2CAN069107, Application for Amend to License NPF-6,proposing New Tech Spec Section 3/4.4.12 for low-temperature Overpressure Protection
| ML20081K925 | |
| Person / Time | |
|---|---|
| Site: | Arkansas Nuclear  |
| Issue date: | 06/18/1991 |
| From: | Carns N ENTERGY OPERATIONS, INC. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| Shared Package | |
| ML20081K928 | List: |
| References | |
| REF-GTECI-070, REF-GTECI-094, REF-GTECI-NI, TASK-070, TASK-094, TASK-70, TASK-94, TASK-OR 2CAN069107, 2CAN69107, GL-90-06, GL-90-6, TAC-77327, TAC-77399, NUDOCS 9107020167 | |
| Download: ML20081K925 (7) | |
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- Burn" Carna Vce Prescent Oswatons ANO June 18, 1991 2CAN069107 U. S. Nuclear Regulatory Commission Document Control Desk Hall Station PI-137 Washington, D. C. 20555 SUl1 JECT:
Arkansas Nuclear One - Unit 2 Docket Nos. 50-368 Licensa Nos. NPF-6 Low-Temperature Overpressurn Protection Technical Specification Change Request (TAC ltems 77327 and 77399)
Gentlemen Gennric Letter (Gh) 90-06 was issued on June 25, 1990 (OCNA069027), regarding resolution of Generic Issue 70 " Power-Operated Rnlief Valve and Block Valve Reliability'" and Generic issue 94, " Additional 1.ow-Temperaturn Overpressure Protection. Attachment A-1 to Enclosure A of the generic letters proposed modified Standard Technical Specifications on Combustion Engineering (CE) plants for power-operated relief valves (PORVs) in Modes 1, 2 and 3. 1-1 t o Enclosure B of the generic letter, likewlac, proposed modified Technical Specifications on CE plants for low-temperature overpressure protection (LTOP)
.in Hodos 4, 5 and 6.
Entergy Operations, at Arkansas Nuclear One (ANO), submitted our response to GL 90-06 for Unit 2, on December 21, 1990 (2CAN129013).
In our responan,.wn proposed to submit Technical Specifications to address thn PORVn and LTOP modified Standard Technical Specifications.
However, it was not ed that the ANO-2 design does not utilize PORVs for LTOP and that the proposed ANO-2 Technical Specifications could only utilize thn modified Standard Technical Specifications as guidance.
~is proposing a new ANO-2 Technical Specification Section Entergy Operations 3/4.4.12 for LTOP,'uti11xing the modified Standard Tnchnien1 Specificatione contained in the generic letter for the AND-2 LTOP relief valve design.
The proposed Technical Specification including surveillnnco rnquirements and 11ases
-are attached.
In addition. Technical Specification 6.9,2 is being changed to
-include a new reporting-requirement for reporting events involving mitigation of an LTOP pressure _t ransient.
As discussed herein, Technical Specifications for relief valves in Modes 1, -2 and 3 (as requestnd by Enclosure A of the gnneric letter) are not considered appropriate for ANO-2, since the ANO-2 LTOP design does not utilize the LTOP rnlief valves or their associated inoletion valves under these operating conditions.
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U.S. NRC June 18, 1991 Page 2 Additionally, due to a recent reanalysis of the ANO-2 pressure-temperature limits, Entergy Operations t hrough Combustion Engineering (CE) has recalculated the ANO-2 1. TOP related setpoints. These analyses and results are contained in Attachments 1 and 2 to the attached change request. is considered proprietary to CE and-1s, therefore, being submitted under a separate cover letter.
We request that the effective date for this change be 30 days after NRC issuance of the amendment to allow for distribution and procedural revisions necessary to implement this change.
e Please note that Entergy Operations is proposing further changes to these affected pages under a separate Technical Specification Change Request (OCANd69101).
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ps, err e NSC dr Attachments cci Mr. Robert Martin U. S. Nuclear Regulatory Commission Region IV 611 Ryan Plar.a Drive, Suite 1000 Arlington, TX 76011 Mr.. Thomas W. Alexion NRR Project Manager, Region IV/ANO-1 U. S. Nuclear Regulatory Commission NRR Mail Stop 11-D-23 One White Flint Nort.h 11555 Rockville Pike l
Rockville, Maryland 20852 NRC Senior Resider.t Inspector Arkansar. Nuc1 car one - ANO-1 & 2 Number 1, Nuclear Plant Road l
Russellville, AR 72801 Ms. Sheri Peterson-NRR Project Manager, Region IV/ANO-2 U. S. Nuclear Regulatory Commission NRR Mail Stop 11-D-23 One White Flint North 11555 Rockville Pike Rockv111c, Maryland 20852
.Ms. Greta Dicus, Director Division of^Radlation Control and Emergency Management Arkansas Department of Ilealth 4815 West Markham Street Little Rock, AR 72201 l
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STATE OF ARKANSAS )
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0ATil I, J. W. Yolverton, being duly sworn, subscribe to and say that I am General Mcnager, Plant Operations ANO for Entergy Operations, Inc.; that I have full authority to execute this oath; that I have read the document numbered 2CAN069107 and know the contents thereof; and that to the best of my knowledge, information and belief, the statements in it are true.
