ML20212G135

Advises That Changes to Radiological Effluent Tech Specs Should Be Proposed to Eliminate Possibility of Unacceptable Radiation Levels in Liquid Effluents.Evaluation of 860224 Rept Encl.Meeting Requested

ML20212G135
Person / Time
Site:	Rancho Seco
Issue date:	07/22/1986
From:	Stolz J Office of Nuclear Reactor Regulation
To:	Julie Ward SACRAMENTO MUNICIPAL UTILITY DISTRICT
References
TAC-64735, TAC-64736, NUDOCS 8608130449
Download: ML20212G135 (12)

Text

' t July 22,1896 Docket No. 50-312 Mr. John E. Ward Assistant General fianager, Nuclear -

Sacramento Municipal Utility District 6201 S Street P. O. Box 15830 Sacramento, California 95813

Dear Mr. Ward:

As stated in my letter of April 28, 1986, the NRC staff has been reviewing the Rancho Seco Radiological Effluent Technical Specifications (RETS). To date, this review has been limited to pertinent aspects of the requirements for effluent monitoring, nearby land use identification, offsite dose calculations, environmental monitoring, and limitations on calculated offsite doses. This review includes the Rancho Seco Offsite Dose Calculation Manual (0DCM), and addresses the degree to which compliance with this document, along with the RETS, provides assurance of meeting the requirements of 10 CFR Part 50, Appendix I, and 40 CFR Part 190 concerning radiation doses received by members of the public.

The above review was undertaken because of the conclusions of the February 24, 1986 document, "NRC Assessment of the Environmental Radioactive Contamination in the Vicinity _ of the Rancho Seco Nuclear Power Plant," a copy of which was transmitted to you by my April 28, 1986 letter. The above assessment noted that radionuclide concentrations near the Rancho Seco site resulting from the release of liquid effluents from the plant were found to be at levels which

, could cause maximun-exposed individuals to receive potential doses well in excess of the RETS dose limits based on the regulations cited. This brings to question whether the Rancho Seco RETS and ODCM provide adequate assurance that the requirements of the regulations are being met.

Specifically, as a result of the NRC Staff's review undertaken in connection with contamination found in the vicinity of the Rancho Seco Plant, the NRC staff found that there is an inconsistency between the Lower Limit of Detection (LLD) as listed in Table 4.21-1 of the Technical Specification Surveillance Standards (Section 4.21.1) and the Technical Specification sections (3.17.2 and 4.21.2) relating to 10 CFR Part 50, Appendix I design objectives. Because of the highly atypical characteristics of the cooling water system and of the receiving waters, liquid effluent releases at the i present LLD values, if properly calculated, can result in doses in excess of Part 50 Appendix I and the limits specified in 40 CFR 190.

To correct this situation and to assure that offsite releases are in accordance with applicable Federal Regulations, you should propose appropriate changes

! to the Rancho Seco Technical Specifications, l

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4 Mr. John E. Ward After consideration of our enclosed evaluation, we suggest that a' meeting or conference call be held with the staff to discuss your future plans for.

dealing with the concerns indicated and for assuring continued compliance

- with the regulations.

Sin,cerely,

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Jout 2, syg. g ;,

John F. Stolz, Director PWR Project Directorate #6 Division of PWR Licensing-B

Enclosure:

As Stated cc w/ enclosure:

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Mr. John E. Ward the dose limits, atypically greater levels of accuracy or conservatism are generally needed in quantifying liquid effluent releases, identifying nearby land uses, and calculating offsite doses at Rancho Seco than are reflected in the Rancho Seco RETS and ODCM which assume more typical plant designs and sites.

A specific finding in this regard is the identification of an error in that the model RETS lower limit of detection (LLD) values are provided in the Rancho Seco technical specification surveillance requirements for liquid effluents.

