ML19329C622
| ML19329C622 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 05/29/1975 |
| From: | Block S Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML19329C620 | List: |
| References | |
| NUDOCS 8002180136 | |
| Download: ML19329C622 (11) | |
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O Davis-Besse 1 Safety Evaluation Report Gene ral_
12.0 The Radiation Protection Program of the Davis 3 esse "uclear Pever Station is discussed in Chapter 12 of their FSAR.
In that Chapter the applicant has described the methods by which he controls radiation exposures within the limits of 10 CFR 20 and his plans to maintain exposures as low as practicable ( ALAP).
Accordingly, he discusses his design features including shielding and layout of facilities, his area monitoring prograc which details his radiolcgical and airborne radioactivity monitoring systes, his ventilation system for providing a suitable radiological environment and his health physics program to assure that exposures will be ALAP. This sectica of the Safety Evaluation Report presents our evaluation of the adequacy of this program in terms of the radiatica protection design and equipment features and the health physics program at Drvis Besse.
The review emphasis is on the applicants program for planning, designing and operating his facility to ecatrol and =aintain occupational radiation exposure to as lou as practicable.
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_ Shield wall thicknesses were determined using our accepted criteria for assumptions, mathematical models and codes.
Tha applicant has designated his areas in terms cf access during normal plant operation at power, hot standby, refueling, maintenance and component and systems testiag.
Consistent with the design, the applicant has pipes and valves carrying radioactive liquids (e.g.,
filters, demineraliaers, tanks, etc.) and sampling areas designed to be located in shielded compartments. Each equipment compar tment is individually shielded to reduce radiation levels inside adjacent ccapartments.
This isolation will allow maintenance, inspection, and some non-routine operations with no significant radiation interference from other co=partments.
In addition manually operated valves of contaminated equipment have reach rods which penetrate through shield walls or are located in accessible corridors.
Gages or other instruments can be inspected from cocridors or a central control board. No process piping is normally field run.
E:cisting process piping layouts and radiation zone diagrams will be used to guide proper installation of new piping whenever requirad.
In addition to the above, the following =easures are taken to reduce e
2::posuras; penetratiens throu;h shield walls are made at anglas to prevent streaming, and, if possible, piping makes a 90 bend after
, penetration and bulk shielding Lastalled behind it, also to preclude streaming; spent fuel pool penetrations are located so that their f ailure will not drata the pool to a point of insufficient water shielding. Portable shields will also be used whenever required to reduce exposures to ALAP.
Frem the plant as designed, the applicant's i
occupational radiation exposure to plant operating and maintenance crews from normal plant operatica, is predicted to be about 200
- man-res per year.
On the basis of the applicant's description of the design and the operating philosophy of the Davis Besse Nuclear Plant, we conclude that sufficient consideration has been given to the shielding and layou* of the f acility and cocponents to keep exposures to operating personnel within the applicable limits of 10 CFR Part 20 and to reduce unnecessary exposures during normal cperation of the facility to as low as practicable. 'Thile the applicant's estimate of occupational man-rem exposure is 200 man-res per year our studies show dhat the average dose to all onsite personnel at a typical large operating nuclear pcwer plant has been about 430 nan-rem per year.
This value may be higher in a given year depending upon unexpected maintenance, e
repair or inspection, or icwer during unusually trouble free years.
Our evaluation of ALAP however is based on stated design and operating
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principles and thus we find the Davis Besse =an-rem esti= ate to be ALAP and acceptable.
12.2 Area Monitoring The radiological monitoring systems are designed to continuously
=easure the radiation levels in areas coordinated with the station radiation access control requirements.
In general, area radiatica i
monitors are located where radiation levels could possibly increase due to postulated occurrences. Thus, operating personnel will have continuous knowledge of radiation zene compromise.
In addition, the monitors will provide some surveillance on radioactive materials that enter or exit the plant.
Each instrument of the system will have a sensor whose dose rate output is recorded in the centrol cabinet room and the main control room with multipoint recorders.
Both audible and visual alarms are available at the fixed location and centrol room.
Calibratien is performed semi-annually or on an as-required basis with a portable source calibrated against National Bureau of Standards sources.
The in-plant continuous airborne radioactivity monitoring system (CAM's) is designed to provide operating personnel with a continuous l
indicatien of airborne radioactivity in selected station areas. The system will detect and record airborne radioactivity concentrations i
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% so that appropriate action can be taken whenever alarm set-point levels are reached. These levels are set well below MPC relative to 10 CFR 20 Appendix B Table 1.
The system consists of ventilation monitors, upstream of EEPA filters,in the fuel handling area exhaust, radwaste area exhaust, penetration room exhaust, the control room ventilation system, as well as the containment vessel. Each monitoring system is equipped with capability to monitor particulates, iodines and noble gases.
Centrol, read out, recording and alars annunciation is installed in the centrol room.
This program will be combined with grab sampling and continuous air sampling monitoring techniques that will be employed during operations where significant airborne radioactivity could occur and CAMS are not available for use.
Based on the location of all radiological ?nd airborne radioactivity monitors, their sensitivity, range, recording and alarm annunciation features supplemented by an air sampling program, we conclude that the scope of the area monitoring program is satisfactory.
