DCL-17-073, Supplement to License Amendment Request 16-04 Revision 6. Development of Emergency Action Levels for Non-Passive Reactors.

Supplement to License Amendment Request 16-04 Revision 6. Development of Emergency Action Levels for Non-Passive Reactors.

ML17229B635
Person / Time
Site:	Diablo Canyon
Issue date:	08/17/2017
From:	Welsch J Pacific Gas & Electric Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
DCL-17-073
Download: ML17229B635 (9)

Text

Pacific Gas and Electric Company James M. Welsch Diablo Canyon Power Plant Vice President, Nuclear Generation Mail Code 104/6 P. 0. Box 56 Avila Beach, CA 93424 805.545.3242 Internal: 691.3242 August 17, 2017 Fax: 805.545.4884 PG&E Letter DCL-17-073 U.S. Nuclear Regulatory Commission 10 CFR 50.90 ATTN: Document Control Desk Washington, D.C. 20555-0001 Diablo Canyon Units 1 and 2 Docket No. 50-275, OL-DPR-80 Docket No. 50-323, OL-DPR-82 Supplement to License Amendment Request 16-04 Request to Adopt Emergency Action Level Schemes Pursuant to NEI 99-01.

Revision 6. "Development of Emergency Action Levels for Non-Passive Reactors"

References:

1. PG&E Letter DCL-17 -055, "Response to NRC Request for Additional Information Regarding License Amendment Request 16-04, 'Request to Adopt Emergency Action Level Schemes Pursuant to NEI 99-01, Revision 6, "Development of Emergency Action Levels for Non-Passive Reactors,""' dated June 21, 2017 (ADAMS Accession No. ML17179A018)

Dear Commissioners and Staff:

Reference 1 provided Pacific Gas & Electric's (PG&E's) response to an NRC Request for Additional Information (RAI) regarding License Amendment Request 16-04. In Enclosure 3 of that submittal was a clean copy .o f the "Diablo Canyon Power Plant Emergency Plan, Appendix D- Emergency Action Level Technical Basis Document."

Subsequent to that submittal, PG&E found two typographical errors. The first is with respect to the percent fuel clad damage noted on Page 248 of 308 of the basis document. The stated value was 1.8%. However, the correct value, from PG&E Calculation EP-CALC-DCPP-1602, Revision 1, is 1.08o/o. The second error is on Page 265 of 308 of the basis document and it pertains to containment radiation monitor readings indicative of-a release of reactor coolant in containment. The stated value is 40 R/hr. However, the correct value, as stated in the Threshold, is 5 R/hr.

This letter contains two attachments. Attachment 1 provides additional information regarding the calculation of percent fuel damage. Attachment 2 includes the corrected Pages 248 and 265 of the Diablo Canyon Power Plant Emergency Plan, Appendix D- Emergency Action Level Technical Basis Document.

A member of the STARS Alliance Callaway

• Diablo Canyon

• Palo Verde

• Wolf Creek

Document Control Desk PG&E Letter DCL-17-073 August 17, 2017 Page 2 Please replace Pages 248 and 265 of Enclosure 3 in Reference 1 with revised Pages 248 and 265 in Attachment 2.

If you have any questions or require additional information, please contact Mr. Hossein Hamzehee at 805-545-4720.

I state under penalty of perjury that the foregoing is true and correct.

Executed on August 17, 2017.

Sincerely, cb:.L()AL__

James Welsch Vice President, Nuclear Generation armb/44 743/50934838 Attachments cc: Diablo Distribution cc/enc: Scott A. Morris, NRC Region IV Administrator (Acting)

Chris W. Newport, NRC Senior Resident Inspector Balwant K. Singal, NRC Senior Project Manager A member of the STARS Alliance Callaway

• Diablo Canyon

• Palo Verde

• Wolf Creek

Attachment 1 PG&E Letter DCL-17-073 Attachment 1 Fuel Clad Loss Category C. Containment Radiation/RCS Activity Basis Supplemental Information

