NL-15-1461, Submittal of 10 CFR 71.95 Report on Potential Issues Involving Radwaste Cask 8-120B

Submittal of 10 CFR 71.95 Report on Potential Issues Involving Radwaste Cask 8-120B

ML15233A540
Person / Time
Site:	Hatch, 07109168
Issue date:	08/21/2015
From:	Pierce C Southern Co, Southern Nuclear Operating Co
To:	Mark Lombard Document Control Desk, Division of Spent Fuel Management
References
NL-15-1461
Download: ML15233A540 (10)

Text

Charles R. Pierce Southern Nuclear Regulatory Affairs Director Operating Company, Inc.

40 Inverness Center Parkway Post Office Box 1295 Birmingham, AL 35242 Tel 205.992.7872 SOUTHERN << \

Fax 205.992.7601 NUCLEAR A SOUTHERN COMPANY August 21, 2015 Docket Nos.: 50-321 NL-15-1461 50-366 Mr. Mark Lombard, Director Division of Spent Fuel Storage and Transportation Office of Nuclear Material Safety and Safeguards U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D. C. 20555-0001 Edwin I. Hatch Nuclear Plant 10 CFR 71.95 Report on Potential Issues Involving Radwaste Cask 8-1208

Dear Mr. Lombard:

Southern Nuclear Operating Company (SNC) hereby submits this report pursuant to 10 CFR 71.95(a)(3) regarding potential instances in which the conditions of approval in Certificate of Compliance (CoC) #9168 for the EnergySolutions model 8-1208 cask may not have been observed in making shipments from Edwin I.

Hatch Nuclear Plant (Hatch). This report is based on our discovery of the potential condition on June 24, 2015, when EnergySolutions (the certificate holder) notified SNC of this potential condition. The potential condition involved the addition of a neoprene gasket under the test manifold in the vent port seal pre-shipment leak rate test which may have led to a reduction of the test sensitivity conducted as required by the Safety Analysis Report (SAR) for the 8-1208 cask.

The enclosed notification report from EnergySolutions provides the information related to the condition, as required by 10 CFR 71.95(a)(3), and is applicable to the use of the 8-1208 cask at Hatch. For the period detailed in the letter from EnergySolutions (September 2013 to the end of June 2015) Plant Hatch utilized the 8-1208 shipping cask with the condition described once.

Shipment ID# 13-6001. Date of shipment 10-10-13. This shipment was consigned to a resin processing facility in Erwin, TN owned by EnergySolutions.

No future shipments are planned by SNC of 8-1208 casks using the gasket configuration as described since EnergySolutions has replaced all of the subject gaskets with a modified version that does not have the potential to reduce the test sensitivity.

U. S. Nuclear Regulatory Commission NL-15-1461 Page2 This letter contains no NRC commitments. If you have any questions, 'please contact Ken McElroy at (205) 992-7369.

Respectfully submitted,

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C. R. Pierce Regulatory Affairs Director CRP/cdp

Enclosure:

10CFR 71.95 Report on 8-120B Cask to NRC by EnergySolutions cc: Southern Nuclear Operating Company Mr. S. E. Kuczynski, Chairman, President & CEO Mr. D. G. Best, Executive Vice President & Chief Nuclear Officer Mr. D. R. Vineyard, Vice President- Hatch Mr. M. D. Meier, Vice President- Regulatory Affairs Mr. D. R. Madison, Vice President- Fleet Operations Mr. B. J. Adams, Vice President- Engineering Mr. G. L. Johnson, Regulatory Affairs Manager- Hatch Mr. C. J. Collins, Licensing Supervisor- Hatch RTYPE: CHA02.004 U. S. Nuclear Regulatory Commission Mr. V. M. McCree, Regional Administrator Mr. R. E. Martin, NRR Senior Project Manager- Hatch Mr. D. H. Hardage, Senior Resident Inspector- Hatch

Edwin I. Hatch Nuclear Plant Unit 1 and 2 10CFR 71.95 Report on 8-1208 Cask to NRC by EnergySolutions Enclosure 10CFR 71.95 Report on 8-1208 Cask to NRC by EnergySolutions

June 24, 2015 ES-CD-0-2015-002

Dear Valued Customer:

On Monday June 1, 2015, an 8-1208 cask user identified a concern that the neoprene gasket could potentially affect the integrity of the vent port seal pre-shipment leak test. In response, EnergySolutions performed a series of tests that confirmed that the neoprene gasket can constrict on the head of the vent port plug cap screw when it is compressed by the manifold, resulting in a reduction of the test sensitivity.

