ML20235F464
| ML20235F464 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 09/21/1987 |
| From: | SACRAMENTO MUNICIPAL UTILITY DISTRICT |
| To: | |
| Shared Package | |
| ML20235F454 | List: |
| References | |
| NUDOCS 8709290134 | |
| Download: ML20235F464 (8) | |
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1 ATTACHMENT I RANCHO SECO TECHNICAL SPECIFICATIONS (Pages affected by Proposed Amendment No. 162) i 8709290134 870921 PDR ADOCK 05000312 P PDR
n' RANCHO SECO UNIT 1 TECHNICAL SPECIFICATIONS Limiting' Conditions for Operation i: 3.24 EXPLOSIVE GAS MIXTURE l
1624 The concentration of oxygen in the Waste Gas Holdup System shall be limited to 5 4% by volume,' except when the system is drained,
+; purged, isolated and in an out-of-service condition.
Applicability At all times Action
- 162
- A. With the concentration of oxygen in the Waste Gas Holdup System >4%
by volume, immediately suspend all additions of waste gases to the system, and reduce the oxygen concentration to 14% within 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br />.
162+ B. When any part of the Waste Gas System is to be removed.from service and/or opened-to the atmosphere, first ensure that the hydrogen concentration is 5 4% and that all sources of hydrogen have been eliminated. .The oxygen concentration limit is not applicable when the system is drained. purged, . isolated and in an out-of-service-
+ condition.
Bases This specification is provided to ensure that the concentration of 162t potentially explosive gas mixtures contained in the Waste Gas Treatment
+ System is maintained below the flammability limits of hydrogen and oxygen.
Maintaining the concentration of oxygen below the flammability limit provides assurance that the releases of radioactive materials wili be controlled in conformance with the requirements of General Design Criterion 60 of Appendix A and 10 CFR Part 50.
1624 The requirements of this specification are not violated when the Waste Gas Holdup System is drained, purged, isolated, and in an out-of-service
+ condition.
Proposed Amendment No.162 3-89
i RANCHO SECO UNIT 1 TECHNICAL SPECIFICATIONS l Limiting Conditions for Operation 4.28 EXPLOSIVE GAS MIXTURE Surveillance Requirements 1624& The concentration of oxygen in the Waste Gas Holdup System shall be determined to be within the limits specified in 3.24 by continuously 1624& monitoring the waste gases in the Waste Gas Hold-up System with the oxygen monitor demonstrated OPERABLE according to Table 4.28-1. If the continuous monitor 'is inoperable, a daily sample will be taken and analyzed; during heatup or cooldown, a sample will be taken and analyzed within four hours.
1624 Sampling shall not be required when the Waste Gas Holdup System is drained,
& purged, isolated, and in an out-of-service condition.
Bases This specification is provided to ensure that the concentration of 1624 potentially explosive gas mixtures contained in the Waste Gas Treatment
& System is maintained below the flammability limits of hydrogen and oxygen.
Maintaining the concentration of oxygen below the flammability limit provides assurance that the releases of radioactive materials will be controlled in conformance with the requirements of General Design Criterion 60 of Appendix A and 10 CFR Part 50.
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Proposed Amendment No.162 4-87 !
ATTACHMENT II FACILITY CHANGE SAFETY ANALYSIS PAGE 1 0F 4 PROPOSED AMENDMENT NO. 162, REY. 0
, 4 DESCRIPTION:
Proposed Amendment No.162 modifies Technical Specification Section 3.24, Explosive Gas Mixture, and its associated Surveillance Standard, Section 4.28. In Section 3.24, the Proposed Amendment adds an exception to the oxygen ,
limit applicability and changes the' format of the Action Statement and includes.the sentence "When any part of the Waste Gas System is to be removed from service and/or opened to atmosphere, first ensure that the hydrogen i concentration.is <4% and that all sources of hydrogen have been eliminated.
The oxygen concentration limit is not applicable when the system is drained, purged, isolated and in an out-of-service condition." Additionally, the !
following paragraph is added to the Bases:
"The requirements of this specification are not violated when the Waste Gas Holdup" System is drained, purged, isolated, and in an out-of-service condition.
The following paragraph is added to the Surveillance Requirements of Section 4.28:
" Sampling during cold shutdown shall not be required when the Waste Gas Holdup System is drained, purged, isolated, and in an out-of-service condition. "
REASON FOR CHANGE:
Purpose The present Applicability statement of Technical Specification 3.24, Explosive Gas Mixture, requires tTe concentration of oxygen in the Waste Gas Holdup System to be less than or equal to 4% at all times, and if exceeded, the concentration of oxygen is to be reduced to less than or equal to 4% within 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br />. Section 4.28 requires continuous monitoring of the waste gases in the Waste Gas Holdup System. These requirements are not practical or relevant for the conditions when the Waste Gas Holdup System has been drained, purged, isolated, is in an out-of-service condition, or is open to atmosphere.
