Information Notice 2014-08, Need for Continuous Monitoring of Active Systems (Including Vacuum Drying Process)

Need for Continuous Monitoring of Active Systems (Including Vacuum Drying Process)

ML14121A089
Person / Time
Issue date:	05/16/2014
From:	Mark Lombard NRC/NMSS/SFST
To:
Solis J
References
IN-14-008
Download: ML14121A089 (4)

UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF NUCLEAR MATERIAL SAFETY AND SAFEGUARDS

WASHINGTON, DC 20555-0001

May 16, 2014

NRC INFORMATION NOTICE 2014-08:

NEED FOR CONTINUOUS MONITORING OF

ACTIVE SYSTEMS IN LOADED SPENT FUEL

STORAGE CANISTERS (INCLUDING VACUUM

DRYING PROCESS)

ADDRESSEES

All holders of and applicants for an independent spent fuel storage installation license under

Title 10 of the Code of Federal Regulations (10 CFR) Part 72, Licensing Requirements for the

Independent Storage of Spent Nuclear Fuel, High-Level Radioactive Waste, and Reactor- Related Greater than Class C Waste, 10 CFR Part 72 Certificate of Compliance holders, and

all 10 CFR Part 72 general licensees.

PURPOSE

The U.S. Nuclear Regulatory Commission (NRC) is issuing this information notice (IN) to

supplement IN 2011-10 Thermal Issues Identified during Loading of Spent Fuel Storage Casks

to inform addressees of additional information and lessons learned pertaining to the incident

that occurred during the loading of spent fuel storage canisters at the Byron Generating Station.

NRC expects that recipients will review the information for applicability to their facilities and take

actions, as appropriate, to avoid similar problems. Suggestions contained in this IN are not NRC

requirements; therefore, no specific action or written response is required.

DESCRIPTION OF CIRCUMSTANCES

On August 28-29, 2010, a Holtec HI-STORM 100 spent fuel storage system multipurpose

canister containing fuel assemblies and located within a transfer cask was left unattended for

the evening. A cooling system, which circulated water in the annulus between the canister and

transfer cask to keep cladding temperatures below allowable limits, was found to be inoperable

the next morning. The NRC conducted a reactive team inspection at the Byron Generating

Station in September 2010, and issued Inspection Report Nos. 05000454/2010007,

05000455/2010007, and 07200068/2010002 (Agencywide Documents Access and

Management System (ADAMS) Accession No. ML103140226). Issues that arose as a result of

the reactive team inspection were also addressed during a scheduled design and quality

assurance inspection at Holtec International, who holds the HI-STORM 100 Certificate of

Compliance, from October 25 -29, 2010 (Inspection Report No. 72-1014/10-201, ADAMS

Accession No. ML110450157).

ML14121A089 On May 2, 2011, the NRC issued Information Notice 2011-10 (ADAMS Accession No.

ML111090200) to inform addressees of the incident that occurred during the loading of spent

fuel storage canisters at the Byron Generating Station. In this information notice the NRC

expected that recipients would review the information for applicability to their facilities and take

actions, as appropriate, to avoid similar problems.

However, after issuing IN 2011-10, the NRC continued to have technical discussions regarding

the vulnerability of unattended vacuum drying process. On February 6, 2014, the NRC held a

public meeting at NRC headquarters to discuss potential safety issues associated with the

vacuum drying process during spent nuclear fuel cask loading operations (ADAMS Accession

No. ML14065A014). During the public meeting the NRC provided an overview of potential

issues associated with the Byron Generating Station event and a representative from the utility

provided an overview of the event and actions taken at the Byron Generating Station. A

representative from the Nuclear Energy Institute provided an overview related to the safety

significance of the event and actions taken by industry in response to IN 2011-10. In general

these actions meet NRCs expectations that the vacuum drying process should be continuously

monitored during all phases. As a result of the public meeting, the NRC learned what actions

have been taken by industry in response to IN 2011-10 and what type of additional information

need to be provided in this supplement, as described below.

DISCUSSION

The inspection reports referenced above provide detailed summaries of the incident as well as

findings and observations, underlying implications, and other information. As a result of the

inspections, subsequent reviews and technical analyses, IN 2011-10, and discussions during

the public meeting held on February 6, 2014, the NRC identified unresolved potential safety

issues related to the incident:

(1) A loaded spent fuel storage cask was left unattended with an inoperable cooling system.

Even though vacuum drying was secured when the cooling system failure occurred, the

entire process was put at risk because the cooling system failure went undetected for an

entire night, which resulted in an uncontrolled temperature increase inside the canister.

(2) Subsequent failure of the cooling system resulted in the licensee not being in compliance

with the cask technical specifications of ensuring that the peak cladding temperature is

maintained below recommended limits and that the spent fuel is maintained under flooded

or inert conditions if a failure of the vacuum drying system occurred.

In summary, cask vendors and licensees should review their operating procedures to ensure

they are adequate to maintain peak cladding temperature below recommended limits during

vacuum drying. To achieve these objectives, the cask operating procedures should also be

reviewed to determine if they adequately address the need for continuous monitoring of the

vacuum drying process. Cask vendors and licensees should consider the need for continuous

monitoring of the vacuum drying process such that operators are available to take any

necessary actions to put the system into compliance with technical specifications, if a system

failure occurred. The monitoring can be done by means other than direct observation.

CONTACT

This IN requires no specific action or written response. Please direct any questions about this

matter to the technical contact listed below.

/RA/ A. Hsia for

Mark Lombard, Director

Division of Spent Fuel Storage and Transportation

Office of Nuclear Material Safety

and Safeguards

Technical Contact:

Jorge Solis, NMSS/SFST/TCB

301-287-9094 E-mail: Jorge.Solis@nrc.gov

Note: NRC generic communications may be found on the NRC public Web site, http://www.nrc.gov, under Electronic Reading Room/Document Collections.

CONTACT

This IN requires no specific action or written response. Please direct any questions about this

matter to the technical contact listed below.

/RA/ A. Hsia for

Mark Lombard, Director

Division of Spent Fuel Storage and Transportation

Office of Nuclear Material Safety

and Safeguards

Technical Contact:

Jorge Solis, SFST

301-287-9094 E-mail: Jorge.Solis@nrc.gov

Note: NRC generic communications may be found on the NRC public Web site, http://www.nrc.gov, under Electronic Reading Room/Document Collections.

G:\\SFST\\Solis\\IN-2014-008-ML14121A089.doc

ADAMS P8 Accession No.: ML14121A089

OFC:

NMSS

E

NMSS

E

NMSS

E

NMSS

E

NMSS

E

NMSS

E

NAME:

JSolis

CAraguas

MSampson

REinziger

THsia

MLombard

DATE:

04/29/14

04/29/14

04/30/14

05/01/14

05/01/14

05/16/14 OFFICIAL RECORD COPY