Fuel Clad Loss Category C. Containment Radiation/RCS Activity Basis Supplemental Information NEI 99-01 Revision 6, "Development of Emergency Action Levels for Non-Passive Reactors,"

Pressurized Water Reactor (PWR) Fuel Clad Barrier Thresholds, Loss 3.A, is described as the following: "the radiation monitor reading corresponds to an instantaneous release of all reactor coolant mass into the containment, assuming that reactor coolant activity equals 300 f.JCi/gm dose equivalent 1-131. Reactor coolant activity above this level is greater than that expected for iodine spikes and corresponds to an approximate range of 2 percent to 5 percent fuel clad damage. Since this condition indicates that a significant amount of fuel clad damage has occurred, it represents a loss of the Fuel Clad Barrier."

Pacific Gas & Electric (PG&E) developed an engineering calculation to determine the expected containment high range radiation monitor reading for the Loss of Fuel Clad Barrier 3.A. This was accomplished by calculating the percent fuel damage required to reach 300 f.JCi/gm dose equivalent 1-131 as a ratio to 100 percent of the gap source term.

PG&E used a source term consistent with guidance documents NUREG-1940, "RASCAL 4:

Description of Models and Methods," and NUREG-1465, "Accident Source Terms for Light-Water Nuclear Power Plants." This source term assumes that 100 percent of the gap source term is equal to 5 percent each of the noble gases (Kr, Xe), halogens (1, Br), and alkali metals (Cs, Rb) contained in the core. Using a source term consistent with these NUREGs yielded an approximate fuel damage of 1.08 percent to reach 300 f.JCi/gm dose equivalent 1-131 in the reactor coolant system. The resultant expected containment high radiation monitor reading was 272 R/hr which, for EAL purposes, was rounded to 300R/hr.

It should be noted that using different source terms such as those provided in NUREG-1228, "Source Term Estimation During Incident Response to Severe Nuclear Power Plant Accidents," results in a slightly different fuel clad damage and radiation monitor reading. For example, the gap source term in NUREG-1228 is 3 percent of the noble gases (Kr, Xe), 2 percent of the halogens (I, Br), and 5 percent of the alkali metals (Cs, Rb) contained in the core. Using the same engineering calculation methodology and an identical total core inventory, the NUREG 1228 source term yielded a required fuel damage of 2.7 percent to reach 300 tJCi/gm dose equivalent 1-131 and resultant containment high radiation monitor reading of 319 R/hr. The key difference between the NUREGs is the total quantity of noble gases and iodines assumed to be present in the fuel gap at the time of the accident, and the relative nuclide abundance that affects the calculated dose equivalent 1-131.

PG&E concluded that using a gap source term consistent with the more recent estimates from NUREG 1940 and NUREG 1465 was more appropriate for its NEI 99-01, Revision 6 Fuel Clad Loss threshold calculation and that the corresponding containment radiation monitor EAL threshold of 300 R/hr met the NRC approved NEI guidance.

Table 1 and Table 2 on the following page are provided to demonstrate that using two different source terms and core release fractions for total gap activity will change the fuel clad damage equivalency. Both calculations used 300 tJCi/gm dose equivalent 1-131 reactor coolant activity as the key input. These representations use the PG&E engineering calculation EP-CALC-DCPP-1602, 1

Fuel Clad Loss Category C. Containment Radiation/RCS Activity Basis Supplemental Information Revision 1, "Containment Radiation EAL Threshold Values" methodology which is the DCPP Basis for the Fuel Clad Loss containment radiation monitor reading EAL threshold.

2

Fuel Clad Loss Category C. Containment Radiation/RCS Activity Basis Supplemental Information Table 1: Calculation of percent clad damaged required to reach 300 microcuries per gram using NUREG-1940 halogen gap release fraction.

