NG-06-0472, Technical Specification Change Request (TSCR-083): Adoption of TSTF-478, Rev. 0, 'Bwr Technical Specification Changes That Implement the Revised Rule for Combustible Gas Control, Affected Tech Specs: Section 3.6.3.1 and 3.6.3.2

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Technical Specification Change Request (TSCR-083): Adoption of TSTF-478, Rev. 0, 'Bwr Technical Specification Changes That Implement the Revised Rule for Combustible Gas Control, Affected Tech Specs: Section 3.6.3.1 and 3.6.3.2
ML062080521
Person / Time
Site: Duane Arnold NextEra Energy icon.png
Issue date: 07/17/2006
From: Vanmiddlesworth G
Duane Arnold
To:
Document Control Desk, Office of Nuclear Reactor Regulation
References
NG-06-0472
Download: ML062080521 (30)
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Text

FPL Energy Duane Arnold, LLC 3277 DAEC Road Palo, Iowa 52324 FPLEnergy.

Duane Arnold Energy Center July 17, 2006 NG-06-0472 10 CFR 50.90 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Duane Arnold Energy Center Docket 50-331 License No. DPR-49 Technical Specification Change Request (TSCR-083): Adoption of TSTF-478, Rev. 0, "BWR Technical Specification Changes that Implement the Revised Rule for Combustible Gas Control" Affected Technical Specifications: Section 3.6.3.1 and 3.6.3.2 Pursuant to 10 CFR 50.90, FPL Energy Duane Arnold, LLC (FPL Energy Duane Arnold) hereby requests revision to the Technical Specifications (TS) for the Duane Arnold Energy Center (DAEC). The proposed Amendment revises the Limiting Condition for Operation (LCO) 3.6.3.1 to eliminate the requirement for the Containment Atmospheric Dilution (CAD) system, allowing its removal from the DAEC. LCO 3.6.3.2 is also revised to allow an additional 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> on plant start-up or shutdown sequences for the primary containment to be de-inerted. These proposed changes are consistent with those previously docketed by the Technical Specification Task Force (TSTF) as part of a generic traveler, TSTF-478, Rev. 0. The remaining portions of TSTF-478 dealing with drywell fans, purge systems, and igniters are not applicable to the DAEC's TS and are therefore not included.

FPL Energy Duane Arnold has chosen to request this TS change in advance of the completion of the Staffs generic review of the TSTF, as the CAD system at the DAEC has on-going maintenance problems and, as demonstrated in the attached application, the CAD system no longer has a safety function in the DAEC licensing basis as a result of the rulemaking revising 10 CFR 50.44 on combustible gas control in containment (68 FR 54123). Therefore, maintenance resources are being applied to comply with the current TS requirements for system Operability which are not in keeping with the true risk significance of the CAD system.

FPL Energy Duane Arnold requests approval of the proposed amendment by January 31, 2007. It is acknowledged that this date is within the one year schedule for normal processing of such license amendments. However, the TSTF on which this submittal is based was docketed in April 2005. As FPL Energy Duane Arnold has not deviated from those portions of the TSTF applicable to the DAEC design, a shorter than one year review

NG-06-0472 July 17, 2006 Page 2 of 3 schedule for this application is warranted.

In addition, the portion of this application regarding the elimination of the CAD system (a hydrogen dilution system) has a precedent in the Staffs approval of the deviations from TSTF-447, Rev. 1, the original TS changes accompanying the rulemaking to 10 CFR 50.44, for Davis Besse (Accession Number ML051780078).

The proposed Amendment presents no significant hazards consideration under the standards set forth in 10 CFR 50.92(c). Associated TS Bases changes will be completed per the TS Bases Control Program (TS 5.5.10).

This application has been reviewed by the DAEC Plant Operations Review Committee. A copy of this submittal, along with the 10 CFR 50.92 evaluation of "No Significant Hazards Consideration," is being forwarded to our appointed state official pursuant to 10 CFR 50.91.

Lastly, FPL Energy Duane Arnold would like to request that the Staff take this opportunity when issuing the safety evaluation for this amendment request to correct an oversight in the original amendment issued in response to the subject rulemaking on combustible gas control, i.e., Amendment 254 (Accession Number ML041480049). Specifically, to ensure fidelity with the original amendment request (Accession Number ML040420424), Section 4.2 of the Staffs safety evaluation for Amendment 254 should contain a clarification that the commitment for oxygen monitoring equipment is for the post-accident monitoring function only, similar to the safety evaluation issued for the Monticello plant (Accession Number ML041180612), whose application was docketed in the same submittal as the DAEC.

This letter makes no new commitments or changes to any existing commitments.

Ifyou have any questions or require additional information, please contact Mr. Tony Browning at (319) 851-7750.

I declare under penalty of perjury that the foregoing is true and correct.

Executed on July 17, 2006.

Ga Van Middlesworth Vice President, Duane Arnold Energy Center FPL Energy Duane Arnold, LLC Exhibits: A) EVALUATION OF PROPOSED CHANGE B) PROPOSED TECHNICAL SPECIFICATION AND BASES CHANGES (MARK-UP)

C) PROPOSED TECHNICAL SPECIFICATION PAGES (RE-TYPED)

NG-06-0472 July 17, 2006 Page 3 of 3 cc: Administrator, Region III, USNRC Project Manager, DAEC, USNRC Resident Inspector, DAEC, USNRC D. McGhee (State of Iowa)

EXHIBIT A EVALUATION OF PROPOSED CHANGE

Subject:

TSCR-083: Adoption of TSTF-478, Rev. 0, "BWR Technical Specification Changes that Implement the Revised Rule for Combustible Gas Control"

1. DESCRIPTION
2. PROPOSED CHANGE
3. BACKGROUND
4. TECHNICAL ANALYSIS
5. REGULATORY SAFETY ANALYSIS 5.1 No Significant Hazards Consideration 5.2 Applicable Regulatory Requirements/Criteria
6. ENVIRONMENTAL CONSIDERATION
7. REFERENCES
1. DESCRIPTION This letter is a request to amend Operating License DPR-49 for the Duane Arnold Energy Center (DAEC). The proposed Amendment would delete the Limiting Condition for Operation (LCO) 3.6.3.1, "CAD System" and its associated Bases from the DAEC Technical Specifications (TS) and would modify TS LCO 3.6.3.2, "Primary Containment Oxygen Concentration" and supporting Bases to extend the allowed time that the containment can be de-inerted, when otherwise required by the LCO Applicability, from the currently allowed 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> to 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. Deletion of the TS requirement for the CAD System will permit its removal from the plant design and licensing basis, resulting in its physical removal from the facility.