This proposed amendment clarifies the requirements for operability and sampling of the Waste Gas Holdup System to allow for maintenance or other periods when the system is drained, purged, isolated, and in an out-of-service condition.
EVALDA ION AND BASIS FOR SAFETY FINDINGS:
Sydtems, Subsystems,ComponentsAffected hroposed Amendment No.162 affects the Waste Gas Holdup System.
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ATTACHMENT II (Cont.)
FACILITY CHANGE SAFETY ANALYSIS- PAGE 2 0F 4 PROPOSED AMENDMENT NO. 162, REY. 0
' Safety Functions of Affected Systems / Components Equipment and piping of the Waste Gas Holdup System are all housed within seismic Class I structures. The Waste Gas Holdup System is not a safety-related system. All major components of the system that could present l a radiation hazard to plant personnel are contained within rooms that are i separated by concrete walls (USAR Section 11.1.3, Radioactive Gas Waste Disposal System).
The Waste Gas Holdup System safely collects, stores, and disposes of gases that evolve from primary coolant in all tanks or other equipment where this might occur. The Waste Gas Holdup System is divided into two subsystems, one to handle high activity waste gases and the other to handle low activity gases (USAR Section 11.3.1, System Function).
Gas streams containing primarily hydrogen gas are processed separately from streams containing air gas. Those systems containing hydrogen gas are directed to the Waste Gas Surge Tank. (USAR Section 11.1.3.1.3, Hydrogen Gas Mixtures)
Effects on Safety Functions The objective of monitoring the oxygen concentration in the Waste Gas Holdup System is to ensure that the concentration of potentially explosive gas mixtures contained in the Waste Gas Holdup System is maintained below the flammability limits of hydrogen and oxygen to prevent an explosion. This also helps ensure the integrity of the Waste Gas Holdup System and that the release of. radioactive materials will be controlled in conformance with the requirements of General Design Criterion 60 of 10 CFR 50, Appendix A.
The lower limit of flammability for hydrogen and for oxygen is approximately 5% by volume (Bureau of Mines, Bulletin 503). If the concentration of either gas is kept below this limit, the other gas may be present in higher amounts without danger of producing an explosive mixture. The proposed amendment requires the oxygen concentration of the Waste Gas Holdup System to be less than or equal to 4% unless all sources of hydrogen have been eliminated, and any existing hydrogen reduced to less than a 4% concentration. This allows for opening the system to atmos)here, (after draining, purging, and isolating the system) which would cause t1e oxygen concentration to be greater than 4%.
A District letter to the NRC, dated March 11, 1982, contained an attachment which explained the District's use of a 4% oxygen concentration limit, instead of the 2% limit specified in the standard Radiological Effluent Technical Specifications. The letter and the appropriate section of the attachment are included in this safety analysis.
Additionally, the relaxation of the oxygen sampling requirements in Section 4.28 is only allowed when the system is drained, purged, isolated, and in an out-of-service condition.
r ATTACHMENT II (Cont.)
FACILITY CHANGE SAFETY ANALYSIS PAGE 3 0F 4 PROPOSED AMENDMENT NO.162, REY. 0 Effects on Safety Functions (Cont.)
Therefore, adaptation of' Proposed Amendment No.162 will not affect the
. function of the Waste Gas Holdup System or the safety function of any safety system.
Analysis of Effects on Safety Functions q This proposed revision to Technical Specification Sections 3.24 and 4.28 is 1 part of the corrective action for Licensee Event Report 87-018, dated March 11,1987 (attached). This LER was generated because of the failure to continuously monitor the oxygen concentration in the Waste Gas Holdup System when the system was out-of-service. The system had been taken out-of-service for planned maintenance and had been sampled, drained, purged,and opened to atmosphere.
The present Technical Specification Section 3.24 does not provide for those times when the system is isolated for maintenance and may be open to atmosphere. During these periods, it is not possible to maintain oxygen levels below 4%. Proaosed Amendment No.162 allows oxygen levels in the system to exceed 4%, out only when all sources of hydrogen We eliminated and existing hydrogen concentrations are reduced to (or are determined to be) less than or equal to 4%.
Proposed Amendment No.162 does not require sampling of the Waste Gas Holdup System during cold shutdown when the system has been drained, purged, isolated, and in an out-of-service condition. This reflects the fact that the creation of a flammable mixture of oxygen and hydrogen is not operationally possible when the Waste Gas Holdup System is drained, purged, and isolated.
