3F0198-28, Clarifies Util Implementation of Statement Re Method for Determining Content of Waste Gas Decay Tanks at Plant,Unit 3.Surveillance Procedure SP-730, Explosive Gas & Storage Tank Monitoring Chemistry Surveillance Program, Encl

Clarifies Util Implementation of Statement Re Method for Determining Content of Waste Gas Decay Tanks at Plant,Unit 3.Surveillance Procedure SP-730, Explosive Gas & Storage Tank Monitoring Chemistry Surveillance Program, Encl

ML20199G696
Person / Time
Site:	Crystal River
Issue date:	01/30/1998
From:	Pardee C FLORIDA POWER CORP.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20199G701	List: 3F0198-28, Clarifies Util Implementation of Statement Re Method for Determining Content of Waste Gas Decay Tanks at Plant,Unit 3.Surveillance Procedure SP-730, Explosive Gas & Storage Tank Monitoring Chemistry Surveillance Program, Encl ML20199G714
References
3F0198-28, 3F198-28, NUDOCS 9802040327
Download: ML20199G696 (4)

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??.7 m W EId.Q E. L . m n January 30,1998 3F0198 28 U.S. Nuclear Regulatory Conunission Attention: Document Control Desk Washington, DC 20555-0001

Subject:

Clarification of Compliance With NRC Safety Esaluation Report Technical Evaluation Report Regarding W- , Gas Decay Tank Surveillance

References:

1. NRC to FPC letter,3 Nil 97 21, dated November 24,1997

2. FPC to NRC letter,3F1297 20, dated Decemler 17,1997

3. NRC to FPC letter,3N0684 32, dated June 27, 1984

Dear Sir:

The purpose of this letter is to clarify Florida Power Corporation's (FPC) implementation of a statement regarding the method for determining the content of the waste gas decay tanks (WGDT) at Crystal River Unit 3 (CR-3). The statement was made in the NRC Safety Evaluation Report (SER) Technical Evaluation Report (TER) that accompanied Amendment No. 69 to CR 3's operating license (Reference 3). This issue was the subject of Violation 50-302/97-16-05 in which the NRC cited FPC for not determining the quantity of radioactive material in each WGDT as specified by the Offsite Dose Calculation h1anual (ODCht) Surveillance Requirement 2.17.1 (Reference 1), in the response to the violation (Reference 2), FPC committed to submit a letter to the NRC clarifying FPC's impicmentation of the NRC TER statement related to sampling each WGDT.

i l Hackground The CR-3 Offsite Dose Calculation hianual (ODCht) Section 2.17 specifies that the o.uantity of radioactivity contained in each WGDT shall be limited to less than or equal to 39,000 curies (considered as Xenon-133). ODChi Surveillance Requirement 2.17.1 requires that the quantity of radioactive material contained in each WGDT shall be determined to le within the limit at least once per seven days whenever radioactive materials are being added to the tank, and at least once

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per 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> during prhaary coolant system degassing operations, godl WB-Violation 50-302/97-16-05, cited in NRC Inspection Report 50-302/97-16 (Reference 1), stated that yg, the quantity of radioactive material in each V'GDT was not being determined as specified by g 1 ODChi Surveillance Requirement 2.17.1. This requirement of the CR-3 license was added by Amendment No. 69, dated June 27,1984 (Reference 3). The Safety Evaluation accompanying the y{Fi amendment had, as supporting information, a Technical Evaluation Report (TER) prepared by EG&G Idaho, of Idaho National Engineering Laboratory, entitled, " Radiological Effluent Technical g

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>', U.S. Nuclear Regulatory Commission 3F0198 28 Page 2 of 3 Specifications (RETS) Implementation Crystal River Unit No. 3 Nuclear Generating Plant."

Section 3.2.5 of that TER, entitled, " Tank inventory Limits," discuucs that the quantity of radioactive material in each WGDT is limited to less than or equal to 39,000 euries (Xenon 133 equivalent), which is less than the value corresponding to 0.5 rem at the exclusion area boundary.

The TER states that surveillance on the WGDTs will be perfonned once per 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> during degassing periods and weekly at other times.

System Description and Operation The Waste Gas Decay Tanks are the holdup tanks for the gaseous radioactive waste generated by the plant. There are three WGDTs in the CR 3 Gas Waste Disposa! System (GWDS) which together provide for storage of gases prior to release to the atmosphere. Only one of these WGDTs is in service at any one time. One WGDT is dedicated to only receive gases vented from the RCS/htakeup Tank (h1UT). This is due to the high hydrogen concentration and radioactive gases generated in the h1UT. The other two tanks are rotated as the inservice tank for the balance of the plant inputs to the GWDS. The tank designated as " inservice" is the WGDT that is aligned to one of the two waste gas compressors. These compressors take suction from a waste gas header which receives inputs of waste gases from numerous primary support system tanks. The compressors pump the header to a WGDT whenever a pressure of greater than 2 psig exists in the header, thus maintaining a relatively constant gas header system overpressure.