The proposed changes are consistent with those previously docketed by the Technical Specification Task Force (TSTF) as a generic traveler, TSTF-478, Rev. 0, transmitted by TSTF letter TSTF-04-12, dated April 25, 2005. The remaining portions of TSTF-478 dealing with drywell fans, purge systems, and igniters are not applicable to the DAEC's TS and are therefore not included.

2. PROPOSED CHANGE The holders of license DPR-49 for the Duane Arnold Energy Center propose to amend the Technical Specifications by deleting the referenced pages and replacing those associated with LCO 3.6.3.2 and its BASES with the enclosed new pages.

SUMMARY

OF CHANGES TS Pages BASES Pages 3.6-32 B 3.6 - 69 3.6 - 33 is deleted. B 3.6 - 70 through 73 are deleted.

3.6-34 B 3.6 - 74 B 3.6 - 75 B 3.6 - 76 B 3.6 - 77 LCO 3.6.3.1, "CAD System," and its associated Bases, are deleted from the DAEC TS. Note that the entire Specification is deleted and not relocated to a licensee-controlled document. The subsequent specification (LCO 3.6.3.2 and its Bases) will be renumbered accordingly.

The proposed revision to existing LCO 3.6.3.2, and the associated Bases, will expand the allowable time frame that the primary containment can be de-inerted, when otherwise required by the LCO Applicability, from the current 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> to 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. The addition of an LCO 3.0.4.c Note to the Actions will allow entry into the Mode of Applicability (i.e., MODE 1) while relying upon the Required Actions and associated Completion Time, which is extended to 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. A clarifying statement Page 1 of 9

is added to the Bases for Required Action A.1 to state that intentional entry into the Actions to allow the containment to be de-inerted during plant shutdowns is acceptable and not an "operational convenience" as discussed in the Bases for LCO 3.0.2. In addition, the Bases are modified to re-categorize the LCO for primary containment oxygen concentration from §50.36(c)(2)(ii), Criterion 2 to Criterion 4, based upon the subject rulemaking.

Technical Specification Bases are also modified to reflect the above changes (see Exhibit B). The Bases changes are included for information only. Bases changes will be completed per the TS Bases Control Program (TS 5.5.10).

3. BACKGROUND The Nuclear Regulatory Commission (NRC) has revised 10 CFR 50.44 to amend its standards for combustible gas control in light-water-cooled power reactors (Reference 1). In that rulemaking the Commission eliminated the design basis accident (DBA) hydrogen release from §50.44 and consolidated the requirements for hydrogen and oxygen monitoring to §50.44, while relaxing safety classifications and licensee commitments to certain design and qualification criteria for equipment needed to mitigate such combustible gas mixtures. TSTF generic Technical Specification (TS) change package, TSTF-447, Rev. 1, "Elimination of Hydrogen Recombiners and Change to Hydrogen and Oxygen Monitors," implemented the corresponding TS changes resulting from this rule change. Specifically, TSTF-447 provided model changes for license amendment applications to remove requirements for hydrogen recombiners, and hydrogen and oxygen monitors from TS. TSTF-447 was approved for adoption using the Consolidated Line Item Improvement Process (CLIIP) on September 25, 2003 (68 FR 55416). The adoption of TSTF-447 was approved for the DAEC by License Amendment 254)

(Reference 2).

As noted in the TSTF letter TSTF-04-12 (Ref. 3), additional changes to the TS as a result of the §50.44 rule change are warranted that went beyond the original content of TSTF-447. Those changes are included in TSTF-478, Rev. 0.

4. TECHNICAL ANALYSIS Elimination of the CAD System As a result of the requirements originally imposed by 10 CFR 50.44, BWRs with Mark I containment designs either installed hydrogen recombiners or credited existing CAD systems to meet requirements for hydrogen control. To ensure that a combustible gas mixture does not occur, oxygen concentration is kept < 5.0 volume percent (v/o), or hydrogen concentration is kept < 4.0 v/o. Hydrogen recombiners work to reduce the combustible gas concentration in the primary containment by recombining hydrogen and oxygen to form water vapor. The DAEC uses a CAD System, which was designed to maintain combustible gas Page 2 of 9

concentrations within the primary containment at or below the flammability limits following a postulated loss of coolant accident (LOCA) by diluting hydrogen and oxygen with nitrogen. The CAD system is only used for post-accident addition of nitrogen (UFSAR 6.2.5). A totally separate system is used at the DAEC for the initial nitrogen inerting of the containment (UFSAR 6.2.5.2.2) and DAEC also has a separate system which may be used for purging/controlled venting as part of severe accident management strategies (UFSAR 6.2.5.2.1).

The use of the CAD System in lieu of installing a hydrogen recombiner was accepted by the Staff in their Safety Evaluations issued to the DAEC in response to NUREG- 0578, Item 2.1.5.a (NUREG-0737, Item II.E.4.1) (Reference 4), and Generic Letter 84-09 (Reference 5).