The amount of reduction of the test sensitivity cannot be determined for any particular shipment due to several reasons. It is uncertain whether, or by how much, the sensitivity of the vent port pre-shipment leak tests was reduced because: 1) Use of the gasket was optional- the gasket may, or may not have been in place for the tests, and 2) The force with which the gasket was compressed during testing is unknown, so it is uncertain if it caused the gasket to constrict onto the head of the vent port cap screw.

The gasket may have been used .an as many as 100 shipments by EnergySo/utions or its customers with EnergySolutions as the licensee from September 2013 through June 2015. It was September 2013 when newly designed lids were installed. The condition was determined not to have significant safety consequence because the seals receive periodic helium leak testing as required by the SAR, the vent ports are rarely opened, there is a margin of conservatism of approximately a factor of 9 on the prescribed vent port leak rate test, and there have been no observations of contamination around the vent port openings that would suggest leakage. There will be no further tests made using the gaskets since Energy Solutions has replaced all of the subject gaskets with a modified version that does not have the potential to reduce the test sensitivity.

EnergySolutions filed the attached report with the NRC containing the information required by 10 CFR 71.95 on June 24, 2015. In the report, EnergySolutions describes the cause of the discrepancy and provides information that supports that there is no safety significance. We expect that the information required for individual users to make their own notifications is contained in this report. Reference to this report in individual user reports would be appropriate if you so choose.

We sincerely apologize for any inconvenience this issue may have caused within in your organization.

Our corrective actions as a result of this issue are intended to prevent recurrence of similar issues and to ensure the highest quality of products and services that we provide.

For additional details, please contact Aleksandr Gelfand at axgelfond@energysolutions.com or 803-591-9074.

Sincerely, Mark S. Lewis General Manager, Cask Logistics Logistics, Processing and Disposal EnergySolutions, LLC

Attachment:

Letter and Report to NRC on 8-1208 Cask cc: Dan Shum Aleksandr Gelfand 740 Osborn Road. Barnwell, South Carolina 29812 803.259.1781. Fax 803.259.1477

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June 24,2015 CD15-0149 Mark Lombard, Director Di\ is ion of Spent Fuel Management Office of Nuclear Material Safety and Safeguards U.S. Nuclear Regulatory Commission Washington DC 20555-0001 ATTN: Document Control Desk

Subject:

10 CFR 71.95 Report on the 8-120B Cask

Dear Mr. Lombard:

EnergySolutions hereby submits the attached report providing the infonnation required by 10 CFR 71.95(a)(3) for instances in which the conditions of approval in the Certificate of Compliance for the 8-120B Cask (Certificate of Compliance #9168) may not have been observed in making certain shipments. The circumstances described in this report are applicable to approximately 235 shipments made by EnergySolutions as a licensee and user of the 8-120B cask over a 21 month period.

If you have any questions regarding this submittal, please contact me at 801-649-2109.

