ML18348A692

Response to Request for Additional Information Proposed Emergency Dose Assessment System

ML18348A692
Person / Time
Site:	Palisades
Issue date:	05/12/1977
From:	Hoffman D Consumers Power Co
To:	Schwencer A Office of Nuclear Reactor Regulation
References
Download: ML18348A692 (8)

Text

consumers

• Power company General Offices: 212 West Michigan Avenue, Jackson, Michigan 49201

• Area Code 517 788-0550 May 12, 1977 Director of Nuclear Reactor Regulation Att: Mr Albert Schwencer, Chief Operating Reactor Branph No 1 US Nuclear Regulatory Commission Washington, DC *20555 DOCKEI' 50-255 - LICENSE DPR PALISADES PLANT - PROPOSED EMERGENCY DOSE ASSESSMENT SYSTEM:

In accordance with discussions with members of the Nuclear Regulatory Commission staff on March 16, 1977, Consumers Power Company agreed to submit for the staff's formal review a description of a proposed emergency radiation dose assessment system at the Palisades Nuclear Plant. This emergency dose assessment system is in response to recoinmendations provided in NUREG-0125, Draft Addendum to the Final Environmental Statement. The components of this emergency system include a new meteorological tower, an upgraded stack monitoring system, and an elec-tronic processing unit to provide off~site dose calculations as a function of meteorological conditions and effluent release rates. Although the system will be designed specifically for response.to high release rate emergency events, low level measurement capabilities will be provided within the limits of prac-ticability .

Descriptions of the meteorological, stack monitor and data processing components of the emergency radiation dose assessment systems are outlined below.

I. Meteorological System In response to the staff's recommendations in Section 6.4 of NUREG-0125, the following responses outlined Consumers Power Company's overall position. The criteria are explained in more detail in Section II Meteorology.

Staff Recommendation 1: "The applicant submit for our approval proposed modifications to the present on-site meteorological measurement program that will provide meteorological dat*a representative of conditions at both the point of release and at the inland site boundaries."

• Response: We have determined that a single meteorological tower situated at the edge of our site and in the ENE sector would be the best alternative to our present system.

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• Staff Recommendation 2: "Instrumentatio~ on all meteorological tower(s)

'should meet the recommendations of Regulatory Guide 1.23 unless the ap-plicant can demonstrate that deviations from these recommendations are warranted."

Response: We agree to use instrumentation on the meteorological tower that meets the recommendation of RegUlatory Guide 1.23 if sensor technology permits.

Staff Recommendation 3: "The applicant submit one year of additional meteorological data, with greater than 90% data recovery from the modi-fied measurement program, as soon as these data are available."

Response: The system is designed to achieve the 90% data recovery goal.

One year of new data will have to await the installation of the proposed new to~er. We request expeditious review of our proposed system so that we may initiate construction according to the attached schedule.

II. Meteorology A. 'Tower Location The location of a meteorological tower will be on a hilltop, off the Blue Star Highway, north of the main entrance to the plant. (See attache4 aerial photo, Figure 1.) 'This site was considered because:

1. It .has the same exposure as the plant stack and is at about the same.height. The stack top is 780 feet above mean sea level (MSL) while the base of the tower will be about 720 feet above MSL.

2. It is at the edge of the plant boundary and is, therefore, most representative of meteorological conditions used for dose calcula-tions to population centers within a 50-mile radius of the,plant.

3. It is in a region of more stable soil conditions and a minimal amount of trees will be lost due to site preparation.

4. It has a good security potential because it is clearly visible from the main roads.

5. It is in an area not disturbed by building wake effects, plant construction activities, cooling tower influences and drainage winds from the surrounding dunes.

6. Our site investigation showed that this tower location is the best location possibl*e and has minimal adverse conditions as described above .

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• B. Tower Height The proposed tower will be l95 feet in height. This tower height will allow the direct measurement of the stability of the air layer (delta T) in which the released radioactive material is *traveling.

C. Sensors and Application of Regulatory Guide l.23 The tower will be instrumented at the lO- and 60-meter levels. At the lO-meter level, wind speed, wind direction, air temperature and dew point temperature will be measured. At the 60-meter level, wind speed and wind direction will be measured. The temperature difference (delta T) will be measured between the lO- and 60-meter levels.

Instrumentation accuracy will conform to Regulatory Guide l.23 require-ments except for very low wind speeds and the dew point temperature.

Reliable instrument manufacturers can guarantee a starting threshold of less than l mph. However, they advise that wind speed accuracy of

+/- 0.5 mph can only be achieved at wind speeds above approixmately 3 mph.

For the dew point temperature sensors, our experience indicates that lithium chloride dew cells are the most reliable recording field instru-mentation available, but they have a typical accuracy of+/- l°C .

