ML20212E364

Application for Amend to License DPR-54,revising Tech Specs 3.1.6, Leakage Bases & 3.8, Fuel Loading & Refueling to Reflect Replacement of Existing Radiation Monitors R-15001 a Through E W/Radiation Monitors R-15100 & R-15044.Fee Paid

ML20212E364
Person / Time
Site:	Rancho Seco
Issue date:	02/20/1987
From:	Julie Ward SACRAMENTO MUNICIPAL UTILITY DISTRICT
To:	Miraglia F Office of Nuclear Reactor Regulation
Shared Package
ML20212E368	List: ML20212E364 ML20212E407
References
JEW-87-094, JEW-87-94, TAC-64879, NUDOCS 8703040335
Download: ML20212E364 (10)

Text

$suun SACMAMENTO MUNICIPAL UTILITY DISTRICT I1 P. O. Don 15830. Gactam.mto CA 05052 1830,1010) 452 3211 AN EL ECiltlC SYSTEM SiitVING illE FIEAlli OF CALIFOltNIA l

) February 20, 1987 JEW 07-094 Director of Nuclear Reactor Regulation Attn: Frank J. Miraglia, Jr.

Division of PWR Licensing-B U. S. Nuclear Regulatory Conuntssion Washington, D. C. 20555 Docket No. 50-312 Rancho Seco Nuclear Generating Station Unit No. I t.icense No. OPR-54 PROPOSED AMEN 0 MENT 156

Dear Mr. Miraglia:

In accordance with 10 CIR 50.90, the Sacramento Municipal Utility District proposes to amend its Operating License DPR-54 for Rancho Seco Nuclear Generating Station, Unit 1.

Proposed Amendment No. 156 consists of revisions to the Technical Specifications 3.1.6, "Leakago" Dases and 3.0, " fuel Loading and Hofueling" to reflect the replacement of the existing radiation monitors R-15001 A through E with radiation monitors R-15100 and R-15044. Also the Technical Spectf1 cation 3.1.6 Dases is being updated to state that the particulato channel (l.c., new radiation monitor R-15l00) is the only radiation sensitive reactor coolant leak detection method.

These changes are discussed in detail in [nclosure I which is the description of the proposed changes, the associated technical evaluatton of the chango, and the "No Signif1 cant llazards Determination." Enclosure 2 15 the proposed Technical Specifications.

Pursuant to 10 CIR $0.91(b),(1), the Radiological llcalth Branch of liio California Stato Department of ilcalth Services has been informed of this proposed amendinent by toalled copy of this submittal.

Inclosed is a check f or $150.00 as required by 10 CFR 110.21

" Statement of fees."

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itANCit0 BtCO NUCLr Aft Of NtnAflNG 87Afl0N ' 14440 f eti Cities flomi, lietekt. C A Or;038 9109, (2001333 2935

o Frank J. Miraglia, Jr. February 1987 JEW 87-094 If you have any questions concerning this submittal, please contact Mr. Non Colombo at the Rancho Seco Nuclear Generating Station.

Sincerely, e1 Wl J r eputy General Manager, Nuclear Sworn to and subscribed before me this hh day at February, 1981.

Nhon 9Yuubnc Notary Public I d

Attachments - 2 ]^^$

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ENCLOSURE 1

o i DESCRIPTION Of PROPOSED CHANGES:

^

Proposed Amendment #156 consists of changes to the Bases of Technical .

Specification 3.1.6 and an editorial change to Technical Specification 3.8.10. Technical Specification 3.1.6 Bases are updated to accurately reflect RCS leak detection by the radioactivity-based method during normal operation without continuous Reactor Building (R8) purge. Technical Specification .

3.8.10 is modified to remove the specific references to Radiation Monitors R-15001A and R-160018, which will be' replaced.