The use of these LLD values can result in releases of radioactive materials to which offsite doses may be attributed at Rancho Seco that are in excess of the limits of the RETS to implement the regulations (10 CFR 50, Appendix I, and 40 CFR 190). Therefore, you should propose the appropriate change to the technical specifications in order to correct this situation. Further, after consideration of our enclosed evaluation, we suggest that a meeting or conference call be held with the staff to discuss your future plans for dealing with the concerns indicated and for assuring continued compliance with the regulations as i:1ple-mented through RETS.

4 John F. Stolz, Director PWR Project Directorate #6 Division of PWR Licensing-B

Enclosure:

As Stated cc w/ enclosure:

See next page DISTRIBUTION ACRS-10 SMiner Docket File BGrimes >

NRC PDR JPartlow L PDR GKalman PBD-6 Rdg RIngram FMiraglia Gray File OELD EBrach EJordan H0rnstein 1

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Mr. R. J. Rodriguez Rancho Seco Nuclear Generating Sacramento Municipal Utility District Station cc: -

Mr. David S. Kaplan, Secretary Sacramento County and General Counsel Board of Supervisors Sacramento Municipal Utility 827 7th Street, Room 424 District Sacramento, California 95814 6201 S Street P. O. Box 15830 Ms. Helen Hubbard Sacramento, California 95813 P. O. Box 63 7-- Sunol, California 94586 Thomas Baxter, Esq.

Shaw, Pittman, Potts & Trowbridge 1800 M Street, N.W.

Washington, D.C. 20036 Mr. Ron Columbo Sacramento Municipal Utility District 7 Rancho Seco Nuclear Generating Station 4440 Twin Cities Road Herald, California 95638-9799 Mr. Robert B. Borsum Babcock & Wilcox Nuclear Power Generation Division Suite 220, 7910 Woodmont Avenue Bethesda, Maryland 20814

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Resident Inspector / Rancho Seco c/o V. S. N. R. C.

14410 Twin Cities Road Herald, California 95638 Regional Administrator, Region V U.S. Nuclear Regulatory Commission 1450 Maria Lane, Suite 210 Walnut Creek, California 94596 Director Energy Facilities Siting Division Energy Resources Conservation &

Development Commission 1516 - 9th Street Sacramento, California 95814 Mr. Joseph 0. Ward, Chief Radiological Health Branch State Department of Health Services 714 P Street, Office Building #8 Sacramento, California 95814

e STAFF EVALUATION OF RANCHO SEC0 RADIOLOGICAL EFFLUENT TECHNICAL SPECIFICATIONS AND OFFSITE DOSE CALCULATION MANUAL REGARDING 0FFSITE DOSES FROM LIQUID EFFLUENT Concerns have recently been raised regarding possible unacceptable radiation levels in liquid effluent releases from the Rancho Seco plant. The following is a staff evaluation of these concerns based in part on the conclusions con-tained in the February 24, 1986 document, "NRC Assessment of the Environmental Radioactive Contamination in the Vicinity of the Rancho Seco Nuclear Power Plant." Our evaluation considered the current Rancho Seco Radiological

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Effluent Technical Specifications (RETS) and Offsite Dose Calculation Manual (0DCM) which are intended to assure that doses from liquid effluent releases are within the limits specified in the regulations.

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NUREG-0133, " Preparation of Radiological Effluent Technical Specifications for Nuclear Power Plants," provides calculational models for dose contributions for implementing 10 CFR Part 50, Appendix I "as low as is reasonably achievable" requirements. For liquid effluent releases, a near field average dilution factor is used which takes into account the maximum undiluted liquid waste flow, the combined liquid releases for each unit, and the mixing effects in the receiving water body in the near field of the discharge structure. For plants with non-recirculating main condenser cooling systems, the mixing effects in the receiving water body are ignored for conservatism. However, for plants with recirculating cooling systems, where cooling water discharge flowrates are much less than for plant with non-recirculating cooling systems, credit is allowed for mixing effects in the near field of the receiving water body up to the degree of dilution that would be achieved by a 1000 cubic feet per second flow rate of non-recirculating cooling water.

