Nuclear reactors endangered with damage to concrete

Part II: Nuclear Power Stations Need Testing for Concrete Damage – Comment Deadline Monday, March 30th,  2015   by  Deadline is on Monday, March 30th, 11.59 Eastern Time (DC) – one minute to midnight- for whether the US NRC should use proper methods to detect concrete degradation at Nuclear Power Stations: “The petitioner requests that the NRC amend its regulations to improve identification techniques against ASR concrete degradation at U.S. nuclear power plants. The petitioner suggests that the reliance on a visual inspection does not ‘adequately identify Alkali-Silica Reaction (ASR), does not confirm ASR, or provide the current state of ASR damage (if present) without petrographic analysis under current existing code.http://www.regulations.gov/#!docketDetail;D=NRC-2014-0257 (Comment at link; can be anonymous.) It is critically important to also ask for ultrasonic testing for damage to the nuclear reactor pressure vessel, even though it is not on the docket. See:https://miningawareness.wordpress.com/2015/03/03/nuclear-reactor-cracks-widespread-disease-scourge-warns-nobel-in-chemistry-nominee/

The average age of US commercial nuclear reactors is 34 years with the oldest being over 45 years old (EIA, 2015). Even in the best of circumstances, concrete suffers age related damage. But, nuclear power stations suffer from extreme conditions. According to William et. al., for the NRC (2013):
All commercial NPPs in the United States contain concrete structures whose performance and function are necessary for protection of the safety of plant operating personnel and the general public as well as the environment. A myriad of concrete-based structures are contained as a part of a light-water reactor (LWR) plant to provide foundation, support, shielding, and containment functions. Typical safety-related concrete structures contained in LWR plants may be grouped into four general categories: primary containments, containment internal structures, secondary containments/reactor buildings, and other structures… there may be a coupling effect between radiation and ASR that can potentially accelerate ASR activity or cause ASR to occur with aggregates that are not normally reactive. As plants age, the potential of ASR to occur in structures forming the biological shield or support for the reactor pressure vessel may increase as these structures are located in areas in which they are subjected to moderate elevated temperature in combination with radiation… ASR capable of being detected visually, however, is probably in a fairly advanced stage of development“. (William et. al. NRC, 2013, p. 83, pp. 88-89)

Unfortunately, the problem of concrete and radiation isn’t going away on 11.59 pm Monday. Not only is concrete used in nuclear power stations, but it is also an issue for spent fuel pools, dry cask storage, burial of nuclear waste – whether a “facility” like WIPP, or burying it in concrete lined trenches or burying concrete casks in unlined trenches. Also it may be used for above ground temporary storage of nuclear waste. For these other problems one must also take into consideration high LET alpha radiation-bombardment, along with low LET gamma radiation and high LET neutron bombardment. Worse, someone had the stupid idea of putting concrete in some nuclear waste storage drums with the waste……..

8.2 SPECIFIC CONDITIONS RELATED TO THE EFFECT OF RADIATION ON CONCRETE

NPP concrete structures, particularly those related to the biological shield or support for the reactor pressure vessel, can be subjected to neutron and gamma radiation during their service lives. As the service lifetimes of these plants are being extended, the impact of radiation on the concrete structures may have increased significance that can affect their functional and performance requirements. Irradiation of concrete has the potential to impact the concrete’s microstructure as well as its mechanical and physical properties. An assessment of the impact of radiation on the concrete microstructure and properties would require removal of concrete samples from the areas of interest and application of techniques such as identified in Tables 8.1 and 8.2.

In addition to the impacts of radiation on the microstructure and properties of concrete, radiation can contribute to elevated temperatures in the concrete as well as increased potential for ASR and concrete carbonation to occur. Techniques associated with identification of concrete that has experienced or is experiencing elevated temperatures, ASR, or carbonation may also provide indications that the concrete has been affected by radiation.” (William et. al. NRC p. 87)……..

10. SUMMARY AND CONCLUSION

Gamma rays … can result in the destruction of anisotropic chemical bonds such as covalent bonds. Water in the concrete can be decomposed by gamma rays by a process called radiolysis and can be converted to hydrogen, oxygen, and hydrogen peroxide. Water can also be removed from the concrete by evaporation due to heat generated by gamma radiation. Because most of the water in concrete is contained in the cement paste, gamma radiation has a greater effect on the cement paste than it has on the aggregate materials………

A Review of the Effects of Radiation on Microstructure and Properties of Concretes Used in Nuclear Power Plants” Manuscript Completed: August 2013 Date Published: November 2013  IF YOU READ THE ORIGINAL YOU MAY NOTE THAT THERE APPEARS TO BE A PRO-NUCLEAR AUTHOR OPPOSED TO NUCLEAR SAFETY WHO GOES THROUGH HERE AND THERE AND MAKES STATEMENTS WHICH CONTRADICT THE INFORMATION AND NUMBERS GIVEN IN THE STUDY. BE ALERT!http://permanent.access.gpo.gov/gpo42084/ML13325B077.pdf
ANOTHER STRANGE THING IS THAT THEY SAID THAT FREEZING WOULDN’T IMPACT CONTAINMENT AND YET THERE WERE REPORTS OF A LOT OF SNOW BUILD-UP ON TOP OF DAVIS BESSE NUCLEAR POWER STATION. WASN’T THE OWNER BLAMING THE SNOW FOR CRACKS IN DAVIS BESSEE CONTAINMENT? IF SNOW BUILDS UP THEN THERE MUST BE SOME CHANCE OF FREEZE THAW EFFECT, ESPECIALLY WITH GREAT LAKES SNOWS. https://miningawareness.wordpress.com/2015/03/29/part-ii-nuclear-power-stations-need-testing-for-concrete-damage-comment-deadline-monday-march-30th-11-59-et/

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