evaluated because the proposed change involves a system whose function is to provide an additional (backup) mitigative shutdown capability and no system modincations ']
are made. ]
1 The addition of enriched boron does not affect any system or component that could initiate an accident.
Thus, no new or different type of accident is created.
- 3. The operation of Vermont Yankee Nuclear Power Station in accordance with the proposed amendment will not involve a sinnincant reduction in a marain of safety.
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VY has determined that the proposed change does not involve a significant reduction in a margin of safety. The proposed change would remove the backup to the available reactivity control systems when the reactor is in a shutdown or refueling condition. However, this backup is not considered in the margin l of safety when determining the required reactivity for shutdown and refueling events. This change will have no impact on any safety analysis assumptions.
Included in this change is allowance to permit changing the reactor mode switch to the "Run" or "Startup/ Hot Standby" position to test mode switch interlock functions while the SLC system is inoperable. The margin of safety will not be reduced during such testing of interlock functions with the SLC system inoperable because compensatory measures have been added to ensure that no credible mechanisms for inadvertent criticality exist with the reactor mode switch in other than the " Shutdown" or " Refuel" positions.
The use of enriched boron in the SLC system sodium pentaborate solution actually increases the -
capability of the SLC system to achieve cold shutdown; thus, no margin of safety is reduced.
Conclusion On the basis of the above, VY has determined that operation of the facility in accordance with the proposed change does not involve a signincant hazards consideration as denned in 10CFR50.92(c), in that it: (1) does not involve a signi6 cant increase in the probability or consequences of an accident previously evaluated; (2) does not create the possibility of a new or different kind of accident from any accident previously evaluated; and (3) does not involve a significant reduction in a margin of safety.
Additionally, because the proposed amendment to the Vermont Yankee Technical Speci6 cations is directly associated with the ATWS rule (10CFR50.62), it is similar to Example (vii) provided by the NRC (SlFR7751, dated March 6,1986) as one of the types of amendments not likely to involve a.
signincant hazards consideration. Example (vii) denotes an amendment to make a license conform to chsges in the regulation when the license change results in very minor changes to facility operations
vnnsiost Y.mim Necuan Pownn Conronxinis BVY 99-69 / Attachment 2 / Page 3 clearly in keeping with the regulations. Additionally, aspects of the change proposed herein also resembles Example (ii), which denotes an amendment that constitutes an additional limitation, restriction or control not presently included in the Technical Specifications, in that stricter operating and surveillance requirements reflect additional conservatism. Additionally, portions of this change resemble Example (i), which denotes administrative changes to Technical Specifications since they seek to correct errors, change nomenclature, or achieve consistency throughout the Technical Specifications. Based on the above consideration of NRC examples of types of amendments not likely to involve a significant hazards consideration, Vermont Yankee has determined that the proposed amendment involves no significant hazards considerations.
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s 7 VEnMoNT YANKEit Nt'oi.i:An Powitu ConeonA1 oN l'
Docket No. 50-271 BVY 99 Attachment 3 Vermont Yankee Nuclear Power Station Proposed Technical Specification Change No. 212 ATWS Rule (10CFR50.62)- Standby Liquid Control System Marked-up Version of the Current Technical Specifications j
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