i Rancho Seco has a recirculating main condenser cooling system. Based on a comparison of Environmental Statements for various nuclear power plants, the Rancho Seco design average discharge flow rate is one of the lowest of all

, U. S. nuclear power plants. As with similar plants, the liquid waste discharge 1

includes condenser cooling and service water system blowdown, and oiher minor streams in addition to liquid radwaste effluents. However, atypically, at Rancho Seco there is little or no dilution of liquid wastes after discharge from the plant discharge structure due to the almost total absence of a receiving water body comprised of water other than from the plant discharge.

Consequently, no credit is provided in the Rancho Seco ODCM for mixing in the receiving water body in the near field of the discharge structure.

The Rancho Seco RETS are patterned after the guidance of NUREG-0472, " Standard

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Radiological Effluent Specifications for Pressurized Water Reactors," which is in turn based on typical reactor plant designs and site characteristics. Both the Rancho Seco RETS and NUREG-0472 incorporate provisions for:

1. Radioactive liquid effluent monitoring instrumentation and sampling to monitor and control the release of radioactive material during actual or potential releases;

2. ~An annual land use c.ensus to ensure that changes in the use of areas at and beyond the site boundary are identified and modifications to the environ-mental monitoring program are made if required by the results of the census;

3. An ODCM to contain the methodology and parameters to be used in the cal-culation of offsite doses due to radioactivity in effluents;

4. An environmental monitoring program which supplements the radiological effluent monitoring program by verifying that the measurable concentrations of radioactive materials and levels of radiation are not higher than expected on the basis of the effluent measurements and the modeling of environmental exposure pathways; and

5. Limitations on calculated doses to members of the public to implement 10 CFR Part 50, Appendix I, and 40 CFR Part 190.

l The Rancho Seco RETS provide for certain radioactive liquid effluent monitoring instrumentation to monitor and control, as applicable, releases of radioactive material during actual or potential releases. Each batch of liquid waste from the waste release tank must be sampled and analyzed prior to release for the principal gamma emitters (Mn-54, Fe-59, Co-58, Co-60, Zn-65, Mo-99, Cs-134, Cs-137, Ce-141 and Ce-144) and I-131; one batch sample per month is analyzed for dissolved and entrained gases (gamma emitters); and monthly or quarterly composites of the batch samples are analyzed for tritium, gross alpha, Sr-89 and Sr-90. A gross radioactivity monitor is required to be operable on the regenerant hold-up tank discharge line.

To comply with the Rancho Seco RETS, the lower limit of detection (LLD) for these radionuclides must be as follows: 5 x 10-7 microcurie per milliliter or better for the principal gamma emitters, 1 x 10-6 microcurie per milliliter or

_ better for I-131, 1 x 10-5 microcurie per milliliter or better for dissolved and entrained gases and for tritium,1 x 10-7 microcurie per milliliter or better for gross alpha, and 5 x 10-8 microcurie per milliliter or better for Sr-89 anci Sr-90, which is in accordance with with the guidance of NUREG-0472.

NUREG-0472 LLD's, however, are based on typical' plant designs and site -

characteristics. By definition in the Rancho Seco ODCM, the LLD is the smallest i

concentration of radioactivity in a sample which will be detected and reported as a positive value approximately 95 percent nf the time. Conversely, a sample with no real net activity above background will be reported as a positive value about 5 percent of the time. The LLD is a predictive estimate representing the capability of the measuring system, not an after-the-fact estimate for a particular sample.

