breached nuclear fuel, BWR, damaged nuclear fuel, dry cask storage, exceptions, exemptions, gross breach, grossly breached, Holtec, nuclear safety, nuclear waste, Spent Nuclear Fuel, US NRC
Less than 24 hours (11.59 pm Mon. March 9th Washington DC-EDT/ 4.59 am Tuesday UTC) to comment regarding storage of damaged nuclear fuel rods and other safety related exemptions to be given to Holtec. Remember to make the comment uniquely your own, because they don’t count repeats. https://www.federalregister.gov/articles/2015/02/05/2015-02310/list-of-approved-spent-fuel-storage-casks-holtec-international-hi-storm-100-cask-system-certificate
Something to think about as you read the proposed Holtec-NRC update to what counts as damaged fuel.
“Damaged Spent Nuclear Fuel at U.S. DOE Facilities, Experience and Lessons Learned, by INL (Brett Carlsen, et. al) , p. 2″ Metal oxides are but one serious problem. There are all sorts of unknowns regarding embrittlement by neutrons and hydrogen attack, too. Uranium, Plutonium, etc. in damaged-broken fuel rods corrode adding to the problems. Cesium is actually one of the most reactive metals.
How Breached is Breached? What is Grossly Breached? Are they checking? Holtec says that checking is too prohibitive in cost.
The applicant is Holtec. The Staff is NRC. NRC text in italics, our comment plain text in brackets:
“8.4 Update to Fuel Definitions/Classifications:
The applicant stated that adding the definition of undamaged fuel assemblies, grossly breached spent fuel rod, and repaired/reconstituted fuel assembly provides further clarity to the user and consistency with ISG-1, Revision 2 guidance on classifying fuel. In addition, the applicant contends these definitions will serve some BWR users who have older, low enriched, channeled BWR fuel with potential cladding defects that they wish to load without placement in a damaged fuel container.”
[Note that the concern is not public safety, but to serve those with Boiling Water Reactors (BWR) – about a third of US nuclear reactors – who have fuel with “potential cladding defects” for which they do not want to purchase a special container. What does Holtec mean by BWR “users”? Users of the Holtec system?]
“8.4.1 Undamaged Fuel Assembly
The applicant proposed adding the new definition “UNDAMAGED FUEL ASSEMBLY.” The applicant proposed that this is: a) a fuel assembly without known or suspected cladding defects greater than pinhole leaks or hairline cracks and which can be handled by normal means; or b) a BWR fuel assembly with an intact channel, a maximum planar average initial enrichment of 3.3 wt% U-235, without known or suspected GROSSLY BREACHED SPENT FUEL RODS, and which can be handled by normal means. An UNDAMAGED FUEL ASSEMBLY may be a REPAIRED/ RECONSTITUTED FUEL ASSEMBLY.”
[It is “undamaged” if there are not “known or suspected GROSSLY BREACHED SPENT FUEL RODS…” It can also have been “REPAIRED/RECONSTITUTED.”
NOTICE THAT HOLTEC SAYS KNOWN OR SUSPECTED AND YET THEY FIND THAT INSPECTIONS ARE TOO COSTLY. IT SOUNDS LIKE IF IT IS NOT “SUSPECTED” TO BE “GROSSLY BREACHED” IT IS THEN “UNDAMAGED”.]
“The applicant stated that “for channeled BWR fuel, inspections to classify the fuel cladding as undamaged in accordance with the currently approved definition may be prohibitive from a cost, ALARA, or safety perspective“.
[WHAT WILL BE MORE COSTLY AND DANGEROUS IS TRYING TO TRANSFER CORRODED, DAMAGED, BROKEN FUEL TO A NEW CASK IN THE FUTURE.]
