NL-15-1489, 10 CFR 71.95 Report on Potential Issues Involving Radwaste Cask 8-1208

10 CFR 71.95 Report on Potential Issues Involving Radwaste Cask 8-1208

ML15229A111
Person / Time
Site:	Farley
Issue date:	08/17/2015
From:	Gayheart C Southern Co, Southern Nuclear Operating Co
To:	Document Control Desk, Office of Nuclear Material Safety and Safeguards
References
NL-15-1489
Download: ML15229A111 (10)

Text

Charyl A. Gayheart Southam Nuclear Vice President

• Farley Operating Company, Inc.

Farley Nuclear Plant Post Office Drawer 470 Ashford. Alabama 3631 2 Tel334.814.4511 Fax 334.814.4575 SOUTH ER , \

August 17, 2015 COMPANY Docket Nos.: 50-348 NL-15-1489 50-364 U. S. N4clear Regulatory Commission ATTN: Document Control Desk Washington, D. C. 20555-0001 Joseph M. Farley Nuclear Plant Units 1 and 2 10 CFR 71.95 Report on Potential Issues Involving Radwaste Cask 8-1208 Ladies and Gentlemen:

This report is submitted, pursuant to 10 CFR 71 .95(a)(3), regarding potential instances in which the conditions of approval in Certificate of Compliance (CoC)

1. 9168 for the EnergySolutions model8-12 08 cask may not have been observed in making shipments from Joseph M. Farley Nuclear Plant (Farley). This report is based on our discovery of the potential condition on June 24, 2015, when EnergySolutions (the certificate holder) notified Farley 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 for type '8' radioactive shipments at Farley. For the period detailed in the letter from EnergySolutions (September 2013 to the end of June 2015), Farley made four radioactive type '8' shipments utilizing the EnergySolutions model 8-1208 cask.

March 13, 2014 Cask 8-1208-1 Shipment RWS 14-01 May 14,2014 Cask 8-1208-2 Shipment RWS 14-02 December 12, 2014 Cask 8-1208-2 Shipment RWS 14-08 February 19, 2015 Cask 8-1208-2 Shipment RWS 15-02 No future shipments are planned by Farley using the 8-1208 deficient gasket configuration as described in the enclosed report. 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-15-1489 Page2 This letter contains no NRC commitments. If you have any questions, please contact Greg Bell at {334) 814-4765.

Sincerely, Ms. C. A. eart Vice President - Farley

Enclosure:

10 CFR 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. Bast, Executive Vice President & Chief Nuclear Officer Ms. C. A. Gayheart, Vice President- Farley Mr. M.D. Meier, Vice President- Regulatory Affairs Mr. D. R. Madison, Vice President- Fleet Operations Mr. B. J. Adams, Vice President- Engineering Ms. B. L. Taylor, Regulatory Affairs Manager- Farley Mr. G. L. Bell, Licensing Supervisor- Farley RTYPE: CFA04.054 U. S. Nuclear Regulatory Commission Mr. V. M. McCree, Regional Administrator Mr. S. A. Williams, NRR Project Manager - Farley Mr. P. K. Niebaum, Senior Resident Inspector- Farley

Joseph M. Farley Nuclear Plant Unit 1 and 2 10 CFR 71.95 Report on Potential Issues Involving Radwaste Cask 8-1208 Enclosure 10 CFR 71.95 Report on 8-1208 Cask to NRC by EnergySolutions

Enclosure to NL-15-1489 10 CFR 71 .95 Report on 8-1208 Cask to NRC by EnergySolutions

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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 ATfN: 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 information required by 10 CFR 71.95(a)(3) for instances in which the conditions ofapprova1 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 Shrum Dan Shrum

!JaJ£~

Senior Vice President, Regulatory Affairs Jun 24 2015 2:58PM

(_ ")Si!?.n EnergySolutions LLC Attaclm1ent : Failure to Observe Certificate of Compliance Cond1t1ons for the 8-120B 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

Enclosure to NL-15-1489 10 CFR 71.95 Report on 8-1208 Cask to NRC by EnergySolutions

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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 manifold, saving test tin1e and reducing personnel exposw*es. The amount of reduction of the test sensitivity cannot be determined for any pmticular shipment due to several reasons as discussed below. The gasket may 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 uncettain whether, or by how much, the sensitivity of the vent port pre-shipment leak tests was reduced because: I) Use ofthe 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 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 manifold gasket, as discussed in ( 4) below.

b) Dates of Occurrences From September 2013, when pre-shipment leak tests were first performed using the neoprene gasket, to present, approximately 100 shipments were made by EnergySolutions as the licensee. Most of these shipments used the neoprene gasket to perform the pre-shipment leak rate test ofthe vent pott.

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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 an 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.

Attaclunent 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 port plug cap screw when it is compressed by the bottom end of the test manifold 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 may not have provided the required test sensitivity of lxl0- 3 ref-cm3/sec.

e) Systems or Secondary Functions Affected Not applicable.

f) Method of Discovery of the Error 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 perf01med prior to every shipment in accordance with the requirements of Chapter 7 of the SAR. In addition, periodic and maintenance leak tests of the containment seals, using helium as the test gas, were performed after maintenance, repair, or replacement of the containment 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 SARis a factor of9 more sensitive than the 1xl0"3 ref-cm3/sec required by Chapter 8 of the SAR. However, due to the uncertainties in the effects of the gasket, and the behavior of seals in series, it is not possible to confirm 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 lxl0-3 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 a118-120B 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 EnergySolutions 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 oflndividuals to Radiation or Radioactive Materials None.

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Enclosure to NL-15-1489 10 CFR 71.95 Report on 8-1208 Cask to NRC by EnergySolutions

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Attachment 1 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 ofthe 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 ofthe 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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Enclosure to NL-15-1489 10 CFR 71.95 Report on 8-1208 Cask to NRC by EnergySolutions

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MANIFOLD STINGER PRIMARY LID MANIFOLD SLEEVE NUT MANIFOLD 0-RING SEAL (NOT LICENSED EQUIPMEND NEOPRENE GASKET- SHOWN UN COMPRESSED VENT PORT CAP SCREW (NOT LICENSED EQUIPMENT) 6

Enclosure to NL-15-1489 10 CFR 71.95 Report on 8-1208 Cask to NRC by EnergySolutions

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Con*ective 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 Ll~ \ -

VENT PORT SEAL NEW MANIFOLD GASKET (SHOWN UNCOMPRESSED)

VENT PORT CAP SCREW 7