TECHNICAL EVALUA110N:

Systems. Subsystems and Components / Safety functions Af fected 10 CFR 50, Appendix A, GDC 30, Quality of Reactor Coolant Pressure Boundary, requires that, "means shall be provided for detecting and, to the extent practical, identifying the location of the source of reactor coolant leakage." In response, USAR Section 1.5.26 notes "the means provided for RCS leak detection and identification are outlined in Section 4.2.3.7." RCS Leak Detection is based on three separate and diverse methods: A) Sump level, 8)"

Radioactivity, and C) RCS inventory calculation (USAR 4.2.3.7 Technical Specification 3.1.6),

fundamentally, the RCS leak detection system has the safety function of preventing Loss of Coolant Accidents by early detection and warning. As amplified by the Bases of Technical Specification 3.1.6, "every reasonable effort will be made to reduce reactor coolant leakage including evaporative losses to the lowest possible rate and at least below I gpm in order to prevent a large leak from masking the presence of a smaller one. It must be recognized that leaks on the order of drops per minute through any of the walls of the primary system could be indicative of materials failure such as by stress corrosion cracking." The failure of the RCS leak detection system to perform its safety function when needed (i.e., to provide early warning of a condition which could lead to a LOCA) is mitigated by the proper functioning of the Emergency Core Cooling System (see USAR Chapter 14.2.2.5).

New monitor R-15100 provides the RCS leak detection method based on radioactivity. Radiation monitor R-15100 is installed to replace existing monitor R-15001 for RCS leak detection. R-15100 includes Particulate Iodine and Gas Monitor Channels. OPERA 81LliY of R-15100 for RCS leak detection is based on the Particulate monitor, not the lodine or Gas monitors. R-15100 is able to detect approximately a 1 gpm RCS leak in about an hour. The Bases of Technical Specification 3.1.6 and USAR Section 4.2.3.7 are being revised to accurately reflect this response time.

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5,vitems. Subsystems and Components / Safety Functions Affected (Continued)

Contrary to Technical Specification 3.1.6 Bases and USAR Section 4.2.3.7, the existing gaseous radiation monitor can not detect a 1 gpm RCS leak, with 1%

defective fuel, in 67 seconds (documented in LER 87-09, dated February 9, 1987). Recent analysis has demonstrated that, by .its nature, a noble gas monitor-will be much less sensitive than an air particulate monitor. The background air particulate activity in the reactor building is maintained at a. reduced level as a result of continuous filtering and plateout. A similar removal mechanism does not exist and can not be employed

-for radioactive gases in the RB atmosphere because R8 purging is no longer permitted (see Technical Specification 3.6.7). As an example, during plant operation with no Reactor Building purge, the in-containment noble. gas background concentration quickly reaches an equilibrium level whose magnitude would significantly mask the airborne concentration that would result from an RCS leak approaching 100 gpm. The Iodine channel is ineffective for similar reasons.

Response time of the R-15100 particulate monitor for RCS leak detection is dependent upon the background particulate activity level. If this background level exceeds its expected range, R-15100's response time to RCS leakage will be substantially longer due to detector overloading. Possible causes of high R3 equilibrium level include: 1) extraordinarily high failed fuel (greater than 0.1%), 2) extraordinarily high identified RCS leakage, and 3) failure of the RB HVAC recirculation fans or filters. Daily reading of strip chart ,

recorder RJR-150000, located on the H3TMI cabinet, ensures that the detector does not become unknowingly overloaded and inoperable.

Operating procedures will be written / revised to provide the operators with an understanding of the 3 variables and the technical material necessary to adequately respond to annunciators and determine the appropriateness of the alarm setpoints. These procedures will be controlled under 10 CFR 50.59.

The alert alarm setpoint will be maintained at about three times the highest expected background level with the confirmatory high alarm setpoint at about one order of magnitude above the highest expected background levels. These setpoints ensure timely alarm indication to abnormal leakage without spurious alarm actuation. The initial setpoints for R-15100 are based on a thorough review of historical and calculated conditions. Further, these setpoints

shall be adjusted appropriately, after further operating experience is obtained.

Present Technical Specification 3.8.10 requires the RB Purge System,

" including the radiation monitors, R-15001A and R-15001B," to be tested and verified operable immediate'ly prior to refueling. This Radiation Monitoring System safety function of R-15001 will be performed by radiation monitor R-15044. References to specific radiation monitors are not necessary and are being deleted from Technical Specification 3.8.10. This is an editorial change only.