The inservice WGDT is pressurized to approximate 5 75 psig and isolated to allow for decay of the gases. The other WGDT is then placed in service on the header by being connected to one of the compressors. The full WGDT remains isolated until it is needed for gas storage. At that time s it is sampled, analyzed, and released to the environment. This tank is then placed in service and the other tank isolated to allow for decay.

The one tank segregated for RCS/h1UT venting will contain the highest quantity of radioactive gases. It is in service only for short durations during venting operations, typically approximately 45 minutes. This allows the tank to decay for long periods of time because of the time needed to fill the tank. This process keeps the bulk of the offgassed hydrogen confined to this tank, thereby preventing mixing with oxygen in the waste gas header and thus creating an explosive gas mixture.

Additional discussion of the Radioactive Gas Waste Disposal System at CR-3 is provided in Section 11.2.2 of the Final Safety Analysis Report (FSAR). Figure 11-3 of the FSAR is a detailed flow diagram depicting this system.

Clatification Section 3.2.5 of the TER states that surveillance on the WGDTs veill te performed once per 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> during degassing periods and weekly at other times. The NRC inspector has interpreted this to mean that direct sampling of the tanks was the method used to determine the inventory of radioactive material in each WGDT. The process used by FPC since 1981, prior to the issue of the TER, has been an indirect method of determining the curie conteat in the WGDTs. The method used involves sampling the hiake-Up Tank (h1UT-1) gas space followed by performing a gas gamma analysis to determine Xenon 133 equivalence rather than direct sampling of each of the

U.S. Nucicar Regulatory Commission 3F0198-28 Page 3 of 3 three WGDTs. The gases in the MUT comprise the most concentrated radioactive material addition to the WGDTs. The inventory in the WGDTs can le determined to remain below the Xenon 133 equivalence of 39,000 curies if the makeup tank concentration remains within the acceptable range of :s; 122 microcuries per cubic centimeter (pCi/cc). This sampling and analysis of MUT-1 gas space is performed by Surveillance Procedure (SP) $P-730,

• Explosive Gas and Storage Tank Monitoring Chemistry Surveillance Program.* A copy of SP 730 Revision 20, is provided as Attachment A. This indirect method was established for the reasons explained below.

The design of the system for sampling of the WGDTs would require purging the tank to be sampled for a specified period of time to the inservice tank in order to obtain a representative sample. Sampling of the WGDTs in this manner could result in the introduction of oxygen into the system by means of air inleakage into the system during maintenance and through vacuum breakers and loop seals. This oxygen, in combination with the hydrogen, would create an explosive gas atmosphere. This process would also result in mixing of the contents of the WGDTs. This mixing of tank contents also has the potential for creating an explosive gas atmosphere in the WGDTs by mixing of a tank with high hydrogen level with another tank containing oxygen. Creating such an explosive gas atmosphere in either manner could result in entry into ODCM Section 2.18 which requires an immediate purge of the WGDT, with the explosive gas mixture, to the enviromnent. Performing this immediate purge would reduce the decay time of the radioactive gases in the tanks. This reduced decay time could result in an increase in the offsite doses to the public. To preclude creating this explosive atmosphere, the indirect method of determining the curie content of the WGDTs described above was developed.

FPC revised the ODCM to clarify the meaning of determining the quantity of radioactive material in each WGDT. This ODCM revision was made pursuant to 10CFR50.59 as supported by a Safety As:.essment/Unreviewed Safety Question Determination prepaied by FPC. The clarification was addition of a footnote to Section 2.17, which states: " Determining that each WGDT is in compliance with the limit may be done by a method other than direct sampling of the tank provided it is in accordance whh an approved procedure." Sp-730 represents the approved procedure.

Excerpts from the ODCM reflecting the revisions are provided as Attachment B.

There are no new commitments in this letter. If you have any questions concerning this issue, please contact Mr. David Kunsemiller, Manager, Nuclear Licensing at (352) 563-4566.

Sincerely, i

Y C. G. Pardee Director Nuclear Plant Operations CGP/rer Attachments xc: Regional Administrator, Region 11 Senior Resident inspector NRR Project Manage.

ATTACHMENT A SURVEILLANCE PROCEDURE SP-730, REV. 20

" EXPLOSIVE GAS AND STORAGE TANK MONITORING CHEMISTRY SURVEILLANCE PROGRAM"

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