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l SUBSCRIBED AND SWORN TO before me, a Notary public in and for the County and State above named, this b day of
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PROPOSED CIIANGE This proposed change to the AND-2 Technical Specifications (TS) incorporates a new section 3/4.4.12 for low-temperature overpressure protcetion (1. TOP) including a new Bases.
TS 6.9.2 is being modified to add a new reporting requirement for reporting of events involving mitigation of an LTOP pressure transient.
These changes are a result of the ANO-2 actions for Generic Letter 90-06 for LTOP.
BACEROUND Generic Letter 90-06 was issued on June 25, 1990, regarding resolution of Generic Issue 70, " Power-Operated Relief Valve and Block Valve Reliability" and Generic Issue 94, " Additional Low-Temperaturn Overpressure Protection".
Attachment A-1 to Enclosure A of the generic letter proposed modified Standard TS on Combustion Engineering (CE) plants for power-operated relief valves (PORVs) in Modes 1, 2 and 3.
Attachment B-1 to Enclosuro B of the generic letter likewise proposed modified TS on CE plants for LTOP in Modes 4, 5 and 6.
Entergy Operations at Arkansas Nuclear One ( ANO), submitted our response to Gb 90-06 for Unit 2 on December 21, 1990.
In our response, we proposed to submit TS to address the PORVs and LTOP modified Standard TS.
Since the ANO-2 design does not utilize PORVs for LTOP, the proposed ANO-2 TS could only utilize the modified Standard TS as guidance.
DISCUSSION The ANO-2 LTOP system consists of two redundant pressure relief valves which relieve from a single discharge header on the pressurizer (See ANO-2 SAR, Figure 5.1-3).
Each LTOP relief valve is preceded by two isolation (or block) valves and connecting piping.
The LTOP relief valves are operator enabled (by opening the block valves) during cooldown when the reactor coolant system (RCS) conditions correspond to the temperature conditions where LTOP is required, and isolated from the RCS durina heatup when the RCS is above the LTOP temperature conditions.
An alarm circuit is provided to alert the operator if any block valve is not fully open under required LCS LTOP temperature conditions. The design only requires that the operator line up the relief valves during cooldown and isolate them durit.g heatup.
No other operator action is required to prevent an overpressurization event at low temperature.
Each LTOP relief valve provides a 6.38 square inch opening, which has the capacity to accommodate a worst case full safety injection initiation from a water solid RCS condition.
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in operating Modes 1, 2 and 3, the isolation valves to the I. TOP relief valves are maintained closed and perform no active safety function for LTOP.
The only derign condition where an hTOP isolation valve would be opened in Mode 1, 2 or 3, would be for valve 2CV-4740-2, which provides an ECCS vent path for depressurization in the event of a small break LOCA or a total loss of feedwater. The discharge of the ECCS vent does not pass through the LTOP relief valves and utilizes an additional motor operated isolation valve separate from j
the LTOP system (See ANO-2 SAR, Section 6.3.3.15).
Otherwise, the LTOP 1 solation valves provide for RCS pressure boundary integrity only in Modes 1, 2 and 3.
Therefore, in light of the ANO-2 design, the addition of TS for Enclosure A in Modes 1, 2, and 3 for LTOP rel!of valvo and isolation valve operability is not considered applicable to A!IO-2.
For LTOP the low temperature transient pressure-temperature (P-T) limits provide pressure restrictions for the protection against non-ductile failure under i
transient conditions. The low temperature transient P-T limits are the limits protected by the LTOP system.
These Ifmits provide the basis for the LTOP relief valve setpoint and the enable temperatures for the LTOP system.
The low temperature transient P-T limits conservatively preclude initiation of assumed
-laws by accounting for all loading conditions over a wide range of postulated flaw sizes., These loading conditions include internal pressure, pressure acting on the clad, and base metal and residual stress.
To address the I. TOP protection in Modes 4, 5 and 6 for Enclosure B to the
-generic letter, recent enalyses has been conducted by CE for ANO-2.
The analyses were performed as part ef the analyses conducted to extend the ANO-2 reactor vessel P-T limits for 21 ef fective full power years (EFPY).
The LTOP setpoint and enable temperature are typically derived from_the P-T limits in accordance with Standard Review Plan 5.2.2.
However, the ANO-2 LTOP transient P-T limits have been calculated in accordance with the new methodologies described in Combustion Engineering Owners Group (CEDG) report CEN-3Pi-P and in Attachment _1-P to CEN-381-P.