From the above, it is easily seen that the hydrogen recombiners and CAD system perform the exact same function for post-LOCA gas control. Considering that the 10 CFR 50.44 rule change allowed for elimination of hydrogen recombiners for post-LOCA gas control, it follows directly that the rule change basis would likewise allow for the elimination of CAD systems.

In addition, the portion of this application regarding the elimination of the CAD System (a hydrogen dilution system) has a precedent in the Staffs approval of the deviations from TSTF-447, Rev. 1, the original TS changes accompanying the rulemaking to 10 CFR 50.44, for Davis Besse (Accession Number ML051780078).

Changqes to the Primary Containment Oxygen Concentration Specification The Applicable Safety Analysis section of the Bases to LCO 3.6.3.2, Primary Containment Oxygen Concentration, currently states that the LCO satisfies 10 CFR 50.36(c)(2)(ii) Criterion 2. Criterion 2 is "A process variable, design feature or operational restriction that is an initial condition of a design basis accident or transient analysis that either assumes the failure of or presents a challenge to the integrity of a fission product barrier." As noted above, a combustible gas mixture is no longer postulated to occur as a result of any DBA. Thus, the DAEC UFSAR accident analyses for evaluating combustible gas mixtures from a design basis LOCA, performed pursuant to Safety Guide 7 (Regulatory Guide 1.7, Rev. 1) is no longer part of the DAEC licensing basis with the issuance of Amendment 254 and was subsequently removed from the DAEC UFSAR during the last update, pursuant to 10 CFR 50.71(e). Therefore, LCO 3.6.3.2 no longer meets the definition of Criterion 2. However, the regulatory analysis for the revised 50.44 rule change also concluded that combustible gases produced by severe (i.e., beyond design basis) accidents, involving both fuel-cladding oxidation and core-concrete interaction, would be risk significant for plants with Mark I containments, such as DAEC, if not for the inerted containment atmosphere. Thus, the final rule retains the existing requirement in 50.44(c)(3)(i) to inert Mark I containments. Thus, given the change in status of being needed Page 3 of 9

for severe accidents and not for a DBA, the Bases are revised to state that the LCO now meets 10 CFR 50.36(c)(2)(ii) Criterion 4 vice Criterion 2. Criterion 4 is "a structure, system, or component which operating experience or probabilistic risk assessment has shown to be significant to public health and safety."

In keeping with the above change in status from mitigating a DBA to being relevant to risk for coping with beyond design basis (a.k.a. severe) accidents, the allowable outage time (i.e., the Completion Time) in the existing LCO for Primary Containment Oxygen Concentration (LCO 3.6.3.2) is being extended from the existing 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> to 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. This allowance is generally used during initial startup operations to maintain the primary containment de-inerted and again during the shutdown process to de-inert the primary containment to allow personnel entry. However, the current 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> "window" to perform the inerting/de-inerting evolution creates operational hardships that are not commensurate with the risk of the beyond design basis event requiring the primary containment to be inerted to combustible gas mixtures.

Specifically, inerting the primary containment is an operational problem because it prevents containment access without an appropriate breathing apparatus.

Therefore, the primary containment is permitted to be de-inerted for a short period of time following plant startup to facilitate containment access to perform required inspections during startup. The use of the LCO 3.0.4.c provision will allow the containment to remain de-inerted for up to 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> after entry into MODE 1 to permit containment entries to perform inspections or any needed repairs just after startup. It also allows the process of inerting the containment to be performed after the plant has reached steady state (i.e., full power) conditions, rather than during the plant startup process, when many other activities and Surveillances are being performed. The inerting/de-inerting process is complex (feed and bleed) and requires Operator vigilance to avoid exceeding the trip setting for Reactor Protection System (RPS), Emergency Core Cooling System (ECCS) and Primary Containment Isolation System (PCIS) on high containment pressure, which is nominally set at 2 psig at DAEC.

The current 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> allowance is sometimes not sufficient to prevent the inerting activity from becoming a critical path activity during startup/power ascension and can interfere with the performance of other required Surveillances (such as scram time testing at approximately 30% power), as the 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> clock is likely to expire before this testing can be completed. The first 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> of a plant startup is typically the most likely time for a maintenance issue to surface. For example, a maintenance issue can arise in the balance of plant during startup, which requires repair prior to continued power ascension. Meanwhile, the 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> clock to inert the primary containment is continuing to run. This can result in the Operators having to shift focus away from the repair activity to complete the inerting process within this short 24 window. Such "starting and stopping" is an Operator distraction that is not warranted. By allowing the inerting process to occur 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> after entering the Mode of Applicability, the likelihood of such an interruption is minimized.

Page 4 of 9

In addition, the Completion Time of 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> for Required Action A.1 will allow the containment to be de-inerted earlier in the routine plant shutdown process.

This eliminates a complex task from the shutdown process, when many other activities are underway requiring Operator vigilance. The current provision of 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> prior to shutdown requires estimating when the Mode of Applicability (i.e.,

MODE 1) will be exited, so that the 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> clock can be started appropriately.

Any interruption or delay in the shutdown process can cause the plant to stop the de-inerting process and re-inert the containment in order to comply with the LCO.

Such "starting and stopping" is an Operator distraction that is not warranted. By allowing the de-inerting process to occur 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> prior to exiting the Mode of Applicability, the likelihood of such an interruption is minimized.

