40 CFR § 197.26 - What are the circumstances of the human intrusion?

---
identifier: "/us/cfr/t40/s197.26"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "40 CFR § 197.26 - What are the circumstances of the human intrusion?"
title_number: 40
title_name: "Protection of Environment"
section_number: "197.26"
section_name: "What are the circumstances of the human intrusion?"
chapter_name: "ENVIRONMENTAL PROTECTION AGENCY"
subchapter_number: "F"
subchapter_name: "RADIATION PROTECTION PROGRAMS"
part_number: "197"
part_name: "PUBLIC HEALTH AND ENVIRONMENTAL RADIATION PROTECTION STANDARDS FOR YUCCA MOUNTAIN, NEVADA"
positive_law: false
currency: "2026-04-05"
last_updated: "2026-04-05"
format_version: "1.1.0"
generator: "[email protected]"
authority: "Sec. 801, Pub. L. 102-486, 106 Stat. 2921, 42 U.S.C. 10141 n."
regulatory_source: "66 FR 32132, June 13, 2001, unless otherwise noted."
cfr_part: "197"
---


# 197.26 What are the circumstances of the human intrusion?

For the purposes of the analysis of human intrusion, DOE must make the following assumptions:

(a) There is a single human intrusion as a result of exploratory drilling for ground water;

(b) The intruders drill a borehole directly through a degraded waste package into the uppermost aquifer underlying the Yucca Mountain repository;

(c) The drillers use the common techniques and practices that are currently employed in exploratory drilling for ground water in the region surrounding Yucca Mountain;

(d) Careful sealing of the borehole does not occur, instead natural degradation processes gradually modify the borehole;

(e) Only releases of radionuclides that occur as a result of the intrusion and that are transported through the resulting borehole to the saturated zone are projected; and

(f) No releases are included which are caused by unlikely natural processes and events.