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Analysis of Effects

-The calculated radiation detector response time to a 1 gpm RCS leak given in the Technical Specification 3.1.6 Bases has been non-conservative for cases without continuous RB purging. While the NRC has reviewed normal operation without RB purge, there is no indication that the implications of non-purging-operation on RCS leak detection had been considered (see NRC SER on License Amendment #49, August 3, 1983). Contrary to the present Technical Specification 3.1.6 Bases, the District has not had and will not have a gaseous radiation detection method which can detect a 1 gpm leak in less than an hour. Contrary to the present lechnical Specification 3.1.6 Bases, the District will not have a radiation-sensitive detection method which can detact a 1 gpm leak in 67 seconds (1% failed fuel) or 5.3 minutes (0.1% failed fuel). Technical Specification 3.1.6 Bases state that Reactor Building area radiation monitors can indicate increases in RCS leakage. These RB area monitors, like the existing gaseous monitor, can provide only a very qualitative indication of RCS leakage and it is inappropriate to take credit ,

for their leak detection capability. Also contrary to the present Technical Specification 3.1.6 Bases, the District will not have the capability to perform a " quick evaluation...over a short period of time (e.g., 5 minutes)",

with the particulata monitor to verify RCS leakage indicated by another means. The present Technical Specification 3.1.6 Bases do accurately reflect the response time of the newly installed particulate monitor R-15100A at "about 1 to 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />."

To support the installation of R-15100, the basis for the radioactivity-sensitive RCS leak detection method during normal operation (without RB purging) was prepared for the first time. The design criterion specified for R-15100 is that it shall be able to detect approximately 1 gpm of. unidentified Reactor Coolant System leakage into the RB in approximately 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> and alert the Control Room operators. This radioactivity-based leak detection method is qualitative only. To provide a quantitative estimate of leak rate requires a calculation involving actual plant conditions (including RCS activity, RB equilibrium concentration, and detector sensitivity). In addition, an RCS leak qualitatively indicated by the radioactivity-based method must be confirmed by other means, such as RCS inventory calculation or sump level indication.

Although the Bases of Technical Specification 3.1.6 are being updated, the integrity and adequacy of the RCS leak detection system for accomplishing its -

safety function is maintained. Three separate and diverse methods are provided: A) Sump level, B) Radioactivity (airborne particulate), and C) RCS Inventory. Each method has distinct advantages and applicability. The sump level method (drain accumulator tank dumping frequency) is quantitative, but is sensitive to all leakage inside the Reactor Building, not just RCS leakage. The radioactivity-based method is continuous but not quantitative.

The RCS inventory method is quantitative but not continuous. Indication of small abnornel RCS leakage by any one method requires further investigation.

Upon confirmation'that a leak indeed exists, appropriate operator action is undertaken. Gross RCS leakage can be verified by plant status indicators including Makeup flow Rate, Makeup Tank Level, and Pressurizer level. By amploying all available indications, it can be assured that abnormal leakage will be detected and investigated in a timely manner.

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-Analysis of Effects-- (Continued)

Reg. Guide 1.45, Position 3, requires three separate detection methods based on: 1) sump level, 2) airborne particulate radioactivity, and 3) either air cooler condensate flow rate, or airborne gaseous radioactivity. Although not committed to Reg. Guide 1.45, the District provides the first two methods and substitutes a RCS Inventory-based method for the third. These three methods 4 (sump level, radioactivity, and RCS inventory) have previously been accepted by the NRC (

Reference:

Technical Specification 3.1.6 Bases).

Reg. Guide 1.45, Position 5, requires each detection method "to be adequate to

+ detect a leakage rate, or its equivalent, of one gpm in less than one hour."

Although not committed to Reg. Guide 1.45, the District meets.the intent of this with the particulate and sump level-methods', by detecting a 1 gpm leak in 1-2 hours. This time of leak detection is considered safe and adequate. The RCS Inventory method is not a continuous method but can confirm a 1 gpm leak in one hour if the leak is detected by other means. Also this approach is consistent with NRC staff positions with other Reactor Licensees.