Per the technical analysis supporting the rulemaking to 10 CFR 50.44 (Reference 6), the likelihood of the beyond design basis event that leads to a combustible gas mixture is very low. Combustible gas mixtures are a result of core damage events and not part of the accident sequence leading up to core damage. Thus, the proposed extension of the allowance for the containment to be de-inerted has no impact on Core Damage Frequency (CDF). As noted in Reference 6, the impact on containment failure probability is generally after the initial 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> period after core damage has occurred. Thus, the impact on Large Early Release Frequency (LERF) is deemed to not be significant, assuming the containment was initially inerted. However, the additional 48 hour5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> allowance above the current 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> is judged to not be a risk-significant increase in LERF, as the additional time the containment will be de-inerted while in the Mode of Applicability will be only a 1.2% increase annually (assuming one plant shutdown and startup sequence per year = 96 additional hours de-inerted and a 30 day shutdown). Per Reference 6, it was judged that the conditional probability of a large early release approached unity (1.0) if a Mark I containment was not inert at the onset of core damage. With this assumption, using the baseline LERF value for the DAEC of 1.39 E-6/yr (Rev. 5C), a 1.2% increase would yield a delta-LERF (ALERF) value of 1.67 E-8, which is within the guidelines of Regulatory Guide (RG) 1.174 for an acceptable increase (i.e., < 1.0 E-7).

5. REGULATORY SAFETY ANALYSIS 5.1 No Siqnificant Hazards Consideration FPL Energy Duane Arnold has evaluated whether or not a significant hazards consideration is involved with the proposed amendment by focusing on the three standards set forth in 10 CFR 50.92, "Issuance of amendment," as discussed below:
1. Does the proposed amendment involve a significant increase in the probability or consequences of an accident previously evaluated?

Response: No.

Page 5 of 9

The Containment Atmosphere Dilution (CAD) system and primary containment oxygen concentration are not initiators to any accident previously evaluated in the DAEC Updated Final Safety Analysis Report (UFSAR). The CAD system and containment oxygen concentration were previously relied upon to mitigate the consequences of a design basis accident (DBA) combustible gas mixture. However, the revised 10 CFR 50.44 (68 FR 54123) no longer defines a DBA hydrogen release (i.e., combustible gas mixture) and the Commission has subsequently found that the DBA loss of coolant accident (LOCA) hydrogen release is not risk significant. In addition, hydrogen control systems, such as CAD, have been determined to be ineffective at mitigating hydrogen releases from the more risk significant beyond design basis accidents that could threaten containment integrity. Therefore, elimination of the CAD system will not significantly increase the consequences of any accident previously evaluated. The consequences of an accident while relying on the revised Required Actions for primary containment oxygen concentration are no different than the consequences of the same accidents under the current Required Actions. As a result, the consequences of any accident previously evaluated are not significantly increased.

Therefore, the proposed change does not involve a significant increase in the probability or consequences of an accident previously evaluated.

2. Does the proposed amendment create the possibility of a new or different kind of accident from any accident previously evaluated?

Response: No.

No new or different accidents result from utilizing the proposed change. The changes do not involve a physical alteration of the plant, except for the elimination of the CAD system (i.e., no new or different type of equipment will be installed) or a change in the methods governing normal plant operation. The CAD system is not considered an accident precursor, nor does its existence or elimination have any adverse impact on the pre-accident state of the reactor core or post accident confinement of radionuclides within the containment building from any DBA. In addition, the changes do not impose any new or different requirements. The changes to the Technical Specifications for oxygen concentration do not alter assumptions made in the safety analysis, but reflect changes to the safety analysis requirements allowed under the revised 10 CFR 50.44. Specifically that an inerted containment is no required to mitigate any DBA, but has been found to be helpful in mitigating certain beyond design basis events (i.e., severe accidents) that could generate combustible levels of hydrogen.

Therefore, the proposed change does not create the possibility of a new or different kind of accident from any previously evaluated.

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3. Does the proposed amendment involve a significant reduction in a margin of safety?

Response: No.

The installation of combustible gas control systems, such as CAD, required by the original §50.44(b)(3) was intended to address the limited quantity and rate of hydrogen generation that was postulated from a design-basis LOCA. The Commission has found that this hydrogen release is not risk-significant because the design-basis LOCA hydrogen release does not contribute to the conditional probability of a large release up to approximately 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> after the onset of core damage. In addition, these systems were ineffective at mitigating hydrogen releases from risk-significant accident sequences that could threaten containment integrity.

(68 FR 54123). The proposed changes to CAD and primary containment oxygen concentration reflect this new regulatory position and, in light of the remaining plant equipment, instrumentation, procedures, and programs that provide effective mitigation of and recovery from reactor accidents, including postulated beyond design basis events, does not result in a significant reduction in a margin of safety.

Therefore, the proposed change does not involve a significant reduction in a margin of safety.

CONCLUSION Based on the preceding 10 CFR 50.92 evaluation FPL Energy Duane Arnold concludes that the proposed amendment presents no significant hazards consideration under the standards set forth in 10 CFR 50.92(c), and, accordingly, a finding of "no significant hazards consideration" is justified.

Attorney for Licensee: Robert E. Helfrich, Esquire Senior Attorney, Florida Power and Light Company, 700 Universe Blvd, Juno Beach, FL 33408 Page 7 of 9

5.2 Applicable Regulatory Requirements/Criteria By letter dated July 17, 2006, FPL Energy Duane Arnold submitted a request for revision of the TS for the DAEC. The proposed amendment would delete the TS Limiting Condition for Operation (LCO) 3.6.3.1 and modify LCO 3.6.3.2 to extend the allowable time for the primary containment to be de-inerted, when otherwise required by the LCO Applicability.

Evaluation:

The proposed changes are consistent with the current regulations and thus, an exemption pursuant to 10 CFR 50.12 is not required. The current regulations (e.g.,

§50.36) only require LCOs be included in the TS that satisfy the criteria listed in

§50.36(c)(2)(ii). The elimination of the CAD LCO is warranted, as its previous inclusion in TS was based upon satisfying Criterion 3, as a system required to mitigate a DBA. With the rule change to §50.44, the DBA hydrogen release has been re-categorized as a beyond design-basis or severe accident. The rule change also deemed that current combustible gas control systems, such as CAD, were not capable of dealing with the severe accident cases. Thus, the CAD LCO would not satisfy Criterion 4 either. Therefore, the elimination of the CAD LCO from TS is consistent with the requirements of §50.36.

