Friends due to shifting of my flat I was unable to post  on this topic. Now it will be in continuation. Sorry for this huge gap. So this continuation starts now.....................

Q46. Why plutonium pumps have been put in glove boxes whereas some pumps are in thick shielding?

A.     Plutonium pumps are kept in glove boxes to avoid spreading of air activity and they are shielded to

         avoid the radioactivity release.

Q47. What are various radiation zones in plant?

A.      WHITE    - Low Block,                                 GREEN – Change room and Corridor,

          AMBER  - Lab, A/G, FHA, S/G,                  RED       -  Hot cell, Enclosure, Glove box.

Q48. What care is taken in different zones?

A.    For White & Green zones – no special care is necessary, for but spreading of contamination from  Amber area to this area should be avoided for Green zone, for Amber zone, TLD badges and plant clothing and shoes are essential, also while entering this area, HP instructions are to be followed by raising SWP. For Red zone, special instructions by HP should be followed as per their survey, double boiler suit or PVC suit etc are necessary.

Q49.What are the units of radiations, old and new?

A.    Old unit of radiation is RONTENGEN  (R) and new unit is SIEVERT (SV) or MSI. Conversion

        100 rem  = 1 SV.

Q50. What are limits for life time radiation exposure for different type of radiations?

A.      Limit for life time radiation exposure for different types of radiation is 100R.

Q51. How exposure is controlled? What is SWP?  How & why various clearances are taken?

A.    Exposure is controlled by time, distance & shielding methods and wearing gas masks. SWP is special work permit raised for a job.  SWP is used for having coordination between initiating officer, work carrying agency, area in-charge HP and control room.

Q52. What are various limits and tolerance for air activity?

A.      Various limits and tolerance for air activity:

       

Pu 239 W class	DAC	0.08 BQ/m3
Pu 239 Y class	DAC	0.2 BQ/m3
Pu CS 137	DAC	2000.0 BQ/m3
SR 90	DAC	300.0 BQ/m3
Natural U.(Nitrate)	DAC	20.0 BQ/m3
Natural U.(Oxides)	DAC	0.6 BQ/m3

Q53. What chemicals are used in washing contamination?

A.     Various chemicals are used for decontamination: Water, Soap, EDTA, Citric acid, KmNO₄, dilute

         H₂SO_4.

Q54. A contamination of 100 cps is considered high, medium or low?

A.    100 cps contamination will be considered as per zones.

RED zone	LOW
AMBER zone	MEDIUM
GREEN zone	HIGH
WHITE zone	VERY HIGH

Q55. What care is to be taken to avoid say hair getting contaminated?

A.    Hair contamination can be avoided by using caps.

Q56. What will you do if hair get contaminated?

A.      If hair get contaminated, they should be washed thoroughly with soap and then hair should be checked

         by HP and his instructions are to be followed.

Q57. What is the difference in dosimeter and TLD?

A.      TLD is measuring monthly exposure (cumulative). Dosimeter is used for spot exposure assessment.

          TLD has very big range of measuring dose, and TLD has thermal luminescent power

          Dosimeter range                        -           0 to 5 R

          TLD range                                 -           up to 1000 R.

Q58. What are various radiation dose standards for radiation worker and population? What standards are

         followed in India?

A.     Radiation for worker – 3.5 R per annum, for Population – 200 mr per annum. Standard followed in India are ICRB, AERB, SRC and Radiation Protection Manual.

Q59. What are limits for Beta exposure and why? How they are measured and controlled?

A.    Limit for Beta exposure is 50 R being a less penetrative compared to Gamma and can be easily shielded. They are measured by Beta rad meter (GM tube). They can be shielded by PVC suit or aluminium sheet.

Q60. What are the harmful effects caused by radiation?

A.     Harmful effects caused by radiation are: Stochastic effect – Cancer of various types, i.e. blood cancer, lung cancer. Non-Stochastic effect – Cataract, skin lumps, skin erythems, sterility, radiation sickness death.

Q61. What is meant by ID, MPC, MPBB, DAC?

A.      ID         – Internal dosimetry conducted for checking radioactive material inside human body.

          MPC    – Maximum Permissible Concentration in air.

          MPBB – Maximum Permissible body bums.

          DAC    - Derived Air Concentration.

Q62. What are these values for different radio isotopes/fission products?

A.    Three radio isotopes of major concerned in PREFRE plant are:-

        Pu 239 is having W & Y classes & SR 90

DAC for Pu 239	0.08 BQ/m3
DAC for Pu 239	0.2 BQ/m3
DAC for SR 90	300.0 BQ/m3

Q63.   How man-rem budgeting is done?

A.     Individual exposure is controlled by time, distance & shielding. Update data of individual is kept recorded and man will be replaced if one is fully exposed in a month.

Q64.   How do you say that a particular radiation job has been carried out with adequate or minimum

           exposure?

A.      If dose received by personnel who handles radiation job was minimum and if they have not spread contamination to other area. Then we may say that job is carried out with minimum exposure.

Q65.   What are the relative merits of various shielding materials used in reprocessing plants?

A.     Various shielding materials used in plant are: Water, lead sheets/blocks/bricks, and concrete. For Alpha & Beta : Perspex sheets, thin aluminium foil, PVC sheet, mild steel (sampling blister, pump remote head cubicles), lead (fuel charging and transport flasks, lab hot cells) Perspex and water ( fuel handling pond), earth shielding for WTA & High active transfer lines, Concrete is used for radiation coming from cells.

Q66. What are the process chemicals which effects concrete, epoxy paint and floor tiles (PVC & marble)

          thereby giving fixed contamination?

A.     ALARA means as low as reasonably achievable. It is associated with optionisation we should justify    the action taken, optimize the resources and comp lane with safety rules.

Q67.  What are dosimeter and TLD & why both are used by worker?

A.    Dosimeter gives the spot assessment of the radioactive dose exposed to worker and TLD gives the accumulated dose. Worker in a month, dosimeter should be used by a worker while working where a dose is more so that he cannot be over exposed as dosimeter gives the dose immediately.

Q68. When a dosimeter is tied on hand and why?

A.    Dosimeter is tied on hand to know the dose for which hand is exposed when hands are exposed to high radiation dose.

Q69. Describe the use of GM counter, contamination monitor, portable monitor and hand monitor?

A.     

GM Monitor	Used for Air sampling counts, contamination on floor & equipment (Beta and Gamma)
Contamination Monitor	Used for checking Beta and Gamma contamination which may be fixed or loose
Portable Monitor	Used for showing fixed and loose contamination
Hand Monitor	Used to check hand contamination

Q70. What care should be taken while using these instruments?

A.    The window of these instruments is of very thin glass which is very delicate so it is covered with metallic gauge. The instrument itself should not get contaminated so polythene sheet is muffled over it.

Q71. Hand counter in hand monitor shows 93 and clear light, what does it mean?

A.     If clear light is there, it shows that contamination is permissible or background contamination is there.

Q72. If contamination monitors give continuous buzzer at very high frequency, how will you measure your

         contamination level?

A.    Contamination monitor giving alarm means you are badly contaminated and if it has ranges, go to the higher ranges where the meter shows the reading. During alarm condition, meter may go off scale so you are not able to measure contamination so keep the instrument at higher range.

Q73. While working in sampling gallery if continuous air monitor gives alarm, what will you do?

A.    While working in sampling gallery if continuous air monitor gives alarm then one should come out of sampling gallery and report to HP & Control room.