From Agency France Press (AFP) via France 24, June 13, 2020
https://www.france24.com/en/20200613-france-says-no-nuclear-accident-during-submarine-fire comes:
https://www.france24.com/en/20200613-france-says-no-nuclear-accident-during-submarine-fire comes:
"France says 'no nuclear
accident' during submarine fire
[Toulon Naval Base,
France] A fire that raged for 14 hours on [the Perle (S606)(English “Pearl”) one of France's
[Rubis-class SSNs] did not lead to an
atomic accident as steps were taken to protect its reactor, the defence
minister said [on June 13, 2020].
The submarine was
under renovation in the southern base of Toulon when the blaze broke out at
about 10:30 am (0830 GMT) on [on June 12, 2020] in a hard-to-access part of the
lower bow section, the [French] navy said.
It then took around
100 firefighters and 150 support crew to put out the blaze by around midnight
(2200 GMT [June 12, 2020]), the navy said in a statement.
"There was a
fire, but no, there was not a nuclear accident," Defence Minister FlorenceParly said.
Parly added that
during the fire "measures were taken in the rear area to protect the
nuclear reactor compartment".
The navy said earlier
there were no casualties and no risk of radiation because the nuclear fuel had
been removed during the renovation of La Perle (The Pearl), one of France's six
nuclear attack submarines.
The extent of the
damage -- and what started the fire -- were not immediately clear but an
official with the Naval Group repair centre called the incident
"serious."
The regional
authorities said that pollution and radioactivity tests carried out by
independent experts had not found anything out of the ordinary.
But French nuclear
watchdog association CRIIRAD said that a nearby measurement found that
radioactivity levels had oscillated at low levels for a few hours in the days
leading up to the fire.
The NGO said the
"troubling" phenomenon "could have several explanations,"
but that it did "raise questions".
Parly responded by
saying that "a natural radioactive element was emitted in infinitesimal
quantities before the fire," adding that it showed that "we have an
extremely sensitive and effective detection system".
Parly said a damage analysis would determine whether the vessel can be repaired, adding that it was lucky that almost all of the sub's equipment was not on board.
Parly said a damage analysis would determine whether the vessel can be repaired, adding that it was lucky that almost all of the sub's equipment was not on board.
A judicial
investigation and technical probe have been launched.
The submarine, which
entered service in 1993, docked at Toulon in January for 18 months of
renovation work that was to keep it operational until the end of the decade...”
1 comment:
Heating of steel by fire and its cooling by water may resulting of significant damage of steel [1, 2]. According to submarine design experts, even tiny damage of steel by heating and/or cooling will provide serious results [3,4]. Degree of fire damage including wiring system should be precisely measured and assessed. Perle will be scrapped at the worst case like the case of USS Miami [5]
[1]https://www.steelconstruction.info/Fire_damage_assessment_of_hot_rolled_structural_steelwork
“The assessment of fire damaged hot rolled structural steel is an area in which many engineers and architects have little practical experience. On many occasions fire affected steelwork shows little or no distortion resulting in considerable uncertainty regarding its re-usability. This is particularly true in situations where fire has resulted in some parts of the structure exhibiting little or no damage alongside areas where considerable damage and distortion are clearly visible.”
[2] https://www.jstage.jst.go.jp/article/jssc/21/84/21_84_67/_pdf “Effect of heating and cooling process assuming fire of steel bridged on characteristics of welded joints of structural steel”, Steel Construction Engineering, vol.21, No84, ”Dec/2014, page 67, M. Hirohata, et. al.
“For investigating the effect of heating and cooling process assuming fire of steel bridges on characteristics of welded joints of structural steel members, a series of experiments were carried out. The heating under transformation point did not affect the joint performance regardless of cooling process. The heating over transformation point caused the softening or the hardening according to cooling rate. The degree of them was larger in the base metal rather than in the weld metal because the amount of carbon in the base metal was more than that in the weld metal. Furthermore, the change of microstructure of base metal made by TMC process was more sensitive compared with that of weld metal.”
[3] https://www.jstage.jst.go.jp/article/kyokaisi/460/0/460_KJ00002224747/_pdf “Issues on structural material and construction of submarine”, The Society of Naval Architects of Japan, No 460, Oct/1955, page 429, T. Sugimura et.al. (Technical Research and Development Institute, the Japan Defense Agency).
“USS Thresher sank in 1963 was caused by fracture of welded parts of pipe with 10cm diameter. Risk of facture must be understood.”
[4] ibid, page 429
“There are two requirements in steel materials for submarine including welded parts: Standard Charpy strength at -70C and -2.2 C shall be more than 2.2kgm and 7kgm, respectively.”
[5]https://en.wikipedia.org/wiki/USS_Miami_(SSN-755)
Regards
S
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