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Volume Conversion (g/lbm): 453.592 Rated Power (MWt): 3411 Halogen Core RF (%): 5.0% RCS Mass@ NOT (Ibm): 5.09E+05 Target DEI-131 (IJCi/g): 3.00E+02 RCS Liquid Mass@ NOT (g): 2.31 E+08

%Clad Damage:! 1.08%1 Table 2: Calculation of percent clad damaged required to reach 300 microcuries per gram using NUREG-1228 halogen gap fraction.

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Volume Conversion (g/lbm): 453.592 Rated Power (MWt): 3411 Halogen Core RF (o/o): 2.0% RCS Mass@ NOT (Ibm): 5.09E+05 Target DEI-131 (IJCi/g): 3.00E+02 RCS Liquid Mass@ NOT (g): 2.31 E+08

%Clad Damage:! 2.70%1 3

Attachment 2 PG&E Letter DCL-17-073 Attachment 2 Page 248 and 265 of 308 Diablo Canyon Power Plant Emergency Plan, Appendix D - Emergency Action Level Technical Basis Document

ATTACHMENT 2 Fission Product Barrier Loss/Potential Loss Matrix and Bases Barrier: Fuel Clad Category: C. CMT Radiation I RCS Activity Degradation Threat: Loss Threshold:

1. Containment radiation (RM-30 or RM-31) > 300 R/hr.

Definition(s):

None Basis:

ERO Decision Making Information Containment radiation monitor readings greater than 300 R/hr (ref. 1) indicate the release of reactor coolant, with elevated activity indicative of fuel damage, into the Containment. This value is higher than that specified for RCS barrier Loss C.1.

The radiation monitor reading in this threshold is higher than that specified for RCS Barrier Loss threshold C.1 since it indicates a loss of both the Fuel Clad Barrier and the RCS Barrier. Note that a combination of the two monitor readings appropriately escalates the ECL to a Site Area Emergency.

Background

Monitors used for this fission product barrier loss threshold are the Containment High Range Radiation Monitors RM-30 and RM-31. These monitors provide indication in the Control Room on PAM 2 with a range of 1R/hr to 1E7 R/hr (ref. 1).

The radiation monitor reading corresponds to an instantaneous release of all reactor coolant mass into the containment, assuming that reactor coolant activity equals 300 IJCi/gm dose equivalent 1-131. Reactor coolant activity above this level is greater than that expected for iodine spikes and corresponds to an approximately 1.08°/o fuel clad damage. Since this condition indicates that a significant amount of fuel clad damage has occurred, it represents a loss of the Fuel Clad Barrier.

DCPP Basis Reference(s):

1. EP-CALC-DCPP-1602 Containment Radiation EAL Threshold Values

2. NEI 99-01 CMT Radiation I RCS Activity Fuel Clad Loss 3.A I [Document No.] Rev. [X] Page 248 of 3081

ATTACHMENT 2 Fission Product Barrier Loss/Potential Loss Matrix and Bases Barrier: Reactor Coolant System Category: C. CMT Radiation/ RCS Activity Degradation Threat: Loss Threshold:

1. Containment radiation (RM-30 or RM-31) > 5 R/hr.

Definition(s):

N/A Basis:

ERO Decision Making Information Containment radiation monitor readings greater than 5 R/hr (ref. 1) indicate the release of reactor coolant to the Containment.

This value is lower than that specified for Fuel Clad Barrier Loss threshold C.1 since it indicates a loss of the RCS Barrier only.

There is no Potential Loss threshold associated with RCS Activity I Containment Radiation.

Background

The readings assume the instantaneous release and dispersal of the reactor coolant noble gas and iodine inventory associated with normal coolant activity, with iodine spiking, discharged into containment (ref. 1).

Monitors used for this fission product barrier loss threshold are the Containment High Range Radiation Monitors RM-30 and RM-31. These monitors provide indication in the Control Room on PAM 2 with a range of 1R/hr to 1E7 R/hr (ref. 1).

DCPP Basis Reference(s):

1. EP-CALC-DCPP-1602 Containment Radiation EAL Threshold Values

2. NEI 99-01 CMT Radiation I RCS Activity RCS Loss 3.A I [Document No.] Rev. [X] Page 265 of 3081