As reported in the Rancho Seco, " Radiation Exposure, Environmental Protection, Effluent and Waste Disposal 1984 Annual Report," there were no liquid effluent releases for that year with detectable levels of Strontium-90, Cobalt-57, Zinc-65, Chromium-51, Iron-59, Molybdenum-99, Technetium-99m, Barium-Lanthanum-140, and Cerium-141. Regulatory Guide (RG) 1.21, " Measuring, Evaluating, and Reporting Radioactivity in Solid Wastes and Releases of Radio-ative Materials in Liquid and Gaseous Effluents from Light-Water-Cooled Nuclear l

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_4 Power Plants," provides that, if radioactivity in the sample is less than the detection capability of the instrument, then the value should be reported as less than the sensitivity of measurement (the numerical value is to be indicated). It is not clear from the Rancho Seco documentation reviewed whether the licensee used, for the purpose of calculating the reported offsite doses, the actual LLD values, or lesser values for radionuclides in effluent measurements where concentrations in excess of the LLD values were not detected.

The staff has calculated, based on the Rancho Seco 0DCM,* the annual offsite I

doses which would be attributable to each radionuclide if released at Rancho -

Seco in waste water at the LLD activity concentration specified in the Rancho Seco RETS. Based on the information provided in the Rancho Seco, " Radiation Exposure, Environmental Protection, Effluent and Waste Disposal 1984 Annual Report," it was assumed that the waste water is diluted 100-fold prior to discharge offsite. The calculated annual adult total body dose is about 79 millirems, with Cesium-134, Cesium-137 and Strontium-90 contributing about 40, 25 and 7 millirems, respectively. The calculated annual adult tane dose is about 82 millirems, with Strontium-90, Cesium-137 and Cesium-134 contributing about 26, 28 and 21 millirems, respectively. The calculated annual adult liver dose is about 101 millirems, with Cesium-134 and Cesium-137 contributing about 49 and 37 millirems, respectively. The calculated annual adult thyroid dose is about 41 millirems, with Iodine-131 contributing about 37 millirems.

In contrast, Rancho Seco Technical Specification 3.17.2. which is provided to implement the requirements of 10 CFR Part 50, Appendia I, requires that the annual dose to a raember of the public from radicac 4 in .erials in liquid i

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• Revision 3, dated 09-23-85, provided as Attachment 8 to Rancho Seco, " Effluent and Waste Disposal Semiannual Environmental Report, January to June 1985."

. effluents be limited to 3 millirems to the total body and to 10 millirems to any organ. Rancho Seco Technical Specification 3.25, which is provided to meet the dose limitations of 40 CFR 190, requires that the annual dose to a member of the public due to releases of radioactivity and radiation from fuel cycle sources be limited to 25 millirems to the total body or any organ (except the thyroid, which is limited to 75 millirems).

Clearly, the incorporation of the model RETS LLD values in the Rancho Seco RETS is an error since use of these values can result in releases of radioactive materials.to which offsite doses may be attributed (through the use of the methodology of the ODCM) that are in excess of the limits provided by the RETS .

to implement the regulations, 10 CFR Part 50, Appendix I, and 40 CFR Part 190.

To the extent that a significant dose contribution may be present at Rancho Seco due to the release of radioactive materials in concentrations below the

. LLD values, and dose calculations based on these releases do not adequately account for possible radioactivity in these releases, the potential may exist for concentrations of radioactive materials and levels of radiation in the environment that are higher than expected on the basis of the effluent measurements, and possibly exceeding regulatory limits.

The Rancho Seco RETS, utilizing the guidance of NUREG-0472, provide for an annual land use census to ensure that changes in the use of areas at and beyond the site boundary are identified and that modifications to the monitor-ing program are made if required by the results of the census. To the extent that significant changes in the use of nearby areas may occur and remain for significant periods of time until identified'in the annual land use census, a potential may exist for concentrations of radioactive materials and levels of radiation in the environment to be higher than expected on the basis of the previous land use census, and to possibly exceed regulatory levels. Such l changes may have a greater impact for Rancho Seco when compared to the more l

typical model plants because of the differences in site characteristics.

Thus, a more frequent land use census may be necessary.