• Meteorological recorders and spare parts will be housed in an environ-mentally controlled shelter near the tower. Digital signals will be cabled to the minicomputer in the power plant where the data will be polled at least every 60 seconds, averaged over a l5-minute period and printed on a computer tape and teletype paper.

D. System Protection The wind instrumentation will be internally heated, the tower instru-mentation and recorders will be grounded and surge protection devices will be installed to reduce the potential data loss due to icing and lightning surges. Security fences will be erected to prevent equipment vandalism.

III. Stack Monitor The proposed stack monitor portion of the dose assessment system will be similar to the Eberline Instrument Corporation's PING-2 system for measure-

• ment of particulate beta, iodine-l3l and noble gas. A block diagram for a customized PING-2_system is shown in Figure l. The only differences anticipated from the standard PING-2 (should the Eberline system be chosen based upon bid competition) would be possible use of a gamma scintillator

• for xenon-133 rather than beta scintillation for total noble gas, and addition of sample flow rate data input to the processor. Stack flow also would be used as input to allow real time effluent release calculation over

• the full range of sample and stack flow rates .

• Particulate and iodine-131 measurements would utilize fixed filters to be replaced at intervals of typically one-week duration. Upon filter replace-ment, the used filters would be analyzed for specific radionuclides in addition to iodine-131. The monitor would measure xenon-133 by gamma scintillation or noble gas beta via beta scintillation. In either the beta or gamma case, measurement would be made of the noble gas component within a fixed geometry chamber through which the effluent is pumped.

Thus, the noble gas measurement directly indicates release rate as a function of time, whereas the particulate and iodine measurements indi-cate the integral release and will utilize differential processing for release rate determination.

The detector location will be moved to a lower background radiation area (turbine building) than found at the present monitor lo"cation (auxiliary building above component coolant room). This relocation will allow in-creased accessibility for calibration and maintenance, and will provide for increased detector sensitivity due to lowered background in both the normal and accident environments.

IV. Data Processor The data processor will receive inputs from the meteorology instruments, stack monitor sensors, and stack flow rate sensor. Standard data collection intervals are proposed to be as indicated in Table I. Within the specified intervals, sampling rates would be approximately once per 60 seconds for meteorological data, once per 30 seconds for flow rates, and continuous integration for radiation counts. Whenever stack monitor detectors indi-cate a significant count above the previous significant count, the release quantity, meteorological joint frequency, and off-site receptor doses would be computed. These intervals would not necessarily represent spe-cific controlled release intervals such as waste gas decay tank releases.

This is because these releases might result in less than a significant count or, on the other hand, could result in several significant counts over the release interval. In order to relate meteorology to actual release intervals or other periods of interest, an attempt will be made to program the processor with capability for data summaries and dose calculations for specified (input) intervals. It is unknown at this time whether the on-line processor will be capable of this function, or whether stored data will require off-line processing via a larger computer.

v. Project Schedule Figure 3 provides a preliminary estimate of the project schedule. Due to the winter conditions at the Palisades Plant site, it is unlikely that the installation can be completed prior to the summer of 1978 .

• David P Hoffman Assistant Nuclear Licensing Administrator CC: JGKeppler, USNRC

5 TABLE I

• PROFOSED EMERGEijCY DOSE.ASSESSMENT SYSTEM DATA OUTPUT INTERVALS AND DESCRIPTION Interval Determination A. Each 15 minutes 1) Sample Activity

2) Atmospheric Diffusion Parameters B. Significant (2d)* 1) Release over Interval Count Difference* 2) Joint Frequency over Interval

3) Receptor D:>ses over Interval

c. Weekly 1) Release During Week

2) Off-line Parti.culate Gamma

3) Off-line Unidentified Beta Quarterly (or other

. D . **specified 1) Release During Period

.interval) 2) Receptor D:>ses

3) Population D:>se

4) Joint Frequency Distribution

5) Composite Off~Line Sr-90 E. Annually 1) As in D, above

'i

• .Interval required for 2 o' significance of count. Example - 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> of I-131 buildup on filter would be expected to provide a significant count increase if release were at a rate which would give Appendix I dose in one year

• Figure l - Proposed Meteorological Tower Location

• PALISADES PLANT 1000 0 1000

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• 1 I

• FIGURE 2 Typical Stack Monitor System

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8 FIGURE 3

• Palisades Meteorological Tower Task/Schedule/Plan Months After NRC ApprovaJ.

1 2 3 4 5 6 7 8 Activity

1. Permits (FAA, Local, etc)

2. Consultant Selection llllllll!llll/IA

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4. Site Preparation (Access Road, Clearing) v71111111111111n

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6. M:!teorologicaJ. Equip-

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ment Assembly & Test

7. Data Telemetry to Plant Stack Monitor

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9. System Operation

• NOTE: If either one of these tasks could not have a scheduled completion data of November 1, 1977, then project could be delayed to March 1, 1978. This delay is due to adverse weather conditions limiting outdoor con-struction during the winter months in this region *