The changes to Technical Specifications in Proposed Amendment No.162 meet the Bases of the present Technical Specification Section 3.24 "...to ensure that the concentration of potentially explosive gas mixtures contained in the waste gas treatment system is maintained below the flammability limits of hydrogen i and oxygen."
Summary Proposed Amendment No.162 to Rancho Seco Technical Specifications modifies Technical Specification Section 3.24, Explosive Gas Mixture and its associated Surveillance Standard, Section 4.28. In Section 3.24, the Proposed Amendment changes the Action Statement and includes a paragraph which modifies the applicability of the requirements when the Waste Gas Holdup System is drained, isolated, and out-of-service. A paragraph is also added to the Surveillance Requirements which modifies Section 4.28 in the same manner.
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l ATTACHMENT II (Cont.) !
FACILITY CHANGE SAFETY ANALYSIS PAGE 4 0F 4 PROPOSED AMENDMENT NO. 162, REY. O Summary (Cont. )
The Technical Specification changes included in the Proposed Amendment do not circumvent the requirements to maintain a non-flammable atmosphere in the Waste Gas Holdup System. The changes do reflect the fact that a flammable
. mixture of hydrogen and oxygen is precluded when the system is drained, purged, and isolated.
Proposed Amendment No.162 does not change the facility as described in the USAR. The changes do not affect the functicn of the Waste Gas Holdup System, nor do they affect the safety function or any safety system. No failure modes are introduced by the changes since the requirements are changed only when the system has been removed from service, isolated, drained, or purged. The changes do not involve " Major Changes to Radioactive Waste Treatment Systems" as defined in Technical Specification Section 6.17.3.B.
The probability of occurrence or the consequences of an accident or malfunction of equipment important to safety previously evaluated in the safety analysis report will not be increased since the changes only affect the Waste Gas Holdup System once the system has been removed from service and isolated from any source of hydrogen gas.
The possibility for an accident of malfunction of a different type than any evaluated previously in the safety analysis report will not be created since any explosive concentrations of hydrogen gas are purged from the system and sources of hydrogen are isolated prior to the system being taken out-of-service and opened to the atmosphere.
The margin of safety, as defined in the basis for any Technical Specification, is not reduced since the possibility of the formation of a flamable mixture of hydrogen and oxygen is precluded by the proposed amendment; present Technical Specification Bases are met.
Therefore, Proposed Amendment No.162 does not involve an Unreviewed Safety Ques tion.
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ATTACHMENT III- PAGE 1 0F 1 NO SIGNIFICANT HAZARDS. CONSIDERATION Proposed Amendment No.162 modifies the technical specifications on oxygen and hydrogen concentrations in the Haste Gas Holdup System to provide for
, periods in which the system is drained, purged, isolated and in an out-of-service condition, and/or open to the atmosphere. Additiont.11y, the name, Haste Gas Holdup System, is capitalized wherever presently uncapitalized. This latter change is proposed to make the system's name consistent throughout the specifications.
Presently, the technical specifications require that the concentration of oxygen in the Haste Gas Holdup System be limited to not more than four percent. This limitation ensures that the concentration of potentially explosive gas mixtures contained in the Haste Gas Holdup System is below the flammability limits of oxygen and hydrogen. However, the existing specifications do not provide for when the Haste Gas Holdup System is free of potentially explosive gas mixtures as, for example, when the system is open to the atmosphere for maintenance. The proposed changes to'the technical specification provide for such non-operational conditions, and make the system name consistent throughout the applicable specifications.
The District has reviewed the proposed changes against each of the criterion of 10 CFR 50.92 and concluded that the changes to the Technical Specifications to provide for the non-operational con'jitions discussed above would not:
- a. involve a significant increase in the probability or consequences of an accident previously evaluated because the proposed changes simply provide for the non-operational conditions during which a potentially explosive gas mixture in the Haste Gas Holdup System is precluded, or
- b. create the possibility of a new or different kind of accident from any previously analyzed because the proposed changes simply provide for the non-operational condition-during which the Haste Gas Holdup-System is free of any potentially explosive gas mixtures. There are no changes to the design or operation of the plant, thus no possibility of a different of new kind of accident is introduced.
- c. Or involve a significant reduction in a margin of safety because no design or operational changes are proposed.
The proposed capitalizing of the system name, Haste Gas Holdup System, is purely administrative, and thus has no involvement with any accident concerns er margins of safety.
On the basis of the above, the District concludes that the proposed changes do not constitute any significant hazards to the public, and in i no way endanger the public's health and safety.
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