Daniel B. Slmtm A{JaJ$/A_

Dan Shrum Jun 24 2015 2:58PM Senior Vice President, Regulatory Affairs EnergySolutions LLC

Attachment:

Failure to Observe Certificate of Compliance Conditions for the 8-1 20B Vent Port Leak Pre-Shipment Leak Test cc. Michele Sampson, Chief Spent Fuel Licensing Branch Pierre M. Saverot Licensing Branch 299 South Main Street, Suite 1700

• Salt lake City, Utah 84111 (801) 649-2000

• Fax: (801) 880-2879

• www.energysolutions.com

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Failure to Observe Certificate of Compliance Conditions for the 8- 120B Vent Port Pre-Shipment Leak Test June 24, 2015

1) Abstract During the vent port seal pre-shipment leak rate test, a neoprene gasket that was added under the test manifold may have reduced the test sensitivity below the required value. The test manifold and gasket are not licensed packaging components. The gasket was added to the test manifold on some or all shipments to more reliably seal the tnanifold, saving test time and reducing personnel exposw*es. The amount of reduction of the test sensitivity cannot be determined for any pat1icular shiptnent due to several reasons as discussed below. The gasket n1ay have been used on as many as 100 shipments by EnergySolutions as the licensee from September 2013 through June 2015. The condition was determined not to have significant safety consequence because the seals receive periodic helium leak testing as required by the SAR, the vent ports are only opened rarely, there is a margin of conservatism of approximately a factor of9 on the prescribed vent port leak rate test, and there have been no observations of contamination around the vent port openings that would suggest leakage.

There will be no further tests made using the gaskets since EnergySolutions has replaced all of the subject gaskets with a modified version that does not have the potential to reduce the test sensitivity.

It is uncet1ain whether, or by how much, the sensitivity of the vent port pre-shipment leak tests was reduced because: 1) Use of the gasket was optional- the gasket may, or may not have been in place for the tests, apd 2) The force with which the gasket was compressed during testing is unknown, so it is uncertain if caused the gasket to constrict onto the head of the vent port cap screw.

2) Narrative Description of the Event a) Status of Components All ofthe 8-120B packaging components are operating normally. The neoprene gaskets that caused the event have all be removed from service and replaced with a new tnanifold gasket, as discussed in (4) below.

b) Dates of Occunences From September 2013, when pre-shipment leak tests were first performed using the neoprene gasket, to present, approxn11ately 100 shiptnents were made by EnergySolutions as the licensee. Most of these shipments used the neoprene gasket to perfonn the pre-shipment leak rate test of the vent po11.

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c) Cause ofError New 8-120B lids went into service in September 2013. It was found that the manifold sometimes had problems sealing with the vent port on these new lids. EnergySolutions personnel found that adding a11 extra neoprene gasket helped to reduce the false test failures. Since the pre-shipment leak rate test is performed in a radiation environment, false failures are undesirable because they increase the personnel exposure. The personnel did not realize that the gaskets had the potential to reduce the test sensitivity.

Attachment 1 has a detailed description of the test configuration.

d) Failure Mode, Mechanism, and Effects The neoprene gasket can constrict on the head of the vent po1t plug cap screw when it is compressed by the bottom end of the test 1nanifold stinger, which could reduce the sensitivity of the pre-shipment leak test. Consequently, the vent port pre-shipment leak tests performed using the neoprene gasket n1ay not have provided the required test sensitivity of 1xl o-3 ref-cm3/sec.

e) Systetns or Secondary Functions Affected Not applicable.

f) Method of Discovery of the EITor On Monday June 1, 2015, an 8-120B cask user identified a concern that the neoprene gasket could potentially affect the integrity of the vent p01t seal pre-shipment leak test.

Later that week EnergySolutions performed a bench test that confirmed that the neoprene gasket can constrict on the head of the vent port plug cap screw when it is compressed by the manifold, resulting in a reduction of the test sensitivity.

3) Assessment of Safety Consequences Pre-shipment leak tests of all containment seals, including the vent port, were perfonned prior to every shipment in accordance with the requirements of Chapter 7 of the SAR. In addition, periodic and tnaintenance leak tests of the containment seals, using helium as the test gas, were performed after maintenance, repair, or replacement of the containn1ent seals in accordance with the requirements of Chapter 8 of the SAR.

The 8-120B preshipment leak rate test criteria were sized for the large primary lid. Since the vent port has a much smaller test volume, the test specification is conservative. Calculations show that the test specified in the S..<\R is a factor of 9 more sensitive than the 1x 1o-3 ref-ctn3/sec required by Chapter 8 ofthe SAR. However, due to the uncertainties in the effects of the gasket, and the behavior of seals in series, it is not possible to confrrm whether the reduction in sensitivity is offset by the test criteria conservatism.