The resulting niternato limits are lest restrictivo due to replacing pre-established margins used in the ASME Code Section 111 Appendix G methodologies with more detailed fracture anchanics analysis. The results of these analyses are contained in Attachment 1,
" Low-Temperature Overpressure Protection Pressure-Temperature Limits" and
-, " Low-Temperature Overpressuto Protection Analysis".
provides the P-T limits -upon which the new LTOP setpoint and enable temperature are based, while Attachment'2 provides an assessment of the ability of the ANO-2 LTOP system to adequately accommodate the LTOP design basis transients with the new actpoint and enable temperature.
As a result of these analyses, the new ANO-2 design LTOP setpoint based on plant' specific instrument uncertainty is 450 psig and the new design enable temperature is 200 F.
The resulting ANO-2 enable temperature is 10"F loss.than that sited in Attachments 1 and 2, since the instrumentation uncertainty value used'in the CE analyses was a nominal value of 30 F.
The_ plant specific instrument uncertainty for ANO-2 has been determined to be 12*F, which was conservatively assumed as 20 F.
Therefore. the results in the CE analysis will reflect a 10'F higher temperature.
ANO-2 currently plans to maintain an actual relief valve setpoint of 430 psig (with 20 psi margin to design).
The guidelines contained in Attachment B-1 of Enclosure B of Generic Letter 90-06, were utilized in development of the ANO-2 proposed TS.
The LTOP enable temperature of 200*F coincides with the conditions of Mode 5 and 6 only, since Mode 5 is entered ct an RCS average coolant temperature of less than or equal to 200"F.
Therefore, limiting conditions for operation do not need to be applied in Mode 4 operations.
The limiting conditions for operation in the ANO-2 proposed TS in Modes 5 and 6 are consistent with the actions required by the Standard TS.
However, the proposed TS wording and Bases are tailored to the ANO-2 desired format.
The proposed surveillance requirements will ensure that when the RCS is in a condition that requires LTOP protection, an adequate vent path is available.
This will consist of verifying the LTOP relief valves or RCS vent path alignment at least once per 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.
The-proposed Bases provides information regarding the calculational methodolcgy for determining the LTOP relief valve pressure setpoint and the enable temperature setpoint, the actual AND-2 calculated setpoints, the design basis event for establishing the setpoints, the required RCS vent size, and the ASME code class and testing of the relief and isolation valves.
Based on the ANO-2 LTOP relief valve design and the conditions when LTOP is required, the proposed changes are considered to meet the requirements of Generic Letter 90-06.
DETERMINATION _0 LSI.GNIFICANT E ZARDS An evaluation of the proposed change has been performed in accordance with 10CFR50.91(a)(1) regarding no significant hazards consideration using the standards in 10CFR50.92(c).
A discussion of those standards as they relate to this amendment request follows:
Criterion 1 Does Not Involve a Significant increase in the Probability or Consequences of an Accident Previously Evaluated.
This proposed change adds additional controls to the ANO-2 TS for ensuring that LTOP is available when required. The full safety injection initiation from a water solid condition, was used in the recalculation of the ANO-2 LTOP setpoints. The methodology utilized in the LTOP setpoint analysis is based on CEOG reports CEN-381-P and Attachment 1-P to CEN-381-P.
These reports utilize improved fracture mechanics calculational methods to provide more accurate low temperature transient event modeling. Therefore, this change does not involve a significant increase in the probability or consequences of an accident previously evaluated.
Critorion 2 - Does Not Create the Possibility of a New or Dif ferent Kind of Accident-From any Previously Evaluated.
This addition to the ANO-2 TS places controls within the TS for LTOP.
The design basis event for establishing LTOP limits is a full safety injection Initiation from a water solid condition.
This event is unchanged by the l
addition of LTOP in the ANO-2 TS or the reanalysed LTOP limits.
Therefore, this change does not create a new or different kind of accident from any previously evaluated.
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Criterion _3 - Does Not Involve a Significant Reduct.Jon in the Margin of Safety.
The addition of a new section to the ANO-2 TS will have no effect on the margin
.of safety.
The LT0p margins of safety are now based on reanalyzed conditions for 21 ef fective full power years (EFpY) of operation utilizing methodology contained in CEOG report CEN-381-p ano Attachment 1 to CEN-381-P.
The liner elastic fracture mechanics (LEFM) utilized in the CEOG reports for low temperature transients is considered more appropriate than the ASME Section XI screening criteria due to explicit treatment of clad and residual st resses over a complete range of flew sizes. The safety factor expressions utilized by the CEOG reports provhle a more accurate representation of actual conditions expected under pressure loading from low temperature transients. Therefore, based on the refined expressions used to calculate ANO-2 LT0p setpoints for 21 EFPY the margin of safety will not be significantly reduced.
The Commission has provided guidance in 51 FR 7750 dated March 6, 1986, concerning the application of the standards for determining whether a significant hazards consideration exists. The proposed amendment most closely matches example (vii)
(vii)
"A change to conform a license to changes in the regulations, where the license change results in very minor changes to facility operations clearly in keeping with the reguint0 ns."
Based on the above evaluation it is concluded that the proposed TS change does not constitute a significant hazards concern.
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