- 12. 3 Ventilation The Davis Besse ventilation system has been designed to provide a suitable radiological environment for personnel and equipment and to assure compliance with the limits of airborne radioactivity as set forth in 10 CFR 20 for restricted areas.
Throughout the station the
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path of the ventilation air will be from areas of low radioactivity 1
cowards areas of higher activity to prevent the spread of airborne T
radioactive materials and thereby ensure contamination control.,
Tne fuel handling and radwaste area exhaust systems are once-through i
systems and are provided with prefilter and HEPA filter banks.
a Non-radioactive areas are served by a separate ventilation system.
j The containment purge subsystem will provide a means of reducing 1
2 airborne contamination inside containment to allow personnel access.
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On-site inhalation exposures are intended to be kept as low as I
practicable during normal operations and maintenance by personnel training, airborne, radioactivity monitoring, contamination control j
and special work permits. Respiratory protective devices will be i
worn whenever airborne radioactivity levels warrant their use.
Since noble gas exposures are limited by whole body exposure criteria, 1
their dose will be controlled within the limits of personnel exposure in accordance to 10 Ca 20.10L Tritium exposures will be ccatrolled by supplied air = asks and special plasti: entes.
1 We conclude that the ventilation system is based on a design criteria I
that provides reasonable assurance that the system has the capability a
to maintain cencentrations cf airborna activity, in areas normally 1
occupied, in accordance with 10 Cn 20.
Also, radiation protection operating procedures should keep inhalation e: oosures to personnel as low as practicable.
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. G.M. and proportional counters for gross alpha, beta and gnmn coun ting as required for in-plant radiation protection. A TLD reader is also in the counting room to read-out TLD crystals for personnel dosimetry and radiation surveys.
Protective clothing and respiratory protection is available to all personnel. A respirator fitting program will be adopted and instructions will be given to all operations personnel on care and use of each type of respirator.
Continuous evaluation and review of the radiological status of the station will be carried out by health physics perscnnel, so that the levels of radiation will be known at all times in all areas where personnel will be working.
Control of radiation exposures will b:
caintained by use of such devices as roping, tagging, si gns, alarms,
and other access control measures to preclude unauthorized entry into high contamination areas.
Special work permits and procedures will be issued to allow uork in radiation control areas, and trained personael will be authorized to handle licensed radiation sources and by-product caterial.
Health physics instrc=ents for radiatica surveys censist of alpha, beta and gan=a survey =eters that include G.M. and croportional J
ccuntars and ionization faarbers. Neutren desa equivalen: will be ceasured using a spherical type re:-counter. All personnel will be l-
12.4 Health Physics This section of the Davis Besse SAR has been reviewed to determine that the health physics program will assure that occupational exposures will be ALAP.
The review covered the organizational structure, the health physics program, facilities, and conitoring equipmen t, and procedures related to contamination control and radiation exposures.
YLe health physics program and responsibilities are carried out by the Health Physics Section that reports directly to the Station Superintendent on matters concerning any phase of radiological protection.
The applicants stated policy for radiation protection is based on appropriate NRC regulations. Accordingly, health physics programs and radiation safety procedures will be adopted conforming to dhe principlas of keeping radiation exposures ALAP.
Consistent with these prograts and procedures, the health physics f
maintains the folicwing f acilities for conducting their routine operations; a counting room for counting smears and air samples, a calibration room for checking health nhysics instruments, i central access control point for changing clothes, nd a storage area for radiation protection equipment.
The counting room has radiation a
det2ctica systens to perform gamaa spectremetry by use of :iaI and GE(Li) detectors, a liquid scintillatica counter for tritium, and I
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. assigned a thermoluminescence dosi=eter (TLD) to be worn at all times.
Self-reading dosineters will be issued to those individuals whose work conditions make day to day indication of exposuras desirable and will se maintained by the health physics staff for recording daily exposures.
Dosineter records will furnish the exposure data necessary for ' etter adminiscraticn of centrol of radiation exposures. A a
bicassay progras consisting of whole body counting vill be conducted annually on individuals who have occasion to work in a radiation access control area where airborne radioactivity is likely to be present.
A program of this type is necessary to provide complete data on the effectiveness of the in-plant air monitoring pro 3 ram.
A urinalysis bicassay program for tritium will also be conducted on selected individuals who work in areas where there is a possibility for tritius inhalation based on tritius conitoring surveys.
We conclude that the applicants health physics progran and related procedures and equipment for in plant radiation safety is of sufficient scope to recude personnel exposures to levels that are as 1~v as practicable as required by 10 CFR Part 20 and is accaptable.
I 12.3 Radioactive :faterial Safety e
The applicant will implement a radioactive aaterial safety progr2 to assure the safe storage and handling of radioactive sourcas.
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All licensed source and by-product material, including neutron and ga ma sources, used for sample analysis and calibration will be stored in shielded containers in a locked s torage room.
The containers will be posted or locked in accordance with 10 CFR 20 re gulations.
When handling sources, remote handling devices and shields will 'ae used to keep personnel e: posures ALAP. Only personnel with special training shall handle licensed radioactive sources and by-product material. Unsealed sources will be handled La the fu=e hood of the hot laboratory designed to handle these type sources.
On the basis of the propcsed program for handling and storage of sealed and unsealed special radioactive materials, we conclude that the applicant will conduct a satisfactory r adioactive caterial safety program.
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