“A particular subset of fuel, as described and analyzed in proposed FSAR Subsection 6.III.4.4, [low enriched, channeled BWR fuel] is shown to remain subcritical even if there was significant cladding damage and rearrangement of the fuel rods inside the channel. Therefore, if it can be determined that this fuel does not have gross cladding breaches, can be handled by normal means, and has enrichment less than or equal to 3.3 wt%, then it does not require a damaged fuel container nor is it limited to certain basket locations in the MPC-68M.” A specific example of this type of application is BWR fuel that has a condition of crud induced localized corrosion (CILC) which is copper induced. Potential corrosion-induced damage to the cladding, characterized by pitting, but not grossly breached spent fuel rods.
[3% is around the average enrichment for the average US light water nuclear reactor. Not grossly breached or not “known” or “suspected” to be? CRUD deposits hold heat. ]
“The staff’s evaluation in this area considered that, in BWRs, two types of crud deposits (plant corrosion products) can be found. The most frequently observed crud is low density, loosely adherent crud with good heat transfer capability. The other is a rarely observed tightly adherent crud of high density, through which lamination can lead to low heat transfer capability. Scale type crud contains high concentrations of copper, and heavy copper bearing crud was observed to be sandwiched between the zirconium metal and naturally occurring zirconium oxide at the cladding surface. This specific type of CILC has been discovered exclusively in BWR plants with copper containing condenser tubes.”
“Damage to spent fuel rods can be minor without causing gross cladding breaches or major that does cause gross cladding breaches. The applicant is only proposing to classify SNF rods that do not have gross breaches, along with the other specified conditions as undamaged.”
[No, it’s not what Holtec says. It says known or suspected, which appears a loophole. And what is a “gross breach”?]
“ISG-1, Rev. 2, provides guidance for classifying fuel as either undamaged or damaged. Undamaged fuel may contain some cladding defects if the fuel is safeguarded from high temperatures/oxidation, and does not contain gross cladding breaches. The HI-STORM 100 Cask System MPCs are backfilled with helium, shown to keep the peak cladding temperature of the fuel below the guidance limits in ISG-1 therefore fuel is protected during storage from temperatures that would lead to gross ruptures. As long as the fuel does not already contain a gross breach, ISG-1 concludes that there is no means to release fragments during storage. In addition, fuel that contains an assembly defect may be considered undamaged per ISG-1 if it can still meet fuel-specific and system related functions; therefore repaired and/or reconstituted assemblies, as proposed in the definition as part of this change, are considered undamaged.”
“Therefore, the staff finds that the applicants proposed definition of undamaged fuel complies with the specified conditions described above and meets the requirements of ISG-1 and is therefore acceptable.
8.4.2 Repaired/Reconstituted Fuel Assembly:
The applicant has proposed the following definition for “fuel assembly”: “Spent nuclear fuel assembly which contains dummy fuel rod(s) that displaces an amount of water greater than or equal to the original fuel rod(s) and/or which contains structural repairs so it can be handled by normal means.” The applicant stated that this definition is provided for clarification purposes and is a subset of “Undamaged Fuel.” It is a common practice for nuclear fuel assemblies to be repaired by the removal of a damaged fuel rod and replaced with a dummy rod. This allows the fuel assembly to be returned to the reactor core. The NRC has approved this use in specific applications, and has provided guidance to 10 CFR Part 50 licensees to ensure that this is performed within the requirements of the licensees 10 CFR Part 50 TS without creating an unreviewed safety question. A repaired/reconstituted fuel assembly is restored to a condition within the bounds of its original design and safety analysis. The staff, therefore, finds this type of assembly to be a subset of “undamaged fuel” and the applicant’s proposed definition consistent with ISG-1, and therefore acceptable.” (pp. 10-13) http://pbadupws.nrc.gov/docs/ML1426/ML14262A476.pdf
“SAFETY EVALUATION REPORTDOCKET NO. 72-1014 HOLTEC INTERNATIONAL HI-STORM 100 CASK SYSTEM CERTIFICATE OF COMPLIANCE NO. 1014 AMENDMENT NO. 8, REVISION NO.1”
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