The same rulemaking determined that having the primary containment inert at the beginning of these beyond design-basis events that generate significant quantities of combustible gas was risk significant. Thus, the re-categorization of the LCO for primary containment oxygen concentration from Criterion 2, which applies to DBAs, to Criterion 4, which is associated with risk, is consistent with the change in regulations. In keeping with the Criterion 4 designation, the extension in the time allowance for the containment to be de-inerted has been evaluated to not be a significant increase in risk.

In conclusion, based on the considerations discussed above, (1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, (2) such activities will be conducted in compliance with the Commission's regulations, and (3) the issuance of the amendment will not be inimical to the common defense and security or to the health and safety of the public. Therefore, FPL Energy Duane Arnold has concluded that the proposed revision to the DAEC Technical Specifications is acceptable.

6. ENVIRONMENTAL CONSIDERATION 10 CFR Section 51.22(c)(9) identifies certain licensing and regulatory actions which are eligible for categorical exclusion from the requirement to perform an environmental assessment. A proposed amendment to an operating license for a facility requires no environmental assessment if operation of the facility in accordance with the proposed amendment would not: (1) involve a significant Page 8 of 9

hazards consideration; (2) result in a significant change in the types or significant increase in the amounts of any effluents that may be released offsite; and (3) result in a significant increase in individual or cumulative occupational radiation exposure.

FPL Energy Duane Arnold has reviewed this request and determined that the proposed amendment meets the eligibility criteria for categorical exclusion set forth in 10 CFR Section 51.22(c)(9). The basis for this determination follows.

Basis

1. As demonstrated in the 10 CFR 50.92 evaluation included in this exhibit, the proposed amendment does not involve a significant hazards consideration.
2. The proposed changes do not result in an increase in power level, do not increase the production, nor alter the flow path or method of disposal of radioactive waste or byproducts. There is no significant change in the types or significant increase in the amounts of any effluents that may be released offsite.
3. The proposed changes do not result in changes in the level of control or methodology used for processing of radioactive effluents or handling of solid radioactive waste nor will the proposal result in any change in the normal radiation levels within the plant. There is no significant increase in individual or cumulative occupational radiation exposure.

Pursuant to 10 CFR Section 51.22(b), no environmental impact statement or environmental assessment needs to be prepared in connection with the issuance of the amendment.

7. REFERENCES
1. 68 FR 54123 (Combustible Gas Control in Containment), September 16, 2003.
2. D. Beaulieu (USNRC) to M. Peifer (NMC), "Duane Arnold Energy Center -

Issuance of Amendment Re: Relocation of Requirements for Hydrogen and Oxygen Monitors (TAC NO. MCI 900)," June 10, 2004.

3. Technical Specification Task Force letter, TSTF-04-012, "Submittal and Request for Fee Waiver for Review of TSTF-478, Revision 0, "BWR Technical Specification Changes that Implement the Revised Rule for Combustible Gas Control," dated April 25, 2005.
4. NRC Letter, T. Ippolito (USNRC) to D. Arnold (IELP), "Evaluation Of Licensee's Compliance With Category "A" Items Of NRC Recommendations Resulting From TMI-2 Lessons Learned," dated March 10, 1980.
5. NRC Letter, M. Thadani (USNRC) to L. Liu (IELP), "Safety Evaluation Regarding Hydrogen Recombiner Capability," dated June 3, 1986.
6. SECY-00-0198, "Status Report on Study Of Risk-Informed Changes to the Technical Requirements of 10 CFR Part 50 (Option 3) and Recommendations on Risk-Informed Changes to 10 CFR 50.44 (Combustible Gas Control)," dated September 14, 2000.

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EXHIBIT B PROPOSED TECHNICAL SPECIFICATION AND BASES CHANGES (MARK-UP) 13 Pages to Follow

CAD Sys em

3. .3.1 3.6 CONTAT ENT SYSTEMS 3.6.3.1 ontainment Atmosp re Dilution (CAD) S stem LCO 3.6.3.1 The C System shall be.OP LE.

APPLICABILITY: E 1 when the Primar Containment nmn is re ired to be nerted per LCO 3.6. .2. "Primary Contai ment Oxygen oncentration."

ACTIONS DTION I REQUIRED ACT! I*' TIME r

inoperabl A.1 Restore CAD 7 d/as System* o OPERABLE statu.

I ACAD System B. Required Acon and B.1 e in MODE 3. 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> associate Completion Time not t.

Pages 3.6 -32 and 3.6 - 33 are deleted. I DAEC 3.6-32 Amendmenit 223

J i CAD Syste 3.6.3 SURVEI LLANC/REQUI REMENTS //

SU7 LLANCEFRXUENCY

Ž:67,000 scf of nit ogen is 3/days

/SR3.6.3.1.1 'Verif SR 3.6.3.1.2 Verify by administr tive means that each 31 days CAD System manua ,power operated and automatic valv in the required flowpath(s) t at is not locked, sea/ed,

/or otherwis secured in position in the corre position or can be igned to the cor ct position.

I DAEC 3.6-33 Afflendffient 243

Primary Containment Oxygen Concentration 3.6.3 3.6 CONTAINMENT SYSTEMS 3.6e3./ Primary Containment Oxygen Concentration 1W LCO The primary containment oxygen concentration shall be

< 4.0 volume percent.

MODE-LInsert a period "." here.

APPLICABILITY: MODE 1Ing t,,-I-h tifne p*rio.d

a. rorr 24. hou s after TH L POWER is > 15%R P followhng startup,
  • LO3- NOTE LCO 3.0.4.c is applicable.  ; 224 hour0.00259 days <br />0.0622 hours <br />3.703704e-4 weeks <br />8.5232e-5 months <br /> prior to educing THEIAL POWER < 15% P prior o reactor utdown.

\ýAC-TI ONS CONDITION REQUIRED ACTION COMPLETION TIME A. Primary containment A.1 Restore oxygen *hours oxygen concentration concentration to not within limit, within limit.