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Basis for No Sianificant Hazards Determination The proposed change does not involve a significant hazards consideration because operation of Rancho Seco in accordance with this change would not:

(1) involve a significant increase in the probability or consequence of an accident previously evaluated. The bases of Technical Specification 3.1.6

" Leakage" are being updated to state that the only radiation-sensitive leak detection methods will be a particulate channel (i.e., a new Radiation Monitor R-15100). The new Radiation Monitor R-15100 is essentially an. equivalent replacement of the existing monitors R-15001 A l through E. .The reactor coolant leak detection response times for the radioactivity based method as described in Technical Specification 3.1.6 Bases have been non-conservative whenever the Reactor Building radioactivity background builds up during non-purging conditions. Also the gaseous and area radiation monitors are either not suitable or are too

insensitive f or leak detection. The new Radiation Monitor particulate channel R-15100 has the ability to detect a small unidentified leak of approximately 1 gpm in approximately one hour. This response time is in general agreement with the requirements of Regulatory Guide 1.45 " Reactor Coolant Pressure Boundary Leakage Detection Systems". This is a qualitative leak detection method and the actual leakage rate can be determined from one of the other two leak detection systems (i.e., sump level indication and Reactor Coolant inventory calculation). . Although the Bases of Technical Specification 3.1.6 are being updated, the integrity and adequacy of the Reactor Coolant Leak Detection System for accomplishing.its safety function is maintained. Both the probability and consequences of small and large break LOCAs have been analyzed in the USAR and' detection systems can not increase the propensity for a LOCA nor its

consequences.

1 Also Technical Specification 3.8.10 is revised to remove the specific references to radiation monitor R-15001 A and B. This monitor has been replaced by radiation monitor R-15044 which is essentially an equivalent replacement. .Thus, the Technical Specification revision is editorial in nature.

Therefore, this revision does not significantly ircrease the probability or consequences of an accident.

(2) create the possibility of a new or different kind of accident from any previously analyzed. The new Radiation Monitors R-15001 and R-15044 are essentially an equivalent replacement of the existing monitors R-15001 A through E. No changes of safety functions have been identified and no new failure modes have been identified. Therefore, the revision does not create the possibility of a new or different kind of accident.

(3) involve a significant reduction in a margin of. safety. The'new Radiation Monitor-R-15100 is essentially an equivalent replacement of the existing >

monitors R-15001 A through E. The reactor coolant leak detection response times for.the radioactivity based method as described in Technical Specification 3.1.6 bases have been non-conservative whenever the Reactor Building radioactivity background builds up during non-purging conditions. It should be noted that it is a safety enhancement to limit containment purging during operation, thereby. increasing the. decay of fission product and reducing an potential releases to the public from the containnent. This safety enhancement increases the margin of. safety afforded the public and offsets any apparent decrease in the margin of safety brought about as a result of the increase in detection time associated with the new Technical Specification. Also the gaseous and

, area radiation monitors are not genuinely suited for leak detection. lhe new radiation monitor particulate channel R-15100 has the ability to detect a scall unidentified leak of 1 gpm in approximately one hour. This response time is consistent with.the requirements of Regulatory Guide 1.45. 1This is a qualitative leak detection method and the actual leakage rate can be determined from one of the other two leak detection systems (i.e., sump level indication and Reactor Coolant inventory calculation).

Although the bases of Technical Specification are being updated to reflect the present design, the integrity and adequacy of the reactor coolant leak detection system for accomplishing its safety function is maintained.

Also Technical Specification 3.8.10 is revised to remove the specific references to Radiation Monitor R-15001 A and B. This monitor has been replaced by Radiation Monitor R-15044 which is essentially an equivalent replacement. Thus, the. Technical specification revision is editorial in nature.

Therefore, this revision does not involve a significant reduction in a margin of. safety.

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,e ENCLOSURE 2 PROPOSED TECHNICAL SPECIFICATION AMENDMENT NO. 156

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