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The Rancho Seco 0DCM is based on and closely follows the guidance provided in RG 1.109, " Calculation of Annual Doses to Man from Routine Releases of Reactor Effluents for the Purpose of Evaluating Compliance with 10 CFR Part 50, Appendix 1." RG 1.109 is also based on typical reactor plant designs and site characteristics. The basic features of the calculational models described in RG 1.109 are general approaches that the NRC staff has developed for appli-cation in lieu of specific parameters for specific sites. RG 1.109 encourages the use of site-specific values, assumptions and methods.

Calculational methods for doses due to liquid effluents are provided in RG

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1.109 for the pathways of potable water, aquatic foods, direct radiation from .

shoreline deposits, and foods grown on land irrigated with contaminated water.

The calculational model provided in RG 1.109 for the aquatic foods pathway assumes that the concentrations of radionuclides in aquatic foods are directly

. related to the concentrations of the radionuclides in .the- water. The model, therefore, does not take into account the effects of the long-term buildup of concentrations of the radionuclides in bottom sediments on the doses due to ingesting aquatic foods (bottom-feeding fish). However, for purposes of cal-culating annual direct doses from shoreline deposits, the models of RG 1.109, do take into account the long-term buildup of radionuclides in sediment due to the transfer of the radionuclides from the water to the sediment over the facility operating life. Further, for the purpose of calculating annual doses from consumption of foods grown on irrigated land, the long-term buildup of radionuclides in soil is also accounted for. Calculational models are not provided for doses from liquid effluent releases due to swimming and due to direct radiation from the long-term buildup of radionuclides on land irrigated j with contaminated water.

The Rancho Seco 0DCM, Revision 3, states that the models account for all potential land, water usage, and food radiological exposure pathways that could actually exist downstream from Rancho Seco. However, the models do not take into account the effects of the long-term buildup of conc:ntrations of radionuclides in

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l 7 1 bottom sediment on doses due to ingesting aquatic foods, or direct radiation from the long-term buildup of radionuclides on land irrigated with contaminated water. Therefore, to the extent that a significant dose contribution may be present at Rancho Seco through the omitted pathways, a potential may exist for concentrations of radioactive materials and levels of radiation in the environment that are higher than expected on the basis of the existing modeling  !

of the environmental exposure pathways, and for these levels to possibly exceed regulatory limits.

The Rancho Seco RETS Environmental Radiological Monitoring Program provides for the collection and analysis of specifed numbers of samples of surface water, runoff water, shoreline mud and silt, milk, fish, and several classes of harvested food at specified frequencies. This program is based on the guidance of the model program in NUREG-0472. The sampling locations are described in the

. ODCM. The RETS provide reporting levels for radionuclide concentrations in the environmental samples in order to appropriately identify when concentrations of radioactive materials and levels of radiation may be higher than expected on the basis of'the effluent measurements and the modeling of the environmental exposure pathways.

Based on the above information, we conclude that the situation at Rancho Seco involving the availability of only minimum quantities of cooling and receiving water for dilution of liquid effluents is highly atypical. Therefore there is a greater likelihood that offsite doses will approach the dose limits when compared to the more typical plants envisaged by the regulatory standards with similar waste characteristics and waste treatment to that at Rancho Seco. The Rancho Seco RETS provide requirements for effluent monitoring, nearby land use identification, offsite dose calculations, environmental monitoring, and limitations on offsite doses. The RETS and the ODCM are patterned after model requirements which are based on more typical plant designs and site characteristics. Therefore, to provide assurance that plant operation maintains releases below the dose limits, atypically greater levels of accuracy or conservatism may be needed in quantifying liquid releases, identifying nearby

~.. o land uses, and calculating offsite doses at Rancho Seco. Further, an error exists in the Rancho Seco RETS LLD values which can result in doses attribut-able to liquid effluent releases that are in excess of the RETS limits for maintaining compliance with the requirements of 10 CFR Part 50, Appendix I and 40 CFR Part 190.

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