B. Required Action and B.I --Red.ee-. ERMA,-PGOW 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> associated Completion " to 1 RTP.

Time not met.

SURVEILLANCE REQUIREMENTS SURVEILLANCE FREQUENCY SR 3.6.3. .1 Verify primary containment oxygen 7 days concentration is within limits.

ATSCR083 2 DAEC 3.6-34 A.,,endment 223

CAD ystem 3.6.3.1 B 3.6 CONTA MENT SYSTEMS B 3.6.3. Containment Atmosphere lution (CAD) System BA BACKGROUND The C System functions to maintain ostulated combustible gas oncentrations within the prima containment at or b ow the flanmmability limits fol wing a Loss of Coolant ccident (LOCA) by diluting hydr gen and oxygen with nitrogen. To ensure that a c ustible gas mixture does not occur, oxygen concentration J kept < 5.0 volume percent (v/o).

The CAD System is manua y initiated and consists of a nitrogen storage bank nd two independent, 100% capacit nitrogen injection s systems. Each nitrogen injecti subsystem includes he pressure regulating valves, ntrol valves and conne ed piping necessary to transport itrogen from the storag bank to the drywell and suppres on chamber volumes. CAD ystem OPERABILITY is not affect by the inability of the pressure regulators to regul e pressure, because re ulator failure does not affect t CAD Systems ability inject the required volume of trogen into the contai ent. The failure of the pressur regulators does not r sult in any piping being subject to a pressure gre er than design. The nitrogen s rage bank contains

>/7,000 scf, which is adequate for days of CAD System peration. The nitrogen cylinder that make up the storage bank, and the header up to the rst normally closed valve in each of the redundant suppl lines constitute a "passive" system and, accordingly, are ot subject to the single failure criterion that ;app es only to "active" components.

Therefore, it is not nec sary that the CAD nitrogen storage bank be redundant.

The CAD System woul pically be operated to add nitr en in a step-wise fas on to dilute combustible gases. fter approximately 36 ays, containment pressure buildup ay be sufficient to rquire venting.

APPLICABLE To evalua the potential for hydrogen and gen SAFETY ANALYSES accumultion in primary containment follo ing a LOCA, hydrog and oxygen generation is calcul ed (as a function of following the initiation of th accident). The (continued)

DAEC Pages B3.6" 69 thr-ugh B 3.6 - 73 are deleted.

B 3.6-69 3 TSCR-J04<I

CAD System B 3.6.3.1 tDA C*C APPLICABLE conservative assumptions ated in Reference 1 are used to SAFETY ANALYSES maximize the amount of h drogen and oxygen generated. The (continued) calculation confirms t t when the CAD system is actuate within 2.3 days after a LOCA, the peak oxygen concentra on in primary containm t is < 5.0 v/o (Ref. 2).

Hydrogen and oxy n may accumulate within primary containment fo owing a LOCA as a result of:

a. A met water reaction between the zirc ium fuel rod cia ing and the reactor coolant; or
b. diolytic decomposition of water i the Reactor Coolant System.

T CAD System satisfies Criterion 3 f 10 CFR

.36(c)(2)(ii).

LCO The CAD System must be OPERABL . The CAD System is considered to be OPERABLE if itrogen can be injected into both the drywell and suppre sion chamber volumes via any combination of components n either nitrogen injection subsystem (i.e., the CAD ystem is considered to be OPERA E if one nitrogen inject" n subsystem is capable of injec ng into the drywell and e other nitrogen subsystem is c able of injecting into t suppression chamber volume). T is ensures operation f the CAD System in the event of n accident of suff* ient magnitude to generate hydro en in significant a nts. Operation of the CAD Syste is designed to m ntain primary containment post- CA oxygen concentrati < 5.0 v/o for 7 days.

APPLICJABILITY In MOD 1, the CAD System is required to aintain the oxygen conce ration within primary containmen below the fla bility limit of 5.0 v/o followin a LOCA. The CAD Sy em is not capable of inerting th containment from rmal atmospheric concentration le els; it can only dilute the oxygen concentration to below, he flammability limit once an inerted atmosphere has b en initially established by (continued)

TSCR-O44~~

DAEC B 3.6-70 B 3.6-70 TSCR-b44,M1

CAD System B 3.6.3.1 BASES APPLICABILITY other means. Because the stem is not capable of (continued) performing its intended s ety function. i.e.. it is t OPERABLE. until an inert d atmosphere has been estab shed.

the Mode 1 APPLICABILIT has been modified to allow he LCO to not be entered unti the Primary Containment ha been inerted per LCO 3.6.3.2. "Primary Containment Oxy en Concentration". Thi ensures that the relative eak tightness of prima containment is adequate an prevents damage to safety lated equipment and instru nts located within primary c tainment. In MODE 3, both he hydrogen and oxygen prod ction rates and the total a unts produced after a LOCA w uld be less than those calc ated utilizing the conservat've assumptions contained in ef. 1. Thus. if the analysi were to be performed starti g with a LOCA in MODE 3, th time to reach a flammable c ncentration would be extended yond the time conservativel calculated for MODES I and 2. The extended time would all w hydrogen removal from th primary containment atmosp re by other means and also a low repair of an inoperable itrogen injection subsy tem, and/or nitrogen storag bank, if CAD were not avai able. Therefore, the CAD S tem is not required to be OP BLE in MODE 3.

n MODES 4 and 5, the probabi ity and consequences of a LOCA are reduced due to the press re and temperature limitations of these MODES. Therefore, the CAD System is not required to be OPERABLE in MODES 4 nd 5.

A.1I With the CAD System J operable, the CAD System must restored to OPERABL status within 7 days. The 7 y Completion Time is ased on the low probability o thE occurrence of a L CA that would generate hydroge in the amounts capable f exceeding the flammability l it, the amount of time vailable after the event for o erator action to prevent ex eding this limit, and the avai ability of other hydrog mitigating systems.