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There has been no indication of any leakage from the vent port from any shipment, and therefore, no exposure of individuals to radiation or radioactive materials due to the gaskets.

It is also noted that it is unusual for the vent port seal to be opened during cask operations, in which case the previous helium leak test of the vent port seal provides added assurance of seal integrity.

Therefore, it is concluded that there has been no safety consequence from performing vent port pre-shipment leak tests that may not have provided the required test sensitivity of lx1 o-3 ref-cm3/sec.

4) Planned Corrective Actions EnergySolutions has taken corrective actions to assure that use of the old neoprene gasket design for the vent port pre-shipment leak test is immediately discontinued.

• EnergySolutions notified all 8-120B cask users with upcoming shipments to require use of a new procedure, in conjunction with the new manifold gasket design, for pre-shipment leak testing of the vent port seal on all future shipments.

• EnergySolutions designed and tested new manifold gasket design that does not constrict onto the head of the vent port plus screw when compressed, and therefore it does not reduce the test sensitivity. The new gaskets have been distributed to all upcoming shipment users. The new manifold gasket design is shown in Attachment 1.

The En~rgySolutions drawing for the 8-120B air drop manifold have been revised to include the new gasket seal, and the air pressure drop test procedure TR-TP-002 has been revised to incorporate the new pre-shipment leak test procedure for the vent port. Use of the new procedure and the new manifold gasket will assure that the pre-shipment leak test satisfies the required test sensitivity and that the manifold gasket is removed from the test port after completing the pre-shipment leak test.

5) Previous Similar Events Involving the 8-120B No previous similar events have been identified.

6) Contact for Additional Information Dan Shrum EnergySolutions Senior Vice President, Regulatory Affairs (801) 649-2109

7) Extent of Exposure of Individuals to Radiation or Radioactive Materials None.

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Attachment I Details of the 8-120B Vent Port Leak Rate Test Setup The 8-120B CoC requires the package to be prepared for shipment and operated in accordance with Chapter 7 of the SAR, and tested and maintained in accordance with Chapter 8 of the SAR.

Step 7.1.14 of the SAR requires a pre-shipment leak test of the primary lid, secondary lid, and vent port seals to be performed in accordance with Section 8.3.2.2 prior to every shipment to assure that the containment system is properly assembled. Per Table 8-2 of the SAR, the pre-shipment leak test of the vent port is performed by connecting a test manifold to the vent port, pressurizing the seal and head of the vent port cap screw to 18 psig with dry air or nitrogen, and monitoring the pressure for at least 15 minutes to assure that it does not drop by more than 0.1 psig.

The pre-shipment leak test of the vent port is a pressure drop test performed using a dedicated test manifold. The test manifold is not a part of the licensed package. It includes a stinger (shown below), an 0-ring seal that contacts the stinger and the bottom of the vent port hole, and a sleeve nut to compress the 0-ring seal. The test manifold was designed so that it surrounds the vent port cap screw, leaving a small gap between itself and the vent port cap screw. The 8-120B cask fleet began to ship with a new lid design in September 2013, and operations staff noted more frequent difficulty getting the manifold to seal. It became desirable to find a better way to seal the bottom of the manifold in order to minimize operator exposure. They found that adding a neoprene gasket (also not part of the licensed package) under the base of the stinger as shown below helped reduce testing time and exposure.

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Conective Action- Modified Test Seal The new manifold gasket design, shown below, replaces the manifold 0-ring seal and neoprene gasket previously used with a neoprene gasket that fits within the notch at the base of the manifold stinger.

MANIFOLD SLEEVE NUT PRIMARY_U~ \ --:-- - --n' VENT PORT SEAL NEW MANIFOLD GASKET (SHOWN UNCOMPRESSED)

VENT PORT CAP SCREW 7