ML18285A811
| ML18285A811 | |
| Person / Time | |
|---|---|
| Site: | HI-STORM 100 |
| Issue date: | 09/28/1998 |
| From: | Holtec |
| To: | Office of Nuclear Material Safety and Safeguards |
| References | |
| 5021048 | |
| Download: ML18285A811 (2) | |
Text
Attachment 1 to Holtec Letter 5021048 LAR 1040-4, REVISION 0
SUMMARY
OF PROPOSED CHANGES Page 1 of 2 Proposed Change #1 Update the Technical Specification for Radiation Protection.
Reason for Proposed Change #1 The reason for the change is outlined in Holtec Letters 5021041 (ML18024A451) and 5021045 (ML18241A092). Concerns were raised by NRC staff members that there was no connection between the dose rate measurement requirements in CoC 1040, Appendix A, Section 5.3.4 and design calculations for the system. Holtec therefore has updated the CoC and associated bases information to clearly articulate the basis for the CoC value. The change also modifies the description of the location of the measurements for clarification for the users.
Justification for Proposed Change #1 The revised dose rate value is based on the design basis fuel calculations previously performed for the HI-STORM UMAX System, with some margin added. Therefore, if a licensee detects a dose rate above this value, it is a clear indication that something is not in line with the design bases and corrective actions may be needed per CoC, Appendix A, Section 5.3.6 and Section 5.3.7. Note that this change does not modify the requirement under Sections 5.3.2 and 5.3.3 for the licensee to calculate a site specific surface dose rate limit based on site condition, ISFSI configuration, number of casks, and contents to confirm compliance with 10CFR72.104. As stated in Section 5.3.5, the lower of these limits shall be used to compare with measured values.
The revised measurement location ensures that the appropriate location of dose rates is measured. However, it is important to note that as long as the locations for measured and site-specific calculated values are the same, a successful comparison provides reasonable assurance that 10CFR72.104 is met.
Proposed Change #2 Update the Technical Specifications for the Vent Blockage LCO.
Reason for Proposed Change #2 The reason for the change is to clarify for the users the applicability of the requirements for vent blockage. The current LCO instructs users to inspect their vents during storage operations; however, the definition of storage operations begins when the MPC reaches the baseplate, which is prior to lid installation of the VVM. Inspecting the vents prior to lid installation does not provide reliable information about the cooling of the system after the lid is placed. Additionally, the operability definition has been moved to the bases chapter, which is more consistent with Part 50 Technical Specifications and therefore more in line with what the general licensees expect to see.
to Holtec Letter 5021048 LAR 1040-4, REVISION 0
SUMMARY
OF PROPOSED CHANGES Page 2 of 2 Justification for Proposed Change #2 There is no change to the technical evaluation of the vent blockage condition. The LCO is simply revised for clearer instructions to the user.
Proposed Change #3 Addition of a Type 1 version of the MPC-37 Reason for Proposed Change #3 This change includes a version of the MPC-37, known as Type 1 in the HI-STORM UMAX licensing basis. The only difference between the MPC-37 and MPC-37 Type 1 is that the Type 1 version is evaluated assuming the periphery basket flow holes are closed. This new type 1 MPC allows for design variations where those flow paths may not be open.
Justification for Proposed Change #3 The only design function impacted by the blockage of the flow holes is the heat transfer within the MPC. An evaluation of the MPC with blocked flow holes has been added to Chapter 4, and the corresponding heat load limitation has been added to the HI-STORM UMAX CoC.
Editorial Changes to the CoC
- Align HI-TRAC VW description with HI-STORM FW