(con tinued) I B 3.6-71 TSCR- .5°3 DAEC

D System B 3.6.3.1 BASES ACTIONS B.1 (continue If any Required ction cannot be met withi the associated Completion Ti , the plantatmust 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.

to a MODE in brought to leastbe MODE brough within based which plant must the LCO does not apply. To achiev this status, is reasonable, the Time of 12 hour 3 from full power MOe The operatng on experience, to reach allowe Completion

/

/ s in an orderly manner and/without challenging

~conditigmustems.

plant

/ REQU IREMENTS// is > 67/000 nitrogen scf 7ofdays supply CAse of post-LOCA in/

/ y~erifying that there will ensure t least the CAD System of 14 This volume i/referenced to a pressure

/operation.

This an accident minimum to of/

volume

/ psia temperature and aallows suffici t time after e o /32°F.

/nitrogen inerting. This the nitrogen supply for long term system replenish to ensure that the verified every 31ays his capable of performi its intended function when re ired.

The 31 day Frequen is based on operating experie ce, which has shown 31 days to be an acceptable period to v rify the nitrogen supply nd on the availability of other hydrogen mitigating sys ms.

SR 3.6.3.1.2 Verifyin by administrative means the co sect alignment for manual, ower operated and automatic va es necessary to establish CAD System OPERABILITY requi es the valves neces ary to allow nitrogen injection into both the drywell and uppression chamber volumes via ny combination of co onents in either nitrogen inje ion subsystem to be in t e correct position. This provi s assurance that the roper flow paths exist for syst operation. This SR does not apply to valves that are lo ed, sealed, or otherwise secured in position, since the e valves were verified to e In the correct position prio to locking, sealing, or securing.

(continued)

3. - 2TS R 5 I~

DA CB DAEC B 3.6-72 TSC U-K-nJ

JI I

CAD System B 3.6.3.1 BASES SURVEI LLANCE SR 3.6.3.1.2 (co inued)

REQUIREMENTS A valve is also llowed to be in the non cident position provided it ca be aligned to the accid t position within the time ass ed in the accident analy is. This is acceptable cause the CAD System is anually initiated.

This SR do s not require any testin or valve manipulation; rather, ' involves verification t t those valves capable of bein mispositioned are in the correct position. This does t apply to valves that ca not be inadvertently I misa gned, such as check valv .

T 31 day Frequency is appr priate because the valves are erated under procedural I

ntrol, the probability of an event requiring initiatia of the system is low, an the system is a manually mi iated system.

F REFERENC ES 1. Safety GuideN . 7.

2. UFSAR, Sect' n 6.2.5.

/

/ /

DAEC B 3.6-73 TSCR-gP

Primary Containment Oxygen Concentration B 3.6.3./

w B 3.6 CONTAINMENT SYSTEMS B 3.6.y' Primary Containment Oxygen Concentration BASES BACKGROUND Nuclear power pla s must be desi ed to withstand vents that generate h nrogen either d to the zirconi metal water reaction in the core or e to radiolysis The Insert to BACKGROUND primary meth to control hy ogen in Mark I C tainment is to inert th primary contai nt. With the p imary containme inert, that i oxygen concentr ion

< 4.0 vo ume percent (v/). a combustible xture cannot be presen in the primary ontainment for a hydrogen conce ration. The c pability to inert he primary con inment and mai amn oxygen < 4.0 /o works together wi the Containmet Atmosphere Dil on System CO 3.6.3.1. 'Citainment Atmosphe Dilution (CAD) ystem") topro ide redundant and iverse methods to mitigate evený that produce hydr gen. For example.

postulated ent that rapidly gferates hydrogen fr zirconium tal water reactio will result in exce ive hydrogen *n primary containmn t, but oxygen conce ration will re in < 4.0 v/o and n combustion can occu . Long term neration of both h rogen and oxygen fr radiolytic deco osition of water m eventually result i a co ustible mixture in rimary containment. xcept that the C System dilutes hy ogen and oxygen gas faster than hey can be produced rom radiolysis and ain no combustion can occur. This L ensures that oxyge concentration does not exceed 4.0 v/ during operation in he applicable conditions.

APPLICABLE The Reference calculations a ume that the pr mary SAFETY ANALYSES containment s inerted when esign Basis Ac dent loss of coolant a ident occurs. A hough the amou of hydrogen generat as a result of DBA LOCA with s cessful ECCS miti ion is < 1%. lar amounts of hydr en generationon 0i. : 5%) are postu ted to occur in ccordance with S ety Guide 7. Thu . the hydrogen as ed to be rele ed Insert to APPLICABLE o the primary cont inment as a resul of metal water SAFETY ANALYSIS reaction in the r ctor core will n produce combus ible gas mixtures in e primary contai nt. Oxygen. ich is subsequently g erated by radiol ic decompositio of water, (continued)

AmnCe'°83 DAEC B 3.6-74 ....

  • AmcndmcnItI~lG 223

TSCR-083 Insert to BACKGROUND:

The Reference 1 Final Rule removed the definition of a design-basis LOCA hydrogen release and eliminated requirements for hydrogen control systems to mitigate such a release at currently-licensed nuclear power plants. However, the supporting analysis for this rulemaking concluded that combustible gases produced by beyond design-basis accidents, involving both fuel-cladding oxidation and core-concrete interaction, would be risk significant for plants with Mark I and II containments if not for the inerted containment atmosphere. Given the relatively small volume and large zirconium inventory, these containments, without inerting, would have a high likelihood of failure from hydrogen combustion due to the potentially large concentration of hydrogen that a severe accident could cause. With the primary containment inert, that is, oxygen concentration < 4.0 volume percent (vlo), a combustible mixture cannot be present in the primary containment for any hydrogen concentration. Thus, the Final Rule required plants with Mark I and II containments to maintain the containment atmosphere with a low concentration of oxygen (i.e., < 4.0 v/o), rendering it inert to combustion.

Insert to APPLICABLE SAFETY ANALYSIS:

The Reference I evaluation assumes that the primary containment is inerted when an event with significant core damage occurs. Thus, the hydrogen assumed to be released to the primary containment as a result of degraded core conditions is not likely to produce combustible gas mixtures in the primary containment.

Primary Containment Oxygen Concentration B 3.6.3.

I BASES APPLICABLE is diluted and removed by the CAD yst... ... re....ridly than SAFETY ANALYSES it is produced. Primary containment oxygen concentration (continued) satisfies Criterion Xo-f10 CFR 50.36(c)(2)(ii).

LCO The primary containment oxygen concentration is maintained

< 4.0 v/o to ensure that an event tht P,*rou e,,an -,amun of hydrogen does not result in a combustible mixture inside primary containment. iabeyond-design basis event that can produce significant amounts APPLICABILITY The primary containment oxygen concentration must be within the specified limit when primary containment is inerted/fl exmet as -Xowed bythe rellaxatioris du, ing startup anid s I 64d., a ddessed beuiw. The primary containment must be inert in MODE 1. since this is the condition with the highest probability of an event that could produce hydrogen.

Inerting the prim containment

  • an operational pfoblem because it prev ts containment ccess without an appropriate br athing apparatu Therefore, the imary containment *s inerted as la as possible in th plant startup an de-inerted as son as possible in e plant shutdown As long as rea or power is < 15% P. the potenti for an event t at generates signif cant hydrogen is 1 and the primary ontainment need no be inerted.

Fur ermore. the prob ility of an event at generates si ificant amounts f hydrogen occurri within the first hours of a star up. or within the 1 t 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> before shutdown, is low nough that these "wndows." when the primary contai nt is not inerted. re also justified. The 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> time eriod is a reasonabl amount of time to low plant perso el to perform inerti g or de-inerting. uring reactor st rtups. a convenient d conservative star time for redu ng primary containme t oxygen concentrat* n to less t n 4.0 v/o within 24 urs occurs when the e switc is placed in Run. SJ ilarly, during rea or sh owns, limiting the ti oxygen can exceed .0 v/o to 24 ho s prior to taking th mode switch out of n is also nservative.

(continued)

A TsC'83 -

DAEC B 3.6-75

Primary Containment Oxygen Concentration A Note to the Actions permits the use of the provisions of B 3.6.3.

LCO 3.0.4.c. This allowance permits entry into the Mode 1 BASES (continued) of Applicability while relying on the Actions.

Intentional entry into the Conditions and ACTIONS A.1 Required Actions is permitted during the reactor startup and shutdown process.

If oxygen concentration is

  • 4.0 v/o at any time while operating in MODE 1. w'ith the,xe-pti, n of the r-laxati-n /

a,&I owed--du,,,ktfr-f-tartupv and-shutdew- oxygen congentration must be restored to < 4.0 v/o within 24j.hurs. 4our

-The Completion Time is allowed when oxygen concentration is 2 4.0 v/o because of the availability of other hydrogen 2 I miti,, n awem-ey,*t fe.g.. ,theAD System) and the low probability, and long duration of an event that would generate significant amounts of hydrogen occurring during this period.

B.1 If oxygen concentration cannot be restored to within limits within the required Completion Time. the plant must be brought to a MODE in which the LCO does not apply. To ,,,E2 achieve this status, power must be reduced to

  • 15% RTP-i'" iI within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />. The 8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> Completion Time is reasonable.

based on operating experience, to reduce reactor power from full power conditions in an orderly manner and without challenging plant systems.

SURVEILLANCE SR 3.6.3. .1 REQUIREMENTS The primary containment must be determined to be inert by verifying that oxygen concentration is < 4.0 v/o. The 7 day Frequency is based on the slow rate at which oxygen concentration can change and on other indications of abnormal conditions (control room alarms for containment high oxygen concentration, excessive cycling of the Containment Nitrogen Makeup System or unexplained changes in containment pressure). Indication of abnormal conditions would lead to more frequent monitoring of primary containment oxygen concentration. Also. this Frequency has been shown to be acceptable through operating experience.

(continued)

DAEC B 3.6-76 Ame-d".ent 223

Concentration Primary Containment Oxygen Primary Contai nment Oxygen Concentrati on B 3.6 g3 BASES (continued)

REFERENCES 1. REFERENCES uFr,.*ll* * *, r IFederal SectLion3 6.2-.5. Combustible Control68in FR Gas Notice Register 54123 Containment, Fin Final SRule, dated September 16, 2003.

TSCR-083 DAEC B 3.6-77 Amendmeint 223

EXHIBIT C PROPOSED TECHNICAL SPECIFICATION PAGES (RE-TYPED) 2 Pages to Follow

Pages 3.6-32 and 3.6-33 are deleted.

DAEC 3.6-32 Amendment

Primary Containment Oxygen Concentration 3.6.3.1 3.6 CONTAINMENT SYSTEMS 3.6.3.1 Primary Containment Oxygen Concentration I l

LCO 3.6.3.1 The primary containment oxygen concentration shall be

< 4.0 volume percent.

APPLICABILITY: MODE 1. I ACTIONS

NOTE- -----------------------------

LCO 3.0.4.c is applicable.

CONDITION REQUIRED ACTION COMPLETION TIME A. Primary containment A.1 Restore oxygen 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> oxygen concentration concentration to not within limit, within limit.

B. Required Action and B.1 Be in MODE 2. 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> associated Completion Time not met.

SURVEILLANCE REQUIREMENTS SURVEILLANCE FREQUENCY SR 3.6.3.1.1 Verify primary containment oxygen 7 days concentration is within limits.

DAEC 3.6-34 Amendment

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